Current situation There are estimated to be almost 18 million people who are bilaterally blind from cataract, representing almost half of all causes of blindness due to eye diseases globally. The proportion of blindness due to cataract among all eye diseases ranges from 5% in western Europe, North America and the more affluent countries in the Western Pacific Region to 50% or more in poorer regions. The main non-modifiable risk factor is ageing. Other frequently associated risk factors are injury, certain eye diseases (e.g. uveitis), diabetes, ultraviolet irradiation and smoking. Cataract in children is due mainly to genetic disorders. Visually disabling cataract occurs far more frequently in developing countries than in industrialized countries, and women are at greater risk than men and are less likely to have access to services. The cataract surgical rate—the number of cataract operations per million population per year—is aquantifiable measure of the delivery of cataract surgical services (Annex V). It is meaningful, however,only when it includes all cataract operations performed in a country, including those in the private sector and during outreach, and when the population size and age structure can be defi ned. Cataract surgical coverage indicates the number of individuals with bilateral cataract causing visual impairment, who have received cataract surgery on one or both eyes, in other words, the proportion who were eligible for surgery and who received it. This indicator is used to assess the degree to which cataract surgical services meet the need. The data are obtained from population-based surveys or rapid assessments. Software for monitoring and assessing the quality of cataract surgery are available, and VISION 2020 encourages the monitoring of quality so that performance continues to improve. There are two main surgical techniques for removing a cataract: extracapsular cataract extraction and phacoemulsifi cation. In extracapsular cataract extraction, the lens capsule is opened and the nucleus of the lens and the cortex are removed, leaving the posterior capsule in place. This can be done through a small incision, which does not usually require sutures, or through a standard incision closed by removable sutures. In phacoemulsifi cation, an ultrasound probe is used to fragment the lens, which is aspirated through a small incision. There are three ways of correcting aphakia, an eye with a surgically removed lens: spectacles, contact lenses or an intraocular lens. Thick spectacles are required for patients who have undergone intracapsular extraction, and this technique was widespread in the past. Contact lenses are not appropriate in most settings. An intraocular lens, implanted after the cataract has been removed, is the optimal method, as it eliminates the use of thick spectacles. Nevertheless, light spectacles are often necessary to compensate the loss of accommodation. Achievements Cataract is included in most national plans for the prevention of blindness, and cataract surgical rates are increasing in many countries. Cost-effective surgical techniques have been developed and tested and are being improved continuously (e.g. small-incision cataract surgery and use of good-quality,low-cost intraocular lenses). Limitations The main limitations are lack of resources and political will to address cataract blindness as a global public health issue. In many poor rural districts, there is a dramatic lack of eye-care services, and, even where they are available, their quality is not always satisfactory. High-quality low-cost cataract service models are widely used in a number of countries, but their uptake in low-income countries is slow, due to local conditions such as the infl uence of the private sector and the presence of more expensive products on the market. The main barriers to uptake of cataract surgery in poor communities are lack of awareness, poor quality of service, high cost of treatment and limited access. VISION 2020 Aim to eliminate blindness due to cataract VISION 2020 Objective to provide cataract surgical services at a rate adequate to eliminate the backlog of cataract over a number of years, at a price that is affordable for all people, both rural and urban, in an equitable manner, and with a high success rate in terms of visual outcome and improved quality of life Strategies Create demand for services by overcoming barriers to the uptake of cataract surgical services.The approaches recommended include enlisting community health and rehabilitation workers to identify people with cataract and to provide follow-up and rehabilitation after surgery. Priority should be given to patients who are bilaterally blind from cataract; however, patients should be encouraged to seek treatment before becoming blind, thereby reducing their dependence on the family and society, and this should be taken into consideration in calculating the desired cataract surgical rate. Develop and mobilize local manpower and resources to provide cataract services. Training and use of mid-level personnel will allow ophthalmologists more time for surgery. Private ophthalmologists should be actively involved. Promote services at a cost that all patients can afford. This might require bulk purchase of consumables and tiers of payment, whereby fees from high-income patients are used to subsidize services for low-income patients. Introduce cost-effective methods and techniques for cataract surgery. Promote services that are close to where people live. Outreach to remote areas should be conducted where appropriate. Screening for new cases is acceptable only when surgical services are in place so that newly identifi ed patients can be treated. Short-term or one-time surgical camps are not appropriate, except under specific circumstances. Promote high-quality surgery with a good visual outcome. Intraocular lenses should be used for all patients, unless contraindicated. Monitoring of the outcome of surgery should be encouraged to improve quality. Provide facilities and promote practices and behaviour that are acceptable to patients. Ensure complementarity with governmental and nongovernmental service delivery. Targets Cataract surgical rate: Each county’s national plan for the prevention of blindness should include achievable targets for increasing the cataract surgical rate to the desired level, which should be the rate required to eliminate cataract-related, severe visual impairment calculated on the basis of data for the local population. The rate will depend on the prevalence of cataract causing visual impairment, the visual acuity recommended for eligibility for surgery and demographic trends. Cataract surgical coverage: Ultimately, the highest possible cataract surgical coverage (at least 85%) should be reached. Monitoring cataract prevalence at district and subnational level and using cost-effective methods for assessing cataract surgical coverage will allow identifi cation of gaps, so that services are targeted to areas and subgroups at greatest need. Quality of cataract services: WHO targets for the quality of cataract surgery will be met, i.e. at least 85% of eyes achieve 6/18 or better presenting visual acuity postoperatively (22). Indicators national (regional or global) prevalence of blindness due to cataract, obtained from population-based epidemiological studies or rapid assessment; national, district or subnational cataract output (number of cataract operations per year) and cataract surgical rates (number of cataract operations per million population per year); cataract surgical coverage (proportion of need that is being met, for example, the proportion of aphakia or pseudophakia in relation to blindness due to cataract in representative samples of the population); proportion of cataract surgery with intraocular lenses (intraocular lens implantation rate); and quality of cataract surgery in representative samples of the population, evaluated, for instance, in rapid assessments of cataract surgical services.
Posted on: Mon, 15 Jul 2013 07:06:18 +0000
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