Contrast sensitivity of amblyopic eyes in children with myopic anisometropia

Comparison of contrast sensitivity among strabismic and anisometropic amblyopes and its association with disease-related parameters

PURPOSE

To evaluate and contrast the contrast sensitivity defects present in strabismic and anisometropic amblyopes. And to find out the association of contrast deterioration with the visual acuity of the amblyopic eye, the magnitude of strabismus, and the amount of anisometropia in both groups.

METHODS

This cross-sectional study was carried out in the orthoptics unit of a tertiary eye care facility between October 2021 and December 2021. There were 45 patients altogether. In the first phase, the patient's history and ocular examination data were recorded after informed consent. The Pelli-Robson chart was used to measure contrast sensitivity. In the second phase, results were interpreted using the SPSS (Statistical Package for the Social Sciences) version 26.0.

RESULTS

Strabismic amblyopes were 24 and anisometropic amblyopes were 21. A significant positive association existed between both groups' contrast sensitivity and visual acuity (P = 0.000). A moderately negative correlation between contrast and anisometropia was statistically significant (P = 0.025) in anisometropic amblyopes. However, no association (P > 0.050) existed between the contrast and magnitude of strabismus in any group.

CONCLUSION

The study concluded that contrast sensitivity decreases in both groups, whereas anisometropic amblyopes have poorer contrast than strabismic amblyopes. Excessively decreased contrast sensitivity among anisometropic amblyopes was solely because of the worst amblyopia in this group, whereas the magnitude of strabismus does not affect contrast sensitivity.

Characteristics and Related Parameters of Quick Contrast Sensitivity Function in Chinese Ametropia Children

PURPOSE

To investigate the characteristics of quick contrast sensitivity function (qCSF) and its related parameters in Chinese ametropia children.

METHODS

This case series study enrolled 106 eyes of 53 children (male/female=29/24, age: 9.04±2.06 years). Examinations included manifest refraction, axial length, corneal curvature, and monocular and binocular qCSF readings without refractive correction (area under log CSF [AULCSF], CSF acuity, and contrast sensitivity [CS] at 1.0 to 18.0 cpd). The subjects were divided into groups according to age and refractive parameters for analysis.

RESULTS

The mean spherical equivalent (SE), AULCSF, and CSF acuity of the test eyes were -0.94±1.53 D, 0.44±0.33, and 8.50±5.97 cpd, respectively. In the monocular qCSF comparison, the refraction sphere (RS) was the major factor correlated with qCSF readings (B=0.186, P =0.009 for AULCSF; B=0.543, P =0.019 for CSF acuity; generalized linear model). The three groups stratified by RS/SE (<-1.00D, -1.00D to 0D, and >0D) showed significant differences in CS at medium spatial frequencies (3.0 and 6.0 cpd; all P <0.05). In the low RS/SE group (within -1 to 0 D), the CS at 12.0 cpd was significantly lower than that in the hyperopia group (all P <0.05). Binocular qCSF readings were significantly correlated with those of the eyes with lower RS (all P <0.05).

CONCLUSION

RS and SE are the major contributing factors of qCSF without refractive correction in children. The CS at medium spatial frequencies decrease significantly as the RS/SE increase. In low myopia children, the CS at medium and high spatial frequencies are significantly decreased, providing practical value in visual function screening in children.

Analysis of Changes in High-order Aberration and Contrast Sensitivity After Epiblepharon Surgery

PURPOSE

To investigate changes in corneal anterior high-order aberration (HOA) and contrast sensitivity (CS) before and after epiblepharon surgery.

METHODS

A retrospective observational analysis of the degree of corneal erosion, HOAs and CS was conducted in the OD and OS, respectively, before and after epiblepharon surgery. The correlations between corneal erosion, HOAs, and CS were analyzed.

RESULTS

Forty-nine patients were included in the study. Among the anterior HOAs, total HOA, coma, and trefoil showed significant improvement after surgery ( P = 0.003, P = 0.009, and P = 0.018, respectively). In the CS test, there was a significant improvement in CS after surgery at 1.1 cycles per degree (cpd) under photopic conditions, regardless of glare. Preoperative correlation analysis between HOAs and corneal erosion showed a significant positive correlation with total HOA ( P = 0.001) and coma ( P = 0.001). Preoperative correlation analysis between CS and corneal erosion showed a significant negative correlation at 1.1 cpd with glare under photopic conditions ( P = 0.049). A negative correlation was also observed between CS under mesopic and photopic conditions and total HOA both before and after surgery.

CONCLUSION

Significant improvement in corneal anterior HOAs and CS at 1.1 cpd under photopic conditions was observed after epiblepharon surgery. Total HOA of anterior cornea showed a negative correlation with CS. A decrease in HOAs and recovery of corneal erosion after epiblepharon surgery will help improve CS.

Binocular contrast sensitivity in patients with intermittent exotropia in relation to angle of strabismus and level of compensation

Intermittent exotropia (IXT) causes photophobia, and photophobia has been studied by measurement of contrast sensitivity (CS). CS was reduced in children with IXT. We compared binocular CS (BCS) in patients with IXT and normal subjects in relation to the angle of strabismus and control of IXT. This case-control study was performed on 40 patients with IXT and 40 normal subjects who were examined with the CSV1000 CS device in mesopic (3 cd/m2) and photopic (85 cd/m2) conditions with and without a glare stimulus at 3, 6, 12, and 18 cycle/degree (cpd) spatial frequencies. The angle of strabismus and near stereoacuity were also measured. The patient's IXT compensation was graded based on the office control scale. The mean age for IXT and normal participants were 12.30 ± 0.60 (range, 6-18) and 11.00 ± 0.78 (range, 6-18) years, respectively (P = .34). The IXT patients had lower binocular CS than controls at all spatial frequencies (P < .001). The largest decrease in CS occurred at 6 cpd spatial frequency under mesopic condition (1.61 ± 0.07 vs 1.38 ± 0.15, P < .001) and photopic condition with glare (2.03 ± 0.06 vs 1.77 ± 0.13, P < .001). Patients with better control scores had higher levels of BCS; also, the score of BCS showed a significant decrease in patients with a deviation of 25 prism diopter or more, compared to those with less deviation. BCS correlated at 3 and 6 cpd with near stereoacuity (r = -0.652, P < .001 and r = -0.613, P < .001). Binocular CS in patients with IXT correlates with the angle of strabismus and level of compensation.

Changes in contrast sensitivity after surgery for intermittent exotropia

To determine whether intermittent exotropia (IXT) surgery affects contrast sensitivity (CS), this retrospective study evaluated the changes in monocular and binocular CS and the binocular summation ratio (BSR) quantified as the ratio between the values of the binocular and the better monocular CS score (BSR = binocular CS score/better monocular CS score) after surgery for IXT. The subjects were patients who had undergone IXT-correcting surgery with a postoperative follow-up of > 3 months and had pre- and postoperative records of Mars CS test scores. In total, 64 patients (128 eyes) were evaluated. Both the binocular and monocular CS scores of the operated eyes were significantly worse on postoperative 1 day than the preoperative scores, but they were recovered after 1 week. The monocular CS scores of the operated eyes were significantly worse than those of the non-operated eyes until 1 week. There was no significant difference in monocular CS scores between the one-muscle and two-muscle surgeries and in binocular CS scores between the successful alignment and overcorrection groups even on the first day after surgery. The mean BSR was significantly decreased until postoperative month 1, however, recovered to preoperative levels after month 3. In conclusion, IXT-correcting surgery may temporarily worsen the CS, but it is recovered to preoperative levels. Thus, changes in CS in the immediate postoperative period after strabismus surgery should not be of concern.

Examination of Macular Retina and Choroidal Thickness in High Myopic Amblyopia Using Spectral-Domain Optical Coherence Tomography

Purpose

The aim of this study was to investigate changes in the retinal and choroidal thickness between high myopic amblyopia (HMA), low myopia (LM), moderate myopia (MM), high myopia (HM), and normal group (NG) using a spectral-domain optical coherence tomography (SD-OCT).

Materials and Methods

A total of 75 Chinese children (128 eyes; mean age 10.5 years) were recruited. Retinal thickness (RT) and choroidal thickness (CT) were measured at different locations including subfoveal (SF), and at 0.5 mm/1.0 mm/1.5 mm/2.0 mm/2.5 mm/3.0 mm to the fovea in superior, nasal, inferior, and temporal sectors using enhanced depth imaging (EDI) system of SD-OCT. Axial length (AL), best-corrected visual acuity (BCVA), and refraction errors were also collected.

Results

No significant differences were found in subfoveal retinal thickness (SFRT). Moreover, a significantly thinner subfoveal choroidal thickness (SFCT) was found in HMA compared to NG, LM, and MM, but not compared to HM. RT at 0.5 mm to fovea, HMA was significantly thinner compared to LM and MM in the three sectors (superior, inferior, and temporal). Nevertheless, no significant differences were found compared to NG and HM. CT at 0.5 mm to fovea, HMA was the significantly thinnest in all four sectors compared to NG, LM, and MM. RT at 1.0 mm/1.5 mm/2.0 mm/2.5 mm/3.0 mm to fovea, HMA was thinner compared to NG, LM, and MM. CT at 1.0 mm/1.5 mm/2.0 mm/2.5 mm/3.0 mm to fovea, HMA was thinner compared to NG, LM, and MM. At the superior and inferior sectors, HMA showed to be statistically thinner compared with HM. Moreover, SFCT in the HMA, HM, and NG were negatively correlated with AL.

Conclusions

Thinner retina and choroidal tissue appear to be related to HMA, and thus can be used as useful parameters for discovering the underlying mechanisms of the disease.

Global Tendency and Frontiers of Research on Myopia From 1900 to 2020: A Bibliometrics Analysis

Background:

Myopia is one of the most common causes of vision impairment in children and adults and has become a public health priority with its growing prevalence worldwide. This study aims to identify and evaluate the global trends in myopia research of the past century and visualize the frontiers using bibliometric analysis.

Methods

The literature search was conducted on the Web of Science for myopia studies published between 1900 and 2020. Retrieved publications were analyzed in-depth by the annual publication number, prolific countries and institutions, core author and journal, and the number of citations through descriptive statistics. Collaboration networks and keywords burst were visualized by VOSviewer and CiteSpace. Myopia citation network was visualized using CitNetExplorer.

Results

In total, 11,172 publications on myopia were retrieved from 1900 to 2020, with most published by the United States. Saw SM, from the National University of Singapore, contributed the most publications and citations. Investigative Ophthalmology &amp; Visual Science was the journal with highest number of citations. Journal of Cataract and Refractive Surgery with the maximum number of publications. The top 10 cited papers mainly focused on the epidemiology of myopia. Previous research emphasized myopia-associated experimental animal models, while recent keywords include “SMILE” and “myopia control” with the stronger burst, indicating a shift of concern from etiology to therapy and coincided with the global increment of incidence. Document citation network was clustered into six groups: “prevalence and risk factors of myopia,” “surgical control of myopia,” “pathogenesis of myopia,” “optical interventions of myopia,” “myopia and glaucoma,” and “pathological myopia.”

Conclusions

Bibliometrics analysis in this study could help scholars comprehend global trends of myopia research frontiers better. Hundred years of myopia research were clustered into six groups, among which “prevalence and risk factors of myopia” and “surgical control of myopia” were the largest groups. With the increasing prevalence of myopia, interventions of myopia control are a potential research hotspot and pressing public health issue.

Repeatability of an automated ETDRS contrast threshold measurement

This technical report presents the repeatability of an automated Early Treatment Diabetic Retinopathy Study (ETDRS) contrast threshold (ETDRS-CT) test in participants (N = 40) with normal vision as well as in subjects with reduced visual acuity. The automated ETDRS-CT test showed good test-retest repeatability between the two administrations in both normal and reduced vision participants. Measurement at the retest yielded 0.05 log higher contrast sensitivity than at the first measurement, which might be due to a learning effect among participants.

Validation of an Automated Early Treatment Diabetic Retinopathy Study Low-contrast Letter Acuity Test

SIGNIFICANCE

Automated low-contrast letter acuity (LCLA) has several advantages: consistent luminance, reduced chance of individuals memorizing test letters, and convenient and accurate visual acuity reporting functions. Although automated LCLA might report slightly worse acuity than Sloan LCLA chart, considering its advantages, it may be a viable alternative to Sloan LCLA chart in clinical practice and research.

PURPOSE

The purpose of this study was to determine the repeatability of an automated LCLA measurement and its agreement with the Sloan LCLA chart test in normal participants and reduced-vision participants.

METHODS

Adult participants (n = 49) were measured with both automated Early Treatment Diabetic Retinopathy Study and Sloan LCLA tests, including normal and reduced-vision groups. Low-contrast letter acuity at two contrast levels (2.5 and 10%) was measured at 3 m in a random sequence with both LCLA tests. To test repeatability, participants were retested 1 week later. Repeatability of the two tests between two visits and agreement between automated and Sloan LCLA tests were evaluated using 95% limits of agreement.

RESULTS

In terms of the 95% limits of agreement, the repeatability of both tests was as follows: automated LCLA at 2.5%, ±0.26; automated LCLA at 10%, ±0.22; Sloan LCLA at 2.5%, ±0.23, and Sloan LCLA at 10%, ±0.16. The agreement of the two tests was as follows: ±0.19 at 2.5% and ±0.24 at 10%. The automated LCLA at 2.5 and 10% levels was generally reported one-half to one logMAR line lower than Sloan LCLA (mean differences, -0.04 at 2.5% and -0.13 at 10%; paired t test, P < .05).

CONCLUSIONS

The automated LCLA test shows fairly good test-retest repeatability at both 2.5 and 10% contrast levels. The agreement between the automated and the Sloan low-contrast letter acuity tests was comparable with test-retest agreement. Although the automated LCLA test reports slightly worse acuity than the Sloan LCLA test, it could be an appropriate alternative to the Sloan LCLA test.

Stimuli Characteristics and Psychophysical Requirements for Visual Training in Amblyopia: A Narrative Review

Active vision therapy using perceptual learning and/or dichoptic or binocular environments has shown its potential effectiveness in amblyopia, but some doubts remain about the type of stimuli and the mode and sequence of presentation that should be used. A search was performed in PubMed, obtaining 143 articles with information related to the stimuli used in amblyopia rehabilitation, as well as to the neural mechanisms implied in such therapeutic process. Visual deficits in amblyopia and their neural mechanisms associated are revised, including visual acuity loss, contrast sensitivity reduction and stereopsis impairment. Likewise, the most appropriate stimuli according to the literature that should be used for an efficient rehabilitation of the amblyopic eye are described in detail, including optotypes, Gabor’s patches, random-dot stimuli and Vernier’s stimuli. Finally, the properties of these stimuli that can be modified during the visual training are discussed, as well as the psychophysical method of their presentation and the type of environment used (perceptual learning, dichoptic stimulation or virtual reality). Vision therapy using all these revised concepts can be an effective option for treating amblyopia or accelerating the treatment period when combining with patching. It is essential to adapt the stimuli to the patient’s individual features in both monocular and binocular training.

Factors Affecting Contrast Sensitivity in Intermittent Exotropia

PURPOSE

To determine whether contrast sensitivity (CS) can represent photophobia in intermittent exotropia (IXT) by comparing the CS test with and without glare stimulus, and to analyze the factors of IXT affecting CS.

METHODS

We retrospectively reviewed the medical records of 107 patients with basic-type IXT. We compared CS under mesopic and photopic conditions, with and without glare. We compared the difference in CS before and after glare (ΔCS) between mesopic and photopic conditions, and compared CS with glare between patients with and without photophobia. The correlations between the clinical features of IXT and CS were analyzed.

RESULTS

There was no significant reduction in CS at all spatial frequencies by glare stimulus. ΔCS was greater at high spatial frequencies under photopic conditions than under mesopic conditions. The group with subjective photophobia showed lower CS at 10.2 cpd under mesopic conditions with glare. CS showed a negative correlation with stereopsis under both mesopic and photopic conditions, and a positive correlation with fusional ability at low and intermediate spatial frequencies under mesopic conditions. ΔCS was smaller at intermediate spatial frequencies with better fusional ability, greater at high spatial frequencies with photophobia, and greater at intermediate spatial frequencies with a higher frequency of exotropia.

CONCLUSIONS

The CS test could not represent photophobia in IXT. However, CS tended to decrease with glare stimulus, and CS under mesopic conditions with glare was worse when accompanied by photophobia. Moreover, a poorer degree of stereopsis was associated with lower CS, and better fusional ability was associated with higher CS under mesopic conditions. Therefore, the CS test can be considered helpful in evaluating sensory function in IXT.

Comparison of contrast sensitivity based on the surgical results for intermittent exotropia

AIM

To compare contrast sensitivity (CS) based on the surgical results for intermittent exotropia (IXT) and to examine the relationship between CS and photophobia.

METHODS

Medical records of the patients who underwent bilateral lateral rectus muscle recession for IXT between 4 and 12 years old were reviewed retrospectively. They were categorized based on the surgical results; successful correction group (n=36) and overcorrection group (esotropia ≥10 PD at 3mo postoperatively, n=18). Using CGT-2000 test for CS was performed binocularly, and subjective reports of photophobia was investigated preoperatively and at 3mo postoperatively. Objective photophobia was defined as a significant decrease in CS in the presence of glare.

RESULTS

Preoperatively, there was no difference in CS between the groups. Postoperatively, under mesopic conditions, significant improvement of CS was observed at 6.3°, 4°, and 2.5° in the successful correction group and at 6.3° and 4° in the overcorrection group, regardless of glare. Under photopic conditions, at all visual angles except 0.64°, improvement in CS was noted in both groups while CS worsened significantly at 0.64° in the overcorrection group postoperatively. At all visual angles under photopic conditions postoperatively, regardless of glare, CS in the overcorrected group was significantly worse than that in the successful correction group, and CS was significantly decreased by addition of glare in both groups. All patients except one (96.4%) in the successful correction group and 8 patients (61.5%) in overcorrection group showed improvement of photophobia postoperatively, which correlated with CS under photopic conditions (P=0.001, 0.03).

CONCLUSION

After surgery for IXT, CS under photopic conditions improve at all visual angles except 0.64°, while CS is significantly worse in the overcorrection group postoperatively at 0.64°. Subjective photophobia have significant correlation with CS under photopic conditions, and may be used as an objective indicator of photophobia.