Early binocular visual experience may improve binocular sensory outcomes in children after surgery for congenital unilateral cataract

Stereopsis following surgery in children with congenital and developmental cataracts: A systematic review and meta-analysis

We estimated the proportion of children with stereopsis following surgery in congenital and developmental cataracts by systematic review and meta-analysis and also considered the factors influencing stereopsis, such as intervention age and presence of strabismus. Stereopsis is directly related to quality of life, and investigating its levels following cataract surgery in children may help decide the right time to intervene, particularly in the context of brain plasticity. We conducted a systematic literature search using Scopus, PubMed, and Web of Science and found 25 case series, 3 cohorts, and 3 clinical trial studies from 1/1/1995 to 31/12/2020. Study-specific proportions of stereopsis from 923 children were pooled using a random-effects model, and stratified analyses were conducted based on intervention age and pre-existing strabismus as a confounder. We appraised the risk of bias using tools published by National Institutes of Health and evaluated publication bias with funnel plots and the Egger test. The pooled proportions of stereopsis based on 8 unilateral and 6 bilateral congenital cataract studies were 0.37 (95% CIs: [0.24, 0.53]) and 0.45 (95% CIs: [0.24,0.68]) when patients with preexisting strabismus were excluded as a confounder. When the intervention age was ≤6 months, proportions in unilateral congenital cataract group significantly increased to 0.52 (95% CIs: [0.37, 0.66]; P = 0.49) compared to 0.26 (95% CIs: [0.14, 0.44]; P = 0.16) otherwise. A similar increase in proportions was found when intervention age ≤4 months. In both unilateral and bilateral congenital cataract groups, proportions increased significantly when the confounder was excluded. Overall, proportions in bilateral congenital cataracts were significantly greater than unilateral cases (irrespective of confounder). Eight unilateral and 5 bilateral developmental cataract studies resulted in pooled proportions of 0.62 (95% CIs: [0.27, 0.88] and 0.82 (95% CIs: [0.4, 0.97]), respectively. Although proportions for bilateral developmental cataracts were greater than unilateral cataracts (irrespective of confounder), results were not statistically significant. Finally, proportions in unilateral developmental cataracts were significantly greater than unilateral congenital cataracts (Z = 7.413, P = 6.173694e-14). We conclude that surgical intervention within first 4-6 months can significantly affect postoperative outcomes in unilateral congenital cataracts. Analysis of existing data does not show a significant effect of intervention age on stereopsis outcomes for developmental cataracts.

Critical Periods in Vision Revisited

For four decades, investigations of the biological basis of critical periods in the developing mammalian visual cortex were dominated by study of the consequences of altered early visual experience in cats and nonhuman primates. The neural deficits thus revealed also provided insight into the origin and neural basis of human amblyopia that in turn motivated additional studies of humans with abnormal early visual input. Recent human studies point to deficits arising from alterations in all visual cortical areas and even in nonvisual cortical regions. As the new human data accumulated in parallel with a near-complete shift toward the use of rodent animal models for the study of neural mechanisms, it is now essential to review the human data and the earlier animal data obtained from cats and monkeys to infer general conclusions and to optimize future choice of the most appropriate animal model. Expected final online publication date for the Annual Review of Vision Science, Volume 8 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Visual outcomes of surgical and conservative treatment in children with small posterior polar cataracts and posterior lenticonus

AIM

To compare the visual outcomes of children with small (≤3 mm) posterior polar cataracts (PPC) and posterior lenticonus who had cataract extraction surgery with the visual outcomes of those who were managed conservatively.

METHODS

Children who initially had small PPC and posterior lenticonus who were followed up over 1-year period were retrospective reviewed in the study. Patients receiving surgery were compared with those receiving conservative therapy. The axial length, keratometry, refraction, best-corrected visual acuity (BCVA), and strabismus measurements were recorded. Lens morphology, i.e., the location, size, and depth of the cataract lesion, was measured with a Scheimpflug imaging system. To help control for baseline differences in the groups, patients were matched with controls by propensity score methodology.

RESULTS

The study evaluated 60 patients (30 in the surgery group and 30 in the conservative therapy group) after matching by propensity score. Patients who underwent cataract surgery showed greater BCVA improvements (0.36±0.24 logMAR) than patients who were treated without surgery (0.22±0.26 logMAR; P=0.036). Surgery was effective in patients with a rear projection length (RPL) less than 1.0 mm and a pretreatment BCVA worse than 0.52 logMAR.

CONCLUSION

Children with small PPC and posterior lenticonus who undergo cataract surgery experience greater BCVA improvements than those managed conservatively. Certain patients presenting with a RPL less than 1.0 mm and a pretreatment BCVA of 0.52 logMAR or worse may benefit from surgery.

A pilot randomized trial of contrast-rebalanced binocular treatment for deprivation amblyopia

BACKGROUND

Binocular neural architecture may be preserved in children with deprivation amblyopia due to unilateral cataract. The purpose of this study was to investigate whether a contrast-rebalanced binocular treatment, recently used with success to treat the interocular suppression and amblyopia in strabismic and anisometropic children, can contribute to rehabilitation of visual acuity in children with deprivation amblyopia secondary to monocular cataract.

METHODS

In a pilot randomized trial, 15 children (4-13 years of age) were enrolled and randomized to continue with their current treatment only (n = 7) or to continue with their current treatment and add contrast-rebalanced binocular iPad game play 5 hours/week for 4 weeks (n = 8). The primary outcome was change in visual acuity at 4 weeks.

RESULTS

Although 10 of 15 participants were patching, there was little change in visual acuity during the 3 months prior to enrollment. At the 4-week primary outcome visit, the mean improvement in visual acuity for the binocular game group was significantly greater than that for the current-treatment group (0.08 ± 0.10 logMAR vs -0.03 ± 0.05 logMAR [t_10.2 = 2.53, P = 0.03]). None of the children who had dense congenital cataract achieved improved visual acuity with binocular treatment.

CONCLUSIONS

In this study cohort, visual acuity improved over 8 weeks in children with unilateral deprivation amblyopia who played a binocular contrast-rebalanced binocular iPad game.

Cataract management in children: a review of the literature and current practice across five large UK centres

Congenital and childhood cataracts are uncommon but regularly seen in the clinics of most paediatric ophthalmology teams in the UK. They are often associated with profound visual loss and a large proportion have a genetic aetiology, some with significant extra-ocular comorbidities. Optimal diagnosis and treatment typically require close collaboration within multidisciplinary teams. Surgery remains the mainstay of treatment. A variety of surgical techniques, timings of intervention and options for optical correction have been advocated making management seem complex for those seeing affected children infrequently. This paper summarises the proceedings of two recent RCOphth paediatric cataract study days, provides a literature review and describes the current UK 'state of play' in the management of paediatric cataracts.

Effect of Timing of Initial Cataract Surgery, Compliance to Amblyopia Therapy on Outcomes of Secondary Intraocular Lens Implantation in Chinese Children: A Retrospective Case Series

Purpose

As a secondary analysis, we reassess the association of initial congenital cataract surgery times, compliance to amblyopia therapy, and visual outcomes for a long-term follow-up in a secondary IOL implantation.

Methods

Retrospective review of records of all infants with congenital cataracts who underwent secondary IOL implantation in the Eye and ENT Hospital of Fudan University from January 1, 2001, to December 31, 2007, and the minimum follow-up period was 5 years. Multiple regression analysis was used and the possible confounding factors were also analyzed to assess the effect on visual outcome.

Results

A total of 110 patients (male: 59.1%) were included. The median (min-max) age at cataract extraction and IOL implantation was 7.5 (3.0-15.0) and 35.0 (22.0-184.0) months, respectively, and the average follow-up period was 99.3 ± 23.6 months. The median (min-max) BCVA at final follow-up was 0.20 (0.01-1.00). Compliance to amblyopia therapy was none, poor, and good in 21.8%, 24.5%, and 53.6%, respectively. Postoperative BCVA [logMAR, median (min-max) 0.70 (0.00-2.00)] linearly decreased with increasing cataract extraction time (per month) (β = 0.04, 95% CI: 0.03-0.06, p < 0.0001) in multivariable models with laterality and compliance to amblyopia therapy adjusted. Good compliance to amblyopia therapy was associated with better BCVA (logMAR) at last follow-up (β = -0.40, 95% CI = -0.53 to -0.27, p < 0.0001) with laterality, opacity type, and extraction time adjusted.

Conclusions

For Chinese infants with congenital cataract, an earlier primary congenital cataract surgery at an age of 3 to 15 months is associated with a better visual outcome. Good compliance to amblyopia therapy was also significant to visual outcome.

Factors associated with stereopsis and a good visual acuity outcome among children in the Infant Aphakia Treatment Study

PurposeTo identify factors associated with stereopsis in children with good visual acuity after unilateral congenital cataract surgery in the Infant Aphakia Treatment Study.Patients and methodsInfants with a unilateral congenital cataract (n=114) were randomized to IOL implantation or contact lens correction after cataract surgery. At age 4.5 years, a masked examiner assessed HOTV acuity and stereopsis. Adherence to patching was assessed using 48-h recall telephone interviews and 7-day diaries throughout the first 5 years of life. Ocular motility was evaluated at age 5 years. Baseline, postoperative, and adherence findings were compared between patients with 20/40 or better acuity in their treated eyes with or without stereopsis.ResultsThirty (27%) of 112 patients who were evaluated at age 4.5 years had 20/40 or better acuity in their treated eye. Stereopsis was present on one or more tests in 15 of these 30 (50%) children. Baseline characteristics and postoperative findings did not differ between patients with or without stereopsis. Children with stereopsis were more likely to be orthotropic at distance (P=0.003) and were patched for fewer hours per day throughout the first 5 years of life and the difference increased over time (P<0.001). On average children with stereopsis were patched for 3.4 h/day during the first year of life and patching steadily decreased to 1.8 h/day by age 4 years.ConclusionAmong children with good vision following unilateral congenital cataract surgery, orthophoria and fewer hours of patching, particularly during years 2, 3, and 4, are associated with some evidence of stereopsis.

Stereopsis results at 4.5 years of age in the infant aphakia treatment study

PURPOSE

To determine whether stereopsis of infants treated for monocular cataracts varies with the type of optical correction used.

DESIGN

Randomized prospective clinical trial.

METHODS

The Infant Aphakia Treatment Study randomized 114 patients with unilateral cataracts at age 1-7 months to either primary intraocular lens (IOL) or contact lens correction. At 4.5 years of age a masked examiner assessed stereopsis on these patients using 3 different tests: (1) Frisby; (2) Randot Preschool; and (3) Titmus Fly.

RESULTS

Twenty-eight patients (25%) had a positive response to at least 1 of the stereopsis tests. There was no statistically significant difference in stereopsis between the 2 treatment groups: Frisby (contact lens, 6 [11%]; IOL, 7 [13%]; P = .99), Randot (contact lens, 3 [6%]; IOL, 1 [2%]; P = .62), or Titmus (contact lens, 8 [15%]; IOL, 13 [23%]; P = .34). The median age at surgery for patients with stereopsis was younger than for those without stereopsis (1.2 vs 2.4 months; P = .002). The median visual acuity for patients with stereopsis was better than for those without stereopsis (20/40 vs 20/252; P = .0003).

CONCLUSION

The type of optical correction did not influence stereopsis outcomes. However, 2 other factors did: age at surgery and visual acuity in the treated eye at age 4.5 years. Early surgery for unilateral congenital cataract and the presence of visual acuity better than or equal to 20/40 appear to be more important than the type of initial optical correction used for the development of stereopsis.

Preoperative visual acuity and contrast sensitivity in children with small, partial, or non-central cataracts

BACKGROUND

While there is clear evidence that dense central cataracts >3 mm diameter warrant prompt intervention to prevent deprivation amblyopia, guidelines for management of small, partial and non-central cataracts are not evidence-based. Consensus guidelines advise managing affected infants and preschool children by monitoring for possible progression in size or density and pharmacologic pupillary dilation, if indicated. Extraction is deemed necessary if the cataract progresses sufficiently to obscure the visual axis or if strabismus or nystagmus develops. We evaluated the long-term visual acuity outcome of the consensus guidelines and whether sensory testing during infancy and early childhood may be helpful in guiding treatment.

METHODS

A total of 40 consecutive children diagnosed with small, partial, or non-central cataracts at 1 week to 2.5 years of age were enrolled in a prospective study of forced-choice preferential looking visual acuity and contrast sensitivity development. Long-term visual acuity outcome was assessed by crowded HOTV or ETDRS at 4-11 years.

RESULTS

Of the 40 children managed by consensus guidelines, 24 (60%) had abnormal visual acuity at 4-11 years of age, including 9 (23%) who had moderate to severe visual impairment (20/80 or worse) in 1 or both eyes. Abnormal visual acuity and contrast sensitivity during development were predictive of abnormal long-term visual acuity outcomes.

CONCLUSIONS

Visual acuity and contrast sensitivity tests were sensitive to the effects of visual deprivation on the developing visual system and may be useful in early identification of children with small, partial, or non-central cataracts who could benefit from cataract extraction.

Fixation control and eye alignment in children treated for dense congenital or developmental cataracts

BACKGROUND

Many children treated for cataracts develop strabismus and nystagmus; however, little is known about the critical period for adverse ocular motor outcomes with respect to age of onset and duration.

METHODS

Children who had undergone extraction of dense cataracts by the age of 5 years were enrolled postoperatively. Ocular alignment was assessed regularly throughout follow-up. Fixation stability and associated ocular oscillations were determined from eye movement recordings at ≥5 years old. Multivariate logistic regression was used to evaluate whether laterality (unilateral vs bilateral), age at onset, and/or duration of visual deprivation were associated with adverse ocular motor outcomes and to determine multivariate odds ratios (ORs).

RESULTS

A total of 41 children were included. Of these, 27 (66%) developed strabismus; 29 (71%) developed nystagmus. Congenital onset was associated with significant risk for strabismus (OR, 5.3; 95% CI, 1.1-34.1); infantile onset was associated with significant risk for nystagmus (OR, 13.6; 95% CI, 1.6-302). Duration >6 weeks was associated with significant risk for both strabismus (OR, 9.1; 95% CI, 1.9-54.2) and nystagmus (OR, 46.2; 95% CI, 6.0-1005). Congenital onset was associated with significant risk for interocular asymmetry in severity of nystagmus (OR, 25.0; 95% CI, 2.6-649), as was unilateral cataract (OR, 58.9; 95% CI, 5.1-2318).

CONCLUSIONS

Laterality (unilateral vs bilateral) and age at onset were significant nonmodifiable risk factors for adverse ocular motor outcomes. Duration of deprivation was a significant modifiable risk factor for adverse ocular motor outcomes. The current study demonstrated that reduced risk for nystagmus and strabismus was associated with deprivation ≤6 weeks.

Effects of brief daily periods of unrestricted vision during early monocular form deprivation on development of visual area 2

PURPOSE

Providing brief daily periods of unrestricted vision during early monocular form deprivation reduces the depth of amblyopia. To gain insights into the neural basis of the beneficial effects of this treatment, the binocular and monocular response properties of neurons were quantitatively analyzed in visual area 2 (V2) of form-deprived macaque monkeys.

METHODS

Beginning at 3 weeks of age, infant monkeys were deprived of clear vision in one eye for 12 hours every day until 21 weeks of age. They received daily periods of unrestricted vision for 0, 1, 2, or 4 hours during the form-deprivation period. After behavioral testing to measure the depth of the resulting amblyopia, microelectrode-recording experiments were conducted in V2.

RESULTS

The ocular dominance imbalance away from the affected eye was reduced in the experimental monkeys and was generally proportional to the reduction in the depth of amblyopia in individual monkeys. There were no interocular differences in the spatial properties of V2 neurons in any subject group. However, the binocular disparity sensitivity of V2 neurons was significantly higher and binocular suppression was lower in monkeys that had unrestricted vision.

CONCLUSIONS

The decrease in ocular dominance imbalance in V2 was the neuronal change most closely associated with the observed reduction in the depth of amblyopia. The results suggest that the degree to which extrastriate neurons can maintain functional connections with the deprived eye (i.e., reducing undersampling for the affected eye) is the most significant factor associated with the beneficial effects of brief periods of unrestricted vision.

Binocular function in pseudophakic children

PURPOSE

The author reports the results of visual and binocular tests performed on patients who had primary insertion of intraocular lenses following the removal of cataracts in their childhood.

METHODS

Monocular and binocular tests were performed on 21 patients using the same equipment for sensory testing for binocularity on all patients before the history was abstracted from the clinical records. These patients were selected from a consecutive series and observed for a minimum of 5 years by their surgeons.

RESULTS

The mean age at surgery performed on the first eye was 6.3 years. The mean age at the date of the author's examination was 16.5 years and the mean length of follow-up was 10.3 years. All but 2 patients had motor alignment within 8 prism diopters of orthotropia at near. Fusion and some stereopsis was found in 15 patients, but only 4 of these demonstrated fine (60 seconds of arc or better) stereoacuity. Patients with fine versus gross stereoacuity were compared and found to be similar in type of cataract, age at first surgery, interval between surgeries, length of follow-up, and refraction, but different in the quality of best-corrected visual acuity.

CONCLUSION

Although satisfactory motor alignment, fusion, and some stereopsis is present in the majority of patients, fine stereoacuity is uncommon in pseudophakic children.

Oral reading after treatment of dense congenital unilateral cataract

BACKGROUND

Good long-term visual acuity outcomes for children with dense congenital unilateral cataracts have been reported after early surgery and good compliance with postoperative amblyopia therapy. However, treated eyes rarely achieve normal visual acuity, and there has been no formal evaluation of the utility of the treated eye for reading.

METHODS

Eighteen children previously treated for dense congenital unilateral cataract were tested monocularly with the Gray Oral Reading Test, 4th edition (GORT-4) at 7 to 13 years of age with the use of 2 passages for each eye, one at grade level and one at +1 above grade level. In addition, right eyes of 55 normal children age 7 to 13 served as a control group. The GORT-4 assesses reading rate, accuracy, fluency, and comprehension.

RESULTS

Visual acuity of treated eyes ranged from 0.1 to 2.0 logMAR and of fellow eyes from -0.1 to 0.3 logMAR. Treated eyes scored significantly lower than fellow and normal control eyes on all scales at grade level and at +1 above grade level. Monocular reading rate, accuracy, fluency, and comprehension were correlated with visual acuity of treated eyes (r(s) = -0.575 to -0.875, p < 0.005). Treated eyes with 0.1-0.3 logMAR visual acuity did not differ from fellow or normal control eyes in rate, accuracy, fluency, or comprehension when reading at grade level or at +1 above grade level. Fellow eyes did not differ from normal controls on any reading scale.

CONCLUSIONS

Excellent visual acuity outcomes after treatment of dense congenital unilateral cataracts are associated with normal reading ability of the treated eye in school-age children.

Laser in situ keratomileusis for treated myopic anisometropic amblyopia in children

PURPOSE

To evaluate the effects of laser in situ keratomileusis (LASIK) in decreasing myopic anisometropia in children with spectacles or contact lens intolerance and its validity in facilitating treatment of resultant myopic anisometropic amblyopia.

PATIENTS AND METHODS

LASIK was performed in 18 eyes of 18 children having myopic anisometropic amblyopia not successfully treated with the standard amblyopia treatment for 6 months. Children were followed up at 1 week, 1, 2, 6, 12, 18 and 24 months. Postoperative amblyopia therapy was continued with occlusion of the dominant eye for 6 h daily for the first 3 months and then for 4 h per day as long as possible.

RESULTS

The mean spherical equivalent refraction in the operated eye had reduced significantly from -9.08 ± 1.86D preoperatively to -0.97 ± 1.16D at 2 years postoperatively. The mean spherical equivalent in the non-operated fellow eye was -1.0 ± 1.15D preoperatively and -2.50 ± 1.15D at 2 years. The mean spherical equivalent myopic anisometropia was -7.75 ± 2.25D preoperatively and -0.50 ± 0.31D at 2 years, representing a 93.5% reduction in myopic anisometropia. The mean regression value was -2.28 ± 1.62D, however, 18 eyes (72%) were within 3.0D of the fellow eye. The mean BCVA was significantly improved from 0.72 ± 0.13 preoperatively to 0.47 ± 0.17 by 2 years after LASIK with amblyopia treatment.

CONCLUSION

LASIK is a safe and effective alternative method for correcting myopic anisometropic amblyopia, especially in children with spectacles or contact lens intolerance, with more better visual acuity and binocular vision.

Bilateral uneven cataracts in children: amblyopia management by sequential intraocular lens implantation

PURPOSE

To report on amblyopia management of children with bilateral uneven cataracts treated by sequential intraocular lens implantation.

METHODS

Children with bilateral uneven cataracts who needed bilateral cataract surgery were prospectively enrolled in Oxford Eye Center, Johannesburg, South Africa and Southwest Eye Hospital, Chong Qing, China. In the same patient, the amblyopic eye with the denser cataract underwent primary intraocular lens implantation, whereas the better eye was temporarily left aphakic as an alternative to patching. A secondary intraocular lens implantation was performed in the aphakic eye when best-corrected visual acuity in the amblyopic eye attained its best potential.

RESULTS

Thirteen children were included in this non-comparative study. Average age at surgery was 3.02+/-1.87 years with an average follow-up period of 9.35+/-5.23 years. In the amblyopic eyes, 10 out of 13 (77%) had less than 20/120 best-corrected visual acuity before amblyopia treatment. The optical penalization of the dominant eye (temporary aphakia) lasted on average 8.38+/-4.05 weeks. The best-corrected visual acuity of the amblyopic eye improved to 20/50 or better in six eyes (46%), and ranged from 20/60 to 20/200 in five eyes (38%); in remaining two eyes, the best-corrected visual acuity stayed below 20/200. Best-corrected visual acuity was restored to 20/30 or better following intraocular lens implantations in 12 of the dominant eyes (92%).

CONCLUSIONS

Optical penalization by temporary aphakia of the dominant eye is a convenient means for treating amblyopia in children with bilateral uneven cataracts.

The critical period for surgical treatment of dense congenital bilateral cataracts

INTRODUCTION

We examined the critical period for deprivation amblyopia in a cohort of patients with dense bilateral congenital cataracts to investigate the optimum timing for surgical treatment.

METHODS

Thirty-seven infants with dense bilateral congenital cataracts that were extracted by 31 weeks of age were enrolled prospectively. Visual acuity outcome was assessed at >/=5 years of age. We statistically evaluated which of 4 models provided the best fit to the data: (1) no change in visual acuity outcome with delay in surgery, (2) linear decline of outcome with delay, (3) a bilinear model in which a critical age exists after which outcome depends on delay, and (4) a bilinear model in which a critical age exists before which outcome depends on delay. In addition, we reviewed medical records for associated adverse outcomes, including strabismus, nystagmus, secondary membrane formation, and glaucoma.

RESULTS

A bilinear model with a critical age of 14 weeks fit the data better than a linear model (chi(2) = 14.7; p < 0.0006). During weeks 0-14, mean visual acuity decreased by 1 line with each 3 weeks' delay in surgery. From 14 to 31 weeks, visual acuity was independent the subject's age at surgery, averaging 20/80. Surgery after 4 weeks was associated with a greater prevalence of strabismus and nystagmus than surgery before 4 weeks, whereas surgery during the first 4 weeks was associated with a greater prevalence of secondary membrane formation and glaucoma.

CONCLUSIONS

We did not find a latent period for the treatment of children with dense bilateral congenital cataracts. Deprivation amblyopia may be minimized with early surgery for bilateral cataracts.

Visual outcome following the reduction or cessation of patching therapy after early unilateral cataract surgery

OBJECTIVE

To evaluate the impact on visual acuity of reducing or abandoning patching therapy during the first 6 years of life following early unilateral cataract surgery.

METHODS

We reviewed the medical records of 9 children with unilateral congenital cataracts who underwent cataract surgery when 6 weeks or younger. All had good compliance with optical correction until 6 years of age and with patching therapy until at least 12 months of age.

RESULTS

The children underwent cataract surgery at a mean (SD) age of 21.7 (9.5) days. At 12 months of age, the children were patched a mean (SD) of 6.7 (2.4) hours/d. Patching compliance declined steadily thereafter. By 6 years of age, they were only being patched a mean (SD) of 1.7 (2.0) hours/d. Four of the 9 children abandoned patching prior to the 6-year examination. Acuities improved or remained the same for 3 of these children but worsened for 1 child by 2 lines.

CONCLUSION

Our study suggests that some children who undergo early unilateral cataract surgery and are compliant with their optical correction and patching during early childhood can maintain a good visual outcome even if patching therapy is reduced or discontinued prior to their sixth birthday.

Cortical visual function in the rd12 mouse model of Leber Congenital Amarousis (LCA) after gene replacement therapy to restore retinal function

One eye of rd12 mice received a sub-retinal injection of a vector carrying normal human RPE65 cDNA at post-natal day 18, and at 6- and 13-months of age. Electroretinograms (ERGs) and visual-evoked potentials (VEPs) were recorded to luminance, and to spatially and temporally modulated stimuli to assess the consequences of delayed treatment on visual pathway function. Early treatment resulted in better overall retinal rescue and better rescue of cone-mediated function. VEPs to low temporal frequency luminance modulation were well preserved at all but the oldest treatment age and corresponded to predictions based on the amount of retinal rescue. In contrast, VEPs to high frequency spatially and temporally modulated stimuli were impaired even at the earliest age. These results provide further support that early treatment in human LCA will have the most hope for optimal visual performance.

The management of posterior polar cataract: the role of patching and grading

BACKGROUND

The milder form of posterior polar cataract is often discovered late in preschool children if secondary symptoms like strabismus are not present. The question addressed in this paper is: do such children still profit from orthoptic and surgical treatment?

PATIENTS AND METHODS

This was a retrospective study of the data from 13 patients, median age 4 years (range: 1 month to 12 years), with a mean follow-up of 4 years. Four changes to the red reflex were introduced.

RESULTS

Surgery followed from two weeks to three years after starting occlusion therapy. Before therapy, the best visual acuity was 0.3 and the worst 0.06 (median 0.16). A median of four years after starting therapy, the visual acuity ranged from 0.9 to 0.4 (median 0.6).

CONCLUSION

All milder cases profited from the treatment despite its late start. An earlier discovery would improve the prognosis. In any case, however, ophthalmologists should be encouraged to try patching before resorting to surgery.

Cataracts in children

Bilateral congenital cataract is the most common cause of treatable childhood blindness. Nuclear cataract is usually present at birth and is nonprogressive, whereas lamellar cataract usually develops later and is progressive. Surgery must be performed promptly in cases with dense congenital cataract; if nystagmus has developed, the amblyopia is irreversible. A treatment regimen based on surgery within 2 months of birth combined with prompt optical correction of the aphakia and aggressive occlusion therapy with frequent follow-up has been successful in unilateral and bilateral cases. Both anterior and posterior capsulorhexes are performed in most children. Intraocular lens implantation can be performed safely in children older than 1 year. Anterior dry vitrectomy is recommended in preschool children to avoid after-cataract. Opacification of the visual axis is the most common complication of cataract surgery in children. Secondary glaucoma is the most sight-threatening complication and is common if surgery is performed early. Life-long follow-up is essential in these cases.

Unilateral cataracts: is successful amblyopia therapy compatible with binocular vision?

BACKGROUND AND PURPOSE

Two case studies are used to illustrate the importance of balancing the postsurgical achievement of high-level visual acuity with the acquisition of stereopsis in cases of unilateral cataract. Traditional management will be reviewed and limited occlusion therapy will be discussed. A structured occlusion regime that allows for increased binocular opportunity is promoted for use upon cataract removal.

PATIENTS AND METHOD

Two cases are reviewed in which a unilateral cataract was removed and a full-time intensive patching schedule was followed.

RESULTS

Both patients reviewed have no measurable depth perception and are bothered by intractable diplopia.

CONCLUSION

Promoting good visual acuity in unilateral cataract management is the primary objective. Good visual acuity can be achieved with reduction of occlusion intensity in order to allow for some form of binocularity to develop, lowering the risk for strabismus and intractable diplopia.

Multiple sensitive periods in human visual development: Evidence from visually deprived children

Psychophysical studies of children deprived of early visual experience by dense cataracts indicate that there are multiple sensitive periods during which experience can influence visual development. We note three sensitive periods within acuity, each with different developmental time courses: the period of visually-driven normal development, the sensitive period for damage, and the sensitive period for recovery. Moreover, there are different sensitive periods for different aspects of vision. Relative to the period of visually driven normal development, the sensitive period for damage is surprisingly long for acuity, peripheral vision, and asymmetry of optokinetic nystagmus, but surprisingly short for global motion. A comparison of results from unilaterally versus bilaterally deprived children provides insights into the complex nature of interactions between the eyes during normal visual development.

Laser-assisted subepithelial keratectomy and photorefractive keratectomy versus conventional treatment of myopic anisometropic amblyopia in children

PURPOSE

To evaluate the visual and refractive results of photorefractive keratectomy (PRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopic anisometropia with amblyopia and contact lens (CL) intolerance in children.

SETTING

Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic.

METHODS

This prospective comparative study comprised 27 children with high myopic anisometropia and amblyopia. The mean age of the children was 5.4 years (range 4 to 7 years). Multizonal PRK (13 eyes) or LASEK (14 eyes) was performed in the more myopic eye under general anesthesia using the Nidek EC-5000 excimer laser. After surgery, the dominant eye was patched. The postoperative visual and refractive outcomes were analyzed; all children had a 2-year follow-up. The 27 children (Group A) were compared with a control group of 30 children (mean age 5.1 years) (Group B) in whom myopic anisometropia and amblyopia were treated conventionally by CLs and patching the dominant eye. The visual acuity and binocular vision outcomes in both groups were analyzed and compared.

RESULTS

In Group A, the mean spherical equivalent refraction was -8.25 diopters (D) +/- 2.37 (SD) (range -6.00 to -11.25 D) preoperatively and -1.61 +/- 0.73 D (range +0.50 to -2.25 D) postoperatively. The mean best corrected visual acuity (BCVA) was 0.23 +/- 0.21 preoperatively and 0.78 +/- 0.19 at 2 years. In Group B, the mean BCVA was 0.16 +/- 0.19 at the start of CL correction and amblyopia therapy and improved to 0.42 +/- 0.15 after 2 years. The mean BCVA at the final examination was significantly better in Group A (P<.05). Binocular vision improvement expressed by the proportion of patients who gained fusion and stereopsis was better overall in Group A (78%) than in Group B (33%) (P<.05). There were no complications postoperatively.

CONCLUSIONS

Photorefractive keratectomy and LASEK were effective and safe methods for correcting high myopic anisometropia and improving amblyopia in children aged 4 to 7 years who were CL intolerant. Visual acuity and binocular vision outcomes were better in children who received permanent surgical correction of anisometropia than in those who were treated conventionally by CLs.

Outcome after treatment of congenital unilateral cataract

PURPOSE

To evaluate long-term functional outcome after treatment of congenital unilateral cataract.

METHODS

The records of 30 consecutive children operated on before the age of 12 months at St. Erik's Eye Hospital over a 5-year period (1991-96) were reviewed retrospectively. The patients were followed until 4-9.5 years of age. Linear Snellen visual acuity (VA), occlusion therapy compliance, and the presence of nystagmus, strabismus and other complications are reported.

RESULTS

Six children achieved VA of 0.1 or better. They were all operated on before 3 months of age. Of the 12 infants operated on before 6 weeks of age, four have VA between 0.3 and 0.4 and eight have VA of finger counting or less. Four developed severe secondary glaucoma within 6 months of cataract extraction. Two of these had persistent fetal vasculature. Three eyes developing glaucoma became amaurotic. Occlusion therapy was abandoned before the age of 2.5 years in 21 children.

CONCLUSION

Good levels of VA were achieved only in children who underwent cataract surgery before 3 months of age and who adhered to the occlusion therapy schedule. Severe secondary glaucoma developed in four out of 12 children operated on within 6 weeks. Full compliance with the occlusion therapy programme was uncommon.