Abstract
Purpose :
To examine the structure-function relationship between retinal thickness and visibility of light and dark perimetric stimuli in eccentric quadrants of myopic eyes.
Methods :
Eighteen contact-lens corrected eyes of 18 human subjects (25.83 years; ± 2.77), ranging in refractive error from plano to -9.50 diopters, were tested at 8 Michelson contrast levels (5-20%) out to 30° from fixation. Each test included 579 trials at 92 locations, repeated 3 times for light and dark stimuli.
Stimuli, dark and light squares scaled for eccentricity, were presented within a head-mounted display (HTC VIVE Pro Eye) with a maximum luminance of 110 cd/m2. Fixation was restricted to a central 2.5° radius. The percentage of incorrect responses (% errors) were measured across the entire visual field and of 3 annual eccentricities 5-10°, 15-20°, and 25-30°.
A wide-field 55° Spectralis OCT measured peripheral total retinal thickness (TRT) at 20°. Mean sensitivity (MS) was measured using 30-2 SITA-standard Humphrey visual fields. ON-OFF % errors, MS, and TRT underwent quadrant specific analysis in the superonasal (SN), superotemporal (ST), inferonasal (IN), and inferotemporal (IT) quadrants of visual space. Peripheral refractive error (PRE) and axial length (AL) were measured with a Grand Seiko WAM-5500 autorefractor and Haag Streit Biometer Lenstar LS-900 respectively.
Results :
At 20°eccentricity, the TRT ranged from 265.44 ± 18.85 microns in the IT quadrant to 213.28 ± 11.34 microns in the SN quadrant (p = 3.81 x 10-7,Wilcoxon test for IT vs SN comparison). A significant relationship existed between TRT and both ON-OFF % error and MS. The IT quadrant was associated with the lowest % errors (6.45 ± 6.56) and highest MS (30.9 ± 1.08 dB), whereas the SN quadrant was associated with the highest % errors (22.77 ± 15.93, p=8.91 x 10-9 for IT vs SN comparison) and lowest MS (29.43 ± 1.34, p=0.0020 for IT vs SN comparison). A mild significant negative correlation exists between MS and % errors only between 25-30° (r = -0.38, p=0.0214). MS was not significantly correlated with AL (r= 0.19, p=0.4513) or RE (r=0.15, p=0.5412) at 25-30°. Average spherical equivalent PRE was -0.10 D ± 0.39.
Conclusions :
Regional differences in TRT are associated with different ON-OFF % error rate and MS in myopic patients.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.