Primary angle-closure glaucoma (PACG) is a distinct condition from primary open-angle glaucoma (POAG), and treating patients who are merely at risk for it requires a whole new handbook. A new study is showing that these two types of glaucoma have at least one extreme distinction. In POAG, cataract surgery can lower intraocular pressure (IOP) and help mitigate damage from the disease.1 However, for PACG, despite IOP control, a substantial number of PACG patients continue to experience glaucomatous progression.2 “This result may suggest that lens extraction should be performed early to prevent PACG,” the researchers said.2
The investigators performed a retrospective observational study of 77 eyes that underwent lens extraction and were followed for more than two years after the procedure. The subjects were divided into three groups: primary angle-closure suspects (PACS, 17 patients), primary angle-closure (PAC, 24) and PACG (36). They analyzed patients’ IOP mean, peak and fluctuation both before and after lens extraction. They also evaluated the subjects’ visual fields (VF), mean deviation (MD) immediately after lens extraction and at their final follow-up appointment. Postoperative glaucoma progression was determined by three criteria: optic disc/retinal nerve fiber layer (RNFL) photographs, OCT and VF.2
They discovered that while the surgery significantly reduced mean and peak IOP and IOP fluctuation in all groups, postoperative VF MD was significantly aggravated in the PACG group. It changed from −7.26dB pre-op to −8.82dB after surgery. VF conversion was not seen in PACS or PAC eyes.2
“In general, glaucomatous progression occurs in both structural and functional aspects, which may not develop at the same time,” the researchers explained. “Our result may suggest that despite the adequate control of IOP after a successful lens extraction, PACG eyes can still experience glaucomatous progression.”2
1. Berdahl J. Cataract surgery to lower intraocular pressure. Middle East Afr J Ophthalmol. 2009;16(3):119–22.
2. Song M, Sung K, Shin J, et al. Glaucomatous progression after lens extraction in primary angle closure disease spectrum. J Glaucoma. May 1, 2020. [Epub ahead of print].