Reading Material for the Prevention of Blindness Workshop



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Introduction

Cambodia has an estimated population of 12 million people, 85% of whom live in rural areas. With a blindness prevalence rate of 1.2%, an estimated 144,000 people are blind. The main causes of blindness are cataract, uncorrected refractive errors / aphakia, glaucoma, corneal scar and pterygium. Of these causes, 80 – 90% are preventable or treatable. There is shortage and maldistribution of health manpower; infrastructures and facilities to tackle the identified eye care problem. The lack of training programmes in the country also compounds this problem.
An estimated 28,800 Cambodians become blind each year, about 19,000 because of cataract alone. Cataract surgical services are available in most of the eye units in the country. However, by 2020, the country’s population is projected to grow from 12 million to 19.5 million people. By the same year, with increasing life expect ancy, the number of Cambodians over the age of 60 is estimated to increase by 60% to some 2 million people. This brings a further doubling in the amount of cataract surgery that needs to be done.

National Plan for Eye Care Development

The National Sub-Committee for Preven tion of Blindness (PBL) has been formed and a master plan for prevention of blindness and a national plan for eye care systems development is currently being imple-mented (1995–2001). These plans aim to provide eye care services in each region of Cambodia and to reduce blindness to less than 0.5% prevalence by the year 2005. Human resource development is considered the top priority in these plans. In addition, the plan also covers the development of facilities materials, sourcing of financial resources, management and specific control of locally endemic diseases for the different levels of eye care. The Ministry of Health, provincial and district health authorities and the National Sub-Commit tee for PBL, with assistance from INGOs, will play an important role in the implementation of the plans.

The national plan for prevention of blindness is now in the second phase of its implementation (1997–2001), which includes the training of doctors and nurses as Basic Eye Doctors and Basic Eye Nurses, overseas training of Ophthal mo logists and Ophthalmic Nurses, provincial training of Primary Eye Care Workers, and Optometrist Technicians. A national prim ary eye care programme is being implemented in 4 provinces.

VISION 2020: The Right to Sight


In October 1999, the Ministry of Health of the Royal Government of the Kingdom of Cambodia signed the global declaration of support for VISION 2020. Cambodia became the second country in Asia after China to sign this declaration in the Western Pacific Region. There is still the need, however, to mobilise a strong long-term political and professional commitment to eliminate avoidable blindness in Cambodia.

Disease Control


The main eye diseases being focused on within VISION 2020 are cataract, trachoma, childhood blindness, refractive errors and low vision and onchocerciasis (which is not present in Cambodia).

Cataract

Cataract in Cambodia accounts for 65% of blindness and 75% of visual impairment. Current estimates show that the backlog of cataract blindness is 80,000 with an annual incidence of over 19,500. Though the number of cataract operations (cataract surgical rate) performed in Cambodia has increased from 500 (60/million/year) in 1992 to 6000 (500/million/year) in 1999, this number is still about 30% of the annual incidence and the backlog of cataract blindness is increasing in magnitude. In order to address this problem, the delivery of cataract surgical services has to increase by 3–5 times the current output.

Preliminary results from cataract blindness prevalence surveys (1999) conducted on persons 50 years and older in Siem Reap province showed a blindness prevalence rate of 2.6%. The prevalence of cataract blindness was 1.96%. The cataract surgical coverage for eyes was 10.4% for VA<3/60, 2.6% for VA< 6/60 and 1% for VA<6/18. The overall cataract surgical rate for persons was 0.8%.
Based on the results from the survey, a cataract triangle was developed and is shown below. (http://www.jceh.co.uk/images/36_5.table1.gif)

Using the above model of the cataract triangle, it is estimated that the backlog of cataract surgery (VA <6/60) for the over 50s in Cambodia is about 108,000. (The over 50s represent 10% of the population.)



Within VISION 2020, appropriate strategies should address barriers to eye care, increase access to cataract surgical services and improve visual outcomes of cataract surgical services in Cambodia.

Trachoma

The magnitude of the trachoma problem is unknown in Cambodia. Preliminary surveys have shown that the prevalence of TF and TI in children under 10 years is 2.5%. In children under 5 years, the figure is approximately 3.2%. Similar surveys conducted in the northwest of Cambodia found the prevalence of TT to be 0.5% in women over 16 years. In the central region, a 1994 survey found TF to be 18.6% and TI to be 5.7% in children under 16 years and TT to be 4.3% in adults. Although trachoma is not a leading cause of blindness, hospital and eye unit reports indicate that the problem may be more widespread than originally thought. In fact, trachoma is a major cause of blindness among hospital patients. Furthermore, it is suspected that many people with trachoma will never show up at a health facility.

There is currently no official national trachoma control programme in Cambodia. However, many trachoma control activities are being carried out at all eye care levels. Current control measures are based on the SAFE strategy, integrated within PEC and PHC systems, but require further strengthening and support.
Cambodia is a member of the WHO Alliance for the Global Elimination of Trachoma (GET 2020), which falls under the umbrella of VISION 2020. A rapid assessment of trachoma and its risk factors is planned in 3 provinces with objectives to determine the occurrence of blinding trachoma, measure its magnitude and the severity of the problem. The findings of this assessment could serve as a base for the establishment of a National Trachoma Control Programme.

Childhood Blindness


Data on childhood blindness is limited. Surveys in the School for the Blind in Cambodia showed that corneal scarring from vitamin A deficiency, congenital cataract, high refractive errors and degenerative retinal diseases were the common causes of blindness and low vision.

Vitamin A deficiency (VAD) is still a problem of public health significance among Cambodian pre-school aged child ren and women. Surveys conducted in 1999 by Helen Keller International (HKI) in 5 provinces (Takeo, Kratie, Steung Treng, Siem Reap and Kompong Thom) showed night blindness prevalence rates of 1.8% among children aged 24–59 months and 4.3% and 6.8% among pregnant and non-pregnant mothers respectively. The surveys also showed that the total dietary intake of vitamin A among these groups is far below the recommended daily allowance and that vitamin A capsule distribution only reaches a small proportion of those who need it. Also, hospitals are reporting clinical cases of vitamin A deficiency.

Vitamin A capsule distribution started in Cambodia in 1994 and was integrated with the national immunization days (NIDs) in 1996 and into the National Expanded Programme for Immunization (EPI) in 1998. Whilst coverage was high with the distribution associated with NIDs, it has become much lower since it became part of the routine EPI.
The national micronutrient survey will determine the prevalence of vitamin A and iron deficiencies among children and mothers. The findings of this survey will assist in improving delivery mechanisms for vitamin A and in developing strategies to improve future programming for vitamin A.

Congenital Cataract


Data on the prevalence of congenital cataract among Cambodians is unknown. Hospital based data showed that congenital cataract of familial origin is common in Cambodia. Operations for congenital cata ract accounted for 2% of all ophthalmic operations within the eye units. Particular concerns are the late presentation of children for surgery and the lack of adequately trained personnel and equipment for paediatric surgery.
Within VISION 2020, in view of the number of years of blindness that ensue, strategies should include strengthening of PEC programmes within existing PHC systems, provision of equipment and training doctors in paediatric ocular surgery, and the establishment of optical and rehabilitative services.

Refractive Errors and Visual Impairment

Uncorrected refractive errors and aphakia account for about 10% of all causes of blindness in Cambodia. Hospital based statistics showed that uncorrected aphakia and refractive errors were causes of blindness in 6.5% and 0.6% of patients respectively. Statistics from screening camps in rural Cambodia (1999) show that 57% of patients with refractive errors require presbyopic corrections, followed by myopia (29%), hyperopia (13%) and aphakia (1%).

Vision screening programmes among school children in Battambang province (1997) showed that 1% of school children have refractive errors. Of these, myopia accounted for 70% of the cases. High errors of refraction (> + 3D) were found in 26% of these children. The other causes of poor vision among school children included corneal scar, cataract and amblyopia.
Survey reports in northwestern Cambo dia showed that the prevalence of visual impairment (bilateral) is 3.7%. The main causes of visual impairment include cataract, pterygium, macular degeneration, corneal scarring and uncorrected aphakia and refractive errors. In addition to private shops, only 4 public centres provide refraction and spectacles in Cambodia.
Within VISION 2020, affordable refractive services and corrective spectacles should be available within the PHC system through training of personnel, development of facilities for low cost production of spectacles, vision screening programmes in schools and establishment of low vision centres. Currently there are no trained personnel, facilities and equipment for the provision of low vision services in Cambodia. Centres for corneal banking, keratoplasty or lasers are non-existent.




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