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Subjective refraction of the peripheral field using contrast detection acuity
Y Z Wang1, L N Thibos, N Lopez
1School of Optometry, Indiana University, Bloomington 47405, USA.
Journal of the American Optometric Association
|October 1, 1996
Summary
Subjective refraction in peripheral vision is feasible using contrast detection. This method accurately estimates refractive error in the periphery, impacting standard visual field testing.
Area of Science:
- Ophthalmology
- Vision Science
- Optometry
Background:
- Peripheral resolution acuity is generally unaffected by uncorrected refractive error.
- However, contrast detection in peripheral vision is limited by optical factors.
- This suggests subjective refraction is possible in the periphery using contrast detection.
Purpose of the Study:
- To determine if subjective refraction can be performed in the peripheral visual field.
- To assess the feasibility of using contrast detection for peripheral subjective refraction.
- To compare subjective refraction estimates with objective measurements.
Main Methods:
- Contrast detection acuities for gratings were measured using a two-interval forced-choice paradigm with various trial lenses.
- Subjective refraction estimates were determined by lens powers that maximized contrast detection acuity.
- Objective refractions were obtained via retinoscopy and autorefractometry for comparison.
Main Results:
- Contrast detection acuity significantly varied with lens power across all tested retinal locations.
- A one-diopter defocus reduced detection acuity by approximately 50% at 20 degrees eccentricity.
- Objective refraction methods generally agreed with subjective measurements.
Conclusions:
- Contrast detection acuity in the peripheral visual field is sensitive to refractive blur.
- This confirms the feasibility of subjective refraction in the periphery for contrast-based tasks.
- Standard perimetry, relying on contrast detection, may be influenced by uncorrected peripheral refractive errors.