Electronically monitored occlusion therapy in amblyopia with eccentric fixation

Purpose Amblyopia with eccentric fixation, especially when not diagnosed early, is a therapeutic challenge, as visual outcome is known to be poorer than in amblyopia with central fixation. Consequently, treatment after late diagnosis is often denied. Electronic monitoring of occlusion provides us the chance to gain first focussed insight into age-dependent dose response and treatment efficiency, as well as the shift of fixation in this rare group of paediatric patients. Methods In our prospective pilot study, we examined amblyopes with eccentric fixation during 12 months of occlusion treatment. We evaluated their visual acuity, recorded patching duration using a TheraMon®-microsensor, and determined their fixation with a direct ophthalmoscope. Dose-response relationship and treatment efficiency were calculated. Results The study included 12 participants with strabismic and combined amblyopia aged 2.9–12.4 years (mean 6.5). Median prescription of occlusion was 7.7 h/day (range 6.6–9.9) and median daily received occlusion was 5.2 h/day (range 0.7–9.7). At study end, median acuity gain was 0.6 log units (range 0–1.6) and residual interocular visual acuity difference (IOVAD) 0.3 log units (range 0–1.8). There was neither significant acuity gain nor reduction in IOVAD after the 6th month of treatment. Children younger than 4 years showed best response with lowest residual IOVAD at study end. Efficiency calculation showed an acuity gain of approximately one line from 100 h of patching in the first 2 months and half a line after 6 months. There was a significant decline of treatment efficiency with age (p = 0.01). Foveolar fixation was achieved after median 3 months (range 1–6). Three patients (> 6 years) did not gain central fixation. Conclusion Eccentric fixation is a challenge to therapy success. Based on electronic monitoring, our study quantified for the first time the reduction of treatment efficiency with increasing age in amblyopes with eccentric fixation. Despite some improvement in patients up to 8 years, older patients showed significantly lower treatment efficiency. In younger patients with good adherence, despite poor initial acuity, central fixation and low residual IOVAD could be attained after median 3 months. Hence, the necessity of early diagnosis and intensive occlusion should be emphasized.

Evaluation of strabismus in 0-18 years of age group in tertiary health care hospital: A prospective cross-sectional observational study

The main objective of the study was to study the pattern of strabismus, determine the type of refractive error and measure the angle of deviation, determine streoacuity by WFDT in 0-18 years of age group. This was a prospective cross-sectional observational study. Total 50 patients were taken. Patients of 0-18 years of age presenting with squint included in study. Patients were evaluated for VA, both distance and near vision without glasses as well as BCVA tested. Anterior segment evaluation using slit lamp, cycloplegic refraction using atropine (0-9 years) or cyclopentolate (10-18 years), fundus examination, PBCT, WFDT test done. In study, total 50 subjects of 0-18 years of age group was taken. In them boys were more than girls. 49(98%) had comitant strabismus and 1(2%) had incomitant strabismus. 32(64%) had esotropia and 18(36%) had exotropia. Among esotropia 11(34.37%) had accommodative esotropia, 13(40.62%) had partially accommodative, 7(21.87%) had non accommodative, 1(3.12%) had restrictive esotropia. Among exotropia 9(50%) had basic exotropia, 6(33.33%) had divergence excess and 3(16.66%) had convergence insufficiency. 14(28%) had amblyopia. 32(64%) had hypermetropia and 18(36%) had Myopia. 33(64%) had central fixation and 12(24%) had eccentric fixation. In binocularity, 6(12%) had ARC, 25(50%) had unilateral suppression, 10(20%) had alternate suppression.Comitant squint was more common than incomitant squint. Among comitant squint, esotropia was more common than exotropia.

Pupil size in the evaluation of static and dynamic stimuli in peripheral vision

It has been evidenced that in attention-window tasks, the participants fixate on the center of a screen while inspecting two stimuli that appear at the same time in parafoveal vision. Such tasks have successfully been used to estimate a person’s breadth of attention under various conditions. While behavioral investigations of visual attention have often made use of response accuracy, recent research has shown that the pupil size can also be used to track shifts of attention to the periphery. The main finding of previous studies is that the harder the evaluation of the stimuli becomes, e.g., because they appear farther away from the central fixation point, the stronger the pupils dilate. In this paper, we present experimental data suggesting that in an attention-window task, the pupil size can also be used to assess whether the participants attend to static, non-moving, or dynamic, moving stimuli. That is, regression models containing information on presentation mode (static vs. dynamic) and the visual angle between spatially separated stimuli better predict accuracy of perception and pupil dilation than model without these sources of information. This finding is useful for researchers who aim at understanding the human attentional system, including potential differences in its sensitivity to static and dynamic objects.

Ultra-wide field swept-source optical coherence tomography angiography in patients with diabetes without clinically detectable retinopathy

Background To investigate alterations in retinal microvasculature in eyes with preclinical diabetic retinopathy (DR) using ultra-wide field swept-source optical coherence tomography angiography (UWF SS OCTA). Methods Prospective cross-sectional study. Fifty-five eyes of 30 diabetic patients without clinical retinal signs were included. All subjects underwent OCTA examination with a 12 × 12 mm2 field of view of 5 visual fixations (1 central fixation and 4 peripheral fixations) to compose a UWF OCTA image. In the UWF images, the central area corresponded to the original central image obtained using central fixation, and the peripheral area was the remaining area. Lesions, including nonperfusion areas (NPAs), microvascular dilation and tortuosity, and neovascularization (NV), were recorded in different areas. Diabetes history was also recorded. Results Peripheral areas presented significantly more microvascular dilation and tortuosity than central areas (P = 0.024) and more NPAs than central areas, with borderline significance (P = 0.085). The number of lesion types was associated with HbA1c levels in the peripheral and overall areas (all P values < 0.001). Conclusions UWF SS OCTA is a promising imaging method for detecting vascular alterations in diabetic eyes without clinical signs to reveal retinal microvascular alterations. These alterations were correlated with systemic conditions.

A comparison of the apparent gloss of rendered objects presented in the lower and upper regions of the visual field

Gloss is an aspect of surface perception that is important for understanding the material properties of the environment. Because a surface can stimulate any region of the visual field during natural viewing, it is of interest to measure the potential influence of visual field asymmetries on perceived gloss—as such asymmetries could make the perception of gloss dependent on the visual field location. Here, our aim was to compare the apparent glossiness of renderings of nondescript objects when positioned in the lower and upper regions of the visual field. In Experiment 1, participants (n=20) evaluated the glossiness of objects presented simultaneously below and above central fixation. Estimates of the specular reflectance required for perceptual gloss equality indicated little effect of the visual field location. In Experiment 2, participants (n=19) compared the magnitude of gloss differences across two pairs of objects in either the lower or the upper visual field. Estimates of the exponent relating specular reflectance to a gloss difference scale and a noise parameter again indicated little effect of the visual field location. Overall, these estimates are consistent with the existence of a high degree of gloss constancy across presentations in the lower and upper visual fields.

Attention Biases Competition for Visual Representation via Dissociable Influences from Frontal and Parietal Cortex

What mechanisms underlie the prioritization of neural representations of visually perceived information to guide behavior? We assessed the dynamics whereby attention biases competition for representation of visual stimuli by enhancing representations of relevant information and suppressing the irrelevant. Multivariate pattern analysis (MVPA) classifiers were trained to discriminate patterns of fMRI activity associated with each of three stimuli, within several predefined ROIs. Participants performed a change-detection task wherein two of three presented items flashed at 1 Hz, one to each side of central fixation. Both flashing stimuli would unpredictably change state, but participants covertly counted the number of changes only for the cued item. In the ventral occipito-temporal ROI, MVPA evidence (a proxy for representational fidelity) was dynamically enhanced for attended stimuli and suppressed for unattended stimuli, consistent with a mechanism of biased competition between stimulus representations. Frontal and parietal ROIs displayed a qualitatively distinct, more “source-like” profile, wherein MVPA evidence for only the attended stimulus could be observed above baseline levels. To assess how attentional modulation of ventral occipito-temporal representations might relate to signals originating in the frontal and/or parietal ROIs, we analyzed informational connectivity (IC), which indexes time-varying covariation between regional levels of MVPA evidence. Parietal-posterior IC was elevated during the task, but did not differ for cued versus uncued items. Frontal-posterior IC, in contrast, was sensitive to an item's priority status. Thus, although regions of frontal and parietal cortex act as sources of top–down attentional control, their precise functions likely differ.

'Clap your hands' or 'take your hands'? One-year-olds distinguish between frequent and infrequent multiword phrases

Although words are often described as the basic building blocks of language, there is growing evidence that multiword sequences also play an integral role in language learning and processing. It is still not known, however, whether children become sensitive to multiword information at an age when they are still building knowledge of individual words. Using a central fixation paradigm, the present study examined whether infants between 11 and 12 months (N=36) distinguish between three-word sequences (trigrams) with similar substring frequencies but different multiword frequency in infant-directed speech (e.g., high frequency: ‘clap your hands’ vs. low frequency: ‘take your hands’). Infants looked significantly longer at frequent trigrams compared to infrequent ones. This provides the first evidence that infants at the cusp of one-word production are already sensitive to the frequency of multiword sequences, and suggests they represent linguistic units of varying sizes from early on, raising the need to evaluate knowledge of both words and larger sequences during development.l