Purchase this article with an account.
Debananda Padhy, Aparna Rao; A modified visual field index to measure the central visual function in eyes with fixation involvement.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3903.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To evaluate performance of a modified visual field index (mVFI) using central two rings (9 degree) with additional 4 threshold points on each hemifield on a 24-2 visual field (24-2+8) in eyes with central fixation involvement.
Thirty-five eyes of 35 moderate glaucoma (Mean deviation, MD -6 to -12dB) patients with central fixation involvement were included.For difference of 10 percent between the two methods power of 80 and alpha error of 0.05 the sample size was calculated to be 35. Eyes with posterior subcapsular cataract and visual acuity <20/40 or retinal lesions were excluded. Four points (10, 50 and -10 and -50) were added in each superior and inferior hemifield in the central inner most ring 1 (3 degree spaced grid) and 2 (6 degree spaced grid) on 24-2 test(figure 1) and thresholds for these points calculated from the adjacent points. The mVFI was calculated as for conventional index (cVFI) previously described after applying eccentricity based weightage for all points. This was compared to MD on 10-2, thresholds of points in ring 1 and 2 in 10-2 program(figure 2) and with points with p<0.01 on 24-2 and 10-2 tests.
The mVFI (66±3.1%) differed significantly from cVFI (74±8.05) with the difference between the two ranging from -18 to +6% in eyes with fixation involvement. The mVFI correlated with thresholds of points in ring 1(r=0.5, p=0.001) and 2 of 10-2 (r=0.6, p=0.001) while no correlation of cVFI with 10-2 points was observed (p =0.08 and 0.09, respectively). The difference between mVFI and cVFI was maximally influenced (R2=56.8%) by number of points with p<0.01 on 24-2 (p=0.02) and average threshold of points in ring 2 (p=0.01) of 10-2.
The mVFI with addition of 4 points in each hemifield of 24-2 test (24-2+8 program) may be more accurate and true measure of central visual function than cVFI in eyes with fixation involvement. The number of depressed points in the centre may influence greater deviation from true function in these eyes when using cVFI in these eyes.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
This PDF is available to Subscribers Only