Craniosynostosis (CS) can be associated with afferent visual pathway damage from the retina to the visual cortex. We therefore have incorporated VEP testing as part of our routine evaluation of CS patients since 2013.

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.

The pointing direction of cone photoreceptors can be inferred from the Stiles-Crawford Effect of the First Kind (SCE-I) measurement. Healthy retinas have tightly packed cones with a SCE-I function peak either centered in the pupil or with a slight nasal bias. Various retinal pathologies can change the profile of the SCE-I function implying that the arrangement or the light capturing properties of the cone photoreceptors are affected. Measuring the SCE-I may reveal early signs of photoreceptor change before actual cell apoptosis occurs. In vivo retinal imaging with adaptive optics (AO) was used to measure the pointing direction of individual cones at eight retinal locations in four control human subjects. Retinal images were acquired by translating an aperture in the light delivery arm through 19 different locations across a subject's entrance pupil. Angular tuning properties of individual cones were calculated by fitting a Gaussian to the reflected intensity profile of each cone projected onto the pupil. Results were compared to those from an accepted psychophysical SCE-I measurement technique. The maximal difference in cone directionality of an ensemble of cones, (rho) over bar, between the major and minor axes of the Gaussian fit was 0.05 versus 0.29 mm(-2) in one subject. All four subjects were found to have a mean nasal bias of 0.81 mm with a standard deviation of +/- 0.30 mm in the peak position at all retinal locations with mean (rho) over bar value decreasing by 23% with increasing retinal eccentricity. Results show that cones in the parafoveal region converge towards the center of the pupillary aperture, confirming the anterior pointing alignment hypothesis. (C) 2015 Elsevier Ltd. All rights reserved.

Repeated experience with dichoptic perceptual learning tasks and dichoptic game play have been shown to be effective in improving the visual acuity of amblyopic children and adults.1–4 However, whether the visual acuity gains achieved with binocular treatment are long lasting has not yet been addressed. We examined the durability of visual acuity improvements obtained as a result of binocular iPad game play in childhood amblyopia.

Many amblyopic patients have a structurally intact binocular visual system that can be revealed by decreasing the fellow-eye contrast to reduce the interocular suppression. We previously demonstrated that repeated binocular experience via at-home binocular iPad game play with reduced fellow-eye contrast was effective in treating childhood amblyopia and that visual acuity was maintained ≥12 months (ref 3). However, compliance was low in 32%-38% of children, primarily due to lack of interest in the games. Here we investigate the effectiveness of a potentially more engaging movie method to provide regular binocular experience via complementary dichoptic stimulation as a treatment for amblyopia.

Monocular amblyopia treatment (patching or penalization) does not always result in 6/6 vision and amblyopia often recurs. As amblyopia arises from abnormal binocular visual experience, we evaluated the effectiveness of a novel home-based binocular amblyopia treatment. Children (4–12 y) wore anaglyphic glasses to play binocular games on an iPad platform for 4 h/w for 4 weeks. The first 25 children were assigned to sham games and then 50 children to binocular games. Children in the binocular group had the option of participating for an additional 4 weeks. Compliance was monitored with calendars and tracking fellow eye contrast settings. About half of the children in each group were also treated with patching at a different time of day. Best-corrected visual acuity, suppression, and stereoacuity were measured at baseline, at the 4- and 8-week outcome visits, and 3 months after cessation of treatment. Mean (±SE) visual acuity improved in the binocular group from 0.47±0.03 logMAR at baseline to 0.39±0.03 logMAR at 4 weeks (P<0.001); there was no significant change for the sham group. The effect of binocular games on visual acuity did not differ for children who were patched vs those who were not. The median stereoacuity remained unchanged in both groups. An additional 4 weeks of treatment did not yield additional visual acuity improvement. Visual acuity improvements were maintained for 3 months after the cessation of treatment. Binocular iPad treatment rapidly improved visual acuity, and visual acuity was stable for at least 3 months following the cessation of treatment.

While suppression plays a key role in strabismic and anisometropic amblyopia, the exact relationship between suppression and visual acuity (VA) deficit remains unclear. In this study, we examined extent and severity of suppression in children participating in a study of binocular amblyopia treatment.

Most infants born hyperopic undergo emmetropization. However, about 15% retain hyperopia throughout the preschool years. We evaluated whether persistent hyperopia reflects reduced/absent axial growth (1) or whether developmental changes in other ocular components negate axial elongation (2) in a cohort of esotropic children with persistent hyperopia.

Purpose: We investigated the general mechanisms of disparity averaging. Methods: We employed a method of constant stimuli to measure the perceived depths for compound sine-wave gratings with two components placed at different depths. Observers compared perceived depths between two compound gratings: test and reference gratings. In each condition, both compound gratings contained the same spatial frequencies (SFs) and contrasts. Both components in the test grating were fixed at different disparities while the components for the reference grating had the same disparity. The reference disparity varied from trial to trial. The task was to indicate which grating was farther. Across conditions, component SFs and contrasts were varied independently and systematically. Results: At equal component contrast, the perceived depth is biased towards the disparity of the higher-frequency component. When the contrast of one of the components is reduced, the overall perceived depth moves towards the disparity of the other component. The rate of this change in perceived depth with respect to contrast differs for different SFs. The perceived depth as a function of contrast is systematically ordered with respect to ratios between the component SFs, independent of their absolute values. Conclusion: Both SF and contrast are significant factors in disparity averaging and they interact with each other. The general observation is that the greater the SF ratio, the greater the bias in perceived depth towards the higher SF.

Gratings with different disparities are sometimes seen as transparent surfaces, each with a distinct depth, when they are superimposed, and sometimes they are seen as a coherent plaid confined to a single depth plane--stereo analogs of transparent and coherent motion. Briefly presented sinusoidal gratings of similar spatial frequencies are seen to cohere in depth. The resulting plaid generally appears in a depth plane different from that of either component grating viewed separately; the plaid may even appear on the oppose side of fixation from the component gratings. Under similar viewing conditions, squarewave gratings are typically seen as transparent. Objective measures, gathered here using depth-order discriminations, show that the perception of transparency between squarewave gratings requires a minimum disparity difference that varies with the gratings' orientations. Gratings that are near orthogonal in orientation, or that give the plaid a near-horizontal disparity, favor the perception of coherence. Gratings that form a plaid having a large ratio of vertical to horizontal disparities favor the perception of transparency. The data are consistent with a Bayesian prior favoring single surfaces when disparities are small and near-horizontal. Disparities that are large or non-horizontal are more likely to be aperture disparities that result from viewing separate but overlapping surfaces. The sinewave-squarewave difference leads to the conclusion that coherence between components is required both for seeing a broadband pattern in a single depth plane and for seeing it in a different depth plane from other superimposed patterns.

The classic increment disparity threshold function rises steeply, usually exponentially, with disparity pedestal. Thus a smaller difference in stereoscopic depth can be resolved the nearer it is to the fixation plane. This result has been obtained with relatively broad-bandwidth stimuli. We show here that the increment threshold function for narrow-bandwidth stimuli differs subtly from the classic function: Thresholds vary only modestly over a +/- quarter-cycle pedestal range, by a factor of about 2, and frequently show a dip, yielding best stereo acuity not at the fixation plane but at moderate disparities (20 degrees-30 degrees in phase) on either side of it. Though the dip has not been noted previously, it is consistent with models of disparity processing in which filter sensitivity or selectivity is greatest at a disparity of zero. Moreover, the relatively flat increment threshold function observed at any one scale is compatible with a steeply rising function for broad-bandwidth stimuli.

Human stereo vision can resolve remarkably small depth differences between two stimuli, but the smallest resolvable difference is usually that between stimuli located near the plane of fixation. As distance from this plane increases, so does the smallest detectable increment in disparity. We examined this loss of resolution by comparing disparity discrimination thresholds for single-scale and multi-scale stimuli as a function of the pedestal disparity. For single-scale gratings, disparity thresholds display phase constancy; thus, their spatial thresholds vary reciprocally with grating spatial frequency. For multi-scale gratings, with components separated in frequency by two or three octaves, disparity thresholds display two types of interaction between coarse-scale and fine-scale components: facilitation when pedestal disparities are moderate and interference when they are large. The facilitation extends the disparity range that yields the low thresholds associated with fine-scale components, limiting the loss of disparity resolution for multi-scale stimuli.