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Population norms for frequency doubling perimetry with uncorrected refractive error.
Sathyamangalam Ve Ramesh1, Ronnie George, Premal M Soni
1Glaucoma Project, Vision Research Foundation, Sankara Nethralaya, 18 College Road, Chennai 600006, India.
Summary
Uncorrected refractive errors do not significantly affect visual field threshold estimation using frequency doubling perimetry (FDP). High within-subject variability in FDP testing likely explains these findings in normal subjects.
Area of Science:
- Ophthalmology
- Visual Psychophysics
- Glaucoma Research
Background:
- Refractive error is common and can influence visual function tests.
- Frequency Doubling Perimetry (FDP) is used to assess visual fields, particularly in glaucoma detection.
- Understanding the impact of uncorrected refractive error on FDP is crucial for accurate threshold estimation.
Purpose of the Study:
- To compare the effect of uncorrected refractive error on threshold estimation using Frequency Doubling Perimetry (FDP) full-threshold N-30.
- To evaluate differences between ammetropic (uncorrected refractive error) and emmetropic (normal vision) subjects using FDP parameters.
- To assess both between-subject and within-subject effects of refractive error on FDP results.
Main Methods:
- 1,299 subjects from the Chennai Glaucoma Study were analyzed.
- Normal subjects with refractive errors within +/-7 D were stratified into groups and compared to emmetropic controls.
- Frequency Doubling Perimetry (FDP) full-threshold N-30 test was performed, analyzing parameters like mean deviation and pattern standard deviation.
Main Results:
- No statistically significant differences were found in mean deviation or pattern standard deviation between refractive error groups and emmetropes.
- FDP parameters showed no significant differences in between-group or within-group comparisons.
- Variability of FDP sensitivity was noted, with slight reductions when spectacles were used for correction.
Conclusions:
- Uncorrected refractive errors do not significantly alter FDP threshold estimation in normal subjects.
- Both between-subject and within-subject comparisons revealed no significant differences in FDP parameters.
- High within-subject variability of FDP is suggested as a reason for the lack of significant findings.
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