Abstract:
To establish normative values for fixation stability and macular sensitivity to light in normal subjects using a liquid crystal display (LCD) perimeter. To establish a relationship of fixation stability and retinal sensitivity to age, gender and race in the study population.
Full threshold perimetry of the central 12° of the retina (macula) was tested prospectively using 16 points by LCD perimeter (MP 1, Nidek Technologies, Italy.) after institutional review board approval. The MP 1 simultaneously documents the fixation stability of the retina during retinal sensitivity testing. Subjects with systemic illnesses and on any systemic medications were excluded from the study. Only eyes with best–corrected visual acuity of 20/20 were included. The relationship of light sensitivity with age, sex and race was evaluated.
Perimetry was performed on 66 eyes of 37 healthy subjects after informed consent. Total mean sensitivity of the study population was 18.33 dB (range 16.0 to 19.25). Eyes tested had refractive errors between + 2.00 to – 3.00 diopters. Mean sensitivity was statistically higher in subjects less than 40 years as compared to patients greater than 40 years at the 2° (p = 0.031), 4° (p= 0.033), and 6° (p = 0.011) of the central retina. No difference in sensitivity was found between gender or race. There was no difference between age, race and gender for the fixation stability.
LCD microperimeter appears to be a reliable tool to measure retinal sensitivity. Even among normal healthy subjects, light sensitivity decreases with increasing age. Retinal light sensitivity greater or equal to 16.0 dB can be consider normal.
Keywords: perimetry • macula/fovea • retina