HbA1c and retinal sensitivity in diabetics using microperimetry.

PURPOSE: The purpose of this study was to determine the relationship between HbA1c values and retinal sensitivity at central 10° using the MP-1 microperimeter. METHODS: A prospective study was carried out on 32 healthy subjects (control group) and 60 diabetic patients. The diabetic patients were divided into 2 groups. Group 1 comprised of 30 patients without diabetic retinopathy (DR) and group 2 had 30 patients with mild non-proliferative DR. A full-threshold microperimetry of the central 10° of retina (the macula) was performed on all subjects, utilizing 32 points with the MP-1. The relationship between light sensitivity and HbA1c value was calculated using linear regression analysis. RESULTS: Total mean sensitivity at 10° for group 1 without DR, group 2 with mild NPDR and control group were 18.67±0.83, 17.98±1.42 and 19.45±0.34 (dB), respectively. There was a significant difference in total mean retinal sensitivity at 10° between the 3 groups (F(2,89)=18.14, p=0.001). A simple linear regression was calculated to predict HbA1c based on retinal sensitivity. A significant regression equation was found (F(1,90)=107.61, p=0.0001, with an R2 of 0.545). The linear regression analysis revealed that there was a 0.64dB decline in mean retinal sensitivity within the central 10° diameter with an increase of 1mmHg of HbA1c. CONCLUSION: Retinal sensitivity at the central 10° of the macula is affected by changes in HbA1c values.

Macular retinal sensitivity using MP-1 in healthy Malaysian subjects of different ages.

PURPOSE: To determine the influence of age and gender on macular sensitivity to light in healthy subjects of 4 age groups using the MP-1 microperimeter. METHODS: A prospective study was carried out on 50 healthy subjects (age range: 18-60 years) divided into 4 age groups; 18-30 years, 31-40 years, 41-50 years and 51-60 years. Full-threshold microperimetry of the central 10° of retina was performed utilizing 32 points with the MP-1. Macula area was divided into four quadrants, which were superior nasal (SN), inferior nasal (IN), inferior temporal (IT) and superior temporal (ST). RESULTS: Total mean sensitivity at 10° for age groups 18-30 years, 31-40 years, 41-50 years and 51-60 years were 19.46 ± 0.30, 19.40 ± 0.39, 19.47 ± 0.35 and 18.73 ± 0.75 (dB), respectively. There was a significant difference in total mean retinal sensitivity at 10° and at the four quadrants with age but not for gender. The retinal sensitivity was highest in the IT quadrant and lowest in the SN quadrant for all age groups. The linear regression analysis revealed that there was a 0.019 dB, 0.016 dB, 0.022 dB, 0.029 dB and 0.029 dB per year age-related decline in mean macular sensitivity within the central 10° diameter in the SN, IN, IT and ST quadrants respectively. CONCLUSION: Among normal healthy subjects, there was a linear decline in retinal light sensitivity with increasing age with the highest reduction in the superior nasal quadrant and lowest in the inferior temporal quadrant.