Consider zonules before cataract surgery
Assessing the zonules in angle closure
Paul Harasymowcyz MD
Surgeons can expect to find higher rates of zonulopathy in patients with various forms of angle closure pathologies and should plan lens extraction surgery with this possibility in mind, according to Paul Harasymowcyz MD.
“We looked at this in a recent study and found that the rates of zonulopathy in primary angle-closure suspect (PACS), primary angle closure (PAC) and primary angle-closure glaucoma (PACG) patients undergoing lens extraction was significantly higher than reported in the general population. Secondary pigment dispersion is also associated with a higher rate of zonulopathy. Ophthalmologists should be aware of the risks and be prepared to manage the zonulopathy intraoperatively,” he said at the World Ophthalmology Congress 2020 Virtual.
Dr Harasymowcyz, University of Montreal, Canada, noted that incidence of zonulopathy in the general population is approximately 0.50%.
“Our hypothesis was that because angle closure glaucoma is in part caused by weak or loose or absent zonules that the rate of vitreous loss or zonulopathy would be much higher in the PACS, PAC or PACG population. A secondary hypothesis was that the rate of secondary pigment dispersion and rubbing of the lens and iris pigment epithelium would also be more frequent in this population,” he said.
Dr Harasymowcyz’s retrospective cohort study included 1,013 consecutive eyes that underwent lens extraction by a single surgeon (PACS 266, PAC 366, PACG 381). The primary outcome was the rate of intraoperative zonulopathy as indicated by floppy capsule, phacodenesis, capsular tension ring use, anterior vitrectomy, or lens particles in the anterior vitreous. Secondary outcome was the presence of secondary pigment dispersion. Patients with a history of trauma, exfoliation syndrome or hereditary diseases were excluded.
“We found a 3.5% incidence of zonulopathy versus 0.5% in the general population. Three-quarters of patients (75%) required CTRs and the rate of secondary pigment dispersion was 15.3%. We feel that it is probably underestimated as a cause of angle closure glaucoma. Ophthalmologists should be aware of the intraoperative risks of cataract surgery in patients with angle closure, discuss this with their patients prior to surgery and prepare accordingly,” he said.
In the future, ophthalmologists will be able to draw on advances in imaging technologies such as ultrasound biomicroscopy (UBM) in order to better assess the condition of the zonules prior to surgery in patients with angle closure.
“There is definitely an unmet need for direct imaging of the zonules as many of the signs we currently use to detect zonulopathy are indirect ones. With UBM, we can show the presence or absence of zonules, but we need improved modalities in the future to determine the length and strength of the zonules,” he concluded.