Purchase this article with an account.
LM Ventura, D Lemus, RK Parrish, V Porciatti; Screening for Glaucoma With a Simplified Version of the Pattern ERG Called PERGLA: 49% of Glaucoma Suspects With Abnormal Disk and Normal IOP and Visual Field Have an Abnormal Response . Invest. Ophthalmol. Vis. Sci. 2002;43(13):306.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To screen for early Pattern ERG abnormalities in subjects suspected of having glaucoma using a simplified, non-invasive and automated technique called PERGLA. Methods: The PERGLA is recorded simultaneously from both eyes by means of skin electrodes on the lower eyelids, in response to horizontal gratings (1.7 c/d, 25 deg circular field, 95% contrast, 100 cd/sqm mean luminance), alternating at 8.14 Hz. The test lasts 3 minutes (two blocks of 1.5 minutes each) and subjects are allowed to blink freely. The PERGLA amplitude and phase (latency) are automatically evaluated by Discrete Fourier Transform and compared with a database of age-corrected, normative values (n=80 eyes). Amplitude and latency are expressed as deviations from normal in SD units. One hundred and sixty one eyes of 81 patients with no ocular diseases other than glaucoma were tested. Inclusion criteria were: normal visual acuity, IOP < 21 mm Hg and Humphrey visual field Mean Defect (MD)< 3dB, in the presence of increased cupping (vertical C/D ≷ 0.5, or vertical C/D ≷ 0.4 plus at least one of the following: asymmetry ≷ 0.2, disk notching, disk splinter hemorrages, or positive family history). Results: The response amplitude was lower than 2 SDs from normal average in 45/161 eyes (28%) and the latency was longer than 2 SDs in 19/161 eyes (12%). Responses abnormal for both amplitude and latency were 10/161 (6%). Interocular amplitude and latency asymmetries exceeded 2 SDs in 15% and 3% of patients, respectively. Overall, patients with an abnormality in either amplitude/latency or interocular asymmetry were 40/81 (49%). Latency abnormalities increased significantly with age (r squared =0.4). There was no obvious association between amplitude losses and the amount of cupping; however, there was a borderline correlation between amplitude asymmetry and C/D asymmetry (p=0.078). Conclusion: The PERGLA technique detected abnormal responses in 49% of glaucoma suspects with increased cup/disk ratios and normal IOP and visual fields. At six month intervals, we are repeating the PERGLA and visual fields in all patients to determine possible glaucomatous progression.
This PDF is available to Subscribers Only