Critical Period Of Visual Development Research Articles

Using the visual cliff and pole descent assays to detect binocular disruption in mice.

Amblyopia, a neurodevelopmental visual disorder characterized by impaired stereoacuity, is commonly modeled in animals using monocular deprivation (MD) during a critical period of visual development. Despite extensive research at the synaptic, cellular and circuit levels of analysis, reliable behavioral assays to study stereoscopic deficits in mice are limited. This study aimed to characterize the Visual Cliff Assay (VCA) and the Pole Descent Cliff Task (PDCT) in mice, and to evaluate their utility in detecting binocular dysfunction. Using these assays, we investigated the impact of clinically relevant manipulations of binocular vision, including monocular occlusion, pupillary dilation, and amblyopia induced by long-term MD. Our findings reveal that optimal performance in both the VCA and PDCT are dependent on balanced binocular input. However, deficits after MD in the VCA exhibited relatively small effect sizes (7-14%), requiring large sample sizes for statistical comparisons. In contrast, the PDCT demonstrated larger effect sizes (43-61%), allowing for reliable detection of binocular dysfunction with a smaller sample size. Both assays were validated using multiple monocular manipulations relevant to clinical paradigms, with the PDCT emerging as the preferred assay for detecting deficits in stereoscopic depth perception in mice. These findings provide a robust framework for using the VCA and PDCT in mechanistic and therapeutic studies in mice, offering insights into the neural mechanisms of binocular vision and potential interventions for amblyopia.

Ten-year outcomes of congenital cataract surgery performed within the first six months of life.

To investigate the long-term outcomes of congenital cataract surgery performed within the first 6 months of life. 11 ophthalmic surgical sites in Japan. Retrospective chart review. Medical charts were retrospectively reviewed for 216 eyes of 121 patients. The age at surgery was 2.9 ± 1.7 months, with follow-up duration 13.0 ± 2.3 years. The cohort consisted of 83 cases with bilateral aphakia, 12 with bilateral pseudophakia, 20 with unilateral aphakia, and 6 with unilateral pseudophakia. Surgical intervention within the critical period of visual system development (10 weeks for bilateral and 6 weeks for unilateral cases) led to significantly better final visual acuity than surgery conducted after this time frame. The incidence of secondary glaucoma was similar between groups while the occurrence of visual axis opacification was more frequent with earlier surgery. A forward stepwise multiple regression analysis revealed that the final visual acuity was significantly associated with laterality of cataract (better outcomes in bilateral cases), phakic status (with pseudophakia outperforming aphakia), presence of systemic and ocular comorbidities, and development of secondary glaucoma. Secondary glaucoma was significantly more prevalent in aphakic eyes than pseudophakic eyes. In patients with genuine congenital cataract, surgery within the critical period of visual development results in better final visual acuity, albeit with an increased risk of visual axis opacification. The use of IOL with sophisticated surgical techniques shows promise even in congenital cataract surgery.

Myopic progression in school-aged children with moderate intermittent exotropia.

It is still controversial whether intermittent exotropia (IXT) affects myopic progression during the critical period of visual development. This study retrospectively analyzed the long-term myopic changes and the impact of IXT surgery on myopic progression in school-aged children with moderate IXT. The medical records of 65 children from 5 to 13 years old with or without IXT between 2015 and 2021 were retrospectively reviewed. Patients whose spherical equivalent refraction (SER) were less than -3.00 diopter (D) were included and divided into three groups: IXT surgery group (Group A), which comprised 22 IXT patients who received IXT surgery, IXT observation group (Group B), which comprises 19 IXT patients who only received long-term observational follow-up; and normal control group (Group C), which comprised 24 normal controls without IXT. The main outcome measurement was the rate of myopic progression, which was defined as the mean myopic shift in SER per year. The 3- and 5-years long-term follow-up rates of myopic progression were -0.47 ± 0.28 D per year and -0.48 ± 0.23 D per year respectively in Group B, and those were significantly slower than that in Group C (-0.73 ± 0.32 D per year and -0.76 ± 0.19 D per year respectively). However, there was no significant difference in the rate of myopic progression between Group A and B or between Group A and C. Moderate IXT may have lower rate of myopic progression in school-aged children. Whether IXT surgery influence the rate of myopic progression still needs further study.

Cortical Reorganization After Optical Alignment in Strabismic Patients Outside of Critical Period.

To measure visual crowding, an essential bottleneck on object recognition and reliable psychophysical index of cortex organization, in older children and adults with horizontal concomitant strabismus before and after strabismus surgery. Using real-time eye tracking to ensure gaze-contingent display, we examined the peripheral visual crowding effects in older children and adults with horizontal concomitant strabismus but without amblyopia before and after strabismus surgery. Patients were asked to discriminate the orientation of the central tumbling E target letter with flankers arranged along the radial or tangential axis in the nasal or temporal hemifield at different eccentricities (5° or 10°). The critical spacing value, which is the minimum space between the target and the flankers required for correct discrimination, was obtained for comparisons before and after strabismus surgery. Twelve individuals with exotropia (6 males, 21.75 ± 7.29 years, mean ± SD) and 15 individuals with esotropia (6 males, 24.13 ± 5.96 years) participated in this study. We found that strabismic individuals showed significantly larger critical spacing with nasotemporal asymmetry along the radial axis that related to the strabismus pattern, with exotropes exhibiting stronger temporal field crowding and esotropes exhibiting stronger nasal field crowding before surgical alignment. After surgery, the critical spacing was reduced and rebalanced between the nasal and temporal hemifields. Furthermore, the postoperative recovery of stereopsis was associated with the extent of nasotemporal balance of critical spacing. We find that optical realignment (i.e., strabismus surgery) can normalize the enlarged visual crowding effects, a reliable psychophysical index of cortical organization, in the peripheral visual field of older children and adults with strabismus and rebalance the nasotemporal asymmetry of crowding, promoting the recovery of postoperative stereopsis. Our results indicated a potential of experience-dependent cortical organization after axial alignment even for individuals who are out of the critical period of visual development, illuminating the capacity and limitations of optics on sensory plasticity and emphasizing the importance of ocular correction for clinical practice.

Awareness and Attitude Towards Digital Screen-Based Binocular Vision Therapy Amongst Eye Care Practitioners of Karnataka

Amblyopia interferes in the critical period of visual development among children. Due to the limitations of conventional management of patching therapy, in the recent decade digital screen based binocular vision therapy was introduced. We aimed to study the awareness and attitude of eye care practitioners towards digital screen based binocular vision therapy in management of amblyopia. The study has been conducted by constructing and validating a questionnaire. The questionnaire was validated through a pilot study. Around 104 eye care practitioners responded to the survey, showing 96% of the eye care practitioners’ awareness towards refractive correction as the first line of management for amblyopia. A high number of respondents (83%) were aware of prescribing computer-based video games for amblyopia therapy in the clinical practice. 'The visual function improvement is very much feasible with digital screen based binocular vision therapy’ was the opinion of 55% (n=52) of eye care practitioners.

Efficacy of vision therapy for unilateral refractive amblyopia in children aged 7\u201310\u2009years

BackgroundThere is a critical period for visual development, conventionally considered to be the first 6 years of life. Children aged 7 years and older are significantly less responsive to amblyopia treatment. This study investigated the efficacy of binocular vision therapy in amblyopic children aged 7–10 years.MethodsThis retrospective study enrolled 36 children with unilateral amblyopia who were divided into a case group (receiving vision therapy, optical correction, and part-time patching of the weaker eye) and a control group (receiving optical correction and part-time patching of the weaker eye). Visual acuity (VA) was measured at baseline, at the 3-month, 6-month, and 9-month visits, and 3 months after cessation of treatment.ResultsThere were 19 subjects in the case group and 17 subjects in the control group. Mean VA in the case group improved from 0.39 ± 0.24 logMAR at baseline to 0.10 ± 0.23 logMAR at the endpoint of treatment (p < 0.001, paired t-test). Mean VA in the control group improved from 0.64 ± 0.30 logMAR at baseline to 0.52 ± 0.27 logMAR at the endpoint of treatment (p = 0.015, paired t-test). The improvement was significantly greater in the case group than in the control group (p = 0.006, two-samples independent t-test). All subjects underwent follow-up examinations within 6 to 12 months. There was no regression of VA in the case group 3 months after cessation of vision therapy. The patients in the case group who received visual therapy were with better VA improvement then patients with only optic correction and patching.ConclusionsVision therapy combined with conventional treatment (optical correction and part-time patching) is more effective than conventional treatment alone in children aged 7–10 years with unilateral refractive amblyopia. The treatment results not only in greater vision gain, but also in shorter duration of treatment.

Binocular therapy as primary intervention in adults with anisometropic amblyopia.

PURPOSE:Refractive correction and patching is the timetested mainstay of treatment for anisometropic amblyopia within the critical period of visual development. Binocular therapies using dichoptic training which overcome suppression by balancing the contrast between two eyes has been increasingly gaining ground. We evaluated the efficacy of dichoptic training in the adult population with anisometropic amblyopia. This study aims to evaluate the effectiveness of dichopticbased active vision therapy, using “VisuoPrime” software as primary intervention, in adults with anisometropic amblyopes.MATERIALS AND METHODS:A prospective interventional study in adults (18–40 years) with anisometropic amblyopia was conducted from August 2019 to March 2020. METHODS: Twentynine subjects with anisometropic amblyopia played binocular games through “VisuoPrime” software 30 min daily for 6 weeks. Bestcorrected visual acuity (BCVA) and binocularity was assessed at 1 and 3 months. Student's paired ttest, Wilcoxon signedrank sum test and MannWhitney tests were used. Statistical package of SPSS version 20.0 was used for analysis, considering P < 0.05 as statistically significant.RESULTS:BCVA of the amblyopic eye improved from 0.60 ± 0.40 logMAR to 0.45 ± 0.29 logMAR and 0.38 ± 0.23 logMAR at 1 and 3 months, respectively (P = 0.0001). Near acuity improved from 0.21 ± 0.14 to 0.14 ± 0.08 logMAR and 0.1 ± 0.04 logMAR at 1 and 3 months respectively (P < 0.0001). Improvement in stereopsis was observed in 24% of subjects which maintained at 3 month followup.CONCLUSION:Dichopticbased active vision therapy using “VisuoPrime” software was effective as a primary modality in adults with anisometropic amblyopia.

Amblyopia and Routine Eye Exam in Children: Parent's Perspective.

Amblyopia is a reduced best-corrected visual acuity of one or both eyes that cannot be attributed to a structural abnormality; it is a functional reduction in the vision of an eye caused by disuse during a critical period of visual development. It is considered the leading cause of visual defects in children. With early diagnosis and treatment, children with amblyopia can significantly improve their vision. However, if it is neglected and not treated during childhood, unfortunately, it permanently decreases vision. Therefore, prevention, detection, and treatment largely depend on parents. This article explores parents’ perspectives on amblyopia and routine examination of their children’s eyes. A cross-sectional study used an electronic questionnaire consisting of five main sections to assess the level of awareness of amblyopia among parents. As a result, a total of 325 participants were included in our analysis. 209 (64.3%) were mothers, and 116 (35/7%) were fathers. The age groups were 35–50 years of age (61.5%), 20–34 years (23.4%), and older than 50 years (15%). Participants with a history of amblyopia numbered 23 (7.1%), and 39 had an amblyopic child (12%). A good awareness level of amblyopia among parents was found in only 10 (3%) participants, a fair awareness level in 202 (62%), and 113 (35%) participants were classified as having a poor awareness level of amblyopia. Only 13.8% of the parents took their children for yearly routine eye exams, while the majority (72%) took their children only if they had a complaint, and 14.2% took them for eye checkups only before school entry. In conclusion, parents’ awareness of amblyopia in Tabuk City, KSA, was low. In addition, a limited proportion of parents reported consistently taking their children for routine eye exams. Therefore, raising awareness should be considered in public education regarding the disease.

Synaptosomal Actin Dynamics in the Developmental Visual Cortex Regulate Behavioral Visual Acuity in Rats.

PurposeSynaptosomal actin dynamics are essential for synaptic structural stability. Whether actin dynamics are involved in structural and functional synaptic plasticity within the primary visual cortex (V1) or behavioral visual acuity in rats has still not been thoroughly investigated.MethodsSynaptosome preparation and western blot analysis were used to analyze synaptosomal actin dynamics. Transmission electron microscopy was used to detect synaptic density and mitochondrial area alterations. A visual water maze task was applied to assess behavioral visual acuity. Microinjection of the actin polymerization inhibitor or stabilizer detected the effect of actin dynamics on visual function.ResultsActin dynamics, the mitochondrial area, and synaptic density within the area of V1 are increased during the critical period for the development of binocularity. Microinjection of the actin polymerization inhibitor cytochalasin D into the V1 decreased the mitochondrial area, synaptic density, and behavioral visual acuity. Long-term monocular deprivation reduced actin dynamics, the mitochondrial area, and synaptic density within the V1 contralateral to the deprived eye compared with those ipsilateral to the deprived eye and impaired visual acuity in the amblyopic eye. In addition, the mitochondrial area, synaptic density, and behavioral visual acuity were improved by stabilization of actin polymerization by jasplakinolide microinjection.ConclusionsDuring the critical period of visual development of binocularity, synaptosomal actin dynamics regulate synaptic structure and function and play roles in behavioral visual acuity in rats.

Ocular and adnexal anomalies in craniofacial microsomia: Type and prevalence in a multicentre cohort study

The aim of this multicentre retrospective cohort study was to describe and categorize the types of ocular and adnexal anomalies seen in patients with craniofacial microsomia (CFM) and to determine their prevalence. In addition, the relationship between the OMENS-Plus and Pruzansky–Kaban classification for each patient and the presence of ocular anomalies was investigated. A total of 881 patients with CFM from four different craniofacial centres were included. Data on ocular anomalies were gathered from the patient charts. Ocular anomalies were present in 33.9% of patients. Four subgroups of ocular and adnexal anomalies were identified. Type I ocular anomalies were present in 22.2%, type II in 19.0%, type III in 18.4%, and type IV in 14.5%. Several potentially preventable and treatable ocular anomalies were identified. Higher OMENS-Plus classification orbit and soft tissue scores and Pruzansky–Kaban classification mandible scores were associated with an increased risk of ocular anomalies. Based on these results and the clinical implications ocular anomalies may have, we underline the importance of targeted ophthalmological screening in CFM. Healthcare professionals should be aware of the possibility of ocular anomalies in these patients, especially during the critical period for visual development.

Protein expression of MEF2C during the critical period for visual development in vervet monkeys

During the early development of the visual cortex, there is a critical period when neuronal connections are highly sensitive to changes in visual input. Deprivation of visual stimuli during the critical period elicits robust anatomical and physiological rearrangements in the monkey visual cortex and serves as an excellent model for activity-dependent neuroplasticity. DNA microarray experiments were previously performed in our lab to analyze gene expression patterns in area V1 of vervet monkeys subjected to monocular deprivation (MD). An interesting candidate identified in its screen was myocyte enhancer-binding factor 2C (MEF2C), a transcription factor linked to neuronal survival. Consistent with the microarray data, we show that there is a qualitative increase in MEF2C protein expression in area V1 of infant as compared to adult vervet monkeys. Our results suggest that the regulation of neuronal survival is one of the molecular mechanisms underlying the critical period for visual cortical neuroplasticity.

Effects of Monocular Perceptual Learning on Binocular Visual Processing in Adolescent and Adult Amblyopia.

SummaryRe-establishing normal binocular visual processing is the key to amblyopia recovery beyond the critical period of visual development. Here, by combining perceptual learning, behavioral testing, and steady-state visually evoked potentials (SSVEPs), we examined how monocular perceptual learning in the amblyopic eye could change binocular visual processing in the adolescent and adult amblyopic visual system. We found that training reduced the interocular difference between amblyopic and fellow eyes and increased the amplitude of a binocular SSVEP component, with a significant negative correlation between the two measures. Our results demonstrate that training in the amblyopic eye primarily improves binocular rather than monocular visual processing in the amblyopic visual system, suggesting that behavioral training could potentially address key neural deficits in adolescent and adult amblyopia.

Cortical Alterations by the Abnormal Visual Experience beyond the Critical Period: A Resting-state fMRI Study on Constant Exotropia

ABSTRACTPurpose: The pathological mechanisms of constant exotropia (XT) are still not understood. This study aimed to critically investigate whether patients with XT express neuronal activity changes after the critical period of visual development and further explore how these alterations are associated with behavioral performance.Materials and methods: Fourteen patients with XT and 16 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (fMRI). The regional homogeneity (ReHo) method was used to evaluate spontaneous brain activities. The association between significantly altered mean ReHo values and behavioral performance was assessed using Pearson’s correlation analysis.Results: Compared with HCs, the right secondary visual cortex (V2) in patients with XT exhibited increased ReHo values, whereas the left Brodmann area 47 (BA47) demonstrated decreased spontaneous ReHo values. In patients with XT, the correlation between the left BA47’s mean ReHo value and duration of strabismus was positively significant.Conclusions: These findings indicate that patients with XT have severe neural dysfunction in the right V2 and left BA47, and pathological severity in the left BA47 is likely influenced by duration of ongoing strabismus. Therefore, these results may provide clinically important information toward understanding the underlying pathological mechanisms of XT and thus can be fundamental in future XT research.

Atropine Penalization Versus Occlusion Therapies for Unilateral Amblyopia after the Critical Period of Visual Development: A Systematic Review.

IntroductionAmblyopia therapy appears to be most effective in children under the age of 7 years, but results from randomized control trials (RCTs) have shown that occlusion therapy and/or atropine penalization therapy may improve visual acuity in an older age group. Which of these two therapies is the most effective with fewer adverse effects in an older age group has not yet been agreed upon.MethodsWe systematically searched the literature for RCTs that compared atropine penalization therapy and occlusion therapy in terms of their visual acuity outcomes and adverse events and performed a meta-analysis on the visual acuity data obtained. The adverse effects reported and their implications for clinical practice are discussed.ResultsTwo RCTs were identified, with the authors of both concluding that there was no detectable difference between the two therapies for the age groups they studied. The mean difference between atropine penalization and occlusion therapies was calculated to be − 0.01 logMAR (95% confidence interval − 0.07 to 0.03 logMAR) in favor of occlusion therapy, and no statistical difference between the two groups was detected (P = 0.45). Neither study detected a marked difference in terms of reported adverse effects from the two interventions.ConclusionBased on the results of our meta-analysis we conclude that there is no difference in visual acuity outcomes between atropine penalization therapy and occlusion therapy after 17 to 24 weeks of treatment in children aged 7–12 years. Further evidence to determine the efficacy of amblyopia therapy for an older patient population is required before studies comparing atropine penalization and occlusion therapy in patients older than 12 years can be performed. Atropine penalization therapy may cause more frequent minor adverse effects, such as light sensitivity, but in the clinical setting this needs to be balanced with the potential practical benefits of twice-weekly eye drops versus daily occlusion.FundingThe funding for this study was provided by the National Institute for Health Research (NIHR) and Health Education England (HEE).Plain Language SummaryA plain language summary is available for this article.Electronic supplementary materialThe online version of this article (10.1007/s40123-018-0151-9) contains supplementary material, which is available to authorized users.

Early monocular enucleation selectively disrupts neural development of face perception in the occipital face area

Retinoblastoma generally occurs before 5 years of age and often requires enucleation (surgical removal of one eye) of the cancerous eye. We have previously shown using behavioural methods that this disruption in binocular vision during the critical period of visual development results in impaired face perception. In this case series study, we sought to determine the underlying neural correlates of this face perception deficit by examining brain activity in regions of cortex that preferentially respond to visual images of faces and places in 6 adults who had one eye enucleated early in life due to retinoblastoma. A group of 10 binocularly-intact adult controls were recruited for comparison. Functional magnetic resonance imaging (fMRI) was conducted over two separate runs for each participant in one scanning session. Each run consisted of 6 blocks each of face, place, and object images. Region-of-interest analyses were conducted to locate face-preferential [fusiform face area (FFA), occipital face area (OFA)] and place-preferential [parahippocampal place area (PPA), transverse occipital sulcus (TOS)] regions-of-interest. Descriptive statistics are reported. Results. Enucleated adults exhibited reduced functional activation in face-preferential regions (left FFA, right OFA, left OFA), but similar activation within the face-preferential right FFA and the place-preferential regions (bilateral PPA and TOS). Conclusions. These results indicate that early monocular enucleation prevents robust development of late-maturing face processing capabilities and that this disruption is specific to face networks and not to networks supporting other visual image categories.

The challenging management of pediatric corneal transplantation: an overview of surgical and clinical experiences.

Pediatric keratoplasty is an immense challenge because of the technical complexity of the procedure and the high risk of rejection in young graft recipients. Our aim is to describe the major indications and appropriate timing of corneal transplantation intervention, including a report of our experience and surgical tips, in conjunction with the current literature. Review of the literature on indications for keratoplasty in pediatric patients classified as: congenital, traumatic and acquired non-traumatic opacities. We additionally explored the challenges corneal surgeons face in performing this type of surgery and review the most pressing transplant-related problems and their management. Outcomes after pediatric keratoplasty, in terms of visual development, restoration and clarity of the graft, are influenced by peri-operative local and systemic conditions and factors, and by intraoperative management of the transplantation procedure itself. Pediatric corneal transplantation is a critical tool for visual restoration and development in young patients with corneal opacities, particularly during the critical period of visual development. Successful management of the significant challenges associated with pediatric keratoplasty requires customized clinical and surgical management of each patient with particular attention paid to proper post-operative rehabilitation.

Sensory Eye Dominance in Treated Anisometropic Amblyopia.

Amblyopia results from inadequate visual experience during the critical period of visual development. Abnormal binocular interactions are believed to play a critical role in amblyopia. These binocular deficits can often be resolved, owing to the residual visual plasticity in amblyopes. In this study, we quantitatively measured the sensory eye dominance in treated anisometropic amblyopes to determine whether they had fully recovered. Fourteen treated anisometropic amblyopes with normal or corrected to normal visual acuity participated, and their sensory eye dominance was assessed by using a binocular phase combination paradigm. We found that the two eyes were unequal in binocular combination in most (11 out of 14) of our treated anisometropic amblyopes, but none of the controls. We concluded that the treated anisometropic amblyopes, even those with a normal range of visual acuity, exhibited abnormal binocular processing. Our results thus suggest that there is potential for improvement in treated anisometropic amblyopes that may further enhance their binocular visual functioning.

Training to improve contrast sensitivity in amblyopia: correction of high-order aberrations

Perceptual learning is considered a potential treatment for amblyopia even in adult patients who have progressed beyond the critical period of visual development because adult amblyopes retain sufficient visual plasticity. When perceptual learning is performed with the correction of high-order aberrations (HOAs), a greater degree of neural plasticity is present in normal adults and those with highly aberrated keratoconic eyes. Because amblyopic eyes show more severe HOAs than normal eyes, it is interesting to study the effects of HOA-corrected visual perceptual learning in amblyopia. In the present study, we trained twenty-six older child and adult anisometropic amblyopes while their HOAs were corrected using a real-time closed-loop adaptive optics perceptual learning system (AOPL). We found that adaptive optics (AO) correction improved the modulation transfer functions (MTFs) and contrast sensitivity functions (CSFs) of older children and adults with anisometropic amblyopia. When perceptual learning was performed with AO correction of the ocular HOAs, the improvements in visual function were not only demonstrated in the condition with AO correction but were also maintained in the condition without AO correction. Additionally, the learning effect with AO correction was transferred to the untrained visual acuity and fellow eyes in the condition without AO correction.

Amblyopia update: new treatments.

This review article is an update on the current treatments for amblyopia. In particular, the authors focus on the concepts of brain plasticity and their implications for novel treatment strategies for both children and adults affected by amblyopia. A variety of strategies has been developed to treat amblyopia in children and adults. New evidence on the pathogenesis of amblyopia has been obtained both in animal models and in clinical trials. Mainly, these studies have challenged the classical concept that amblyopia becomes untreatable after the 'end' of the sensitive or critical period of visual development, because of a lack of sufficient plasticity in the adult brain. New treatments for amblyopia in children and adults are desirable and should be encouraged. However, further studies should be completed before such therapies are widely accepted into clinical practice.

The role and efficacy of secondary intraocular lenses in the treatment of monocular infantile cataracts.

To determine if and when a secondary intraocular lens (IOL) can be beneficial to the successful treatment of a monocular infantile cataract. This retrospective study reviewed medical records of children undergoing treatment of a monocular congenital cataract from 1996 to 2009 at one pediatric ophthalmology practice. Patients had unilateral cataracts removed by age 8 months and a secondary IOL inserted prior to 6 years of age. At the final visit, the children had to perform linear Snellen visual acuity testing. Of 11 identified patients, 8 had treatment onset by age 4 months and 3 between 5 and 7 months of age. These 3 children had final acuities of 20/500 (n=2) and hand motion (n=1). Those undergoing treatment prior to age 5 months had Snellen acuities of 20/30 to 20/400. The best results were obtained by patients who were compliant with contact lenses and patching before insertion of a secondary IOL. If treatment of a monocular congenital cataract begins by 4 months of age (ie, the critical period for visual development) and patients remain compliant with occlusion therapy and an aphakic contact lens, then they will likely do well after IOL implantation. Furthermore, it appears that insertion of a secondary IOL will maintain vision that was established with a contact lens and patching and perhaps prevent deterioration that might still occur if compliance issues develop. However, secondary IOL placement will not dramatically improve the final visual result from that developed with occlusion and a contact lens.