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M. Laron, M. A. Bearse, Jr., K. Bronson-Castain, S. Jonasdottir, B. King-Hooper, S. Barez, M. E. Schneck, A. J. Adams; Multifocal Electroretinogram (mfERG) Implicit Time and Blood Glucose Control in Adolescents With Type 1 Diabetes. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4687.
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© ARVO (1962-2015); The Authors (2016-present)
The multifocal electroretinogram (mfERG) P1 implicit time (IT) has been shown to be delayed in diabetes, and to have predictive value for the development of local nonproliferative diabetic retinopathy (NPDR) in adults. This study, the first stage of a longitudinal study of adolescents with type 1 diabetes, evaluates relationships between mfERG parameters and disease variables including glycemic control.
MfERGs, HbA1c and blood glucose (BG) concentration were obtained from 37 type 1 diabetic adolescents with no retinopathy (aged 13 to 20 years; best corrected VA 20/20 or better), and 30 age-matched control subjects. For the patient group, additional HbA1c values over a period of one year were obtained. P1 IT and amplitudes were measured for first order mfERG responses from 103 regions within the central 45 degrees of the right eye of each subject using a template scaling technique1. Group differences in mfERG IT and amplitudes between patients and controls were tested across the field, and at eccentricities of 0-5 deg, 5-10, 10-15, and 15-22 deg. Linear regression analyses were used to evaluate associations of mfERG amplitudes and IT with HbA1c, and BG. T-tests were performed to assess differences between patients and controls.
Mean mfERG IT across the 45 degrees field was not different between patients and controls (p=0.42). However, mfERG IT by location differed between patients and controls (p<0.001, paired t-test). This difference was significant from 5 to 22 degrees eccentricity (p<0.001). Higher HbA1c values measured on the day of mfERG recording were correlated with longer mfERG IT (R2=0.14, p=0.02). mfERG IT was not associated with the duration of diabetes, mean HbA1c over one year, or BG concentration at the time of recording. No association was found between mfERG amplitudes and blood glucose control including all BG measures.
The correlation between HbA1c and mfERG IT suggests that better blood glucose control may help to reduce the risk for local retinal neuropathy, and is similar to our findings in a previous pilot study2. In the future, it will be important to learn whether there is an association between adolescent blood glucose control and mfERG implicit times longitudinally. We are following patients to determine whether such an association exists.1. Hood and Li, 1997 2. Bronson-Castain et al. ARVO 2008.
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