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K. Bronson-Castain, M. A. Bearse, Jr., J. Neuville, S. Jonasdottir, B. King-Hooper, M. E. Schneck, A. J. Adams; Functional and Structural Changes in the Adolescent Diabetic Retina. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5996.
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© ARVO (1962-2015); The Authors (2016-present)
It has been shown that the multifocal electroretinogram (mfERG) and optical coherence tomography (OCT) are useful measures in detecting functional and structural changes in adults with diabetes. The goals of this study are to examine retinal function based on mfERG, retinal thickness measured by OCT and the relationship between the two measures in both type 1 and type 2 diabetic adolescents.
mfERG and OCT measurements were made on 30 adolescents with type 1 diabetes (6.5 ± 4.0 yrs duration), 9 adolescents with type 2 diabetes (2.2 ± 1.2 yrs) and 22 age-matched controls. First order mfERGs were derived from 19 hexagons within the central ~15 degrees of the retina (Veris Science 4). First order implicit time (IT) and amplitudes (AMP) were measured using a template stretching method (Hood & Li, 1997). 12 radial retinal thickness slices were measured within the central 20 degrees of the retina (Zeiss Stratus OCT 3). Slices were then imported into Matlab and points between each scan were interpolated creating a map of the central 20 degrees. Thickness measurements were assigned to the corresponding 19 hexagons of the mfERG stimulus and a mean thickness was generated for each hexagon.
The diabetic group IT (28.0 ± 0.1ms) was more delayed (p < 0.001) than the control group (27.7 ± 0.1ms). The diabetic group AMP (0.24 ± 0.01µV) did not differ (p = 0.19) from the control group (0.24 ± 0.01µV). Retinal thickness did not differ (p = 0.28) between the diabetic group (266 ± 2µm) and the control group (268 ± 2µm). However, local thickness had a weak positive correlation with IT (R2 = 0.07, p<0.001) and AMP (R2 = 0.04, p<0.001). Type 1 (27.9 ± 0.1ms) and type 2 (28.1 ± 0.1ms) were delayed in IT from the control (p < 0.001). The type 2 group IT was also more delayed than that of the type 1 group (p < 0.001). The type 2 group (0.22 ± 0.02µV) had smaller AMP (p < 0.001) than both the control and type 1 (0.24 ± 0.01µV) groups.
mfERG implicit time is significantly delayed in adolescents with diabetes. This is similar to that observed in adult diabetics. Only in the type 2 group does amplitude also appear to be affected. Although the retinal thickness of the diabetic group was not abnormal, the data suggest that local retinal function is related to local retinal structure in adolescents with diabetes. Despite the short duration of diabetes and lack of retinopathy in this sample, the results show retinal function is affected early in adolescent diabetes.
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