Long term effect of trabeculectomy on retrobulbar haemodynamics in glaucoma

Previous reports showed increased flow velocities in retrobulbar vessels after glaucoma surgery in the first weeks. Colour Doppler imaging was performed to investigate the long-term effects of trabeculectomy on retrobulbar haemodynamics in patients with primary open-angle glaucoma (POAG).

In a prospective study 30 patients (mean age 63.2 ± 15.4 years) with POAG were included. Colour Doppler imaging was performed before 1-2 weeks, after 2 months, after 4-6 months, and up to 3 years after trabeculectomy to determine the peak systolic and end-diastolic velocities in the ophthalmic artery, central retinal artery, and the short nasal and temporal posterior ciliary arteries.

Mean follow-up was 416 ± 246 days. In the first postsurgical period mean intraocular pressure (IOP) decreased after trabeculectomy from 25 ± 6 mmHg to 9 ± 4 mm Hg (p < 0.0001) and then increased in the further follow-up to 13 ± 3 mmHg (p < 0.05) without any anti-glaucomatous medication. Colour Doppler imaging revealed a significant increase of the end-diastolic velocities of the central retinal artery at all postoperative visits compared to pre-surgery (p < 0.003) and of the end-diastolic velocities in the temporal posterior ciliary arteries (p < 0.003). The change of blood flow parameters that increased during follow-up was significantly correlated to the change in ocular perfusion pressure and IOP.

End-diastolic velocities of the central retinal artery and of the temporal posterior ciliary arteries increased after successful trabeculectomy and remained stable in a longer period - even if IOP rose significantly in the follow-up.