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.

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.

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.

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.].

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.

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.

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.

[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.

Six-month binocular stereopsis recovery and its influencing factors in children with intermittent exotropia.

OBJECTIVE: To investigate the recovery of binocular stereopsis recovery and its influencing factors in children with intermittent exotropia after successful correction of eye position. METHODS: Prospective clinical study. A total of 178 patients, aged 9 ∼ 14 (10.8 ± 1.7) years, who were successfully corrected after intermittent exotropia surgery at the Beijing Tongren Hospital Affiliated to Capital Medical University from October 2023 to September 2023 were collected, the follow-up duration was six-month or longer. Paired t test, Pearson correlation analysis and multivariable linear regression analysis were used to probe preoperative clinical features that may predict the stereopsis six months after surgery. RESULTS: Six months after surgery, the angle of deviation of the patients met the orthotopic standard, and there was significant difference compared with that before surgery (distant: -2.7△±3.2△ vs. -30.5△±8.4△, t=-25.3, P < 0.001. Near:-3.7△±4.1△ vs. -33.7△±8.0△, t=-26.1, P < 0.001). Distant stereopsis (3.0 ± 0.6 vs. 3.9 ± 0.4, t = 4.9, P < 0.05) and near stereopsis (2.3 ± 0.5 vs. 2.6 ± 0.4, t = 3.8, P < 0.05) were both significantly improved compared with that of before surgery. 17% and 22% patients rebuilt normal distant stereopsis and normal near stereopsis, respectively. Preoperative distant stereopsis (r=-0.26, P = 0.004) and near stereopsis (r=-0.23, P = 0.011) was significantly negatively correlated with convergence reserve. Multivariable analysis showed that patients' age (ß = 0.003, p = 0.037), anisometropia (ß = 0.015, p = 0.043), and preoperative distant stereopsis (ß = 0.456, p < 0.001) were significantly associated with postoperative distant stereopsis. Patients' age (ß = 0.005, p = 0.044), anisometropia (ß = 0.127, p = 0.034), angle of deviation (ß=-0.230, p = 0.020), and preoperative near stereopsis (ß = 0.136, p < 0.001) were significantly associated with postoperative near stereopsis. CONCLUSION: IXT patients could get eye position fixed after surgery, about 20% patients benefited from stereopsis improvement. Patient's age, binocular anisometropia, angle of deviation and preoperative stereopsis were independent factors influencing postoperative stereopsis.

An investigation into the correlation between visual performance in simulated complex environments and academic attainment among primary school students.

Traditional vision screenings in schools are limited to simple visual tasks, yet students in their daily learning face more complex visual environments. Binocular rivalry tasks can partially simulate the visual challenges of real visual environments and activate advanced visual processing mechanisms that simple visual tasks cannot. Therefore, by superimposing binocular rivalry-state tasks onto simple visual tasks, we have developed an innovative vision screening program to rapidly and extensively assess students' visual performance in complex environments. This is a cross-sectional study in which we investigated the performance of 1126 grade 1-6 students from a primary school in Wuxi, China, in rivalry-state stereoscopic vision tasks. The correlation between the screening results of 1044 students and their academic achievements was also statistically analyzed. The study results revealed pass rates of 53.5-60.5% across various visual tests. Specifically, for first-grade students, there was a statistically significant difference in standardized Chinese scores between the group that failed and the group that passed the rivalry-state stereoscopic vision test (- 0.49 ± 3.42 vs. 0.22 ± 0.58, t = - 2.081, P = 0.04). This result underscores the importance of focusing on the visual adaptability of first graders in complex environments.Trail registration: Ethics Committee of Affiliated Children's Hospital of Jiangnan University-Certificate number: WXCH2022-04-027.

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.

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.

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.

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.

Effect of refractive errors on the results of botulinum neurotoxin administration in patients with infantile esotropia.

PURPOSE: To investigate the effect of refractive errors on the results of patients followed up with infantile esotropia (IE) and treated with botulinum neurotoxin (BNT) injection. METHODS: The files of patients with IE who presented to the ophthalmology pediatric ophthalmology unit and underwent BNT injection into both medial rectus muscles between 2019 and 2021 were reviewed retrospectively. Sixty eyes of 30 patients were included in the study. Patients with additional systemic or ocular diseases and those with a history of ocular surgery were excluded. Distance and near deviations were measured (with the prism cover test or Krimsky method) before and at the first, third, and sixth months after BNT injection. RESULTS: In Group 1 (n = 20) with a spherical equivalent of + 2.0 diopters (D) or less, the mean near and distance deviation value was both 36.8 ± 12.7 prism diopter (PD) before injection. In Group 2 (n = 10) with a spherical equivalent of above + 2.0 D, the near deviation was measured as 35.0 ± 7.1 PD and distance deviation as 31.8 ± 7.9. At six months after BNT injection, the near and distance deviation values were 20.6 ± 12.3 and 20.6 ± 11.6 PD, respectively in Group 1 and 10.1 ± 10.3 and 8.8 ± 10.8 PD, respectively in Group 2. The change in deviation did not statistically significantly differ between the groups (p > 0.05), but the distance and near deviation values were lower in Group 2 at sixth months after BNT injection. CONCLUSIONS: BNT injection is a preferred method in IE. Higher hypermetropic values seem to increase the success of BNT injection.

Long-term Results after Bilateral Implantation of Extended Depth of Focus Intraocular Lenses with Mini-Monovision.

PURPOSE: To assess long-term clinical results following bilateral Tecnis Symfony ZXR00 intraocular lens implantation with mini-monovision. METHODS: The medical records of cataract patients who underwent bilateral implantation of ZXR00 with intended mini-monovision (target refraction of -0.3 diopters [D] in dominant eye and -0.6 D in nondominant eye) between April 2019 and March 2021 were assessed. Postoperative uncorrected distance visual acuity (UDVA), corrected distance VA (CDVA), uncorrected intermediate VA (UIVA), uncorrected near VA (UNVA), and rate of spectacle dependence for near distance were investigated at 3 months and 2 years after surgery. RESULTS: This study included 61 patients (122 eyes) with average age of 61.8 ± 7.7 years. At 2 years postoperatively, binocular logarithm of the minimum angle of resolution UDVA, UIVA, UNVA, and CDVA were 0.086 ± 0.094, 0.056 ± 0.041, 0.140 ± 0.045, and 0.012 ± 0.024, respectively. The monocular manifest refraction spherical equivalent was -0.31 ± 0.38 in the dominant eye and -0.53 ± 0.47 in the nondominant eye at 3 months postoperatively, and -0.38 ± 0.43 in the dominant eye and -0.61 ± 0.54 in the nondominant eye at 2 years postoperatively. Eight out of 61 patients (13.1%) needed glasses 3 months after surgery, and nine out of 61 patients (14.8%) needed glasses 2 years after surgery. CONCLUSIONS: The bilateral implantation of ZXR00s with mini-monovision allows for a good VA at wide range of distance from far to near, thereby resulting in high rate of spectacle independence. These results have held up well even after 2 years after surgery.

Changes in ocular extorsion after horizontal muscle surgery in patients with intermittent exotropia coexisting with hypertropia and mild inferior oblique overaction.

PURPOSE: To investigate changes in vertical strabismus and extorsion in patients with intermittent exotropia and mild unilateral inferior oblique muscle overaction (IOOA) who underwent horizontal muscle surgery without vertical or oblique muscle surgery. METHODS: The medical records of 41 patients were retrospectively analyzed. The patients were followed up for at least 6 months after surgery. Fundus photography was performed before and after surgery, and the sum of the angles of torsion in both eyes was used to measure changes in extorsion using ImageJ software. The enrolled patients were divided into two groups according to the degree of IOOA: patients with grade 1 IOOA were placed in +1 IOOA group and those with grade 2 IOOA in +2 IOOA group. The pre- and postoperative angles of horizontal and vertical strabismus and extorsion were compared between the two groups. RESULTS: The +1 IOOA and +2 IOOA groups included 24 and 17 patients, respectively. The angle of preoperative exotropia did not differ significantly: 25.54 ± 5.68 prism diopters (PD) and 25.65 ± 8.11 PD in the +1 IOOA and +2 IOOA groups, respectively. In the +1 IOOA and +2 IOOA groups, hypertropia was 2.67 ± 1.52 PD and 2.82 ± 1.13 PD, respectively, and extorsion angles were 7.14 ± 2.77° and 7.94 ± 2.87°, respectively. As the IOOA degree increased, the extent of hypertropia and extorsion also increased. However, there were no significant differences between the two groups. Postoperative angles of hypertropia and extorsion significantly decreased in both groups (p < 0.001) after surgery. The degree of change in hypertropia and extorsion was not significantly different between the two groups (p = 0.563 and p = 0.354, respectively). CONCLUSIONS: Hypertropia and extorsion improved significantly after horizontal muscle surgery in patients with mild unilateral IOOA and intermittent exotropia. There was no significant difference in the improvement in hypertropia or extorsion between IOOA grades I and II.

Effects of binocular cue availability on leaping performance in Cheirogaleus medius: implications for primate origins.

Multiple competing hypotheses attribute the evolution of the suite of traits that distinguish primates from their closest relatives, including forward-facing eyes, which create a wide field of binocular vision, to specific behavioral and ecological factors. The grasp-leaping hypothesis suggests that the evolution of these traits in basal primates was driven by the demands of a form of leaping locomotion unique to primates. Whether the grasp-leaping hypothesis provides a viable mechanism for the evolution of primates' forward-facing eyes remains untested. To determine whether grasp-leaping locomotion may have contributed to driving the evolution of primates' forward-facing eyes, the importance of vision within the binocular field for this type of leaping was evaluated experimentally in Cheirogaleus medius, one of the cheirogaleid primate species considered reasonable living analogs of the earliest primates. Availability of binocular visual cues was experimentally restricted using a head-mounted blinder that narrowed the binocular visual field without altering the total visual field. Animals altered their launch behavior, reduced their horizontal leap speed, and were significantly more likely to select paths that offered the shortest available leaps when their binocular field was restricted. Restriction of binocular cue availability also significantly increased the probability of adverse landings even when statistically controlling for potentially confounding variables such as leap distance, horizontal leap speed, learning effects, etc. These results suggest a functional mechanism by which selection for improved grasp-leaping could also have contributed to the evolution of forward-facing eyes in the earliest crown primates.

The incidence, clinical features, and management of essential infantile esotropia in the United Kingdom. A British Ophthalmology Surveillance Unit (BOSU) study.

BACKGROUND/OBJECTIVES: A national study was undertaken through the British ophthalmology surveillance unit (BOSU) to determine the incidence, presenting features and management of essential infantile esotropia (EIE) in the UK. METHODS: Data from a prospective national observational study of newly diagnosed EIE presenting to clinicians in the United Kingdom over a 12-month period were collected. Cases with a confirmed diagnosis by a clinician of a constant, non-accommodative esotropia ≥20 prism dioptres (PD), presenting at ≤12 months, with no neurological or ocular abnormalities were identified through BOSU. Follow-up data were collected at 12 months. RESULTS: A total of 57 cases were reported giving an incidence of EIE of 1 in 12,828 live births. The mean age of diagnosis and intervention were 7.05 ± 2.6 months (range 2-12) and 14.7 ± 4.9 months (range 6.5-28.1), respectively. Management was surgical in 59.6%, botulinum toxin alone in 22.8%, and 17.5% were observed. The preoperative angle of esotropia was smaller in the observation group (P = 0.04). The postoperative angle of esotropia was not statistically significant between botulinum toxin or surgery (P = 0.3), although the age of intervention was earlier in the botulinum group (P = 0.007). Early intervention (before 12 months of age) did not influence the post-intervention motor outcomes between 0 and 10 prism dioptres of esotropia (P = 0.78). CONCLUSIONS: The incidence of EIE in the UK is considerably lower than reported in other population-based studies. The preferred method of treatment was surgical with earlier intervention in those treated with botulinum toxin. An early age of intervention (<12 months) did not influence motor outcomes.