Lens power, cornea power and association with refractive error in children with moderate to high hyperopia.

OBJECTIVE: This study aimed to profile ocular biometry parameters and predictors of spherical equivalent refraction (SER) among children with moderate to high hyperopia. METHODS: Individuals <18 years of age with moderate to high hyperopia were enrolled from November 2015 to November 2021. Participants underwent a series of comprehensive ocular examinations, and were classified as having low hyperopia, that is, SER +0.5 to < +2.0 D or moderate to high hyperopia, that is, SER ≥ +2.0 D. RESULTS: A total of 459 and 230 eyes with moderate to high hyperopia and low hyperopia, respectively, were included. Moderate to high hyperopic eyes had a shorter axial length, stronger lens power (24.78 ± 5.47 D vs. 18.74 ± 1.63 D, p < 0.001) and weaker corneal power (42.82 ± 1.75 D vs. 43.31 ± 1.55 D, p < 0.001) than low hyperopic eyes. When comparing values before and after 5 years of age, both lens power and axial length differed significantly in the moderate to high hyperopia group, whereas in the low hyperopia group, they only differed significantly after 9 years of age. Lens power was negatively associated with AL in eyes with axial lengths between 20 and 22 mm. A multiple linear regression model which included axial length (standardised ß = -0.80, p < 0.001), corneal power (standardised ß = -0.47, p < 0.001) and lens power (standardised ß = 0.23, p < 0.001) explained 81.2% of the variance in SER. CONCLUSIONS: Differences in lens power and axial length in moderate to high hyperopic eyes became significantly smaller after 5 years of age, at least 4 years earlier than for the low hyperopia. Lens power could offset the axial elongation in participants with axial lengths between 20 and 22 mm, suggesting that children with moderate to high hyperopia might have different ocular growth patterns. Axial length, corneal power and lens power were the main predictors of SER in moderate to high hyperopia.

Topographical profiles of macula and optic nerve head in concomitant strabismus patients as measured using OCT and CSLO.

PURPOSE: Investigate morphological changes of macula and optic nerve head (ONH) in concomitant strabismic patients using optical coherence tomography (OCT) and confocal scanning laser ophthalmoscopy (CSLO). METHODS: A cross-sectional study conducted from April 2017 to February 2018 at the Zhongshan Ophthalmic Center, Sun Yat-sen University. Spectral-domain (SD)-OCT and CSLO were used to observe morphological changes of macula and ONH in concomitant strabismic patients with normal vision and healthy controls. In each subject, a 6-mm diameter zone centered at the fovea was scanned and topographical images of the ONH and peripapillary retina were generated. Fundus parameters were recorded and analyzed. RESULTS: A total of 138 cases, including 29 patients with concomitant esotropia (ET), 38 constant exotropia (XT), 42 intermittent exotropia (IXT), and 29 healthy controls, were recruited. Compared with controls, OCT revealed that the thickness of nasal intraretinal layers (IRLs) in ET patients was significantly increased, particularly in ganglion cell layer (GCL) and inner nuclear layer (INL). In XT patients, the temporal half of outer retinal layers (ORLs) showed significant increases in thickness. CSLO findings revealed significant changes in the ONH of ET patients consisting of a thinner retinal nerve fiber layer (RNFL) and a decreased RNFL cross-sectional area, height variation contour, maximum contour depression, and contour line modulation (CLM) temporal-superior area. The nasal-superior cup area and rim volume in XT patients were significantly increased. CONCLUSION: Topographical profiles of the macula and ONH in concomitant strabismic patients with normal vision present with specific regularities.

Intermediate filaments in the medial rectus muscles in patients with concomitant exotropia.

PURPOSE: Distribution of intermediate filament (IF) proteins in normal extraocular muscles (EOMs) showed that the EOMs differ significantly from the other muscles in the body with respect to their IFs composition, including desmin and nestin. The aim of the present study was to investigate the pathological changes in the medial rectus (MR) in patients with concomitant exotropia (XT). METHODS: Forty-six MR muscle samples from 46 patients with XT were analyzed pathologically and processed for immunohistochemistry with specific antibodies against desmin and nestin. RESULTS: Although most of MR muscles remained normal structures relatively, they presented high expression of desmin, and in contrast, nestin was absent in a large proportion of the MR muscles. CONCLUSION: Desmin, which is downregulated in normal EOMs, had high expression in MR muscles of patients with XT. Nestin, which is present in a high proportion of normal EOMs, was downregulated in MR muscles of patients with XT.

Impact of Online Video Game-Based Dichoptic Training on Binocular Vision Rehabilitation in Post-surgical Patients with Intermittent Exotropia.

INTRODUCTION: Dichoptic training has emerged as a promising rehabilitation approach for improving binocular visual function in patients with strabismus. A prospective observational study design was employed to assess the effectiveness of online video game-based dichoptic training in rehabilitating binocular visual function in patients who had undergone an operation for intermittent exotropia. METHODS: A total of 64 patients who had undergone an operation for intermittent exotropia were recruited and divided into the training group and the control group based on whether they would receive the dichoptic training. The dichoptic training was conducted for 3 months in the training group and the control group would not accept any form of orthoptic therapy. Assessments of binocular visual functions and deviation were conducted at baseline, 3-month and 6-month follow-up. RESULTS: Twenty-nine participants in the training group (mean 9.69 ± 2.66 years old) and 26 participants in the control group (mean 8.41 ± 2.64 years old) completed follow-up. At both 3- and 6-month follow-ups, the training group showed superior distance stereopsis compared to the control group, with near stereopsis only showing significant difference at the 6-month follow-up. Additionally, the training group exhibited significantly less distance exo-deviation drift than the control group at these times, and no significant difference was observed in near exo-deviation drift between the groups. The control group had a significantly higher rate of suboptimal surgical outcomes at both the 3- and 6-month follow-up. However, no significant differences were observed in simultaneous perception and fusion functions between the two groups. CONCLUSIONS: Online video game-based dichoptic training has the potential to become a novel postoperative rehabilitation strategy for patients with intermittent exotropia.

Quantitative measurement of interocular suppression in anisometropic amblyopia: a case-control study.

OBJECTIVE: The aims of this study were to assess (1) the relationship between interocular suppression and visual function in patients with anisometropic amblyopia, (2) whether suppression can be simulated in matched controls using monocular defocus or neutral density filters, (3) the effects of spectacle or rigid gas-permeable contact lens correction on suppression in patients with anisometropic amblyopia, and (4) the relationship between interocular suppression and outcomes of occlusion therapy. DESIGN: Case-control study (aims 1-3) and cohort study (aim 4). PARTICIPANTS: Forty-five participants with anisometropic amblyopia and 45 matched controls (mean age, 8.8 years for both groups). METHODS: Interocular suppression was assessed using Bagolini striated lenses, neutral density filters, and an objective psychophysical technique that measures the amount of contrast imbalance between the 2 eyes that is required to overcome suppression (dichoptic motion coherence thresholds). Visual acuity was assessed using a logarithm minimum angle of resolution tumbling E chart and stereopsis using the Randot preschool test. MAIN OUTCOME MEASURES: Interocular suppression assessed using dichoptic motion coherence thresholds. RESULTS: Patients exhibited significantly stronger suppression than controls, and stronger suppression was correlated significantly with poorer visual acuity in amblyopic eyes. Reducing monocular acuity in controls to match that of cases using neutral density filters (luminance reduction) resulted in levels of interocular suppression comparable with that in patients. This was not the case for monocular defocus (optical blur). Rigid gas-permeable contact lens correction resulted in less suppression than spectacle correction, and stronger suppression was associated with poorer outcomes after occlusion therapy. CONCLUSIONS: Interocular suppression plays a key role in the visual deficits associated with anisometropic amblyopia and can be simulated in controls by inducing a luminance difference between the eyes. Accurate quantification of suppression using the dichoptic motion coherence threshold technique may provide useful information for the management and treatment of anisometropic amblyopia. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Overexpression of Six1 leads to retardation of myogenic differentiation in C2C12 myoblasts.

The Six1 homeoprotein belongs to the Six (sine oculis) transcription factor family, the members of which are known to act as master regulators of development. Six1 is essential for promoting myogenesis during mammalian somitogenesis. Previous studies have shown that Six1 participates in later steps of myogenic differentiation by enhancing early activation of myogenin via binding to the Mef3 site of the myogenin promoter. In the present study, however, we show that overexpression of Six1 via retroviral infection suppresses the expression of myogenin and myosin in C2C12 myoblasts, consequently retarding myogenic differentiation without affecting cell proliferation or expression of Mef2 and Mef3. These findings further demonstrate the functional role of Six1 in myogenesis.

How best to assess suppression in patients with high anisometropia.

PURPOSE: We have recently described a rapid technique for measuring suppression using a dichoptic signal/noise task. Here, we report a modification of this technique that allows for accurate measurements to be made in amblyopic patients with high levels of anisometropia. This was necessary because aniseikonic image size differences between the two eyes can provide a cue for signal/noise segregation and, therefore, influence suppression measurement in these patients. METHODS: Suppression was measured using our original technique and with a modified technique whereby the size of the signal and noise elements was randomized across the stimulus to eliminate size differences as a cue for task performance. Eleven patients with anisometropic amblyopia, five with more than 5 diopters (D) spherical equivalent difference (SED), six with less than 5 D SED between the eyes, and 10 control observers completed suppression measurements using both techniques. RESULTS: Suppression measurements in controls and patients with less than 5 D SED were constant across the two techniques; however, patients with more than 5 D SED showed significantly stronger suppression on the modified technique with randomized element size. Measurements made with the modified technique correlated with the loss of visual acuity in the amblyopic eye and were in good agreement with previous reports using detailed psychophysical measurements. CONCLUSIONS: The signal/noise technique for measuring suppression can be applied to patients with high levels of anisometropia and aniseikonia if element size is randomized. In addition, deeper suppression is associated with a greater loss of visual acuity in patients with anisometropic amblyopia.

Cortical Reorganization After Optical Alignment in Strabismic Patients Outside of Critical Period.

Purpose: To measure visual crowding, an essential bottleneck on object recognition and reliable psychophysical index of cortex organization, in older children and adults with horizontal concomitant strabismus before and after strabismus surgery. Methods: Using real-time eye tracking to ensure gaze-contingent display, we examined the peripheral visual crowding effects in older children and adults with horizontal concomitant strabismus but without amblyopia before and after strabismus surgery. Patients were asked to discriminate the orientation of the central tumbling E target letter with flankers arranged along the radial or tangential axis in the nasal or temporal hemifield at different eccentricities (5° or 10°). The critical spacing value, which is the minimum space between the target and the flankers required for correct discrimination, was obtained for comparisons before and after strabismus surgery. Results: Twelve individuals with exotropia (6 males, 21.75 ± 7.29 years, mean ± SD) and 15 individuals with esotropia (6 males, 24.13 ± 5.96 years) participated in this study. We found that strabismic individuals showed significantly larger critical spacing with nasotemporal asymmetry along the radial axis that related to the strabismus pattern, with exotropes exhibiting stronger temporal field crowding and esotropes exhibiting stronger nasal field crowding before surgical alignment. After surgery, the critical spacing was reduced and rebalanced between the nasal and temporal hemifields. Furthermore, the postoperative recovery of stereopsis was associated with the extent of nasotemporal balance of critical spacing. Conclusions: We find that optical realignment (i.e., strabismus surgery) can normalize the enlarged visual crowding effects, a reliable psychophysical index of cortical organization, in the peripheral visual field of older children and adults with strabismus and rebalance the nasotemporal asymmetry of crowding, promoting the recovery of postoperative stereopsis. Our results indicated a potential of experience-dependent cortical organization after axial alignment even for individuals who are out of the critical period of visual development, illuminating the capacity and limitations of optics on sensory plasticity and emphasizing the importance of ocular correction for clinical practice.

Visual Crowding Reveals Field- and Axis-Specific Cortical Miswiring After Long-Term Axial Misalignment in Strabismic Patients Without Amblyopia.

Purpose: Inspired by physiological and neuroimaging findings that revealed squint-induced modification of cortical volume and visual receptive field in early visual areas, we hypothesized that strabismic eyes without amblyopia manifest an increase in critical spacing of visual crowding, an essential bottleneck on object recognition and reliable psychophysical index of cortical organization. Methods: We used real-time eye tracking to ensure gaze-contingent display and examined visual crowding in patients with horizontal concomitant strabismus (both esotropia and exotropia) but without amblyopia and age-matched normal controls. Results: Nineteen patients with exotropia (12 men, mean ± SD = 22.89 ± 7.82 years), 21 patients with esotropia (10 men, mean ± SD = 23.48 ± 6.95 years), and 14 age-matched normal controls (7 men, mean ± SD = 23.07 ± 1.07 years) participated in this study. We found that patients with strabismus without amblyopia showed significantly larger critical spacing with nasotemporal asymmetry in only the radial axis that related to the strabismus pattern, with exotropia exhibiting stronger temporal hemifield crowding and esotropia exhibiting stronger nasal hemifield crowding, in both the deviated and fixating eyes. Moreover, the magnitude of crowding change was related to the duration and degree of strabismic deviation. Conclusions: Using visual crowding as a psychophysical index of cortical organization, our study demonstrated significantly greater peripheral visual crowding with nasotemporal asymmetry in only the radial axis in patients with strabismus without amblyopia, indicating the existence of hemifield- and axis-specific miswiring of cortical processing in object recognition induced by long-term adaptation to ocular misalignment.

Surgical treatment versus observation in moderate intermittent exotropia (SOMIX): study protocol for a randomized controlled trial.

BACKGROUND: Intermittent exotropia (IXT) is the most common type of strabismus in China, but the best treatment and optimal timing of intervention for IXT remain controversial, particularly for children with moderate IXT who manifest obvious exodeviation frequently but with only partial impairment of binocular single vision. The lack of randomized controlled trial (RCT) evidence means that the true effectiveness of the surgical treatment in curing moderate IXT is still unknown. The SOMIX (surgical treatment versus observation in moderate intermittent exotropia) study has been designed to determine the long-term effectiveness of surgery for the treatment and the natural history of IXT among patients aged 5 to 18 years old. METHODS/DESIGN: A total of 280 patients between 5 and 18 years of age with moderate IXT will be enrolled at Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. After initial clinical assessment, all participants will be randomized to receive surgical treatment or observation, and then be followed up for 5 years. The primary objective is to compare the cure rate of IXT between the surgical treatment and observation group. The secondary objectives are to identify the predictive factors affecting long-term outcomes in each group and to observe the natural course of IXT. DISCUSSION: The SOMIX trial will provide important guidance regarding the moderate IXT and its managements and modify the treatment strategies of IXT. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02736526 . Registered April 13, 2016.

Effectiveness of a short message reminder in increasing compliance with pediatric cataract treatment: a randomized trial.

OBJECTIVE: Regular follow-up is essential to successful management of childhood cataract. We sought to assess whether a mobile phone short message service (SMS) for parents of children with cataract could improve follow-up adherence and the proportion of procedures performed in timely fashion. DESIGN: Randomized, controlled trial. This trial is registered with ClinicalTrials.gov, NCT01417819. PARTICIPANTS: We included 258 parent-child pairs involved in the Childhood Cataract Program of the Chinese Ministry of Health. METHODS: Participants were randomized (1:1) to a mobile phone SMS intervention or standard follow-up appointments. All participants were scheduled to attend ≥ 4 follow-up appointments according to the protocol. Parents in the intervention group received SMS automated reminders before scheduled appointments. The control group parents did not receive SMSs or any alternative reminder of scheduled appointments. Regular ocular examinations and analyses were performed by investigators masked to group allocation; however, study participants and the manager in charge of randomization and sending SMSs were not masked. MAIN OUTCOME MEASURES: Number of follow-up appointments attended, additional surgeries, laser treatments, changes in eyeglasses prescription, and occurrence of secondary ocular hypertension. RESULTS: Among parent-child participants, 135 were randomly assigned to the SMS intervention and 123 to standard appointments. Attendance rates for the SMS group (first visit, 97.8%; second, 91.9%; third, 92.6%; fourth, 83%) were significantly higher than those for the control group (first visit, 87.8%; second, 69.9%; third, 56.9%; fourth, 33.3%). The increase in attendance rate for total number of follow-up visits with SMS reminders was 47.2% (relative risk [RR] for attendance, 1.47; 95% confidence interval [CI], 1.16-1.78; P = 0.003). The number needed to remind (NNR) to gain 1 additional visit by 1 child was 3 (95% CI, 1.8-4.2). A total of 247 clinical interventions were carried out in the SMS group and 134 in the control group (RR, 1.68; 95% CI, 1.37-1.99; P = 0.007). The NNR to result in 1 additional clinical intervention was 5 (95% CI, 3.5-6.5). CONCLUSIONS: The SMS reminders significantly improved follow-up adherence in pediatric cataract treatment. Using readily available mobile phone resources may be an effective and economic strategy to improve management of childhood cataract in China. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

A Dichoptic Optokinetic Nystagmus Paradigm for Interocular Suppression Quantification in Intermittent Exotropia.

Purposes: To investigate the effectiveness of a dichoptic optokinetic nystagmus (dOKN) test to objectively quantify interocular suppression in intermittent exotropia (IXT) patients during the states of orthotropia and exodeviation. Methods: The OKN motion in subjects (15 controls and 59 IXT subjects) who viewed dichoptic oppositely moving gratings with different contrast ratios was monitored and recorded by an eye tracker. Interocular suppression in control subjects was induced using neutral density (ND) filters. The OKN direction ratios were fitted to examine the changes of interocular suppression in subjects under different viewing states. Two established interocular suppression tests (phase and motion) were conducted for a comparative study. Results: The dOKN test, which requires a minimal response from subjects, could accurately quantify the interocular suppression in both IXT and control subjects, which is in line with the established interocular suppression tests. Overall, although comparative, the strength of interocular suppression detected by the dOKN test (0.171 ± 0.088) was stronger than those of the phase (0.293 ± 0.081) and the motion tests (0.212 ± 0.068) in the control subjects with 1.5 ND filters. In IXT patients, when their eyes kept aligned, the dOKN test (0.58 ± 0.09) measured deeper visual suppression compared with the phase (0.73 ± 0.17) or the motion test (0.65 ± 0.14). Interestingly, strong interocular suppression (dOKN: 0.15 ± 0.12) was observed in IXT subjects during the periods of exodeviation, irrespective of their binocular visual function as measured by synoptophore. Conclusion: The dOKN test provides efficient and objective quantification of interocular suppression in IXT, and demonstrates how it fluctuates under different eye positions.

A novel dynamic random-dot stereopsis assessment to measure stereopsis in intermittent exotropia.

BACKGROUND: To investigate dynamic stereopsis in intermittent exotropia [X(T)] patients using a novel dynamic random-dot stereopsis assessment method. METHODS: A novel dynamic random-dot stereopsis test was performed using novel self-programmed software, which consisted of red and green dots and four blocks on the screen. The test included motion + disparity (MD), motion (M), and disparity (D), where the D cues ranged from 200 to 1,200 arc-seconds. The characteristics of preoperative dynamic stereopsis in 83 X(T) patients and associations with clinical features were analysed, and the prognosis was followed up on the 1st day and at the 2nd, 6th and 12th months postoperatively. RESULTS: Preoperatively, the mean reciprocal values of near and far stereopsis were 0.013±0.0016 and 0.0011±0.0005 arc-seconds in static stereopsis patients, respectively, and the MD, M, and D values were 0.002±0.0002, 0.0018±0.0001, and 0.0012±0.0002 arc-seconds in dynamic stereopsis, respectively. The MD value was negatively correlated with the Newcastle control score, disease course, and prism deviations (P<0.05), M was correlated with disease course and the Newcastle control score (P<0.05), and D was not correlated with any clinical features. Postoperative dynamic stereopsis improved from the 1st day and gradually peaked at the 6th month, while static stereopsis showed a decreased tendency in near but not far stereopsis. CONCLUSIONS: The dynamic stereopsis quantitative evaluation method based on random dots is a feasible test and shows that destruction of X(T) patients' dynamic stereopsis is affected by age at surgery, disease course, strabismus controllability and the strabismus degree.

Variant types of Duane retraction syndrome: synergistic divergences and convergences.

PURPOSE: To present the clinical features of 4 patients with Duane retraction syndrome characterized by synergistic divergence or convergence, abnormal vertical movements, and accessory fibrotic bands. METHODS: The medical records of 4 patients were reviewed retrospectively for the following clinical manifestations: visual acuity, refraction, ocular alignments, ocular motility, head position, magnetic resonance imaging, surgical techniques, and outcomes. RESULTS: All 4 cases were diagnosed as variants of Duane retraction syndrome. Two cases (cases 1 and 2) had synergistic divergence with unilateral adduction deficit, and 2 (cases 3 and 4) had synergistic convergence with bilateral abduction deficit. Case 2 manifested abnormal vertical movements of the right eye, which goes down with adduction of the left eye and goes up oppositely with abduction of left eye. Accessory fibrotic bands were detected beside the medial rectus muscle of both eyes in case 3. Synergistic convergence in case 4 occurred only after the first strabismus surgery. Weakening of the misinnervated horizontal rectus muscle improved ocular alignment and head position in cases 1, 3, and 4. CONCLUSIONS: Synergistic divergence and convergence are extremely rare and may present with a great diversity of clinical features. A good outcome is very difficult to achieve; however, weakening of the misinnervated horizontal rectus muscle was therapeutic in these patients.

Anisometropic Amblyopia: Interocular Contrast and Viewing Luminance Effects on Aniseikonia.

Purpose: To demonstrate an aniseikonia test for anisometropic amblyopia (ATAA) that uses variable viewing luminance at different interocular contrast levels. Methods: The test consists of a direct size comparison task based on a computer. The subject is asked to adjust the size of a dichoptically dissociated paired square target. One square was always presented at 100% contrast to the amblyopic eye/nondominant eye, whereas its counterpart was presented to the fellow eye at six contrast levels. Measurements were performed at two luminance backgrounds: (1) a white square on a black background (WoB) and (2) a black square on a white background (BoW). To test the feasibility of this approach, 16 patients with anisometropic amblyopia and 23 normal controls were recruited. Results: The Aniseikonia Index (AI) calculated from the ATAA increased when the difference in the interocular contrast increased in both the patients with anisometropic amblyopia and controls under BoW and WoB conditions. The mean AI differed dramatically between the BoW and WoB conditions in patients with amblyopia but not in normal subjects. Conclusions: Our model predicted interocular differences in contrast to the measurement of aniseikonia. Execution of the AI in individuals with amblyopia should consider that their responses to different luminance viewing conditions could be asymmetric. Translational Relevance: The ATAA has the potential to optimize optical correction for the management of aniseikonia in individuals with anisometropic amblyopia.

A New Dichoptic Training Strategy Leads to Better Cooperation Between the Two Eyes in Amblyopia.

Recent clinical trials failed to endorse dichoptic training for amblyopia treatment. Here, we proposed an alternative training strategy that focused on reducing signal threshold contrast in the amblyopic eye under a constant and high noise contrast in the fellow eye (HNC), and compared it to a typical dichoptic strategy that aimed at increasing the tolerable noise contrast in the fellow eye (i.e., TNC strategy). We recruited 16 patients with amblyopia and divided them into two groups. Eight patients in Group 1 received the HNC training, while the other eight patients in Group 2 performed the TNC training first (Phase 1) and then crossed over to the HNC training (Phase 2). We measured contrast sensitivity functions (CSFs) separately in the amblyopic and fellow eyes when the untested eye viewed mean luminance (monocularly unmasked) or noise stimuli (dichoptically masked) before and after training at a particular frequency. The area under the log contrast sensitivity function (AULCSF) of masked and unmasked conditions, and dichoptic gain (the ratio of AULCSF of masked to unmasked condition) were calculated for each eye. We found that both dichoptic training paradigms substantially improved masked CSF, dichoptic gain, and visual acuity in the amblyopic eye. As opposed to the TNC paradigm, the HNC training produced stronger effects on masked CSFs, stereoacuity, dichoptic gain, and visual acuity in the amblyopic eye. Interestingly, the second-phase HNC training in Group 2 also induced further improvement in the masked contrast sensitivity and AULCSF in the amblyopic eye. We concluded that the HNC training strategy was more effective than the TNC training paradigm. Future design for dichoptic training should not only focus on increasing the tolerable noise contrast in the fellow eye but should also "nurture" the amblyopic eye under normal binocular viewing conditions and sustained interocular suppression.

Objective Assessment of the Effect of Optical Treatment on Magnocellular and Parvocellular-biased Visual Response in Anisometropic Amblyopia.

Purpose: Optical treatment can improve visual function in anisometropic amblyopia, but there is no electrophysiological evidence, and the underlying change in visual pathway remains unknown. Our aims were to characterize the functional loss in magnocellular and parvocellular visual pathways in anisometropic amblyopia at baseline and to investigate the effect of optical treatment on the 2 visual pathways. Methods: Using isolated-check visual-evoked potential, we measured the magnocellular- and parvocellular-biased contrast response functions in 15 normal controls (20.13 ± 3.93 years; mean ± standard deviation), 16 patients with anisometropic amblyopia (18.00 ± 6.04 years) who were fully refractive corrected before and 29 (19.41 ± 7.41 years) who had never been corrected. Twelve previously uncorrected amblyopes received optical treatment for more than 2 months and finished the follow-up measurement. Results: Both the magnocellular- and parvocellular-biased contrast response functions in the amblyopic eye exhibited significantly reduced response and weaker contrast gains. We also found that the uncorrected amblyopes showed a more severe response reduction in magnocellular-biased, but not parvocellular-biased condition when compared with those corrected, with a weaker initial contrast gain and lower maximal response. After optical treatment, 12 uncorrected amblyopes demonstrated improved visual acuity of the amblyopic eye and a significant response gain to magnocellular-biased but not parvocellular-biased stimuli. Conclusions: We demonstrated deficits to both magnocellular- and parvocellular-biased stimuli in subjects with anisometropic amblyopia. Optical treatment could produce neurophysiological changes in visual pathways even in older children and adults, which may be mediated through the magnocellular pathway.

Quantifying Nasotemporal Asymmetry of Interocular Suppression in Alternating Strabismus After Correction.

Purpose: This study identifies and characterizes the nasotemporal hemifield difference of interocular suppression in subjects who have been successfully treated for strabismus. Methods: Interocular suppression in the nasal and temporal hemifields were measured using two methods, namely, binocular phase combination and dichoptic motion coherence, both entailed suprathreshold stimuli. We tested 29 clinical subjects, who had strabismus (19 with exotropia and 10 with esotropia) but regained good ocular alignment (within 10 prism diopters) after surgical or refractive correction, and 10 control subjects. Results: Both the hemifield binocular phase combination and the hemifield dichoptic motion coherence tests revealed similar nasotemporal asymmetry of interocular suppression. Subjects with previous exotropia showed deeper suppression in the nasal hemifield, and those with previous esotropia showed deeper suppression in the temporal hemifield. This finding was consistent with the hemifield suppression theory. Furthermore, there was deeper suppression but less imbalance of nasotemporal asymmetry in the hemifield dichoptic motion coherence test. Finally, clinical stereopsis and the nasotemporal asymmetry of suppression (P < 0.05 in both tests) were negatively correlated in subjects with previous exotropia and measurable stereopsis. Conclusions: Hemifield asymmetry of interocular suppression in corrected strabismus can be measured by using static and dynamic suprathreshold stimuli. Thus, the evaluation of binocular vision in strabismus should focus on both the magnitude and the pattern of interocular suppression.

Evaluation of dynamic stereopsis in intermittent exotropia patients.

AIM: To delineate the characteristics of the dynamic stereopsis test and analyze related parameters in intermittent exotropia [X(T)] patients. METHODS: Fifty-seven X(T) patients and 55 normal subjects were enrolled in this study. The normal and X(T) groups were used to test the reproducibility and reliability of the dynamic stereopsis test, and Bangerter filters with densities of 0.2 were then used to simulate suppression to test for traditional and dynamic stereopsis. In the X(T) group, the measurements included 1) dynamic stereopsis test comprising three parts: motion+disparity, motion only and disparity only; 2) ocular deviation angle; 3) Bagolini striated lens test; 4) disease course; and 5) Titmus stereopsis test. RESULTS: The test-retest reliability of the dynamic stereopsis method was 0.901 in the normal and X(T) groups, and none of the X(T) patients were able to pass the static and dynamic stereopsis tests after using the 0.2 Bangerter filter. The accuracy rate was greater than 80% in the normal group and 31.81%, 36.36%, and 45.45% for the motion+disparity, motion-only and disparity-only components of the traditional test for X(T) patients diagnosed with stereoblindness via traditional tests, respectively. Patients with a long disease course (>1y) had worse dynamic stereopsis than those with a short disease course (<1y; P<0.05, Chi-square test). The deviation angle was not correlated with the motion+disparity, disparity-only, or the motion-only test components (all P>0.05, Chi-square test). CONCLUSION: Dynamic stereopsis is preserved in certain X(T) patients diagnosed with stereoblindness via traditional tests. A long disease course was shown to be a negative factor for dynamic stereopsis in X(T) patients which might be associated with worse progression, and provide good references clinically.

Long-term visual outcome of dense bilateral congenital cataract.

BACKGROUND: Dense congenital cataracts often cause severe visual impairment. The results of long-term follow-up of dense bilateral congenital cataract in China have not been well documented. The purpose of this study was to evaluate the long-term visual function in children who underwent cataract extraction for dense bilateral congenital cataract in southern part of China. METHODS: Medical records of children who underwent surgery of dense bilateral congenital cataract between January 1992 and December 2000 at Zhongshan Ophthalmic Center of Sun Yat-sen University were retroactively reviewed. In 38 children available for current follow-up, best corrected visual acuity (BCVA) and stereoscopic vision, as well as nystagmus, strabismus, and other complications, were evaluated. The mean follow-up period was 107.6 months (range 60 to 167 months). RESULTS: The mean age of cataract extraction and secondary intraocular lens implantation were 5.6 months (range 3 to 12 months) and 4.2 years (range 2.4 to 15 years), respectively. The mean BCVA was 0.25 in the better eye and 0.16 in the fellow eye. Stereoscopic vision was absent in all patients, and 3 children had simultaneous perception. Nystagmus was detected in all cases and strabismus in 35 cases. A high correlation was found between timing of cataract extraction and final BCVA of the better eye (r = -0.55, P = 0.00). A statistically significant difference was found in BCVA between post- and pre-treatment of amblyopia (t = 5.65, P = 0.00). CONCLUSIONS: Long-term visual function in children with dense bilateral congenital cataract was poor when cataract surgery was performed at age of 3 months or later. Earlier cataract surgery with adequate optical rehabilitation contributed to better visual outcome.