Screening for diabetic retinopathy using a non-mydriatic retinal camera in rural Victoria

PURPOSE: To develop a screening programme for the early detection of diabetic retinopathy using non-mydriatic retinal photography. METHODS: A community based screening service was offered to all people with known diabetes mellitus in selected townships in the LaTrobe and Goulburn Valleys in Victoria. At the local examination centre, basic sociodemographic information was collected as well as details of previous use of eye care services for the early detection of diabetic retinopathy. The examination included visual acuity (VA), glycosylated haemoglobin level and Polaroid photographs of each fundus using a Canon CR5-45NM non-mydriatic retinal camera (Canon, Tochigiken, Japan). Dilating drops were not used. Photographs were subsequently reviewed and letters were sent to all participants (with copies to their general practitioners) with recommendations for appropriate follow up. RESULTS: A total of 1177 people with diabetes attended the screening service, which is estimated to be 40% of the total population with known diabetes in the study area. The mean age was 65 years (range 20-94 years); 559 (48%) people reported not having a dilated fundus examination within the past 2 years; 345 (29%) people had never had a dilated fundus examination. Of the 2354 eyes, 2126 (90%) of the photographs were gradable. A total of 704 people (60%) had normal VA and no evidence of diabetic retinopathy, 209 people (18%) had diabetic retinopathy, 101 people (9%) had evidence of other fundus pathology, 42 people (3%) had reduced acuity (< 6/18) in one or both eyes (with no fundus pathology evident) and 121 people (10%) had ungradable photographs in one or both eyes. CONCLUSIONS: The present study demonstrates the usefulness of a screening programme with non-mydriatic retinal photography as an adjunct to current eye care services for the early detection of diabetic retinopathy.

Use of eye care services by people with diabetes: the Melbourne Visual Impairment Project

AIM: The use of eye care services by people with and without diabetes was investigated in the Melbourne Visual Impairment Project (VIP), a population based study of eye disease in a representative sample of Melbourne residents 40 years of age and older. METHODS: A comprehensive interview was employed to elicit information on history of diabetes, medication use, most recent visit to an ophthalmologist and optometrist, and basic demographic details. Presence and extent of diabetic retinopathy was determined by dilated fundus examination. RESULTS: The Melbourne VIP comprised 3271 people who ranged in age from 40 to 98 years; 46.2% of them were male. Of 3189 people who had the fundus examination and knew their diabetes status, 162 (5.1%) reported having been previously diagnosed with diabetes and, of these, 37 (22.2%) were found to have diabetic retinopathy. Seven people (4.3%) had developed diabetes before age 30. The mean duration of diabetes was 9.2 years. People with diabetes were significantly more likely to have visited an ophthalmologist ever or in the past 2 years than people without diabetes. However, 31.8% of people with diabetes had never visited an ophthalmologist. The proportion of people who had never seen an ophthalmologist was 47.1% for people without diabetes, 34.2% for people with diabetes but without diabetic retinopathy, and 25% for people with diabetic retinopathy. Sixty one per cent of people with diabetic retinopathy had seen an ophthalmologist in the past year and a further 3% within the past 2 years. People with diabetes were not significantly more likely to have visited an optometrist than people without diabetes (p = 0.51). Overall, 37.7% of people with diabetes and 32.9% of people without diabetes had visited an optometrist within the past year (chi 2 = 2.25, 1 df, p = 0.13). Information concerning retinal examinations was available for 135 individuals (83.3% of people with diabetes). Only 74 (54.8%) could recall ever having a dilated fundus examination; 10 (14%) by an optometrist, 62 (86%) by an ophthalmologist, and five (7%) by a general practitioner. Of those 68 people who had seen an ophthalmologist in the past 2 years, 48 (71%) reported a dilated fundus examination during that time. This compares with 28 (43%) reported dilated fundus examinations in the 65 people who had seen an optometrist in the past 2 years. This finding is statistically significant (chi 2 = 10.2, 1 df, p < 0.005). CONCLUSION: These results indicate that nearly half of people with diabetes in Melbourne are not receiving adequate screening or follow up for diabetic retinopathy, despite universal health care.

Examination compliance and screening for diabetic retinopathy: a 2-year follow-up study

Early detection and timely treatment of diabetic retinopathy can preserve vision, yet many people with diabetes do not have their eyes examined regularly. The purpose of this study was to examine eye care practices of people with diabetes who had not previously accessed eye care services on a regular basis. Screening with non-mydriatic retinal photography for diabetic retinopathy was initiated in 1996, and targeted people with diabetes who did not access eye care services on a regular basis. Each test area was revisited 2 years after the initial screening. Patients that did not attend the biennial screening were followed up by mail survey. Although none of the participants in this study had been previously accessing eye care services on a regular basis, 87% did so after attending the screening. These results indicate that mobile screening with non-mydriatic photography, as an adjunct to current eye care services, has the potential to increase examination compliance for diabetic retinopathy and to achieve sustained behaviour change.

Retinal thickness profile of individuals with diabetes

PURPOSE: To examine the retinal thickness profiles of individuals with and without diabetic retinopathy (DR).

METHODS: Full retinal thickness in the central zone, overall and hemisphere thicknesses of the parafovea and perifovea, ganglion cell complex (GCC) thickness and retinal nerve fibre layer (RNFL) thickness were assessed in 185 individuals using spectral domain optical coherence tomography (88 individuals with diabetes but no DR, 55 with DR, and 42 non-diabetic controls). The DR group comprised of 60% of participants with very mild non-proliferative diabetic retinopathy (NPDR) (representing microaneurysms only) and 40% with mild NPDR (hard exudates, cotton-wool spots, and/or mild retinal haemorrhages). Regression analysis was performed to determine the factors associated with retinal tissue thickness, taking into account, age, sex, presence of DR, duration of diabetes, HbA1c levels and type of diabetes.

RESULTS: The mean (S.D.) of the overall parafoveal thickness was 306 (16) in the DR group and 314 (14) in the control group (p = 0.02). The mean (S.D.) of the superior hemisphere parafoveal thickness was 309 (16) in the DR group and 318 (14) in the control group (p = 0.02). The mean (S.D.) of the inferior hemisphere parafoveal thickness was 303 (17) in the DR group and 311 (15) in the control group (p = 0.02). There were no significant differences in retinal thickness between groups in the central zone (p = 0.27) or perifovea (p > 0.41). Neither the overall nor the hemisphere RNFL (p > 0.75) and GCC thickness (p > 0.37) were significantly different between the groups. Regression analysis revealed that parafoveal thickness in diabetic individuals was reduced in association with presence of DR (B = -5.9 μm, p = 0.02) and with advancing age (B = -4.5 μm, p = 0.004, for every 10 year increase in age) when adjusted for sex, duration of diabetes, HbA1c levels and type of diabetes.

CONCLUSION: The inner macula is thinner in the presence of clinical signs of diabetic retinopathy and is compounded by advancing age. The influence of any macular oedema or that by cotton-wool spots could not be ruled out and may still confound these results.