Purpose:
To correlate the estimated visual acuity obtained from SD-tVEP and ETDRS in individuals with AMD (age related macula degeneration).
Methods:
SD-tVEP was performed in 19 patients with AMD. One eye was selected randomly. Test duration was 20 seconds/eye. Synchronized single-channel SD-tVEP were recorded using a Diopsys NOVA System (Diopsys, Inc., Pine Brook, New Jersey, USA), which generated a time series of 240 data points per analysis window. Eight checkerboard patterns were used in the study ranging from 3.75’ to 466’ in octave steps. The Michelson contrast was set to 100 percent. The following information was identified from the VEPs N75-P100-N135 complex: Delta P100-N75 amplitude. Acuity was determined by ETDRS. The acuity was also calculated by using the VEPs Delta P100-N75 amplitude for each pattern. The amplitudes were plotted against the arc minutes of each pattern. A linear regression was performed on the amplitudes. The point where the regression crossed the x-axis is the check size in arc minutes that the subject would not elicit a VEP. The Pearson Coefficient was calculated comparing the ETDRS and SD-tVEP acuity results.
Results:
Mean age of the AMD patients was 77.2 ±7.7 yrs. The results from the ETDRS and the SD-tVEP had a high correlation (p = .922) (scatter plot). Two patients with counting finger acuity and one with hand motion were excluded in the chart to show linearity; however, they were included in the correlation calculation.
Conclusions:
There is strong correlation between visual acuity obtained from SD-tVEP and ETDRS. The objective assessment of visual function with SD-tVEP may prove to be useful is assessing response to treatments in patients with AMD.
Keywords: age-related macular degeneration • visual acuity • electrophysiology: clinical