Predictors of long-term intraocular pressure control after lens extraction in primary angle closure glaucoma: results from the EAGLE trial

Background/aims
To assess baseline ocular parameters in the prediction of long-term intraocular pressure (IOP) control after clear lens extraction (CLE) or laser peripheral iridotomy (LPI) in patients with primary angle closure (PAC) disease using data from the Effectiveness of Early Lens Extraction for the treatment of primary angle-closure glaucoma (EAGLE) tria.

Methods
This study is a secondary analysis of EAGLE data where we define the primary outcome of ‘good responders’ as those with IOP<21 mm Hg without requiring additional surgery and ‘optimal responders’ as those who in addition were medication free, at 36-month follow-up. Primary analysis was conducted using a multivariate logistic regression model to assess how randomised interventions and ocular parameters predict treatment response.

Results
A total of 369 patients (182 in CLE arm and 187 in LPI arm) completed the 36-month follow-up examination. After CLE, 90% met our predefined ‘good response’ criterion compared with 67% in the LPI arm, and 66% met ‘optimal response’ criterion compared with 18% in the LPI arm, with significantly longer drops/surgery-free survival time (p<0.05 for all). Patients randomised to CLE (OR=10.1 (6.1 to 16.8)), Chinese (OR=2.3 (1.3 to 3.9)), and those who had not previously used glaucoma drops (OR=2.8 (1.6 to 4.8)) were more likely to maintain long-term optimal IOP response over 36 months.

Conclusion
Patients with primary angle closure glaucoma/PAC are 10 times more likely to maintain drop-free good IOP control with initial CLE surgery than LPI. Non-Chinese ethnicity, higher baseline IOP and using glaucoma drops prior to randomisation are predictors of worse long-term IOP response.