A longitudinal study of enhanced S-Cone syndrome: Clinical and electrophysiologic assessment, progression, and genotype correlations

Session Details

Session Title: Free Paper Session 4: AMD II

Session Date/Time: Thursday 07/09/2017 | 11:00-12:30

Paper Time: 11:36

Venue: Room 111

First Author: : E.Ramos de Carvalho UK

Co Author(s): :    A. Robson   A. Webster   M. Michaelides                       

Abstract Details

Purpose:

To characterize the clinical, psychophysical, and electrophysiological phenotype of 25 patients with enhanced S-cone syndrome (ESCS) and relate the phenotype to the underlying genetic mutation.

Setting:

Moorfields Eye Hospital, London, United Kingdom

Methods:

Patients underwent ophthalmic examination and functional testing including pattern ERG, full-field ERG, and long-duration and short-wavelength stimulation. Further tests were performed in some patients, including colour contrast sensitivity (CCS), multifocal ERG, fundus autofluorescence imaging (FAI), optical coherence tomography (OCT), and fundus fluorescein angiography (FFA). Mutational screening of NR2E3 was undertaken in 21 patients.

Results:

The fundus appearance was variable, from normal to typical nummular pigment clumping at the level of the retinal pigment epithelium in older patients. Foveomacular schisis was a common finding whilst a small proportion developed macular oedema responsive to treatment with topical carbonic anhydrase inhibitors. Pattern ERG was abnormal in all patients. In all patients, ISCEV standard photopic and scotopic responses had a similar waveform, the rod-specific-ERG was undetectable and the 30-Hz flicker ERG was markedly delayed with an amplitude lower than the photopic a-wave. Most ERG responses arose from short-wavelength–sensitive mechanisms, and a majority of patients showed possible OFF-related activity. Multifocal ERG showed relative preservation of central function, but reduced responses with increased eccentricity. Mutations were identified in NR2E3 in 20 subjects.

Conclusions:

The phenotype in ESCS is variable, both in fundus appearance and in the severity of the electrophysiological abnormalities. The ERGs are dominated by short-wavelength–sensitive mechanisms. The presence, in most of the patients, of possible OFF-related ERG activity is a finding not usually associated with S-cones.

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