Epidemiology of diabetic retinopathy in Oman: Two decades of research

In 2013, 382 million people had diabetes worldwide. This number is expected to increase to 592 million by 2035.[1] In Oman, the prevalence of diabetes mellitus (DM) was reported to be 12.3% in the population aged 18 years and above.[2] Applying this figure to the adult population on Oman would indicate that there were 112,000 diabetics at the beginning of 2014.[3] The increase in the prevalence of DM and the increase in life expectancy of people with diabetes will result in a significant increase in visual disability due to the ocular complications of diabetes. Currently, the National Diabetes Register in Oman has 80,000 patients with diabetes.[2] Based on World Health Organization (WHO) recommendations, these individuals will require a yearly assessment or screening for diabetic retinopathy (DR).[4] Given that the range of DR prevalence reported for Oman is between (14.5% and 42.2%, there are between 16,000 and 47,000 cases of DR throughout the country.[5,6] Of these, nearly 10% (1,600–4,700 cases) have sight-threatening diabetic retinopathy (STDR) requiring laser and/or intravitreal injections of anti-angiogenic factors for treating proliferative diabetic retinopathy and diabetic macular edema.[7] Annual screenings for DR for all individuals with DM would likely come at the expense of compromising other eye care services or at result in lower quality at point of ophthalmic care. To ease the burden of work, some have recommended training allied eye care professionals to perform retinal photography, grading, and assessment through telemedicine after linking regional referral hospital with a major Tertiary Ophthalmic Care Hospital.[8]

All individuals identified by a screening program should be managed for their medical conditions.[9] This effort will require enhancing the resources and capabilities of managing DR at the governorate levels. As there is a well-established primary health care system and diabetes control program in Oman, some primary prevention measures for DR and DM have been implemented through them like promotion for adopting healthy lifestyle, provision of medications for diabetes at village level at no cost, providing resources to monitor glycemic levels at PHCs/diabetes centers.[10] The Eye Health Care Program unit at the Ministry of Health must have experienced personnel to effectively monitor and further enhance these initiatives.[11] Some selected governorate hospitals currently motivate and manage STDR defaulters.[12] This experience must be reviewed, and positive aspects of it be generalized to other regional hospitals. Periodic and supervised trainings of general ophthalmologists of the governorate hospitals in DR screening and management are recommended to improve the systems and gain patients confidence.

Patients default rates especially for annual screening among diabetics with more than 5-year duration are high in Oman and thus improving patient compliance for DR screening, with laser treatment and follow-up management is paramount to the any objectives to reduce the burden of diabetic eye complications. This involves appropriate counseling by the diabetes care providers in primary care and timely referral as warranted.[13]

In most cases, despite all efforts, advanced STDR cases will, unfortunately, progress to being visually handicapped. This leads to a significant decrease in vision-related quality-of-life especially for patients with severe and bilateral STDR.[14] Laser treatment for STDR was partially responsible for compromised visual functions. However, it has limited effects on visual quality-of-life.[15] Low vision care can rehabilitate many of these diabetic cases.

Patient groups play a major role in decision-making and supporting each other and should be promoted. In addition, patient support groups can work as a team with service providers to provide feedback about client perspective, generating resources, increasing awareness about prevention of eye complications among diabetics and promoting healthy lifestyle. Most importantly, diabetic patient groups could focus on improving the uptake of screening and management of patients with DR.[16]

A recent review report of the Eye Health Care Program had supported the Primary Health Care approach, screening initiatives at Secondary Eye Care Units, comprehensive approach to address underlying causes of diabetes and its complications and establish linkages with different stakeholders dealing with diabetes. However, program review experts urged the government to strengthen the management of DR and organize low vision services to visually impaired diabetics.[17] WHO has recommended setting up indicators and monitoring them for DR.[18] The Eye Health Care Program is invited to adopt and apply these indicators in the Sultanate to achieve the goals of “VISION 2020.”