Factors predicting regression of visual acuity following successful treatment of anisometropic amblyopia

Longitudinal evaluation of macular vascular density alterations in unilateral amblyopic children undergoing therapy: An optical coherence tomographic angiography study

Importance

Understanding the pathophysiology of the macula in amblyopic eyes is an active research area.

Objective

To correlate macular retinal vascular density changes with best-corrected visual acuity changes following occlusion therapy for amblyopia in children.

Design

A prospective cohort study of children visiting the Pediatric Ophthalmology Division of our institution between January 2020 and January 2022 was conducted.

Setting

A specialist eye hospital in Saudi Arabia.

Participants

Thirty children with unilateral amblyopia.

Exposure

Occlusion therapy for amblyopia.Main Outcome and Measures: Best corrected visual acuity (logMAR) before and at each of the four optical coherence tomographic angiographies was compared in amblyopic and fellow eyes. The effect of pretreatment determinants on the correlation between best-corrected visual acuity and retinal vascular density changes was reviewed.

Results

In this cohort of 30 amblyopic and 30 fellow eyes from 30 children (mean age 8.7 ± 1.4 years; male: female 18:12. The best-corrected visual acuity improved from a median of 0.6 (interquartile range 0.5; 1.1) pretreatment to a median of 0.4 (interquartile range 0.2; 0.6) posttreatment in amblyopic eyes, and from a median of 0.1 to 0.05 in the fellow eyes. The total percentage change in retinal vascular density in the amblyopic eye was significantly higher than that in the fellow eye (Z = -1.92, P = 0.05). The change in best-corrected visual acuity in the amblyopic eye after a median of 98 months (interquartile range, 69-126 months) of intervention was significantly correlated with the refraction-adjusted change in retinal vascular density (B = -0.03, 95 % confidence interval -0.04, -0.02, P < 0.001) and was influenced by strabismus (B = -0.46, 95 % confidence interval -0.59, -0.34, P < 0.001), type of amblyopia (B = 0.24, 95 % confidence interval 0.12, 0.36, P < 0.001), duration of occlusion (B = -0.43, 95 % confidence interval -0.65, -0.22, P < 0.001), and occlusion compliance (B = 0.24, 95 % confidence interval 0.11, 0.36, P < 0.001).

Conclusions

and Relevance: The RVD in amblyopic eyes in the first six months of therapy was significantly lower than that in fellow eyes, but not in subsequent assessments.

Novel Quantitative Contrast Sensitivity Function Enhances the Prediction of Treatment Outcome and Recurrence in Amblyopia

Purpose

Although effective amblyopia treatments are available, treatment outcome is unpredictable, and the condition recurs in up to 25% of the patients. We aimed to evaluate whether a large-scale quantitative contrast sensitivity function (CSF) data source, coupled with machine learning (ML) algorithms, can predict amblyopia treatment response and recurrence in individuals.

Methods

Visual function measures from traditional chart vision acuity (VA) and novel CSF assessments were used as the main predictive variables in the models. Information from 58 potential predictors was extracted to predict treatment response and recurrence. Six ML methods were applied to construct models. The SHapley Additive exPlanations was used to explain the predictions.

Results

A total of 2559 consecutive records of 643 patients with amblyopia were eligible for modeling. Combining variables from VA and CSF assessments gave the highest accuracy for treatment response prediction, with the area under the receiver operating characteristic curve (AUC) of 0.863 and 0.815 for outcome predictions after 3 and 6 months, respectively. Variables from the VA assessment alone predicted the treatment response, with AUC values of 0.723 and 0.675 after 3 and 6 months, respectively. Variables from the CSF assessment gave rise to an AUC of 0.909 for recurrence prediction compared to 0.539 for VA assessment alone, and adding VA variables did not improve predictive performance. The interocular differences in CSF features are significant contributors to recurrence risk.

Conclusions

Our models showed CSF data could enhance treatment response prediction and accurately predict amblyopia recurrence, which has the potential to guide amblyopia management by enabling patient-tailored decision making.

Associations between the cause of amblyopia and pre-treatment contrast sensitivity, stereoacuity, fixation, and nystagmus

Purpose

To explore the association between the cause of amblyopia and pre-treatment contrast sensitivity, stereoacuity, fixation and nystagmus.

Design

Retrospective cohort study.

Methods

A retrospective review was conducted for 3408 patients with amblyopia who had not yet started amblyopia treatment utilizing a large amblyopia patient database maintained at Zhongshan Ophthalmic Centre. Six amblyogenic factor subtypes were identified: anisometropia, isoametropia, strabismus, anisometropia and strabismus, monocular visual deprivation, and binocular visual deprivation amblyopia. Monocular best corrected visual acuity (BCVA), the contrast sensitivity function (CSF), fixation, and stereopsis were compared between the subtypes before and after propensity score matching (PSM) for age and sex.

Results

The two deprivation groups had poorer BCVA and CSF than the other groups. There were no systematic differences in CSF between the non-deprivation groups. Nystagmus was more common in the bilateral amblyopia groups compared to the monocular amblyopia groups. Eccentric fixation was uncommon with the exception of the anisometropia and strabismus group which had an eccentric fixation rate of 20%. Distance stereoacuity measured without monocular cues was absent for almost all patients. The results were consistent when analyzed using PSM.

Conclusion

Visual deprivation causes more severe amblyopia than other amblyogenic factors. For non-deprivation amblyopia subtypes, individual differences such as variation in the severity of the amblyogenic factor might be more important in determining pre-treatment vision than whether amblyopia was caused by refractive error, strabismus or both.

Perceptual Learning Based on the Lateral Masking Paradigm in Anisometropic Amblyopia With or Without a Patching History

Purpose

Perceptual learning (PL) has shown promising performance in restoring visual function in adolescent amblyopes. We retrospectively compared the effect of a well-accepted PL paradigm on patients with anisometropic amblyopia with or without a patching therapy history (patching therapy [PT] group versus no patching therapy [NPT] group).

Methods

Eighteen PT and 13 NPT patients with anisometropic amblyopia underwent monocular PL for 3 months. During training, patients practiced a Gabor detection task following the lateral masking paradigm by applying a temporal two-alternative forced choice procedure with the amblyopic eye. Monocular contrast sensitivity functions (CSF), visual acuity, interocular differences in visual function metrics, and stereoacuity were compared before and after training.

Results

PL improved the visual acuity of the amblyopia eyes by 0.5 lines on average in the PT group and 1.5 lines in the NPT group. A significant reduction in the interocular difference in visual acuity was observed in the NPT group (P < 0.01) but not in the PT group (P = 0.05). Regarding CSF metrics, the area under the log CSF and cutoff in the amblyopic eyes of the NPT groups increased after training (P < 0.05). In addition, the interocular differences of the CSF metrics (P < 0.05) in the NPT group were significantly reduced. However, in the PT group, all the CSF metrics were unchanged after training. A total of 27 of 31 patients in both groups had no measurable stereopsis pretraining, and recovery after training was not significant.

Conclusions

PL based on a lateral masking training paradigm improved visual function in anisometropic amblyopia. Patients without a patching history achieved greater benefits.

Translational Relevance

PL based on a lateral masking training paradigm could be a new treatment for amblyopia.

Human deprivation amblyopia: treatment insights from animal models

Amblyopia is a common visual impairment that develops during the early years of postnatal life. It emerges as a sequela to eye misalignment, an imbalanced refractive state, or obstruction to form vision. All of these conditions prevent normal vision and derail the typical development of neural connections within the visual system. Among the subtypes of amblyopia, the most debilitating and recalcitrant to treatment is deprivation amblyopia. Nevertheless, human studies focused on advancing the standard of care for amblyopia have largely avoided recruitment of patients with this rare but severe impairment subtype. In this review, we delineate characteristics of deprivation amblyopia and underscore the critical need for new and more effective therapy. Animal models offer a unique opportunity to address this unmet need by enabling the development of unconventional and potent amblyopia therapies that cannot be pioneered in humans. Insights derived from studies using animal models are discussed as potential therapeutic innovations for the remediation of deprivation amblyopia. Retinal inactivation is highlighted as an emerging therapy that exhibits efficacy against the effects of monocular deprivation at ages when conventional therapy is ineffective, and recovery occurs without apparent detriment to the treated eye.

Impact of COVID-19 pandemic control measures on amblyopia treatment: a retrospective study of records from a tertiary eye hospital in China

OBJECTIVES

Amblyopia is the most common cause of unilateral visual impairment in children and requires long-term treatment. This study aimed to quantify the impact of pandemic control measures on amblyopia management.

DESIGN AND SETTING

This was a retrospective cohort study of data from a large amblyopia management database at a major tertiary eye care centre in China.

PARTICIPANTS

Outpatients with amblyopia who visited the hospital from 1 June 2019, through 28 February 2022.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the number of first and follow-up in-person visits to the hospital for amblyopia treatment. Secondary outcomes included the time interval between consecutive visits and improvement of vision (visual acuity, contrast sensitivity and stereopsis). Patient records were grouped into prepandemic and during pandemic periods.

RESULTS

A total of 10 060 face-to-face visits for 5361 patients (median age 6.7 years, IQR 5.4, 8.9) that spanned two lockdown periods were included in the analysis, of which 28% were follow-up visits. Pandemic control measures caused a sharp decline in the number of outpatient visits (3% and 30% of prepandemic levels in the months directly after the start of the first (2020) and second (2021) periods of pandemic control measures, respectively). However, these drops were followed by pronounced rebounds in visits that exceeded prepandemic levels by 51.1% and 108.5%, respectively. The interval between consecutive visits increased significantly during the pandemic from a median (IQR) of 120 (112, 127) days in 2019 to 197 (179, 224) in 2020 (p<0.001) and 189 (182, 221) in 2021 (p<0.001). There were no significant differences in the improvement of visual function or treatment compliance between the prepandemic and postpandemic groups.

CONCLUSIONS

The number of amblyopia patient hospital visits spiked well above prepandemic levels following lockdown periods. This pattern of patient behaviour can inform planning for amblyopia treatment services during and after public health-related disruptions.

Investigation of the efficacy and safety of retinal inactivation as a treatment for amblyopia in cats

Introduction

Deprivation of normal vision early in postnatal development elicits modifications of neural circuitry within the primary visual pathway that can cause a severe and intractable vision impairment (amblyopia). In cats, amblyopia is often modeled with monocular deprivation (MD), a procedure that involves temporarily closing the lids of one eye. Following long-term MD, brief inactivation of the dominant eye's retina can promote recovery from the anatomical and physiological effects of MD. In consideration of retinal inactivation as a viable treatment for amblyopia it is imperative to compare its efficacy against conventional therapy, as well as assess the safety of its administration.

Methods

In the current study we compared the respective efficacies of retinal inactivation and occlusion of the dominant eye (reverse occlusion) to elicit physiological recovery from a prior long-term MD in cats. Because deprivation of form vision has been associated with development of myopia, we also examined whether ocular axial length or refractive error were altered by a period of retinal inactivation.

Results

The results of this study demonstrate that after a period of MD, inactivation of the dominant eye for up to 10 days elicited significant recovery of visually-evoked potentials that was superior to the recovery measured after a comparable duration of reverse occlusion. After monocular retinal inactivation, measurements of ocular axial length and refractive error were not significantly altered from their pre-inactivation values. The rate of body weight gain also was not changed during the period of inactivation, indicating that general well-being was not affected.

Discussion

These results provide evidence that inactivation of the dominant eye after a period of amblyogenic rearing promotes better recovery than eye occlusion, and this recovery was achieved without development of form-deprivation myopia.

Evaluation of Aniseikonia in Patients with Successfully Treated Anisometropic Amblyopia Using Spatial Aniseikonia Test

Anisometropic amblyopia is decreased visual acuity in one eye, and treatment consists of wearing complete corrective spectacles. Aniseikonia occurs with complete correction of anisometropia using spectacles. Aniseikonia has been ignored when treating pediatric anisometropic amblyopia because of the prevailing belief that anisometropic symptoms are suppressed by adaptation. However, the conventional direct comparison method for evaluating aniseikonia significantly underestimates the degree of aniseikonia. This study investigated whether the adaptation occurs due to long-term anisometropic amblyopia treatment in patients who have had successful amblyopia treatment using a spatial aniseikonia test with high accuracy and repeatability compared with the conventional direct comparison method. The amount of aniseikonia was not significantly different between the patients with successful amblyopia treatment and individuals with anisometropia without a history of amblyopia. In both groups, the aniseikonia per 1.00 D of anisometropia and the aniseikonia per 1.00 mm of aniso-axial length were comparable. The repeatability of the amount of aniseikonia using the spatial aniseikonia test did not differ significantly between the two groups, indicating a high degree of agreement. These findings suggest that aniseikonia is not adapted to amblyopia treatment and that aniseikonia increases as the difference between spherical equivalent and axial length increases.