An Eye-Tracking-Based Dichoptic Home Treatment for Amblyopia: A Multicenter Randomized Clinical Trial.

PURPOSE: Comparing visual outcomes after use of a novel binocular eye-tracking-based home treatment (CureSight; NovaSight, Ltd) with patching. DESIGN: Prospective, multicenter, randomized, masked, controlled, noninferiority pivotal trial. PARTICIPANTS: One hundred three children 4 to < 9 years with anisometropic, small-angle strabismic or mixed-mechanism amblyopia were randomized 1:1 to either CureSight treatment or patching. METHODS: The CureSight treatment uses combined anaglyph glasses and an eye tracker to induce real-time blur around the fellow eye fovea in dichoptic streamed video content. Participants used the device for 90 minutes/day, 5 days/week for 16 weeks (120 hours). The patching group received 2 hours of patching 7 days/week (224 hours). The prespecified noninferiority margin was 1 line. MAIN OUTCOME MEASURES: The primary outcome was the improvement in the amblyopic eye visual acuity (VA), modeled with a repeated measures analysis of covariance. Secondary outcomes included stereoacuity, binocular VA, and treatment adherence rates, analyzed by a 1-sample Wilcoxon test within each group and a 2-sample Wilcoxon test comparing groups. Safety outcomes included the frequency and severity of study-related adverse events (AEs). RESULTS: CureSight group VA improvement was found to be noninferior to patching group improvement (0.28 ± 0.13 logarithm of the minimum angle of resolution [logMAR] [P < 0.0001] and 0.23 ± 0.14 logMAR [P < 0.0001], respectively; 90% confidence interval [CI] of difference, -0.008 to 0.076). Stereoacuity improvement of 0.40 log arcseconds (P < 0.0001) and improved binocular VA (0.13 logMAR; P < 0.0001) were observed in the binocular treatment group, with similar improvements in the patching group in stereoacuity (0.40 log arcseconds; P < 0.0001) and binocular VA (0.09 logMAR; P < 0.0001), with no significant difference between improvements in the 2 groups in either stereoacuity (difference, 0; 95% CI, -0.27 to -0.27; P = 0.76) or binocular VA (difference, 0.041; 95% CI, -0.002 to 0.085; P = 0.07). The binocular treatment group had a significantly higher adherence than the patching group (91% vs. 83%; 95% CI, -4.0% to 21%; P = 0.011). No serious AEs were found. CONCLUSIONS: Binocular treatment was well tolerated and noninferior to patching in amblyopic children 4 to < 9 years of age. High adherence may provide an alternative treatment option for amblyopia. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

The benefits, risks, and efficacy of strabismus surgery in adults.

Strabismus surgery in adults achieves satisfactory alignment with one operation in approximately 80% of patients, depending on the specific nature of the problem. Risks of adult strabismus surgery are relatively low, and serious complications are anecdotal and rare. Even if the strabismus has been long-standing, most adults will experience some improvement in binocular function after strabismus surgery. Consequently, adult strabismus surgery should not be considered merely cosmetic in most cases. In esotropic patients, this improvement typically takes the form of an expansion of binocular visual fields; however, some patients may also regain stereopsis. There are many psychosocial benefits to adult strabismus surgery. This is reflected in the finding that the majority of adults surveyed with strabismus would trade a portion of their life expectancy to be rid of their strabismus.

Binocular Home Treatment for Amblyopia: Gains Stable for One Year.

PURPOSE: To report the long-term outcomes of a noninferiority randomized controlled trial (RCT) with a binocular eye-tracking-based home treatment (CureSight; NovaSight, Ltd.) in patients with amblyopia. DESIGN: Prospective, multicenter, nonrandomized, long-term follow-up observational study of an RCT. METHODS: Forty-three children 4 to <9 years of age with anisometropic, small-angle strabismic, or mixed-mechanism amblyopia were initially treated for 16 weeks (NCT05185076) with CureSight. In this planned observational follow-up study, 38 patients with no additional amblyopia treatment were evaluated at 12 weeks post-treatment, and 27 were evaluated at 1-year post-treatment. The main outcome measures were visual acuity (VA), stereoacuity, and amblyopia recurrence at 12- and 52-week post-treatment. RESULTS: At 12-week post-treatment, improvement in amblyopic eye VA was maintained vs baseline (0.27 ± 0.14 logMAR, P< .0001), with no change vs the end-of-treatment visit (P > .05). At 1 year there was a partial reduction in the amblyopic eye VA gain of 0.085±0.1 logMAR compared to end-of-treatment (P = .001), but the residual gain of 0.20±0.14 logMAR compared to baseline was statistically significant (P < .0001). Gains in stereoacuity and binocular VA were maintained vs baseline at both 12-weeks and 1-year post-treatment (P < .0001), with no change vs end-of-treatment (P > .05). Amblyopia recurrence (a worsening of ≥2 logMAR levels compared with end-of-treatment) occurred in 2/38 patients at 12-weeks post-treatment (5.3%), and in 5/27 patients at 1-year post-treatment (20.4%). CONCLUSIONS: VA and stereopsis gains following binocular treatment with CureSight were maintained at 1 year without additional treatment.

High-adherence dichoptic treatment versus patching in anisometropic and small angle strabismus amblyopia: a randomized controlled trial.

PURPOSE: To compare the effectiveness and safety of a novel binocular eye-tracking-based-home-treatment (CureSight) to patching for the treatment of amblyopia. DESIGN: Prospective, masked, randomized controlled noninferiority trial. SETTING: Multicenter, multinational, home treatment. PARTICIPANTS: One hundred forty-nine children 4 to < 9 years with anisometropic, small-angle strabismic, or mixed-mechanism amblyopia were randomized to either binocular treatment (n=75) or patching (n=74). INTERVENTIONS: The binocular treatment group used the CureSight system for 90 min/day, 5 days/week for 16 weeks (120 hours). The patching group received 2-hour patching 7 days/week (224 hours). MAIN OUTCOME MEASURES: The primary outcome was the mean improvement from baseline in amblyopic eye visual acuity (VA) to week 16 in both study groups (non-inferiority of ≤0.10 logarithm of the minimum angle of resolution [logMAR]). Other outcomes included changes in stereoacuity and binocular VA from baseline to week 16. RESULTS: The mean improvement from baseline at week 16 in the binocular treatment group was noninferior to patching group improvement in the modified intent-to-treat (mITT) dataset (LS mean difference between groups in improvement from baseline: 0.034 logMAR (95% CI -0.009 to 0.076)). In the per-protocol (PP) dataset, the mean improvement from baseline at week 16 in the binocular treatment group was superior to patching group improvement (LS mean difference between groups in improvement from baseline: 0.05 logMAR ([95% CI; 0.007 to 0.097]). At week 16, both groups showed significant median improvement in stereoacuity, with no significant between-group difference in the magnitude of improvement in both the mITT and the PP datasets. Binocular VA was also improved in both groups (p<0.0001). Median adherence in the mITT binocular treatment group (94.0%) was also significantly higher than in the patching group (83.9%; p=0.0038). CONCLUSIONS: Binocular, eye-tracking-based amblyopia home treatment is at least as effective as patching.

Lateral Rectus Disabling and Simultaneous Modified Nishida Procedure for Exotropic Duane Retraction Syndrome.

Exotropic-Duane Syndrome (XT-DRS) is a congenital cranial nerve dysinnervation disorder characterized by exotropia, anomalous head posture (contralateral face turn), limited adduction, globe retraction, palpebral fissure narrowing, upshoot and downshoot in adduction, and varying levels of limitation of abduction. Patients with XT-DRS often have poor convergence because attempted convergence induces co-contraction of the lateral rectus muscle (LR) due to anomalous LR innervation. We describe two patients with XT-DRS who underwent simultaneous lateral rectus muscle (LR) disinsertion and periosteal fixation (LRDAPF) and modified Nishida procedure (MNP) and discuss their outcome. In one patient, we combined this procedure with a contralateral LR recession. Anomalous head posture, exotropia, globe retraction, and palpebral fissure narrowing were reduced. Upshoot and downshoot were also reduced. Convergence improved in both patients.

Modified Nishida Procedure Combined with Lateral Rectus Disabling for Duane Retraction Syndrome.

Duane retraction syndrome (DRS) is a complex congenital cranial dysinnervation disorder. The choice of surgical procedure in esotropic-DRS depends upon several factors that include: the amount of esotropia in the primary position, the presence and severity of palpebral fissure narrowing, globe retraction, presence of medial rectus muscle (MR) contracture, the likelihood of improving abduction, age of the patient, and the presence of binocularity and stereopsis. In the presence of MR contracture, MR recession is performed either alone (unilaterally or bilaterally) or in conjunction with Y splitting plus recession of the lateral rectus muscle (LR) for reducing globe retraction. MR recession, with or without adjustable sutures, may be simultaneously combined with partial thickness vertical rectus muscle transposition (VRT) or with superior rectus muscle transposition (SRT). We describe a novel combination of surgical procedures in the management of esotropic-DRS in two patients. In our first patient, following an initial MR recession combined with LR disinsertion and periosteal fixation (LRDAPF), a modified Nishida procedure was performed. In our second patient following a prior simultaneous MR recession and LR Y splitting with recession, we combined periosteal fixation of the LR with a modified Nishida procedure of the vertical rectus muscles.

Forty-five Years of Studying Intermittent Exotropia - What Have I Learned? The WSPOS Keynote Strabismus Lecture, October 3, 2020.

There are three keys to understanding how the new way of classifying and treating intermittent exotropia (IXT) differs from Burian's classic classification. First, the assumption that lateral rectus surgery selectively affects the distance deviation, recess/resect procedures affect the distance and near equally, and that medial rectus surgery selectively affects the near deviation, are false assumptions. Second, AC/A ratios in IXT can be calculated in all the usual manners, provided that any near measurement used in the calculation be made after prolonged monocular occlusion to eliminate the contaminating effect of the Scobee phenomenon. Third, the use of +3 diopter (D) lenses at near and prolonged monocular occlusion are not interchangeable and work on different mechanisms, the former on accommodative convergence and the latter on fusional convergence. All patients with IXT should have a measurement taken after prolonged monocular occlusion, as well as while fixating on a far distant outdoor target prior to surgery, which should target the largest angle measured.

The efficacy of strabismus surgery in adults: a review for primary care physicians.

Many adult patients with strabismus are under the misconception that nothing can be done to correct the problem or that treatment is associated with a high degree of risk. Moreover, many optometrists, comprehensive ophthalmologists and primary care physicians are similarly misinformed. In fact, most adult patients with strabismus can be successfully treated, with ∼80% of patients achieving satisfactory alignment with one surgical procedure. In addition, adult strabismus surgery carries a relatively low risk, with serious complications being anecdotal and rare. The majority of adults will experience some improvement in binocular function after strabismus surgery even if the strabismus has been longstanding. Most commonly this takes the form of an expansion of binocular visual fields; however, some patients may also regain stereopsis. Consequently, strabismus surgery in adults is not merely cosmetic in most cases. There are many psychological and interpersonal benefits to adult strabismus surgery. These benefits are highlighted by the finding that the majority of adults with strabismus would trade a portion of their life expectancy to be rid of their ocular misalignment. Although adult strabismus surgery has been shown to be highly cost-effective, many adults with strabismus can be successfully managed by non-surgical means. If an adult with strabismus is under the impression, or was told, they cannot be treated, or that treatment is risky, they should consider a referral to an ophthalmologist specifically specialising in strabismus.

Eccentric Gaze as a Possible Cause of "Zoom Fatigue".

BACKGROUND: The Covid-19 pandemic has led to a marked increase in the use of videoconferencing for social interaction. Many people report discomfort and disaffection with this modality, which has been labeled "Zoom Fatigue." Common videoconferencing hardware setups necessitate that if a user looks at the image of the person with whom they are in videoconference, they will not be looking directly at the camera and will appear to not be making direct eye contact. This study determined the minimum threshold of eccentric gaze in a videoconferencing setup above which subjects are perceived as not making direct eye contact by the majority of untrained observers. METHODS: Image captures were made of four subjects successively fixating at small increments eccentric to a video camera, both vertically and horizontally ranging from 0.9 degrees to 19 degrees of eccentricity. The images were embedded in separate Powerpoint files for each subject. Each file was assessed by seven graders who indicated whether or not they felt the subject was looking directly at them in each slide. RESULTS: The threshold for which 75% of the graders could detect that the subject was not looking at them ranged from only 2.7 degrees for horizontal eccentricity to 5.4 degrees for vertical eccentricity. CONCLUSION: The hardware setups commonly used for videoconferencing result in persistent eccentric gaze of the participating individuals if they look at the image of the other participants. In theory, this could be a contributing cause of Zoom Fatigue.

Definition of successful outcomes after surgery for each type of strabismus: a Delphi study.

BACKGROUND: The Delphi process has been widely used to delineate guidelines for the treatment of disorders for which there is little or no evidence in the published literature. The purpose of this study was to use the Delphi process to identify areas of consensus and disagreement on the definition of success after surgery for each type of strabismus. METHODS: Two rounds of electronic questionnaires were sent to 28 members of the Strabismus Success Definition Delphi Study Group. For the first round, responses to 70 questions were captured as agree (= 1) and disagree (= 2). For round 2, a total of 89 questions were captured on a Likert scale ranging from 1 (strongly disagree) to 7 (strongly agree). Consensus was determined a priori at 85%. RESULTS: In both the first and second rounds, inter-rater agreement of 85% consensus was reached for only 20% of questions. Intra-rater agreement per question was low, with κ values ranging from -0.11 to 0.62. Intra-rater agreement was also low among themes, ranging from poor to fair agreement: κ = 0.25 for motor, κ = 0.28 for sensory, and κ = 0.35 for follow-up. CONCLUSIONS: This study highlights consensus areas that could be considered by researchers in designing studies and identifies areas where lack of consensus indicates that further research is needed.

Observations about objective and subjective ocular torsion.

OBJECTIVE: To investigate the relationship between objective and subjective torsion in patients with cyclovertical strabismus and determine whether objective torsion differs according to which eye is fixing. DESIGN: A prospective evaluation of tests of objective and subjective torsion. PARTICIPANTS: Thirty-six patients with various types of cyclovertical strabismus. METHODS: Subjective torsion was assessed with the double Maddox rod, and objective torsion was graded in a masked manner from fundus photographs. MAIN OUTCOME MEASURES: Quantification of objective or subjective torsion. RESULTS: Objective torsion was the same regardless of which eye was used for fixation. However, after prolonged occlusion of the nonaffected eye, there was often an increase in objective torsion in the nonaffected eye. Subjective torsion typically was absent in patients with objective torsion if they did not have bifoveal fusion but was similar to objective torsion in patients with bifoveal fusional potential. CONCLUSIONS: Assessment of objective and subjective torsion are each important but play separate roles in the evaluation of cyclovertical strabismus. There is no immediate torsional motor shift when fixation switches from the nonaffected to the affected eye. However, prolonged fixation of the affected eye may possibly result in a motor torsional change in the nonaffected eye in some patients.

Conservative management of intermittent exotropia to defer or avoid surgery.

BACKGROUND: Surgery for intermittent exotropia performed at a very young age has poorer sensory outcomes than surgery performed later; moreover, postoperative recurrence is common, regardless of age. Alternate occlusion decreases the size of the exotropia and improves control. The purpose of this study was to report the long-term effects of part-time alternate occlusion and overminus spectacles combined with prism on delaying or avoiding surgery in intermittent exotropia. METHODS: The study included consecutive patients from 1979 to 2010 who had poorly controlled intermittent exotropia and were treated with alternate occlusion, followed in some cases by overminus spectacles with base-in prism. Outcome measures were initial improvement and subsequent time to surgery, if required. RESULTS: A total of 279 patients had initial control poor enough to otherwise be considered candidates for surgery. After occlusion therapy, 219 (78%) improved their angle and control, and 62 (22%) converted to an exophoria. After 1 year, 9 cases deteriorated, and surgery was recommended. In 207 (74%), conservative treatment delayed surgery for at least 1 year. At 20 years, 42 of 279 patients were still being followed. Of these, 22 of 219 (7%) were known to have not undergone surgery, and 127 (45%) had undergone surgery; 130 (47%) were lost to follow-up. CONCLUSIONS: Part-time alternate occlusion and overminus spectacles with prism can defer the need for surgery in a large percentage of patients with intermittent exotropia; for a small number it may be curative.

Use of the Delphi process for defining successful outcomes for strabismus surgery.

The purpose of this review was to identify areas of consensus and disagreement among experts for the definition of success following strabismus surgery using the Delphi process. Three rounds of electronic questionnaires were sent to a panel of 28 strabismus experts. Throughout the process, members of the panel were masked to one another's identities to minimize the possibility of influence among members. Prior to data collection, we defined consensus as an 85% agreement on the answer to each question. Questions for which there was no consensus were reworded, and the resultant new questions were used in each subsequent round of questioning. We arrived at consensus for 23 of the 36 questions (64%). Consensus was obtained for recommending unique criteria for the definition of success for certain specific strabismus conditions. In addition, it was considered important that stereopsis and the range of single binocular vision be included in the definition of success for certain types of strabismus.

The Functional Benefits of Strabismus Surgery.

When performed prior to visual maturity, strabismus surgery can result in the development or recovery of binocularity. When strabismus surgery is performed after visual maturity, the functional benefits of the surgery should be dichotomized according to whether the onset of the strabismus was before or after visual maturity. If the onset was after visual maturity, patients typically are diplopic. Specific success rates for eliminating diplopia vary according to the nature of the strabismus; however, overall the success rate is quite high. There is a common misperception that surgery in adults for strabismus that began prior to visual maturity is merely cosmetic. Numerous studies contradict this misconception. Even if the strabismus has been longstanding, most adults will experience some improvement in binocular function after strabismus surgery. In esotropic patients, this improvement typically takes the form of an expansion of binocular visual fields; however, some patients may also regain stereopsis. There are many psychosocial benefits to adult strabismus surgery. This is reflected in the finding that the majority of adults surveyed with strabismus would trade a portion of their life expectancy to be rid of their strabismus.

Re-Operation Strategies in Strabismus-Cooper's Dictum Amended.

PURPOSE: To outline a systematic approach to strabismus reoperations. Many strabismologists have a formulaic approach to strabismus reoperations, e.g., treat it as a fresh case, advance previously recessed muscles to the original insertion, etc. Patients and methods: This paper is a collection of pearls gained from the author's 40+ years in practice. RESULTS: Effective strategies for strabismus reoperations are not formulaic and should be tailored to the specific history and findings of the patient. The first, and most important decision, is whether to operate on previously operated muscles or fresh muscles. This should be influenced, in part, by whether one is treating an overcorrection or undercorrection. Limitations of rotations and incomitance patterns should be addressed. Many important decisions should be made intraoperatively based on where muscles are found, their integrity (slipped in the capsule, stretched scar, etc.), repeated intraoperative forced ductions, and spring back balance testing. CONCLUSION: A proper plan for a strabismus reoperation takes into account a number of preoperative factors, and the surgeon should be prepared to modify the plan based on intraoperative findings.

Long-Term Follow-Up of Cyclic Esotropia.

BACKGROUND AND PURPOSE: To describe the development and treatment of patients with cyclic esotropia. PATIENTS AND METHODS: The clinical course of seven patients with cyclic esotropia were retrospectively reviewed and described. All patients underwent bilateral medial rectus recession based on the deviation manifested on the day they were esotropic. Additionally, one patient had previously undergone surgery for intermittent exotropia. RESULTS: All patients developed excellent postoperative alignment. After strabismus surgery, normal eye alignment with some degree of binocularity was reached in five patients. Moreover, there was no recurrence of the cyclic deviation in any patient, and no patient experienced an overcorrection. CONCLUSIONS: Strabismus surgery aimed to correct the horizontal esotropic angle present on the day the esotropia is manifested provides a good outcome that is stable long-term, with minimal risk of overcorrection. Possible explanations for the origin of cyclic esotropia are discussed.

Retinothalamic White Matter Abnormalities in Amblyopia.

Purpose: Amblyopia is associated with a broad array of perceptual and neural abnormalities in the visual system, particularly in untreated or unsuccessfully treated populations. Traditionally, it has been believed that the neural abnormalities are confined to the visual cortex and subcortex (e.g., lateral geniculate nucleus). Here, we investigate the presence of neuroanatomical abnormalities earlier in the visual stream, in the optic nerves and tracts, of participants with two predominant forms of amblyopia. Methods: We used diffusion magnetic resonance imaging and probabilistic tractography to compare the microstructural properties of five white matter visual pathways between 15 participants with amblyopia (eight anisometropic, five strabismic, and two exhibiting both etiologies), and 13 age-matched controls. Results: Participants with amblyopia exhibited significantly smaller mean fractional anisotropy in the optic nerve and optic tract (0.26 and 0.31 vs. 0.31 and 0.36 in controls, respectively). We also found greater mean diffusivity in the optic radiation compared to controls (0.72 µm2/s vs. 0.68 µm2/s, respectively). Comparing etiologies, the abnormalities in the precortical pathways tended to be more severe in participants with anisometropic compared to strabismic amblyopia, and anisometropic participants' optic nerves, optic tracts, and optic radiations significantly differed from control participants' (all, P < 0.05). Conclusions: The results indicate that amblyopia may be associated with microstructural abnormalities in neural networks as early as the retina, and these abnormalities may differ between amblyopic etiologies.