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Michael K. Smolek; Age-Related Macular Degeneration Screening Based on Bilateral Fundus Perimetry. Invest. Ophthalmol. Vis. Sci. 2011;52(14):122.
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© ARVO (1962-2015); The Authors (2016-present)
There are few simple methods available for reliably screening age-related macular degeneration (AMD). Visual acuity tests lack specificity and the widely-used Amsler grid test has been shown to be insensitive to early AMD. This study investigated a novel method of AMD screening based on comparing the light sensitivity of corresponding macular points of fellow eyes as measured with a fundus perimeter (microperimeter). To understand the outcome of the study, the loss of unilateral and bilateral symmetry seen in the graphical patterns of macular sensitivity of fellow eyes with the progression of AMD was also investigated.
Fundus perimetry with a macular integrity assessment device (MAIA; CenterVue, SpA; Padova, Italy) was performed on 31 subjects with clinically-diagnosed normal eyes and 31 subjects with one or both eyes diagnosed as having early or intermediate AMD. Bilateral fundus perimetry was performed to acquire stimulus sensitivity values measured in decibels (dB) from mirror-image corresponding points of right and left eye maculae. Data from both eyes were transcribed to a spreadsheet for numerical analysis. The sensitivity difference in dB at each corresponding stimulus point was calculated, after which the mean sensitivity difference and standard deviation (SD) of the mean for all stimulus point differences were analyzed for a statistically significant difference between the normal and AMD groups.
The mean sensitivity difference between groups was not significant at the P<0.05 level using Student’s t-test. However, the SD of the mean sensitivity difference of corresponding points in the right and left maculae was highly significant between the AMD and normal groups (5.80 ±0.78 dB versus 2.70 ±0.05 dB, respectively; P<0.001). Screening for AMD using the SD of the mean sensitivity difference had a sensitivity of 98% and specificity was 100%. Graphical contour plots of bilateral sensitivity difference illustrated the effects of AMD progression and why bilateral variance increases.
Screening for early AMD with fundus perimetry was highly successful when the variance in the sensitivity of corresponding points for both eyes was compared. This AMD screening method appears to be successful because normal eyes tend to exhibit a bilaterally symmetric pattern of macular sensitivity that is easily disrupted when one or both eyes acquire localized sensitivity loss due to AMD. New generation fundus perimeters are designed for rapid screening in non-clinical venues, and may replace or supplement Amsler grid testing for AMD.
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