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SIMES Introductory Speech by Assoc Prof Donald Tan

LAUNCH OF SINGAPORE MALAY EYE STUDY

Loss of vision and blindness is a major handicap in life, not only resulting in a significant reduction in the quality of life, but has also been proven to increase mortality rates in the elderly. However, to address this problem, we must first establish the major eye diseases causing low vision in Singaporeans, and the impact of visual loss in the community.

The Singapore Malay Eye Study (SiMES) is a research project designed to collect and document the frequency, causes and risk factors of blindness and visual impairment in our Malay community. SiMES is part of an overall strategy known as the Singapore Eye Disease Study (SEDS), which is conducted in several stages. We have previously conducted a study on Singaporean Chinese, and now SiMES aims to extend this to Singaporean Malays. In the future, we would like to evaluate eye diseases in Singaporean Indians.

SiMES will examine a total of 3,200 Malay adults aged 40-80 years. The participants are pre-selected through random sampling of designated residential districts in the Southern Central part of Singapore located in close proximity to the study clinic. SiMES is planned to run from August 2004 to December 2006.

Invitations will be sent to each selected individual. A trained team of recruiters will then follow-up with telephone calls and, if necessary, home visits to personally invite the participants for the study. The examination will include a detailed interview to assess medical history and lifestyle factors, a general examination (e.g., height, weight, and blood pressure), a clinical eye examination (e.g. vision, measurement of eye pressure) and eye photography.

SiMES will be the first large-scale study of its kind to be conducted for a Malay community sample in the world. SiMES will provide important and previously unavailable information on the frequency of the most important eye diseases affecting Malay Singaporeans, which will aid in prevention and treatment of these eye conditions.

SiMES is a Singapore Eye Research Institute (SERI) research program funded by a $500,000 grant from the National Medical Research Council (NMRC), and will be conducted in collaboration with participation from the Singapore National Eye Centre, National University Hospital, National University of Singapore and the Ministry of Health. SiMES is also strongly supported by both Yayasan Mendaki and the Islamic Religious Council of Singapore (MUIS), with both organisations actively advising and participating in this project.

DETAILS OF SiMES

1. Specific Aims

The study is a population-based, cross-sectional, epidemiological study aimed at determining the prevalence and risk factors of visual impairment, blindness and major eye conditions in adult Malays aged 40 to 79 years living in Singapore. Specific aims of the current study are to determine, in adult Malay people living in Singapore, the

1. Frequency and causes of bilateral and unilateral visual impairment and blindness
   
2. Frequency and risk factors of myopia (short sightedness) and other refractive errors, such as hyperopia (long sightedness), anisometropia (difference in refraction between right and left eyes) and astigmatism (irregular refraction)
   
3. Frequency and types (open, closed) of glaucoma, and their associations with myopia, eye and systemic risk factors.
   
4. Frequency and risk factors of age-related cataract and different types of cataract, and the overall utilization of cataract surgery
   
5. Frequency and risk factors of diabetic retinopathy, age-related macular degeneration and other retinal diseases
   
6. Association of retinal vascular signs to glaucoma, diabetic retinopathy and other conditions

2. Background

• The frequency and risk factors of visual impairment, blindness and cataract have been documented in China,^1-4 and India.^5-8
  
• In India, several studies have also reported on the epidemiology of myopia,⁹ glaucoma,^10,11 diabetic retinopathy,¹² and other diseases.¹³
  
• Relatively less data on these conditions in South East Asia are available. To address this, we initiated the Singapore Eye Disease Study (SEDS) programme, which is conducted in several stages in Chinese, Malays and Indians.
  
• The Tanjong Pagar Survey was conducted in Singapore in 1996-97. The Survey successfully examined and reported the prevalence and risk factors of glaucoma,¹⁴, myopia,^15-18 cataract,^19.20 and other diseases,²¹ among adult Chinese aged 40-79 years old. See below
  
• However, there is relatively little information on the epidemiology of low vision or major blinding eye diseases in people of Malay origin.^22,23 A small number of studies in Singapore have suggested that Malays may have a different spectrum of ocular diseases.
  
• Myopia in children and young adults,^24-26 acute angle closure glaucoma,²⁷ and retinal detachment,^28,29 appear to be less common in Malays compared to Chinese and Indians.
  
• In contrast, Malays appear to have higher rates of severe ocular trauma,³⁰ and possibly diabetic retinopathy.³¹ However, there is no large population-based study in Malays.
  
• SiMES therefore builds on the experience and knowledge obtained from the Tanjong Pagar Survey. SiMES will document the burden and risk factors of visual impairment and eye diseases in Malay people.
  
• The data will offer key insights into the etiology of the most common age-related eye diseases and also provide information for allocation of public health resources for nearly 300 million Malay people living in Asia alone.

3. Methods

SiMES will examine a total of 3,200 Malay adults aged 40-80 years. The participants are pre-selected through random sampling of designated residential districts in the Southern Central part of Singapore located in close proximity to the study clinic. SiMES is planned to run from August 2004 to December 2006.

Participants will receive the following examination:

• Interview
• Blood pressure, Height, Weight, Hip-Waist Circumference
• Ankle brachial index, vibration sense and fine touch
• Autorefraction and subjective refraction
• Visual Acuity (VA) Measurements
• Ocular Biometry (Measurement of eyeball size)
• Slit Lamp Examination of anterior part of the eye
• Intraocular pressure assessment
• Visual Field Examination
• Pupil Dilatation
• Cataract grading
• Retinal and Optic Disc Examination
• Lens Photography
• Retinal photography
• Blood collection

4. The Tanjong Pagar Survey

The main findings are:

• Bilateral low vision and bilateral blindness was found in 1.1% and 0.5% of the subjects. The rates of bilateral low vision and blindness increased with age. Cataract accounted for 60% of bilateral low vision and 20% of bilateral blindness. Glaucoma contributed to 60.0% of bilateral blindness.
  
• Glaucoma affects 3% of study population. Higher intraocular pressure (IOP) was an important determinant of glaucoma risk, and higher IOP was related to higher systolic blood pressures and increased corneal thickness.
  
• One in three participants had cataract. In those above 60 years, 8 of 10 people have age-related cataract. Diabetes, lower body mass index, cigarette smoking and lower socio-economic status were associated with cataract.
  
• Four of ten had myopia, and one in ten had high myopia.

5. Study Team

We have assembled an experienced and high-qualified team to undertake this project.

• Dr Wong Tien Yin, as PI, has a MD/PhD and dual training in ophthalmology and epidemiology. He has published more than 100 peer-reviewed papers in all aspects of ocular epidemiology and holds US NIH-funded grants for his current research. He was awarded the NUS 2004 Outstanding Researcher of the Year
  
• A/Prof Saw Seang Mei, the Co-PI, is an ophthalmic epidemiologist and the world’s leading authority in the epidemiology of myopia. She is the PI the Sumatra Eye Survey, and has more than 70 peer-reviewed papers. A/Prof Tan, the Co-PI, is the Director of SERI, and Deputy Director of SNEC. He holds numerous NMRC and BMRC grants.
  
• Dr Mohammed Rosman, Dr Loon Seng Chee and Dr Loo Jing Liang are young investigators who will lead the study in the clinic and home examinations.
  
• In addition, an eminent team of External Advisory Board member (Professors James Tielsch, Ronald Klein and Barbara Klein, Drs Paul Foster and Jie Jin Wang) will provide expertise and advice in this study. These members have conducted the ground-breaking Beaver Dam Eye Study, Baltimore Eye Study, and Blue Mountains Eye Study.

6. SUMMARY

SiMES will provide the following:

• Data on prevalence of visual impairment, blindness and major eye diseases in Malays will greatly assist planning of ophthalmic services for Singapore.
  
• Risk factor studies will provide insights into the etiology of eye diseases in Malays, which may lead to new therapeutic and preventive approaches to tackle these conditions
  
• Optimal methods of population screening for major eye diseases will be developed from knowledge obtained from this study
  
• Extrapolation of data to Malaysia, Indonesia and other countries with Malay-Muslim people

REFERENCES

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2. Li S, Xu J, He M, Wu K, Munoz SR, Ellwein LB. A survey of blindness and cataract surgery in Doumen County, China. Ophthalmology. 1999;106:1602-8.
3. He M, Xu J, Li S, Wu K, Munoz SR, Ellwein LB. Visual acuity and quality of life in patients with cataract in Doumen County, China. Ophthalmology 1999;106:1609-15.
4. Zhao J, Sui R, Jia L, Fletcher AE, Ellwein LB. Visual acuity and quality of life outcomes in patients with cataract in Shunyi County, China. Am J Ophthalmol. 1998;126:515-23.
5. Murthy GV, Gupta S, Ellwein LB, Munoz SR, Bachani D, Dada VK. A population-based eye survey of older adults in a rural district of Rajasthan: Central vision impairment, blindness, and cataract surgery. Ophthalmology. 2001;108:679-85.
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