Efficacy of anti-suppression therapy in improving binocular vision in children with small-angle Esotropia

Purpose: To evaluate the efficacy of anti-suppression exercises in children with small-angle esotropia in achieving binocular vision. Methods: A retrospective review of patients aged 3–8 years who underwent anti-suppression exercises for either monocular or alternate suppression between January 2016 and December 2021 was conducted. Patients with esotropia less than 15 prism diopters (PD) and visual acuity ≥ 6/12 were included. Patients with previous intra-ocular surgery or less than three-month follow-up were excluded. Success was defined as the development of binocular single vision (BSV) for distance, near, or both (measured clinically with either the 4 prism base out test or Worth four dot test) and maintained at two consecutive visits. Qualified success was defined as the presence of diplopia response for both distance and near. Additionally, improvement in near stereo acuity was measured using the Stereo Fly test. Results: Eighteen patients with a mean age of 5.4 ± 1.38 years (range 3–8 years) at the time of initiation of exercises were included in the study. The male female ratio was 10:8. The mean best corrected visual acuity was 0.18 LogMAR unit(s) and the mean spherical equivalent was +3.8 ± 0.14 diopters (D). The etiology of the esotropia was fully accommodative refractive esotropia (8), microtropia (1), post–operative infantile esotropia (4), partially accommodative esotropia (1), and post-operative partially accommodative esotropia (4). Patients received either office-based, home-based, or both modes of treatment for an average duration of 4.8 months (range 3–8). After therapy, BSV was achieved for either distance or near in 66.6 % of patients (95 % CI = 40.03–93.31 %). Binocular single vision for both distance and near was seen in 50 % of children. Qualified success was observed in 38.46% of patients. Persistence of suppression was observed in one patient (5.5 %)... (AU)

Utility of retinoscopy to examine peripheral refraction

Purpose: This study explored whether retinoscopy (RET) provides comparable results of relative peripheral refraction (RPR) to open–field autorefractometry (AR) in myopic subjects.Methods: Peripheral refraction was measured in 20 myopic and 20 control adult subjects. Both central and peripheral refraction (20° nasal and temporal eccentricity) were measured using RET and open-field AR. Differences in the median central spherical equivalent (SE), median RPR, and median J45/J180 power vectors between the RET and AR techniques were analyzed. Moreover, Bland – Altman plots were used to assess the agreement between RET and AR methods for RPR measurements in MG. Results: For MG, the median RPR values were positive (hyperopic shift), and no significant differences were observed between the RET and AR techniques with respect to RPR measurement. In addition, we did not observe any significant differences in the RPR values between the nasal and temporal eccentricities for either the RET or AR technique for myopic subjects. There was also a significant correlation and agreement between the RET and AR technique for RPR measurements. With respect to central refraction, the median SE was slightly more positive for the RET than for the AR technique. Inside the CG, we also found significant correlation between the RET and AR technique for RPR measurements, and we observed a myopic shift in peripheral eccentricities. Conclusion: Our results show that retinoscopy may be a useful tool for objective measurements of RPR in myopic subjects and may be used interchangeably with the open-field AR method in everyday clinical practice. (AU)

Assessing the role of visual dysfunctions in the association between visual symptomatology and the use of digital devices / Evaluación del papel de las disfunciones visuales en la asociación entre la sintomatología visual y el uso de dispositivos digitales

Purpose: To evaluate the association between visual symptoms and use of digital devices considering the presence of visual dysfunctions. Methods: An optometric examination was conducted in a clinical sample of 346 patients to diagnose any type of visual anomaly. Visual symptoms were collected using the validated SQVD questionnaire. A threshold of 6 hours per day was used to quantify the effects of digital device usage and patients were divided into two groups: under and above of 35 years old. A multivariate logistic regression was employed to investigate the association between digital device use and symptoms, with visual dysfunctions considered as a confounding variable. Crude and the adjusted odds ratio (OR) were calculated for each variable. Results: 57.02 % of the subjects reported visual symptoms, and 65.02% exhibited some form of visual dysfunction. For patients under 35 years old, an association was found between having visual symptoms and digital device use (OR = 2.10, p = 0.01). However, after adjusting for visual dysfunctions, this association disappeared (OR = 1.44, p = 0.27) and the association was instead between symptoms and refractive dysfunction (OR = 6.52, p < 0.001), accommodative (OR = 10.47, p < 0.001), binocular (OR = 6.68, p < 0.001) and accommodative plus binocular dysfunctions (OR = 46.84, p < 0.001). Among patients over 35 years old, no association was found between symptoms and the use of digital devices (OR = 1.27, p = 0.49) but there was an association between symptoms and refractive dysfunction (OR = 3.54, p = 0.001). Conclusions: Visual symptoms are not dependent on the duration of digital device use but rather on the presence of any type of visual dysfunction: refractive, accommodative and/or binocular one, which should be diagnosed.(AU)

Study of stereopsis using a depth sensation detection platform equipped with computer vision technology (DALE3D) / Estudio de estereopsis mediante una plataforma de detección de sensaciones de profundidad equipada con tecnología de visión por ordenador (DALE3D)

Background and objectives: The invention described herein is a prototype based on computer vision technology that measures depth perception and is intended for the early examination of stereopsis. Materials and methods: The prototype (software and hardware) is a depth perception measurement system that consists on: (a) a screen showing stereoscopic models with a guide point that the subject must point to; (b) a camera capturing the distance between the screen and the subject's finger; and (c) a unit for recording, processing and storing the captured measurements. For test validation, the reproducibility and reliability of the platform were calculated by comparing results with standard stereoscopic tests. A demographic study of depth perception by subgroup analysis is shown. Subjective comparison of the different tests was carried out by means of a satisfaction survey. Results: We included 94 subjects, 25 children and 69 adults, with a mean age of 34.2 ± 18.9 years; 36.2 % were men and 63.8 % were women. The DALE3D platform obtained good repeatability with an interclass correlation coefficient (ICC) between 0.94 and 0.87, and coefficient of variation (CV) between 0.1 and 0.26. Threshold determining optimal and suboptimal results was calculated for Randot and DALE3D test. Spearman's correlation coefficient, between thresholds was not statistically significant (p value > 0.05). The test was considered more visually appealing and easier to use by the participants (90 % maximum score). Conclusions: The DALE3D platform is a potentially useful tool for measuring depth perception with optimal reproducibility rates. Its innovative design makes it a more intuitive tool for children than current stereoscopic tests. Nevertheless, further studies will be needed to assess whether the depth perception measured by the DALE3D platform is a sufficiently reliable parameter to assess stereopsis.(AU)

Binocular vision parameters and visual performance in bilateral keratoconus corrected with spectacles versus rigid gas-permeable contact lenses / Parámetros de visión binocular y rendimiento visual en queratocono bilateral corregido con gafas versus lentes de contacto rígidos permeables al gas

Purpose: To analyze binocular vision of individuals aged 18 to 35 years diagnosed with keratoconus, utilizing spectacles and rigid gas-permeable (RGP) contact lenses. Research was led by the Universidad Autónoma de Aguascalientes, México and Fundación Universitaria del Área Andina Pereira, Colombia. Methods: A single center, prospective non-randomized, comparative, interventional, open-label study, in which the differences in binocular vision performance with both spectacles and RGP contact lenses was carried out from December 2018 to December 2019. Sampling was performed according to consecutive cases with keratoconus that met the inclusion criteria until the proposed sample size was reached. Results: Rigid gas-permeable (RGP) contact lenses notably enhanced distance and near visual acuity in keratoconus patients compared to spectacles. Visual alignment analysis shows exophoria at both distances and is slightly higher with RGP contact lenses. The difference was statistically significant (p<0.05), with 82.5 % presenting compensated phoria with spectacles and pnly 42.50% with RGP contact lenses. Stereoscopic vision improved while wearing RGP contact lenses (42.59 %), although accommodation and accommodative flexibility remained within normal ranges. Conclusions: Patients with keratoconus fitted with RGP contact lenses have improved binocular vision skills such as visual acuity, stereopsis, and accommodative flexibility. However, even when the vergence and motor system is decompensated with respect to normal ranges, the range between break and recovery points for both fusional reserves and the near point of convergence (NPC) improves with the use of RGP contact lenses, giving indications of an adaptive condition of the motor system from the medium to the long term.(AU)

Ocular dominance-dependent binocular combination of monocular neuronal responses in macaque V1.

Primates rely on two eyes to perceive depth, while maintaining stable vision when either one eye or both eyes are open. Although psychophysical and modeling studies have investigated how monocular signals are combined to form binocular vision, the underlying neuronal mechanisms, particularly in V1 where most neurons exhibit binocularity with varying eye preferences, remain poorly understood. Here, we used two-photon calcium imaging to compare the monocular and binocular responses of thousands of simultaneously recorded V1 superficial-layer neurons in three awake macaques. During monocular stimulation, neurons preferring the stimulated eye exhibited significantly stronger responses compared to those preferring both eyes. However, during binocular stimulation, the responses of neurons preferring either eye were suppressed on the average, while those preferring both eyes were enhanced, resulting in similar neuronal responses irrespective of their eye preferences, and an overall response level similar to that with monocular viewing. A neuronally realistic model of binocular combination, which incorporates ocular dominance-dependent divisive interocular inhibition and binocular summation, is proposed to account for these findings.

Quantifying the Relationship Between Unilateral Induced Metamorphopsia and Stereopsis Impairment.

Purpose: To investigate the relationship between unilateral metamorphopsia, characterized by visual distortions in one eye, and impaired stereopsis. Methods: Utilizing both near and distance measurements through advanced testing systems, including 4K smartphones and an active shutter three-dimensional system, we simulated varying degrees of unilateral metamorphopsia in 30 healthy young adults aged between 21 and 29 years. Two types of contour-based stereotest symbols, lines and squares, were developed. Distortions were classified into six distinct patterns, each further divided into eight grades of severity. Participants were tasked with identifying visual targets, and their stereothresholds were determined under different conditions of induced distortion. Stereopsis was measured within a range of 2.9 to 1.0 log arcsec, at 0.2 log arcsec intervals. Stereopsis changes under different distortion scenarios were analyzed using the generalized estimating equations, with a sequential Bonferroni adjustment applied for pairwise comparisons. Results: A direct and quantifiable correlation was observed between the severity of metamorphopsia and reductions in stereopsis. As the degree of visual distortion increased, notably in both frequency and amplitude, there was a corresponding decline in stereopsis. This relationship held true in both near and distance measurements of stereopsis. Statistical analyses further reinforced these findings, highlighting a significant detrimental effect of distortion components on stereoacuity. Conclusions: The findings highlight the clinical significance of understanding the interplay between unilateral metamorphopsia and stereopsis. Early interventions in conditions leading to metamorphopsia might be critical to maintaining optimal stereopsis.

Peripheral Binocular Imbalance in Anisometropic and Strabismic Amblyopia.

Purpose: Individuals with amblyopia experience central vision deficits, including loss of visual acuity, binocular vision, and stereopsis. In this study, we examine the differences in peripheral binocular imbalance in children with anisometropic amblyopia, strabismic amblyopia, and typical binocular vision to determine if there are systematic patterns of deficits across the visual field. Methods: This prospective cohort study recruited 12 participants with anisometropic amblyopia, 10 with strabismic amblyopia, and 10 typically sighted controls (age range, 5-18 years). Binocular imbalance was tested at 0°, 4°, and 8° eccentricities (4 angular locations each) using band-pass filtered Auckland optotypes (5 cycles per optotype) dichoptically presented with differing contrast to each eye. The interocular contrast ratio was adjusted until the participant reported each optotype with equal frequency. Results: Participants with anisometropic and strabismic amblyopia had a more balanced contrast ratio, or decreased binocular imbalance, at 4° and 8° eccentricities as compared with central vision. Participants with strabismic amblyopia had significantly more binocular imbalance in the periphery as compared with individuals with anisometropic amblyopia or controls. A linear mixed effects model showed a main effect for strabismic amblyopia and eccentricity on binocular imbalance across the visual field. Conclusions: There is evidence of decreased binocularity deficits, or interocular suppression, in the periphery in anisometropic and strabismic amblyopia as compared with controls. Notably, those with strabismic amblyopia exhibited more significant peripheral binocular imbalance. These variations in binocularity across the visual field among different amblyopia subtypes may necessitate tailored approaches for dichoptic treatment.

Home vision therapy and prism prescription in presbyopic persons with convergence insufficiency: study protocol for a randomized controlled trial.

BACKGROUND: Convergence insufficiency is a common issue in the field of binocular vision. Various treatment options have been suggested for managing this condition, but their efficacy in individuals with presbyopia remains unclear. The objective of this study is to compare the effectiveness of home-based vision therapy and prism prescription, in presbyopic patients with convergence insufficiency. METHODS/DESIGN: It is a randomized, prospective, double-blind clinical trial, with total of 150 participants randomly assigned to the three groups. The Control Group will receive a new near glasses as a conventional prescription, along with aimless and random eye movement exercises that do not have any convergence or accommodation effects. The Home Vision Therapy Group will receive new near glasses with accommodative and convergence eye exercises. The Prism Group will receive a near prismatic glasses prescribed using the Sheard's criterion. All treatments will be administered for a period of 2 months, and measurements of the modified convergence insufficiency symptoms survey (CISS), near point convergence, near phoria, and positive fusional vergence will be taken at baseline, one month later, and at the end of the treatment. DISCUSSION: We aim to identify which component - either the prism prescription or the home vision therapy - is more effective in improving binocular abilities and reducing patients' symptom scores. TRIAL REGISTRATION: ClinicalTrials.gov NCT05311917 with last update on 04/22/2023.

Evaluation of objective and subjective binocular ocular refraction with looking in type.

BACKGROUND: This study aimed to compare the results of the Chronos binocular/monocular refraction system, that measures objective and subjective ocular refraction in one unit, to objective findings obtained from a conventional autorefractometer and a conventional subjective ocular refraction using a trial-frame in real space. METHODS: Twenty-eight healthy volunteers (21.2 ± 1.5 years old) were included in this study. Objective ocular refraction was measured using two tests: the Chronos binocular/monocular refraction system under binocular conditions and a conventional autorefractometer under monocular conditions. Subjective ocular refraction was measured using three tests: Chronos binocular/monocular refraction system under binocular, monocular conditions, and trial-frame in the real space under monocular conditions. The measurement distance was set to 5.0 m for each test. All ocular refractions were converted into spherical equivalents (SEs). RESULTS: The objective SE was significantly more negative with Chronos binocular/monocular refraction system under binocular condition (- 4.08 ± 2.76 D) than with the conventional autorefractometer under monocular condition (- 3.85 ± 2.66 D) (P = 0.002). Although, the subjective SE was significantly more negative with Chronos binocular/monocular refraction system under binocular condition (- 3.55 ± 2.67 D) than with the trial-frame in the real space under monocular condition (- 3.33 ± 2.75 D) (P = 0.002), Chronos binocular/monocular refraction system under monocular condition (- 3.17 ± 2.57 D) was not significantly different from that in trial-frame in real space under monocular condition (P = 0.33). CONCLUSION: These findings suggest that the Chronos binocular/monocular refraction system, which can complete both objective and subjective ocular refraction tests in a single unit, is suitable for screening ocular refraction, although it produces slightly more myopic results. Furthermore, subjective ocular refraction testing accuracy in Chronos binocular/monocular refraction system can be equivalent to trial-frame in real-space testing by switching from binocular to monocular condition.

Visual Outcomes According to Age After Bilateral Implantation of Trifocal Intraocular Lenses.

PURPOSE: To investigate the effect of age on visual outcomes after the bilateral implantation of trifocal intraocular lenses (IOLs). METHODS: A total of 290 patients (580 eyes) who underwent bilateral implantation of a trifocal IOL were enrolled in this retrospective case-control study. Patients were divided into five age groups: 45 to 49, 50 to 54, 55 to 59, 60 to 64, and 65 years and older. Postoperative monocular uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively), uncorrected near visual acuity (UNVA), binocular distance-corrected defocus curve, spectacle dependence for near and distance vision, and patient satisfaction scores were compared among the five groups. RESULTS: The 45 to 49 years group had significantly better mean UDVA (0.02 ± 0.05 logMAR) and UNVA (0.02 ± 0.04 logMAR) than the 65 years and older group (0.06 ± 0.09 and 0.09 ± 0.09 logMAR; P = .029 and P < .001; respectively). However, no significant differences were observed in the mean CDVA among the groups. Binocular visual performance of the 45 to 49 years group was better than that of the 65 years and older age group at defocuses of +1.00, +0.50, -1.00, and -3.00 D. No significant differences were observed in spectacle dependence for near and distance vision or in patient satisfaction scores among the five groups. CONCLUSIONS: Bilateral implantation of trifocal IOLs can provide excellent near and distance vision in both young and older patients. However, UDVA and UNVA revealed considerably worse results in the older group, although no significant difference was observed in CDVA and postoperative refractive errors by age. [J Refract Surg. 2024;40(4):e270-e277.].

Short communication: Binocular rivalry dynamics during locomotion.

Locomotion has been shown to impact aspects of visual processing in both humans and animal models. In the current study, we assess the impact of locomotion on the dynamics of binocular rivalry. We presented orthogonal gratings, one contrast-modulating at 0.8 Hz (matching average step frequency) and the other at 3.2 Hz, to participants using a virtual reality headset. We compared two conditions: stationary and walking. We continuously monitored participants' foot position using tracking devices to measure the step cycle. During the walking condition, participants viewed the rivaling gratings for 60-second trials while walking on a circular path in a virtual reality environment. During the stationary condition, observers viewed the same stimuli and environment while standing still. The task was to continuously indicate the dominant percept via button press using handheld controllers. We found no significant differences between walking and standing for normalized dominance duration distributions, mean normalized dominance distributions, mean alternation rates, or mean fitted frequencies. Although our findings do not align with prior research highlighting distinctions in normalized dominance distributions between walking and standing, our study contributes unique evidence indicating that alternation rates vary across the step cycle. Specifically, we observed that the number of alternations is at its lowest during toe-off phases and reaches its peak at heel strike. This novel insight enhances our understanding of the dynamic nature of alternation patterns throughout the step cycle.

Scotopic and Photopic Conventional Visual Acuity and Hyperacuity - Binocular Summation.

Purpose: The purpose of this study was to determine and compare binocular summation (BiS) of conventional visual acuity (cVA) versus hyperacuity (hVA) for photopic and scotopic luminance conditions as a potential biomarker to assess the outcome of interventions on binocular function. Methods: Sixteen young adults (age range [years] = 21-31; 8 women; cVA logMAR < 0.0) participated in this study. The Freiburg Visual Acuity Test (FrACT) was used for VA testing and retested on another day. Both cVA and hVA were determined for dark grey optotypes on light grey background. Participants underwent 40 minutes of dark adaptation prior to scotopic VA testing. Binocular and monocular VA testing was performed. The eye with better VA over the 2 days of testing was selected, the BiS was quantified (binocular VA - better monocular VA) and repeated measures ANOVAs were performed. Results: Binocular VA exceeded monocular VA for all luminance conditions, VA-types, and sessions. We report BiS estimates for photopic and scotopic cVA and hVA, (logMAR BiS ± SEM [decimal BiS]): photopic = -0.01 ± 0.01 [1.03] and -0.06 ± 0.03 [1.15]; and scotopic = -0.05 ± 0.01 [1.12] and -0.11 ± 0.04 [1.28], respectively). Improvement for binocular vision estimates ranged from 0.01 to 0.11 logMAR. A repeated-measures ANOVA (RM ANOVA) did not reveal significant effects of LUMINANCE or VA TYPE on BiS, albeit a trend for strongest BiS for scotopic hVA (15% vs. 28%, photopic versus scotopic, respectively) and weakest for photopic cVA (3% vs. 12%, photopic versus scotopic conditions, respectively). Conclusions: Our results indicate that BiS of VA is relevant to scotopic and photopic hVA and cVA. It appears therefore a plausible candidate biomarker to assess the outcome of retinal therapies restoring rod or cone function on binocular vision. Translational Relevance: Binocular summation of visual acuity might serve as a clinical biomarker to monitor therapy outcome on binocular rod and cone-mediated vision.

Comparison of Two Presbyopia-Correcting Trifocal Intraocular Lenses: A Prospective Study.

Objectives: To evaluate the clinical results of a new trifocal intraocular lens (IOL) with sinusoidal design by comparing with a traditional trifocal IOL. Materials and Methods: A total of 79 patients undergoing uneventful microincisional cataract surgery with bilateral implantation of one of two types of trifocal IOLs, the Acriva Trinova IOL (VSY) or Acrysof IQ PanOptix IOL (Alcon), were enrolled in this prospective study. Visual and refractive outcomes, contrast sensitivity (CS), and defocus curve were assessed at 3 months after surgery. Patient satisfaction and incidence of photic phenomena were also evaluated. Results: The number of patients/eyes were 48/96 in the Trinova group and 31/62 in the PanOptix group. There were no significant differences between the groups for monocular and binocular corrected/uncorrected distance or intermediate (at 60 cm) and near visual acuities (VA) postoperatively. The Trinova group had statistically significantly better intermediate VA at 80 cm than the PanOptix group (p<0.05). The CS results of both groups were within the normal limits. In the binocular defocus curve of both IOLs, we observed a peak of good VA at 0.0 diopters defocus and a useful wide range for intermediate distances. The incidence of photic phenomena in the Trinova group was lower at postoperative 1 month (p<0.05) but this difference disappeared at 3 months. A total of 47 patients (97.9%) in the Trinova group and 30 patients (96.7%) in the PanOptix group stated that they would recommend the same IOL. Conclusion: Both trifocal IOLs provide good visual quality outcomes and patient satisfaction.

[The timing and challenges of early intervention for infantile esotropia].

Infantile esotropia is a common ophthalmic disease in children. A lot of clinical and basic research evidence suggests that early surgery enhances sensory and ocular motor development. However, the proper timing of surgery has been debated for decades. In addition, there is more likely instability of deviation in the preoperative evaluation of infants, and even if the patient achieved alignment after surgery, the defects in binocular vision may accompany for a lifetime. This article analyzes the difficulties and key points of early intervention for infantile esotropia, aiming to provide scientific ideas for the early treatment of children with infantile esotropia in China.

Comparison of Early Vision Quality of SBL-2 and SBL-3 Segmented Refractive Lens.

PURPOSE: To compare objective quality of vision in patients undergoing phacoemulsification with implantation of a bilateral segmented multifocal intraocular lens (SMIOL). METHODS: A retro-prospective study included 110 eyes of 55 patients who underwent cataract surgery with bilateral SMIOL implantation. Patients were divided according to the type of implanted intraocular lens into group 1 (SBL-2, 62 eyes) and group 2 (SBL-3, 48 eyes). Postoperatively, monocular and binocular uncorrected distance visual acuity (UCDVA), corrected distance visual acuity (BCDVA), uncorrected intermediate visual acuity (UCIVA, at 66 cm), uncorrected near visual acuity (UCNVA, at 40 cm), corrected near visual acuity (BCNVA) and defocus curve were measured and evaluated. The follow-up period was 6 months. RESULTS: Mean UCDVA in group 1 (SBL-2) was 0.010 ±0.15 LogMAR monocularly, 0.01 ±0.10 LogMAR binocularly, and in group 2 (SBL-3) was 0.02 ±0.11 LogMAR monocularly and -0.07 ±0.09 LogMAR binocularly. Binocular defocus curves showed that the SBL-3 group performed better than the SBL-2 lens at a vergence of -1.50 D corresponding to 66 cm (center distance), averaging 0.03 ±0.11 LogMAR, while the SBL-2 group averaged 0.12 ±0.14 LogMAR (p = 0.01). The -2.50 D vergence characterizing near vision (40 cm) was achieved by the SBL-2 lens in our study at 0.33 ±0.15 LogMAR and by the SBL-3 lens at 0.00 ±0.11 LogMAR (p = 0.00). CONCLUSION: Both SMIOLs provided very good vision at all tested distances 6 months postoperatively. The SBL-2 lens performed better in UCIVA, while the SBL-3 lens excelled in UCDVA and UCNVA.

Visual outcomes after cataract surgery in monocular compared to binocular patients: a case-control study.

PURPOSE: We aimed to identify ocular comorbidities and reasons of blindness in monocular patients and to compare visual outcomes of cataract surgery between monocular and binocular patients. METHODS: A single-center case-control study was conducted between November 2011 and May 2019 to compare consecutive series of patients needing cataract surgery in Strasbourg University Hospitals, France. Cases were patients with permanent monocular vision loss. Controls were binocularly sighted patients. All patients underwent cataract surgery using phacoemulsification technique. Chart analysis included demographic data, medical history, and surgical determinants data. Student's t tests and Fisher's exact tests were the main methods used for statistical analysis. RESULTS: Each group included 80 patients. The mean age at the time of surgery was significantly higher in monocular than binocular patients (77 vs. 71 years, p < 0.001). Thirty-two monocular patients (40%) had ocular comorbidities, compared to only 19 (23%) in the control group (p < 0.05). The leading cause of monocular status was amblyopia caused by strabismus (22 patients, 27.5%). Age-related macular degeneration, open-angle glaucoma, and diabetic retinopathy were the three main ocular comorbidities that were observed in the monocular group. Monocular patients had significantly lower visual acuity than the control group (p < 0.01) before and after cataract surgery. Conversely, improvement in visual acuity after surgery was not statistically different between groups (p = 0.054). There was no statistically significant difference in the rate of surgical complications between groups (p = 0.622). CONCLUSIONS: This study illustrates that cataract surgery in monocular patients is not more complicated than in binocular patients, but that it is significantly delayed.

Surgical management of oculomotor nerve palsy: a comparison of lateral rectus deactivation combined with either medial rectus resection or medial rectus fixation to the medial palpebral ligament.

PURPOSE: To analyze and compare the outcome of two different surgical procedures in patients with complete oculomotor nerve palsy with large-angle exotropia. METHODS: The medical records of patients with total oculomotor nerve palsy and large-angle exotropia operated on at a single center from January 2006 to June 2020 were reviewed retrospectively. One group underwent lateral rectus deactivation with medial rectus resection (resection group); the other group underwent lateral rectus deactivation with medial rectus fixation to the medial palpebral ligament (fixation group). Surgical outcomes on the first postoperative day and at 6 months postoperatively were analyzed, including alignment and postoperative complications. All statistical analyses were performed using STATA version 14. A P value of <0.05 was considered significant. RESULTS: A total of 35 patients were included. There was a trend toward greater surgical success in the fixation group (93%) than in the resection group (65%), but these results were not statistically significant. Postoperative exotropic drifts were noted in both the procedures but tended to be more with patients in the resection group. Postoperative complications were noted only in the fixation group. CONCLUSIONS: Lateral rectus deactivation with medial rectus fixation to the medial palpebral ligament requires more time and greater surgical expertise but appears to better prevent postoperative exotropic drift compared with lateral rectus deactivation combined with medial rectus resection.

Absolute and relative disparity mechanisms revealed by an equivalent noise analysis.

The precision of stereopsis and vergence are ultimately limited by internal binocular disparity noise. Here we propose an equivalent noise model with both global and local internal disparity noises to provide a unified explanation of both absolute and relative disparity thresholds. To test this model, we developed a psychophysical procedure to measure the equivalent internal disparity noise by adding external disparity noise to random-Gabor-patch stereograms. We used the method of constant stimuli to measure the minimum and maximum disparity thresholds (Dmin and Dmax) for both absolute and relative disparity. Consistent with previous studies, we found that Dmin thresholds are substantially worse for absolute disparity than for relative disparity. We tested three relative disparity mechanisms: (1) the difference between the monocular separations of targets projecting to the two eyes; (2) the direct measurement of relative disparity; and (3) the difference of absolute disparities of targets. Computing the difference of absolute disparities when detecting relative disparity, Mechanism 3 cancels global noise, resulting in a much lower relative Dmin threshold, and provides a reasonable fit to the experimental data. We also found that the presence of as much as 2400 arcsec of external disparity noise does not appear to affect the Dmax threshold. This observation suggests that Dmax is implicated in a mechanism that disregards the disparity variance of individual items, relying instead on the average disparity across all items, supporting the depth model proposed in our previous study (Ding & Levi, 2021), which posits distinct mechanisms governing Dmin and Dmax thresholds.

Transient binocular vision loss and pain insensitivity in Klippel-Feil syndrome: a case report.

BACKGROUND: Klippel-Feil syndrome is a rare congenital bone disorder characterized by an abnormal fusion of two or more cervical spine vertebrae. Individuals with Klippel-Feil syndrome exhibit diverse clinical manifestations, including skeletal irregularities, visual and hearing impairments, orofacial anomalies, and anomalies in various internal organs, such as the heart, kidneys, genitourinary system, and nervous system. CASE PRESENTATION: This case report describes a 12-year-old Pashtun female patient who presented with acute bilateral visual loss. The patient had Klippel-Feil syndrome, with the typical clinical triad symptoms of Klippel-Feil syndrome, along with Sprengel's deformity. She also exhibited generalized hypoalgesia, which had previously resulted in widespread burn-related injuries. Upon examination, bilateral optic disc swelling was observed, but intracranial pressure was found to be normal. Extensive investigations yielded normal results, except for hypocalcemia and low vitamin D levels, while parathyroid function remained within the normal range. Visual acuity improved following 2 months of calcium and vitamin D supplementation, suggesting that the visual loss and optic nerve swelling were attributed to hypocalcemia. Given the normal parathyroid function, it is possible that hypocalcemia resulted from low vitamin D levels, which can occur after severe burn scarring. Furthermore, the patient received a provisional diagnosis of congenital insensitivity to pain on the basis of the detailed medical history and the findings of severe and widespread loss of the ability to perceive painful stimuli, as well as impaired temperature sensation. However, due to limitations in genetic testing, confirmation of the congenital insensitivity to pain diagnosis could not be obtained. CONCLUSION: This case highlights a rare presentation of transient binocular vision loss and pain insensitivity in a patient with Klippel-Feil syndrome, emphasizing the importance of considering unusual associations in symptom interpretation.