Academic journal article Bulletin of the World Health Organization

Preoperative Visual Acuity among Cataract Surgery Patients and Countries' State of Development: A Global Study/ Acuite Visuelle Pre-Operatoire Des Patients Subissant Une Operation De la Cataracte et Etat De Developpement Des Pays : Une Etude mondiale/Agudeza Visual Preoperatoria En Los Pacientes Sometidos a Cirugia De Cataratas Y Estado De Desarrollo De Los Paises: Un Estudio Global

Academic journal article Bulletin of the World Health Organization

Preoperative Visual Acuity among Cataract Surgery Patients and Countries' State of Development: A Global Study/ Acuite Visuelle Pre-Operatoire Des Patients Subissant Une Operation De la Cataracte et Etat De Developpement Des Pays : Une Etude mondiale/Agudeza Visual Preoperatoria En Los Pacientes Sometidos a Cirugia De Cataratas Y Estado De Desarrollo De Los Paises: Un Estudio Global

Article excerpt

Introduction

Blindness is both a cause and an outcome of poverty. (1) Cataract, defined by the World Health Organization (WHO) as a visual acuity (VA) of less than 3/60 in the better eye, is the leading cause of blindness in the world. It affects approximately 18 million people, 90% of them in low- and middle-income countries. (2) A recent study in three countries has demonstrated that successful cataract surgery in previously blind individuals can improve a household's economic status. This suggests that cataract surgery should be an integral part of strategies designed to reduce poverty. (3)

Thanks to improvements in surgical techniques for cataract extraction (e.g. sutureless microsurgery and use of intraocular lenses with a wide range of powers), surgery can be performed as an outpatient procedure under local anaesthesia and can restore normal VA almost immediately. It can also be offered much earlier, so that blindness can be prevented even in developing countries, where these techniques are now the norm. Clearly cataract surgery is practised under very different circumstances in different parts of the world and although its cost varies enormously, it is one of the most cost-effective of all health interventions. (4) Thus, cataract surgery is a priority for VISION2020: the Right to Sight initiative (http://www.vision2020.org), a partnership between the World Health Organization (WHO) and other agencies working in eye care, including the International Agency for the Prevention of Blindness (IAPB). (5,6)

Over the last two decades, increased demand has led to a marked increase in the number of cataract operations in most countries, and surgery is being performed earlier on average because patients' needs and the results that they expect to obtain from surgery have changed. From a public health standpoint, this change in the indications for surgery dramatically affects the number of people eligible for surgery. In Australia, for example, reducing the visual impairment threshold from 6/60 to 6/12 would increase the number of people eligible for surgery by nearly fivefold. (7) Concerns have been raised that in some high-income countries too many cataract operations are being performed, (8) often to correct refractive error rather than to reverse visual impairment.

The cataract surgery rate (CSR), which represents the number of cataract extractions performed per million population per year in a given location, is a key indicator for monitoring eye care services. To reduce visual impairment from cataract the CSR must be greater than the incidence rate of cataract. (9)

According to WHO, whose estimates of country-level CSR are the best available, (10) in 2004 (the most recent published data) high-income countries had a CSR ranging from 4000 to 6000, whereas in most of Africa, China and the poorer countries of Asia the CSR was often less than 500. CSR has increased substantially since then, but to understand what currently constitutes an operable cataract it is best to examine the local surgical case mix (i.e. the range of patients' visual acuities before cataract surgery and the number of first-eye surgeries performed).

This is the first study undertaken by a newly formed research network of ophthalmologists whose members were asked to collect information about the cataract surgery case mix in their hospitals. The purpose of the study was to assess variations in case mix by place and demographic characteristics, and to describe the relationship between preoperative VA, country development level and national CSRs.

Methods

The International Eye Research Network (IERN), whose members are listed in Appendix A (available at: http:// www.iceh.org.uk/download/attachments/15827118/iem-participants.pdf), is a newly established international collaboration of ophthalmologists. Recruitment was as follows: First, alumni of the Masters in Community Eye Health programme at the London School of Hygiene & Tropical Medicine (LSHTM) were approached by e-mail. …

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