The effect of font size on reading performance in strabismic amblyopia: an eye movement investigation.

PURPOSE: We investigated the effect of font size on reading speed and ocular motor performance in strabismic amblyopes during text reading under monocular and binocular viewing conditions. METHODS: Eye movements were recorded at 250 Hz using a head-mounted infrared video eye tracker in 15 strabismic amblyopes and 18 age-matched controls while silently reading paragraphs of text at font sizes equivalent to 1.0 to 0.2 logMAR acuity. Reading under monocular viewing with amblyopic eye/nondominant eye and nonamblyopic/dominant eye was compared to binocular viewing. Mean reading speed; number, amplitude, and direction of saccades; and fixation duration were calculated for each font size and viewing condition. RESULTS: Reading speed was significantly slower in amblyopes compared to controls for all font sizes during monocular reading with the amblyopic eye (P = 0.004), but only for smaller font sizes for reading with the nonamblyopic eye (P = 0.045) and binocularly (P = 0.038). The most significant ocular motor change was that strabismic amblyopes made more saccades per line than controls irrespective of font size and viewing conditions (P < 0.05 for all). There was no significant difference in saccadic amplitudes and fixation duration was only significantly longer in strabismic amblyopes when reading smaller fonts with the amblyopic eye viewing. CONCLUSIONS: Ocular motor deficits exist in strabismic amblyopes during reading even when reading speeds are normal and when visual acuity is not a limiting factor; that is, when reading larger font sizes with nonamblyopic eye viewing and binocular viewing. This suggests that these abnormalities are not related to crowding

Pediatric Optical Coherence Tomography in Clinical Practice-Recent Progress

PURPOSE: Optical coherence tomography (OCT) has revolutionized the diagnosis and management of adult retinal and optic nerve disease. Children were deprived of this technology until the recent development of handheld spectral-domain OCT (HH-SDOCT). In this article, we review the applications of OCT imaging in pediatric ophthalmology. METHODS: This study was a review of the literature. RESULTS: The acquisition and interpretation of pediatric tomograms differ significantly from those for adults, with adjustments needed to account for the shorter axial lengths, higher refractive errors, and ongoing retinal and optic nerve development in the pediatric eye. Handheld SDOCT is increasingly being used as an adjunctive diagnostic tool in retinopathy of prematurity (ROP) and nonaccidental injury (NAI) by providing additional morphologic information that is not normally clinically discernible. The role of HH-SDOCT in streamlining diagnosis in infantile nystagmus syndrome, retinal dystrophies, and degenerations has been established. Optical coherence tomography can also help differentiate between pediatric intraocular tumors, for example, hamartomas and retinoblastoma; monitor tumor progression; and monitor treatment response. In addition, HH-SDOCT is establishing its role as a noninvasive monitoring tool in children affected by optic nerve pathology such as glaucoma, optic nerve atrophy and hypoplasia, optic pathway glioma, and pseudotumor cerebri. CONCLUSIONS: Handheld SDOCT can provide novel insights into the natural history of retinal and optic nerve diseases in young children. For example, in achromatopsia and albinism, in vivo OCT studies have provided evidence of altered but ongoing retinal development in early childhood, which suggests that potentially targeting treatment at an earlier age may optimize visual function by normalizing retinal development

Altered whole-brain connectivity in albinism

Albinism is a group of congenital disorders of the melanin synthesis pathway. Multiple ocular, white matter and cortical abnormalities occur in albinism, including a greater decussation of nerve fibres at the optic chiasm, foveal hypoplasia and nystagmus. Despite this, visual perception is largely preserved. It was proposed that this may be attributable to reorganisation among cerebral networks, including an increased interhemispheric connectivity of the primary visual areas. A graph-theoretic model was applied to explore brain connectivity networks derived from resting-state functional and diffusion-tensor magnetic resonance imaging data in 23 people with albinism and 20 controls. They tested for group differences in connectivity between primary visual areas and in summary network organisation descriptors. Main findings were supplemented with analyses of control regions, brain volumes and white matter microstructure. Significant functional interhemispheric hyperconnectivity of the primary visual areas in the albinism group were found (P = 0.012). Tests of interhemispheric connectivity based on the diffusion-tensor data showed no significant group difference (P = 0.713). Second, it was found that a range of functional whole-brain network metrics were abnormal in people with albinism, including the clustering coefficient (P = 0.005), although this may have been driven partly by overall differences in connectivity, rather than reorganisation. Based on the results, it was suggested that changes occur in albinism at the whole-brain level, and not just within the visual processing pathways. It was proposed that their findings may reflect compensatory adaptations to increased chiasmic decussation, foveal hypoplasia and nystagmus. Hum Brain Mapp 38:740-752, 2017. © 2016 Wiley Periodicals, Inc

High-Resolution Imaging of the Optic Nerve and Retina in Optic Nerve Hypoplasia.

To investigate the optic nerve and macular morphology in patients with optic nerve hypoplasia (ONH) using spectral-domain optical coherence tomography (SD OCT)

Hand-held optical coherence tomography imaging in children with anterior segment dysgenesis

In this study, we investigated the potential of hand-held optical coherence tomography to improve diagnosis in anterior segments (AS) by visualizing the ante- rior and posterior eye structures with- out general anaesthetic (GA) or sedation

Hand-held optical coherence tomography imaging in children with anterior segment dysgenesis

In this study, we investigated the potential of hand-held optical coherence tomography to improve diagnosis in anterior segments (AS) by visualizing the ante- rior and posterior eye structures with- out general anaesthetic (GA) or sedation

Association Between Adherence to Glasses Wearing During Amblyopia Treatment and Improvement in Visual Acuity

Importance Occlusion dose monitors have helped establish that better adherence to occlusion is associated with improved visual outcomes in patients undergoing amblyopia treatment. However, the role of adherence to glasses wearing is unknown. Objectives To establish the feasibility and reliability of objectively monitoring adherence to glasses wearing using age-based norms, establish the association between adherence to glasses wearing and improvement in visual acuity (VA) after optical treatment and occlusion therapy, and analyze the effect of age, sex, refractive errors, type of amblyopia, and adherence to glasses wearing on improvement in VA. Design, Setting, and Participants A prospective, observational, nonmasked, cohort study was conducted between June 8, 2008, and June 30, 2013, among patients at a pediatric ophthalmology clinic of a tertiary care hospital who were newly diagnosed with anisometropic and/or strabismic amblyopia and had not undergone previous treatment. The study consisted of a glasses phase (18 weeks) and a patching phase (glasses and occlusion for 10 hours per day for 12 weeks). Reliability of the glasses monitors was assessed by comparing diary entries and monitor recordings in adults. Interventions Objective monitoring of glasses wearing and occlusion. Main Outcomes and Measures Adherence to glasses wearing (hours per day) and effect on VA. Results Among 20 children with anisometropia (mean [SD] age, 6.20 [2.16] years; 11 boys and 9 girls) and 20 with strabismic or mixed amblyopia (mean [SD] age, 4.90 [1.36] years; 10 boys and 10 girls), adherence to glasses wearing was successfully monitored in all but 1 patient. Agreement between diaries and monitored times wearing glasses in adults was high (intraclass correlation coefficient, 1.00; 95% CI, 0.999-1.00). Median (SD) adherence to glasses wearing was 70% (25.3%). A moderate correlation was observed between adherence to glasses wearing and percentage improvement in VA during the glasses phase (r = 0.462; P = .003). Multiple regression revealed that age (β = –0.535; P = .001), type of amblyopia (β = –0.347; P = .02), and adherence to glasses wearing (β = 0.287; P = .04) were independently associated with improvement in VA after the glasses phase and explained 42% of the variability (F3,35 = 8.457; P < .001). A strong correlation between glasses wearing and occlusion adherence was observed (r = 0.719; P < .001). Conclusions and Relevance The results suggest that adherence to glasses wearing is less than optimal and highly variable but is important in achieving good VA. This study emphasizes the importance of encouraging children to not only have good adherence to occlusion therapy but also to glasses wearing

Reading Individual Words in Sentences in Infantile Nystagmus

Purpose: Normal readers make immediate and precise adjustments in eye movements during sentence reading in response to individual word features, such as lexical difficulty (e.g. common or uncommon words) or word length. Our purpose was to assess the effect of infantile nystagmus (IN) on these adaptive mechanisms. Methods: Eye movements were recorded from 29 participants with IN (14 albinism, 12 idiopathic and 3 congenital stationary night blindness) and 15 controls when reading sentences containing either common / uncommon words or long / short target words. Parameters assessed included: duration of first foveation / fixation, number of first-pass and percentage second-pass foveations / fixations, percentage words skipped, gaze duration, acquisition time (gaze + non-gaze duration), landing site locations, clinical and experimental reading speeds. Results: Participants with IN could not modify first foveation durations in contrast to controls who made longer first fixations on uncommon words (P<0.001). Participants with IN made more first-pass foveations on uncommon and long words (P<0.001) to increase gaze durations. However, this also increased non-gaze durations (P<0.001) delaying acquisition times. Participants with IN re-read shorter words more often (P<0.005). Similar to controls, participants with IN landed more first foveations between the start and center of long words. Reading speeds during experiments were lower in IN participants compared to controls (P<0.01). Conclusions: People with IN make more first-pass foveations on uncommon and long words influencing reading speeds. This demonstrates that the ‘slow to see’ phenomenon occurs during word reading in IN. These deficits were not captured by clinical reading charts

In vivo morphology of the optic nerve and retina in patients with Parkinson’s disease

PURPOSE: To investigate optic nerve (ON) and macular morphology in patients with Parkinson’s disease (PD) using spectral-domain optical coherence tomography (SD-OCT). SUBJECTS. Twenty-five participants with PD (19 males and 6 females; mean age 60.79; SD 6 9.24) and 25 sex-, age-, ethnicity-, and refraction-matched healthy controls. METHODS: A high-resolution SD-OCT device was used to acquire scans in 25 participants with PD (mean age 60.79; 6 SD 9.24) and 25 sex-, age-, ethnicity-, and refraction-matched healthy controls. Main outcome measures included optic nerve head parameters (disc/cup diameters/ areas, cup/rim volumes, cup depth, cup/disc ratio; peripapillary retinal nerve fiber layer [ppRNFL] thickness), retinal thickness (in inner and outer annuli around the foveal center) and thickness of individual retinal layers. RESULTS: Our study showed significant ppRNFL thinning in PD patients in all quadrants (P < 0.05) associated with a shallower optic cup (P = 0.03) as compared with controls. Foveal remodelling with retinal thinning (nasal and temporal segments in both annuli; and superior segment in outer annulus; P < 0.05), foveal pit widening (P = 0.05), central outer plexiform layer (OPL) thickening (P < 0.001), and nasal RPE thinning (P < 0.001) was also found in PD. The differences were more obvious in hemiretinae related to the predominantly affected cerebral hemisphere. Changes were more pronounced in advanced stages and longer PD duration. CONCLUSIONS: Optic nerve changes in PD are likely to be caused by primary neurodegeneration. Central retinal thinning, pit widening, central OPL thickening, and RPE thinning indicate foveal remodelling. Specific changes of the fovea and thinning of individual retinal layers, correlating with disease severity and duration, indicate that ON and retinal changes have potential to be used as biomarkers for PD

Retinal layer abnormalities as biomarkers of schizophrenia

Objective Schizophrenia is associated with several brain deficits, as well as visual processing deficits, but clinically-useful biomarkers are elusive. We hypothesised that retinal layer changes, non-invasively visualized using spectral-domain optical coherence tomography (SD-OCT), may represent a possible “window” to these abnormalities. Methods A Leica EnvisuTM SD-OCT device was used to obtain high-resolution central foveal B-scans in both eyes of 35 patients with schizophrenia and 50 demographically-matched controls. Manual retinal layer segmentation was performed to acquire individual and combined layer thickness measurements in three macular regions. Contrast sensitivity was measured at three spatial frequencies in a sub-group of each cohort. Differences were compared using adjusted linear models and significantly different layer measures in patients underwent Spearman Rank correlations with contrast sensitivity, quantified symptoms severity, disease duration and antipsychotic medication dose. Results Total retinal and photoreceptor complex thickness was reduced in all regions in patients (P<0.0001). Segmentation revealed consistent thinning of the outer nuclear layer (P<0.001) and inner segment layer (P<0.05), as well as a pattern of parafoveal ganglion cell changes. Low spatial frequency contrast sensitivity was reduced in patients (P=0.002) and correlated with temporal parafoveal ganglion cell complex thinning (R=0.48, P=0.01). Negative symptom severity was inversely correlated with foveal photoreceptor complex thickness (R=-0.54, P=0.001) and outer nuclear layer thickness (R=-0.47, P=0.005). Samani et al. 4 Conclusions Our novel findings demonstrate considerable retinal layer abnormalities in schizophrenia that are related to clinical features and visual function. With time, SD-OCT could provide easily-measurable biomarkers to facilitate clinical assessment and further our understanding of the disease