Intraocular pressure should be checked in fellow eyes following glaucoma surgery

This prospective study was conducted to evaluate the progression and magnitude of change in intraocular pressure (IOP) in patients undergoing procedures for glaucoma.

Study design

A total of 131 patients with glaucoma undergoing trabeculectomy, combined cataract surgery and trabeculectomy, or Ahmed valve placement for any glaucoma diagnosis were included in the study. Oral carbonic anhydrase inhibitors and all topical antihypertensives were discontinued in the operative eye. Regular follow-up visits occurred for 6 months following surgery. Separate investigations were conducted in patients who had been taking oral acetazolamide preoperatively. An IOP change in the fellow eye of >4 mm Hg or a >20% IOP increase from baseline was considered clinically significant.

Outcomes

The mean baseline IOP of fellow eyes was 13.1 ± 3.3 mm Hg, which increased to a maximum of 16.3 ± 3.7 mm Hg at postoperative week 1. A significant positive correlation was observed between IOP reductions in the operated eye and IOP increases in the fellow eye. Higher IOP elevation in fellow eyes was linked to previous glaucoma surgery, a diagnosis of glaucoma from cataract surgery, Ahmed valve implantation in the index eye, early postoperative hypotony in the index eye, and preoperative use of acetazolamide. After 1 week, patients taking acetazolamide saw an IOP increase in fellow eyes of 5.0 ± 2.4 mm Hg, compared with an IOP increase 1.8 ± 3.0 mm Hg in patients not taking acetazolamide.

Limitations

A significant number of patients were taking oral acetazolamide preoperatively, which was discontinued at the time of surgery. Acetazolamide withdrawal likely played a large role in the IOP rise in those fellow eyes; excluding these patients may have allowed for better characterization of the consensual ophthalmic response. Similarly, but to a lesser extent, crossover effect and then withdrawal from preoperative topical antihypertensives in the index eye may have accounted for some of the postoperative IOP rise in the fellow eyes.

Clinical significance

While this study does not elucidate the exact mechanism of the consensual ocular response, it does provide a good real-life example of IOP consequences in fellow eyes following glaucoma surgery. This study serves as a reminder to always thoroughly examine both eyes during the postoperative period. The waning IOP rise 1 week postoperatively may reassure glaucoma surgeons that they can watch and wait out IOP rise in the fellow eye without rushing to surgical intervention.