Cataract surgery

Growing evidence suggests that cataract surgery alone is sufficient to control closed-angle glaucoma in many patients. However, for open-angle cases, cataract surgery often does not lower intraocular pressure (IOP) enough to make it a viable stand-alone surgical treatment, Norman A Zabriskie MD of the Moran Eye Centre, University of Utah, told the ASCRS Glaucoma Day 2015 in San Diego, USA.

The strongest evidence for cataract surgery alone as a primary surgical treatment for closed-angle glaucoma comes from three randomised controlled studies conducted by Clement CY Tham FRCS and colleagues in Hong Kong, said Dr Zabriskie. They compared phacoemulsification alone with laser peripheral iridotomy for medically aborted acute primary angle-closure glaucoma; and compared phaco alone with phaco plus trabeculectomy in patients with medically-controlled and uncontrolled chronic closed-angle disease.

Acute angle-closure patients receiving early phaco had less late IOP rise, lower mean IOP, higher Shaffer angle grading, and required fewer medications to control IOP than those receiving iridotomy (Ophthalmology. 2008 Jul;115(7):1134-40).

For medically-controlled and uncontrolled chronic closed-angle glaucoma, phaco alone produced similar or slightly higher IOP and required about one more medication to control IOP, but had fewer complications and no difference in disease progression than phacotrabeculectomy (Ophthalmology. 2008 Dec;115(12):2167-2173; Ophthalmology. 2009 Apr;116(4):725-31).

“There is compelling evidence from randomised clinical trials to support cataract surgery alone as an important treatment modality in patients with acute and chronic angle-closure glaucoma,” Dr Zabriskie said. Phaco alone is especially useful in cases with early to moderate disease, he added.

Open angle, open question

The evidence for phaco alone in managing open-angle glaucoma is less clear, Dr Zabriskie said. One early retrospective study showed phaco’s IOP-lowering effect increased with higher preoperative pressures, reaching 35 per cent IOP reduction in patients with 23 to 29mmHg pre-op IOP, but the studies’ failure to confirm angle status pre-op raises doubts (Poley et al. J Cataract Refract Surg. 2009 Nov;35(11):1946-55).

Other studies, including patients who had cataract surgery in the control arm of the Ocular Hypertension Treatment Study, show IOP decreases in the 2.0 to 4.0mmHg range.

So cataract surgery alone is not a solution in cases of open-angle glaucoma needing IOP-lowering of 20 per cent or more, Dr Zabriskie said. In these cases he usually considers adding a pressure-lowering procedure. However, phaco alone may be useful for open-angle glaucoma patients with well-controlled IOP requesting cataract surgery, and in patients in whom a modest reduction in IOP is desirable.

Norman A Zabriskie: norm.zabriskie@hsc.utah.edu