Surgical treatment for cataract caused by aging changes in the lens which reduce its transparency and leads to visual impairment

Cataract is a major cause of global blindness, accounting for 50% to 80% in developing countries. The number of people blind from cataract is expected to rise due to the increase in life expectancy. Aging causes changes in the lens protein leading to opacification of the lens. These changes are often bilateral although maybe asymmetric. Symptoms from cataracts include glare, blurred vision, progressive decrease in visual function and blindness. Surgery is currently the only treatment option once the lens has opacified and vision is decreasing. The indication for surgery is based on whether the patient's reduced visual function interferes with their quality of life. Different surgical techniques have been developed to remove the cloudy lens which is replaced either by an intraocular lens (positioned in the posterior chamber or the anterior chamber of the eye), aphakic glasses or contact lens. There are four main forms of cataract extraction surgery: intracapsular (ICCE), extracapsular (ECCE), phacoemulsification (PHACO) and manual small incision (MSICS). The review authors searched the medical literature and identified 17 randomised controlled trials (9627 participants) investigating the different surgical interventions. Six of these trials suggested that PHACO gives a better outcome than ECCE. They suggest a better uncorrected visual acuity (UCVA) following PHACO than ECCE but the majority of the trials showed no difference in best corrected visual acuity (BCVA) between the two groups. The costs per procedure were not markedly different between the two techniques in a UK based study, however, a Malaysian study showed ECCE to be significantly cheaper. A study comparing MSICS and ECCE, advocated MSICS as the procedure of choice due to equal costs and better visual results. Two studies compared the results of PHACO and MSICS. Phacoemulsification having a significantly higher proportion of patients with UCVA > 6/18 (81.1% versus 71%) but there was no difference in BSCVA. Trials comparing costs of PHACO and MSICS are important for future research. Manual small incision surgery offers an alternative technique in developing countries as it provides acceptable visual outcomes when compared to PHACO yet is likely to be more economical as it avoids the initial outlay of costs of PHACO. It is important to remember that the studies in this review were based in a variety of countries and situations (hospital based or cataract camps); a knowledge of the setting is vital before drawing conclusions from the data.