This article is more than 5 years old. Information may no longer be current.
Study finds benefits to correcting moderate off-axis optical errors
Peripheral visual function can be improved by correcting moderate amounts of off-axis refractive errors, according to a study recently published in Optometry & Vision Science.
Lewis and colleagues made this assessment after proving a process for ascertaining off-axis refraction that would be clinically applicable.
Researchers utilized an open-field COAS-HD VR Hartmann-Shack aberrometer (WaveFront Science) to measure central and peripheral refractive errors and Gabor patches to measure peripheral low-contrast resolution acuity in 10 participants with centrally emmetropic right eyes, as detailed in the study.
Additionally, researchers noted: "Off-axis refractive errors were calculated for a 5-mm circular pupil inscribed within the elliptical wavefront by COAS using the 'Seidel sphere' method."
Results showed that, after grouping the participants by their refractive errors, the participants with -1.00 DC of astigmatism demonstrated a decrease in resolution acuity with objectively determined off-axis refractive correction.
According to the study, the remaining groups demonstrated better resolution acuity as the degrees of astigmatism increased. The -1.25 DC group improved by 0.05 logMAR, the -1.50 group improved by 0.14 logMAR, and the -2.00 DC group improved by 0.16 logMAR.
Researchers determined that the changes observed in low-contrast resolution acuity were strongly associated with power scalar, the J180 cross-cylinder component and off-axis astigmatism. The changes were not associated with the mean spherical equivalent refractive error or J45 cross-cylinder component.
"Patients with scalar power refractive errors of 1.00 D or more (as measured by the COAS-HD VR aberrometer, in an off-axis angle within 20 degrees nasally) would benefit from an optical correction determined by the aberrometer," the authors concluded. "At 20 degrees in the nasal field, the improvement for healthy subjects corresponds approximately to one line (0.1 logMAR)."
The researchers also verified that the overall process was clinically applicable.
"The improvements in visual function produced under idealized laboratory setting with psychophysical through-focus procedure can be realized in a more clinical setting by using the Zernike refraction of a commercial wavefront sensor," the authors wrote. "The main advantages of using a wavefront sensor are that the refraction procedure is much faster than psychophysical through-focus procedures and does not rely on subjective responses; it should be kept in mind that the evaluation of peripheral resolution acuity is a very demanding task and multiple psychophysical procedures might give inconsistent results owing to fatigue, especially in elderly subjects."
Disclosures: The authors have no relevant financial disclosures.