Abstract
Purpose :
As myopic maculopathy is a major cause of blindness in much of the world, early risk assessment and clinical detection for highly myopic patients would seem prudent. Visual field testing of the central 20 degrees can reveal valuable information about the foveal and macular function. The objective of this observational clinical study is to evaluate central visual field (VF) sensitivities in relation to the myopic maculopathy risk factors of degree of myopia, axial lengths (AL), and age.
Methods :
11 myopic subjects currently wearing soft contact lens powers (CLP) -1.00 to -12.00 diopters (D) between the ages of 18 and 59 were recruited. Subjects were excluded if they had prior diagnoses of maculopathy or systemic conditions that could affect refractive error. Subjective manifest refraction was used to verify refractive errors and calculate vertex and test distance corrected CLP for the VF assessment using the OCULUS EasyField perimeter. AL measurements were obtained with a ZEISS IOLMaster-500 optical biometer. The primary outcome measure was to compare the mean deviation (MD) on central 10-2 threshold visual fields between low myopia and high myopia using unpaired t-tests with a cut point of -6.00 D.
Results :
There were 5 subjects in the high myopic group (HMG) and 6 in the low myopic group (LMG). The spherical equivalent of the HMG was -10.47±1.78 D and the LMG was -3.94±1.86 D. Axial length of the HMG was 27.75±0.87 mm and the LMG was 25.66±0.72 mm. All subjects showed with the rule corneal toricity with the HMG having steeper K values and more corneal toricity than the LMG. Self-reported age of first spectacle prescription was age 7.0 for the HMG and age 10.5 for the LMG (p = 0.025). The mean deviation on 10-2 threshold VF in the HMG was 0.48±0.87 dB and 1.09±0.61 dB in the LMG (p = 0.238).
Conclusions :
While the mean deviation for the HMG was lower than the LMG, it did not reach statistical significance. The normative database of the perimeter should control for age related decreased sensitivity so any other difference would likely be due to anatomical and/or physiological differences as it relates to myopia severity. Future work entails testing 10-2 threshold visual fields in a larger sample and exploring other factors such as retinal and choroidal thickness in relation to contrast sensitivity or other visual function beyond visual acuity.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.