Photostress Recovery Time Among Nigerians

Abstract

Visual impairment may result from a deficiency of the retinal pigment epithelium or macula. Macula photostress test (MPST) is a quantitative estimation of the functional capability and performance reserve of the photoreceptive elements of the macula/retina. The purpose of this study was to determine the Photostress Recovery Time (PSRT) of different age groups in a sample of healthy subjects. Two hundred subjectswithanage range of 11years to70years (meanage of 33.30±12.74years)were usedfor this study. All the subjects had clear ocularmedia, normal appearance of the fundus, and visual acuityof 6/6 or better inthe testedeye. Prior toexperimentationeachsubjectwas adaptedtothe ambient roomlightingfor about 5mins. The upperlid of the eye to be tested was held firmly while a penlight was shone into the eye for about 10 seconds, PRSTwas assessed immediately after 10 seconds by asking the subjects to read at least three letters on the V.Aline immediately above the subject's best acuity line. The testing order of subjects in different age groups was randomized. Results indicated that the PSRT distribution in the sample population was found to be positively skewed with a mean of PSRTranging from10.34seconds to 46.98 seconds for an age range of 11 years to 70 years. Clinically males had slightly higher PSRT when compared to females. There was a positive relationship between age and PSRT which was highly significant (r =0.96) with a linear regression equation of PSRT=0.785+ 0.60xage. Themean increase in PSRT across consecutive age groups investigated was 27.46%. Males demonstrated a much sharper and larger increase in PSRT across consecutive age groups when compared to the females at all ages investigated except in the presbyopic age group. This study attempts to establish age related PSRTscores among healthy Nigerians in order to provide a quick reference in comparing normal physiological PSRT values and PSRTvalues arising from impending retinal/macular lesions.

Keywords: Macular photostress test, Retinal photoreceptors, Retinal pigment epithelium