Prevalence and causes of blindness and diabetic retinopathy in Southern Saudi Arabia

Objectives:

To determine the prevalence and causes of blindness and diabetic retinopathy (DR) in Jazan district, Southern Saudi Arabia.

Methods:

Using the standardized Rapid Assessment for Avoidable Blindness (RAAB) and DR cross-sectional methodology, 3800 subjects were randomly selected from the population of ≥50 years of age in Jazan, Saudi Arabia between November 2011 and January 2012. Participants underwent screening comprised of interview, random blood glucose test, and ophthalmic assessment including visual acuity (VA) and fundus examination. Among participants with VA <6/18 in either eye, the cause(s) of visual impairment was determined. Participants were classified as diabetic if they had previous diagnoses of diabetes, or random blood glucose >200 mg/dl. Diabetic participants were assessed for DR using dilated fundus examination. All data were recorded using the RAAB + DR standardized forms.

Results:

The prevalence of bilateral blindness <3/60 was 3.3% (95% confidence interval [CI]: 2.74 - 3.90). Cataract was the leading cause of blindness (58.6%); followed by posterior segment diseases (20%), which included DR (7; 3.3%). The prevalence of diabetes mellitus (DM) was 22.4%, (95% CI: 21.09 - 23.79), among them; 27.8% had DR. The prevalence of sight-threatening DR was 5.7%.

Conclusion:

The prevalence of DM and the corresponding proportion of DR in this region is lower than that reported in other regions of Saudi Arabia. However, the prevalence of blindness not related to DR is relatively higher than the other studies.The Kingdom of Saudi (KSA) ranks seventh in the global burden of diabetes mellitus (DM), with an estimated prevalence of 23.5% for age groups 20-79 years.1 Ocular complications are quite common among diabetic patients. It is well established that within 15 years of diabetes approximately 2% of diabetics may turn legally blind, and approximately 10% may develop severe visual impairment. Diabetic retinopathy (DR) is one of the serious potential complications. It occurs in approximately 77% of the type 2 diabetics within 10 years of the diabetes onset, and almost in all type 1 diabetics.2 A global review of diabetic retinopathy reported that on average, 34.6% of all diabetic patients have some forms of DR.3 Recent studies in KSA have reported a high prevalence of DR among diabetics in different regions of the country. A recent population based study in Taif,4 in the Western region of KSA reported that 33% of all diabetics have some form of DR; while another hospital based study in the Madinah region reported the same estimate at 36%.5 With this high burden of the disease, the Saudi Ministry of Health (MoH) in collaboration with the Saudi National Prevention of Blindness Committee (NPBC) commissioned more studies to determine the magnitude of the problem in other regions of the vast country. Thus, a population-based survey was conducted to estimate both prevalence and pattern of DR, in addition to the magnitude and causes of blindness and visual impairment in the Jazan district, in the Southwestern region of KSA. Jazan covers an area of 11,670 Km², and has a population of 1,533,496 inhabitants. It lies to the Southwest coast of the Red Sea and is bordered by Yemen to the south. The study adopted the Rapid Assessment for Avoidable Blindness and Diabetic Retinopathy (RAAB+DR) technique, which is a survey methodology developed by the International Centre for Eye Health, London School of Hygiene and Tropical Medicine (ICEH-LSHTM), London, United Kingdom.6 The RAAB+DR is a simple and cost effective cross-sectional community-based survey of persons 50 years and older, that focuses primarily on the prevalence of avoidable blindness. It estimates the prevalence of blindness and visual impairment, their causes, and magnitude of DR in a specific geographical area, usually at the district, or province level. The RAAB+DR methodology has concrete proven reliability and validity.4,7