Factors affecting the benefit of glasses alone in treating childhood amblyopia: an analysis of PEDIG data

BACKGROUND

To evaluate factors associated with better outcomes from optical treatment alone in amblyopic children from 3 up to 7 years.

METHODS

Data extracted from two studies with similar protocols, Amblyopic Treatment Studies 5 (n = 152) and 13 (n = 128) from the Pediatric Eye Disease Investigator Group database, were used to determine by regression analysis the factors associated with improvements in visual acuity in the amblyopic eye, inter-ocular visual acuity difference and stereoacuity. Input variables were aetiology of amblyopia (anisometropic, strabismic and combined-mechanism amblyopia), treatment compliance, visual acuity, interocular visual acuity difference, stereoacuity, tropia size at distance and near, age and refractive error at baseline.

RESULTS

Despite the range of clinical factors considered, our models explain only a modest proportion of the variance in optical treatment outcomes. The better predictors of the degree of optical treatment success in amblyopic children are visual acuity of the amblyopic eye, interocular visual acuity difference, stereoacuity, treatment compliance and the amblyopic eye spherical-equivalent refractive error. While the aetiology of the amblyopia does not exert a major influence upon treatment outcome, combined-mechanism amblyopes experience the smallest improvement in visual acuity, tropia and stereoacuity and may need longer optical treatment periods.

CONCLUSIONS

While results identify the factors influencing optical treatment outcome in amblyopic children, clinicians will be unable to predict accurately the benefits of optical treatment in individual patients. Whether this is because relevant clinical or non-clinical factors (e.g. nature and volume of daily activities undertaken) influences the outcomes from optical treatment has not yet been identified and remains to be discovered.

Impact of Degraded Optics on Monocular and Binocular Vision: Lessons from Recent Advances in Highly-Aberrated Eyes

PURPOSE

Optical imperfections of the eye, characterized by higher-order wavefront aberrations, are exaggerated in corneal disease (e.g., keratoconus) and iatrogeny (e.g., keratorefractive surgery for myopia correction, keratoplasty for optical clarity restoration). This article reviews the recent advances on this topic for a comprehensive understanding of how optical degradations in disease models impact retinal image quality and monocular and binocular visual performance.

METHODS

Published literature over the last decade on retinal image quality and/or monocular and binocular visual functions with corneal irregularity was reviewed based on their relevance to the current topic, study population and strength of study design. The literature was summarized into four themes: 1) wavefront errors and retinal image quality of highly aberrated eyes, 2) monocular and binocular vision loss consequent to degraded optics and visual strategies to optimize performance, 3) impact of optical correction modalities on visual performance and 4) implications for clinical management of patients.

RESULTS

Across the 46 articles reviewed, the results clearly indicated that an increase in higher-order aberrations across these conditions had a significant negative impact on the patient's retinal image quality, and monocular and binocular visual functions. Interocular differences in retinal image quality deteriorated visual performance more than an overall worsening of image quality bilaterally. Minimizing optical degradation using rigid contact lenses and adaptive optics technology significantly improves retinal image quality and monocular and binocular vision, but performance remains sub-optimal relative to age-similar healthy controls.

CONCLUSION

Corneal disease and iatrogeny are useful models to understand the impact of optical degradation on retinal image quality and visual performance. Clinical management will greatly benefit from equalizing retinal image quality of both eyes of these patients. Future studies that deepen our understanding of the structure-function relation in these conditions are desirable for advancing vision science in this area and for developing novel clinical management strategies.

Repeatability, reproducibility and interocular difference in the assessments of optic nerve OCT in children- a Swedish population-based study

Background

The aim was, first, to collect normative data of the optic nerve head and the peripapillary retinal nerve fibre layer (RNFL) thickness assessed with Cirrus SD-OCT, in healthy children in a population-based study; second, using these data, to examine repeatability, reproducibility and the interocular difference.

Methods

One-hundred and ten eyes from 57 children aged 6–15 born at term, were examined. Best-corrected visual acuity and refraction were assessed. Both eyes were examined and the interocular difference was calculated. Repeatability was calculated by one examiner performing three assessments. Thereafter, a second examiner repeated the assessments to calculate reproducibility.

Results

Mean RNFL thickness was 99.2 (SD 8.8) μm, mean disc area 1.89 (SD 0.37) mm² and mean rim area 1.52 (SD 0.26) mm². No significant correlations with age, gender or refraction were found. Repeatability and reproducibility were good overall. There was interocular symmetry between the eyes.

Conclusions

Normal values for optic nerve head and RNFL thickness assessed with Cirrus SD-OCT were gathered to obtain a normal material in children. High repeatability and reproducibility indicated reliability of assessments performed by different examiners on different occasions. Overall, good correlation between right and left eyes was found.

Interocular anatomical and visual functional differences in pediatric patients with unilateral cataracts

Background

Congenital cataracts are often complicated by anterior segment dysgenesis. This study aims to compare bilateral anterior segment parameters, macular thickness, and best-corrected visual acuity (BCVA) in pediatric cataract patients at 3 months after unilateral cataract extraction with intraocular lens implantation.

Methods

Fifty-three pediatric patients with uncomplicated unilateral total cataracts were included. At 3 months post-surgery, bilateral corneal thickness at the thinnest location (CTTL), anterior chamber depth (ACD), and anterior chamber volume (ACV) were measured using Pentacam. Central macular thickness (CMT) was evaluated using spectral-domain optical coherence tomography. BCVA was measured by experienced optometrists concurrently. Descriptive statistics and bivariate corrections were performed to analyze the interocular differences in bilateral anatomic parameters and their relationships with BCVA.

Results

For all 53 included patients (mean age 5.2 ± 2.3 years), the median BCVA was 10/40 in the operated eyes and 40/40 in the contralateral eyes, which indicates a significant interocular difference. BCVA values in the contralateral eyes were significantly correlated with patient age at surgery, but this result differed for BCVA in the operated eyes. The Pentacam analysis revealed no significant interocular differences in bilateral CTTL and ACV, but significant differences were found for ACD.

Conclusions

At 3 months after surgery, unilateral pediatric cataract patients exhibited no significant interocular differences in identified anatomical parameters (except for ACD), and these parameters were not significantly correlated with BCVA in bilateral eyes. Therefore, amblyopia, but not anatomical factors, might be the main cause of interocular visual functional differences in our study population.

Trial registration

ClinicalTrial.gov, NCT02765230, 05/05/2016, retrospectively registered.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-016-0371-5) contains supplementary material, which is available to authorized users.

Discriminating anisometropic amblyopia from myopia based on interocular inhibition

Amblyopia screening during childhood is critical for early detection and successful treatment. In the current study, we develop and evaluate a screening method that exploits the imbalanced interocular inhibition between amblyopic and fellow eyes. In nineteen subjects with anisometropic amblyopia and twenty-two age-matched subjects with myopia, we measured the area under the contrast sensitivity functions (AUCSFs) in eight monocular conditions defined by the tested eye (left, right), patching of the untested eye (translucent, opaque), and refractive status (corrected, uncorrected). For each tested eye, we defined the inhibition index as the ratio between the AUCSF values obtained in the translucent and opaque patching conditions of the untested eye. To evaluate the screening potential of the inhibition index, we compared results from patients with amblyopia and myopia. With and without optical correction, the index was significantly lower in the amblyopic eye than in the fellow eye of the amblyopic subjects and both eyes of the myopic subjects. No significant difference was found among the two eyes of the myopic subjects and the fellow eyes of the amblyopic subjects. With the inhibition index as the predictor, a logistic regression model successfully discriminated amblyopic eyes from myopic eyes with 100% accuracy in the uncorrected condition. In the corrected condition, with the inhibition index and interocular visual acuity difference as predictors, amblyopic eyes were likewise discriminated from myopic eyes with 100% accuracy. This pattern of CSF changes, caused by the different patching modes of the untested eye, provides a potential CSF signature to discriminate anisometropic amblyopia from myopia.