April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Progressive Retinal Dysfunction in Adolescents with Type 1 Diabetes using Visual Electrophysiology Markers
Author Affiliations & Notes
  • Wylie Tan
    Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada
    Institute of Medical Science,
    University of Toronto, Toronto, Ontario, Canada
  • Tom Wright
    Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada
  • Carol A. Westall
    Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada
    Ophthalmology and Vision Sciences,
    University of Toronto, Toronto, Ontario, Canada
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 6080. doi:
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    • Get Citation

      Wylie Tan, Tom Wright, Carol A. Westall; Progressive Retinal Dysfunction in Adolescents with Type 1 Diabetes using Visual Electrophysiology Markers. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6080.

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

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Abstract

Purpose: : To examine retinal function over time in adolescents with Type 1 Diabetes (T1D) and no diabetic retinopathy (DR). Aims: 1) To identify functional changes over time using visual electrophysiology. 2) To determine if changes can be predicted by blood glucose control measured by hemoglobin (HbA1c) levels.

Methods: : Patients with T1D and no DR were assessed for localized retinal function using standard (mfERG) and slow-flash electroretinogram (sf-mfERG) on at least 2 occasions. The implicit time (IT) and amplitude of first order responses were measured. Data from 46 age similar controls provided the normal 95% confidence intervals for mfERG and sf-mfERG IT and amplitude response for each hexagon tested. Responses were converted to z-scores for IT and amplitude. Hexagons with z-scores ≥ 2 (IT) and those ≤ -2 (amplitude) were considered abnormal. HbA1c values, a measure of long-term glycemic control, were taken before and between test dates. Variance in HbA1c between visits was calculated for each patient (4±1 HbA1c values/patient). Linear regression analysis was conducted with change in number of abnormal hexagons between visits as the dependent variable and HbA1c at initial and last visits and variance between visits as covariates.

Results: : 11 patients (15±2 years old at first visit) underwent mfERG testing. Time between visits was 13.5±5.3 months. Time between first HbA1c levels and last testing date was 11.0±6.3 months. Mean variance in HbA1c between visits was 18.1±16.6. There was an increase in the number of abnormal hexagons for mfERG IT (4.3±7.5 hexagons; p=0.038), but not for amplitude. 10 patients (16±2 years old at first visit) underwent sf-mfERG testing. Regression modelling of sf-mfERG IT demonstrated that for every percent increase of HbA1c at first visit, there is an increase in 0.2 abnormal hexagons (p=0.016); in addition, for every unit increase in HbA1c variance, there is an increase of 0.07 abnormal hexagons (p=0.0086).

Conclusions: : The mfERG and sf-mfERG results demonstrate a progressive dysfunction of the retina in adolescents with diabetes. The combination of high initial HbA1c levels and large HbA1c variance can exacerbate the problem.

Keywords: diabetic retinopathy • electrophysiology: clinical • electroretinography: clinical 
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