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Andre Messias, Katharina Messias, Rafael Saran Arcieri, Fabiano Sakamoto, Vinicius M Castro, Rodrigo Jorge; Chromatic Full-field Stimulus Threshold (FST) in Proliferative Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2014;55(13):335. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To describe chromatic full-field stimulus threshold (FST) outcomes in proliferative diabetic retinopathy (PDR) and their relationship with electroretinography (ERG).
Data from 24 patients with PDR (n=31 eyes; 56 ± 10 years of age; 50% male) were analyzed. Patients were submitted to measurement of best-corrected visual acuity (BCVA), and full field Electroretinography (ERG), according to ISCEV was performed to determine a- and b-wave amplitude and implicit time for dark-adapted rod (0.01 cd.s/m2), combined response (CR: 3.0 cd.s/m2) and light-adapted cone (3.0 cd.s/m2) and 30 Hz flicker (3.0 cd.s/m2). FST was psychophysically determined before ERG recordings, after 25 minutes dark adaptation, using Espion E2 system with the ColorDome LED full-field stimulator (Diagnosys LLC, Lowell, MA), first using red (635 to 638 nm), then blue (465 to 470 nm), and then white (6500 K) stimulus, with 5 minutes inter-session interval. Normal subjects were evaluated to serve as controls (n=20).
Mean ± SE patients’ FST was significantly higher than (controls’) for white: -28.1 ± 1.3 dB (-42.3 ± 0.7 dB; ANOVA P<0.001), blue: -33.9 ± 1.7 dB (-48.9 ± 0.7 dB; P<0.001); and red: -14.6 ± 0.9 dB (-25.4 ± 0.6 dB; P<0.001). Of interest, only 7 (23%), 6 (19%) and 11 (35%) eyes were above the controls’ 5% quantile. Mean BCVA was 0.40 ± 0.05 logMAR (range: 20/20 to 20/200), and was not significantly correlated to FST of any color. There was moderate (r ≥ 0.5) significant (P<0.05) correlation between white FST and dark-adapted b-wave amplitude and implicit time.
These data indicate that FST is sensitive for retinal functional changes due to proliferative diabetic retinopathy, and might add interesting information about visual function in clinical trials including these patients.
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