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

Through the Cat-Map Gateway: A Brief History of Cataract Genetics

Clouding of the transparent eye lens, or cataract(s), is a leading cause of visual impairment that requires surgical replacement with a synthetic intraocular lens to effectively restore clear vision. Most frequently, cataract is acquired with aging as a multifactorial or complex trait. Cataract may also be inherited as a classic Mendelian trait-often with an early or pediatric onset-with or without other ocular and/or systemic features. Since the early 1990s, over 85 genes and loci have been genetically associated with inherited and/or age-related forms of cataract. While many of these underlying genes-including those for lens crystallins, connexins, and transcription factors-recapitulate signature features of lens development and differentiation, an increasing cohort of unpredicted genes, including those involved in cell-signaling, membrane remodeling, and autophagy, has emerged-providing new insights regarding lens homeostasis and aging. This review provides a brief history of gene discovery for inherited and age-related forms of cataract compiled in the Cat-Map database and highlights potential gene-based therapeutic approaches to delay, reverse, or even prevent cataract formation that may help to reduce the increasing demand for cataract surgery.

Motion-Defined Form Perception in Deprivation Amblyopia

Purpose

The purpose of this study was to assess motion-defined form perception, including the association with clinical and sensory factors that may drive performance, in each eye of children with deprivation amblyopia due to unilateral cataract.

Methods

Coherence thresholds for orientation discrimination of motion-defined form were measured using a staircase procedure in 30 children with deprivation amblyopia and 59 age-matched controls. Visual acuity, stereoacuity, fusion, and interocular suppression were also measured. Fixation stability and fellow-eye global motion thresholds were measured in a subset of children.

Results

Motion-defined form coherence thresholds were elevated in 90% of children with deprivation amblyopia when viewing with the amblyopic eye and in 40% when viewing with the fellow eye. The deficit was similar in children with a cataract that had been visually significant at birth (congenital) and in children for whom the cataract appeared later in infancy or childhood (developmental). Poorer motion-defined form perception in amblyopic eyes was associated with poorer visual acuity, poorer binocular function, greater interocular suppression, and the presence of nystagmus. Fellow-eye deficits were not associated with any of these factors, but a temporo-nasal asymmetry for global motion perception in favor of nasalward motion suggested a general disruption in motion perception.

Conclusions

Deficits in motion-defined form perception are common in children with deprivation amblyopia and may reflect a problem in motion processing that relies on binocular mechanisms.

Congenital cataracts affect the retinal visual cycle and mitochondrial function: A multi-omics study of GJA8 knockout rabbits

Congenital cataracts are a threat to visual development in children, and the visual impairment persists after surgical treatment; however, the mechanisms involved remain unclear. Previous clinical studies have identified the effect of congenital cataracts on retinal morphology and function. To further understand the molecular mechanisms by which congenital cataracts affect retinal development, we analyzed retina samples from 7-week-old GJA8-knockout rabbits with congenital cataracts and controls by four-dimensional label-free quantification proteomics and untargeted metabolomics. Bioinformatics analysis of proteomic data showed that retinol metabolism, oxidative phosphorylation, and fatty acid degradation pathways were downregulated in the retinas of rabbits with congenital cataracts, indicating that their visual cycle and mitochondrial function were affected. Additional validation of differentially abundant proteins related to the visual cycle and mitochondrial function was performed using Parallel reaction monitoring and western blot experiments. Untargeted metabolome analysis showed significant upregulation of the antioxidant glutathione and ascorbic acid in the retinas of rabbits with congenital cataracts, indicating that their oxidative stress balance was not dysregulated. SIGNIFICANCE: Congenital cataracts in children can alter retinal structure and function, yet the mechanisms are uncertain. Here is the first study to use proteomics and metabolomics approaches to investigate the effects of congenital cataracts on retinal development in the early postnatal period. Our findings suggest that congenital cataracts have an impact on the retinal visual cycle and mitochondrial function. These findings give insight on the molecular pathways behind congenital cataract-induced visual function impairment in the early postnatal period.

Strabismus development after pediatric cataract surgery associated with age at surgery, intraocular lens implantation, and visual acuity outcome

PURPOSE

Approximately half of the children operated on for cataracts develop strabismus. We determined what factors predict its development.

METHODS

In a retrospective, cross-sectional study, children who underwent cataract surgery before age 5 between 2010 and 2017 in a tertiary center in Brazil were identified from medical records. Subsequently, patients were invited for an ophthalmological examination to assess visual acuity, refraction, and strabismus (constant or intermittent heterotropy of any magnitude). In addition, age at surgery, cataract laterality, intraocular lens implantation, surgical complications, nystagmus, anisometropia, and elapsed time between surgery and the present examination were assessed using logistic regression.

RESULTS

Surgery was performed in 74 eyes of 46 patients (21 males). The median age at surgery was 6.4 (3.7-29.6) months, and the interval between surgery and this examination was 32.5 (18.0-53.0) months. Strabismus was present in 33 (72%) patients, 35% had esotropia and 33% exotropia. One patient had strabismus surgery before the examination. Age at surgery (OR 0.95; p-value .018), IOL implantation (OR 0.08; p-value .027), and current visual acuity on the worse eye (OR 1.16; p-value .036) were associated with strabismus.

CONCLUSIONS

Strabismus development after pediatric cataract surgery is associated with age at surgery, intraocular lens implantation, and visual-acuity outcomes of the worse eye.

Strabismus and Nystagmus in Patients With Pediatric Cataracts: Study Using Insurance Claims Data

PURPOSE

To describe the characteristics and prevalence of strabismus and nystagmus in children diagnosed with cataracts using a national insurance claims database.

DESIGN

Population-based retrospective cohort study.

METHODS

Patients aged <13 years diagnosed with cataracts (traumatic cataracts excluded) and enrolled continuously in their health care program for ≥5 years after their first cataract diagnosis were identified in a retrospective review of 66 million charts in Optum's de-identified Clinformatics Data Mart Database between 2003 and 2015. Patients were categorized based on age of their first diagnosed cataract, and if cataract surgery was performed. Clinical and demographic factors associated with the occurrence of strabismus and nystagmus were evaluated.

RESULTS

Of 1636 children diagnosed with cataract, 434 (26.5%) and 109 (6.7%) were diagnosed with strabismus and nystagmus, respectively. Both strabismus and nystagmus were more common in those who underwent cataract surgery (P < .001) and in patients diagnosed with cataract at ≤12 months of age (P < .001). Survival analysis demonstrated that strabismus and nystagmus may be diagnosed 8 years after the initial cataract diagnosis. Cox proportional hazard regression analyses revealed strabismus was associated with cataract surgery, nystagmus, and the diagnosis with cataract at ≤12 months and cataract surgery at >12 months.

CONCLUSIONS

As strabismus and nystagmus occur more frequently in children diagnosed with cataracts necessitating cataract surgery, regular long-term follow-up is crucial for these children to monitor for the development of strabismus and nystagmus.

Primary versus secondary intraocular lens implantation following removal of congenital/de al of congenital/developmental catar elopmental cataracts: outcomes after acts: outcomes after at least 4 years

BACKGROUND

The aim of this study is to evaluate the long-term outcomes of primary and secondary intraocular lens (IOL) implantation following removal of congenital/developmental cataracts.

METHODS

One hundred and forty-four patients aged under 16 years who were followed up between 2003 and 2021 were analyzed retrospectively. The long-term results of children who underwent surgery before 2 years of age for congenital or developmental cataracts and underwent secondary IOL implantation after 2 years of age and those who underwent cataract surgery with primary IOL implantation after 2 years of age were compared. Patients with traumatic, secondary cataracts and cataracts due to ocular anomalies were not included in the study.

RESULTS

We evaluated 64 patients (mean age 9.5 ± 4.5 years) with secondary IOL implantation and 80 patients (mean age 12.8 ± 4.1 years) with primary IOL implantation in the study. Distance and near best-corrected visual acuities were significantly better in the primary IOL group than the secondary IOL group (p < 0.001). Incidence of strabismus after primary IOL surgery was significantly lower and presence of binocular vision was more often than the secondary IOL group (p = 0.002). There was no significant difference between the two groups in terms of refraction and myopic shift (p = 0.242, p = 0.172, respectively). Mean refractive changes were significant in unilateral cases of secondary IOL group and primary IOL group (p = 0.013, p = 0.049, respectively) and myopic shift was also greater in both groups of unilateral cases than the fellow eyes (p = 0.023, p = 0.012, respectively).

DISCUSSION

Visual outcomes and binocular vision were better, and the incidence of strabismus was also much less in the primary IOL group.

A dynamical method to objectively assess infantile nystagmus based on eye tracking. A pilot study

PURPOSE

The purpose of this research is to propose a new method for the easy, inexpensive and objective quantification of nystagmus using eye-tracking records collected during a simple reading task that could be implantable in clinical practice to assess patients with nystagmus.

METHODS

This is a prospective, observational pilot study. Eye movements of 4 nystagmus patients and 9 healthy children during a reading task (a paragraph with 82 words) on a 15'' monitor were collected and compared. Data are time series indicating the gaze position on the screen. Two quantifiers were proposed: IndS (based on the speed of movements) and IndF (based on the variation of the gaze trajectory).

RESULTS

The indices proposed reflect differences in the behavior of eye movements between the two groups. Nystagmus patients present higher values of IndS - indicating smaller number of slow movements (16% of movements with speeds <0.33 1/s for nystagmus and 85% for the control group, with p = 0.01) - and higher values of IndF - indicating higher gaze fluctuation (p = 0.01). Differences were not related with reading speed as show the mean and standard deviation: the nystagmus group required 115±45 s to complete the task and the control group 151±85 s; p = 0.73.

CONCLUSIONS

The proposed indices provide a new method that allows an objective assessment of nystagmus, with potential use in clinical and research practice to improve the follow-up of patients by monitoring the nystagmus over time or treatment.

Amblyopia and fixation eye movements

Amblyopia is a neurodevelopmental disorder caused by abnormal visual experience in early life that affects 3-5% of the population. Amblyopia results in a host of monocular and binocular visual afferent function deficits including reduced visual acuity, contrast sensitivity, depth perception, interocular suppression, and efferent function abnormalities such as unstable and inaccurate fixation. Conventional treatments such as patching therapy and newer dichoptic treatments are not always successful as 30-40% of patients experience recurrence/regression of amblyopia. There are numerous review articles focused on visual afferent function deficits and treatment modalities and outcomes in amblyopia. Recently, the advent of high spatial and temporal resolution eye trackers has spurred studies on fixation eye movements (FEMs) in healthy controls and neurologic and ophthalmic disorders. In this focused review, we will summarize studies evaluating FEM abnormalities in amblyopia. We will first describe the common devices and techniques used to quantify fixation abnormalities, and then highlight the importance of systematically evaluating the eye movements under different viewing conditions and describe the parameters crucial in assessing FEM abnormalities in amblyopia. We will summarize the evidence suggesting that FEM abnormalities are not limited to the amblyopic eye only but also affects the fellow eye and that FEM abnormalities can serve as biomarkers to predict the impact of amblyopia on visual functions. Beyond diagnosis, we will discuss the treatment and prognostic implications of the evaluation of FEM abnormalities in clinical practice.

Management of cataract surgery in Lowe syndrome

AIM

To evaluate the ophthalmic and anesthesiologic management of cataract surgery in children with Lowe syndrome receiving lens removal, the development and management of secondary glaucoma.

METHODS

This retrospective case series included 12 eyes of 6 children with genetically verified Lowe syndrome receiving cataract removal. Information regarding the type and duration of surgery and total anesthesia time were recorded. Additionally, intra- and postoperative complications were noted as well as clinical examinations such as visual acuity and funduscopy.

RESULTS

All children received simultaneous bilateral cataract surgery at the mean age of 8.98±3.58wk. Lensectomy combined with posterior capsulotomy and anterior vitrectomy was performed in all children. The mean time for cataract surgery per eye was 35.83±8.86min, whereas the total time of surgery was 153.33±22.11min. The mean extubation time and duration at recovery room was 42.33±22.60min and 130.00±64.37min, respectively. During surgery, a decrease of oxygen saturation below 93% was found in only one child. During the postoperative follow-up, nystagmus (6 children) and strabismus (5 children) was commonly found in contrast to no case of visual axis opacification. Secondary glaucoma developed in five eyes of three children, which was treated with topical eye drops in only one child. A trabeculectomy was performed in both eyes of one child, whereas removal of syechia and an iridectomy in one eye of one child.

CONCLUSION

Bilateral simultaneous cataract surgery under general anesthesia is a safe surgical procedure in Lowe syndrome children. The glaucoma screening with intraocular pressure measurements is crucial in the postoperative management of Lowe syndrome patients to avoid additional visual impairment.

Nystagmus in Down Syndrome – a Retrospective Notes Review

Introduction:

Nystagmus has been reported in up to 30% of people with Down Syndrome (DS), and yet is still not well understood. Our study aims to characterise the clinical features of patients with DS and nystagmus.

Methods:

A retrospective medical-records review was conducted of all patients with a diagnosis of DS and nystagmus seen at Moorfields Eye Hospital over a ten-year period.

Results:

Fifty-one subjects were identified, with complete data in 48. The mean age at presentation was 5.1 years (range 0–26 years). The mean binocular LogMAR visual acuity was 0.55(95%CI 0.53–0.57), mean refractive error was –1.8 Dioptre Sphere, DS (95% CI – 5.251.63) with –1.2 Dioptre Cylinder, DC (95% CI – 1.6–0.7). Ocular misalignment was found in 50% of patients. A diagnosis of Fusion Maldevelopment Nystagmus Syndrome (FMNS) was made in 6.3%, Infantile Nystagmus Syndrome (INS) in 8.4% and ABducting nystagmus/Inter-Nuclear Ophthalmoplegia (INO) in 2.1%. The descriptive term ‘Manifest Horizontal Nystagmus’(MNH) was used in the majority, highlighting the difficulties in clinically differentiating the subtypes of nystagmus in DS. Eleven patients had associated cataract. Additional diagnoses unrelated to DS were made in 10.4%.

Conclusions:

The most frequent type of nystagmus in our cohort was ‘presumed’ INS. This study highlights the importance of differentiating between FMNS and INS (with a latent component), so that further investigations can be performed as appropriate. Almost 25% had associated cataract, and a further 10% other diagnoses un-associated to DS. Despite INS being known to be associated with DS, further investigations may be required in a small subset with true INS after careful clinical assessment and use of eye movement recordings (where available).

A Retrospective Study on the Eye-Related Quality of Life, Functional Vision, and Their Determinants Among Children Following Congenital and Developmental Cataracts Surgery and Its Impact on Their Families Using the PedEyeQ

Objectives

To evaluate the eye-related quality of life (ER-QOL), functional vision, and their determinants in children following congenital and developmental cataract surgery, as the impact on their families, using the Pediatric Eye Questionnaire (PedEyeQ).

Materials and Methods

This was a retrospective cross-sectional study involving 107 children (aged 0–11 years) with congenital and developmental cataracts who had undergone surgery, as well as 59 visually healthy controls (aged 0–11 years). One parent for each child completed either the Proxy 0–4 PedEyeQ, the Proxy 5–11 PedEyeQ, or the Parent PedEyeQ, depending on their child's age. Mann-Whitney U and Kruskal-Wallis tests were then conducted to compare the differences between groups and to analyze their determinants.

Results

PedEyeQ scores were found to be lower in postoperative children with congenital and developmental cataracts compared with the control group across all study domains. The PedEyeQ Proxy 0 to 4 years' greatest mean difference was 27 points worse in the Functional Vision domain (95% CI −34 to −19; p &lt; 0.001). We also found that the occurrence of nystagmus (p &lt; 0.005) and strabismus (p &lt; 0.005) were the major factors affecting participants' functional vision. The PedEyeQ Proxy 5 to 11 years' greatest mean difference was 23 points worse in this same domain (95% CI −30 to −15; p &lt; 0.001), with nystagmus (p &lt; 0.05) being the main determinant herein. Parent PedEyeQ 0 to 4 years' greatest difference was 46 points worse on the Worry about their Child's Eye Condition domain (95% CI −57 to −36; p &lt; 0.001). Similarly, parents of children with ophthalmologic abnormalities, including nystagmus (p &lt; 0.001) and strabismus (p &lt; 0.05), were significantly more worried about their children's eye condition. Parent PedEyeQ 5 to 11 years' greatest difference was also found to be 30 points worse on the Worry about their Child's Eye Condition domain (95% CI −43 to −17; p &lt; 0.005).

Conclusions

Children who have undergone congenital and developmental cataract surgery experience a lower quality of life and reduced functional vision. Their families are also significantly and adversely affected herein. Thus, more attention is needed on these groups, with more focused measures being administered to both children and their families.

Evaluation of Fixational Behavior throughout Life

Background: To quantify development of gaze stability throughout life during short and long fixational tasks using eye tracking technology. Methods: Two hundred and fifty-nine participants aged between 5 months and 77 years were recruited along the study. All participants underwent a complete ophthalmological assessment. Fixational behavior during long and short fixational tasks was analyzed using a DIVE (Device for an Integral Visual Examination), a digital test assisted with eye tracking technology. The participants were divided into ten groups according to their age. Group 1, 0–2 years; group 2, 2–5 years; group 3, 5–10 years; group 4, 10–20 years; group 5, 20–30 years; group 6, 30–40 years; group 7, 40–50 years; group 8, 50–60 years; group 9, 60–70 years; and group 10, over 70 years. Results: Gaze stability, assessed by logBCEA (log-transformed bivariate contour ellipse area), improved with age from 5 months to 30 years (1.27 vs. 0.57 deg² for long fixational task, 0.73 vs. −0.04 deg² for short fixational task), while fixations tend to be longer (1.95 vs. 2.80 msec for long fixational tasks and 0.80 vs. 1.71 msec for short fixational tasks). All fixational outcomes worsened progressively from the fifth decade of life. Log-transformed bivariate contour ellipse area (0.79, 0.83, 0.91, 1.42 deg² for long fixational task and 0.01, 0.18, 0.28, 0.44 deg² for short fixational task, for group 7, 8, 9, and 10 respectively). Stimuli features may influence oculomotor performance, with smaller stimuli providing prolonged fixations. Conclusions: Fixational behavior can be accurately assessed from 5 months of age using a DIVE. We report normative data of gaze stability and duration of fixations for every age group. Currently available technology may increase the accuracy of our visual assessments at any age.

Preoperative Predictors for Esodeviation and Exodeviation after Cataract Surgery in Children

Purpose: For those children that went on to have strabismus surgery after cataract surgery, we sought to identify preoperative predictors for whether strabismus surgery would be for an esodeviation or for an exodeviation.Design: Retrospective studyMethods: Charts of patients <18 years who underwent cataract surgery were reviewed. Data from the first strabismus surgery after cataract surgery were reviewed. Statistical analysis was performed using T-test for continuous variable and chi-square test for categorical variable. A binomial logistic regression was performed to ascertain the effects of variables that were found to be significant.Results: 142 patients were identified having strabismus surgery. Type of deviation at first strabismus surgery was: Esodeviation: 72 (50.7%), exodeviation 55 (38.7%), and surgery for only vertical strabismus 15 (10.6%). Age at cataract surgery was an independent variable determining subsequent surgery for esodeviation or exodeviation. For each year increase in age at cataract surgery, the odds of having surgery for exotropia instead of esotropia increases by a factor of 1.620 (P = .005). Odds that strabismus surgery will be for exodeviation is 4.9 times higher in children who had cataract surgery at 1 year of age or greater as compared to children <1 year of age (P < .001).Conclusion: For those children who went on to have strabismus surgery after cataract surgery, younger age at cataract surgery increases the chance that subsequent strabismus surgery will be for an esodeviation. Those who had cataract surgery at an older age were more likely to have surgery for exotropia than for esotropia.

Clinical and Electrophysiological Outcomes After Eye Muscle Surgery in 81 Adults With Infantile Nystagmus Syndrome

PURPOSE

To characterize the effects of eye muscle surgery on patients older than 18 years with infantile nystagmus syndrome (INS) who have had only optical treatment.

METHODS

This was a prospective, single-center, interventional case series analysis of clinical and electro-phyisological data before and after surgery. Outcome measures included: clinical characteristics, surgical procedure, and preoperative and postoperative binocular best corrected visual acuity (BCVA) in the null position, anomalous head posture (AHP), contrast sensitivity, strabismic deviation, and nystagmus acuity function (NAFX). Postoperative data used were collected for a minimum of 12 months after surgery. Parametric and non-parametric statistical analysis of the outcome measures was performed.

RESULTS

Ages ranged from 18 to 72 years (average: 36 years) and follow-up from 12 to 74 months (average: 26 months). A surgical algorithm of nine separate procedures involving at least two recti muscles on each eye was used for each patient. Most patients had associated systemic and/or ocular diagnoses, including albinism (35%), amblyopia (23%), optic nerve or retinal disorders (48%), refractive error (80%), AHP (44%), aperiodicity (27%), and strabismus (69%). There were no serious surgical complications, with a reoperation rate of 12%. There were significant group mean increases in BVCA, AHP, contrast sensitivity, strabismic deviation, and NAFX after surgery. Sixty percent of patients who were legally ineligible for driving prior to surgery became eligible after eye muscle surgery.

CONCLUSIONS

Adult patients with INS showed sustained improvement in many afferent and efferent measures of visual function after eye muscle surgery. [J Pediatr Ophthalmol Strabismus. 2021;58(2):93-104.].

Visual experience dependent plasticity in humans

While sensitive periods in brain development have often been studied by investigating the recovery of visual functions after a congenital phase of visual deprivation in non-human animals, research in humans who had recovered sight after a transient phase of congenital blindness is still scarce. Here, we discuss the hypothesis put forward based on non-human primate work which states that the effects of experience increase downstream the visual processing hierarchy. Recent results from behavioral and neuroscience studies in sight recovery individuals are discussed in the context of research findings from permanently congenitally blind humans as well as from prospective studies in infants and children.

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.

Binocular reading in children following extraction of a dense congenital or infantile unilateral cataract

BACKGROUND

Reading relies on ocular motor function, requiring sequential eye movements (forward and regressive saccades). Binocularly discordant input from a dense congenital or infantile cataract is associated with ocular motor dysfunction and may affect the development of reading ability. The purpose of this study was to assess silent, binocular reading in children treated for unilateral congenital or infantile cataract.

METHODS

Twenty school-age children (age range, 7-13 years) treated for unilateral congenital (n = 9) or infantile (n = 11) cataract and 49 age-similar control children silently read a grade-appropriate paragraph during binocular viewing. Reading rate (words/min) and the number of forward and regressive saccades (per 100 words) were recorded using the ReadAlyzer.

RESULTS

Reading rate in children treated for a unilateral cataract did not differ significantly from controls (174 ± 59 words/min vs 195 ± 54 words/min; P = 0.1). However, they did have significantly more forward saccades (101 ± 33 saccades/100 words vs 87 ± 21 saccades/100 words; P = 0.03) but not regressive saccades (21 ± 14 saccades/100 words vs 16 ± 8 saccades/100 words; P = 0.1) compared with controls. Reading rate was not related to cataract type (congenital vs infantile), visual acuity outcome (poor vs good), or sensory fusion (fail vs pass; all P ≥ 0.1).

CONCLUSIONS

Reading rate of children treated for a dense unilateral cataract did not differ from that of controls. Increased forward saccades during reading may be due to fixation instability associated with fusion maldevelopment nystagmus prevalent in children following cataract extraction.

Successful visually guided eye movements following sight restoration after congenital cataracts

Sensitive periods have previously been identified for several human visual system functions. Yet, it is unknown to what degree the development of visually guided oculomotor control depends on early visual experience-for example, whether and to what degree humans whose sight was restored after a transient period of congenital visual deprivation are able to conduct visually guided eye movements. In the present study, we developed new calibration and analysis techniques for eye tracking data contaminated with pervasive nystagmus, which is typical for this population. We investigated visually guided eye movements in sight recovery individuals with long periods of visual pattern deprivation (3-36 years) following birth due to congenital, dense, total, bilateral cataracts. As controls we assessed (1) individuals with nystagmus due to causes other than cataracts, (2) individuals with developmental cataracts after cataract removal, and (3) individuals with normal vision. Congenital cataract reversal individuals were able to perform visually guided gaze shifts, even when their blindness had lasted for decades. The typical extensive nystagmus of this group distorted eye movement trajectories, but measures of latency and accuracy were as expected from their prevailing nystagmus-that is, not worse than in the nystagmus control group. To the best of our knowledge, the present quantitative study is the first to investigate the characteristics of oculomotor control in congenital cataract reversal individuals, and it indicates a remarkable effectiveness of visually guided eye movements despite long-lasting periods of visual deprivation.

Oculomotor deficits in children adopted from Eastern Europe

AIM

We aim to assess oculomotor behaviour in children adopted from Eastern Europe, who are at high risk of maternal alcohol consumption.

METHODS

This cross-sectional study included 29 adoptees and 29 age-matched controls. All of them underwent a complete ophthalmological examination. Oculomotor control, including fixation and saccadic performance, was assessed using a DIVE device, with eye tracking technology. Anthropometric and facial measurements were obtained from all the adopted children, to identify features of foetal alcohol spectrum disorders (FASD). Fixational and saccadic outcomes were compared between groups, and the effect of adoption and FASD features quantified.

RESULTS

Oculomotor performance was poorer in adopted children. They presented shorter (0.53 vs 1.43 milliseconds in the long task and 0.43 vs 0.82 in the short task) and more unstable fixations (with a bivariate contour ellipse area of 27.9 vs 11.6 degree² during the long task and 6.9 vs 1.3 degree² during the short task) and slower saccadic reactions (278 vs 197 milliseconds). Children with sentinel finding for FASD showed the worst oculomotor outcomes.

CONCLUSION

Children adopted from Eastern Europe present oculomotor deficits, affecting both fixation and saccadic skills. We highlight prenatal exposure to alcohol as the main cause for these deficits.

Simultaneous Bilateral Pediatric and Juvenile Cataract Surgery Under General Anesthesia: Outcomes and Safety

PURPOSE

To evaluate the surgical approach, outcome, and safety of bilateral simultaneous cataract surgery (BS-Cat) compared with unilateral cataract surgery (US-Cat) and bilateral 2-timed cataract surgery (BT-Cat) in children.

DESIGN

Retrospective, interventional case series.

METHODS

Setting: Department of Ophthalmology, Medical University, Vienna, Austria.

PARTICIPANTS

Children aged 0-18 years who received cataract extraction owing to a unilateral or bilateral cataract between January 2003 and December 2018 were included. Main Outcomes and Measures: Information regarding the type and duration of surgery and total anesthesia time were recorded. Additionally, intraoperative and postoperative complications including retreatments were evaluated.

RESULTS

A total of 220 eyes of 147 patients were included in this analysis (US-Cat: n = 74 patients; BS-Cat: n = 63 patients; BT-Cat: n = 10 patients). The mean age at surgery was 15.94 ± 27.10 months in the US-Cat group, 33.47 ± 58.20 months in the BS-Cat group, and 41.91 ± 55.09 months in the BT-Cat group. The main surgical approach was lensectomy combined with anterior vitrectomy ± IOL implantation (US-Cat: 98.65%; BS-Cat: 95.24%; BT-Cat: 100%; P = .08). Initial intraocular lens implantation was not commonly performed in all groups (US-Cat: 27.03%; BS-Cat: 23.02%; BT-Cat: 50.00%). The mean anesthesia time was shortest in the US-Cat (91.62 ± 26.12 min), followed by the BS-Cat (123.81 ± 30.11 min) and BT-Cat groups (186.00 ± 42.34 min; P < .001), contrary to the duration of surgery (US-Cat: 37.56 ± 15.69 min; BS-Cat: 32.33 ± 17.31 min; BT-Cat: 37.50 ± 18.67; P = .087). An accidental oxygen decrease below 93% was rare in all groups (US-Cat: 6.76%; BS-Cat: 17.46%; BT-Cat: 10.00%). Intraoperative surgical complications occurred rarely (P = .95) and involved mainly the iris. The number of postoperative complications (P = .17) and interventions (P = .10) was similar in all groups. Visual axis obscuration (US-Cat: 28.38%; BS-Cat: 23.81%; BT-Cat: 20.00%; P = .67) and glaucoma (US-Cat: 6.76%; BS-Cat: 15.87%; BT-Cat: 15.00%; P = .20) showed no difference between the groups. However, nystagmus was more pronounced in the BS-Cat group (US-Cat: 12.16%; BS-Cat: 49.21%; BT-Cat: 20.00%; P < .001), whereas strabismus was more pronounced in the US-Cat group (US-Cat: 68.92%; BS-Cat: 33.33%; BT-Cat: 40.00%; P < .001).

CONCLUSION

Simultaneous removal of bilateral cataract in children showed no statistically significant differences regarding intraoperative and postoperative complications when compared to unilateral and 2-timed bilateral cataract surgery. Anesthesia time was longer in simultaneous bilateral than in unilateral cataract surgery, but only by the surgery time of the second eye. However, prolonged anesthesia time was not accompanied by a decrease of oxygen saturation.

Impaired fine motor skills in children following extraction of a dense congenital or infantile unilateral cataract

PURPOSE

To evaluate fine motor ability in children treated for unilateral congenital or infantile cataract.

METHODS

Twenty-three children 3-13 years of age who were treated for unilateral congenital or infantile cataract and 38 age-similar control children were enrolled. Children completed five fine motor skills tasks (unimanual dexterity, bimanual dexterity, drawing trail, aiming, catching) from the Movement Assessment Battery for Children-2. Raw scores were converted into standardized scores, with higher scores indicating better performance.

RESULTS

Compared with controls, children treated for unilateral cataract scored lower on drawing trail (P = 0.009), aiming (P = 0.009), and catching (P < 0.001) but not on unimanual (P = 0.77) or bimanual dexterity (P = 0.31). Poorer affected eye visual acuity was moderately related to poorer performance for unimanual dexterity (r = -0.47; P = 0.025), bimanual dexterity (r = -0.50; P = 0.014), and catching (r = -0.41; P = 0.051). Those with a poor visual outcome (>0.6 logMAR) had worse performance than those with a good visual outcome (≤0.6 logMAR) for all tasks (all P values, 0.008-0.09) except aiming. Cataract type (congenital, 9; infantile, 14) and sensory fusion by Worth 4-Dot testing at 33 cm (pass, 10; fail, 13) had no effect on fine motor performance (all P values, 0.12-0.98).

CONCLUSIONS

In our study cohort, fine motor deficits were found in children treated for congenital or infantile unilateral cataract.

Glaucoma following cataract surgery in the first 2 years of life: frequency, risk factors and outcomes from IoLunder2

Background

We investigated glaucoma related adverse events, predictors and impact at 5 years following surgery in the IoLunder2 cohort

Methods

Population based observational cohort study of children undergoing cataract surgery aged 2 years or under between January 2009 and December 2010. Glaucoma was defined using internationally accepted taxonomies based on the consequences of elevated intraocular pressure (IOP). Glaucoma related adverse events were any involving elevated IOP. Multivariable analysis was undertaken to investigate potential predictors of secondary glaucoma with adjustment for within-child correlation in bilateral cataract. Unilateral and bilateral cataract were analysed separately.

Results

Complete follow-up data were available for 235 of 254, 93% of the inception cohort. By 5 years after primary cataract surgery, 20% of children with bilateral cataract and 12% with unilateral had developed secondary glaucoma. Glaucoma related complications had been diagnosed in 24% and 36% of children, respectively. Independent predictors of glaucoma were younger age at surgery (adjusted OR for reduction of week in age: 1.1, 95%C I 1.1 to 1.2, p<0.001); the presence of significant ocular comorbidity (adj OR 3.2, 95% CI 1.1 to 9.6, p=0.01); and shorter axial length (adj OR for each mm 1.7, 95% CI 10.0 to 1, p=0.05) for bilateral cataract. Shorter axial length was the single independent factor in unilateral disease (adj OR 9.6, 95% CI 1.7 to 52, p=0.009)

Conclusions

Both younger age at surgery (the strongest marker of ocular ‘immaturity’) and smaller ocular size (a marker of both immaturity and developmental vulnerability) can be used to identify those at greatest risk of glaucoma due to early life cataract surgery.

Optical Coherence Tomography Findings After Childhood Lensectomy

Purpose

To explore the impact of childhood lensectomy on posterior segment development.

Methods

Cross-sectional observational study at children's eye clinics at a tertiary referral center in London, UK. We included 45 children age 4 to 16 years with healthy eyes and 38 who had undergone lensectomy. We acquired posterior segment optical coherence tomography scans of both eyes. We used parametric and nonparametric tests in SPSS24 for the comparison of parameters between groups and within individuals; a P value less than 0.05 was considered significant. The main outcome measures were foveal pit depth and subfoveal choroidal thickness (CT). Secondary outcomes were inner and outer ring CT and photoreceptor layer parameters, macular and peripapillary retinal nerve fiber layer thickness.

Results

Foveal pit depth and subfoveal CT are significantly reduced in eyes that have undergone lensectomy compared with nonoperated eyes. Inner ring CT and outer ring CT are reduced. Foveal inner retinal layer thickness is increased. Mean inner retinal and outer nuclear layer thickness are not affected.

Conclusions

Childhood lensectomy is associated with a reduction in developmental foveal pit deepening and lack of developmental thickening of the posterior choroid. Mechanical and optical disruption of foveal and subfoveal choroidal development may affect structural foveal development after childhood lensectomy.

Evaluation of eye-related parameters and adverse events of rigid gas permeable contact lens and spectacles correction in infants with monocular aphakia after congenital cataract surgery: a retrospective clinical study

Background

Congenital cataract is currently one of the leading blindness-causing eye diseases in children. Surgical treatment only opens the visual pathway for children. The postoperative recovery of visual function is also dependent on effective optical correction and visual function training. In this study, we analyzed the changes in eye-related parameters, adverse events and the annual cost of rigid gas permeable contact lens (RGPCL) and spectacles correction in infants with monocular aphakia after congenital cataract surgery.

Methods

To analyze the postoperative visual acuity, strabismus, nystagmus, myopic shift, globe axial length growth, adverse events, patient adherence to patching, and annual cost for patients with unilateral congenital cataract who underwent cataract surgery. Rigid gas permeable contact lenses or spectacles were used to correct aphakia after congenital cataract.

Results

Of the 49 patients, 20 patients with unilateral aphakia who used RGPCL were in group 1. Group 2 comprised 14 patients with persistent fetal vasculature (PFV) who used RGPCL, and there were 15 patients with spectacles in group 3. In group 1, there were important improvements in visual acuity, strabismus and nystagmus. In groups 2 and 3, there were no significant improvements in visual acuity, strabismus or nystagmus. Patients with a good adherence to patching had better visual acuity after the operation than patients who did not, in groups 1 and 3. There were no significant differences in myopic shift or rate of globe axial length growth among the 3 groups. No patients in group 1 had ocular disease that affected visual acuity. The mean annual expenses of the RGPCL group was 3965 yuan, and the mean annual cost of spectacles was 1140 yuan to 2500 yuan.

Conclusion

RGPCL is a safe and effective optical correction method for patients with monocular aphakia after congenital cataract surgery. Spectacles are not an ideal optical correction. Using RGPCL to correct patients with PFV, the final visual acuity improved, but the difference was not statistically significant. There were no improvements in strabismus or nystagmus in patients with PFV.

Fixation instability during binocular viewing in anisometropic and strabismic children

PURPOSE

Strabismus or anisometropia disrupts binocularity and results in fixation instability, which is increased with amblyopia. Fixation instability has typically been assessed for each eye individually. Recently, vergence instability was reported in exotropic adults and monkeys during binocular viewing. We evaluated fixation instability during binocular viewing in children treated for anisometropia and/or strabismus.

METHODS

160 children age 4-12 years with treated esotropia and/or anisometropia (98 amblyopic, 62 nonamblyopic) were compared to 46 age-similar controls. Fixation instability was recorded during binocular fixation of a 0.3 deg diameter dot for 20 s using a 500 Hz remote video binocular eye tracker (EyeLink 1000; SR Research). The bivariate contour ellipse area (BCEA; log deg²) for fixation instability was calculated for each eye (nonpreferred, preferred) and for vergence instability (left eye position - right eye position). Best-corrected visual acuity, Randot Preschool stereoacuity, and extent of suppression scotoma (Worth 4-Dot) were also obtained.

RESULTS

When binocularly viewing, both amblyopic and nonamblyopic children treated for anisometropia and/or strabismus had larger fixation instability and vergence instability than controls. Amblyopia primarily added to the instability of the nonpreferred eye. Anisometropic children had less nonpreferred eye instability and vergence instability than those with strabismus or combined mechanism. Nonpreferred eye instability and vergence instability were related to poorer stereoacuity and a larger suppression scotoma. Preferred eye instability was not related to any visual outcome measure. No relationships were found with visual acuity.

CONCLUSIONS

Fixation instability and vergence instability during binocular viewing suggests that discordant binocular visual experience during childhood, especially strabismus, interferes with ocular motor development. Amblyopia adds to instability of the nonpreferred eye. Vergence instability may limit potential for recovery of binocular vision in these children.

Outcome of Pediatric Cataract Surgeries in a Tertiary Center in Switzerland

Purpose

To determine and to analyze the outcome of pediatric cataract surgery.

Methods

A retrospective chart review of individuals aged up to 10 years who underwent cataract surgery between January 1, 2004, and December 31, 2014, at the UniversityHospital Zurich, Switzerland.

Results

63 children (94 affected eyes) with bilateral (68/94) or unilateral (26/94) cataract were identified. Surgery was performed at a median age of 1.5 months (IQR: 1.3–2.6 months) for the aphakic group (45/94) and of 50.7 months (IQR: 38.0–78.4 months) for the IOL group (49/94). At the last follow-up visit (median 31.1 months, IQR: 18.4–50.2 months), visual acuity was better in bilateral than in unilateral cataract cases. Posterior capsular opacification (PCO) was diagnosed in 30.9% of eyes without a significant difference in the IOL and aphakic groups (p = 0.12). Aphakic glaucoma was diagnosed in 12/45 eyes at a median of 6.8 months (IQR 2.1–13.3 months) after surgery. Microcornea (5/12) and anterior segment anomalies (8/12) were associated with glaucoma development (p < 0.05).

Conclusion

Laterality and timing of surgery influence the outcome of pediatric cataract surgery. PCO was the most frequent postoperative complication. Aphakic glaucoma is often associated with ocular developmental abnormalities and a poor visual outcome.

Timing and approaches in congenital cataract surgery: a four-year, two-layer randomized controlled trial

AIM

To compare visual prognoses and postoperative adverse events of congenital cataract surgery performed at different times and using different surgical approaches.

METHODS

In this prospective, randomized controlled trial, we recruited congenital cataract patients aged 3mo or younger before cataract surgery. Sixty-one eligible patients were randomly assigned to two groups according to surgical timing: a 3-month-old group and a 6-month-old group. Each eye underwent one of three randomly assigned surgical procedures, as follows: surgery A, lens aspiration (I/A); surgery B, lens aspiration with posterior continuous curvilinear capsulorhexis (I/A+PCCC); and surgery C, lens aspiration with posterior continuous curvilinear capsulorhexis and anterior vitrectomy (I/A+PCCC+A-Vit). The long-term best-corrected visual acuity (BCVA) and the incidence of complications in the different groups were compared and analyzed.

RESULTS

A total of 57 participants (114 eyes) with a mean follow-up period of 48.7mo were included in the final analysis. The overall logMAR BCVA in the 6-month-old group was better than that in the 3-month-old group (0.81±0.28 vs 0.96±0.30; P=0.02). The overall logMAR BCVA scores in the surgery B group were lower than the scores in the A and C groups (A: 0.80±0.29, B: 1.02±0.28, and C: 0.84±0.28; P=0.007). A multivariate linear regression revealed no significant relationships between the incidence of complications and long-term BCVA.

CONCLUSION

It might be safer and more beneficial for bilateral total congenital cataract patients to undergo surgery at 6mo of age than 3mo. Moreover, with rigorous follow-up and timely intervention, the postoperative complications in these patients are treatable and do not compromise visual outcomes.

Visual outcomes of dense pediatric cataract surgery in eastern China

Purpose

To evaluate the visual outcomes of dense pediatric cataract surgery in eastern China.

Methods

Medical records of children who underwent surgery for dense unilateral or bilateral pediatric cataract in Shandong Provincial Hospital between January 2007 and December 2012 were collected. Patients who cooperated with optical correction and aggressive patching of the sound eye and who had a minimum postoperative follow-up of more than 2 years were included. Risk factors for poor visual outcomes were analyzed.

Results

Of the 105 eligible patients (181 eyes), 76 had bilateral cataract, and 29 unilateral. With a mean follow up of 46.77 mo (range 24.0~96.0 mo), the final best corrected visual acuity (BCVA) of 158 eyes were recorded, and 4.43% (7/158) achieved 0.1 logarithm of the minimum angle of resolution (logMAR) or better; 15.19% (24/158) obtained a BCVA between 0.1 logMAR and 0.3 logMAR; 18.99%, (30/158) between 0.3 logMAR and 0.5 logMAR; 46.84% (74/158), between 0.5 logMAR and 1 logMAR; 14.55%, worse than 1 logMAR. The mean BCVA of the patients who underwent lensectomy before 3 months of age was significantly better than that of patients who underwent lensectomy between 3 and 12 months (p = 0.001). In the same lensectomy age groups, the final BCVA of the children in the bilateral and unilateral groups did not differ significantly (P>0.05). Lensectomy after 3 months of age, postoperative complications, strabismus and nystagmus were shown to be risk factors for poor visual outcomes.

Conclusions

Lensectomy before 3 months of age, IOL implantation, proper managing of postoperative complications, early optical correction and aggressive postoperative patching of the sound eye would increase the final BCVA for patients with dense pediatric cataract.

Congenital Cataract Screening

Congenital cataract is a leading cause of visual deprivation which can damage the developing visual system of a child; therefore early diagnosis, management and long-term follow-up are essential. It is recommended that all neonates be screened by red reflex examination at birth and suspected cases be referred to ophthalmic centers. Early surgery (<6 weeks of age, based on general neonatal health) is important for achieving the best visual outcome particularly in unilateral cases. In bilateral cases, surgery is highly recommended before appearance of strabismus or nystagmus (<10 weeks of age) with no longer than a one-week interval between the fellow eyes. Parents should be informed that surgery is a starting point and not the endpoint of treatment. Appropriate postoperative management including immediate optical correction in the form of aphakic glasses or contact lenses, or intraocular lens (IOL) implantation at the appropriate age (>1 year) is highly recommended. After surgery, amblyopia treatment and periodic follow-up examinations should be started as soon as possible to achieve a satisfactory visual outcome. Practitioners should consider the possibility of posterior capsular opacity, elevated intraocular pressure and amblyopia during follow-up, especially in eyes with microphthalmia and/or associated congenital anomalies. All strabismic children should undergo slit lamp examination prior to strabismus surgery to rule out congenital lens opacities. From a social point of view, equal and fair medical care should be provided to all children regardless of gender.

Congenital and Developmental Cataracts: Focus on Strabismus Outcomes at Long-Term Follow-Up

PURPOSE

To evaluate the incidence of strabismus in congenital and developmental cataract surgery in patients with a follow-up longer than five years.

METHODS

All patients with congenital and developmental cataracts observed from 1996 to 2013 with a follow-up longer than five years were retrospectively included.

RESULTS

We included 117 patients (58 females and 59 males, mean age 0.62±0.3 years, 160 eyes) with congenital cataracts and 73 patients (32 females and 41 males, mean age 6.63±0.7 years, 121 eyes) with developmental cataracts. Before cataract surgery, strabismus was present in 88 patients with congenital cataracts (75.2%) and in 30 patients with developmental cataracts (41.1%) (p=0.01). After a follow-up of 9.26±1.3 years (range, 5-14 years), a significantly greater incidence of strabismus was observed after surgery only in patients with unilateral congenital cataracts who underwent cataract removal and primary IOL implantation (p=0.02). Distance BCVA and near BCVA were better after surgery for developmental cataracts (p<0.05). Presence of binocular vision was more frequent after surgery for developmental cataracts (p=0.001).

CONCLUSION

Incidence of strabismus and postsurgical onset of strabismus at long-term follow-up was greater in patients with congenital cataracts.

Long-term visual outcome of congenital cataract at a Tertiary Referral Center from 2004 to 2014

Purpose

To assess the long-term visual acuity (VA) outcome after congenital cataract surgery at Imam Hossein Medical Center (Tertiary Referral Center) (2004–2014).

Methods

In this descriptive study, records of 120 patients with a history of congenital cataract surgery were studied. Those with traumatic, metabolic cataract, aged <5 years at the last visit who were not able to respond VA testing accurately and follow-up < 6 months were excluded. Cases with incomplete files were recalled and reexamined. Finally, the records of 42 patients (71 eyes) were included.

Results

In this study, 20 males and 22 females with a mean age of 11.80 ± 6 years at their last visit were studied. Bilateral and unilateral cataract was seen in 69% and 31% of cases, respectively. Posterior and anterior subcapsular opacity was the most common (53.70%) and rarest (1.90%) type of congenital cataract, respectively. The mean age at the time of operation and surgical interval was 65 ± 66.6 (range: 1–200) and 12.9 ± 23.5 (range: 0–96) months, respectively. The most common method of refractive error correction was pseudophakia plus glasses (56.3%) with the mean best corrected visual acuity (BCVA) of 0.29 ± 0.28 LogMAR., The mean BCVA was 0.7 ± 0.53 LogMAR for aphakic patients correcting by glasses. In our study, amblyopia (56%), glaucoma (23.90%), and posterior capsular opacity (16.40%) were observed during their follow-ups on an average of 76 ± 65 months (median: 60, range: 6–240). Unilateral cataract, aphakia, nystagmus, female gender, and strabismus were risk factors of VA loss.

Conclusion

Based on our results, 56% of cases showed amblyopia. It could be due to late operation (especially in unilateral cases), longer surgical interval between two eyes, and no compliance of amblyopia therapy. Early detection through screening may reduce the rate of amblyopia. Refractive errors, visual acuity, amblyopia, glaucoma, posterior capsular opacity, and compliance of amblyopia therapy should be checked regularly at follow-up visits.

Long-Term Visual Outcomes of Secondary Intraocular Lens Implantation in Children with Congenital Cataracts

Aim

The aim of this study was to evaluate the long-term visual outcomes and factors affecting visual results in children undergoing secondary intraocular lens (IOL) implantation following primary congenital cataract extraction.

Methods

Children with congenital cataracts who underwent secondary IOL implantation for aphakia at the Eye and ENT Hospital of Fudan University between January 1, 2001, and December 31, 2007, were retrospectively reviewed. One eye was randomly selected in children with bilateral cataracts. Laterality, type of cataract (total or partial opacity), sex, age at primary and secondary surgeries, visual axis opacity (VAO), compliance with amblyopia therapy, postoperative ocular complications, refractive error, ocular alignment, and best corrected visual acuity (BCVA) at last follow-up were recorded; potential factors that might have affected the visual results were evaluated.

Results

Seventy-six bilateral and 34 unilateral congenital cataract cases were analyzed; the mean ages of the children were 12.70±5.06 and 12.50±2.71 years at final follow-up, the mean follow-up periods from IOL implantation were 94.93±24.22 and 109.09±18.89 months, and the mean BCVA (Log MAR) values were 0.51±0.37 and 1.05±0.46, respectively. Final BCVA after secondary IOL implantation was significantly associated with laterality, type of cataract, age at primary cataract extraction, compliance with amblyopia therapy, and refractive correction after surgery. No significant associations were found between BCVA and sex, age at secondary IOL implantation, VAO, or other ocular complications. The most common ocular complications were VAO and elevated intraocular pressure after surgery. There were no other complications, with the exception of one eye with IOL dislocation.

Conclusions

The results indicate that the important determinants of long-term visual outcomes in children with congenital cataracts undergoing secondary IOL implantation are laterality, cataract type, age at initial cataract extraction, compliance with amblyopia therapy, and refractive error.

Strabismus in infants following congenital cataract surgery

PURPOSE

This study aimed to determine the incidence and characteristics of strabismus following congenital cataract surgery in infants.

MATERIALS AND METHODS

Patients aged <12 months who underwent surgery for congenital cataract and were followed-up for ≥1 years were included. Patients that had strabismus prior to surgery were excluded. Data regarding gender, cataract laterality, morphology, and density, age at the time of cataract surgery, ocular motility post surgery, and the presence of nystagmus were retrospectively obtained from the patients' records.

RESULTS

The study included 79 patients (48 male and 31 female). Unilateral surgery was performed in 14 of the patients, versus bilateral surgery in 65. Strabismus did not occur post surgery in 32 (40.5 %) of the patients (group 1), whereas 47 (59.5 %) (group 2) developed strabismus following surgery. The patients in group 1 were followed-up for a mean 50.7 ± 38.5 months, versus 50.3 ± 39 months in group 2. Mean age at the time of cataract surgery in groups 1 and 2 was 3.6 ± 1.9 years and 4.6 ± 3.2 months respectively. Mean duration of time between cataract surgery and the development of strabismus was 13.3 ± 13 months (range: 1-60 months). Unilateral cases were more prone to develop strabismus, which was statistically significant (p = 0.028). Age at the time of cataract surgery, gender, cataract density, the occurrence of aphakic glaucoma, the presence of nystagmus, and additional ocular surgery were not significantly associated with the development of strabismus.

CONCLUSION

Strabismus develops more frequently in children undergoing cataract surgery. In the present study strabismus occurred in more of the patients that underwent unilateral surgery. Based on the present findings, we think that long-term careful follow-up to monitor the development of strabismus is required in all infants undergoing cataract surgery, especially unilateral cases.

Aetiology of infantile nystagmus

PURPOSE OF REVIEW

Mechanisms underlying infantile nystagmus are unclear. The aim of this review is to outline recent developments in understanding the aetiology of infantile nystagmus.

RECENT FINDINGS

There have been advances in understanding mechanisms underlying idiopathic infantile nystagmus, which has progressed through determining the role of the FRMD7 gene in controlling neurite outgrowth, and albinism, in which recent models have investigated the possibility of retinal miswiring leading to nystagmus. We also briefly review aetiology of infantile nystagmus in afferent visual deficits caused by ocular disease, and PAX6 mutations. Improved phenotypical characterization of all these infantile nystagmus subtypes has been achieved recently through high-resolution retinal imaging using optical coherence tomography. Several new hypotheses proposing common mechanisms that could underlie various infantile nystagmus subtypes are also highlighted.

SUMMARY

Although there is still no consensus of opinion regarding the mechanisms causing infantile nystagmus, identification of new genes and determining their cellular function, phenotypical characterization of genetic subtypes, and improvements in animal models have significantly advanced our understanding of infantile nystagmus. These recent developments pave the way to achieving a much clearer picture of infantile nystagmus aetiology in the future.

Nystagmus and related fixation instabilities following extraction of unilateral infantile cataract in the Infant Aphakia Treatment Study (IATS)

PURPOSE

To study eye movements in a large group of children after the removal of unilateral infantile cataract, and to compare fixation instabilities between treatment groups with or without IOL implantation.

METHODS

The Infant Aphakia Treatment Study (IATS) is a randomized, multicenter clinical trial comparing IOL to contact lens (CL) treatment with a unilateral infantile cataract in participants who underwent cataract surgery at 1 to 6 months of age. At age 4.5 years, eye movements were recorded in 103 participants, using a high-speed video camera while the child performed a fixation task. The recordings were inspected by masked readers for the presence of fixation instabilities (nystagmus and saccadic oscillations).

RESULTS

Overall, fixation instabilities were observed in 50 (60%) of 83 children who had evaluable recordings, with no differences between treatment groups (27 [64%] of 42 in the IOL group, 23 [56%] of 41 in the CL group; P = 0.51). Nystagmus was seen in 38% and saccadic oscillations in 31%, with no differences between treatment groups (P > 0.33). Children without a fixation instability had better visual acuity (P = 0.04).

CONCLUSIONS

Nystagmus and saccadic oscillations are well-known consequences of infantile cataracts, presumably the result of visual deprivation during the critical period of visual development. After early cataract extraction, successful optical correction may reduce further form deprivation and minimize the incidence of these fixation instabilities. In this study, no differences in the presence of fixation instabilities were found between the two treatment strategies (CL or IOL) for optical correction after cataract removal. (ClinicalTrials.gov number, NCT00212134.).

Factors associated with strabismus after cataract extraction and primary intraocular lens implantation in congenital cataracts

AIM

To evaluate factors associated with the development of strabismus after cataract extraction and primary intraocular lens implantation.

METHODS

The medical records of 122 patients, aged 1.5mo to 9y, who had undergone cataract extraction with primary intraocular lens implantation between January 1993 and August 2011 were reviewed. Fourteen patients (17 eyes) with strabismus before cataract surgery were excluded. Patients were divided into those with congenital bilateral cataracts (64 patients, 128 eyes) and those with unilateral cataracts (44 patients, 44 eyes). The associations between the development of strabismus and age at cataract surgery, pre- and post-cataract extraction corrected distance visual acuity (CDVA), interocular CDVA difference, nystagmus, surgical method, and secondary cataract were evaluated.

RESULTS

Factors significantly associated with the development of strabismus included age at cataract surgery (≤1y), preoperative mean CDVA ≤20/100, presence of nystagmus in the bilateral cataract group and postoperative interocular CDVA difference >20/70 in the unilateral group. Postoperative CDVA ≤20/100 and preservation of posterior capsule, and presence of secondary cataract were significant factors in both groups.

CONCLUSION

Children with congenital cataracts should be monitored carefully after cataract surgery for the development of strabismus, especially when they underwent surgery at age ≤1y, and they have nystagmus, large postoperative interocular CDVA difference, poor preoperative and postoperative CDVA, preservation of the posterior capsule, or secondary cataract.

Advances in the management of the surgical complications for congenital cataract

The greatest concern in children with cataracts is irreversible visual loss. The timing of congenital cataract surgery is critical for the visual rehabilitation. Cataract surgery in children remains complex and challenging. The incidence of complications during or after operation is higher in children than adults. Some complications could be avoided by meticulous attention to surgical technique and postoperative care, and others were caused by more exuberant inflammatory response associated with surgery on an immature eye or the intrinsic eyes abnormalities. Utilizing of advanced techniques and timely applying topical corticosteroids and cycloplegic agents can reduce the occurrence of visual axis opacification. Operation on children with strabismus or nystagmus, and applying occlusion therapy on amblyopic eyes can balance the visual inputs to the two eyes. Diagnosis of glaucoma following congenital cataract surgery requires lifelong surveillance and continuous assessment of the problem. So cataract surgeries in children are not the end of journey, but one step on the long road to visual rehabilitation. This paper describes recent evidence from the literature regarding the advance of management after congenital cataract surgery.