Treating Angle Closure Glaucoma
Good preoperative IOP control without medication, Chinese nationality are predictors of good outcome for both lensectomy and iridotomy.
Published: Wednesday, June 30, 2021
Patients with primary angle-closure glaucoma (PACG) or primary angle closure and high intraocular pressure (IOP) are less likely to need medication or surgery if they start with cataract surgery than if they start with a peripheral laser iridotomy, said Prof David S Friedman MD, MPH, PhD, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA. “Other important predictors of good eye pressure control with either treatment included having a lower presenting eye pressure, not requiring eye drops initially to control the eye pressure, and being Chinese,” said Prof Friedman, who presented a review and analysis of the three-year results of the early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE) trial at the ARVO 2021 Congress. He noted that the EAGLE trial was a multicentre randomised controlled study comparing clear lens extraction (CLE) to laser peripheral iridotomy (LPI) in 419 patients who had newly diagnosed PAC or PACG and did not have cataract. The trial was conducted in Europe, Asia, and Australia, with most participants originating from the UK. The target IOP in the study was 15–20 mmHg and the need for an increase or decrease in IOP-lowering medications was determined by the physician. Those whose IOP was not adequately controlled by medication could be offered surgery. Their baseline characteristics were a mean age of 67 years, a diagnosis of PAC in 37% and of PACG in 62%, a mean baseline IOP of 28.9 mmHg and a mean deviation (MD) of -4.2 dB. In addition, 29% of patients were of Chinese ethnicity. BETTER IOP CONTROL WITH CLEAR LENS EXCHANGE Prof Friedman noted that at 36-month follow-up the mean IOP was lower among eyes in the CLE group, having decreased from a mean baseline of 29.5 mmHg to 16.6 mmHg, compared to a decrease from 30.3 mmHg to 17.9 mmHg in the LPI group. That was despite the fact that 66% in the CLE group were using no IOP-lowering medication throughout follow-up, compared to only 18% in the LPI group. In addition, only one study eye randomised to CLE underwent trabeculectomy, compared to six study eyes (2.8%) in the LPI arm. Furthermore, compared to the LPI group, patients in the CLE group reported a better quality of life in their responses to the EQ-5D questionnaire, which measures problems in five quality-of-life domains. Moreover, incremental cost analysis showed a benefit of ELE in terms of quality-adjusted life years (QALY), Prof Friedman said. WHICH PATIENTS DO BEST? Using data from the EAGLE trial, Prof Friedman and his associates conducted a study to assess the baseline parameters associated with better long-term IOP control. In their analysis, they defined “good responders” as those having an IOP lower than 21 mmHg at the 36-month follow up without any further surgery and they defined “great responders” as those who maintained an IOP lower than 21 mmHg after the same follow-up period without requiring medication or further surgery. Their analysis showed 89.6% of the patients in the CLE group had a good response compared to 66.8% of eyes in the LPI group. In addition, 63.9% in the CLE group were great responders, compared to only 17.7% in the LPI group. Furthermore, multivariate logistic regression analysis showed undergoing CLE rather than LPI was the strongest factor predicting a good response, with an odds ratio of 4.5, and was an even stronger predictor of a great response, with an odds ratio of 10.1. Another predictive factor for a good response were low baseline IOP, with an odds ratio of 1.2 for every 5 mmHg lower of IOP baseline. Predictors of a great response included Chinese nationality, with an odds ratio of 2.3, and not using glaucoma medications at baseline, with an odds ratio of 2.8. A diagnosis of PAC vs. PACG was also a predictor of a great response, with an odds ratio of 2.1, as was a good baseline visual field which increased the odds ratio for a great response by 1.06 for every for decibel better. Looking at the two treatments separately, the main predictor of a good response after LPI was lower IOP at baseline. LPI had the same predictive factors for a great response as the study group overall. In eyes that underwent CLE the odds ratio of a good response increased by 1.2 for every 1.0 mm of shallowness of the anterior chamber depth. The strongest predictor of a great response was not receiving glaucoma medications at baseline. “The take home messages is that after clear lens extraction, IOP was controlled in nearly 90% without further surgery at three years, and almost two-thirds required no medications. On the other hand, those already requiring medications, those with PACG, and those undergoing laser iridotomy are less likely to be free of medications long-term and are also more likely to require additional surgery,” Prof Friedman said. Prof David S Friedman MD, MPH, PhD: firstname.lastname@example.org