Postoperative microhyphema as a positive prognostic indicator in canaloplasty

To assess risk factors for failure in canaloplasty.

Nonrandomized prospective study involving 51 eyes of 51 patients with medically uncontrolled primary open-angle glaucoma undergoing canaloplasty. Visual acuity, intraocular pressure (IOP) and slit-lamp examinations were performed before and after surgery at 1 and 7 days, and at 1 month and every 3 months thereafter. Factors like age, gender, preoperative IOP and microhyphema on day 1 were evaluated.

The mean follow-up was 20.6 (SD 8.3) months. The mean preoperative IOP was 26.8 (SD 5.2) mmHg; the mean postoperative IOP was 8.4 (4.2) mmHg at day 1 and 12.7 (1.7) mmHg at month 24. Microhyphema was found in 40 patients (85.1%) on day 1 after surgery. The height of microhyphema was 1.8 mm ± 0.4 (SD) (range 1-2.5), and the time of resorption was 6.6 days ± 2.8 (SD) (range 3-14) on average. No recurrence of hyphema has been observed. IOP < 16 mmHg without medications depended significantly on the presence of microhyphema (hazard ratios, HR 0.03, 95% CI 0.01-0.25, p < 0.001), but not on age (HR 1.00, 95% CI 0.91-1.09, p = 0.32), preoperative IOP (HR 0.98, 95% CI 0.85-1.12, p = 0.80), cup-to-disc ratio (HR 0.15, 95% CI 0.00-20.01, p = 0.45) and gender (HR 0.24, 95% CI 0.05-1.12, p = 0.07). Factors like preoperative IOP, age, gender, cup-to-disc ratio were not associated with microhyphema. There were no significant differences between patients with versus without microhyphema in regard to age, preoperative IOP, morphological and functional glaucomatous damage, number of medications and postoperative day 1 IOP. However, patients with microhyphema had significantly fewer Nd:YAG goniopunctures after surgery than patients without microhyphema (p < 0.001).

Microhyphema the first postoperative day seems to be a significant positive prognostic indicator in uneventful canaloplasty in regard to IOP reduction, possibly representing a restored and patent physiologic aqueous outflow system.