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Neil F. Notaroberto, Michael K. Smolek, Lauren E. Fereday; What Accounts for Differences in Fellow Eye Retinal Sensitivity?. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4828.
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© ARVO (1962-2015); The Authors (2016-present)
Higher sensitivity has been seen in left (OS) eyes in both normal (NRM) and moderate age-related macular degeneration (AMD) during microperimetry. This study evaluates the statistical significance of the finding.
Patient data was acquired by informed consent. High-density MAIA microperimetry (Centervue SpA, Padua, Italy) recorded retinal sensitivity in decibels (dB) from 60 corresponding points in NRM eyes (n = 254 OD, 240 OS) and AMD eyes (n = 68 OD, 87 OS). Mean sensitivity and variance at each stimulus point were compared for OD and OS by a t-test. The mean of the means of all 60 stimuli were also compared. Significance was set at p ≤0.05.
NRM data showed that 19/60 points (31.7%) were significantly more sensitive in OS eyes, while only 1/60 (1.7%) were significantly more sensitive in OD eyes. When all 60 stimuli were averaged for NRM, the mean OS sensitivity was slightly, but significantly greater than OD (29.95 ±0.54 vs 29.69 ±0.52 dB; p = 0.008, t-test). AMD data showed that 12/60 (20%) points were significantly more sensitive in OS eyes, while 0% of OD eyes were more sensitive. When all 60 stimuli values were averaged for AMD, the mean OS sensitivity was significantly greater than the OD sensitivity (22.42 ±0.62 vs 20.97 ±0.64 dB; p <0.001, t-test).
Most corresponding points are not significantly different, but when they are different, the OS eye is more sensitive. Several possible explanations exist: 1) OS eyes are inherently more sensitive, which seems unlikely; 2) the effects are due to learning; or 3) dark adaptation is occurring during the test making the second eye appear more sensitive. If the photoreceptors of both eyes are not fully adapted to a lower examination room illumination at the start of the test, the first eye tested will appear as less sensitive than the second eye, which should be more dark adapted due to the passage of time. The common convention of testing the OD eye first may thus cause the OD eyes to appear as slightly less sensitive than OS eyes. While this small difference is not clinically significant for individual cases and can be ignored, it may be significant in some types of group research studies. Researchers should monitor the subject's dark adaptation, randomize OD and OS recording, and track first and second eye data separately.
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