Effect of operator and optical defocus on the variability of pattern electroretinogram optimized for glaucoma detection (PERGLA).
OBJECTIVE
To evaluate the effect of operator and optical defocus on the variability of pattern electroretinogram optimized for glaucoma detection (PERGLA).


METHODS
Two different operators obtained 2 PERGLA recordings each from 10 healthy participants (5 women, mean age 32.1+/-10.3 y). In addition, one of the operators obtained recordings in which corrective lenses of various diopters (+/-0.5, +/-1, +/-2, and +/-3) were used to generate optical defocus in both eyes. The effect of operator on PERGLA amplitude and phase variability was determined using a single nested variance components' analysis model and by using Bland-Altman plots. One-way analysis of variance (ANOVA) was used to determine the effect of optical defocus on amplitude and phase.


RESULTS
Differences in measurements between operators accounted for approximately 26.6% and 18.2% of the total variance for amplitude and phase, respectively. Results were confirmed by the use of Bland-Altman plots. ANOVA identified a significant effect of defocus on mean amplitude (F=2.65, P=0.01), but not phase (F=1.02, P=0.42).


CONCLUSIONS
Measurements obtained by different operators can result in significant differences in PERGLA amplitude. In addition, although optical defocus leads to a decrease in PERGLA amplitude by reducing visual acuity, this can be avoided by obtaining J1 or better vision before testing.
Vizzeri
Gianmarco
G
Department of Ophthalmology, Hamilton Glaucoma Center, University of California, San Diego, La Jolla, CA 92037-0946, USA.
Tafreshi
Ali
A
Weinreb
Robert N
RN
Bowd
Christopher
C
D000328:Adult; D004596:Electroretinography / Q000379:methods*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D015588:Observer Variation; D010364:Pattern Recognition, Visual; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D014065:Tonometry, Ocular