Analyses of eye movement parameters in children with anisometropic amblyopia.

OBJECTIVE: To investigate the characteristics of eye movement in children with anisometropic amblyopia, and to compare those characteristics with eye movement in a control group. METHODS: 31 children in the anisometropic amblyopia group (31 amblyopic eyes in group A, 31 contralateral eyes in group B) and 24 children in the control group (48 eyes in group C). Group A was subdivided into groups Aa (severe amblyopia) and Ab (mild-moderate amblyopia). The overall age range was 6-12 years (mean, 7.83 ± 1.79 years). All children underwent ophthalmic examinations; eye movement parameters including saccade latency and amplitude were evaluated using an Eyelink1000 eye tracker. Data Viewer and MATLAB software were used for data analysis. RESULTS: Mean and maximum saccade latencies, as well as mean and maximum saccade amplitudes, were significantly greater in group A than in groups B and C before and after treatment (P < 0.05). Mean and maximum saccade latencies were significantly different among groups Aa, Ab, and C (P < 0.05). Pupil trajectories in two detection modes suggested that binocular fixation was better than monocular fixation. CONCLUSIONS: Eye movement parameters significantly differed between contralateral normal eyes and control eyes. Clinical evaluation of children with anisometropic amblyopia should not focus only on static visual acuity, but also on the assessment of eye movement.

Characteristics of peripheral refractive errors in eyes of patients with non-amblyopic myopic anisometropia.

BACKGROUND: This study aims to investigate relative peripheral refractive (RPR) characteristics in children with non-amblyopic myopic anisometropia and explore potential associations between relative peripheral refractive errors (RPRE) and myopia. METHODS: Relative peripheral refractive errors were assessed in 64 children diagnosed with non-amblyopic myopic anisometropia utilizing multispectral refraction topography (MRT). Two eyes of each patient were divided into into the more myopia eyes group (ME) and the fellow eyes group (FE). Evaluated parameters encompassed total defocus values (TRDV), defocus values at eccentricities spanning 0 to 15 degrees (RDV-15), 0 to 30 degrees (RDV-30), 0 to 45 degrees (RDV-45), as well as superior (RDV-S), inferior (RDV-I), temporal (RDV-T), and nasal (RDV-N) positions. RESULTS: The study revealed a noteworthy contrast in TRDV values between Group ME (0.52 ± 0.36) and Group FE (0.17 ± 0.41), with a substantial significance (P < 0.0001). While no significant RDV-15 difference emerged between Group ME (0.01 ± 0.05) and Group FE (-0.01 ± 0.07) (P > 0.05), a meaningful RDV-30 difference existed between Group ME (0.11 ± 0.14) and Group FE (0.03 ± 0.19) (P = 0.0017). A significant discrepancy in RDV-45 was also observed between Group ME (0.39 ± 0.29) and Group FE (0.13 ± 0.34) (P < 0.001). Notably, RDV-I and RDV-T positions demonstrated marked differences between Group ME and Group FE (P < 0.0001), whereas no significant disparity was noted in RDV-S and RDV-N positions (P > 0.05). CONCLUSION: Eyes exhibiting greater myopia manifested more hyperopic peripheral defocus in the context of anisometropia. MRT as a novel ophthalmic evaluation technique, holds promising potential for broader clinical applications in the future.

Association of choroidal thickness and blood flow features with asymmetric axial lengths in children with unilateral myopic anisometropia.

BACKGROUND: Considering that changes in the choroidal thickness are closely related to ocular growth, we studied the choroidal thickness (CT) and the blood flow features in children with unilateral myopic anisometropia (UMA) as well as investigating the relationship between choroidal changes and myopia. METHODS: Subjective refractive, axial length (AL), and biometric parameters were measured in 98 UMA children (age: 8-15 years). CT and choroidal blood-flow features, including the choroidal vessel volume (CVV), choroidal vascularity index (CVI), and choriocapillaris perfusion area (CCPA), were measured through swept-source optical coherence tomography angiography. The macular region was categorized into four concentric circles of diameters 0-1 mm (central fovea), 1-3 mm (parafovea), 3-6 mm (perifovea), and 6-9 mm (extended), and further categorized into superior (S), inferior (I), temporal (T), and nasal (N) quadrants. RESULTS: The aforementioned four regions of myopic eyes displayed significantly lower CT, CVV, and CVI than those of non-myopic eyes. CCPA changes differed across different regions of both the eyes (parts of N and T quadrants). There was an inverse association between CT and the interocular AL difference (central and other regions S, T quadrant). No correlation was noted between CVV and CVI with interocular AL difference. CT and CVV were positively correlated in the 0-6-mm macular region of myopic eyes (Spearman correlation coefficient = 0.763, P < 0.001). CONCLUSIONS: In UMA children, CCT and blood flow may be related to myopia progression. A robust correlation between CT and CVV in the 0-6-mm macular region and reduced CT and diminished blood flow indicated an association with myopia.

Anisomyopia and orthokeratology for myopia control - Axial elongation and relative peripheral refraction.

PURPOSE: To investigate axial elongation (AE) and changes in relative peripheral refraction (RPR) in anisomyopic children undergoing orthokeratology (ortho-k). METHODS: Bilateral anisomyopic children, 7-12 years of age, were treated with ortho-k. Axial length (AL) and RPR, from 30° nasal (N30°) to 30° temporal (T30°), were measured at baseline and every 6 months over the study period. AE, changes in RPR and changes in the interocular AL difference were determined over time. RESULTS: Twenty-six of the 33 subjects completed the 2-year study. The AE of the higher myopic (HM) eyes (at least 1.50 D more myopia than the other eye) (0.26 ± 0.29 mm) was significantly smaller than for the less myopic (LM) eyes (0.50 ± 0.27 mm; p = 0.003), leading to a reduction in the interocular difference in AL (p = 0.001). Baseline RPR measurements in the HM eyes were relatively more hyperopic at T30°, N20° and N30° (p ≤ 0.02) and greater myopic shifts were observed at T20° (p < 0.001), T30° (p < 0.001), N20° (p = 0.02) and N30° (p = 0.01) after lens wear. After 2 years of ortho-k lens wear, temporal-nasal asymmetry increased significantly, being more myopic at the temporal locations in both eyes (p < 0.001), while AE was associated with the change in RPR at N20° (ß = 0.134, p = 0.01). The interocular difference in AE was also positively associated with the interocular difference in RPR change at N30° (ß = 0.111, p = 0.02). CONCLUSIONS: Ortho-k slowed AE in bilateral anisomyopia, with slower growth in the HM eyes leading to a reduction in interocular AL differences. After ortho-k, RPR changed from hyperopia to myopia, with greater changes induced in the HM eyes, and slower AE was associated with a more myopic shift in RPR, especially in the nasal field of both eyes.

Resting-State Functional Connectivity of the Primary Visual Cortex in Children with Anisometropia Amblyopia.

INTRODUCTION: This study aimed to explore the functional connectivity of the primary visual cortex (V1) in children with anisometropic amblyopia by using the resting-state functional connectivity analysis method and determine whether anisometropic amblyopia is associated with changes in brain function. METHODS: Functional magnetic resonance imaging (fMRI) data were obtained from 16 children with anisometropia amblyopia (CAA group) and 12 healthy children (HC group) during the resting state. The Brodmann area 17 (BA17) was used as the region of interest, and the functional connection (FC) of V1 was analyzed in both groups. A two-sample t test was used to analyze the FC value between the two groups. Pearson's correlation was used to analyze the correlation between the mean FC value in the brain function change area of the CAA group and the best corrected visual acuity (BCVA) of amblyopia. p < 0.05 was considered statistically significant. RESULTS: There were no significant differences in age and sex between the CAA and HC groups (p > 0.05). Compared to the HC group, the CAA group showed lower FC values in BA17 and the left medial frontal gyrus, as well as BA17 and the left triangle inferior frontal gyrus. Conversely, the CAA group showed higher FC values in BA17 and the left central posterior gyrus. Notably, BCVA in amblyopia did not correlate with the area of change in mean FC in the brain function of the CAA group. CONCLUSION: Resting-state fMRI-based functional connectivity analysis indicates a significant alteration in V1 of children with anisometropic amblyopia. These findings contribute additional insights into the neuropathological mechanisms underlying visual impairment in anisometropic amblyopia.

Ocular Anatomical and Functional Characteristics in Anisometropic Chinese Children.

SIGNIFICANCE: This research found that anterior and posterior biometrics differ in many aspects between fellow eyes of anisometropic children. This might shed light on the mechanisms underlying the onset and progression of anisometropia and myopia. PURPOSE: This study aimed to investigate the ocular biometric parameters, peripheral refraction, and accommodative lag of fellow eyes in anisometropic children. METHODS: Anisometropic children were recruited. Axial length (AL), vitreous chamber depth (VCD), central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), simulated K readings, central and peripheral refractive errors, and accommodative lag were measured in both eyes. The subfoveal choroidal thickness, average choroidal thickness, and choroid vessel density of the 6 × 6-mm macular area were measured by optical coherence tomography. RESULTS: Thirty-two children aged 11.1 ± 1.7 years were enrolled. The average degree of anisometropia was 2.49 ± 0.88 D. The AL, VCD, ACD, and simulated K reading values were significantly larger in the more myopic eyes, whereas the LT value was significantly smaller. Subfoveal choroidal thickness (P = .001) and average choroidal thickness (P = .02) were smaller in the more myopic eyes than in the contralateral eyes, whereas choroid vessel density (P = .03) was larger. The amount of anisometropia had a significant positive correlation with the difference in AL (r = 0.869, P < .001), VCD (r = 0.853, P < .001), and ACD (r = 0.591, P < .001) and a negative correlation with the difference in LT (r = -0.457, P = .009). CONCLUSIONS: Ocular biometrics differ in many aspects between the fellow eyes of anisometropic Chinese children, and the difference is correlated with the degree of anisometropia.

Spectrum of Binocular Vision Anomalies in Keratoconus Subjects.

Keratoconus (KC) is typically a bilateral asymmetric corneal condition associated with anisometropia. A detailed evaluation of binocular vision function is therefore a critical component of ocular examination in these patients for early detection and treatment of binocular vision anomalies. PURPOSE: The purposes of this study were to measure the various parameters of binocular vision (BV) in patients with KC and to identify the factors that possibly influence them. METHODS: This was a prospective, observational study of BV in patients with KC and with best-corrected visual acuity ≤0.4 logMAR in each eye. Age-matched, nonstrabismic normal patients served as controls. Binocular vision examination included motor assessment, accommodation parameters, and fusional vergence. RESULTS: Binocular vision parameters of 84 KC patients were compared with those of 71 normal controls. The KC group showed statistically significant differences between fellow eyes in refractive cylinder (0.44 ± 2.1 D, P = .03), best-corrected visual acuity (0.06 ± 0.09 logMAR, P = .001), and maximum keratometry (6.64 ± 8.2D, P = .005). The control group showed no significant difference in any refractive or keratometric parameter between fellow eyes. Sixty-six (78.6%) of 84 KC patients had various combinations of BV anomalies: 48.8% had impaired stereopsis, 44% had abnormal fusional vergence, and 39.3% had accommodative infacility. Among individual parameters, all except accommodative amplitudes and negative distance fusional vergence showed statistically significant impairment compared with controls (P < .001). Median (interquartile range) stereoacuity was 70 (50 to 550) arc sec in the KC group and 40 (30 to 50) arc sec in control (P < .0001). There was a statistically significant but weak correlation between stereoacuity and positive fusional vergence for near (P = .008; Spearman coefficient, -0.28) and weak but significant negative correlation between phoria status and negative fusional vergence for near (P = .03; Spearman coefficient, -0.24). CONCLUSIONS: A large proportion of KC patients have BV anomalies. Assessment of BV function should be included in the clinical examination of all KC patients.

Effects of simulated anisometropia and aniseikonia on stereopsis.

PURPOSE: Stereopsis depends on horizontally disparate retinal images but otherwise concordance between eyes. Here we investigate the effect of spherical and meridional simulated anisometropia and aniseikonia on stereopsis thresholds. The aims were to determine effects of meridian, magnitude and the relative effects of the two conditions. METHODS: Ten participants with normal binocular vision viewed McGill modified random dot stereograms through synchronised shutter glasses. Stereoacuities were determined using a four-alternative forced-choice procedure. To induce anisometropia, trial lenses of varying power and axes were placed in front of right eyes. Seventeen combinations were used: zero (no lens) and both positive and negative, 1 and 2 D powers, at 45, 90 and 180 axes; spherical lenses were also tested. To induce aniseikonia 17 magnification power and axis combinations were used. This included zero (no lens), and 3%, 6%, 9% and 12% at axes 45, 90 and 180; overall magnifications were also tested. RESULTS: For induced anisometropia, stereopsis loss increased as cylindrical axis rotated from 180° to 90°, at which the loss was similar to that for spherical blur. For example, for 2 D meridional anisometropia threshold increased from 1.53 log sec arc (i.e. 34 sec arc) for x 180 to 1.89 log sec arc (78 sec arc) for x 90. Anisometropia induced with either positive or negative lenses had similar detrimental effects on stereopsis. Unlike anisometropia, the stereopsis loss with induced meridional aniseikonia was not affected by axis and was about 64% of that for overall aniseikonia of the same amount. Approximately, each 1 D of induced anisometropia had the same effect on threshold as did each 6% of induced aniseikonia. CONCLUSION: The axes of meridional anisometropia but not aniseikonia affected stereopsis. This suggests differences in the way that monocular blur (anisometropia) and interocular shape differences (aniseikonia) are processed during the production of stereopsis.

Ciliary muscle morphology and accommodative lag in hyperopic anisometropic children.

PURPOSE: To investigate the cross-sectional area (CSA) and thickness of the ciliary muscle and their correlation with accommodative lag in hyperopic anisometropic children. METHODS: Forty children aged between 6 and 10 years with hyperopic anisometropia were recruited. The more hyperopic eye (mean refractive power of 3.51 ± 1.70 D) was compared with the less hyperopic eye (mean refractive power of 0.78 ± 1.41 D). The thickness and CSA of the ciliary muscle were measured with anterior segment optical coherence tomography (OCT) images at four meridians. The differences between the eyes and the correlations between CSA, thickness, axial length and accommodative lag were accessed. RESULTS: There was no statistically significant difference in CSA between the two groups at any meridian, except at the inferior meridian (P < 0.05). There was no statistically significant difference in ciliary muscle thickness between eyes at any meridian, except on the temporal and the nasal meridians (P < 0.05). There was a significant difference in the ratio of CSA to axial length at all meridians between the two groups (all P < 0.05). Accommodative lag was 1.65 ± 0.55 D and 0.93 ± 0.45 D in the more and less hyperopic eyes, respectively, which was a statistically significant difference (P < 0.05). There was no significant correlation between the CSA with the axial length and the accommodative lag. CONCLUSIONS: This study demonstrated a greater degree of accommodative lag in the more hyperopic eye of anisometropic children. There was no correlation among accommodative lag, axial length and CSA of the ciliary muscle with the degree of hyperopia.

Can the Red Reflex Test Detect Unequal Refractive Error?

OBJECTIVE: To determine the accuracy of the red reflex test in the detection of anisometropia. STUDY DESIGN: This prospective, single-masked study enrolled new patients younger than the age of 18 years who had not undergone pharmacologic pupillary dilation. A fellow who was masked to all clinical information illuminated both eyes with a direct ophthalmoscope in a darkened room from a distance of 1 m, assessing whether the red reflex between the 2 eyes was symmetric or asymmetric. The patient was then dilated, and cylcoplegic refraction was performed by an attending pediatric ophthalmologist. Exclusion criteria included the presence of strabismus, anisocoria, previous intraocular surgery, media opacity, leukocoria, or nystagmus. Sensitivity was compared with a null hypothesized value of 50% using a 1-sided binomial test. RESULTS: Ninety-two patients with a mean age of 7.3 years (range 3 months to 16 years) were enrolled. With spherical anisometropia greater than or equal to 0.125 diopters, the sensitivity of the red reflex test was 90.6% and the specificity was 58.3%. With cylindrical anisometropia greater than or equal to 0.25 diopters, the sensitivity of the red reflex test was 81.3% and the specificity was 70%. Anisometropia greater than 1.5 diopters in spherical equivalent (4 patients, range -10.625 to -2.625) or cylinder (3 patients, range 1.75-2.25) was accurately detected by red reflex testing in each case. CONCLUSIONS: The red reflex test can be an accurate screening tool to detect anisometropia when performed by an ophthalmologist.

A Randomized Clinical Trial of Immediate versus Delayed Glasses for Moderate Hyperopia in 1- and 2-Year-Olds.

PURPOSE: Two strategies were compared for managing moderate hyperopia without manifest strabismus among 1- and 2-year-old children: (1) immediate prescription of glasses versus (2) observation without glasses unless reduced distance visual acuity (VA), reduced stereoacuity, or manifest strabismus. DESIGN: Prospective randomized clinical trial. PARTICIPANTS: A total of 130 children aged 1 to 2 years with hyperopia between +3.00 diopters (D) and +6.00 D spherical equivalent (SE) in at least 1 eye, anisometropia ≤1.50 D SE, and astigmatism ≤1.50 D based on cycloplegic refraction and no manifest strabismus. METHODS: Participants were randomly assigned to glasses (1.00 D less than full cycloplegic hyperopia) versus observation and followed every 6 months for 3 years. Glasses were prescribed to those assigned to observation if they met prespecified deterioration criteria of distance VA or near stereoacuity below age norms, or development of manifest strabismus. MAIN OUTCOME MEASURES: At the 3-year primary outcome examination, participants were classified as failing the randomized management regimen if distance VA or stereoacuity was below age norms or manifest strabismus was observed (each with and without correction in trial frames, confirmed by masked retest, irrespective of whether deterioration had occurred previously), or if strabismus surgery had been performed. RESULTS: Of the 106 participants (82%) completing the 3-year primary outcome examination, failure occurred in 11 (21%) of 53 in the glasses group and 18 (34%) of 53 in the observation group (difference = -13%; 95% confidence interval [CI], -31 to 4; P = 0.14). Sixty-two percent (95% CI, 49-74) in the observation group and 34% (95% CI, 23-48) in the glasses group met deterioration criteria (requiring glasses if not wearing). CONCLUSIONS: For 1- and 2-year-olds with uncorrected moderate hyperopia (+3.00 D to +6.00 D SE), our estimates of failure, after 3 years of 6-month follow-ups, are inconclusive and consistent with a small to moderate benefit or no benefit of immediate prescription of glasses compared with careful observation (with glasses only if deteriorated).

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.

Effect of Orthokeratology on Axial Length Elongation in Anisomyopic Children.

SIGNIFICANCE: Anisomyopia is a natural experimental paradigm that compares dose response between fellow eyes. This study is the first to explore whether orthokeratology (ortho-k) has a dose-response effect on axial length growth and reduces the interocular difference in axial length in anisomyopic children. PURPOSE: The purpose of this study was to compare the effect of ortho-k on axial length elongation between the fellow eyes of anisomyopic children. METHODS: In this retrospective study, 49 anisomyopic children who wore ortho-k lenses were assigned to the anisomyopic ortho-k group. Based on the one-to-one match principle (same age and proximate spherical equivalent), high-isomyopic and low-isomyopic groups each enrolled 49 isomyopic children who wore ortho-k lenses with spherical equivalent similar to that of the more myopic eye and the less myopic eye in the anisomyopic ortho-k group, respectively. Forty-nine anisomyopic children who wore spectacles were enrolled in the anisomyopic spectacle group. At baseline and at 1- and 2-year visits, axial length was measured. Axial length elongation and interocular difference in axial length were compared. RESULTS: In the anisomyopic ortho-k group, the less myopic eyes exhibited more axial length elongation than did the more myopic eyes during 1- and 2-year treatment periods (P < .01). However, there was no significant difference in axial length elongation between the fellow eyes in the isomyopic groups and anisomyopic spectacle group. At the 2-year visit, the interocular difference in axial length of children in the anisomyopic ortho-k group significantly decreased from 0.72 ± 0.34 to 0.56 ± 0.38 mm (P < .05). In contrast, ortho-k lens-wearing isomyopic children or spectacle-wearing anisomyopic children did not show a significant change in interocular difference in axial length. CONCLUSIONS: Orthokeratology could reduce the amount of anisomyopia in children primarily through stronger myopia control in the more myopic eye.

Surgical Timing for Congenital Ptosis Should Not Be Determined Solely by the Presence of Anisometropia.

PURPOSE: Timing of surgery in children with congenital ptosis is a critical component of care, and anisometropia is frequently cited as an indication for early intervention. The purpose of this study is to evaluate the change in refractive error following surgery for congenital ptosis to better inform decisions regarding the timing of surgery. METHODS: A retrospective review of clinical records was performed on patients who underwent surgical correction of congenital ptosis in an academic oculoplastic surgery practice from 2002 to 2017. Patients with complete preoperative and postoperative refractive data were included in the study. Changes in refractive error following surgery were analyzed. RESULTS: Among 184 pediatric patients who underwent ptosis surgery during the study period, 56 patients (71 eyes) met inclusion criteria. The mean age at surgery was 5.1 years. Mean refractive error change in all the operated eyes was a 0.82 D decrease in spherical equivalent (p = 0.1920) and a 0.40 D increase in cylinder (p = 0.0255). There were no statistically significant changes in spherical equivalent or cylinder in the control eyes. CONCLUSIONS: The authors data did not show movement toward normalization of refractive error following ptosis surgery. In fact, it showed a statistically significant worsening of astigmatism following surgery. Because refractive error does not improve following surgery, anisometropia should not be the sole indication for early surgery in congenital ptosis.

ASYMMETRIC DIABETIC RETINOPATHY PROGRESSION IN PATIENTS WITH AXIAL ANISOMETROPIA.

PURPOSE: To investigate the differences in the progression of diabetic retinopathy (DR) in both eyes of patients with axial anisometropia. METHODS: A retrospective review was conducted on diabetic patients who had different axial lengths (difference greater than 1 mm) in each eye. The primary objective of this study was to analyze the differences in the progression of DR in both eyes of patients with axial anisometropia. Fundus images (fluorescein angiography and photographs of the fundus covering the Early Treatment Diabetic Retinopathy Study seven fields) were graded using the Early Treatment Diabetic Retinopathy Study DR grading system. Also, the severity of diabetic retinopathy was analyzed based on the axial length and subfoveal choroidal thickness. RESULTS: Thirty-four of 6,963 patients with DR were included after applying the exclusion and inclusion criteria. The mean age was 53.53 ± 12.20 years and duration of diabetes was 9.63 ± 7.73 years. The mean axial length of the longer and shorter eye was 26.21 ± 2.04 mm and 23.21 ± 1.73 mm, respectively (P < 0.001). In shorter eyes, 61.7% (21 of 34) of the eyes had proliferative diabetic retinopathy. In contrast to the shorter eye, only 8 of the longer eyes (8 of 34, 23.5%) had proliferative diabetic retinopathy (McNemar test, P < 0.001). In eyes with thin subfoveal choroidal thickness (<250 µm), the proliferative diabetic retinopathy ratio was significantly lower (P = 0.007). CONCLUSION: In patients with axial anisometropia, the longer eye had a lower degree of DR progression than the shorter eye. This result showed that elongation of the axial length had a protective effect against the progression of DR without individual confounding factors.

Interocular Comparison of Anterior and Posterior Segment Findings and Laterality in Hyperopic Anisometropia.

OBJECTIVES: To investigate the laterality and the differences in anterior and posterior segment findings in hyperopic patients with anisometropia between their eyes using spectral domain optical coherence tomography and LenStar LS-900 device. METHODS: This prospective institutional study included hyperopic anisometropic patients with and without amblyopia, aged between 6 and 40 years. The refractive error and the values of keratometry, axial length (AL), central corneal thickness (CCT), peripapillary retinal nerve fiber layer (RNFL) thickness, and central macular thickness (CMT) obtained using the RK-F1 autorefractor, LenStar LS-900, and Spectralis optical coherence tomography were compared between the higher hyperopic and fellow eyes. RESULTS: Eighty of the patients had hyperopic anisometropia with amblyopia and 30 of them had hyperopic anisometropia without amblyopia. The left eyes of the patients in this series were significantly more commonly affected. Axial length and CCT were significantly different between the higher hyperopic and the fellow eyes of all patients. In addition, the mean CMT and RNFL thickness of the higher hyperopic eyes were significantly higher than that of the fellow eyes. CONCLUSIONS: During the process of emmetropization and development of the retina, higher hyperopic eyes in hyperopic patients with anisometropia and amblyopic eyes may have blurred and abnormal vision, leading to under-development of vision, significantly higher CCT, CMT, and RNFL thickness, more hyperopic refraction, and shorter AL in the affected eye.

Binocular benefits of optical treatment in anisometropic amblyopia.

In this study, we investigated the effect of optical treatment on sensory eye balance in anisometropic amblyopia. Fourteen individuals (age: 13.7 ± 8.4 years old) with previously untreated anisometropic amblyopia were enrolled in the study. The average magnitude of their anisometropia (spherical equivalent) was 4.02 ± 1.19 DS. Their best corrected monocular visual acuity and sensory eye balance were measured before and after a 2-month period of full refractive correction (i.e., our optical treatment). Spectacle-corrected distance visual acuity (at 5 m) was measured monocularly using the Tumbling E Chart. Sensory eye balance was quantitatively assessed using a binocular phase-combination paradigm to determine the interocular contrast ratio at which the two eyes were balanced in binocular sensory combination (i.e., the balance point). We found that both interocular contrast ratio at the balance point (p = 0.006) and visual acuity of the amblyopic eye (p < 0.001) were significantly improved after 2 months of optical treatment, often referred to as refractive adaptation. We conclude that sustained optical treatment improves interocular sensory balance in anisometropic amblyopia as well as monocular acuity. Optical treatment is a passive form of binocular therapy and a necessary first step in treating the binocular dysfunction that characterizes amblyopia.

Stereopsis and fusion in anisometropia according to the presence of amblyopia.

PURPOSE: To evaluate the level of stereopsis and fusion in patients with anisometropia according to the presence of amblyopia. METHODS: We included 107 children with anisometropia, divided into groups with non-amblyopic anisometropia (NA, n = 72) and amblyopic anisometropia (AA, n = 35). Normal subjects without anisometropia were enrolled in the control group (n = 73). Main outcome measures were the level of stereopsis and sensory fusion as evaluated by Titmus stereotest and Worth 4-dot test, respectively, using anisometropic glasses. RESULTS: The degree of anisometropia in the NA, AA, and control groups was 2.54 diopters (D), 4.29 D, and 0.30 D, respectively (P = 0.014). Stereopsis (arcsec) was significantly worse in the AA group than the NA and control groups (641.71, 76.25, 54.52, respectively, P < 0.001), while no significant difference was found between the NA and control groups. The rate of fusion was significantly lower in the AA than the NA group (14.3% vs. 65.3%, P < 0.001), and was significantly lower in the NA than the control group (65.3% vs. 80.6%, P = 0.001). CONCLUSIONS: The levels of stereopsis and sensory fusion with anisometropic glasses were significantly worse in the AA than in the NA group. The level of stereopsis in the NA group, however, did not differ significantly from that in the isometropic control, while the rate of fusion was significantly lower. Early prescription of anisometropic glasses is needed to improve visual acuity and binocularity in children with possible amblyopic anisometropia.

Acuity-independent effects of visual deprivation on human visual cortex.

Visual development depends on sensory input during an early developmental critical period. Deviation of the pointing direction of the two eyes (strabismus) or chronic optical blur (anisometropia) separately and together can disrupt the formation of normal binocular interactions and the development of spatial processing, leading to a loss of stereopsis and visual acuity known as amblyopia. To shed new light on how these two different forms of visual deprivation affect the development of visual cortex, we used event-related potentials (ERPs) to study the temporal evolution of visual responses in patients who had experienced either strabismus or anisometropia early in life. To make a specific statement about the locus of deprivation effects, we took advantage of a stimulation paradigm in which we could measure deprivation effects that arise either before or after a configuration-specific response to illusory contours (ICs). Extraction of ICs is known to first occur in extrastriate visual areas. Our ERP measurements indicate that deprivation via strabismus affects both the early part of the evoked response that occurs before ICs are formed as well as the later IC-selective response. Importantly, these effects are found in the normal-acuity nonamblyopic eyes of strabismic amblyopes and in both eyes of strabismic patients without amblyopia. The nonamblyopic eyes of anisometropic amblyopes, by contrast, are normal. Our results indicate that beyond the well-known effects of strabismus on the development of normal binocularity, it also affects the early stages of monocular feature processing in an acuity-independent fashion.

Effect of myopic anisometropia on anterior and posterior ocular segment parameters.

The purpose of this study is to investigate the differences in anterior and posterior segment parameters of more myopic eyes compared to fellow eyes using spectral domain optical coherence tomography and optical biometer device in patients with myopic anisometropia. This prospective cross-sectional study included 42 myopic anisometropic patients with and without amblyopia, aged between 7 and 40 years old. The refractive error and keratometry values, axial length (AL), central corneal thickness (CCT), peripapillary retinal nerve fiber layer thickness (RNFLT), and central macular thickness (CMT) were evaluated. Eighteen of the patients had myopic anisometropia with amblyopia, and the remaining 24 had myopic anisometropia without amblyopia. There were 23 female and 19 male patients with a mean age as 23.67 ± 10.12 years (range 7-40). The right eyes of the subjects significantly had a higher degree of myopia. There was a significant difference in mean best-corrected visual acuity (0.195 ± 0.234 vs. 0.011 ± 0.025 logMAR, p < 0.001), spherical equivalent refraction (-3.95 ± 1.38 vs. -1.04 ± 0.99 D, p < 0.001), AL (25.06 ± 1.27 vs. 23.99 ± 0.98 mm, p < 0.001), and RNFLT (89.24 ± 12.84 vs. 94.57 ± 10.81 µm, p < 0.001) between the more myopic and fellow eyes in all patients. On the contrary, there was no significant difference in CMT and anterior segment parameters including mean keratometry and CCT in all patients and either group. During the development of the myopic anisometropia, more myopic eyes have significantly more myopic refraction, longer AL and thinner RNFLT compared to the fellow eyes.