A Rare Case of Juvenile X-Linked Retinoschisis

Aim: To present a rare clinical case of X-linked retinoschisis, confirmed clinically, electrophysiologically and genetically. Material and methods: A 12-year-old boy underwent detailed ophthalmic examination including fundus photography, full-field, multifocal and pattern electroretinography, visual field testing, optical coherence tomography, which established the clinical diagnosis, confirmed also genetically. Results: The clinical findings included a slight loss of vision, central and paracentral scotomas, a characteristic spoke-wheel pattern appearance of the macula in fundoscopy and the pathognomic appearance of splitting of the retinal layers in the macula with foveal schisis with cystic spaces on OCT. Reduced cone and rod ERG responds were detected with the characteristic decreasing of b-ware near the isoelectric line. The genetic analysis found that the patient was hemizygous for the missense mutation c.598G>A (p.Arg200Cys) of RS1 gene, coming from his asymptomatic mother. Conclusion: The comprehensive clinical, electrophysiological and genetic testing of patients with rare hereditary retinal dystrophies is essential for the correct diagnosis and the choice of therapeutic approach.

Optical Coherence Tomography and Pattern Electroretinography Changes in Egyptian Patients with Major Depressive Disorder

Background Major depressive disorder (MDD) is a common psychiatric disorder that affects nearly 11.1-14.6 % of the population in their lifetime. Pathophysiology and brain imaging findings show that degenerative and inflammatory processes may play a role. Meta-analysis of voxel-based morphometry studies in MDD demonstrated significant gray matter loss. From anatomical and embryological perspectives, the retina can be considered a unique extension of the brain and is able to reflect axonal histopathology. Being unmyelinated, it can provide insight into the pathophysiological processes of diseases with a neurodegenerative element. Aim to compare retinal optical coherence tomography (OCT) parameters in a group of MDD patients with a healthy control group and to correlate OCT parameters with pattern electroretinography (PERG) parameters. Method a controlled cross sectional study was conducted on 30 MDD patients and 28 age and sex matched controls. Both groups had a full ophthalmological examination, OCT imaging and 7 patients and 11 controls have PERG recorded. Results Thinning of the superior retinal nerve fiber layer, thinning of most of the ganglion cell inner plexiform (GCIP) layer, thinning of most of the macular thickness and thinning of macular volume in both eyes were detected. There was a statistically significant positive correlation between the left GCIP layer and the amplitude of the N95 wave. Also a statistically significant negative correlation existed between MDD duration in years with the left eye's average volume of the outer ring of the macula. Conclusion Significant retinal changes were detected by OCT in MDD patients supporting the theory of neurodegeneration as a pathophysiology of MDD.

Ocellar spatial vision in Myrmecia ants

In addition to the compound eyes, insects possess simple eyes known as ocelli. Input from the ocelli modulates optomotor responses, flight-time initiation, and phototactic responses—behaviours that are mediated predominantly by the compound eyes. In this study, using pattern electroretinography (pERG), we investigated the contribution of the compound eyes to ocellar spatial vision in the diurnal Australian bull ant Myrmecia tarsata by measuring the contrast sensitivity and spatial resolving power of the ocellar second-order neurons under various occlusion conditions. Furthermore, in four species of Myrmecia ants active at different times of the day, and in European honeybee Apis mellifera, we characterized the ocellar visual properties when both visual systems were available. Among the ants, we found that the time of activity had no significant effect on ocellar spatial vision. Comparing day-active ants and the honeybee we did not find any significant effect of locomotion on ocellar spatial vision. In M. tarsata, when the compound eyes were occluded, the amplitude of the pERG signal from the ocelli reduced by three times compared to conditions when the compound eyes were available. The signals from the compound eyes maintained the maximum contrast sensitivity of the ocelli as 13 (7.7%), and the spatial resolving power as 0.29 cpd. We conclude that ocellar spatial vison improves significantly with input from the compound eyes, with a noticeably larger improvement in contrast sensitivity than in spatial resolving power.

Ocellar spatial vision in Myrmecia ants

In addition to the compound eyes insects possess simple eyes known as ocelli. Input from the ocelli modulates optomotor responses, flight-time initiation and phototactic responses, behaviours that are predominantly mediated by the compound eyes. In this study, using pattern electroretinography (pERG), we investigated the contribution of the compound eyes to ocellar spatial vision in the diurnal Australian bull ant, Myrmecia tarsata by measuring the contrast sensitivity and spatial resolving power of the ocellar second-order neurons under various occlusion conditions. Furthermore, in four species of Myrmecia ants active at different times of the day and in European honeybee, Apis mellifera, we characterized the ocellar visual properties when both visual systems were available. Among the ants, we found that the time of activity had no significant effect on ocellar spatial vision. Comparing day-active ants and the honeybee we did not find any significant effect of locomotion on ocellar spatial vision. In M. tarsata, when the compound eyes were occluded, the amplitude of the pERG signal from the ocelli reduced by three times compared to conditions when the compound eyes were available. The signals from the compound eyes maintained the maximum contrast sensitivity of the ocelli as 13 (7.7%), and the spatial resolving power as 0.29 cpd. We conclude that ocellar spatial vison improves significantly with input from the compound eyes, with a noticeably larger improvement in contrast sensitivity than in spatial resolving power.

Retinal Response of Low Myopes during Orthokeratology Treatment

The aim of this study was to evaluate the changes in retinal activity during orthokeratology (OK) treatment in 20 myopic eyes. Pattern electroretinography (PERG) and visual evoked potential (VEP) were assessed with the RETI-port/scan21 (Roland Consult, Wiesbaden, Germany). Measurements were taken at baseline (BL) and 1 night (1N), 15 nights (15N), 30 nights (30N), and 60 nights (60N) of OK lens wear. Repeated measures analysis of variance (ANOVA) and the Friedman test were used. Twenty eyes (23.20 ± 3.46 years, 70% female) with visual acuity ≤ 0.00 logMAR in post-treatment showed that despite a slight increase in retinal and cortical response amplitude, observed with both PERG and VEP, respectively, immediately after the initial treatment, these differences found were not statistically significant during the 60 days of OK treatment, despite a statistically significant increase in N95 response with PERG. This shows that retinal and cortical visual-related electrical activity is maintained or slightly increased during OK treatment.

Myopia-26, the female-limited form of early-onset high myopia is associated with retinal ganglion cell dysfunction and primary open angle glaucoma

Background: Female-limited early-onset high myopia, also called Myopia-26 is a rare monogenic disorder characterized by severe short sightedness starting in early childhood and progressing to blindness potentially by the middle ages. Despite the X-linked locus of the mutated ARR3 gene, the disease paradoxically affects females only, with males being asymptomatic carriers. Previously, this disease has only been observed in Asian families and has not gone through detailed investigation concerning collateral symptoms or pathogenesis Results: We found a large Hungarian family displaying female-limited early-onset high myopia. Whole exome sequencing of two individuals identified a novel nonsense mutation (c.214C>T, p.Arg72*) in the ARR3 gene. We carried out basic ophthalmological testing for 18 family members, as well as detailed ophthalmological examination (intraocular pressure, axial length, fundus appearance, optical coherence tomography, visual field- and colour vision testing) and electrophysiology tests (standard and multifocal electroretinography, pattern electroretinography and visual evoked potentials) for eight individuals. We found variously impaired visual fields in four affected myopic females and a carrier male. Abnormal pattern electroretinography responses were detected in both symptomatic and carrier patients. Conclusions: This is the first description of a Caucasian family displaying Myopia-26. Pattern electroretinography implies retinal ganglion cell dysfunction present in both sexes. In conjunction with the visual field loss, this suggests the development of age-related open angle glaucoma in addition to high myopia, both attributable to the rare genetic variant of ARR3. We present two hypotheses that could potentially explain the pathomechanism of this disease.

Diagnostic applications of the "pattern" electroretinography and visual evoked potentials in the evaluation of disorders of visual pathway function in Parkinson’s disease

Background / Aim. In spite of continuous research efforts, specific laboratory, neuropsychological or neurophysiological tests for the diagnosis of Parkinson?s disease have not been established. The aims of the paper are to determine the nature and extent of visual pathway disorders on ?pattern? electroretinogram and visual evoked potentials in certain stages of Parkinson's disease. Methods. The study was carried out in a group of 60 persons of both sexes, who were suffering from idiopathic Parkinson's disease at the I-IV stage of the disease according to the Hoehn and Yahr scale, and 30 healthy persons in the control group. The battery of non-invasive neurophysiological tests was used to estimate the functional status of the visual pathway: "pattern" electroretinography (PERG) and visual evoked potentials (VEP). Results. In the early phase of PB there is a linear increase in the latency of the wave N50 of the "pattern" electroretinogram and the wave P100 of the visual evoked potentials with significant extension of the latency of the N50 and P100 waves in subsequent stages of Parkinson's disease. Diagnostic application of the "pattern" electroretinography and visual evoked potentials enables the confirmation of a disorder in the visual pathway function in Parkinson's disease. Conclusions. These neurophysiological techniques may record early changes in the function of retinal structures and the optic nerve in PD, which might be significant both from the diagnostic and therapeutic aspects.