One of the greatest challenges facing world ophthalmology today remains the unacceptably high prevalence of operable cataract blindness in the developing world. The establishment of national and international cataract programmes, frequently funded and supported by international agencies, has achieved a steady increase in the number of cataract operations performed, but current levels remain too low to tackle the backlog of cataract blind, estimated to be 16–20 million, and to stem the rising world incidence consequent on the aging population.

As understanding grows of the dynamics of the problem of cataract blindness, it is increasingly realised that solutions resting on cataract numbers alone are insufficient, and that strategic planning is needed to effect change across a complex web of interrelated constraints if the goal of a high volume sustainable cataract programme is to be achieved.

Fundamental are questions of quality of surgical outcome and cost. As eloquently illustrated by Pokharel et al in two papers in this issue of the journal (pp 600 and 606), cataract programme strategies based on intracapsular cataract extraction (ICCE) and the provision of aphakic spectacles, even when the service is free, fail to significantly affect the blindness prevalence. This is not only because cataract coverage is insufficient, but also because an estimated 10–15% of patients remain socially blind (visual acuity <3/60) after the surgery.1 Apart from the failures due to incorrect diagnosis (a patient blind with cataract but not because of cataract) and operative complications, this can be attributed to the difficulties of the refractive correction of aphakia. When visual outcome includes an assessment of quality of vision and visual function, a more encompassing and realistic measure than Snellen visual acuity, it is even more apparent that the results of ICCE/spectacle correction are inadequate. It has been estimated, for example, that to function as well as a pseudophake with 6/18 vision, a corrected aphake must have a visual acuity of 6/6 or better.2 Postoperative aphakia is furthermore inappropriate in the unilaterally blind. The visual outcome failure of traditional cataract programmes to correct blindness is reflected by the estimated 30–50% of aphakic patients who chose not to wear the glasses provided free nor to replace them when they became lost or damaged.1 3

Given the importance of quality of outcome on the effectiveness of the cataract surgery to correct blindness, there are now strong advocates for the introduction of treatment strategies that involve insertion of an intraocular lens (IOL). Many workers have reported the efficacy and safety of high volume cataract surgery with IOL insertion, both anterior and posterior chamber, in clinic and outreach eye camp settings in the developing world.4-6 Previous constraints of cost and affordable technology that impeded the application of this technique, long adopted in the Western world, to the developing world have now been largely overcome. High quality one piece posterior chamber intraocular lenses are now available at a unit cost of US$10 as are sturdy portable microscopes. Of fundamental importance are skilled medical staff, be they doctors or cataract surgeon “technicians”, and priority should be increasingly given by national health services and international organisations on training and skill transfer. This can be achieved most effectively by programmes which “train the trainers”, local medical staff, who can then provide ongoing supervision and support.

Fundamental to the sustainability of cataract programmes and to overcoming patient barriers to the surgery are questions of cost. There are now several highly successful models of cataract programmes based on cost recovery, particularly that in Aravind, India.7These models take into consideration the unit cost of surgery including transport and disposables, as well as operational fixed costs, and function through the charging of a scale of patient fees and incorporating subsidies for the destitute. They aim to cure cataract before severe blindness has developed and while the patient is economically productive with some resources to afford the surgery. For these models to work, operational and infrastructure aspects must be addressed, most importantly the management of cataract services to optimally utilise existing resources.

Patient barriers to cataract surgery are also important. Although some of these barriers, such as availability and proximity of surgical facilities, can be addressed through a cataract programme which includes outreach, the chief barriers of ignorance, low motivation, and impoverishment remain difficult to overcome. Educative and advertising drives are important but marketing relies on quality of surgical outcome: perhaps the most effective motivator is a previously blind patient following a successful vision restorative operation who educates and motivates others.

The challenge remains in cataract blindness programmes to increase operation numbers, while improving the quality of the visual outcome and decreasing the cost. It is a challenge worth undertaking, by ophthalmologists in the Western world, as well as those in the developing world.