Ganglioside administration in retinitis pigmentosa

Systematic Review of Randomized Clinical Trials on Safety and Efficacy of Pharmacological and Nonpharmacological Treatments for Retinitis Pigmentosa

Aims. Several treatments have been proposed to slow down progression of Retinitis pigmentosa (RP), a hereditary retinal degenerative condition leading to severe visual impairment. The aim of this study is to systematically review data from randomized clinical trials (RCTs) evaluating safety and efficacy of medical interventions for the treatment of RP. Methods. Randomized clinical trials on medical treatments for syndromic and nonsyndromic RP published up to December 2014 were included in the review. Visual acuity, visual field, electroretinogram, and adverse events were used as outcome measures. Results. The 19 RCTs included in this systematic review included trials on hyperbaric oxygen delivery, topical brimonidine tartrate, vitamins, docosahexaenoic acid, gangliosides, lutein, oral nilvadipine, ciliary neurotrophic factor, and valproic acid. All treatments proved safe but did not show significant benefit on visual function. Long term supplementation with vitamin A showed a significantly slower decline rate in electroretinogram amplitude. Conclusions. Although all medical treatments for RP appear safe, evidence emerging from RCTs is limited since they do not present comparable results suitable for quantitative statistical analysis. The limited number of RCTs, the poor clinical results, and the heterogeneity among studies negatively influence the strength of recommendations for the long term management of RP patients.

Low-noise electroretinogram recording techniques in retinitis pigmentosa

The achievement of a sharp retinal signal depends on many factors, particularly the stability of the electrodes on the corneal surface, the maximal reduction of electrical and electromagnetic disturbances and the avoidance of the noise caused by events that are synchronous with the stimulation. The availability of a low-noise recording system becomes critical in the detection of the electroretinogram in patients with retinitis pigmentosa. We studied an electroretinographic recording technique specifically designed to enhance the signal-to-noise ratio in patients with retinitis pigmentosa. The main features of the method are a membrane suction pump connected to the corneal electrodes to improve contact lens stability on the corneal surface, and a differential derivation system to record the signal. One corneal electrode is used as the recording electrode, while the other, acting as the reference electrode, is covered during full-field ganzfeld stimulation. In addition, computerized averaging and signal postrecording analyses were performed on 100 iterations. The methods described here resulted in a sharp reduction in the number of undetectable electroretinograms in our case material (28.8%). This investigation demonstrates that some of the undetectable signals reported in the literature may be due to noisy recording methods rather than to actually extinguished retinal responses.