ORIGINAL ARTICLES

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PREVALENCE OF DIABETIC RETINOPATHY IN A PRIMARY CARE SETTING USING DIGITAL RETINAL IMAGING TECHNOLOGY

Keah Say Hien FRACGP, Elizabeth Medical Centre, Muar, Johor.
Chng Kooi Seng FRACGP AM, Klinik Chng, Johor Bahru, Johor.

See also Commentary by Sagili Chandrasekhara Reddy and “Test Your Knowledge”.

INTRODUCTION
Diabetic retinopathy is the commonest complication of diabetes mellitus and is the earliest manifestation of the microvascular complications of diabetes mellitus. In the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR), a large population based study in 10 counties in southern Wisconsin, USA, the prevalence of any retinopathy in those with onset of diabetes after the age of 30 years (presumably mostly with Type 2 DM) is 29% in those within 5 years of diagnosis and 78% in those with disease duration more than 15 years.² Diabetic retinopathy is the commonest cause of blindness in the working age population in the developed countries. Diabetic retinopathy fulfils all the criteria for a screening program. It occurs as a continuum, where in the early subclinical stages, changes in the retina can only be demonstrated by the use of fluorescein angiography, to the stages whereby ophthalmologic examination reveals retinopathy but the visual acuity is still unaffected, to the final stages whereby severe visual impairment and blindness occur.

In the local context, well organised screening programmes for diabetic retinopathy is still lacking in the private practice or the government hospitals. We were of the impression that screening for diabetic retinopathy in primary care locally by routine funduscopy is infrequently done and that some general practitioners may find the procedure difficult due to personal and environmental factors.

The objective of our study was to determine the prevalence of diabetic retinopathy in a primary care clinic and the associated demographic factors by using digital retinal imaging technology as the sole screening instrument.

MATERIALS AND METHODS
The study was conducted in a primary care clinic in Muar, Johor. This clinic provides private healthcare services to the residents in this town as well as the surrounding rural community. It is located about 2 km from Muar Hospital (Hospital Pakar Sultanah Fatimah, Muar).

This study is a cross-sectional study of all patients with type 2 diabetes mellitus 18 years and above who attended the clinic from 24th March 2005 to 24th August 2005. The diagnosis of diabetes mellitus was based on the currently accepted criteria. We included all diabetic patients seen during the study period if they gave consent but excluded those who were acutely ill or non-ambulant.

Diabetic patients answered a brief questionnaire asking for demographic details and information about their diabetes (age of onset, duration of diabetes, co-morbidities, whether the subject had ever been under the care of an ophthalmologist). Visual acuity was tested using Snellen chart at 6 metres. Distant vision was tested with and without spectacles (retested with pinhole if the subject was unable to read the 6/9 line). A general examination of the eye was done using the penlight to look for clarity of the cornea and to assess the pupil size. Ophthalmoscopic examination was performed in a darkened room to look for cataract but the fundus was not examined. Retinal photography was then performed using the Topcon TRC NW200 nonmydriatic retina camera. A single central macular view of the fundus (including the optic disc, the vascular arcades and the macula) was obtained and was used in this study for assessment of diabetic retinopathy. If the image was deemed inadequate 2 drops of a cycloplegic (Mydriacyl) was instilled into the eye and the eye was reexamined when the pupillary dilatation was adequate. The images acquired by the camera were instantly transmitted to a computer for storage and subsequent retrieval and analysis.

The fundus photographs were carefully analysed by both authors. The retinal abnormalities were classified according to the International Clinical Diabetic Retinopathy Disease Severity Scale (Table 1) and the International Clinical Diabetic Macular Edema Disease Severity Scale (Table 2) produced by the International Council of Opthalmology.³

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