Blue flash ERG PhNR changes associated with poor long-term glycemic control in adolescents with type 1 diabetes.
OBJECTIVE
To investigate the relationship between long-term glycemic control and photopic negative response (PhNR) changes in the blue flash ERG in adolescents with type 1 diabetes (T1D) without diabetic retinopathy (DR).


METHODS
After light adaptation, ERG responses to 1.60 cd·s/m(2) blue (420 nm) flashes (blue flash ERG) and 3.0 cd·s/m(2) white flashes (LA 3.0 ERG) were recorded in 22 patients (age range, 12 to 19 years) and 28 age-similar control subjects. The primary outcome measure was the amplitude of the PhNR. Secondary outcome measures were the amplitude and implicit time of the a-wave and b-wave. Multiple regression analyses were conducted with glycated hemoglobin (HbA(1c)) values and the time since diagnosis of T1D as covariates.


RESULTS
Blue flash ERG PhNR amplitudes were reduced (P = 0.005) in patients compared with control subjects. Multiple regression analysis demonstrated that a 1-unit increase in HbA(1c) was associated with a 15% decrease in the blue flash ERG PhNR amplitude (r = 0.61, P = 0.003). Compared with controls blue flash ERG a-waves (P = 0.03) and b-waves (P = 0.02) were delayed in patients but were not significantly associated with HbA(1c) or time since diagnosis of T1D. None of the ERG measures in the LA 3.0 ERG were significantly different in patients compared with controls.


CONCLUSIONS
Poorer long-term glycemic control is associated with worsening inner retinal dysfunction involving short-wavelength cone pathways of adolescents with T1D and no clinically visible DR. Future studies are warranted to determine whether changes in the blue flash ERG PhNR are a predictive marker of subclinical DR.
Ophthalmology and Vision Sciences and, The Hospital for Sick Children, Toronto, Ontario, Canada.
Michelle
M
McFarlane
Tom
T
Wright
Derek
D
Stephens
Josefin
J
Nilsson
Carol A
CA
Westall
D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000502:physiology*; D016022:Case-Control Studies; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology; D004596:Electroretinography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D012160:Retina / Q000503:physiopathology*; D017949:Retinal Cone Photoreceptor Cells; D012307:Risk Factors; D055815:Young Adult
D001786:Blood Glucose