Electroretinography and optical coherence tomography reveal abnormal post-photoreceptoral activity and altered retinal lamination in patients with enhanced S-cone syndrome.

PURPOSE: To compare functional abnormalities of enhanced S-cone syndrome (ESCS), as examined using standard and extended electroretinography (ERG), with structural findings and retinal architecture obtained by spectral domain optical coherence tomography (SD-OCT). METHODS: Four patients with ESCS underwent standard full-field and multifocal ERGs, with extended S-cone and ON/OFF ERG protocols also performed. SD-OCT was also carried out, and longitudinal reflectivity profiles (LRPs) were calculated for the perifoveolar retina. RESULTS: All four patients exhibited pathognomonic full-field ERG findings for ESCS, with delayed responses of similar waveforms to the same intensity flash under both scotopic and photopic conditions. The amplitudes of the full-field ERGs showed considerable variation between patients, which were not related to the extent of the visual field defects. Multifocal ERGs reflected preserved central function in eyes with good visual acuity (Snellen visual acuity >0.7). The ERGs to S-cone-specific stimulation confirmed the expected predominant activity of the S-cone system in all four patients. The ON/OFF ERG recordings revealed abnormal presence of both ON-response and OFF-response activities in three patients; the remaining patient showed only OFF-response activity. SD-OCT showed a significantly thickened outer nuclear layer in all four patients, as obtained by LRP analysis. Furthermore, in the patient with selective preservation of the OFF-response activity, LRP showed reduced numbers of hyper-reflectivity sub-peaks in the inner plexiform layer. CONCLUSION: Patients with ESCS show characteristic full-field ERG waveform abnormality, predominance of S-cone ERG activity, and thickening of the outer nuclear layer on SD-OCT. Moreover, they can also show abnormal post-photoreceptor connectivity through S-cone-related OFF-bipolar cell activity.

Optic neuritis in children--clinical and electrophysiological follow-up.

Optic neuritis (ON) in children usually presents with visual loss, relative afferent pupillary defect (RAPD), abnormal optic disc appearance, defects of visual field and colour vision, as well as with abnormalities of visual evoked potentials (VEP). Both, clinical and VEP parameters, improve after the attack; the time until recovery, however, is as yet unknown. The aim of this study was to follow-up children with ON for 1 year and to determine clinical and VEP recovery. Twelve children (six with bilateral, six with unilateral ON) were studied in the acute phase and systematically followed-up for 1 year. The results show that initially, visual acuity was diminished in all eyes, while after 1 year, in only 14% of them. Optic disc appearance was abnormal in 83.3% of the eyes in the acute phase, and in 85% after 1 year. At the disease onset RAPD could be detected in 67%, visual field defects in 58.5%, and colour vision defects in 50% of eyes, but none of these abnormalities persisted in any eye until the end of study. VEP were abnormal in 83% of eyes in the acute phase and in 56% at the final follow-up (at 6 or 12 months). VEP normalization, when occurred, was mostly observed during the first 6 months. Complete clinical and VEP recovery was observed in three children. Both, clinical and electrophysiological recovery in children with ON were relatively substantial and fast within the first year. VEP improvement may indicate better prognosis.

Visual electrophysiology in children with tumours affecting the visual pathway. Case reports.

In 9 children (8-14 years of age) with orbital, suprasellar or postchiasmal tumours, visual loss was studied by visual electrophysiology in relation to ophthalmologic and neuroimaging findings. Pattern electroretinography (PERG) and pattern visual evoked potentials (PVEP) to full and half-field pattern-reversal stimulation were recorded and PERG and PVEP changes were related to the tumour location. PERG wave P50 attenuation was found associated with the central retinal dysfunction in the child with orbital rhabdomyosarcoma; PVEP wave P100 delay was associated with the optic nerve dysfunction in a child with retrobulbar chondrosarcoma and in a child with optic nerve glioma; PVEP wave P100 asymmetry was associated with the crossed fibers dysfunction in a child with hypothalamic germinoma, and PVEP wave P100 uncrossed asymmetry was associated with postchiasmal dysfunction in children with postchiasmal tumours (one with pilocytic astrocytoma and two with angioma). On the other hand, normal PERG suggested that there was no central retinal dysfunction in a child with pleomorphic adenoma of the lacrimal gland, and normal PVEP to full and half-field stimulation excluded visual pathway dysfunction at the chiasm in a child with suprasellar arachnoidal cyst. Follow-up was useful in indicating whether visual dysfunction was progressive or not. We conclude that PERG and PVEP findings contributed to understanding whether the dysfunction originated was at the retina, in the optic nerve, chiasm or postchiasmal pathway.

ERG and VEP follow-up study in children with Leber's congenital amaurosis.

PURPOSE: Our prospective clinical and electrophysiological study of children suspected of Leber's congenital amaurosis (LCA) was aimed to follow-up the course of their visual dysfunction. METHODS: Electroretinography (ERG) and visual evoked potentials (VEP) to white flash stimulation were simultaneously recorded in 9 children at least twice. RESULTS: The first flash ERG and flash VEP recordings were performed when children were 3-17 months old (mean age 7.6 months). Flash ERG was not recordable in 8 children; flash VEP to binocular stimulation could not be detected in 3, was delayed in 2, attenuated in 2, both attenuated and delayed in 1, and without evident abnormality in 1 of the 9 children. On the last examination (mean age 33.8 months) flash VEP activity was recordable in all children, while flash ERG was recordable in 1. Electrophysiological follow-up (mean duration 26.2 months) showed no deterioration of flash VEP in 8 children. CONCLUSION: In children of LCA simultaneous recording of flash ERG and flash VEP in alert children was helpful to indicate the nature of the visual problem for diagnostic and follow-up purposes.

Electrophysiologic evaluation of the visual pathway in children. Case reports.

Clinical findings and results of electrophysiologic evaluation of the visual pathway were studied in seven children ranging in age from 10 months to 13 years. Using skin electrodes for electroretinographic and visual evoked potential testing, we obtained reliable results without sedation or pupil dilation. The half-field stimulation was indispensable for localizing lesions along the visual pathway and thus for specific diagnosis.

Pattern electroretinogram recorded by skin electrodes in early ocular hypertension and glaucoma.

Diagnostic value of transient pattern electroretinogram (PERG), recorded by skin electrodes, was compared with Goldmann perimetry in cases of ocular hypertension and glaucoma. According to the assumption that the PERG mostly reflects activity of the retinal ganglion cells, and histological evidence that 30-50% atrophy of the retinal ganglion cells is necessary to cause defects in visual field, we wanted to assess if i) this method could be more sensitive in detecting early glaucomatous damage than routine Goldmann perimetry in eyes with normal or only borderline elevated intraocular pressure in the time of PERG recording (first group of patients), and ii) how the PERG amplitude corresponds to ganglion cell loss, expected in the eyes with already detectable initial glaucomatous visual field defects, according to Goldmann II/2 isopter, with normal or borderline elevated intraocular pressure in the time of PERG recording (second group). In the group with no visual field defects subnormal amplitude of the major positive component of the PERG, N1-P1, was detected in three of 30 eyes (10%), while in the group with initial visual field defects N1-P1 amplitude was subnormal in 6 of 11 eyes (54%). The amplitude of the major negative PERG component, P1-N2, was found normal in all eyes of the first group and subnormal in 5 eyes (45%) of the second group.