Small-field perimetry applied to different types of retinitis pigmentosa: preliminary results

Abstract

Purpose: To measure the sensitivity of small retinal areas by reducing the influence of the adaptation state of the rest of the retina. To assess the functional behaviour of the retina of several patients affected by different types of retinitis pigmentosa (RP).Methods: A prospective study was performed. Five eyes of patients with retinal diseases and different genetic mutations were studied at the University of Valladolid: three typical RP, one cone rod dystrophy (CRD) and one Bardet-Biedl syndrome (BBS). One of the RP patients was analysed again 18 months after the first measurements. A two-maxwellian view optical arrangement was used to measure the luminance thresholds of retinal areas 1 deg sized under dark and low photopic adaptation conditions. Linear regression fits of these thresholds vs. eccentricity were used to compare the patients' sensitivity with the control group. Results:The slopes of the linear fits of the other typical RP patients were higher than those of the control group. The parameters of the linear fits of the RP patient measured twice changed significantly with time. Conclusions:The designed psychophysical method provides, in all cases, coherent results with the expected ones according to the genetic mutation of the patients. The technique seems to be very sensitive to changes in the retinal response. It can be easily incorporated as a technical complement to the traditional perimetry.