AMERICAN J O U R N A L OF OPHTHALMOLOGY V O L U M E 81
MAY,
1976
NUMBER 5
PARS PLANA VITRECTOMY FOR T H E MANAGEMENT O F SEVERE DIABETIC RETINOPATHY M A R K S. M A N D E L C O R N , M.D., G E O R G E B L A N K E N S H I P , AND R O B E R T M A C H E M E R , M.D. Miami,
M.D.,
Florida
Since April 1970, approximately 900 pars plana vitrectomies have been per formed here. About 50% have been for the late complications of proliferative diabet ic retinopathy. This report describes the preoperative, operative, and postopera tive anatomical findings and visual func tion of 100 consecutive cases with post operative follow-up examinations of at least five months. MATERIAL AND METHODS
Between May 1972 and November 1973, pars plana vitrectomies 1 were per formed by one of us (R.M.) on 105 con secutive eyes of patients who had devel oped late complications of diabetic reti nopathy. In this study an attempt was made to observe all patients for at least six months or more, but because of schedul ing difficulties, a few patients were exam ined five months postoperatively. When follow-up information was available after six months, this was included to provide better information about the long-term results of this operative procedure. FiftyFrom the Bascom Palmer Eye Institute, Depart ment of Ophthalmology, University of Miami School of Medicine, and the Veterans Administra tion Hospital, Miami, Florida. This study was sup ported in part by Public Health Service research grant EY-00841; by the Veterans Administration Hospital, Miami, Florida; and by the Florida Lions Eye Bank, Inc., Miami, Florida. Dr. Mandelcorn was a fellow of the Medical Research Council of Canada. Reprint requests to Robert Machemer, M.D., Bas com Palmer Eye Institute, P.O. Box 520875, Biscayne Annex, Miami, F L 33152.
seven of the eyes were examined between five and seven months after surgery, 29 were examined between eight and 12 months postoperatively, and the remain ing 14 eyes were examined more than one year after surgery. The duration of follow-up ranged from five to 30 months with a median of seven months. Five patients died before the six-month post operative examination could be per formed, leaving 100 cases for this study. An attempt was made to obtain infor mation on 220 different questions or po tential observations from each case re garding the patients' general characteris tics, visual function, and ophthalmic findings. These data were recorded at the preoperative examination, operative pro cedure, and postoperatively at IV2 weeks and at least five months later. Unfortu nately, some of the data were missing due to an inability to obtain complete followup information on cases when patients were unable to return for the planned six-month postoperative examination. Of the 100 patients, 64 returned as requested and had complete examinations, and in formation on the other 36 cases was gath ered from other ophthalmologists. Also, some of the data were occasionally miss ing due to incomplete records. Structures located posterior to opaque material in the optical media could not be examined preoperatively, but in these instances the operative findings were used. Missing or incomplete data were recorded as no in formation.
561
562
AMERICAN JOURNAL OF OPHTHALMOLOGY
The information was transferred to computer cards for analysis by two of us (M.S.M. and G.B.). Ten randomly select ed cases were independently coded to evaluate potential bias, and the interpre tation of the information was essentially identical. The data and correlations were analy zed using the chi square test for statistical significance. Probability values achieved by the chi square test on 2 X 2 tables of less than 0.01 were not considered signif icant. Only statistically significant differ ences will be mentioned. RESULTS
General characteristics—The 100 cases included 65 men and 35 women, 54 right and 46 left eyes, and the median age at surgery was 51 years with a range of 20 to 76 years. All patients were known to be diabetic and the median duration of es tablished diabetes mellitus at surgery was 20 years with a range from less than one year to 43 years. The median duration of visual symptoms relatable to diabetic retinopathy in the operated eye was three years with a range of less than one year to 18 years. Since it was thought that the vitrectomy procedure would only be jus tified if it resulted in major visual im provement, the visual acuities were grouped into broad categories: 1: reading vision, 6/5 to 6/12 (20/15 to 20/40); 2: decreased visual acuity but not legal blindness, 6/15 to 6/60 (20/50 to 20/200); 3: ambulating visual acuity, 6/90 (20/300 to counting fingers); 4: minimal visual function, hand movements to light per ception; and 5: no visual function. In addition to their diabetes, 29 pa tients had systemic hypertension, eight had cardiac disease, 14 had renal disease, and 35 had other diabetic problems (neu ropathies, decreased peripheral circula tion, and the like). Insulin was used by 80 patients, 17 were managed with oral hy poglycémie agents, two were managed by
MAY, 1976
diet alone, and one patient had had a hypophysectomy. Twenty-one eyes had been treated with photocoagulation before preoperative evaluation. Preoperative visual function—The pre operative visual acuities of most eyes were less than counting fingers (Table 1). Most eyes had dense vitreous hemorrhag es and occasional posterior traction reti nal detachments. Eyes in Groups 1 and 2 only had proliferative tissue and minor vitreous hemorrhages, and had vitrectomies to reduce vitreous traction and mini mize future hemorrhages. Subjective visual function testing uti lized the perception of the entoptic phe nomenon. 1 The perception of red color produced with a red filter, pen light, and Maddox rod were tested at a distance of 1 meter. Confrontation visual fields were used to evaluate the level of peripheral vision. Pupillary responses were exam ined to obtain a more objective measure ment of the visual function (Table 2). Traditionally the perception of both the entoptic phenomenon and color were thought to represent macular function, but the discrepancy between the positive responses of these two tests suggested that color perception reflects function of peripheral cones as well. The Maddox rod perception was frequently absent despite the presence of color perception. Most patients had retained some vision in each of the peripheral quadrants. Patients with severe diabetic retinopathy tended to TABLE 1 PREOPERATIVE VISUAL ACUITIES
Groups 1 2 3 4 5 Total
Visual Acuity 6/5-6/12 6/15-6/60 6/90-CF HM-LP NLP
No. of Eyes 1 5 24 70 0 100
PARS PLANA VITRECTOMY
VOL. 81, NO. 5
563
TABLE 2 VISUAL FUNCTION TEST RESULTS
Postoperative, 5 mos or more
Preoperative Results Absent
Present Entoptic phenomena Red color Maddox rod* Full peripheral visual field Normal pupil response
No Information
Present
Absent
No Information
20
76
4
27
40
33
76 33 74
15 49 18
9 18 8
34 34 39
25 29 29
41 37 32
20
64
16
7
52
41
* E x a m i n a t i o n a d d e d t o r o u t i n e e v a l u a t i o n after s t u d y h a d s t a r t e d .
have abnormal pupillary responses. In addition to afferent conductive defects, the response also evaluated the influence of opacities in the optic media and dam age to the iris tissue. Preoperative anterior segment findings—The anterior segments were exam ined by slit-lamp biomicroscopy. No sig nificant corneal abnormalities were ob served (Table 3). When flare and cells were found in eyes with vitreous hemorrhages, they were thought to be the breakdown products of blood, rather than actual inflammation. However, when there was severe flare, it was usually associated with extensive rubeosis iridis. These eyes were consid-
ered inoperable, as were eyes with exten sive rubeosis iridis and neovascular glau coma. Eight eyes with mild rubeosis iridis around the pupillary margins and normal intraocular pressures were in cluded. The prevalence of cataracts and aphakia is shown in Table 4. As expected in diseased diabetic eyes, most lenses had cataractous changes and many were al ready aphakic. The preoperative presence of severe nuclear sclerosis complicated the vitrectomy procedure to such a degree that in most cases, a routine ab externo cataract TABLE 4 LENS FINDINGS
TABLE 3 ANTERIOR CHAMBER FINDINGS
Preoperative Flare Absent Moderate (1 - 2+) Severe (3 - 4+) No information Total Cells Absent Moderate (1 - 2+) Severe (3 - 4+) No information Total
75 25 0 0 100 89 10 1 0 100
Postoperative, 5 mos or more 53 22 11 14 100 63 13 9 15 100
Preoperative
Postoperative, 5 mos or more
Nuclear sclerosis Absent Moderate (1 - 2 + ) Severe (3 - 4+) No information Total
29 52 2 0 83
9 3 2 2 16
Posterior subcapsular cataract Absent Moderate (1 - 2 + ) Severe (3 - 4+) No information Total
11 42 29 1 83
4 7 3 2 16
Aphakia
17
84
564
AMERICAN JOURNAL OF OPHTHALMOLOGY
extraction was performed and the patient returned at a later date for the vitrectomy. These cases are listed as preoperatively aphakic. The mean preoperative intraocular pressure by applanation tonometry was 13 mm Hg with a range of 2 to 26 mm Hg. Preoperative posterior segment findings—The vitreous cavity contents and fundus were examined by both the slitlamp biomicroscope and the binocular indirect ophthalmoscope. These preoper ative vitreous and retinal findings were combined with the operative findings by using intraocular illumination and con tact lenses in those cases where the preop erative examination was prevented by the presence of cataracts or hemorrhages (Ta ble 5). Most of the eyes contained red or yellowish-brown hemorrhages. Posterior vitreous detachments were present in most cases except where the posterior vitreous surface was adherent to proliferative tissue. Many patients were tested for vitreous mobility after quick eye movements when examined with the slit lamp, and showed no restrictions despite many proliferations adherent to the pos terior vitreous surface. All 100 cases had some surface or eleTABLE 5 VITREOUS CAVITY FINDINGS Preoperative
Hemorrhage Absent Present No information Total
MAY, 1976
vated proliferative tissue preoperatively, and most contained proliferations that originated from both the retina and disk (Table 6). All peripheral and posterior retinal de tachments (Table 7) were caused by trac tion, and only one retinal hole was found preoperatively. There were many retinal detachments in the posterior fundus, thus demonstrating the advanced stage of the diabetic eye disease. Operative procedure and complications—Because of the poor medical status of many of the patients, 87 operations were performed with local anesthesia and general anesthesia was used for the other 13 cases. The average operating time was two hours, with a range of from one to four hours. We performed pars plana lensectomies with the vitrectomies on 67 of 83 eyes to increase our visibility of the posterior segment to permit detailed surgery, and when we thought that the lens opacity would limit the eye's future visual func tion. Lenses were also removed to provide an easier access to the filtration system from the vitreous cavity, since the lens and zonules act as a coarse barrier for the passage of cells and delay the reabsorp tion of vitreous hemorrhage. In 11 eyes we underestimated the density of the lens nucleus which complicated lens removal,
Postoperative, 5 mos or more
TABLE 6 PROLIFERATIVE NEOVASCUL AR TISSUE
7 93 0 100
66 19 15 100
Location
Preoperative
Postoperative, 5 mos or more*
28 72 0 100
68 Ö 32 100
22 78 0 100
69 0 31 100
Posterior vitreous detachment Absent Present No information Total
20 70 10 100
Not applicable
Optic nerve Absent Present No information Total
Vitreous mobility Free Restricted No information Total
44 21 35 100
Not applicable
Retina Absent Present No information Total *New proliferations.
565
PARS PLANA VITRECTOMY
VOL. 81, NO. 5 TABLE 7 RETINAL DETACHMENTS Location
Preoperative
Postoperative, 5 mos or more
Posterior fundus Absent Present No information Total
58 42 0 100
60 15 25 100
Peripheral fundus Absent Present No information Total
68 32 0 100
59 16 25 100
but this did not adversely affect the vitrectomy. In addition to the standard vitrectomy, we often used the two-instrument tech nique 1 to remove preretinal blood in 44 eyes, and to peel preretinal membranes in 27 eyes. In seven cases transvitreal dia thermy was applied to control active bleeding. The most frequent complication at sur gery was the production of dialyses and retinal holes in the areas adjacent to the entry site of the VISC (11 cases). These may have been caused by the instruments pushing on the vitreous base and pulling the retina at the ora serrata or were pro duced while we cut vitreous structures close to the retina, especially when the retina was detached. Retinal detachments developed or enlarged at surgery in five cases as a result of these retinal holes or dialyses. Additional surgical procedures were combined with vitrectomies to prevent or treat these complications: cryopexies (16 therapeutic, 14 prophylactic), injections of air or sulfur hexafluoride (SF 6 ) mixture (16 therapeutic, 13 prophylactic), and scierai buckles (six therapeutic). We often used a combination of the three. Early postoperative findings—We reevaluated the patients IV2 weeks after surgery. It was difficult to evaluate visual acuity at this time due to corneal irregu
larities and haze of the optic media, and we did not report it. However, one patient had no light perception at this examina tion and had a markedly enlarged preop erative retinal detachment. We thought it was inoperable. The most frequent early postoperative complication of vitrectomy was delayed epithelialization or recurrent epithelial sluffing of the cornea, and occurred in about one fourth of the cases (Table 8). This may have been due to the central corneal epithelium that usually was re moved at surgery to improve visibility of the posterior segment, but the ease with which the epithelium was removed indi cates a poor adhesion of the epithelium. Descemet's folds were observed in two thirds of the cases, indicating additional damage to the endothelium. Some anterior chamber flare and cells were seen in all cases. Severe flare was seen in a few eyes without any obvious explanation. Severe flare and fibrin usual ly occurred after heavy cryopexy and cleared spontaneously without the use of corticosteroids. Hyphemas occurred only in cases where there was postoperative bleeding from cut proliferative tissue. The intraocular pressures ranged from 2 to 50 mm Hg with a median of 15 mm Hg. Five eyes had pressures greater than 30 mm Hg. The usual cause of elevated pressure was thought to be residual blood TABLE 8 EARLY POSTOPERATIVE FINDINGS IN THE ANTERIOR SEGMENT No Present Absent Information Cornea Epithelial defect Descemet's folds
28 63
68 32
4 5
Anterior chamber Hyphema Severe flare (3 - 4+) Severe cells (3 - 4+)
2 11 5
95 86 91
3 3 4
566
AMERICAN JOURNAL OF OPHTHALMOLOGY
obstructing the filtration meshwork and was managed with systemic acetazolamide (Diamox). Like the anterior segment, flare and cells were usually found in the vitreous cavity. This was due to residual blood breakdown products being released from the remaining vitreous base. In 29 eyes fresh blood was seen and originated from cut proliferative tissue. In six cases rhegmatogenous retinal de tachments developed during this early postoperative period and were treated with scierai buckling procedures. Suc cessful reattachments were achieved in four cases. Vitreous haze prevented an adequate examination of the fundus in 16 cases. Late postoperative findings, five months or more—The late postoperative visual acuities of the 100 cases were com piled (Table 9). The 15 eyes with no light perception had either uncontrollable neovascular glaucoma or total retinal detach ment, and three required enucleation. Unfortunately there is nothing definite about the late postoperative visual func tion test responses (Table 2) because of the amount of incomplete information. We observed corneal abnormalities in 31 of the eyes at the late postoperative examination, but because of the frequent association with severe ocular complica tions, only a few accounted for decreased vision. Severe flare and cells were found in many eyes. Rubeosis iridis had develTABLE 9 LATE POSTOPERATIVE VISUAL ACUITY, 5 MOS OR MORE
Group 1 2 3 4 5 Total
Visual Acuity
No. of Eyes
6/5-6/12 6/15-6/60 6/90-CF HM-LP NLP
9 34 13 29 Ji5_ 100
MAY, 1976
oped in 26 eyes (Table 3). Of the eight eyes with minor preoperative rubeosis iridis, only four had identifiable rubeosis postoperatively. Since most eyes had lensectomies (Ta ble 4), there were many aphakic postoper ative eyes. The development of posterior subcapsular changes suggests that the di abetic lens after vitrectomy was suscepti ble to cataractous changes, and is an argu ment for lens removal during vitrectomy. The late postoperative intraocular pres sures had an acceptable range (6 to 30 mm Hg) in most eyes (72). Several of these eyes were being treated for elevated intra ocular pressure at the late postoperative examination with miotics, systemic acetazolamide, and some had received cyclocryotherapy. We did not investigate the number of eyes requiring medication for control of intraocular pressure. Neovascular glaucoma was the most significant postoperative complication (11 eyes) and resulted in the enucleation of three eyes. Five eyes had hypotony (0 to 5 mm Hg). Information on nine eyes could not be obtained. Vitreous cavity blood was found in 19 eyes (Table 5). No new proliferative tis sue was found postoperatively. Only shrunken remnants of proliferative tissue were seen depending on the amount of removal at surgery (Table 6). There were few (15) posterior traction retinal detach ments postoperatively (Table 7). DISCUSSION
Visual success is defined as an im provement in visual acuity of at least one visual acuity group, a visual failure is a decrease of at least one group, and no change implies that the visual acuity re mained in the same group. The visual acuity groups are broad categories since we believe vitrectomy is not justified if there is only minimal visual improve ment. The graph correlates the preoperative
PARS PLANA VITRECTOMY
VOL. 81, NO. 5
visual acuities with the late postoperative visual acuities (Figure). Those 49 cases located above and to the left of the diago nal line are visual successes; the 23 cases below and to the right of the line are visual failures; and the remaining 28 cases located on the line have unchanged visual acuity. The farther a point is locat ed from the diagonal line, the greater the visual change. Often the visual success is considerable as demonstrated by the 23 cases in preoperative Group 4 that pro gressed to Group 2 postoperatively. Four eyes maintained their preoperatively good visual acuity. This results in an overall success rate of 53%. In an attempt to find the type of pathol ogy that has the best or worst chance for visual success, the cases were divided into three categories. Cases with only vitreous hemorrhage had the highest vis ual success 2 with 34 successes (71%) and 14, no improvement or failures. In those cases where the retinopathy included a traction detachment of the posterior reti na, there was a lower chance of success with 13 successes (31%) and 29, no im provement or failures; this is expected
I
II
III
IV
V
POST-OPERATIVE VISUAL ACUITY
Figure (Mandelcorn, Blankenship, and Machemer). Correlation of postoperative visual acuity (ab scissa) with preoperative visual acuity (ordinate). The Roman numbers represent acuity groups as defined in Table 1.
567
since these cases are in a more advanced stage of the disease. The group of cases with proliferative retinopathy but no vit reous hemorrhages or traction retinal de tachments is mostly composed of eyes that had better preoperative acuities. Therefore, improved visual acuity was obtained in two cases; however, six eyes retained their original good visual acuity. In two cases vision decreased. Nineteen patients with growth-onset diabetes (20 years old or younger) had visual success (50%); 19 either had no change or a visual failure (50%); 30 pa tients with adult-onset diabetes (older than 20 years) had visual success (48%); 32 patients showed no change or had a visual failure (52%). Therefore, the visual success rate of patients with growth- and adult-onset diabetes is identical. Patients undergoing surgery after the age of 30 years have a statistically significant (P< .01) better rate of visual success—48 suc cesses (54%) and 40, no improvement or failures—than younger patients—one success (8%) and 11, no improvement or failure. An obvious reason is not appar ent. We correlated the preoperative visual function tests (Table 2) with the visual acuity results to test the reliability in predicting potential visual results. Unfor tunately, no statistically significant corre lations were found between any individu al or combination of tests and the visual results. A disappointing example is the inaccuracy of the entoptic phenomenon in predicting a good visual result. Obvi ously there are too many other factors involved in these diseased diabetic eyes that determine the final vision. Ultrasonography and bright-flash electroretinography may be more valuable prognostically. 3 We correlated late corneal problems with the lens status to identify possible factors influencing corneal clarity, but no statistically significant difference was
568
AMERICAN JOURNAL OF OPHTHALMOLOGY
found between eyes with retained lenses or aphakic eyes. These findings suggest that the lens does not protect the cornea by acting as a fluid barrier between the anterior and posterior segments, reducing potential factors such as temperature change, inadequate infusion fluids, and fluid turbulence. Corneal problems were usually associ ated with other anterior segment changes, indicated by the statistically significant (P
MAY,
1976
NUMBER 5
PARS PLANA VITRECTOMY FOR T H E MANAGEMENT O F SEVERE DIABETIC RETINOPATHY M A R K S. M A N D E L C O R N , M.D., G E O R G E B L A N K E N S H I P , AND R O B E R T M A C H E M E R , M.D. Miami,
M.D.,
Florida
Since April 1970, approximately 900 pars plana vitrectomies have been per formed here. About 50% have been for the late complications of proliferative diabet ic retinopathy. This report describes the preoperative, operative, and postopera tive anatomical findings and visual func tion of 100 consecutive cases with post operative follow-up examinations of at least five months. MATERIAL AND METHODS
Between May 1972 and November 1973, pars plana vitrectomies 1 were per formed by one of us (R.M.) on 105 con secutive eyes of patients who had devel oped late complications of diabetic reti nopathy. In this study an attempt was made to observe all patients for at least six months or more, but because of schedul ing difficulties, a few patients were exam ined five months postoperatively. When follow-up information was available after six months, this was included to provide better information about the long-term results of this operative procedure. FiftyFrom the Bascom Palmer Eye Institute, Depart ment of Ophthalmology, University of Miami School of Medicine, and the Veterans Administra tion Hospital, Miami, Florida. This study was sup ported in part by Public Health Service research grant EY-00841; by the Veterans Administration Hospital, Miami, Florida; and by the Florida Lions Eye Bank, Inc., Miami, Florida. Dr. Mandelcorn was a fellow of the Medical Research Council of Canada. Reprint requests to Robert Machemer, M.D., Bas com Palmer Eye Institute, P.O. Box 520875, Biscayne Annex, Miami, F L 33152.
seven of the eyes were examined between five and seven months after surgery, 29 were examined between eight and 12 months postoperatively, and the remain ing 14 eyes were examined more than one year after surgery. The duration of follow-up ranged from five to 30 months with a median of seven months. Five patients died before the six-month post operative examination could be per formed, leaving 100 cases for this study. An attempt was made to obtain infor mation on 220 different questions or po tential observations from each case re garding the patients' general characteris tics, visual function, and ophthalmic findings. These data were recorded at the preoperative examination, operative pro cedure, and postoperatively at IV2 weeks and at least five months later. Unfortu nately, some of the data were missing due to an inability to obtain complete followup information on cases when patients were unable to return for the planned six-month postoperative examination. Of the 100 patients, 64 returned as requested and had complete examinations, and in formation on the other 36 cases was gath ered from other ophthalmologists. Also, some of the data were occasionally miss ing due to incomplete records. Structures located posterior to opaque material in the optical media could not be examined preoperatively, but in these instances the operative findings were used. Missing or incomplete data were recorded as no in formation.
561
562
AMERICAN JOURNAL OF OPHTHALMOLOGY
The information was transferred to computer cards for analysis by two of us (M.S.M. and G.B.). Ten randomly select ed cases were independently coded to evaluate potential bias, and the interpre tation of the information was essentially identical. The data and correlations were analy zed using the chi square test for statistical significance. Probability values achieved by the chi square test on 2 X 2 tables of less than 0.01 were not considered signif icant. Only statistically significant differ ences will be mentioned. RESULTS
General characteristics—The 100 cases included 65 men and 35 women, 54 right and 46 left eyes, and the median age at surgery was 51 years with a range of 20 to 76 years. All patients were known to be diabetic and the median duration of es tablished diabetes mellitus at surgery was 20 years with a range from less than one year to 43 years. The median duration of visual symptoms relatable to diabetic retinopathy in the operated eye was three years with a range of less than one year to 18 years. Since it was thought that the vitrectomy procedure would only be jus tified if it resulted in major visual im provement, the visual acuities were grouped into broad categories: 1: reading vision, 6/5 to 6/12 (20/15 to 20/40); 2: decreased visual acuity but not legal blindness, 6/15 to 6/60 (20/50 to 20/200); 3: ambulating visual acuity, 6/90 (20/300 to counting fingers); 4: minimal visual function, hand movements to light per ception; and 5: no visual function. In addition to their diabetes, 29 pa tients had systemic hypertension, eight had cardiac disease, 14 had renal disease, and 35 had other diabetic problems (neu ropathies, decreased peripheral circula tion, and the like). Insulin was used by 80 patients, 17 were managed with oral hy poglycémie agents, two were managed by
MAY, 1976
diet alone, and one patient had had a hypophysectomy. Twenty-one eyes had been treated with photocoagulation before preoperative evaluation. Preoperative visual function—The pre operative visual acuities of most eyes were less than counting fingers (Table 1). Most eyes had dense vitreous hemorrhag es and occasional posterior traction reti nal detachments. Eyes in Groups 1 and 2 only had proliferative tissue and minor vitreous hemorrhages, and had vitrectomies to reduce vitreous traction and mini mize future hemorrhages. Subjective visual function testing uti lized the perception of the entoptic phe nomenon. 1 The perception of red color produced with a red filter, pen light, and Maddox rod were tested at a distance of 1 meter. Confrontation visual fields were used to evaluate the level of peripheral vision. Pupillary responses were exam ined to obtain a more objective measure ment of the visual function (Table 2). Traditionally the perception of both the entoptic phenomenon and color were thought to represent macular function, but the discrepancy between the positive responses of these two tests suggested that color perception reflects function of peripheral cones as well. The Maddox rod perception was frequently absent despite the presence of color perception. Most patients had retained some vision in each of the peripheral quadrants. Patients with severe diabetic retinopathy tended to TABLE 1 PREOPERATIVE VISUAL ACUITIES
Groups 1 2 3 4 5 Total
Visual Acuity 6/5-6/12 6/15-6/60 6/90-CF HM-LP NLP
No. of Eyes 1 5 24 70 0 100
PARS PLANA VITRECTOMY
VOL. 81, NO. 5
563
TABLE 2 VISUAL FUNCTION TEST RESULTS
Postoperative, 5 mos or more
Preoperative Results Absent
Present Entoptic phenomena Red color Maddox rod* Full peripheral visual field Normal pupil response
No Information
Present
Absent
No Information
20
76
4
27
40
33
76 33 74
15 49 18
9 18 8
34 34 39
25 29 29
41 37 32
20
64
16
7
52
41
* E x a m i n a t i o n a d d e d t o r o u t i n e e v a l u a t i o n after s t u d y h a d s t a r t e d .
have abnormal pupillary responses. In addition to afferent conductive defects, the response also evaluated the influence of opacities in the optic media and dam age to the iris tissue. Preoperative anterior segment findings—The anterior segments were exam ined by slit-lamp biomicroscopy. No sig nificant corneal abnormalities were ob served (Table 3). When flare and cells were found in eyes with vitreous hemorrhages, they were thought to be the breakdown products of blood, rather than actual inflammation. However, when there was severe flare, it was usually associated with extensive rubeosis iridis. These eyes were consid-
ered inoperable, as were eyes with exten sive rubeosis iridis and neovascular glau coma. Eight eyes with mild rubeosis iridis around the pupillary margins and normal intraocular pressures were in cluded. The prevalence of cataracts and aphakia is shown in Table 4. As expected in diseased diabetic eyes, most lenses had cataractous changes and many were al ready aphakic. The preoperative presence of severe nuclear sclerosis complicated the vitrectomy procedure to such a degree that in most cases, a routine ab externo cataract TABLE 4 LENS FINDINGS
TABLE 3 ANTERIOR CHAMBER FINDINGS
Preoperative Flare Absent Moderate (1 - 2+) Severe (3 - 4+) No information Total Cells Absent Moderate (1 - 2+) Severe (3 - 4+) No information Total
75 25 0 0 100 89 10 1 0 100
Postoperative, 5 mos or more 53 22 11 14 100 63 13 9 15 100
Preoperative
Postoperative, 5 mos or more
Nuclear sclerosis Absent Moderate (1 - 2 + ) Severe (3 - 4+) No information Total
29 52 2 0 83
9 3 2 2 16
Posterior subcapsular cataract Absent Moderate (1 - 2 + ) Severe (3 - 4+) No information Total
11 42 29 1 83
4 7 3 2 16
Aphakia
17
84
564
AMERICAN JOURNAL OF OPHTHALMOLOGY
extraction was performed and the patient returned at a later date for the vitrectomy. These cases are listed as preoperatively aphakic. The mean preoperative intraocular pressure by applanation tonometry was 13 mm Hg with a range of 2 to 26 mm Hg. Preoperative posterior segment findings—The vitreous cavity contents and fundus were examined by both the slitlamp biomicroscope and the binocular indirect ophthalmoscope. These preoper ative vitreous and retinal findings were combined with the operative findings by using intraocular illumination and con tact lenses in those cases where the preop erative examination was prevented by the presence of cataracts or hemorrhages (Ta ble 5). Most of the eyes contained red or yellowish-brown hemorrhages. Posterior vitreous detachments were present in most cases except where the posterior vitreous surface was adherent to proliferative tissue. Many patients were tested for vitreous mobility after quick eye movements when examined with the slit lamp, and showed no restrictions despite many proliferations adherent to the pos terior vitreous surface. All 100 cases had some surface or eleTABLE 5 VITREOUS CAVITY FINDINGS Preoperative
Hemorrhage Absent Present No information Total
MAY, 1976
vated proliferative tissue preoperatively, and most contained proliferations that originated from both the retina and disk (Table 6). All peripheral and posterior retinal de tachments (Table 7) were caused by trac tion, and only one retinal hole was found preoperatively. There were many retinal detachments in the posterior fundus, thus demonstrating the advanced stage of the diabetic eye disease. Operative procedure and complications—Because of the poor medical status of many of the patients, 87 operations were performed with local anesthesia and general anesthesia was used for the other 13 cases. The average operating time was two hours, with a range of from one to four hours. We performed pars plana lensectomies with the vitrectomies on 67 of 83 eyes to increase our visibility of the posterior segment to permit detailed surgery, and when we thought that the lens opacity would limit the eye's future visual func tion. Lenses were also removed to provide an easier access to the filtration system from the vitreous cavity, since the lens and zonules act as a coarse barrier for the passage of cells and delay the reabsorp tion of vitreous hemorrhage. In 11 eyes we underestimated the density of the lens nucleus which complicated lens removal,
Postoperative, 5 mos or more
TABLE 6 PROLIFERATIVE NEOVASCUL AR TISSUE
7 93 0 100
66 19 15 100
Location
Preoperative
Postoperative, 5 mos or more*
28 72 0 100
68 Ö 32 100
22 78 0 100
69 0 31 100
Posterior vitreous detachment Absent Present No information Total
20 70 10 100
Not applicable
Optic nerve Absent Present No information Total
Vitreous mobility Free Restricted No information Total
44 21 35 100
Not applicable
Retina Absent Present No information Total *New proliferations.
565
PARS PLANA VITRECTOMY
VOL. 81, NO. 5 TABLE 7 RETINAL DETACHMENTS Location
Preoperative
Postoperative, 5 mos or more
Posterior fundus Absent Present No information Total
58 42 0 100
60 15 25 100
Peripheral fundus Absent Present No information Total
68 32 0 100
59 16 25 100
but this did not adversely affect the vitrectomy. In addition to the standard vitrectomy, we often used the two-instrument tech nique 1 to remove preretinal blood in 44 eyes, and to peel preretinal membranes in 27 eyes. In seven cases transvitreal dia thermy was applied to control active bleeding. The most frequent complication at sur gery was the production of dialyses and retinal holes in the areas adjacent to the entry site of the VISC (11 cases). These may have been caused by the instruments pushing on the vitreous base and pulling the retina at the ora serrata or were pro duced while we cut vitreous structures close to the retina, especially when the retina was detached. Retinal detachments developed or enlarged at surgery in five cases as a result of these retinal holes or dialyses. Additional surgical procedures were combined with vitrectomies to prevent or treat these complications: cryopexies (16 therapeutic, 14 prophylactic), injections of air or sulfur hexafluoride (SF 6 ) mixture (16 therapeutic, 13 prophylactic), and scierai buckles (six therapeutic). We often used a combination of the three. Early postoperative findings—We reevaluated the patients IV2 weeks after surgery. It was difficult to evaluate visual acuity at this time due to corneal irregu
larities and haze of the optic media, and we did not report it. However, one patient had no light perception at this examina tion and had a markedly enlarged preop erative retinal detachment. We thought it was inoperable. The most frequent early postoperative complication of vitrectomy was delayed epithelialization or recurrent epithelial sluffing of the cornea, and occurred in about one fourth of the cases (Table 8). This may have been due to the central corneal epithelium that usually was re moved at surgery to improve visibility of the posterior segment, but the ease with which the epithelium was removed indi cates a poor adhesion of the epithelium. Descemet's folds were observed in two thirds of the cases, indicating additional damage to the endothelium. Some anterior chamber flare and cells were seen in all cases. Severe flare was seen in a few eyes without any obvious explanation. Severe flare and fibrin usual ly occurred after heavy cryopexy and cleared spontaneously without the use of corticosteroids. Hyphemas occurred only in cases where there was postoperative bleeding from cut proliferative tissue. The intraocular pressures ranged from 2 to 50 mm Hg with a median of 15 mm Hg. Five eyes had pressures greater than 30 mm Hg. The usual cause of elevated pressure was thought to be residual blood TABLE 8 EARLY POSTOPERATIVE FINDINGS IN THE ANTERIOR SEGMENT No Present Absent Information Cornea Epithelial defect Descemet's folds
28 63
68 32
4 5
Anterior chamber Hyphema Severe flare (3 - 4+) Severe cells (3 - 4+)
2 11 5
95 86 91
3 3 4
566
AMERICAN JOURNAL OF OPHTHALMOLOGY
obstructing the filtration meshwork and was managed with systemic acetazolamide (Diamox). Like the anterior segment, flare and cells were usually found in the vitreous cavity. This was due to residual blood breakdown products being released from the remaining vitreous base. In 29 eyes fresh blood was seen and originated from cut proliferative tissue. In six cases rhegmatogenous retinal de tachments developed during this early postoperative period and were treated with scierai buckling procedures. Suc cessful reattachments were achieved in four cases. Vitreous haze prevented an adequate examination of the fundus in 16 cases. Late postoperative findings, five months or more—The late postoperative visual acuities of the 100 cases were com piled (Table 9). The 15 eyes with no light perception had either uncontrollable neovascular glaucoma or total retinal detach ment, and three required enucleation. Unfortunately there is nothing definite about the late postoperative visual func tion test responses (Table 2) because of the amount of incomplete information. We observed corneal abnormalities in 31 of the eyes at the late postoperative examination, but because of the frequent association with severe ocular complica tions, only a few accounted for decreased vision. Severe flare and cells were found in many eyes. Rubeosis iridis had develTABLE 9 LATE POSTOPERATIVE VISUAL ACUITY, 5 MOS OR MORE
Group 1 2 3 4 5 Total
Visual Acuity
No. of Eyes
6/5-6/12 6/15-6/60 6/90-CF HM-LP NLP
9 34 13 29 Ji5_ 100
MAY, 1976
oped in 26 eyes (Table 3). Of the eight eyes with minor preoperative rubeosis iridis, only four had identifiable rubeosis postoperatively. Since most eyes had lensectomies (Ta ble 4), there were many aphakic postoper ative eyes. The development of posterior subcapsular changes suggests that the di abetic lens after vitrectomy was suscepti ble to cataractous changes, and is an argu ment for lens removal during vitrectomy. The late postoperative intraocular pres sures had an acceptable range (6 to 30 mm Hg) in most eyes (72). Several of these eyes were being treated for elevated intra ocular pressure at the late postoperative examination with miotics, systemic acetazolamide, and some had received cyclocryotherapy. We did not investigate the number of eyes requiring medication for control of intraocular pressure. Neovascular glaucoma was the most significant postoperative complication (11 eyes) and resulted in the enucleation of three eyes. Five eyes had hypotony (0 to 5 mm Hg). Information on nine eyes could not be obtained. Vitreous cavity blood was found in 19 eyes (Table 5). No new proliferative tis sue was found postoperatively. Only shrunken remnants of proliferative tissue were seen depending on the amount of removal at surgery (Table 6). There were few (15) posterior traction retinal detach ments postoperatively (Table 7). DISCUSSION
Visual success is defined as an im provement in visual acuity of at least one visual acuity group, a visual failure is a decrease of at least one group, and no change implies that the visual acuity re mained in the same group. The visual acuity groups are broad categories since we believe vitrectomy is not justified if there is only minimal visual improve ment. The graph correlates the preoperative
PARS PLANA VITRECTOMY
VOL. 81, NO. 5
visual acuities with the late postoperative visual acuities (Figure). Those 49 cases located above and to the left of the diago nal line are visual successes; the 23 cases below and to the right of the line are visual failures; and the remaining 28 cases located on the line have unchanged visual acuity. The farther a point is locat ed from the diagonal line, the greater the visual change. Often the visual success is considerable as demonstrated by the 23 cases in preoperative Group 4 that pro gressed to Group 2 postoperatively. Four eyes maintained their preoperatively good visual acuity. This results in an overall success rate of 53%. In an attempt to find the type of pathol ogy that has the best or worst chance for visual success, the cases were divided into three categories. Cases with only vitreous hemorrhage had the highest vis ual success 2 with 34 successes (71%) and 14, no improvement or failures. In those cases where the retinopathy included a traction detachment of the posterior reti na, there was a lower chance of success with 13 successes (31%) and 29, no im provement or failures; this is expected
I
II
III
IV
V
POST-OPERATIVE VISUAL ACUITY
Figure (Mandelcorn, Blankenship, and Machemer). Correlation of postoperative visual acuity (ab scissa) with preoperative visual acuity (ordinate). The Roman numbers represent acuity groups as defined in Table 1.
567
since these cases are in a more advanced stage of the disease. The group of cases with proliferative retinopathy but no vit reous hemorrhages or traction retinal de tachments is mostly composed of eyes that had better preoperative acuities. Therefore, improved visual acuity was obtained in two cases; however, six eyes retained their original good visual acuity. In two cases vision decreased. Nineteen patients with growth-onset diabetes (20 years old or younger) had visual success (50%); 19 either had no change or a visual failure (50%); 30 pa tients with adult-onset diabetes (older than 20 years) had visual success (48%); 32 patients showed no change or had a visual failure (52%). Therefore, the visual success rate of patients with growth- and adult-onset diabetes is identical. Patients undergoing surgery after the age of 30 years have a statistically significant (P< .01) better rate of visual success—48 suc cesses (54%) and 40, no improvement or failures—than younger patients—one success (8%) and 11, no improvement or failure. An obvious reason is not appar ent. We correlated the preoperative visual function tests (Table 2) with the visual acuity results to test the reliability in predicting potential visual results. Unfor tunately, no statistically significant corre lations were found between any individu al or combination of tests and the visual results. A disappointing example is the inaccuracy of the entoptic phenomenon in predicting a good visual result. Obvi ously there are too many other factors involved in these diseased diabetic eyes that determine the final vision. Ultrasonography and bright-flash electroretinography may be more valuable prognostically. 3 We correlated late corneal problems with the lens status to identify possible factors influencing corneal clarity, but no statistically significant difference was
568
AMERICAN JOURNAL OF OPHTHALMOLOGY
found between eyes with retained lenses or aphakic eyes. These findings suggest that the lens does not protect the cornea by acting as a fluid barrier between the anterior and posterior segments, reducing potential factors such as temperature change, inadequate infusion fluids, and fluid turbulence. Corneal problems were usually associ ated with other anterior segment changes, indicated by the statistically significant (P
