Long-Term Visual Acuity and Its Predictors after Surgery for Congenital Cataract: Findings of the British Congenital Cataract Study

Abstract

purpose. To report long-term postoperative visual acuity in a nationally representative group of children with congenital/infantile cataract and to investigate the factors associated with poor vision.

methods. All children aged less than 16 years in the United Kingdom who had newly diagnosed congenital/infantile cataract in a 12-month period during 1995–1996 (the British Congenital/infantile Cataract Study) were traced through their managing ophthalmologists. Outcome data were collected at least 6 years after diagnosis, by using specifically designed questionnaires. Ordinal regression analysis identified factors associated with postoperative acuity.

results. Of 153 children who had surgery, complete data were available in 122 (85%). Median age at follow-up was 7 and 6.91 years, respectively, for bilateral and unilateral disease. Median age at surgery was 4.57 months in bilateral and 2.99 months in unilateral cases, with 40% and 45%, respectively, of children operated on by 3 months. Median (range) postoperative acuity was 6/18 (6/5, no perception of light) in bilateral and 6/60 (6/5, no perception of light) in unilateral disease. Poor compliance with occlusion was the factor most strongly associated with poorer acuity in both unilateral and bilateral disease: the odds of worse vision in unilateral cataract were 7.92 times greater with <50% versus 100% compliance (95% CI 1.68–37.26). In bilateral disease, odds of worse vision were reduced with each month of decreasing age at surgery (0.98, 95% CI 0.94–0.99), but increased by the presence of additional medical conditions (3.53, 95% CI 1.08–11.44) and the presence of postoperative ocular complications (2.94, 95% CI 1.38–6.51).

conclusions. These findings support a secular improvement in postoperative acuity in bilateral, and to a lesser extent, unilateral disease. Nevertheless early detection of congenital cataract through effective newborn screening and improving concordance with occlusion both remain priorities. Further improvements in outcomes in unilateral disease are necessary before parents can be advised universally that treatment will achieve a functionally useful “spare” eye.

Congenital cataract is a priority of Vision 2020: the Right to Sight, the global initiative to reduce the world’s burden of avoidable blindness, ¹ because it is an important treatable cause of visual handicap in childhood throughout the world. The management of this disorder has long challenged clinicians, but the past few decades have seen the most significant changes in approaches to management, informed by basic scientific and clinical research. ^{2 3 4 5 6} Visual loss is mainly attributable to amblyopia, most important, to stimulus–form deprivation amblyopia with the additional factor of ocular rivalry in unilateral disease. Thus, enhanced understanding of critical periods of visual development has led to surgical intervention for dense cataract being deemed necessary within the first 3 months of life, possibly as early as the first 6 weeks in unilateral disease. ^{3 4 5} The need to ensure early detection, to allow prompt treatment, has resulted in implementation of various strategies—in particular, whole population screening examinations of newborns in many countries. Concurrently, there have been improvements in methods for the assessment of visual acuity in preverbal children. Together, these advances have led to a shift in emphasis to the management of amblyopia through calibrated occlusion regimens. ^{2 7 8} Equally important, there have also been major advances in microsurgical techniques and instrumentation matched by developments in contact lens and intraocular lens (IOL) technology. ^{2 6 9} Improvements in all these aspects have together underpinned the better visual outcomes more recently reported in young children who undergo cataract extraction. ^{6 7 8 9}  

However, to date, outcomes of congenital and infantile cataract and their associations have generally been reported only in case series, which are intrinsically prone to selection bias and confounding, and they have also often been based on relatively short-term follow-up. Few questions about the treatment of congenital and infantile cataract have been addressed through randomized controlled trials. ^{10 11 12} Clinical factors postulated to be important to visual outcome in children are age at diagnosis and surgery, type of refractive correction, type of cataract surgery, compliance with occlusion regimen, etiology of cataract, presence of nonophthalmic disorders, development of capsular opacity or secondary membrane, and serious ocular postoperative complications. ^{2 6 7 8 9 13 14 15 16 17} Despite recent, and continuing, changes in the management of congenital/infantile cataract, there has been very limited large-scale, population-based research on outcomes. We report long-term postoperative visual acuity in a unique nationally representative group of children with congenital/infantile cataract, together with the factors associated with poor vision. 

Methods

All children with newly diagnosed congenital/infantile cataract in the United Kingdom in a 12-month period in 1995 and 1996 (previously identified for the British Congenital/Infantile Cataract study ^{18 19 20 21 22} ) who underwent surgery were eligible for the present study. We have reported elsewhere ^{18 19 20 21 22} the methodological details regarding original recruitment. To summarize, ophthalmologists and pediatricians actively reported through two independent national surveillance schemes all children under the age of 16 years with newly diagnosed, visually significant congenital or infantile cataract, irrespective of treatment undertaken. Children with diagnosis after the age of 1 year were eligible only if, on review, the cataract was due to a congenital cause or had specific ophthalmic features indicative of early onset, such as cataract morphology or associated congenital ocular anomaly. Children in whom cataract was acquired—for example, as a result of trauma, uveitis, irradiation, or drugs—were not eligible. For the present study, all children originally in the cohort were traced through their managing ophthalmologist. Detailed clinical information about management and outcomes was collected by using specifically designed questionnaires between September 2002 and April 2003 inclusive. For data validation, patients managed at ophthalmic units contributing more than four children were independently examined by the principal investigator to elicit the outcome data and, in addition, the case notes were reviewed to assess the accuracy of previously reported data. 

Statistical Analysis

From the extant literature described earlier ^{2 13 14 15 16 17} the factors considered, a priori, to be of interest in relation to visual outcome were age at presentation, time since presentation, age at cataract surgery, time since cataract surgery, compliance with occlusion regimen, type of cataract surgery, type of refractive correction, primary IOL implantation, etiology of cataract, presence of nonophthalmic disorders, development of capsular opacity or secondary membrane and serious postoperative complications. 

First, any statistical relationships between these potential predictors were investigated. Then, ordinal logistic regression analyses were undertaken to investigate the associations between these factors and postoperative visual acuity. Initially, the effect of each factor was investigated (univariate analysis). Then, the independent effects of each significant factor, taking into account all other significant factors (i.e., joint effects) were investigated (multivariate analyses). We analyzed unilateral and bilateral cases separately because of the inherent differences in terms of factors related to amblyopia and visual outcomes. Furthermore, for children with bilateral cataract, the correlation of acuity outcomes from the same individual was accounted for by the use of two-level hierarchical models (level 1 is the eye and level 2 is the child). ²³ Analysis was undertaken on computer using commercial software (Stata, 2003; Stata Corp., College Station, TX). Results are presented with 95% confidence intervals (CIs). 

To ensure reliable and stable acuity measures, as well as the capture of major postoperative complications, we excluded 12 children for whom follow-up data were available only until the age of 5 years. Snellen acuity measures were used in the analysis, as most (82%) children had vision recorded in this format by the use of standard crowded Snellen charts, with the remainder (71 children, 18%) tested with standard crowded logMAR (logarithm of the minimum angle of resolution) charts. Furthermore, Snellen measurements are made on an ordinal scale that readily incorporates the more extreme categorical outcomes (hand movements, perception of light, nonperception of light) to be included in the analysis. Thus, acuity measures recorded as logMAR (71 children, 18%) were transposed to Snellen notation. Clinicians were asked to report compliance with occlusion and their method of assessment (parental report, diaries or log books, or other means). They also reported the percentage of intended occlusion achieved, as a categorical variable (<50%, 50%, 75%, or 100%), which was used in the analysis of the effect of compliance. 

The study adhered to the tenets of the Declaration of Helsinki, was approved by the Great Ormond Street Hospital/Institute of Child Health local research ethics committee, and complied with extant research governance requirements. 

Results

One hundred fifty-three children had surgery for congenital cataract and were at least 5 years old at follow-up, as summarized in Figure 1 . One hundred thirteen children (48%, 54 girls) had bilateral cataract and a median age at follow-up of 7 years, whereas 40 (58%, 23 girls) with unilateral disease had a median age of 6.91 years at follow-up. Denominators for different data items vary and are reported separately in the Figures 1 and 2and Tables 1 2 3 4 5 6 7 , as appropriate. In 16% of cases, examined independently by the first author, review of the case notes revealed no significant errors or inconsistencies requiring amendment of the dataset before analysis. 

Median postoperative visual acuity (6/18) in the eyes of children with bilateral cataracts was better than the median acuity (6/60) of the eyes with cataract of children with unilateral disease (Fig. 1) . The distributions of postoperative visual acuity, shown in Figure 2 , also differed, with the distribution for the bilateral group being skewed toward the better-acuity end of the spectrum and in the converse direction in the unilateral group. 

The median age at surgery of the children with bilateral cataract was 4.57 months (range, 5 days at 12.12 years), with 40% operated on by 3 months. The median age at surgery of the children with unilateral cataract was 2.99 months (15 days to 5.66 years), with 45% operated on by 3 months. The types of cataract surgery undertaken are shown in Table 1 . Lensectomy and vitrectomy was marginally more common than lens aspiration in both bilateral and unilateral cases. Ninety-nine children with bilateral cataract who had both extracted had the same procedure in each eye (Figure 1) . 

In the children with bilateral cataract, 73 (34%) of 212 eyes had primary IOLs, and in the children with unilateral cataract, 14 (35%) of 40 had primary IOLs. Median age (range) at surgery for primary IOL implantation in children with bilateral cataracts, by eye, was 4.39 years (range, 0.08–12.12), and the median age of implantation in children with unilateral cataract was younger (2.84 years; range, 0.25–4.78). Only 12 eyes underwent implantation at ages younger than 2 years. 

Forty-eight eyes of 38 children had serious postoperative ocular complications, as shown in Table 2 , which included glaucoma, retinal detachment, and endophthalmitis. In addition, 9 of 40 eyes of children with unilateral cataract and 34 of 212 eyes of children with bilateral cataract showed postoperative capsular/secondary membranes. 

The classification of the underlying or associated factors for congenital cataract at the last follow-up visit is shown in Table 3 . 

In unilateral cases, there was a strong statistical correlation between age at presentation and age at surgery (P ≤ 0.005; Spearman’s correlation coefficient, 0.89), as well as an association between age at presentation and compliance (P = 0.05; Kruskal-Wallis score, 10.04). In bilateral cases, there were associations between age at cataract surgery and compliance (P = 0.04; Kruskal-Wallis score, 8.39), as well as serious postoperative complications (P ≤ 0.005; Mann-Whitney score, 3.04). The implications of these statistical associations for the analyses are discussed later. 

Table 4presents the findings of the preliminary univariate analysis and Table 5the findings of the subsequent multivariate analyses of the associations between the factors of interest and visual acuity in bilateral cataract. These are depicted as the odds that the acuity in an eye will be in a worse category, in the presence of the factor of interest (categoric predictors) or with a unit change in the factor (numeric predictors) and after taking account of the within-person correlation between eyes. Several specific variables, when assessed individually—that is, before taking into account any other factors (univariate analysis)—were associated with visual outcome (Table 4) . These included age at presentation and surgery, having an isolated cataract, type of cataract surgery, having primary IOL implantation, compliance with occlusion, presence of other medical conditions, and occurrence of postoperative capsular opacification. 

Table 5shows that age at cataract surgery, compliance with the occlusion regimen, the presence of other medical conditions, and the presence of serious postoperative complications were all independently associated with acuity outcome. 

The odds of being in a worse visual acuity category were reduced with each month of decreasing age at surgery. By contrast, the odds of being in a worse visual acuity category were greater for those children with additional medical condition(s) compared with those without and also were greater for those with a postoperative complication than those without. In addition, the odds of achieving a worse VA with 50% compliance were much greater than with 100% compliance. That the finding of compliance of less than 50% was not similarly significantly associated (at the 5% level) may reflect the smaller sample size of this subgroup, together with the statistical correlation between age at cataract surgery and compliance described earlier. 

Tables 6 and 7present the findings of the univariate and multivariate analyses, respectively, of the associations between the factors of interest and visual acuity in unilateral cataract. Several specific variables, when assessed individually—that is, before taking into account any other factors (univariate analysis)—were associated with visual outcome (Table 6) . These included age at presentation, primary IOL implantation, compliance with occlusion, and occurrence of postoperative capsular opacification. Notably, as shown in Table 7 , after adjustment for differences in compliance, no other factors were significantly associated with outcome, perhaps because of the associations described earlier between age at presentation and both compliance and age at surgery, as well as between age at surgery and serious postoperative complications. Thus, for completeness, as age at presentation is considered a key determinant of visual outcomes (and was significantly associated in the univariate analysis), it was retained in the final model, for which the findings are presented in Table 7 . 

Discussion

We report postoperative visual acuity in a nationally representative and contemporary group of children with congenital cataract, together with the factors associated with poor postoperative vision. These findings serve as a starting point for clinicians and parents of affected children alike in making decisions about treatment which is long-term, complex, and intensive. Thus, they also provide useful baseline data on distribution of visual function that will be useful for assessing whether emerging therapeutic approaches lead to improved visual outcomes. 

Potential limitations of the study include the nonstandardization of surgical techniques and occlusion protocols, together with the use of outcomes data, which although collected systematically, were reported by a large number of ophthalmologists. However, as children were managed by individuals with special expertise in congenital cataract, and data were validated independently in a 16% subsample, the findings can be viewed as reporting reliable functional outcomes. Furthermore, the nature and size of the population studied offers unique advantages in relation to minimizing selection bias and increasing precision. 

Direct comparisons with previous studies, comprising case series rather than whole populations, is not straightforward because of inherent methodological differences. Nonetheless, in broad terms, acuity outcomes in the present study are toward the better end of the ranges that have been reported previously for bilateral cataract, ^{24 25 26 27} and are also generally better than those historically described for unilateral disease. ^{14 25 28} These findings, in particular in relation to unilateral cataract, are consistent with a recent secular trend of improving visual outcomes. ²⁹ This trend is likely to be accounted for by a combination of improved management of amblyopia (through earlier detection and surgery, increased emphasis on occlusion and better methods for correction of postoperative refractive error) occurring in parallel with advances in surgical techniques, instrumentation, and materials. 

It is noteworthy that half of all children with bilateral disease in the present study achieved a level of acuity (6/18) that is conventionally considered the threshold for mainstream schooling, using printed media and with only minimal extra help. ²⁵ This finding should help inform parents of children with congenital cataract who are embarking on treatment and has implications for educational resource allocation. By contrast, only one in five children with unilateral cataract achieved this level of vision in the treated eye. Thus, despite appropriate surgery and amblyopia treatment, these children may fail to realize the useful “spare” eye that clinicians and parents often consider to be main goal of treating unilateral disease. ³⁰ We therefore suggest continued circumspection in advising families considering treatment for their children with unilateral cataract, where that is the major consideration. 

It is notable that compliance with occlusion (i.e., concordance with prescribed treatment) was the factor most strongly associated with visual outcome in bilateral as well as unilateral disease, although the strength of this association was greater for the latter. This reflects the important impact of competitive inhibition in addition to that of stimulus/form deprivation per se in unilateral (or sometimes in very asymmetrical bilateral) disease. ^{7 9 16} We recognize that because compliance was not objectively measured, but rather was assessed through direct parental questioning and validation of clinical notes, recall bias and other potential sources of error may have resulted in overestimation of the amount of occlusion achieved. ^{31 32} More reliable measurement of compliance would be achieved by using an occlusion dose monitor (a modified occlusion patch connected to a data logger), ^{31 32} which would be recommended in future prospective investigations. Nevertheless, the fact that the association between compliance and acuity could be elicited and quantified, even with the less refined measure of compliance obtained by routine assessment in usual clinical practice, attests to its significance. ^{2 24 33} There is an extensive body of literature regarding dose and duration of occlusion in the management of congenital cataract. ^{7 13 14 15 16 17} However, the barriers to effective initiation and maintenance of occlusion remain significant. They are also relatively underresearched, although a clinically important association between poor compliance and social deprivation has been reported. ³⁴ Increased input by orthoptists into supporting occlusion and actively enabling parents embarking on treatment to speak with others who have successfully managed it have both been recommended for children with other forms of amblyopia. ³⁵ These may also be appropriate for children with congenital cataract. Providing written information for parents regarding the critical period, the importance of occlusion, and the potential negative effects of not treating amblyopia have also been shown to be beneficial in improving compliance. ³⁶ There remains a need for investigations that combine objective assessment of occlusion achieved (rather than that prescribed), together with quantitative and qualitative approaches to capturing child and parental experiences of occlusion over time—for example, through questionnaire instruments such as the Amblyopia Treatment Index ³⁷ and/or the Protective Motivation Theory Questionnaire. ³⁵  

Our study quantifies the established association of better outcome with earlier surgery in children with bilateral cataract. Although this association was not replicated in the statistical model for unilateral disease, this may be accounted for by the correlation between age at surgery and age at presentation and, in turn, the latter variable’s further association with compliance. Previous reports in the literature have recommended early surgery, albeit at different points, less than 8 weeks. ^{25 26 38} Early detection is crucial for timely surgical intervention. ²⁵ In the United Kingdom, screening for ophthalmic disorders is undertaken within a broader context of a national program of child health surveillance. The recommendations of the National Screening Committee (NSC) of the United Kingdom about screening for visual deficits and ophthalmic disorders ³⁹ are consistent with recent guidelines elsewhere. ⁴⁰ It is advised that all newborns be assessed for media opacities by examination of the pupillary red reflex, inspection of the eyes, and inquiries about visual behavior. A repeat examination is advised at 6 to 10 weeks. However, the need for improvements in the training of screening pediatricians is recognized. ^{19 41} Routine monitoring and audit of the screening program at a national level could help to ensure that standards are maintained. Routine examination has also been recommended in children with a known family history of hereditary cataracts, to ensure prompt detection. This approach also requires professional awareness of the need to respond actively to parental concerns. ³⁹  

Although surgery for visually significant cataract must be within the critical period, to prevent amblyopia, complications also have been shown to increase with earlier surgery. ⁴² In this study, there was a significant association between age at surgery and serious postoperative complications, echoing the findings of other studies. ^{25 26 27} These postoperative complications were associated with a poorer visual outcome. There is a need therefore to balance the timing of surgery to prevent amblyopia with the best time to minimize postoperative complications. The point of equilibrium is unknown. A prospective trial in which children could be randomized to surgery at different ages within the critical period in which treatment is likely to be most effective (by convention currently considered to be up to 8 weeks of age in dense unilateral and approximately 12 weeks in bilateral disease), could address the key question of the optimum timing. 

That the presence of other nonophthalmic disorders was associated with poorer visual acuity in bilateral disease in the present study is consistent with prior reports ^{24 26} and is likely to reflect additional causes of poor vision, such as learning impairment or cerebral visual impairment and difficulties of acuity assessment in some children. 

As primary IOL implantation was undertaken in only 12 eyes of children ≤2 years old in our study, reflecting prevailing management practices in 1995–1996, there is limited statistical power for investigations of the outcomes of this approach, which is increasingly advocated by some for infants with cataract. It remains to be shown through population-based studies and randomized clinical trials that IOL implantation offers additional visual benefits without increased risk of complication. 

We suggest that our findings provide evidence of recent improvement over time in the visual prognosis in bilateral, and to a lesser degree, unilateral cataract, in children in industrialized countries. This improvement has been achieved through earlier detection and referral of affected children for appropriate surgical, medical, and optical treatment. Nevertheless, there is room for further improvement, which will necessitate continued implementation of existing effective screening and treatment strategies together with research-based innovation in these areas, to achieve the international goal of reducing the burden of avoidable childhood visual impairment due to congenital cataract. 

Appendix 1

Members of the British Congenital Cataract Interest Group

M. Abdel-Khalek, W. Aclimandos, G. Adams, S. Aftab, L. Allen, L. A. Amanat, S. Armstrong, A. Assaf, N. J. Astbury, D. Bannerjee, A. Barr, L. Beck, A. Beckingsale, G. Bedford, L. Benjamin, B. Billington, T. Blamires, P. Bloom, D. Boase, J. Bolger, M. Boodhoo, R. Bowell, J. Bradbury, J. Brazier, A. Bron, D. Brosnahan, R. Brown, R. Brown, S. Bryan, J. Bryars, R. Buckley, P. Burgess, J. Burke, L. Butler, D. Calver, A. Casswell, A. Chandna, W. Church, J. Clarke, M. Clarke, M. Coffey, M. Cole, R. Condon, P. Corridan, M. Dang, R. Darvell, B . Das, P. D. Davies, S. Daya, R. De Cock, C. Dees, C. Dodd, R. Doran, G. Dutton, J. Duvall-Young, C. Edelsten, R. Edwards, H. El-Kasaby, J. Elston, B. Enoch, A. Evans, N. Evans, G. Fahy, A. Fielder, F. F. Fisher, D. Flaye, B. Fleck, W. Frank, A. Gaskell, N. George, M. Gibbens, B. Greaves, P. Gregory, R. Gregson, S. J. Hardman, S. Haworth, M. H. Heravi, P. Hodgkins, R. Holden, R. Humphry, C. Hutchinson, J. Innes, I. Jalili, C. Jenkins, E. Johnson, N. Kaushik, N. Kayali, S. Keightley, P. Khaw, R. Kinnear, S. Kotta, Y. Kumar, T. Lavy, D. Laws, J. Leitch, C. Liu, C. Lloyd, C. MacEwen, A. Macfarlane, G. Mackintosh, A. Mandal, R. Markham, J. McConnell, G. McGinnity, B. McLeod, A. Misra, K. Mohamad, A. Moore, B. Moriarty, G. Morrice, R. Morris, C. Munton, M. Neugebauer, W. Newman, K. Nischal, J. Nolan, G. O’Connor, M. O’Keefe, R. Ohri, S. Perry, R. Phillips, S. Pieris, B. Power, N. Price, A. Quinn, I. Qureshi, A. Rahman, A. Rennie, A. Ridgway, M. Roper- Hall, E. Rosen, I. I. Russell-Eggitt, A. Shun Shin, A. D. Simcock, I . Simmons, M. Tappin, R. Taylor, D. Taylor, V. Thaller, D. Thoung, W. Tormey, S. Tuft, M. Tutton, J. Twomey, S. Verghese, S. Vickers, A. Vijaykumar, A. Vivian, C. Williams, H. Willshaw, G. Woodruff, G. Wright, B. Young, A. Zaidi. 

⁴  The ^appendix provides a full list of the study group members.

 Supported by a grant from the Guide Dogs for the Blind Association. Research at the Institute of Child Health and Great Ormond Street Hospital for Children National Health Service (NHS) Trust benefits from research and development funding received from the NHS Executive.

 Submitted for publication August 30, 2005; revised December 6, 2005, and March 27, May 11, and May 18, 2006; accepted August 15, 2006.

 Disclosure: M. Chak, None; A. Wade, None; J.S. Rahi, None

 The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked “advertisement” in accordance with 18 U.S.C. §1734 solely to indicate this fact.

 

Figure 1.

 

Flow chart of study subjects with descriptive statistics.

Figure 2.

 

Distribution of visual acuities (Snellen equivalent) for surgically treated eyes of children with cataract, by laterality. HM, hand movements; NPL, no perception of light.

Table 1.

 

Cataract Surgery Procedures

Type of Cataract Surgery	Laterality of Cataract*			Total
		Bilateral (n = 209)	Unilateral (n = 40)
Lensectomy/vitrectomy
Primary IOL	7	2	9
No IOL	92	17	109
Lens aspiration
Primary IOL	43	8	51
No IOL	23	4	27
Lens aspiration and vitrectomy
Primary IOL	23	4	27
No IOL	21	5	26

*  Data available for 209/212 (99%) eyes of bilateral cases and 40/40 eyes of unilateral cases.

Table 2.

 

Serious Postoperative Ocular Complications

Complication	Laterality of Cataract
		Bilateral (n = 29; 39 eyes)	Unilateral (n = 9; 9 eyes)
Glaucoma (postoperative open angle and closed angle)	17 (15%) children	6 (13%) children
	26 (11.7%) eyes	6 (13%) eyes
Retinal detachment	2 (1.7%) children	1 (2.2%) child
	3 (1.3%) eyes	1 (2.2%) eye
Endophthalmitis	1 (0.8%) child
	1 (0.4%) eye
Wound leak	1 (0.8%) child	1 (2.2%) child
	1 (0.4%) eye	1 (2.2%) eye
Vitreous hemorrhage requiring vitrectomy	7 (8.3%) children
	7 (4.3%) eyes
Collapsed anterior chamber requiring revision	1 (0.8%) child
	1 (0.4%) eye

Table 3.

 

Classification of Underlying or Associated Causes of Congenital Cataracts (by Child)

Category	Laterality			Total
		Bilateral (n = 113)	Unilateral (n = 40)
Isolated	68 (60%)	15 (37%)	83 (53%)
With associated ocular disorders	17 (15%)	21 (52%)	38 (24%)
With associated ocular and systemic disorders	5 (4%)	3 (8%)	8 (7%)
With associated systemic disorders	23 (21%)	1 (3%)	24 (16%)

Table 4.

 

Univariate Ordinal Logistic Regression Analysis of Factors Associated with Visual Acuity in Bilateral Cataract

Variable	Relative Odds of Having Worse Acuity (95% CI*)	P *
Time since presentation (mo)	1.015 (0.983–1.047)	0.34
Decreasing age at presentation (mo)	0.097 (0.956–0.980)	<0.001
Time since surgery (mo)	1.010 (0.997–1.025)	0.14
Decreasing age at cataract surgery (mo)	0.978 (0.968–0.987)	<0.001
Correction
Glasses (baseline)	—
Contact lens	1.57 (0.57–3.41)	0.36
Contact lens and glasses, †	7.61 (1.27–51.71)	0.05
Type of cataract surgery
Aspiration alone (baseline), ‡	—
Lens aspiration and vitrectomy, ‡	2.53 (1.21–6.52)	0.02
Lensectomy-vitrectomy, ‡	2.24 (1.67–7.12)	<0.005
Primary IOL implantation	2.29 (2.22–9.91)	0.03
Compliance with occlusion
100% compliance (baseline)	—
75% compliance	1.43 (0.47–3.54)	0.53
50% compliance	0.55 (0.08–2.51)	0.56
<50% compliance	3.16 (1.21–10.87)	0.04
Etiology
Systemic (baseline), §	—
Isolated, §	0.18 (0.05–0.47)	<0.005
Ocular, §	0.41 (0.16–1.78)	0.71
Ocular systemic, §	0.31 (0.02–4.92)	0.57
Presence of other medical conditions	0.47 (0.01–0.93)	0.03
Presence of serious postoperative complication	0.46 (0.21–0.97)	0.05
Posterior capsular opacity/secondary membrane	1.28 (1.21–1.97)	<0.005

  n = 204 eyes; 109 children.

*  CI and P adjusted for correlation between outcomes for both eyes of the same child.

†  Correction (CL and glasses) indicates use of both modalities at any time during the study period. CL and glasses vs. CL relative odds = 0.21, CI = 0.41–1.71, P = 0.34.

‡  Lens aspiration and vitrectomy vs. lensectomy-vitrectomy: relative odds = 1.40, CI = 0.01–3.74, P = 0.52.

§  Ocular vs. isolated: relative odds = 0.43, CI = 0.08–0.95, P = 0.02. Ocular vs. Ocular-systemic: relative odds = 0.76 CI = 0.05–16.21, P = 0.89. Ocular systemic vs. isolated: relative odds = 0.56, CI = 0.05–6.42, P = 0.64.

Table 5.

 

Multivariate (Joint-Effects) Analysis of Factors Associated with Worse Acuity in Bilateral Cataract

Variable	Relative Odds of Having Worse Acuity (95% CI*)	P *
Decreasing age at cataract surgery (mo)	0.980 (0.944–0.999)	0.03
Compliance with occlusion
100% (baseline)	—
75% compliance	0.56 (0.22–1.42)	0.22
50% compliance	5.64 (3.01–8.81)	0.02
<50% compliance	1.17 (0.26–5.18)	0.84
Presence of other medical conditions	3.53 (1.08–11.44)	0.04
Presence of postoperative complications	2.94 (1.38–6.51)	0.04

  n = 204 eyes; 109 children.

*  CI and P adjusted for correlation between outcomes for both eyes of the same child.

Table 6.

 

Univariate Ordinal Logistic Regression Analysis of Factors Associated with Visual Acuity Unilateral Cataract

Variable	Relative Odds of Having a Worse Acuity (CI)	P
Time since presentation (mo)	1.03 (0.97–1.08)	0.31
Decreasing age at presentation (mo)	0.97 (0.94–0.99)	0.05
Time since surgery (mo)	0.98 (0.93–1.02)	0.41
Decreasing age at cataract surgery (mo)	0.98 (0.96–1.02)	0.32
Correction
Glasses (baseline)	—
Contact lens	1.72 (0.37–9.21)	0.49
Type of cataract surgery
Lens aspiration alone (baseline)*	—
Lens aspiration and vitrectomy*	1.96 (0.91–10)	0.42
Lensectomy-vitrectomy*	1.95 (0.52–1.38)	0.99
Primary IOL implantation	4.90 (1.35–17.81)	0.02
Compliance
100% compliance with occlusion regimen (baseline)†	—
75% compliance	0.54 (0.06–4.48)	0.58
50% compliance	11.59 (1.49–89.12)	0.02
<50% compliance	50.40 (5.31–473.42)	<0.005
Etiology
OcularSystemic (baseline), ‡	—
Isolated, ‡	0.30 (0.02–4.01)	0.36
Ocular, ‡	0.70 (0.03–4.57)	0.42
Presence of other medical conditions	0.85 (0.26–2.80)	0.79
Severe cataract at presentation	1.34 (0.17–10.59)	0.78
Presence of postoperative complication	0.26 (0.05–1.28)	0.10
Posterior capsular opacity/secondary membrane	4.06 (1.07–15.42)	0.04

  n = 40 children.

*  Type of cataract surgery: lens aspiration and vitrectomy vs. lensectomy-vitrectomy; relative odds = 1.00, CI = 0.21–4.66, P = 1.00.

‡  Etiology: ocular vs. isolated, relative odds = 0.85, CI = 0.26–2.80, P = 0.79.

Table 7.

 

Multivariate (Joint-Effects) Analysis of Factors Associated with Worse Acuity in Unilateral Cataract

Variable	Relative Odds of Having a Given Acuity or Worse (95% CI)	P
Decreasing age at presentation (mo)	0.997 (0.964–1.031)	0.84
Compliance with occlusion
100% (baseline)	—
75% compliance	0.99 (0.11–7.81)	0.95
50% compliance	7.92 (1.68–37.26)	0.01
<50% compliance	9.78 (1.34–71.00)	0.02

  n = 40.

The authors thank all the children and families who participated in the project, as well the members of the British Congenital Cataract Interest Group (BCCIG) for their contributions and David Taylor for his comments on an early draft of the manuscript.