Graefes Arch Clin Exp Ophthalmol DOI 10.1007/s00417-015-2983-5
PEDIATRICS
Strabismus in infants following congenital cataract surgery Elif Demirkilinc Biler 1 & Duygu Inci Bozbiyik 2 & Onder Uretmen 1 & Suheyla Kose 3
Received: 14 October 2014 / Revised: 20 February 2015 / Accepted: 2 March 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Purpose This study aimed to determine the incidence and characteristics of strabismus following congenital cataract surgery in infants. Materials and methods Patients aged 2 Snellen lines. The remaining five patients had at least one amblyogenic risk factor necessitating amblyopia treatment. Secondary IOL implantation was performed in five (15.6 %) patients in group 1 and in two (4.3 %) patients in group 2. Additional surgery for aphakic glaucoma was needed in five (15.6 %) patients in group 1 and in 12 (25.5 %) patients in group 2. There was not a significant relationship between
Graefes Arch Clin Exp Ophthalmol Table 2
Patient characteristics and clinical findings of children with nystagmus
Sex • Male • Female Laterality, n • Unilateral • Bilateral Age at cataract surgery (months) Follow-up period (months) Cataract density, n • Partial • Total Presence of strabismus • Esotropia • Exotropia Development of aphakic glaucoma, n (%) Additional ocular surgery, n (%) a
Pearson chi-square test
b
Mann–Whitney U test
Nystagmus+(n=49)
Nystagmus – (n=30)
P value
30 19
18 12
0.91a
4 45 4.2±2.8 months (1–12 months) 59.6±40.4 (12–168)
10 20 4.3±2.9 months (1–11 month) 35.5±32.1 (12–175)
0.004a
10 39
9 21
0.33a
21 9 23 (46.9) 18 (36.7)
11 6 7 (23.3) 5 (16.7)
0.71a
the need for additional surgery and the incidence of strabismus (Pearson’s chi-square test, p=0.73; chi-square value=0.12) or the type of strabismus (Pearson’s chi-square test, p=0.552; chi-square value=0.36).
Discussion A high incidence of strabismus in patients with congenital cataract has been reported by many researchers; the incidence of strabismus in the general population is estimated to be 1.3– 4.5 % [12–16], whereas the prevalence of strabismus in patients with congenital cataract is 24.2–84 % [3–5, 8, 11, 17]. According to some researchers, the occurrence of strabismus increases following cataract surgery [2, 4, 5]. France [4] reported that strabismus was present preoperatively in 40 % of children at the time of diagnosis, and that it interfered with visual rehabilitation in 86 % of children that underwent surgery for congenital cataract. It has also been reported that strabismus was observed in 21 of 25 children that had congenital cataract surgery during the first 6 months of life [5]. One study reported that 16 (76.1 %) of 21 patients developed strabismus following bilateral cataract surgery performed before the age of 12 months [7]. In the present study, the incidence of strabismus was higher than in the general population. Among the 79 patients in the present study that underwent congenital cataract extraction before the age of 12 months, 47 (59.5 %) developed strabismus during the post-surgery follow-up period.
0.97b 0.001b
0.04a 0.57a
Hiles and Sheridan [3] reported that early cataract surgery and vigorous optical rehabilitation did not appear to ensure protection against strabismus. It was also reported that despite early surgical intervention and optimal postoperative management, nystagmus and strabismus were observed in a large majority of patients [11]. Magli et al. [18] reported that age at the time of cataract diagnosis and age at the time of surgery were not significantly associated with strabismus. On the other hand, Bothun et al. [19] reported that strabismus was less common in infants that underwent surgery before 49 days of age. Binocular vision first appears at the age of 3 months [21]. It is probable that infants with visually significant congenital cataracts that receive prompt treatment within these sensitive periods have a lower risk of developing amblyopia or binocular abnormalities. In the present study, all surgeries were performed before the age of 12 months, but the incidence of post-operative strabismus was still higher than in the general population, in agreement with the literature. Although the incidence of strabismus was lower in the present study’s patients that underwent surgery before the age of 3 months, it did not differ significantly according to age at the time of surgery. However, we feel that statistics failed to find the difference and that the study might be somewhat under-powered. Although not statistically significant, the lower incidence of strabismus in the present study’s patients that underwent surgery before the age of 3 months might have been associated with the fact that binocular reflexes are not yet established at age 3 months, as previously reported [20, 21]. Thus, if surgery is performed before the establishment
Graefes Arch Clin Exp Ophthalmol
of binocular reflexes, patients might be protected from strabismus, maintaining binocularity and orthophoria. Parks and Hiles [22] reported that there was a strong correlation between cataract type and the risk of strabismus; however, there was not a significant association observed between cataract density and strabismus in some other studies [12, 18]. In the present study, cataract type and density were not significantly associated with strabismus. In addition, a gender predilection for strabismus was not noted. Some researchers observed a greater predisposition to strabismus in unilateral cataract cases than in bilateral cases [4, 10, 12, 17, 18]; however, Hiles and Sheridan [3] reported that the occurrence of strabismus was equal in unilateral and bilateral cataract cases. In the present study, there was a significant difference in the occurrence of strabismus according to cataract laterality (85.7 % in unilateral cases and 53.8 % in bilateral cases), as reported in earlier studies. A decrease in or deprivation of visual stimulus in one eye in cases of unilateral cataracts during the critical period of visual maturation before surgery, and the presence of significant anisometropia or aniseikonia, which may result from aphakia correction following cataract extraction, may lead to ocular deviation [17]. Additionally, the high risk of amblyopia due to non-compliance with strict occlusion therapy in unilateral cases can play a role in the subsequent development of sensorial strabismus. France [4] observed that unilateral congenital cataract patients had esotropia or exotropia in about equal proportions; however, in bilateral cases esotropia was dominant. In other studies, esotropia was more common in congenital cataract cases [3, 8, 17, 23, 19]. On the other hand, Weisberg [12] and Park [7] reported that exotropia was more common than esotropia in their cases. In the present study, esotropia was more common in both unilateral (66.7 %) and bilateral (68.6 %) congenital cataract patients. This could be due to increasing convergence mechanisms that develop at an early age [4, 8]. In the present study, age at the time of cataract extraction did not differ significantly between the esotropic and exotropic patients, as reported by Parks [7]. Mean time between surgery and the appearance of strabismus in the present study was 13.3 months (range: 1– 60 months), which is similar to the mean 6–12 months post cataract surgery reported by Spanou [17]. Another study reported that the mean time from cataract extraction and diagnosis of strabismus was 32.5 months in patients with exotropia and 35.6 months in patients with esotropia [7]. In the present study, 70.2 % of the 47 cases of strabismus occurred during the first 12 months post cataract surgery; however, if mean survival time of 66.3 months follow-up had been available for all patients, the estimated cumulative percentage of patients with strabismus would be 66.9 % according to Kaplan–Meier survival analysis. Thus, a careful long-term follow-up is necessary for detecting strabismus post cataract surgery.
Many children treated for dense cataracts also develop nystagmus with or without strabismus [20, 24]. Nystagmus was reported to be more prevalent among children with bilateral cataracts than in children with unilateral cataracts [24–26]. In the present study, the incidence of strabismus was higher in bilateral cataract cases, and the relationship between cataract laterality and the presence of nystagmus was significant. Age at the time of surgery and duration of visual deprivation have also been proposed as risk factors for the development of nystagmus [9, 20, 25, 27]. Birch et al. [28] reported that infantile onset of cataract and visual deprivation >6 weeks were associated with a significantly higher risk of nystagmus, and that the duration of deprivation was an important factor for adverse ocular motor outcomes. Gelbart [29] reported that none of his cataract patients without nystagmus preoperatively developed it postoperatively; however, in the present study nystagmus developed in 26 cases preoperatively, and occurred in an additional 23 patients post-operatively—despite early surgery. Although the amplitude of nystagmus decreased during follow-up in some of the present study’s cases, it never resolved completely. The present study has a number of limitations. First, it was a non-randomized retrospective study, and although none of children had strabismus pre-operatively, it is possible that we might have missed cases with small angles of strabismus preoperatively. Moreover, without binocular tests there is a possibility that cases with small angles of strabismus postoperatively were also missed, which might have led to misdiagnosis of the time of onset, and possibly even misassignment to a group. Secondly, stereoacuity was not assessed in a majority of the patients. Very few patients were able to cooperate sufficiently for binocularity testing at the final follow-up visit; therefore, findings related to binocularity were not obtained. On the other hand, all the patients underwent complete strabismological evaluation at each follow-up visit by two different ophthalmologists, and via this method underestimation of the number of strabismic patients was minimized. Lastly, we did not group the patients according to their characterictics further and did not perform subgroup analysis of cataract type, so it is possible that this study was underpowered to find differences and interactions across the subgroups. In conclusion, management of both monocular and binocular congenital cataracts remains a clinical challenge. The present findings confirm the high frequency of strabismus in congenital cataract patients, even if they undergo surgery at a very young age. The presence of strabismus in these patients represents a significant problem, because it constitutes an additional amblyopia-producing factor that negatively affects postoperative treatment [30]. As strabismus and nystagmus occur more frequently in children undergoing cataract surgery than in the general population, careful long-term follow-up is necessary in these children for monitoring of the development of strabismus.
Graefes Arch Clin Exp Ophthalmol Conflict of interest No conflicting relationship exists for any author and there is no financial support or interest related to the material in the manuscript.
References 1. 2. 3. 4. 5.
6.
7. 8. 9.
10.
11. 12.
13.
14.
Lambert SR, Drack AV (1996) Infantile cataracts. Surv Ophthalmol 40:427–458 Fallaha N, Lambert SR (2001) Pediatric cataracts. Ophthalmol Clin North Am 14:479–492 Hiles DA, Sheridan SJ (1977) Strabismus associated with infantile cataracts. Int Ophthalmol Clin 17:193–202 France TD, Frank JW (1984) The association of strabismus and aphakia in children. J Pediatr Ophthalmol Strabismus 21:223–226 Lambert SR, Lynn M, Drews-Botsch C et al (2001) A comparison of grating visual acuity, strabismus, and reoperation outcomes among children with aphakia and pseudophakia after unilateral cataract surgery during the first six months of life. J AAPOS 5:70–75 Parks MM, Johnson DA, Reed GW D1993] Long-term visual results and complications in children with aphakia. A function of cataract type. Ophthalmology 100:826–840, discussion 840–41 Park SH, Na JH, Shin SY (2010) Strabismus following bilateral cataract surgery in childhood. Jpn J Ophthalmol 54:272–277 Merino P, Gómez-de-Liaño P, Gil MR et al (2007) Strabismus and congenital cataracts. Arch Soc Esp Oftalmol 82:623–628 Birch EE, Cheng C, Stager DR Jr, Weakley DR Jr, Stager DR (2009) The critical period for surgical treatment of dense congenital bilateral cataracts. J AAPOS 13:67–71 Lesueur LC, Arne JL, Chapotot EC, Thouvenin D, Malecaze F (1998) Visual outcome after paediatric cataract surgery: is age a major factor? Br J Ophthalmol 82:1022–1025 Abadi RV, Forster JE, Lloyd IC (2006) Ocular motor outcomes after bilateral and unilateral infantile cataracts. Vision Res 46:940–952 Weisberg OL, Sprunger DT, Plager DA, Neely DE, Sondhi N (2005) Strabismus in pediatric pseudophakia. Ophthalmology 112(9):1625–1628 Greenberg AE, Mohney BG, Diehl NN, Burke JP (2007) Incidence and types of childhood esotropia: a population-based study. Ophthalmology 114(1):170–174 Govindan M, Mohney BG, Diehl NN, Burke JP (2005) Incidence and types of childhood exotropia: a population-based study. Ophthalmology 112(1):104–108
15.
Kornder LD, Nursey JN, Pratt-Johnson JA, Beattie A (1974) Detection of manifest strabismus in young children. 2. A retrospective study. Am J Ophthalmol 77:211–214 16. Friedman Z, Neumann E, Hyams SW, Peleg B (1980) Ophthalmic screening of 38,000 children, age 1 to 2½years, in child welfare clinics. J Pediatr Ophthalmol Strabismus 17:261–267 17. Spanou N, Alexopoulos L, Manta G, Tsamadou D, Drakos H, Paikos P (2011) Strabismus in pediatric lens disorders. J Pediatr Ophthalmol Strabismus 48:163–166 18. Magli A, Iovine A, Bruzzese D, Giani U, Fimiani F (2008) Strabismus in developmental cataract. Eur J Ophthalmol 18:540– 543 19. Bothun ED, Cleveland J, Lynn MJ, Christiansen SP, Vanderveen DK, Neely DE, Kruger SJ, Lambert SR (2013) Infant Aphakic Treatment Study. One-year strabismus outcomes in the Infant Aphakia Treatment Study. Ophthalmology 120(6):1227–1231 20. Watts P, Abdolell M, Levin AV (2003) Complications in infants undergoing surgery for congenital cataract in the first 12 weeks of life: is early surgery better? J AAPOS 7(2):81–85 21. Chandna A (1991) Natural history of development of visual acuity in infants. Eye 5:20–26 22. Parks MM, Hiles DA (1967) Management of infantile cataracts. Am J Ophthalmol 63:10–19 23. Lundvall A, Kugelberg U (2002) Outcome after treatment of congenital bilateral cataract. Acta Ophthalmol Scand 80(6):593–597 24. Hussin HM, Markham R (2009) Long-term visual function outcomes of congenital cataract surgery with intraocular lens implantation in children under 5 years of age. Eur J Ophthalmol 19(5): 754–761 25. Lambert SR, Drack AV (1996) Infantile cataracts. Surv Ophthalmol 40(6):427–458 26. Wright KW, Christensen LE, Noguchi BA (1992) Results of late surgery for presumed congenital cataracts. Am J Ophthalmol 114(4):409–415 27. Ye H, Deng D, Qian Y, Lin Z, Chen W (2007) Long-term visual outcome of dense bilateral congenital cataract. Chin Med J 120(17): 1494–1497 28. Birch EE, Wang J, Felius J, Stager DR, Hertle RW (2012) Fixation control and eye alignment in children treated for dense congenital or developmental cataracts. J AAPOS 16:156–160 29. Gelbart SS, Hoyt CS, Jasterbski G, Marg E (1982) Long term visual results in bilateral congenital cataracts. Am J Ophthalmol 93:615– 621 30. Hosal BM, Biglan AW, Elhan AH (2000) High levels of binocular function are achievable after removal of monocular cataracts in children before 8 years of age. Ophthalmology 107(9):1647–1655
PEDIATRICS
Strabismus in infants following congenital cataract surgery Elif Demirkilinc Biler 1 & Duygu Inci Bozbiyik 2 & Onder Uretmen 1 & Suheyla Kose 3
Received: 14 October 2014 / Revised: 20 February 2015 / Accepted: 2 March 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Purpose This study aimed to determine the incidence and characteristics of strabismus following congenital cataract surgery in infants. Materials and methods Patients aged 2 Snellen lines. The remaining five patients had at least one amblyogenic risk factor necessitating amblyopia treatment. Secondary IOL implantation was performed in five (15.6 %) patients in group 1 and in two (4.3 %) patients in group 2. Additional surgery for aphakic glaucoma was needed in five (15.6 %) patients in group 1 and in 12 (25.5 %) patients in group 2. There was not a significant relationship between
Graefes Arch Clin Exp Ophthalmol Table 2
Patient characteristics and clinical findings of children with nystagmus
Sex • Male • Female Laterality, n • Unilateral • Bilateral Age at cataract surgery (months) Follow-up period (months) Cataract density, n • Partial • Total Presence of strabismus • Esotropia • Exotropia Development of aphakic glaucoma, n (%) Additional ocular surgery, n (%) a
Pearson chi-square test
b
Mann–Whitney U test
Nystagmus+(n=49)
Nystagmus – (n=30)
P value
30 19
18 12
0.91a
4 45 4.2±2.8 months (1–12 months) 59.6±40.4 (12–168)
10 20 4.3±2.9 months (1–11 month) 35.5±32.1 (12–175)
0.004a
10 39
9 21
0.33a
21 9 23 (46.9) 18 (36.7)
11 6 7 (23.3) 5 (16.7)
0.71a
the need for additional surgery and the incidence of strabismus (Pearson’s chi-square test, p=0.73; chi-square value=0.12) or the type of strabismus (Pearson’s chi-square test, p=0.552; chi-square value=0.36).
Discussion A high incidence of strabismus in patients with congenital cataract has been reported by many researchers; the incidence of strabismus in the general population is estimated to be 1.3– 4.5 % [12–16], whereas the prevalence of strabismus in patients with congenital cataract is 24.2–84 % [3–5, 8, 11, 17]. According to some researchers, the occurrence of strabismus increases following cataract surgery [2, 4, 5]. France [4] reported that strabismus was present preoperatively in 40 % of children at the time of diagnosis, and that it interfered with visual rehabilitation in 86 % of children that underwent surgery for congenital cataract. It has also been reported that strabismus was observed in 21 of 25 children that had congenital cataract surgery during the first 6 months of life [5]. One study reported that 16 (76.1 %) of 21 patients developed strabismus following bilateral cataract surgery performed before the age of 12 months [7]. In the present study, the incidence of strabismus was higher than in the general population. Among the 79 patients in the present study that underwent congenital cataract extraction before the age of 12 months, 47 (59.5 %) developed strabismus during the post-surgery follow-up period.
0.97b 0.001b
0.04a 0.57a
Hiles and Sheridan [3] reported that early cataract surgery and vigorous optical rehabilitation did not appear to ensure protection against strabismus. It was also reported that despite early surgical intervention and optimal postoperative management, nystagmus and strabismus were observed in a large majority of patients [11]. Magli et al. [18] reported that age at the time of cataract diagnosis and age at the time of surgery were not significantly associated with strabismus. On the other hand, Bothun et al. [19] reported that strabismus was less common in infants that underwent surgery before 49 days of age. Binocular vision first appears at the age of 3 months [21]. It is probable that infants with visually significant congenital cataracts that receive prompt treatment within these sensitive periods have a lower risk of developing amblyopia or binocular abnormalities. In the present study, all surgeries were performed before the age of 12 months, but the incidence of post-operative strabismus was still higher than in the general population, in agreement with the literature. Although the incidence of strabismus was lower in the present study’s patients that underwent surgery before the age of 3 months, it did not differ significantly according to age at the time of surgery. However, we feel that statistics failed to find the difference and that the study might be somewhat under-powered. Although not statistically significant, the lower incidence of strabismus in the present study’s patients that underwent surgery before the age of 3 months might have been associated with the fact that binocular reflexes are not yet established at age 3 months, as previously reported [20, 21]. Thus, if surgery is performed before the establishment
Graefes Arch Clin Exp Ophthalmol
of binocular reflexes, patients might be protected from strabismus, maintaining binocularity and orthophoria. Parks and Hiles [22] reported that there was a strong correlation between cataract type and the risk of strabismus; however, there was not a significant association observed between cataract density and strabismus in some other studies [12, 18]. In the present study, cataract type and density were not significantly associated with strabismus. In addition, a gender predilection for strabismus was not noted. Some researchers observed a greater predisposition to strabismus in unilateral cataract cases than in bilateral cases [4, 10, 12, 17, 18]; however, Hiles and Sheridan [3] reported that the occurrence of strabismus was equal in unilateral and bilateral cataract cases. In the present study, there was a significant difference in the occurrence of strabismus according to cataract laterality (85.7 % in unilateral cases and 53.8 % in bilateral cases), as reported in earlier studies. A decrease in or deprivation of visual stimulus in one eye in cases of unilateral cataracts during the critical period of visual maturation before surgery, and the presence of significant anisometropia or aniseikonia, which may result from aphakia correction following cataract extraction, may lead to ocular deviation [17]. Additionally, the high risk of amblyopia due to non-compliance with strict occlusion therapy in unilateral cases can play a role in the subsequent development of sensorial strabismus. France [4] observed that unilateral congenital cataract patients had esotropia or exotropia in about equal proportions; however, in bilateral cases esotropia was dominant. In other studies, esotropia was more common in congenital cataract cases [3, 8, 17, 23, 19]. On the other hand, Weisberg [12] and Park [7] reported that exotropia was more common than esotropia in their cases. In the present study, esotropia was more common in both unilateral (66.7 %) and bilateral (68.6 %) congenital cataract patients. This could be due to increasing convergence mechanisms that develop at an early age [4, 8]. In the present study, age at the time of cataract extraction did not differ significantly between the esotropic and exotropic patients, as reported by Parks [7]. Mean time between surgery and the appearance of strabismus in the present study was 13.3 months (range: 1– 60 months), which is similar to the mean 6–12 months post cataract surgery reported by Spanou [17]. Another study reported that the mean time from cataract extraction and diagnosis of strabismus was 32.5 months in patients with exotropia and 35.6 months in patients with esotropia [7]. In the present study, 70.2 % of the 47 cases of strabismus occurred during the first 12 months post cataract surgery; however, if mean survival time of 66.3 months follow-up had been available for all patients, the estimated cumulative percentage of patients with strabismus would be 66.9 % according to Kaplan–Meier survival analysis. Thus, a careful long-term follow-up is necessary for detecting strabismus post cataract surgery.
Many children treated for dense cataracts also develop nystagmus with or without strabismus [20, 24]. Nystagmus was reported to be more prevalent among children with bilateral cataracts than in children with unilateral cataracts [24–26]. In the present study, the incidence of strabismus was higher in bilateral cataract cases, and the relationship between cataract laterality and the presence of nystagmus was significant. Age at the time of surgery and duration of visual deprivation have also been proposed as risk factors for the development of nystagmus [9, 20, 25, 27]. Birch et al. [28] reported that infantile onset of cataract and visual deprivation >6 weeks were associated with a significantly higher risk of nystagmus, and that the duration of deprivation was an important factor for adverse ocular motor outcomes. Gelbart [29] reported that none of his cataract patients without nystagmus preoperatively developed it postoperatively; however, in the present study nystagmus developed in 26 cases preoperatively, and occurred in an additional 23 patients post-operatively—despite early surgery. Although the amplitude of nystagmus decreased during follow-up in some of the present study’s cases, it never resolved completely. The present study has a number of limitations. First, it was a non-randomized retrospective study, and although none of children had strabismus pre-operatively, it is possible that we might have missed cases with small angles of strabismus preoperatively. Moreover, without binocular tests there is a possibility that cases with small angles of strabismus postoperatively were also missed, which might have led to misdiagnosis of the time of onset, and possibly even misassignment to a group. Secondly, stereoacuity was not assessed in a majority of the patients. Very few patients were able to cooperate sufficiently for binocularity testing at the final follow-up visit; therefore, findings related to binocularity were not obtained. On the other hand, all the patients underwent complete strabismological evaluation at each follow-up visit by two different ophthalmologists, and via this method underestimation of the number of strabismic patients was minimized. Lastly, we did not group the patients according to their characterictics further and did not perform subgroup analysis of cataract type, so it is possible that this study was underpowered to find differences and interactions across the subgroups. In conclusion, management of both monocular and binocular congenital cataracts remains a clinical challenge. The present findings confirm the high frequency of strabismus in congenital cataract patients, even if they undergo surgery at a very young age. The presence of strabismus in these patients represents a significant problem, because it constitutes an additional amblyopia-producing factor that negatively affects postoperative treatment [30]. As strabismus and nystagmus occur more frequently in children undergoing cataract surgery than in the general population, careful long-term follow-up is necessary in these children for monitoring of the development of strabismus.
Graefes Arch Clin Exp Ophthalmol Conflict of interest No conflicting relationship exists for any author and there is no financial support or interest related to the material in the manuscript.
References 1. 2. 3. 4. 5.
6.
7. 8. 9.
10.
11. 12.
13.
14.
Lambert SR, Drack AV (1996) Infantile cataracts. Surv Ophthalmol 40:427–458 Fallaha N, Lambert SR (2001) Pediatric cataracts. Ophthalmol Clin North Am 14:479–492 Hiles DA, Sheridan SJ (1977) Strabismus associated with infantile cataracts. Int Ophthalmol Clin 17:193–202 France TD, Frank JW (1984) The association of strabismus and aphakia in children. J Pediatr Ophthalmol Strabismus 21:223–226 Lambert SR, Lynn M, Drews-Botsch C et al (2001) A comparison of grating visual acuity, strabismus, and reoperation outcomes among children with aphakia and pseudophakia after unilateral cataract surgery during the first six months of life. J AAPOS 5:70–75 Parks MM, Johnson DA, Reed GW D1993] Long-term visual results and complications in children with aphakia. A function of cataract type. Ophthalmology 100:826–840, discussion 840–41 Park SH, Na JH, Shin SY (2010) Strabismus following bilateral cataract surgery in childhood. Jpn J Ophthalmol 54:272–277 Merino P, Gómez-de-Liaño P, Gil MR et al (2007) Strabismus and congenital cataracts. Arch Soc Esp Oftalmol 82:623–628 Birch EE, Cheng C, Stager DR Jr, Weakley DR Jr, Stager DR (2009) The critical period for surgical treatment of dense congenital bilateral cataracts. J AAPOS 13:67–71 Lesueur LC, Arne JL, Chapotot EC, Thouvenin D, Malecaze F (1998) Visual outcome after paediatric cataract surgery: is age a major factor? Br J Ophthalmol 82:1022–1025 Abadi RV, Forster JE, Lloyd IC (2006) Ocular motor outcomes after bilateral and unilateral infantile cataracts. Vision Res 46:940–952 Weisberg OL, Sprunger DT, Plager DA, Neely DE, Sondhi N (2005) Strabismus in pediatric pseudophakia. Ophthalmology 112(9):1625–1628 Greenberg AE, Mohney BG, Diehl NN, Burke JP (2007) Incidence and types of childhood esotropia: a population-based study. Ophthalmology 114(1):170–174 Govindan M, Mohney BG, Diehl NN, Burke JP (2005) Incidence and types of childhood exotropia: a population-based study. Ophthalmology 112(1):104–108
15.
Kornder LD, Nursey JN, Pratt-Johnson JA, Beattie A (1974) Detection of manifest strabismus in young children. 2. A retrospective study. Am J Ophthalmol 77:211–214 16. Friedman Z, Neumann E, Hyams SW, Peleg B (1980) Ophthalmic screening of 38,000 children, age 1 to 2½years, in child welfare clinics. J Pediatr Ophthalmol Strabismus 17:261–267 17. Spanou N, Alexopoulos L, Manta G, Tsamadou D, Drakos H, Paikos P (2011) Strabismus in pediatric lens disorders. J Pediatr Ophthalmol Strabismus 48:163–166 18. Magli A, Iovine A, Bruzzese D, Giani U, Fimiani F (2008) Strabismus in developmental cataract. Eur J Ophthalmol 18:540– 543 19. Bothun ED, Cleveland J, Lynn MJ, Christiansen SP, Vanderveen DK, Neely DE, Kruger SJ, Lambert SR (2013) Infant Aphakic Treatment Study. One-year strabismus outcomes in the Infant Aphakia Treatment Study. Ophthalmology 120(6):1227–1231 20. Watts P, Abdolell M, Levin AV (2003) Complications in infants undergoing surgery for congenital cataract in the first 12 weeks of life: is early surgery better? J AAPOS 7(2):81–85 21. Chandna A (1991) Natural history of development of visual acuity in infants. Eye 5:20–26 22. Parks MM, Hiles DA (1967) Management of infantile cataracts. Am J Ophthalmol 63:10–19 23. Lundvall A, Kugelberg U (2002) Outcome after treatment of congenital bilateral cataract. Acta Ophthalmol Scand 80(6):593–597 24. Hussin HM, Markham R (2009) Long-term visual function outcomes of congenital cataract surgery with intraocular lens implantation in children under 5 years of age. Eur J Ophthalmol 19(5): 754–761 25. Lambert SR, Drack AV (1996) Infantile cataracts. Surv Ophthalmol 40(6):427–458 26. Wright KW, Christensen LE, Noguchi BA (1992) Results of late surgery for presumed congenital cataracts. Am J Ophthalmol 114(4):409–415 27. Ye H, Deng D, Qian Y, Lin Z, Chen W (2007) Long-term visual outcome of dense bilateral congenital cataract. Chin Med J 120(17): 1494–1497 28. Birch EE, Wang J, Felius J, Stager DR, Hertle RW (2012) Fixation control and eye alignment in children treated for dense congenital or developmental cataracts. J AAPOS 16:156–160 29. Gelbart SS, Hoyt CS, Jasterbski G, Marg E (1982) Long term visual results in bilateral congenital cataracts. Am J Ophthalmol 93:615– 621 30. Hosal BM, Biglan AW, Elhan AH (2000) High levels of binocular function are achievable after removal of monocular cataracts in children before 8 years of age. Ophthalmology 107(9):1647–1655
