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This multi-centre randomized controlled trial (RCT) investigated whether clear lens extraction was of more benefit than peripheral laser iridotomy (standard care) in terms of patient quality of life, intraocular pressure (IOP), and cost, in primary angle-closure patients with high IOP (> 30 mmHg) or those presenting with primary angle-closure glaucoma.
There was a clear need for this study given the lack of evidence in this area1 and the variable approach taken by clinicians with these patients,2 the default position usually being laser iridotomy. Several notable strengths of this study included the large sample size that included multiple ethnicities (31% Chinese) and data quality (409 participants were included in the intention- to-treat analysis at three years), and the pragmatic design of the study which allowed the glaucoma specialists freedom to follow their own medication, laser (e.g., argon laser peripheral iridoplasty) or surgical choices after the primary treatment if escalation of treatment was needed to achieve a target IOP (a range of 15-20 mmHg IOP set at baseline depending on the degree of optic neuropathy).
The clear-lens extraction group had significantly better quality of life scores (EQ-5D), visual function and intraocular pressure control, on fewer eye drops (mean, 0.4 medications; 61% required no further IOP treatment) than those who received a primary iridotomy (mean, 1.3 medications; 21% required no further IOP treatment) at three years. Clear-lens extraction was also more cost-effective when considering the UK sites where complete cost and quality-adjusted life-year (QALY) scores were available. Importantly, those undergoing primary iridotomy were much more likely to undergo further surgeries in the next three years, mainly cataract extraction but also trabeculectomy (six times more likely) which can be a more hazardous procedure in patients with angle closure.3 It was gratifying that the posterior capsule rupture rate was so low in the lens extraction group (1%) given that cataract surgery can be more technically challenging in these patients.
Complications of clear-lens extraction in these types of patient are probably more common outside of this study environment given that the investigators were glaucoma specialists who are generally very experienced cataract surgeons, yet effective risk stratification of the case to the skill level of surgeon should mitigate this.4
Importantly, these results cannot be extrapolated to those with primary angle closure with IOPs of less than 30 mmHg nor those with only occludable angles (primary angle closure suspects). However, several prospective cohort studies and RCTs involving patients with this lesser degree of glaucoma risk are contributing to a growing evidence base around efficacy and safety of interventions.5-7
Augusto Azuara Blanco et al. should be commended for this impressive well-designed landmark study which provides strong support for considering clear lens extraction as the first-line treatment for individuals with high-pressure primary angle-closure and primary angle-closure glaucoma.