Changing trends of population and blindness in Oman: A need for urgent action.

The Omani population increased from 1.5 million in 1993 to 2.6 million in 2010. It is forecasted to be 8.31 million in 2050. Improved health has resulted in more people in the “40 plus” age group. It is expected that people aged 65 and more will increase from 3% in 2010 to 10.5% in 2050.[1] The Omani population above 40 years by gender in the three censuses in 1993, 2003, and 2010 are depicted in Figure 1. For health planning, one should note this changing population and projections.

Figure 1

Omani population ≥40 years in 1993, 2003, and 2010 and the projected population in 2050. In the population pyramid, red is female and blue is male

Non-communicable eye diseases such as diabetic retinopathy, glaucoma, cataract, and their resulting visual disabilities are more prevalent in the 40 years and above population.[2] According to the recent global estimates, the people of 50 years and older age group constituted 82% of total blind worldwide.[3] Thus, early detection of visual impairment in population aged 40 and more would be crucial if avoidable blindness is to be eliminated by the year 2020.

Three community-based prevalence studies were conducted in Oman in 1996, 2005, and 2010. They were based on the census data of 1993, 2003, and 2009 and the blindness rates at national level were calculated accordingly.[45] In all three surveys, blindness was defined as best-corrected visual acuity of less than 3/60 and corresponding restriction of field of vision. Trained mid-level eye care staff carried out initial visual acuity testing and ophthalmologist performed further assessments and labeling the cause of visual disability per eye and per person. In each survey, the sample was calculated for finding the prevalence rate at national level. The rates for gender and age groups therefore suggested trends only. The blindness rate and the projected number of persons with blindness increased by time. The blind persons among 40 years and older populations were projected to be 19,500, 22,500, and 28,500 in the year 1996, 2005, and 2009, respectively. Recent global estimates also suggest that visual disabilities are increasing.[3] If latest blindness rate is applied to the population of 2050, there could be 165,000 blind in same age group in Oman.

The changes in the population in last three decades could affect the blindness estimation. Calculating prevalence using direct standardization will help in addressing the effect of changing population in three surveys [Table 1]. This exercise revealed that there was significant decline in blindness rate from 1996 to 2005. But the magnitude of blindness in 2009 survey was similar to that found in 1996. Initial commitment and ability to address avoidable blindness due to trachoma, cataract could be responsible for the decline of blindness rates between first two surveys. The cataract surgery rates (CSR) in last 5 years has remained around 2,000/million/year.[6] The increasing number of people with glaucoma and sight-threatening diabetic retinopathy on the other hand could be the reason for the increase in the blindness rate during the period between last two surveys.

Table 1

Direct standardized prevalence rates of blindness (best.corrected visual acuity of <3/60) in three surveys (index is 2009 population)

The increase of prevalence of blindness was significantly higher among females as is noted in other studies.[7] This observation should be further investigated and gender barrier for specific blinding eye condition must be tackled urgently.

The age group “60 to 69 years” had significant increase in blindness rates between 2005 and 2009. Including vision screening within screening initiative for non-communicable diseases in Oman is recommended for early detection and prompt management of diseases causing visual disabilities in elderly population.[8]

A revision of ICD10 code to define visual impairment and blindness has been proposed to include magnitude of visual disabilities due to uncorrected refractive error. If this definition is applied in Oman, the prevalence of blindness will be much higher.

The review of causes of blindness suggested that communicable and nutritional eye diseases cause lesser visual disabilities now compared to the past. Blinding trachoma seems to be no more a public health problem in Oman.[9] The prevalence of diabetes among more than 20 years old Omani population was 12.2% in 2009.[10] Hence, severe visual disabilities due to eye complications of diabetes are likely to increase in coming years.

A large proportion of eyes operated for cataract had vision less than 3/60 before surgery. With improved visual need of educated people in coming years in Oman, the criteria for cataract surgery could become 6/60 instead of 3/60. In this case, Oman will face huge backlog of unoperated cataract resulting in visual disabilities in coming years. The facilities should be improved in all regions of Oman to increase CSR especially in females.

In spite of effective intervention, a large number of visually disabled persons will need rehabilitation to improve their quality of life. A consorted effort of all stakeholders is urgently needed to upgrade the existing vision rehabilitative services both for blind and low vision disabled in Oman.

In conclusion, the increasing proportion of elderly population will cause increased burden of blinding eye diseases especially due to chronic age-related eye diseases in Oman. Despite accounting for changing population, the blindness rate seems to increase especially among elderly females. Proactive efforts in first half of VISION 2020 Oman seem to have less impact in later half of this decade in addressing chronic and unavoidable causes of blindness. Increasing the CSR and public health approach to address diabetic retinopathy and glaucoma are recommended. Future health planning in Oman should include provision of vision rehabilitation services to the aged population.