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Abstract
Objective To evaluate national trends of trabeculectomy, aqueous shunts and cycloablation performed in Scotland, England and Wales from 1993 to 2012.
Methods The annual numbers of trabeculectomies and aqueous shunts carried out between 1993 and 2012 were obtained from national Scottish, English and Welsh National Health Service databases. The annual rates of trabeculectomy, aqueous shunts and cycloablation were calculated per 100 000 of the population and analysed in the following age groups: 0–14 years, 15–59 years, over 60 years.
Results The highest annual rate of trabecuelctomy was in 1995, this was followed by a sharp decline and subsequent stable rates since 2000. The total annual rates of aqueous shunts have increased more than sixfold from 2003 to 2012. In the 0–14 years age group from 2003 to 2012 the ratio of trabeculectomy to aqueous shunts has reversed; trabeculectomy rates have decreased while rates of aqueous shunts have increased. From 2003 to 2012, rates of cyclocryotherapy have reduced while rates of photocoagulation to the ciliary body have doubled.
Conclusions Trabeculectomy is the most commonly performed glaucoma operation. Aqueous shunts are rapidly increasing in the surgical management of glaucoma. During the study period, the ratio of trabeculectomy to aqueous shunts has reversed in the younger age group (0–14 years). Rates of cyclocyrotherapy to the ciliary body have dramatically declined while laser photocoagulation to the ciliary body is gaining wider acceptability.
- Glaucoma
- Drugs
- Field of vision
- Intraocular pressure
- Optic Nerve
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Introduction
Glaucoma is the leading cause of irreversible blindness in the world; it accounts for 2% of visual impairment and 8% of global blindness.1 The impact of glaucoma management on ophthalmic services throughout the UK cannot be understated; glaucoma accounts for a million NHS visits per annum and 9%–12% of visual impairment registrations in people over 65 years.1
Trends in glaucoma surgery have been influenced by advances in topical ocular hypotensive agents.2 ,3 Following the introduction and widespread use of prostaglandin analogues and carbonic anhydrase inhibitors there was a rapid fall in trabeculectomy rates in the late 1990s throughout the UK.2–5 Glaucoma drainage devices or aqueous shunts, the preferred term used by the American National Standards Institute, were traditionally reserved for cases of refractory glaucoma where trabeculectomy had failed or was likely to fail.6 A growing experience of these devices has led to wider clinical indications, however, there is no current data on trends in their usage.6 ,7
This study aims to give an overview of the changes in trends of trabeculectomy and aqueous shunts over the past 20 years throughout Scotland, England and Wales. Trends of trabeculectomy, aqueous shunts and cycloablation are analysed by age group over the past 10 years from 2003 to 2012.
Materials and methods
The operating procedure code supplements 4 were identified for the following procedures:
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Trabeculectomy C60.1
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Insertion of tube into anterior chamber tube C60.5 (aqueous shunts)
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Cryotherapy to ciliary body C66.3
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Laser photocoagulation to ciliary body C66.4
The following data from Information Statistics Department Scotland, Hospital Episode Statistics England and Patient Episode Database Wales were collected:
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The annual gross numbers of trabeculectomy and aqueous shunts carried out over 20 years from 1993 to 2012 in Scotland, England and Wales.
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The annual numbers of trabeculectomy, aqueous shunts, cryotherapy to ciliary body, and laser photocoagulation to ciliary body over 10 years from 2003 to 2012. These data were analysed into the following age groups; 0–14 years, 15–59 years, over 60 years. These particular age groups were chosen, as Hospital Episode Statistics displays data in this way and Information Statistics Department and Patient Episode Database Wales were able to produce the data in these age groups by special request.
Midyear population estimates for Scotland, England and Wales were obtained from government websites.8 ,9 Annual rates of the above mentioned procedures per 100 000 of the population were calculated.
Results
The annual rates of trabeculectomies and aqueous shunts carried out in total in Scotland, England and Wales from 1993 to 2012 are shown in figure 1. The highest annual rate of trabeculectomy was in 1995 reaching 36.47 per 100 000 of the population. This was followed by a sharp decline in annual trabeculectomy rates, and from the year 2000 onwards the rates have been relatively stable. Despite the overall decline in trabeculectomy rate, trabeculectomy is still the most commonly performed glaucoma operation; in 2012 the ratio of trabeculectomy to aqueous shunt was approximately 10:1 in the over 60s age group (table 1). The total numbers and rates of trabeculectomy from 2003 through 2012 broken down by age group are shown in table 1. Rates of trabeculectomy have decreased in the 0–14 years age group and remained stable in those aged 15–59 years. In those over 60 years of age, trabeculectomy rates are stable with a small increase during 2011 and 2012.
Total number of trabeculectomies performed per annum in Scotland, England and Wales by age group: 0–14 years, 15–59 years, over 60 years
National rates of trabeculectomies and aqueous shunts in Scotland, England and Wales (1993–2012). Please note the differences in scale on both y-axes.
There was little variation in the annual rates of aqueous shunts during the 1990s (figure 1). From the year 2003 onwards there has been a steady annual increase in aqueous shunts, the steepest increase from 2009 through 2012. The total rate of aqueous shunts in 2012 was sixfold higher than in 2003. The rates of aqueous shunts have increased in all age groups, more so in those over 60 years (table 2). In the 0–14 years age group from 2003 to 2012 the ratio of trabeculectomy to aqueous shunts has reversed; trabeculectomy rates have fallen by approximately 34% while rates of aqueous shunts have more than doubled. In 2012, there were twice as many aqueous shunts performed in children than trabeculectomies (table 1).
Total number of aqueous shunts performed per annum in Scotland, England and Wales by age group: 0–14 years, 15–59 years, over 60 years
From 2003 to 2012, rates of cryotherapy to the ciliary body have decreased in all age groups (figure 2), with the largest decline in the over 60s group. During the same time period laser photocoagulation to the ciliary body has approximately doubled in those over 60 years and stayed relatively stable in younger age groups (figure 3).
National rates of cryotherapy to the ciliary body in Scotland, England and Wales by age group (2003–2012).
National rates of laser photocoagulation to the ciliary body in Scotland, England and Wales by age group (2003–2012).
Discussion
The aim of this paper was to achieve a realistic impression of the current practices in glaucoma surgery throughout Scotland, England and Wales. Various studies documented a rapid decline in trabeculectomy rates from the late 1990s; this study aims to identify if these trends have been sustained and investigate the impact on other glaucoma surgeries.1–5 ,10
These data are the first to show that combined rates of trabeculectomy from Scotland, England and Wales have remained stable up to and including the year 2012 (figure 1). The latest review from England confirmed the annual rate of trabeculectomy has remained stable from 2005 through 2009.11 The most recent Scottish data showed decreasing trabeculectomy rates up to 2004.2 Our study shows that from 2003 to 2012 the overall trabeculectomy rates have remained stable from 9.06 to 10.76 per 100 000, respectively. There has been a small increase in national trabeculectomy rates per 100 000 in those over 60 years of age from 34.83 in 2010 to 37.95 in 2012 (table 2). An increase in trabeculectomy rates was reported in Leicester from 7.57/100 000 in 2005 to 18.87/100 000 in 2009.12 This increase in trabeculectomy rate was disputed by Keenan et al who suggest that disparities in population demographics, prevalence and severity of glaucoma and variations in management will account for differences between national and local trends.10 The small increase in national trabeculectomy rates observed in this study may be due to demographic shifts in an aging population, however, it may represent a delay in surgery rather than prevention in surgery secondary to glaucoma drops.2 ,5
Throughout the 1990s the rate of aqueous shunts was relatively stable (figure 1). This reflects the rarer indications for aqueous shunts: refractory glaucoma, previous failed filtration surgery, rubeotic glaucoma, traumatic glaucoma, inflammatory glaucoma and congenital glaucoma.6 Rates of aqueous shunts have increased from 2003 to 2012 in all groups with the largest increase in those over 60 years (figure 1 and table 2). Data from America and Canada show similar results: there was an increase of 184% in tube implantation in America from 1995 to 2004 and a 12-fold increase in Canada between 1992 and 2002.13 ,14 An aging population requiring repeat procedures and increased subspecialisation of surgeons will have contributed to the national increasing trends in aqueous shunts.15 Lack of information on the indications for aqueous shunt surgery limits this analysis.
Five-year results from the Tube versus Trabeculectomy study found aqueous shunts and trabeculectomy produced sustained intraocular pressure (IOP) reduction and both resulted in the same number of glaucoma medications required in the long term. Tubes had a higher rate of surgical success, the probability of failure was 29.8% in the tube group and 46.9% in the trabeculectomy group.16 Trabeculectomy had higher rates of early postoperative complications but both procedures had similar rates of late postoperative complications. While there is no current evidence to support the superiority of either tubes or trabeculectomy, it is clear that the role of tubes has expanded beyond those with refractory glaucoma.17
Our data suggest that in children (0–14 years) there has been a national trend towards increased use of aqueous shunts and decreased use of trabeculectomy (tables 1 and 2). Comparison of aqueous shunts and trabeculectomy with mitomycin C in children <24 months showed that while aqueous shunts resulted in lower IOP, they were also associated with more frequent postoperative complications (45.7% with aqueous shunts vs 12.5% with trabeculectomy).18 The most common complication was tube-cornea touch requiring return to theatre in 34.5% of cases. While trabeculectomy has the advantage of being a more familiar operation it is not straightforward in children; distorted limbal anatomy can lead to complications such as ciliary body and iris incarceration and vitreous loss.19 Utilisation of the superior conjunctiva is less than ideal given the longer life expectancy and the likely need for further surgery.19 In addition, the use of antimetabolites is associated with hypotony, choroidal detachment and late-onset endophthalmitis in congenital glaucoma.18 ,19
Ciliary body ablation has been traditionally reserved for refractory glaucoma to lower IOP.20 Cyclocryotherapy is non-invasive and easy to perform; however, side effects of visual loss and phthisis were as high as 30% and 11.8%, respectively, in one case series.21 The rates of cyclocryotherapy performed in the UK declined between 2003 and 2012 with the steepest decline in those over 60 years of age (figure 2). During the same 10 years, rates of laser cycloablation to the ciliary body more than doubled in the over 60 s age group while remaining low in younger age groups (figure 3). Initially reserved for refractory IOP in eyes with poor vision, transscleral diode laser has potential for adverse effects on visual functioning.20 ,22 ,23 More recent reports have reported efficacy in patients with good visual acuity, therefore widening its acceptance and gaining support for its earlier use in those with less advanced glaucoma and better visual potential.22 ,23 A recent British survey on transscleral diode photocoagulation revealed 60% of consultants perform cyclodiode at any level of visual acuity with only 12% reserving it for vision of 6/60 or worse.24 The UK national cyclodiode survey in 2008 showed only 4.1% of responders performed endoscopic cyclodiode.24 We anticipate that in the time elapsed since this study there will be a higher number of surgeons performing endoscopic cyclodiode photocoagulation, however, the number will still be small in relation to transscleral diode laser. A limitation of clinical coding means that there is no clear differentiation between transscleral and endoscopic laser photocoagulation.
Rates of laser trabeculoplasty increased in Canada between 2001 and 2004 coinciding with the introduction of selective laser trabeculoplasty.25 In contrast, rates of laser trabeculoplasty reduced by 60% in England from 1998 to 2004.4 To our knowledge there is no subsequent data on the frequency of trabeculoplasty from the UK. We elected not to investigate the numbers of laser trabeculoplasty as these procedures are not carried out in theatre, and so they are more prone to coding errors. A preliminary investigation into rates of trabeculoplasty showed large discrepancies and therefore was not included in the study.
This study has limitations: as only NHS episodes are included, the accuracy of our data relies on the accuracy of clinical coding. We analysed only the last 10 years from 2003 to 2012 by age as it is during this period the rates of aqueous shunts increased. We did not seek data on other procedures such as deep sclerectomy and minimally invasive glaucoma surgery because the number of these performed is small and changes in trends would be unlikely.
Conclusions
Our results demonstrate the most recent collective trends from Scotland, England and Wales in glaucoma surgery. Trabeculectomy is still the most commonly performed glaucoma operation. Trabeculectomy rates have overall remained stable since 2003; in contrast, there has been a rapid rise in the use of aqueous shunts particularly in the older age group. The ratio of trabeculectomy to aqueous shunts has reversed in children over the last 10 years with increasing use of aqueous shunts. Cyclocryotherapy has been supplanted by laser photocoagulation to the ciliary body; rates of cyclophotocoagulation are increasing in the over 60s age groups and remain stable in younger patients. The changing trends in glaucoma surgery observed in this study are valuable for service planning, allocation of resources and training.
References
Footnotes
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Contributors CMu: main author; CMa, CC: critical revising; SO: statistics.
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Funding This study was supported by the Speed Pollock Memorial Trust.
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Competing interests None.
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Provenance and peer review Not commissioned; externally peer reviewed.
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