Platelet and Erythrocyte Extravasation across Inflamed Corneal Venules Depend on CD18, Neutrophils, and Mast Cell Degranulation.

Platelet extravasation during inflammation is under-appreciated. In wild-type (WT) mice, a central corneal epithelial abrasion initiates neutrophil (PMN) and platelet extravasation from peripheral limbal venules. The same injury in mice expressing low levels of the ß2-integrin, CD18 (CD18hypo mice) shows reduced platelet extravasation with PMN extravasation apparently unaffected. To better define the role of CD18 on platelet extravasation, we focused on two relevant cell types expressing CD18: PMNs and mast cells. Following corneal abrasion in WT mice, we observed not only extravasated PMNs and platelets but also extravasated erythrocytes (RBCs). Ultrastructural observations of engorged limbal venules showed platelets and RBCs passing through endothelial pores. In contrast, injured CD18hypo mice showed significantly less venule engorgement and markedly reduced platelet and RBC extravasation; mast cell degranulation was also reduced compared to WT mice. Corneal abrasion in mast cell-deficient (KitW-sh/W-sh) mice showed less venule engorgement, delayed PMN extravasation, reduced platelet and RBC extravasation and delayed wound healing compared to WT mice. Finally, antibody-induced depletion of circulating PMNs prior to corneal abrasion reduced mast cell degranulation, venule engorgement, and extravasation of PMNs, platelets, and RBCs. In summary, in the injured cornea, platelet and RBC extravasation depends on CD18, PMNs, and mast cell degranulation.

Longitudinal Development of Refractive Error in Children Treated With Intravitreal Bevacizumab or Laser for Retinopathy of Prematurity.

Purpose: To compare the patterns of longitudinal refractive error development during the first 3.5 years in children with severe retinopathy of prematurity (ROP) treated with intravitreal bevacizumab (IVB) or laser photocoagulation. Methods: This prospective cohort study enrolled extremely preterm infants (birth weight < 1000 g, gestational age 23-27 weeks) with type 1 ROP from multiple hospitals in Dallas between 1999 and 2017; IVB group (N = 22); laser group (N = 26). Cycloplegic retinoscopy was conducted from 0.04 years corrected age and every 0.5 to 1.0 years thereafter until 3.5 years old. Right eye spherical equivalent (SEQ) and astigmatism, anisometropia, and better-eye visual acuity were analyzed over time. Results: In all children, both eyes were treated with the same modality. At the final visit, the prevalence of myopia (SEQ ≤ -1D) was 82.7% in the laser group and 47.7% in the IVB group (P < 0.05) with a mean SEQ of -8.0D ± 5.8D in the laser group versus -2.3D ± 4.2D in the IVB group (P < 0.001). Longitudinal SEQ were best fit with a bilinear model. Before one year, the rate of SEQ change was -5.0D/year in the laser group, but only -3.5D/year in the IVB group (T = -5.14, P < 0.001); after one year, there was a significant flattening of these slopes (T = 6.23, P < 0.001). Anisometropia in the IVB group was significantly less than in the laser group (P < 0.05). Final visual acuity in both groups was similar at 0.47 logMAR (∼ 20/60). Conclusions: Children with severe ROP treated with IVB developed less myopic refractive error than those treated with laser largely because of a slower rate of refractive change during the first year of life. Translational Relevance: These findings may inform decisions regarding ROP treatment timing and modality.

An Epithelial Abrasion Model for Studying Corneal Wound Healing.

The cornea is critical for vision, accounting for about two-thirds of the refractive power of the eye. Crucial to the role of the cornea in vision is its transparency. However, due to its external position, the cornea is highly susceptible to a wide variety of injuries that can lead to the loss of corneal transparency and eventual blindness. Efficient corneal wound healing in response to these injuries is pivotal for maintaining corneal homeostasis and preservation of corneal transparency and refractive capabilities. In events of compromised corneal wound healing, the cornea becomes vulnerable to infections, ulcerations, and scarring. Given the fundamental importance of corneal wound healing to the preservation of corneal transparency and vision, a better understanding of the normal corneal wound healing process is a prerequisite to understanding impaired corneal wound healing associated with infection and disease. Toward this goal, murine models of corneal wounding have proven useful in furthering our understanding of the corneal wound healing mechanisms operating under normal physiological conditions. Here, a protocol for creating a central corneal epithelial abrasion in mouse using a trephine and a blunt golf club spud is described. In this model, a 2 mm diameter circular trephine, centered over the cornea, is used to demarcate the wound area. The golf club spud is used with care to debride the epithelium and create a circular wound without damaging the corneal epithelial basement membrane. The resulting inflammatory response proceeds as a well-characterized cascade of cellular and molecular events that are critical for efficient wound healing. This simple corneal wound healing model is highly reproducible and well-published and is now being used to evaluate compromised corneal wound healing in the context of disease.

Binocular amblyopia treatment with contrast-rebalanced movies.

BACKGROUND: Binocular amblyopia treatments promote visual acuity recovery and binocularity by rebalancing the signal strength of dichoptic images. Most require active participation by the amblyopic child to play a game or perform a repetitive visual task. The purpose of this study was to investigate a passive form of binocular treatment with contrast-rebalanced dichoptic movies. METHODS: A total of 27 amblyopic children, 4-10 years of age, wore polarized glasses to watch 6 contrast-rebalanced dichoptic movies on a passive 3D display during a 2-week period. Amblyopic eye contrast was 100%; fellow eye contrast was initially set to a lower level (20%-60%), which allowed the child to overcome suppression and use binocular vision. Fellow eye contrast was incremented by 10% for each subsequent movie. Best-corrected visual acuity, random dot stereoacuity, and interocular suppression were measured at baseline and at 2 weeks. RESULTS: Amblyopic eye best-corrected visual acuity improved from 0.57 ± 0.22 at baseline to 0.42 ± 0.23 logMAR (t26 = 8.09; P < 0.0001; 95% CI for improvement, 0.11-0.19 logMAR). Children aged 3-6 years had more improvement (0.21 ± 0.11 logMAR) than children aged 7-10 years (0.11 ± 0.06 logMAR; t25 = 3.05; P = 0.005). Children with severe amblyopia (≥0.7 logMAR) at baseline experienced greater improvement (0.24 ± 0.12 logMAR) than children with moderate amblyopia at baseline (0.12 ± 0.06 logMAR; t25 = 3.49; P = 0.002). CONCLUSIONS: In this cohort, passive viewing of contrast-rebalanced dichoptic movies effectively improved visual acuity in amblyopic subjects. The degree of improvement observed was similar to that previously reported for 2 weeks of binocular games treatment and with 3-4 months of occlusion therapy.

Multiple-Choice Answer Form Completion Time in Children With Amblyopia and Strabismus.

Importance: Abnormal binocular experience during infancy or childhood from strabismus and/or anisometropia results in visual acuity deficits (eg, amblyopia) and impaired stereoacuity. These pediatric eye conditions have also been linked to slow reading and fine motor impairment. Objective: To assess an academic-related fine motor outcome-multiple-choice answer form completion time-in children with amblyopia and strabismus. Design, Setting, and Participants: In this cross-sectional study completed between May 2014 and November 2017 at a nonprofit eye research institute, 47 children with amblyopia treated for strabismus, anisometropia, or both, 18 children with nonamblyopic strabismus, and 20 normal controls were enrolled. Exposures: Children were asked to transfer the correct answers from a standardized reading achievement test booklet to a multiple-choice answer form as quickly as possible without making mistakes or reading the text. Main Outcomes and Measures: The time to complete the task was recorded and analyzed between groups. Results: Of the 85 included children, 40 (47%) were female, the mean (SD) age was 10.09 (0.91) years, and the last mean (SD) grade completed was 3.42 (0.92). Compared with children in the control group (mean [SD] time to completion, 230 [63] seconds), children with amblyopia (mean [SD] time to completion, 297 [97] seconds; difference, 63 seconds; 95% CI, 24-102; P = .001) and children with nonamblyopic strabismus (mean [SD] time to completion, 293 [53] seconds; difference, 68 seconds; 95% CI, 21-115; P = .002) required approximately 28% (95% CI, 20-37) more time to fill out a multiple-choice answer form. Completion time was not associated with etiology, visual acuity, or stereoacuity. Conclusions and Relevance: Multiple-choice answer forms typically accompany standardized testing in schools in the United States. Longer completion time in children with amblyopia or strabismus may affect a child's performance on tests using multiple-choice answer forms and may hinder academic success.

Slow reading in children with anisometropic amblyopia is associated with fixation instability and increased saccades.

BACKGROUND: Previous studies show slow reading in strabismic amblyopia. We recently identified amblyopia, not strabismus, as the key factor in slow reading in children. No studies have focused on reading in amblyopic children without strabismus. We examined reading in anisometropic children and evaluated whether slow reading was associated with ocular motor dysfunction in children with amblyopia. METHODS: Anisometropic children (7-12 years) with or without amblyopia were compared to age-similar normal controls. Children silently read a grade-appropriate paragraph during binocular viewing. Reading rate (words/min), number of forward and regressive saccades (per 100 words) and fixation duration were recorded with the ReadAlyzer. Binocular fixation instability was also evaluated (EyeLink 1000). RESULTS: Amblyopic anisometropic children read more slowly (n = 25; mean with standard deviation, 149 ± 42 words/min) than nonamblyopic anisometropic children (n = 15; 196 ± 80 words/min; P = 0.024) and controls (n = 25; 191 ± 65 words/min; P = 0.020). Nonamblyopic anisometropic children read at a comparable rate to controls (P = 0.81). Slow reading in amblyopic anisometropic children was correlated with increased forward saccades (r = -0.84, P < 0.001), increased regressive saccades (r = -0.85, P < 0.001), and fellow eye instability during binocular viewing (r = -0.52, P = 0.019). CONCLUSIONS: Slow reading in school-age children with anisometropic amblyopia is related to increased frequency of saccades and fixation instability of the fellow eye. Further research should consider the effects of slower reading on academic performance.

Modified Test Protocol Improves Sensitivity of the Stereo Fly Test.

BACKGROUND AND PURPOSE: Stereoacuity measurement is a common element of pediatric ophthalmic examinations. Although the Stereo Fly Test is routinely used to establish the presence of coarse stereopsis (3000 arcsecs), it often yields a false negative "pass" due to learned responses and non-stereoscopic cues. We developed and evaluated a modified Stereo Fly Test protocol aimed at increasing sensitivity, thus reducing false negatives. PATIENTS AND METHODS: The Stereo Fly Test was administered according to manufacturer instructions to 321 children aged 3-12 years. Children with a "pass" outcome (n = 147) were re-tested wearing glasses fitted with polarizers of matching orientation for both eyes to verify that they were responding to stereoscopic cues (modified protocol). The response to the standard Stereo Fly Test was considered a false negative (pass) if the child still pinched above the plate after disparity cues were eliminated. Randot® Preschool Stereoacuity and Butterfly Tests were used as gold standards. RESULTS AND CONCLUSIONS: Sensitivity was 81% (95% CI: 0.75 - 0.86) for standard administration of the Stereo Fly Test (19% false negative "pass"). The modified protocol increased sensitivity to 90% (95% CI: 0.85 - 0.94). The modified two-step protocol is a simple and convenient way to administer the Stereo Fly Test with increased sensitivity in a clinical setting.

Assessing Suppression in Amblyopic Children With a Dichoptic Eye Chart.

PURPOSE: Suppression has a key role in the etiology of amblyopia, and contrast-balanced binocular treatment can overcome suppression and improve visual acuity. Quantitative assessment of suppression could have a role in managing amblyopia. We describe a novel eye chart to assess suppression in children. METHODS: We enrolled 100 children (7-12 years; 63 amblyopic, 25 nonamblyopic with strabismus or anisometropia, 12 controls) in the primary cohort and 22 children (3-6 years; 13 amblyopic, 9 nonamblyopic) in a secondary cohort. Letters were presented on a dichoptic display (5 letters per line). Children wore polarized glasses so that each eye saw a different letter chart. At each position, the identity of the letter and its contrast on each eye's chart differed. Children read 8 lines of letters for each of 3 letter sizes. The contrast balance ratio was the ratio at which 50% of letters seen by the amblyopic eye were reported. RESULTS: Amblyopic children had significantly higher contrast balance ratios for all letter sizes compared to nonamblyopic children and controls, requiring 4.6 to 5.6 times more contrast in the amblyopic eye compared to the fellow eye (P < 0.0001). Amblyopic eye visual acuity was correlated with contrast balance ratio (r ranged from 0.49-0.57 for the 3 letter sizes). Change in visual acuity with amblyopia treatment was correlated with change in contrast balance ratio (r ranged from 0.43-0.62 for the 3 letter sizes). CONCLUSIONS: Severity of suppression can be monitored as part of a routine clinical exam in the management of amblyopia in children.

Amblyopic children read more slowly than controls under natural, binocular reading conditions.

BACKGROUND: Recent evidence suggests that amblyopia results in fixation instability and atypical saccades. Reading is a vision-reliant ability that requires sequential eye movements, including forward and regressive saccades. This study investigated reading and associated eye movements in school-age amblyopic children. METHODS: Amblyopic children with strabismus and/or anisometropia (n = 29) were compared to nonamblyopic children treated for strabismus (n = 23) and normal control children (n = 21). While fitted with the ReadAlyzer, an eye movement recording system, children silently read a grade-level paragraph of text during binocular viewing. Reading rate, number of forward and regressive saccades per 100 words, and fixation duration were determined. Comprehension was evaluated with a 10-item quiz; only data from children with at least 80% correct responses were included. RESULTS: Amblyopic children read more slowly and had more saccades compared with nonamblyopic children with treated strabismus and normal controls. Fixation duration did not differ significantly for amblyopic children versus normal controls. Treated strabismic children without amblyopia did not differ significantly from normal controls on any reading measure. Amblyopic eye visual acuity was not correlated with any reading measure. CONCLUSIONS: Amblyopia was associated with slower reading speed in school-age children. Treatment for monocular amblyopia visual acuity impairment could improve reading speed and efficiency.

Dichoptic movie viewing treats childhood amblyopia.

BACKGROUND: Contrast-balanced dichoptic experience with perceptual-learning tasks or simple games has been shown to improve visual acuity significantly in amblyopia. However, these tasks are intensive and repetitive, and up to 40% of unsupervised patients are noncompliant. We investigated the efficacy of a potentially more engaging movie method to provide contrast-balanced binocular experience via complementary dichoptic stimulation. METHODS: Eight amblyopic children 4-10 years of age were enrolled in a prospective cohort study to watch 3 dichoptic movies per week for 2 weeks on a passive 3D display. Dichoptic versions of 18 popular animated feature films were created. A patterned image mask of irregularly shaped blobs was multiplied with the movie images seen by the amblyopic eye and an inverse mask was multiplied with the images seen by the fellow eye. Fellow-eye contrast was initially set at a reduced level that allowed binocular vision and was then incremented by 10% at each visit. Best-corrected visual acuity, random dot stereoacuity, and interocular suppression were measured at baseline and 2 weeks. RESULTS: Mean amblyopic eye visual acuity (with standard error of the mean) improved from a logarithm of minimum angle of resolution of 0.72 ± 0.08 at baseline to 0.52 ± 0.09 (P = 0.003); that is, 2.0 lines of improvement at the 2-week outcome visit. No significant change in interocular suppression or stereoacuity was found. CONCLUSIONS: Passive viewing of dichoptic feature films is feasible and could be a promising new treatment for childhood amblyopia. The maximum improvement that may be achieved by watching dichoptic movies remains to be determined. No known side effects are associated with this new treatment.

Binocular iPad treatment for amblyopia in preschool children.

BACKGROUND: Recent experimental evidence supports a role for binocular visual experience in the treatment of amblyopia. The purpose of this study was to determine whether repeated binocular visual experience with dichoptic iPad games could effectively treat amblyopia in preschool children. METHODS: A total of 50 consecutive amblyopic preschool children 3-6.9 years of age were assigned to play sham iPad games (first 5 children) or binocular iPad games (n = 45) for at least 4 hours per week for 4 weeks. Thirty (67%) children in the binocular iPad group and 4 (80%) in the sham iPad group were also treated with patching at a different time of day. Visual acuity and stereoacuity were assessed at baseline, at 4 weeks, and at 3 months after the cessation of game play. RESULTS: The sham iPad group had no significant improvement in visual acuity (t4 = 0.34, P = 0.75). In the binocular iPad group, mean visual acuity (plus or minus standard error) improved from 0.43 ± 0.03 at baseline to 0.34 ± 0.03 logMAR at 4 weeks (n = 45; paired t44 = 4.93; P < 0.0001). Stereoacuity did not significantly improve (t44 = 1.35, P = 0.18). Children who played the binocular iPad games for ≥8 hours (≥50% compliance) had significantly more visual acuity improvement than children who played 0-4 hours (t43 = 4.21, P = 0.0001). CONCLUSIONS: Repeated binocular experience, provided by dichoptic iPad game play, was more effective than sham iPad game play as a treatment for amblyopia in preschool children.