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Naheed W Khan, Amro Omari, Katherine Joltikov, Jose Davila, Thomas W. Gardner; Analysis of Retinal Function in Patients with Proliferative Diabetic Retinopathy Treated with Panretinal Photocoagulation.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1890. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the effect of pan retinal photocoagulation (PRP) on retinal function in patients with proliferative diabetic retinopathy (PDR).
We performed an observational study to compare retinal function among patients who received PRP treatment for PDR in one eye and normal controls, at baseline (BL) before treatment and 12 months (12M) post treatment. Comparisons were made for the full field dark-adapted and light adapted electroretinograms (ERG), and the multifocal ERG (mfERG) amplitude ring averages for rings 1 to 6. Rod and cone photoresponse characteristics were analyzed using amplitude (Rm), and sensitivity (log S) by fitting the leading edge of the ERG a-wave to white flashes (maximum intensity 100 cd.s m-2), by a model of activation of phototransduction. Inner retinal function was assessed using the photopic negative response (PhNR) of the full field ERG elicited by 7 cd.s m-2 red flashes on a 20 cd.m-2 blue background.
6 eyes of 6 PDR patients, mean age 45.4 years (SD=11.6), and 16 eyes of 11 normal controls, mean age 43.0 years (SD=11.0) were evaluated. Patients were treated with a green laser with the number of burns ranging from 1052 to 3441. Statistically significant differences between control and PDR subjects at BL and 12M were noted for ERG rod and cone b-wave amplitudes and implicit times (P<0.0001 for all parameters), for mfERG amplitude ring averages (P<0.0001), and for PhNR amplitudes (P<0.0001). There was no significant difference between control and PDR subjects at BL or 12M for rod Rm or the cone Rm. However, there was a significant difference between control and PDR subjects at both BL and 12M for log S (P<0.0001 for both rods and cones). None of the measures showed significant changes between BL and 12 months. However, in 2 of 6 PDR subjects the 12M measures were reduced by 60% from BL values for all ERG parameters. These two patients had the least number of laser burns in the PDR group.
At 12 months post PRP treatment the ERG and mfERG are not reduced appreciably. Rod and cone Rm amplitudes showed minimal change but log S was significantly reduced relative to controls. While photocoagulation damages the peripheral rod rich retina, central retinal function measured by mfERG was affected in all patients. These data are important for understanding the mechanisms of vision impairment in persons with PDR.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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