Demographic, medical and visual aspects of diabetic retinopathy and diabetic macular edema

M.Phil.Despite many years of research, diabetic retinopathy (DR), and diabetic macular edema (DME) remain difficult to diagnose, prevent, and treat. The complicated nature of the disease, the limited information on DR and DME and the increasing prevalence of diabetes mellitus (DM) in South Africa, provided motivation for this study. To the best of my knowledge, this is the first study in our country to identify demographic, medical and visual aspects of DR and DME collectively. A further incentive was the availability in optometry of recently developed computer software based upon multivariate statistics, which provided a unique opportunity to analyze, for example, tri-variate contrast sensitivity acuities using stereo-pair scatter plots. All refractive status measurements were also analyzed and compared with the same method. Together, the results from this study provide a broader clinical and research perceptive on DR and DME. In this cross-sectional study, 202 diabetic patients at the Helen Joseph Hospital in Johannesburg were recruited. Demographic variables included age, gender, race, age of diagnosis, duration of DM, and social habits. Medical variables included systemic conditions present, blood pressures, body mass index (BMI), lipid profiles, glycerated haemoglobin (HbA1c), and other available biochemical data (for example cholestrol, urea and creatinine levels). Visual variables included, distance, pinhole and near visual acuities, contrast sensitivity acuities, refractive status measured with autorefraction, colour vision, Amsler grid, intra ocular pressures (IOP), and fundus photography. Administration of the Impact of Visual Impairment (IVI) questionnaire provided new information concerning the restrictions in daily living participation caused by DR or DME. The predominant characteristics of the study population consisted of Type 1 DM among female Coloured subjects. Approximately 66% of all subjects had also been diagnosed with hypertension. The mean age of the subjects was 52 (± 14) years, age of diagnosis 41 (± 13) years, and duration of DM 10.8 (± 9.7) years. Mean blood pressures (136/81 ± 20.5/11 mmHg) and glycerated haemoglobin (HbA1c, 9.9 ± 3.4%) values were slightly higher than the recommended control levels (BP= 120/80 mmHg and HbA1c = 6 to 7%). However, mean total cholesterol and all other biochemical tests results were within recommended control ranges. Visually, mean refractive states were near emmetropia. Both distance visual acuities and pinhole acuities displayed mild visual loss, between 6/9 and 6/12. Mean contrast sensitivity acuities decreased from 6/12 to 6/24 to 6/60, as contrast levels were reduced from 100% to 10% and 2.5% respectively. A high percentage (75%) of tritan colour defect was found overall. Mean intra ocular pressures in the right and left eyes were approximately 17 (± 4.8) mmHg, and 21% of subjects demonstrated Amsler grid defects. Subjects reported an average of 21.8 (± 27) months since their last eye examination. Higher mean scores in the emotional and mobility domains of the IVI questionnaire were noted. Overall prevalence of diabetic retinopathy (DR) was 22.8% and diabetic macular edema (DME) 12.5%