Sir,

We previously reported a sharp decline in the annual rate of trabeculectomy operations in England: from a peak of 38.7 episodes per 100 000 population in 1995/6 towards a plateau around 11 episodes per 100 000 in 2003/41 (where 2003/4 refers to the NHS financial year 1st April 2003 to 31st March 2004). As discussed previously,1 this was principally due to the introduction of new topical agents with improved control of intraocular pressure, and was accompanied by similar decreases in trabeculectomy rates throughout Britain, Europe, Canada, and the United States of America. Tatham and Sarodia2 recently described an increase of 149% in the annual number of trabeculectomy operations at Leicester Royal Infirmary, from 71 in 2005 to 177 in 2009, and suggested that the national decline in trabeculectomy may have begun to reverse.

We have used recent data to study trends in the number and rate of hospital episodes of trabeculectomy in England as a whole (Table 1 and Figure 1). Hospital episode statistics (HES) data sets were analysed using the operation code C60.1 in OPCS4, recorded in any position on the HES record. Using record linkage, we also analysed the number (and rate) of individual people who underwent trabeculectomy, as explained previously;1 linked data were available for 1998/9–2008/9.

Table 1 Annual number of trabeculectomy operations, and annual rate of trabeculectomy operations per 100 000 population, in England from 1989/1990 to 2009/2010
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Figure 1
figure 1

Hospital admission rates per 100 000 population for trabeculectomy: English national data from 1989/90 to 2008/9 measured as episodes and people per year.

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The annual rate of trabeculectomy has remained stable in England over the past 5 years. It actually decreased from 10.6 episodes in 2004/5 to 10.2 in 2008/9, thereafter increased slightly to 11.0 in 2009/10. Expressed as numbers, trabeculectomy operations have also remained approximately unchanged over the past 5 years at around 5300 per year, with a small upturn from 2008/9 to 2009/10.

Little evidence is seen as yet for any notable increase in the rate of patients undergoing trabeculectomy in England as a whole. A modest rise in the number of patients requiring surgery might be anticipated owing because of demographic shifts towards an older population,3 but again no convincing evidence for a sustained increase in the number of patients undergoing surgery is evident so far.

Many factors may account for differences between national trends and those within specific geographical areas or clinical units. Disparities in population demographics (particularly age and ethnicity) may mean that the prevalence and severity of glaucoma (requiring surgery) will vary between areas. Local variation may exist in medical vs surgical decision making in glaucoma management; in the context of increasing subspecialisation in glaucoma detection and treatment, this may be influenced by the proportion of glaucoma patients overseen by a glaucoma specialist vs a general ophthalmologist. Despite the backlog of patients awaiting glaucoma review in England,4 it is important that every suitable patient should be offered glaucoma surgery where appropriate. In addition, the range of laser and surgical therapies for glaucoma has increased in recent years, and important studies5, 6, 7, 8 are continuing to influence target intraocular pressures and therapeutic options. In particular, an increase in the rate of patients undergoing laser trabeculoplasty, cyclophotocoagulation, non-penetrating glaucoma surgery, and drainage tube surgery may have contributed to the decline and plateau observed in the national trabeculectomy rate in recent years. Further studies are warranted to examine national trends for all these laser and surgical interventions in concert, ideally using prospectively collected data.