Characteristics of Rhegmatogenous Retinal Detachment After Refractive Surgery: Comparison With Myopic Eyes With Retinal Detachment HAE MIN KANG, CHRISTOPHER SEUNGKYU LEE, HYUN JOO PARK, KYU HO LEE, SUK HO BYEON, HYOUNG JUN KOH, AND SUNG CHUL LEE PURPOSE:
To evaluate the characteristics of rhegmatogenous retinal detachment (RD) in patients with previous laser in situ keratomileusis (LASIK) and compare them to RD in patients with previous laser assisted subepithelial keratomileusis (LASEK) and myopic patients with no previous refractive surgery. DESIGN: Retrospective, comparative case series. METHODS: In 106 eyes of 106 patients with RD, patients with previous refractive surgery included 21 eyes after LASIK and 13 eyes after LASEK; 72 myopic patients with refractive errors of L3.0 diopters or less were grouped as the R (L) group. Characteristics of RD included distribution of RD and associated retinal breaks, location and number of retinal breaks, presence of lattice degeneration, and axial lengths. RESULTS: The mean interval between refractive surgery and the onset of rhegmatogenous RD was 63.7 ± 43.5 months, occurring across a broad spectrum of time intervals. There were no significant differences among the LASIK group, the LASEK group, and the R (L) group in axial length (26.8 mm vs 26.4 mm vs 26.9 mm, respectively); in mean number of retinal holes/tears, (2.1/1.5, 0.9/1.4, 1.5/1.6, respectively); or in the presence of lattice degeneration (52.4% vs 46.2% vs 43.1%, respectively). Distribution of RD and associated retinal breaks were also not significantly different; retinal holes and tears were more prevalent in the temporal quadrants, and inferotemporal quadrants were the most commonly detached areas in both the LASEK and LASIK groups and in the R (L) group. CONCLUSIONS: Myopia is a well-known risk factor for rhegmatogenous RD and may contribute more to the development of RD in myopic patients after refractive surgery, rather than refractive surgery itself. (Am J Ophthalmol 2014;157:666–672. Ó 2014 by Elsevier Inc. All rights reserved.)
Accepted for publication Dec 2, 2013. From the Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea (H.M.K., C.S.L., H.J.P., K.H.L., S.H.B., H.J.K., S.C.L.); Department of Ophthalmology, Incheon International St. Mary’s Hospital, Incheon, South Korea (H.M.K.). Inquiries to Christopher Seungkyu Lee, Department of Ophthalmology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, South Korea; e-mail: [email protected]
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2014 BY
R
HEGMATOGENOUS RETINAL DETACHMENT (RD),
the most common type of RD, is caused by liquefied vitreous passing through a retinal break into the subretinal space, separating the neurosensory retina from the retinal pigment epithelium.1,2 Fundamental mechanisms leading to rhegmatogenous RD are largely unknown. The formation of retinal breaks is often preceded by vitreoretinal degeneration, the cause of which is unclear. One of the factors strongly associated with rhegmatogenous RD is myopia.3–5 Low myopes (0.75 to 2.75 diopters [D]) show an odds ratio of 3.14 for RD, and the odds ratio was shown to rise steeply with increasing myopic refractive errors in the Japanese population.4 Increased vitreous liquefaction, earlier posterior vitreous detachment, and higher incidence of vitreoretinal degeneration such as lattice degeneration are thought to be attributable to the higher prevalence in rhegmatogenous RD in myopes.2 Refractive surgeries, such as laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratomileusis (LASEK), have been popularized for correction of low to moderate myopia.6,7 Vision-threatening posterior segment complications can occur after refractive surgeries; they include macular hemorrhages, macular holes, and rhegmatogenous RD.8–14 The reported incidence of rhegmatogenous RD in those with histories of LASIK is not high, ranging from 0.033% to 0.25%.11,15–17 However, many have regarded a suction ring application during LASIK to be a potential risk factor for rhegmatogenous RD because this procedure may induce vitreous traction and detachment resulting from sudden decompression of the eye.18,19 A previous study found that retinal breaks were more commonly located in the inferotemporal quadrant in rhegmatogenous RD after LASIK.20 Whether this feature is characteristic of rhegmatogenous RD after LASIK is unclear because this finding was not compared to rhegmatogenous RD without prior LASIK. Herein, we studied the characteristics of rhegmatogenous RD in patients with previous LASIK and compared them to both rhegmatogenous RD in myopic patients with no previous refractive surgeries and to rhegmatogenous RD in patients with previous LASEK, which does not require a suction ring application, unlike LASIK.
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FIGURE 1. Distribution of the intervals between refractive surgery and the onset of rhegmatogenous retinal detachment in patients with prior refractive surgery. Note that the mean interval between refractive surgery and rhegmatogenous RD onset was 63.7 ± 43.5 months.
METHODS ENROLLMENT OF STUDY SUBJECTS:
We retrospectively reviewed 106 eyes of 106 patients who fulfilled the inclusion criteria at the Vitreoretinal Service Clinic of Yonsei University Medical Center between March 2007 and March 2012. This retrospective, comparative case series was performed with the approval of the Institutional Review Board of Yonsei University College of Medicine and conducted in accordance with the tenets of the Declaration of Helsinki. Inclusion criteria were patients with (1) nontraumatic rhegmatogenous RD who underwent surgical repair; (2) no previous surgical history other than corneal laser refractive surgery for the study group; and (3) 3.0 D or lower myopia without previous refractive surgery for the control group. Patients with concomitant ocular diseases, such as diabetic retinopathy, myopic choroidal neovascularization or uveitis at the time of surgery were excluded. The patients included 34 eyes of 34 patients who had histories of refractive surgery before the onset of rhegmatogenous RD (21 eyes after LASIK and 13 eyes after LASEK), and they were grouped as the refractive surgery group (R [þ] group). The remaining 72 myopic patients without previous refractive surgery were grouped as the nonrefractive surgery group (R [] group), or the control group. The control group was selected to include moderately myopic patients who would be typical candidates for LASIK or LASEK. Because of a lack of information about refractive errors before refractive surgery for the R (þ) group, the axial lengths of the affected eyes were used to confirm and compare the degrees of myopia between the R (þ) and the R () groups. No patient in VOL. 157, NO. 3
the R (þ) group showed myopic posterior staphyloma, so highly myopic patients with posterior staphyloma were excluded in the R () group. EXAMINATION: All patients received complete ocular examinations, including best-corrected visual acuity (BCVA), color fundus photography and ultrasonography. Follow-up visits were arranged in general at 1 week and 1 month after each surgery. Subsequent 3- to 6-month examinations were performed; they included BCVA and dilated fundus examinations with an indirect ophthalmoscope. STATISTICAL ANALYSIS: Patients’ characteristics were retrieved from their medical charts, including age at refractive surgery and development of rhegmatogenous RD, sex, and axial lengths (mm). BCVA by decimal visual acuity charts were converted into logarithm of the minimum angle of resolution (logMAR) values for statistical analysis. We evaluated the characteristics of RD, including numbers and locations of retinal tears and holes and the presence of lattice degeneration. In addition, rhegmatogenous RD extent (involved quadrants), location of the detached retina, and status of the macula (detached labeled as off and attached as on) were investigated by reviewing the operation notes. The rhegmatogenous RD eyes were also classified as 1 of 3 types: equatorial, oral or macular.21 SPSS Statistics 18.0 software for Windows (IBM, Somers, NY, USA) was used for statistical analysis. The Kolmogrov-Smirnov test was used to confirm normal distribution of the study population. For comparison of the eyes with and without prior refractive surgery, the Student t test
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TABLE 1. Comparison of Characteristics of Rhegmatogenous Retinal Detachment between Laser in situ Keratomileusis (LASIK) and Laser-Assisted Subepithelial Keratomileusis (LASEK) Groups
Retinal breaks Retinal hole only Retinal tear only Both Mean number of retinal holes (per eye) Mean number of retinal tears (per eye) Lattice degeneration Macula attached at baseline Location of retinal holes (quadrants) Superotemporal Superonasal Inferotemporal Inferonasal Location of retinal tears (quadrants) Superotemporal Superonasal Inferotemporal Inferonasal Detached area Superonasal quadrants Superotemporal quadrants Inferonasal quadrants Inferotemporal quadrants Inferior half Superior half Temporal half Nasal half Total
P valuea,b
LASIK group (n ¼ 21)
LASEK group (n ¼ 13)
11 (52.4%) 5 (23.8%) 5 (23.8%) 2.1 6 2.1
8 (61.5%) 4 (30.8%) 1 (7.7%) 0.9 6 0.7
.054a
1.5 6 0.6
1.4 6 0.5
.492a
11 (52.4%) 8 (38.1%)
6 (46.2%) 5 (38.5%)
.658b .929b .765b
5 (31.3%) 1 (6.3%) 8 (50.0%) 2 (12.4%)
1 (11.1%) 2 (22.2%) 6 (66.7%) 0 (0.0%)
2 (20.0%) 3 (30.0%) 4 (40.0%) 1 (10.0%)
3 (60.0%) 0 (0.0%) 2 (40.0%) 0 (0.0%)
.399b
.366b
.398b 2 (9.5%) 2 (9.5%)
1 (7.6%) 4 (30.8%)
1 (4.8%) 0 (0.0%) 7 (33.3%) 5 (23.8%) 3 (14.3%) 0 (0.0%) 1 (4.8%)
0 (0.0%) 3 (23.1%) 3 (23.1%) 2 (15.4%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
a
Mann-Whitney U test for continuous variables. Wilcoxon signed-rank test for categorical variables. P < 0.05 was set for clinical significance.
b
for continuous variables and the x2 test for categorical variables were used. For subgroup analysis, nonparametric analysis was used: the Mann-Whitney U test for continuous variables and the Wilcoxon signed-rank test for categorical variables. Results with P less than 0.05 were considered statistically significant.
RESULTS CHARACTERISTICS OF THE PATIENTS: In 106 eyes of 106 patients, 34 eyes (34 patients) had histories of
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refractive surgery, whereas 72 eyes (72 patients) with myopia had had no previous refractive surgery. Of the patients, 56 (52.8%) were male, including 14 males with prior refractive surgery and 42 patients with myopic RD. The mean follow-up period after retinal reattachment surgery was 13.5 6 4.6 months. All patients achieved retinal reattachment after surgery, among which 10 eyes (9.4%) underwent surgical repair of redetached retina. After RD surgery, mean BCVA improved from 0.76 6 0.88 logMAR (Snellen equivalent 20/115) at baseline to 0.38 6 0.67 logMAR (Snellen equivalent 20/47) at the last follow-up visits (P ¼ .001). The mean age at rhegmatogenous RD onset was 33.6 6 9.8 years and mean symptom duration was 3.1 6 6.8 weeks in symptomatic cases. In all patients, 19 eyes of 19 patients had no visual symptoms, and rhegmatogenous RD was diagnosed during a routine fundus examination. Of 34 eyes with prior refractive surgery, 21 eyes (61.8%) underwent LASIK and 13 eyes (38.2%) received LASEK. The mean age at the time of refractive surgery was 29.6 6 7.8 years, and the mean interval between refractive surgery and rhegmatogenous RD onset was 63.7 6 43.5 months. None of the patients with prior refractive surgery received any treatment with barrier laser at the time of refractive surgery. The distribution of patients according to the interval between refractive surgery and rhegmatogenous RD onset is shown in Figure 1. The mean refractive errors in 72 patients in the R () group were 4.5 6 4.0 D in affected eyes and 4.6 6 4.4 D in unaffected eyes. COMPARISON BETWEEN EYES WITH PRIOR LASIK AND LASEK: The mean age at the time of refractive surgery
was 31.5 6 7.8 years in the LASIK group and 26.5 6 6.9 years in the LASEK group (P ¼ .063). The mean age at onset of rhegmatogenous RD was older in the LASIK group (38.4 6 8.8 years) than in the LASEK group (28.9 6 8.2 years) (P ¼ .003). The mean interval between refractive surgery and onset of rhegmatogenous RD was longer in the LASIK group (85.8 6 37.9 months) than in the LASEK group (28.1 6 23.9 months) (P ¼ .001). The mean axial length was not significantly different in the 2 groups: 26.8 6 1.7 mm in the LASIK group and 26.4 6 0.8 mm in the LASEK group (P ¼ .398). Mean BCVA at baseline was 0.75 6 0.73 logMAR (Snellen equivalent 20/112) in the LASIK group and 0.69 6 0.42 logMAR (Snellen equivalent 20/97) in the LASEK group (P ¼ .425). Mean BCVA improved in both groups after RD surgery when compared with baseline: 0.28 6 0.21 logMAR (Snellen equivalent 20/38) in the LASIK group, and 0.13 6 0.26 logMAR (Snellen equivalent 20/26) in the LASEK group (P ¼ .210). There were no statistically significant differences between the 2 groups in characteristics of rhegmatogenous RD and retinal breaks (Table 1). The distribution of retinal breaks of each group is shown in Figure 2.
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FIGURE 2. Distribution of retinal holes and retinal tears associated with rhegmatogenous retinal detachment after refractive surgery. Location of retinal breaks was assessed using the operation at the time of retinal reattachment surgery. (Left) Eyes with prior laser in situ keratomileusis (LASIK). (Right) eyes with prior laser-assisted subepithelial keratomileusis (LASEK). Note that the round figure represents a retinal hole, and the crescent shape represents a retinal tear.
COMPARISON BETWEEN EYES WITH PRIOR LASIK AND MYOPIC EYES WITH NO PREVIOUS REFRACTIVE SURGERY:
We compared the eyes with prior LASIK (LASIK group) and myopic eyes without previous refractive surgery (R [] group). The mean age at rhegmatogenous RD onset was older in the LASIK group (38.4 6 8.8 years) than in the R () group (33.1 6 9.9 years) (P ¼ .029). The mean axial length was 26.83 6 1.73 mm in the LASIK group and 26.9 6 1.8 mm in the R () group (P ¼ .893). The mean BCVA at baseline was 0.75 6 0.73 logMAR (Snellen equivalent 20/112) in the LASIK group, and 0.85 6 0.96 logMAR (Snellen equivalent 20/141) in the R () group (P ¼ .662). Mean BCVA at last visit was 0.28 6 0.21 logMAR (Snellen equivalent 20/38) in the LASIK group and 0.41 6 0.38 logMAR (Snellen equivalent 20/51) in the R () group (P ¼ .106). The distribution of rhegmatogenous RD and associated retinal breaks were not significantly different in the 2 groups, as shown in Table 2.
DISCUSSION WE COMPARED THE CLINICAL CHARACTERISTICS OF RHEG-
matogenous RD and associated retinal breaks between myopic patients with and without previous refractive surgery and found no significant difference. In the R (þ) group, retinal holes and tears were located predominantly in the temporal quadrants (80.0% and 73.3%, respectively). These findings are compatible with a previous study in which the predominant location of retinal breaks was reported in the temporal quadrants.20 These authors explained that extra pressure due to the temporal handle of surgical microkeratomes during LASIK might be responsible for the temporal predominance of retinal breaks.20 However, in our study, retinal holes and tears in the R VOL. 157, NO. 3
() group were more prevalent in the temporal quadrants (76.9% and 51.2%, respectively) than in the nasal quadrants. The inferotemporal quadrants were the most commonly involved areas of RD in the LASIK group (52.4%), which was also consistent with a previous study.20 However, the R () group also showed the inferotemporal quadrants as being the most commonly involved area of RD (66.7%). Common development of retinal breaks in the temporal quadrants, especially in the interotemporal quadrants, may explain the frequent finding of temporal rhegmatogenous RD. The comparison of rhegmatogenous RD features between LASIK eyes and LASEK eyes showed no significant differences except in the mean numbers of retinal holes per eye. Those with prior LASIK showed significantly more retinal holes per eye than those with prior LASEK. This may be an incidental finding, rather than a characteristic finding of RD after LASIK because there was no significant difference in the mean number of retinal holes and tears compared to patients in the R () group. Retinal breaks in the LASEK group had temporal predominance (77.8% of retinal holes and 100% of retinal tears); similarly, rhegmatogenous RD in the LASEK group commonly involved the interotemporal quadrants (46.2%). These characteristics of the LASEK group were similar to those of the LASIK group and the R () group. Previous studies have paid particular attention to rhegmatogenous RD after LASIK because the application of the suction rings during the LASIK procedure may induce anomalous vitreous detachment and work as a causative factor for the development of rhegmatogenous RD.18,19 However, rhegmatogenous RD could develop even after LASEK, and we found that the characteristics of RD and associated retinal breaks were not significantly different in eyes after LASIK and eyes after LASEK. Moreover, the mean interval between refractive surgery and the onset of rhegmatogenous RD was actually longer in the LASIK group than in the
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TABLE 2. Comparison of Characteristics of Rhegmatogenous Retinal Detachment (RD) Between the Eyes With (Refractive Group) and Those Without (Nonrefractive Group) Prior to Refractive Surgery LASIK group (n ¼ 21)
Mean number of retinal holes 2.1 6 2.1 (per eye) Mean number of retinal tears 1.5 6 0.6 (per eye) Retinal breaks Retinal hole only 11 (52.4%) Retinal tear only 5 (23.8%) Both 5 (23.8%) Macula attached at baseline 8 (38.1%) Lattice degeneration 11 (52.4%) Location of retinal holes (quadrant) Superotemporal 5 (31.3%) Superonasal 1 (6.3%) Inferotemporal 8 (50.0%) Inferonasal 2 (12.4%) Location of retinal tears (quadrant) Superotemporal 2 (20.0%) Superonasal 3 (30.0%) Inferotemporal 4 (40.0%) Inferonasal 1 (10.0%) Detached area Superonasal quadrant 2 (9.5%) Superotemporal quadrant 2 (9.5%) Inferonasal quadrant 1 (4.8%) Inferotemporal quadrant 0 (0.0%) Inferior half 7 (33.3%) Superior half 5 (23.8%) Temporal half 3 (14.3%) Nasal half 0 (0.0%) Total 1 (4.8%)
Nonrefractive group (n ¼ 72)
P valuea,b
1.5 6 1.8
.237a
1.6 6 0.7
.492a .399b
35 (48.6%) 27 (37.5%) 10 (13.9%) 30 (41.7%) 31 (43.1%)
.729b .578b .765b
13 (25.0%) 4 (7.7%) 27 (51.9%) 8 (15.4%) .366b 10 (24.4%) 14 (34.2%) 11 (26.8%) 6 (14.6%) .525b 2 (2.8%) 8 (11.0%) 1 (1.4%) 9 (12.5%) 21 (29.2%) 10 (13.9%) 13 (18.1%) 3 (4.2%) 5 (6.9%)
a
Student t test for continuous variables. x test for categorical variables. P < 0.05 was set for clinical significance.
b 2
LASEK group. If vitreous traction and detachment from a suction ring application were significant factors in rhegmatogenous RD development, one would expect to find a shorter interval to rhegmatogenous RD in eyes after LASIK than in eyes after LASEK, which does not require a suction ring application. A suction ring is placed just behind the limbus with a vacuum device to firm the cornea during LASIK. When the suction ring induces an increase in intraocular pressure and is suddenly released, the anterior segment is rapidly drawn into the vacuum chamber, with its shape changing rapidly.19 During this process, all structures posterior to the suction ring are compressed and decompressed in sequence, possibly leading to acute vitreoretinal traction 670
at the vitreous base and posterior pole.19,21 In this respect, rhegmatogenous RD after LASIK may be regarded as a traumatic RD. However, no patients with rhegmatogenous RD after LASIK or LASEK have shown oral-type RD, which is characteristic after blunt trauma.21,22 This may be due to differences in the mechanism of compression and decompression processes between LASIK and blunt trauma. In blunt trauma, equatorial expansion of the eyeball is an active process, resulting from the force exerted on the anterior portion of the eye.21,23,24 Decompression, then, follows to resume the normal shape of the eyeball.21–24 Conversely, the suction-ring application results in elongation of the eyeball. The equatorial expansion results from a passive decompression process. In other words, equatorial expansion results from active compression during blunt trauma, whereas it results from passive decompression during a suction ring application (Fig. 3). Active equatorial expansion during blunt trauma can result in oral-type RD, including dialysis and giant retinal tears.21–24 Passive equatorial expansion from a suction ring application may not pose a significant risk for inducing vitreous detachment and RD. Another previously proposed mechanism for rhegmatogenous RD after refractive surgeries is shock waves generated during excimer laser treatment.9,25–27 These waves can possibly result in mechanical stress on the eye and affect structures in the posterior segments. Although it is quite possible that any impact to the eye may influence the vitreoretinal dynamics and cause retinal breaks, contribution of shock waves from excimer laser may not be significant because there was no significant difference in the RD features between the R (þ) group and the R () group. Rather than the impact of refractive surgery, our findings suggest that myopia and the associated changes of the eyes may contribute more to the development of RD in patients after refractive surgery. It is well known that myopia itself is a strong risk factor for RD.3–5 Refraction was identified as the major identifiable risk factor for RD, with an adjusted odds ratio in the range of 1 D to 3 D of 4.4, increasing to 9.9 in the range of 3 D to 8 D.5 For any _1 D), the corrected odds ratio was degree of myopia (< 7.5.5 The odds ratio rose steeply with increasing myopia to greater than 80 for myopia in excess of 15 D.4 In myopic eyes, posterior vitreous detachment occurs early, lattice degeneration is more common, and the retina is thinner than in emmetropes, leading to a more common occurrence of rhegmatogenous RD.3,28–33 Development of vitreous liquefaction is more extensive and occurs earlier in myopic eyes, and it is significantly correlated with an axial length of greater than 30 mm.32,33 Because eyes that have undergone refractive surgery are myopic, they already are at risk for development of rhegmatogenous RD. The mean interval of 63.7 6 43.5 months between refractive surgery and onset of RD was generally longer in this study than in previous studies, which showed a mean
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FIGURE 3. Postulated vitreoretinal changes due to blunt trauma (Top) and laser in situ keratomileusis (LASIK) (Bottom). (Top) In blunt trauma, equatorial expansion of the eyeball is an active process, resulting from the force exerted on the anterior portion of the eye. Decompression, then, follows to resume the normal shape of the eyeball. (Bottom) During LASIK, a suction ring application results in an anterior-posterior elongation of the eyeball. Equatorial expansion results from a passive decompression process after release of the suction ring. Then the shape of the eyeball is normalized.
interval of between 12 and 31 months.9–11,15,16,18,20 However, previous studies also showed variations in the intervals between refractive surgery and the onset of RD.9–11,15,16,18,20 This variability in the interval between refractive surgery and RD onset may imply that refractive surgery may not contribute any more significantly to the development of RD than myopia itself. There are several limitations in this study. This was a retrospective study with a relatively small study population, which may affect the statistical significance of our findings. However, given the low incidence of rhegmatogenous RD after refractive surgery and the variable onset interval, a prospective study with a sufficient number of subjects for adequate statistical power is virtually nonexecutable. Another drawback of the present study is the lack of data concerning refractive error in patients involved in the study before refractive surgeries. Vitreoretinal abnormalities become more likely with increasing myopia,3–5 so it is important to include patients with similar degrees of myopia for comparative study. However, the mean axial lengths of the R (þ) group and the R () group were the same. There was no difference in axial lengths between LASIK eyes and LASEK eyes, either. Furthermore, the mean refractive error of the R () group was 4.5 6 4.0 D, which may represent the mean refractive error in patients who would
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be potential candidates for refractive surgery; the mean preoperative myopia of 7794 eyes that underwent LASIK in a LASIK center was 4.8 6 2.4 D.34 Another possible bias is the interdevice difference in refractive surgeries. Because our study period runs from 2007 to 2012, it is possible that some of our patients received refractive surgeries using newer technology such as femtosecond laser-assisted LASIK, which may not require as much suction power to make a corneal flap as does the classic microkeratome-assisted LASIK. Finally, both the R (þ) and the R () group in the present study did not include highly myopic eyes with posterior staphyloma. Thus, it is not certain whether our study findings could be applicable to highly myopic eyes or pathologically myopic eyes. Despite the limitations, we believe that our study has shown clearly that there was no notable difference in the clinical features of rhegmatogenous RD between the R (þ) group and the R () group, at least in myopes without posterior staphyloma. In conclusion, the characteristics of retinal breaks and rhegmatogenous RD in patients with prior LASIK were not significantly different from those with prior LASEK or myopic patients without prior refractive surgery. Myopia itself, rather than refractive surgery, may have a greater impact on the development of rhegmatogenous RD in myopic patients with previous refractive surgery.
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ALL AUTHORS HAVE COMPLETED AND SUBMITTED THE ICMJE FORM FOR DISCLOSURE OF POTENTIAL CONFLICTS OF INTEREST. Design and conduct of study (H.M.K., K.H.L., C.S.L.); Collection of data (H.M.K., H.J.P.); Management, analysis and interpretation of data (H.M.K., C.S.L.); and Preparation, review and approval of the manuscript (H.M.K., C.S.L., S.C.L.). The authors thank Dong-Su Jang, B,A. (Research Assistant, Department of Anatomy, Yonsei University College of Medicine, Seoul, South Korea), for his help with the figures.
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17. Aras C, Ozdamar A, Karacorlu M, et al. Retinal detachment following laser in situ keratomileusis. Ophthalmic Surg Lasers 2000;31(2):121–125. 18. Arevalo JF, Ramirez E, Suarez E, et al. Rhegmatogenous retinal detachment in myopic eyes after laser in situ keratomileusis: frequency, characteristics, and mechanism. J Cataract Refract Surg 2001;27(5):674–680. 19. Flaxel CJ, Choi YH, Sheety M, Oeinck SC, Lee JY, McDonnell PJ. Proposed mechanism for retinal tears after LASIK: an experimental model. Ophthalmology 2004; 111(1):24–27. 20. Arevalo JF, Lasave AF, Torres F, Suarez E. Rhegmatogenous retinal detachment after LASIK for myopia of up to 10 diopters: 10 years of follow-up. Graefes Arch Clin Exp Ophthalmol 2012;250(7):963–970. 21. Schepens CL, Hartnett ME, Hirose H. Part 1: Basic considerations. In: Schepens’ retinal diseases and allied diseases. 2nd ed. Boston, MA: Butterworth-Heinemann; 2000:27–96. 22. Goffstein R, Burton TC. Differentiating traumatic from nontraumatic retinal detachment. Ophthalmology 1982; 89(4):361–368. 23. Zion VM, Burton TC. Retinal dialysis. Arch Ophthalmol 1980; 98(11):1971–1974. 24. Smiddy WE, Green WR. Retinal dialysis: pathology and pathogenesis. Retina 1982;2(2):94–116. 25. Krueger RR, Krasinski JS, Radzewicz C, et al. Photography of shock waves during excimer laser ablation of the cornea: effect of helium gas on propagation velocity. Cornea 1993; 12(4):330–334. 26. Siano S, Pini R, Gobbi PG, et al. Intraocular measurements of pressure transients induced by excimer laser ablation of the cornea. Lasers Surg Med 1997;20(4):416–425. 27. Sporl E, Gruchmann T, Genth U, et al. Laser-induced pressure waves in the eye: propagation characteristics. Ophthalmologe 1997;94(8):578–582. 28. Mitry D, Fleck BW, Wright AF, Campbell H, Charteris DG. Pathogenesis of rhegmatogenous retinal detachment: predisposing anatomy and cell biology. Retina 2010;30(10):1561–1572. 29. Kirker GEM, McDonald DJ. Peripheral retinal degeneration in high myopia. Can J Ophthalmol 1971;6(1):58–61. 30. Celorio JM, Pruett RC. Prevalence of lattice degeneration and its relation to axial length in severe myopia. Am J Ophthalmol 1991;111(1):20–23. 31. Grossniklaus HE, Green WR. Pathologic findings in pathologic myopia. Retina 1992;12(2):127–133. 32. Akiba J. Prevalence of posterior vitreous detachment in high myopia. Ophthalmology 1993;100(9):1384–1388. 33. Morita H, Funata M, Tokoro T. A clinical study of the development of posterior vitreous detachment in high myopia. Retina 1995;15(2):117–124. 34. Kohnen T, Koch DD. SpringerLink. Cataract and refractive surgery. Berlin, Heidelberg, Germany: Springer-Verlag Berlin Heidelberg; 2005:189–201.
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Biosketch Hae Min Kang, MD, graduated from Yonsei University College of Medicine in 2007 where she completed internship and residency in 2012. During residency, she received the ARVO Travel grant awards in 2011. After completion of 2-year of retinal fellowship in Yonsei University Severance Hospital, Seoul, South Korea, she is now in charge of retinal division, Incheon International St. Mary’s Hospital, Incheon, South Korea. Her research interests include age-related macular degeneration, especially polypoidal choroidal vasculopathy, and myopic choroidal neovascularization.
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Biosketch Christopher Seungkyu Lee, MD, obtained his bachelor’s degree in Molecular Cell Biology at the University of California at Berkeley, U.S.A. and medical degree at the Yonsei University College of Medicine, Seoul, Korea. After completing his residency and fellowship at the department of ophthalmology of the Yonsei University, he currently serves as a vitreoretinal specialist and an assistant professor at Shinchon Severance Hospital, Yonsei University College of Medicine. Dr Lee’s area of research interest includes macular disorders, uveitis, and intraocular tumors.
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To evaluate the characteristics of rhegmatogenous retinal detachment (RD) in patients with previous laser in situ keratomileusis (LASIK) and compare them to RD in patients with previous laser assisted subepithelial keratomileusis (LASEK) and myopic patients with no previous refractive surgery. DESIGN: Retrospective, comparative case series. METHODS: In 106 eyes of 106 patients with RD, patients with previous refractive surgery included 21 eyes after LASIK and 13 eyes after LASEK; 72 myopic patients with refractive errors of L3.0 diopters or less were grouped as the R (L) group. Characteristics of RD included distribution of RD and associated retinal breaks, location and number of retinal breaks, presence of lattice degeneration, and axial lengths. RESULTS: The mean interval between refractive surgery and the onset of rhegmatogenous RD was 63.7 ± 43.5 months, occurring across a broad spectrum of time intervals. There were no significant differences among the LASIK group, the LASEK group, and the R (L) group in axial length (26.8 mm vs 26.4 mm vs 26.9 mm, respectively); in mean number of retinal holes/tears, (2.1/1.5, 0.9/1.4, 1.5/1.6, respectively); or in the presence of lattice degeneration (52.4% vs 46.2% vs 43.1%, respectively). Distribution of RD and associated retinal breaks were also not significantly different; retinal holes and tears were more prevalent in the temporal quadrants, and inferotemporal quadrants were the most commonly detached areas in both the LASEK and LASIK groups and in the R (L) group. CONCLUSIONS: Myopia is a well-known risk factor for rhegmatogenous RD and may contribute more to the development of RD in myopic patients after refractive surgery, rather than refractive surgery itself. (Am J Ophthalmol 2014;157:666–672. Ó 2014 by Elsevier Inc. All rights reserved.)
Accepted for publication Dec 2, 2013. From the Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea (H.M.K., C.S.L., H.J.P., K.H.L., S.H.B., H.J.K., S.C.L.); Department of Ophthalmology, Incheon International St. Mary’s Hospital, Incheon, South Korea (H.M.K.). Inquiries to Christopher Seungkyu Lee, Department of Ophthalmology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, South Korea; e-mail: [email protected]
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Ó
2014 BY
R
HEGMATOGENOUS RETINAL DETACHMENT (RD),
the most common type of RD, is caused by liquefied vitreous passing through a retinal break into the subretinal space, separating the neurosensory retina from the retinal pigment epithelium.1,2 Fundamental mechanisms leading to rhegmatogenous RD are largely unknown. The formation of retinal breaks is often preceded by vitreoretinal degeneration, the cause of which is unclear. One of the factors strongly associated with rhegmatogenous RD is myopia.3–5 Low myopes (0.75 to 2.75 diopters [D]) show an odds ratio of 3.14 for RD, and the odds ratio was shown to rise steeply with increasing myopic refractive errors in the Japanese population.4 Increased vitreous liquefaction, earlier posterior vitreous detachment, and higher incidence of vitreoretinal degeneration such as lattice degeneration are thought to be attributable to the higher prevalence in rhegmatogenous RD in myopes.2 Refractive surgeries, such as laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratomileusis (LASEK), have been popularized for correction of low to moderate myopia.6,7 Vision-threatening posterior segment complications can occur after refractive surgeries; they include macular hemorrhages, macular holes, and rhegmatogenous RD.8–14 The reported incidence of rhegmatogenous RD in those with histories of LASIK is not high, ranging from 0.033% to 0.25%.11,15–17 However, many have regarded a suction ring application during LASIK to be a potential risk factor for rhegmatogenous RD because this procedure may induce vitreous traction and detachment resulting from sudden decompression of the eye.18,19 A previous study found that retinal breaks were more commonly located in the inferotemporal quadrant in rhegmatogenous RD after LASIK.20 Whether this feature is characteristic of rhegmatogenous RD after LASIK is unclear because this finding was not compared to rhegmatogenous RD without prior LASIK. Herein, we studied the characteristics of rhegmatogenous RD in patients with previous LASIK and compared them to both rhegmatogenous RD in myopic patients with no previous refractive surgeries and to rhegmatogenous RD in patients with previous LASEK, which does not require a suction ring application, unlike LASIK.
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0002-9394/$36.00 http://dx.doi.org/10.1016/j.ajo.2013.12.004
FIGURE 1. Distribution of the intervals between refractive surgery and the onset of rhegmatogenous retinal detachment in patients with prior refractive surgery. Note that the mean interval between refractive surgery and rhegmatogenous RD onset was 63.7 ± 43.5 months.
METHODS ENROLLMENT OF STUDY SUBJECTS:
We retrospectively reviewed 106 eyes of 106 patients who fulfilled the inclusion criteria at the Vitreoretinal Service Clinic of Yonsei University Medical Center between March 2007 and March 2012. This retrospective, comparative case series was performed with the approval of the Institutional Review Board of Yonsei University College of Medicine and conducted in accordance with the tenets of the Declaration of Helsinki. Inclusion criteria were patients with (1) nontraumatic rhegmatogenous RD who underwent surgical repair; (2) no previous surgical history other than corneal laser refractive surgery for the study group; and (3) 3.0 D or lower myopia without previous refractive surgery for the control group. Patients with concomitant ocular diseases, such as diabetic retinopathy, myopic choroidal neovascularization or uveitis at the time of surgery were excluded. The patients included 34 eyes of 34 patients who had histories of refractive surgery before the onset of rhegmatogenous RD (21 eyes after LASIK and 13 eyes after LASEK), and they were grouped as the refractive surgery group (R [þ] group). The remaining 72 myopic patients without previous refractive surgery were grouped as the nonrefractive surgery group (R [] group), or the control group. The control group was selected to include moderately myopic patients who would be typical candidates for LASIK or LASEK. Because of a lack of information about refractive errors before refractive surgery for the R (þ) group, the axial lengths of the affected eyes were used to confirm and compare the degrees of myopia between the R (þ) and the R () groups. No patient in VOL. 157, NO. 3
the R (þ) group showed myopic posterior staphyloma, so highly myopic patients with posterior staphyloma were excluded in the R () group. EXAMINATION: All patients received complete ocular examinations, including best-corrected visual acuity (BCVA), color fundus photography and ultrasonography. Follow-up visits were arranged in general at 1 week and 1 month after each surgery. Subsequent 3- to 6-month examinations were performed; they included BCVA and dilated fundus examinations with an indirect ophthalmoscope. STATISTICAL ANALYSIS: Patients’ characteristics were retrieved from their medical charts, including age at refractive surgery and development of rhegmatogenous RD, sex, and axial lengths (mm). BCVA by decimal visual acuity charts were converted into logarithm of the minimum angle of resolution (logMAR) values for statistical analysis. We evaluated the characteristics of RD, including numbers and locations of retinal tears and holes and the presence of lattice degeneration. In addition, rhegmatogenous RD extent (involved quadrants), location of the detached retina, and status of the macula (detached labeled as off and attached as on) were investigated by reviewing the operation notes. The rhegmatogenous RD eyes were also classified as 1 of 3 types: equatorial, oral or macular.21 SPSS Statistics 18.0 software for Windows (IBM, Somers, NY, USA) was used for statistical analysis. The Kolmogrov-Smirnov test was used to confirm normal distribution of the study population. For comparison of the eyes with and without prior refractive surgery, the Student t test
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TABLE 1. Comparison of Characteristics of Rhegmatogenous Retinal Detachment between Laser in situ Keratomileusis (LASIK) and Laser-Assisted Subepithelial Keratomileusis (LASEK) Groups
Retinal breaks Retinal hole only Retinal tear only Both Mean number of retinal holes (per eye) Mean number of retinal tears (per eye) Lattice degeneration Macula attached at baseline Location of retinal holes (quadrants) Superotemporal Superonasal Inferotemporal Inferonasal Location of retinal tears (quadrants) Superotemporal Superonasal Inferotemporal Inferonasal Detached area Superonasal quadrants Superotemporal quadrants Inferonasal quadrants Inferotemporal quadrants Inferior half Superior half Temporal half Nasal half Total
P valuea,b
LASIK group (n ¼ 21)
LASEK group (n ¼ 13)
11 (52.4%) 5 (23.8%) 5 (23.8%) 2.1 6 2.1
8 (61.5%) 4 (30.8%) 1 (7.7%) 0.9 6 0.7
.054a
1.5 6 0.6
1.4 6 0.5
.492a
11 (52.4%) 8 (38.1%)
6 (46.2%) 5 (38.5%)
.658b .929b .765b
5 (31.3%) 1 (6.3%) 8 (50.0%) 2 (12.4%)
1 (11.1%) 2 (22.2%) 6 (66.7%) 0 (0.0%)
2 (20.0%) 3 (30.0%) 4 (40.0%) 1 (10.0%)
3 (60.0%) 0 (0.0%) 2 (40.0%) 0 (0.0%)
.399b
.366b
.398b 2 (9.5%) 2 (9.5%)
1 (7.6%) 4 (30.8%)
1 (4.8%) 0 (0.0%) 7 (33.3%) 5 (23.8%) 3 (14.3%) 0 (0.0%) 1 (4.8%)
0 (0.0%) 3 (23.1%) 3 (23.1%) 2 (15.4%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
a
Mann-Whitney U test for continuous variables. Wilcoxon signed-rank test for categorical variables. P < 0.05 was set for clinical significance.
b
for continuous variables and the x2 test for categorical variables were used. For subgroup analysis, nonparametric analysis was used: the Mann-Whitney U test for continuous variables and the Wilcoxon signed-rank test for categorical variables. Results with P less than 0.05 were considered statistically significant.
RESULTS CHARACTERISTICS OF THE PATIENTS: In 106 eyes of 106 patients, 34 eyes (34 patients) had histories of
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refractive surgery, whereas 72 eyes (72 patients) with myopia had had no previous refractive surgery. Of the patients, 56 (52.8%) were male, including 14 males with prior refractive surgery and 42 patients with myopic RD. The mean follow-up period after retinal reattachment surgery was 13.5 6 4.6 months. All patients achieved retinal reattachment after surgery, among which 10 eyes (9.4%) underwent surgical repair of redetached retina. After RD surgery, mean BCVA improved from 0.76 6 0.88 logMAR (Snellen equivalent 20/115) at baseline to 0.38 6 0.67 logMAR (Snellen equivalent 20/47) at the last follow-up visits (P ¼ .001). The mean age at rhegmatogenous RD onset was 33.6 6 9.8 years and mean symptom duration was 3.1 6 6.8 weeks in symptomatic cases. In all patients, 19 eyes of 19 patients had no visual symptoms, and rhegmatogenous RD was diagnosed during a routine fundus examination. Of 34 eyes with prior refractive surgery, 21 eyes (61.8%) underwent LASIK and 13 eyes (38.2%) received LASEK. The mean age at the time of refractive surgery was 29.6 6 7.8 years, and the mean interval between refractive surgery and rhegmatogenous RD onset was 63.7 6 43.5 months. None of the patients with prior refractive surgery received any treatment with barrier laser at the time of refractive surgery. The distribution of patients according to the interval between refractive surgery and rhegmatogenous RD onset is shown in Figure 1. The mean refractive errors in 72 patients in the R () group were 4.5 6 4.0 D in affected eyes and 4.6 6 4.4 D in unaffected eyes. COMPARISON BETWEEN EYES WITH PRIOR LASIK AND LASEK: The mean age at the time of refractive surgery
was 31.5 6 7.8 years in the LASIK group and 26.5 6 6.9 years in the LASEK group (P ¼ .063). The mean age at onset of rhegmatogenous RD was older in the LASIK group (38.4 6 8.8 years) than in the LASEK group (28.9 6 8.2 years) (P ¼ .003). The mean interval between refractive surgery and onset of rhegmatogenous RD was longer in the LASIK group (85.8 6 37.9 months) than in the LASEK group (28.1 6 23.9 months) (P ¼ .001). The mean axial length was not significantly different in the 2 groups: 26.8 6 1.7 mm in the LASIK group and 26.4 6 0.8 mm in the LASEK group (P ¼ .398). Mean BCVA at baseline was 0.75 6 0.73 logMAR (Snellen equivalent 20/112) in the LASIK group and 0.69 6 0.42 logMAR (Snellen equivalent 20/97) in the LASEK group (P ¼ .425). Mean BCVA improved in both groups after RD surgery when compared with baseline: 0.28 6 0.21 logMAR (Snellen equivalent 20/38) in the LASIK group, and 0.13 6 0.26 logMAR (Snellen equivalent 20/26) in the LASEK group (P ¼ .210). There were no statistically significant differences between the 2 groups in characteristics of rhegmatogenous RD and retinal breaks (Table 1). The distribution of retinal breaks of each group is shown in Figure 2.
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FIGURE 2. Distribution of retinal holes and retinal tears associated with rhegmatogenous retinal detachment after refractive surgery. Location of retinal breaks was assessed using the operation at the time of retinal reattachment surgery. (Left) Eyes with prior laser in situ keratomileusis (LASIK). (Right) eyes with prior laser-assisted subepithelial keratomileusis (LASEK). Note that the round figure represents a retinal hole, and the crescent shape represents a retinal tear.
COMPARISON BETWEEN EYES WITH PRIOR LASIK AND MYOPIC EYES WITH NO PREVIOUS REFRACTIVE SURGERY:
We compared the eyes with prior LASIK (LASIK group) and myopic eyes without previous refractive surgery (R [] group). The mean age at rhegmatogenous RD onset was older in the LASIK group (38.4 6 8.8 years) than in the R () group (33.1 6 9.9 years) (P ¼ .029). The mean axial length was 26.83 6 1.73 mm in the LASIK group and 26.9 6 1.8 mm in the R () group (P ¼ .893). The mean BCVA at baseline was 0.75 6 0.73 logMAR (Snellen equivalent 20/112) in the LASIK group, and 0.85 6 0.96 logMAR (Snellen equivalent 20/141) in the R () group (P ¼ .662). Mean BCVA at last visit was 0.28 6 0.21 logMAR (Snellen equivalent 20/38) in the LASIK group and 0.41 6 0.38 logMAR (Snellen equivalent 20/51) in the R () group (P ¼ .106). The distribution of rhegmatogenous RD and associated retinal breaks were not significantly different in the 2 groups, as shown in Table 2.
DISCUSSION WE COMPARED THE CLINICAL CHARACTERISTICS OF RHEG-
matogenous RD and associated retinal breaks between myopic patients with and without previous refractive surgery and found no significant difference. In the R (þ) group, retinal holes and tears were located predominantly in the temporal quadrants (80.0% and 73.3%, respectively). These findings are compatible with a previous study in which the predominant location of retinal breaks was reported in the temporal quadrants.20 These authors explained that extra pressure due to the temporal handle of surgical microkeratomes during LASIK might be responsible for the temporal predominance of retinal breaks.20 However, in our study, retinal holes and tears in the R VOL. 157, NO. 3
() group were more prevalent in the temporal quadrants (76.9% and 51.2%, respectively) than in the nasal quadrants. The inferotemporal quadrants were the most commonly involved areas of RD in the LASIK group (52.4%), which was also consistent with a previous study.20 However, the R () group also showed the inferotemporal quadrants as being the most commonly involved area of RD (66.7%). Common development of retinal breaks in the temporal quadrants, especially in the interotemporal quadrants, may explain the frequent finding of temporal rhegmatogenous RD. The comparison of rhegmatogenous RD features between LASIK eyes and LASEK eyes showed no significant differences except in the mean numbers of retinal holes per eye. Those with prior LASIK showed significantly more retinal holes per eye than those with prior LASEK. This may be an incidental finding, rather than a characteristic finding of RD after LASIK because there was no significant difference in the mean number of retinal holes and tears compared to patients in the R () group. Retinal breaks in the LASEK group had temporal predominance (77.8% of retinal holes and 100% of retinal tears); similarly, rhegmatogenous RD in the LASEK group commonly involved the interotemporal quadrants (46.2%). These characteristics of the LASEK group were similar to those of the LASIK group and the R () group. Previous studies have paid particular attention to rhegmatogenous RD after LASIK because the application of the suction rings during the LASIK procedure may induce anomalous vitreous detachment and work as a causative factor for the development of rhegmatogenous RD.18,19 However, rhegmatogenous RD could develop even after LASEK, and we found that the characteristics of RD and associated retinal breaks were not significantly different in eyes after LASIK and eyes after LASEK. Moreover, the mean interval between refractive surgery and the onset of rhegmatogenous RD was actually longer in the LASIK group than in the
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TABLE 2. Comparison of Characteristics of Rhegmatogenous Retinal Detachment (RD) Between the Eyes With (Refractive Group) and Those Without (Nonrefractive Group) Prior to Refractive Surgery LASIK group (n ¼ 21)
Mean number of retinal holes 2.1 6 2.1 (per eye) Mean number of retinal tears 1.5 6 0.6 (per eye) Retinal breaks Retinal hole only 11 (52.4%) Retinal tear only 5 (23.8%) Both 5 (23.8%) Macula attached at baseline 8 (38.1%) Lattice degeneration 11 (52.4%) Location of retinal holes (quadrant) Superotemporal 5 (31.3%) Superonasal 1 (6.3%) Inferotemporal 8 (50.0%) Inferonasal 2 (12.4%) Location of retinal tears (quadrant) Superotemporal 2 (20.0%) Superonasal 3 (30.0%) Inferotemporal 4 (40.0%) Inferonasal 1 (10.0%) Detached area Superonasal quadrant 2 (9.5%) Superotemporal quadrant 2 (9.5%) Inferonasal quadrant 1 (4.8%) Inferotemporal quadrant 0 (0.0%) Inferior half 7 (33.3%) Superior half 5 (23.8%) Temporal half 3 (14.3%) Nasal half 0 (0.0%) Total 1 (4.8%)
Nonrefractive group (n ¼ 72)
P valuea,b
1.5 6 1.8
.237a
1.6 6 0.7
.492a .399b
35 (48.6%) 27 (37.5%) 10 (13.9%) 30 (41.7%) 31 (43.1%)
.729b .578b .765b
13 (25.0%) 4 (7.7%) 27 (51.9%) 8 (15.4%) .366b 10 (24.4%) 14 (34.2%) 11 (26.8%) 6 (14.6%) .525b 2 (2.8%) 8 (11.0%) 1 (1.4%) 9 (12.5%) 21 (29.2%) 10 (13.9%) 13 (18.1%) 3 (4.2%) 5 (6.9%)
a
Student t test for continuous variables. x test for categorical variables. P < 0.05 was set for clinical significance.
b 2
LASEK group. If vitreous traction and detachment from a suction ring application were significant factors in rhegmatogenous RD development, one would expect to find a shorter interval to rhegmatogenous RD in eyes after LASIK than in eyes after LASEK, which does not require a suction ring application. A suction ring is placed just behind the limbus with a vacuum device to firm the cornea during LASIK. When the suction ring induces an increase in intraocular pressure and is suddenly released, the anterior segment is rapidly drawn into the vacuum chamber, with its shape changing rapidly.19 During this process, all structures posterior to the suction ring are compressed and decompressed in sequence, possibly leading to acute vitreoretinal traction 670
at the vitreous base and posterior pole.19,21 In this respect, rhegmatogenous RD after LASIK may be regarded as a traumatic RD. However, no patients with rhegmatogenous RD after LASIK or LASEK have shown oral-type RD, which is characteristic after blunt trauma.21,22 This may be due to differences in the mechanism of compression and decompression processes between LASIK and blunt trauma. In blunt trauma, equatorial expansion of the eyeball is an active process, resulting from the force exerted on the anterior portion of the eye.21,23,24 Decompression, then, follows to resume the normal shape of the eyeball.21–24 Conversely, the suction-ring application results in elongation of the eyeball. The equatorial expansion results from a passive decompression process. In other words, equatorial expansion results from active compression during blunt trauma, whereas it results from passive decompression during a suction ring application (Fig. 3). Active equatorial expansion during blunt trauma can result in oral-type RD, including dialysis and giant retinal tears.21–24 Passive equatorial expansion from a suction ring application may not pose a significant risk for inducing vitreous detachment and RD. Another previously proposed mechanism for rhegmatogenous RD after refractive surgeries is shock waves generated during excimer laser treatment.9,25–27 These waves can possibly result in mechanical stress on the eye and affect structures in the posterior segments. Although it is quite possible that any impact to the eye may influence the vitreoretinal dynamics and cause retinal breaks, contribution of shock waves from excimer laser may not be significant because there was no significant difference in the RD features between the R (þ) group and the R () group. Rather than the impact of refractive surgery, our findings suggest that myopia and the associated changes of the eyes may contribute more to the development of RD in patients after refractive surgery. It is well known that myopia itself is a strong risk factor for RD.3–5 Refraction was identified as the major identifiable risk factor for RD, with an adjusted odds ratio in the range of 1 D to 3 D of 4.4, increasing to 9.9 in the range of 3 D to 8 D.5 For any _1 D), the corrected odds ratio was degree of myopia (< 7.5.5 The odds ratio rose steeply with increasing myopia to greater than 80 for myopia in excess of 15 D.4 In myopic eyes, posterior vitreous detachment occurs early, lattice degeneration is more common, and the retina is thinner than in emmetropes, leading to a more common occurrence of rhegmatogenous RD.3,28–33 Development of vitreous liquefaction is more extensive and occurs earlier in myopic eyes, and it is significantly correlated with an axial length of greater than 30 mm.32,33 Because eyes that have undergone refractive surgery are myopic, they already are at risk for development of rhegmatogenous RD. The mean interval of 63.7 6 43.5 months between refractive surgery and onset of RD was generally longer in this study than in previous studies, which showed a mean
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FIGURE 3. Postulated vitreoretinal changes due to blunt trauma (Top) and laser in situ keratomileusis (LASIK) (Bottom). (Top) In blunt trauma, equatorial expansion of the eyeball is an active process, resulting from the force exerted on the anterior portion of the eye. Decompression, then, follows to resume the normal shape of the eyeball. (Bottom) During LASIK, a suction ring application results in an anterior-posterior elongation of the eyeball. Equatorial expansion results from a passive decompression process after release of the suction ring. Then the shape of the eyeball is normalized.
interval of between 12 and 31 months.9–11,15,16,18,20 However, previous studies also showed variations in the intervals between refractive surgery and the onset of RD.9–11,15,16,18,20 This variability in the interval between refractive surgery and RD onset may imply that refractive surgery may not contribute any more significantly to the development of RD than myopia itself. There are several limitations in this study. This was a retrospective study with a relatively small study population, which may affect the statistical significance of our findings. However, given the low incidence of rhegmatogenous RD after refractive surgery and the variable onset interval, a prospective study with a sufficient number of subjects for adequate statistical power is virtually nonexecutable. Another drawback of the present study is the lack of data concerning refractive error in patients involved in the study before refractive surgeries. Vitreoretinal abnormalities become more likely with increasing myopia,3–5 so it is important to include patients with similar degrees of myopia for comparative study. However, the mean axial lengths of the R (þ) group and the R () group were the same. There was no difference in axial lengths between LASIK eyes and LASEK eyes, either. Furthermore, the mean refractive error of the R () group was 4.5 6 4.0 D, which may represent the mean refractive error in patients who would
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be potential candidates for refractive surgery; the mean preoperative myopia of 7794 eyes that underwent LASIK in a LASIK center was 4.8 6 2.4 D.34 Another possible bias is the interdevice difference in refractive surgeries. Because our study period runs from 2007 to 2012, it is possible that some of our patients received refractive surgeries using newer technology such as femtosecond laser-assisted LASIK, which may not require as much suction power to make a corneal flap as does the classic microkeratome-assisted LASIK. Finally, both the R (þ) and the R () group in the present study did not include highly myopic eyes with posterior staphyloma. Thus, it is not certain whether our study findings could be applicable to highly myopic eyes or pathologically myopic eyes. Despite the limitations, we believe that our study has shown clearly that there was no notable difference in the clinical features of rhegmatogenous RD between the R (þ) group and the R () group, at least in myopes without posterior staphyloma. In conclusion, the characteristics of retinal breaks and rhegmatogenous RD in patients with prior LASIK were not significantly different from those with prior LASEK or myopic patients without prior refractive surgery. Myopia itself, rather than refractive surgery, may have a greater impact on the development of rhegmatogenous RD in myopic patients with previous refractive surgery.
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ALL AUTHORS HAVE COMPLETED AND SUBMITTED THE ICMJE FORM FOR DISCLOSURE OF POTENTIAL CONFLICTS OF INTEREST. Design and conduct of study (H.M.K., K.H.L., C.S.L.); Collection of data (H.M.K., H.J.P.); Management, analysis and interpretation of data (H.M.K., C.S.L.); and Preparation, review and approval of the manuscript (H.M.K., C.S.L., S.C.L.). The authors thank Dong-Su Jang, B,A. (Research Assistant, Department of Anatomy, Yonsei University College of Medicine, Seoul, South Korea), for his help with the figures.
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Biosketch Hae Min Kang, MD, graduated from Yonsei University College of Medicine in 2007 where she completed internship and residency in 2012. During residency, she received the ARVO Travel grant awards in 2011. After completion of 2-year of retinal fellowship in Yonsei University Severance Hospital, Seoul, South Korea, she is now in charge of retinal division, Incheon International St. Mary’s Hospital, Incheon, South Korea. Her research interests include age-related macular degeneration, especially polypoidal choroidal vasculopathy, and myopic choroidal neovascularization.
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Biosketch Christopher Seungkyu Lee, MD, obtained his bachelor’s degree in Molecular Cell Biology at the University of California at Berkeley, U.S.A. and medical degree at the Yonsei University College of Medicine, Seoul, Korea. After completing his residency and fellowship at the department of ophthalmology of the Yonsei University, he currently serves as a vitreoretinal specialist and an assistant professor at Shinchon Severance Hospital, Yonsei University College of Medicine. Dr Lee’s area of research interest includes macular disorders, uveitis, and intraocular tumors.
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