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The volume of various glaucoma procedures may fluctuate with disease prevalence, introduction of new therapies, changes in practice patterns, and number of surgeons. Evaluating trends in different glaucoma procedure utilization rates is critical for health policy planning. Given the recent introduction of micro-invasive glaucoma surgery (MIGS), prior studies have not assessed its influence on the volume of different glaucoma procedures. We aim to evaluate trends in the yearly number of common glaucoma surgical and laser procedures performed in Alberta from 2003 to 2018.
We conducted a retrospective, population-based analysis. The yearly number of all glaucoma-related procedures claimed under the Alberta Health Care Insurance Plan from 2003 to 2018 were obtained using health service codes. These data reflect all paid claims to physicians for services provided to Alberta residents. Specifically, we were interested in the following procedures: trabeculectomy, glaucoma drainage device implantation, MIGS, laser trabeculoplasty, ciliary body ablation, surgical iridectomy, iridoplasty, and laser peripheral iridotomy. Research ethics board approval was not required for this study.
Estimates of Alberta's annual population, stratified into 5-year age groups, were obtained from Statistics Canada.
This model is a composite of 11 major epidemiological prevalence surveys in Western nations and is controlled for population age. The yearly number of procedures per 1000 persons with POAG were then calculated.
From 2003 to 2018, the population in Alberta increased over 30% and the median age of Albertans increased from 35.3 to 36.9 years. The proportion of the population older than 65 years increased from 10.3% to 12.8%. Correspondingly, the prevalence of glaucoma was estimated to increase from 0.51% to 0.60%. The number of ophthalmologists increased 23% from 88 to 108, and rates of all glaucoma-related procedures increased 4-fold during this period (Table 1). Trends of specific glaucoma surgical and laser procedures performed each year are illustrated in Figure 1. Rates of glaucoma drainage device (GDD) implantation increased 3-fold from 2007 to 2010 and stabilized thereafter. All glaucoma operations, except laser, remained relatively stable from 2003 to 2009 and rose thereafter until 2014, potentially reflecting the billing of MIGS procedures under pre-existing codes before the introduction of its individual code. After the introduction of separate ab-externo and ab-interno procedure codes in 2014, both trabeculectomy and MIGS rates increased more than 60% from 2014 to 2018. Trabeculectomies and MIGS accounted for 41% and 34% of all glaucoma-related surgeries, respectively. Anterior chamber laser rates increased 6-fold from 2004 to 2014. After the introduction of separate laser trabeculoplasty (LT) and laser peripheral iridotomy (LPI) codes in 2014, LTs increased 35% and LPIs increased 194% over the subsequent four years. Ciliary body ablation rates increased 19-fold from 2004 to 2018.
Table 1Yearly number of glaucoma surgical and laser procedures performed per 1000 persons with primary open angle glaucoma in Alberta from 2003 to 2018
Health service code
Service code description
Glaucoma implant procedures with reservoir shunts
Glaucoma (all major operations) except laser
Trabeculectomy or major revision of trabeculectomy
Repeat trabeculectomy within 28 days
Ab-interno angle surgery (stent, trabectome, or similar) for adult open-angle glaucoma
In Alberta, trabeculectomy remains the most commonly performed glaucoma surgical procedure and accounts for 41% of glaucoma-related surgeries in Alberta. This is similar to trends in Ontario and the UK where rates of trabeculectomies remained stable from 2002 to 2012.
These trends indicate a potential shift in surgeon preference toward drainage devices compared with trabeculectomies.
A trend was noted towards increasing rates of MIGS and ciliary body ablation procedures, suggesting a shift toward less invasive procedures. MIGS has become the second most commonly performed glaucoma surgical procedure. Currently, Alberta and Quebec are the only two provinces in which separate MIGS billing codes exist. As a result, prior published studies have not assessed MIGS procedures as a separate entity, but instead as part of the broader category of tube shunt procedures. Although there is no published data specifically examining the rate of MIGS surgeries in Quebec, Kansal et al. evaluated trends in glaucoma filtration procedures as a surrogate index for MIGS surgeries.
Similar to our data, they found that all glaucoma filtration surgeries declined from 2003 to 2008, and then rose until 2014. These procedures then decreased, coinciding with the introduction of MIGS billing codes in 2014. However, in Quebec, all glaucoma filtration surgeries steadily declined from 2003 to 2016 while GDD implantation rose during that period. Given a separate MIGS billing code was only introduced in 2015, it is possible these data do not yet reflect the trend seen in Alberta.
The yearly prevalence of POAG in Alberta was estimated by applying a composite glaucoma prevalence curve developed from multiple population-based surveys.
However, the epidemiological studies used for this model included mainly white Caucasian populations from Europe, Australia, and Baltimore. Because the population in Alberta is more diverse including many ethnic groups, and the prevalence of POAG is higher in Blacks and Latinos, our calculated prevalence of POAG may be an underestimate. Furthermore, this model applies only to POAG and does not capture the prevalence of all glaucoma.
A challenge encountered during interpretation of these results is the lack of specificity in health service codes. As all filtration surgery except GDD was billed under “glaucoma (all major operations), except laser” before 2014, it is difficult to comment on rates of trabeculectomy and MIGS separately. Similarly, with laser procedures, an overarching “anterior chamber laser” code was used for both LT and LPI before 2014, despite their application for different glaucoma types. We also recognize the transition of several codes in 2014 as a major limitation of our analysis. These limitations highlight the importance of implementing new billing codes in a timely manner, and the need for additional studies in the future once these codes are established into practice. This will allow us to better understand the role of different glaucoma procedures in disease management. In addition, new codes allow reimbursement to appropriately reflect the intensity associated with newer MIGS procedures and have important cost implications.
Footnotes and Disclosure
The authors have no proprietary or commercial interest in any materials discussed in this article.
Prevalence of open-angle glaucoma among adults in the United States.