Abstract
Purpose:
The aim of the study was to investigate the effect of horizontal and vertical meridional refractive defocus on amplitude and implicit time of P1 in multifocal electroretinogram (mfERG) at three different areas of the retina.
Methods:
Six combinations of astigmatism were induced by soft toric contact lenses, C1 (plano/-1.00 × 180), C2 (plano /-2.00 × 180), C3 (plano /-3.00 × 180), C4 (plano /-1.00 × 90), C5 (plano /-2.00 × 90), C6 (plano /-3.00 × 90), in the fully dilated pupil condition on ten young healthy emmetropic subjects. The amplitude and implicit time of P1 were evaluated at three difference locations of the retina, namely area A (1 hexagon: 19.8 deg2 at 0° viewing angle), area B (20 hexagons: 42.9 deg2 at 17.2° of viewing angle) and area C (20 hexagons: 47.9 deg2 at 15.4° viewing angle). The horizontal defocus was gathered from C1, C2 and C3 whereas C4, C5 and C6 simulated the vertical defocus. The effects of horizontal and vertical defocus among the same cylindrical refractive power were measured in the areas of A, B and C.
Results:
From the comparison, C1 and C4, C2 and C5 as well as C3 and C6 showed insignificant value between horizontal and vertical defocus of the focal lines for the same cylindrical power in the three difference retinal areas, where p > 0.05.
Conclusions:
The effects of horizontal defocus and vertical defocus below or equal to -3.00 DC did not influence the reading of P1 amplitude and implicit time of mfERG.
Keywords: 510 electroretinography: non-clinical •
428 astigmatism •
465 clinical (human) or epidemiologic studies: systems/equipment/techniques