Long-term results of viscocanalostomy in pseudoexfoliative and primary open angle glaucoma

To document the outcome of viscocanalostomy (VC) alone or combined with phacoemulsification (phaco-VC) in eyes with pseudoexfoliation glaucoma (PEXG) and primary open angle glaucoma (POAG).

A prospective, comparative study of 314 eyes undergoing VC in two centres over 6 years was conducted. Main outcome measures were: (i) intraocular pressure (IOP) control (complete success was IOP < or = 18 mmHg without medication and failure IOP > 18 mmHg); and (ii) requirement for Nd:YAG laser goniopuncture (YAG-GP) if IOP > 21 mmHg.

In the POAG group, 174 eyes underwent phaco-VC and 104 VC. In the PEX group, 20 eyes underwent phaco-VC and 16 VC. At final follow up, complete success rate (CSR) was 76% for POAG phaco-VC, 67% for POAG VC, 95% for PEXG phaco-VC and 63% for PEXG VC with mean IOP reduction of 29.9%, 40%, 42.5% and 51%, respectively. Without YAG-GP, by 3 years postoperatively the failure rate was 100% for PEXG eyes and 21% for POAG eyes undergoing VC alone, but PEXG eyes undergoing phaco-VC were 100% successful. CSR for YAG-GP was 92% in PEXG VC eyes and 55% in POAG VC eyes.

In phakic eyes with PEXG undergoing VC, an absolute requirement for long-term success was YAG-GP. This was not the case in POAG eyes or PEXG eyes undergoing phaco-VC. Late IOP rise in phakic PEXG eyes and restoration of IOP control following YAG-GP suggests that continued release of PEX material from the lens capsule with time blocks the outflow through the trabecular-Descemetic window created by VC.