June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
The effects of diabetic retinopathy and pan-retinal photocoagulation on photoreceptor cell function as assessed by dark adaptometry
Author Affiliations & Notes
  • Clay Bavinger
    Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
  • Grace Boynton
    Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
  • Maxwell Stem
    Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
  • Gregory R Jackson
    MacuLogix, Hummesltown, PA
  • Thomas Gardner
    Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
  • Footnotes
    Commercial Relationships Clay Bavinger, None; Grace Boynton, None; Maxwell Stem, None; Gregory Jackson, Maculogix (E), Maculogix (I), Maculogix (P); Thomas Gardner, Johnson and Johnson (C), Kalvista (C), NovoNordisk (C)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 4681. doi:
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      Clay Bavinger, Grace Boynton, Maxwell Stem, Gregory R Jackson, Thomas Gardner; The effects of diabetic retinopathy and pan-retinal photocoagulation on photoreceptor cell function as assessed by dark adaptometry. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4681.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

The effects of diabetic retinopathy and pan-retinal photocoagulation (PRP) on retinal cell function have not been fully described. We hypothesized that rod and cone cell dysfunction would increase with severity of diabetic retinopathy, and that PRP would exacerbate this dysfunction.

 
Methods
 

Dark adaption responses were obtained in an observational study from subjects with diabetes mellitus (N = 121, mean age: 45) and healthy controls (N = 23, mean age: 49), using the AdaptDx dark adaptometer (MacuLogix, Inc) which measures the sensitivity of cone photoreceptors and recovery speed of rod photoreceptors after bleaching with a 2-millisecond 5.8x10^4 scotopic cd/m2 sec flash. Inclusion criteria were (1) diabetes mellitus (unless a control); (2) age ≥ 18 years; (3) best corrected visual acuity ≥ 20/400. Software was developed to describe several parameters of the response, including cone sensitivity, rod recovery speed, and time until seeing a stimulus intensity of 5 x 10^-3 cd/m2 (the rod intercept time). Mann-Whitney U tests were used to compare variables between groups, with significance defined as a p-value < 0.05. This study was conducted at the W. K. Kellogg Eye Center after approval by the University of Michigan Institutional Review Board.

 
Results
 

Two main outcomes showed significant differences between controls (N = 23) and diabetic subjects with proliferative diabetic retinopathy (PDR) (N = 15), including cone sensitivity (controls mean: 2.1 log units; PDR mean: 1.8 log units; p = 0.0003) and rod recovery speed (controls mean: 0.29 log units/min; PDR mean: 0.21 log units/min; p = 0.02). None of the outcomes were significantly different between subjects with PDR (pre-PRP) and those with PRP. Multivariable regression model of subjects who had undergone PRP (N = 40) found no significant effects due to time since PRP, but did find significant effects due to age for rod recovery speed (p < .001) and rod intercept time (p = 0.001).

 
Conclusions
 

The results suggest that photoreceptor cell dysfunction, as assessed by dark adaptometry, begins at the PDR stage, and rod and cone cells are affected to similar degrees. Surprisingly, PRP did not further impair dark adaptation. The findings reveal multiple defects in retinoid function and provide potential points to improve visual function in persons with PDR.  

 
Normal dark adaptation response with study paramaters listed
 
Normal dark adaptation response with study paramaters listed

 
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