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Changing thresholds for cataract surgery
  1. Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, UK

    Statistics from

    Editor,—We congratulate Hugh Taylor on his editorial1 in which he discusses the amount of cataract surgery that needs to be done. We were particularly interested by his calculations drawing attention to the effect of changing the visual threshold at which the decision to undertake cataract surgery is made.

    We have reviewed a series of eight audits of cataract surgery to determine the visual acuities at which patients were put on the waiting list for cataract extraction. The audits were designed to show surgical outcomes but they also list the visions at the point when the decision to operate was made. They include all patients during short periods between 1982 when intracapsular extraction without lens insertion was the norm and the first 6 months of 2000 when practically all cases were phacoemulsification through a clear corneal incision with a foldable lens. They are all based on the throughput of a single firm of a teaching hospital (Table 1).

    Table 1

    Visual acuity at listing for cataract extraction

    These results are heartening in that they show that the pool of dense cataracts resulting in visions of 6/60 or worse has decreased (from 77% in 1982 to 19% in 2000). They confirm that as surgical techniques have improved the demand for surgery at an early stage has dramatically increased. In the 1982 audit only 2.6% of cases saw 6/12 or better whereas by 2000 this figure had risen to 47.7%.

    We accept that visual acuity is far from being a comprehensive measure of visual disability but none the less it is useful as an indicator of trends. The trend is clearly towards earlier cataract surgery and it is likely to be maintained resulting in increasing surgical volumes. The answer to Taylor's question, “how much surgery do we have to do?” is more and still more. The problem then becomes partly political in that governments decide on maximum waiting times for surgery with the effect that it becomes difficult to prioritise those patients with a serious degree of cataract over those who are simply suffering inconvenience.


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