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

Purpose: 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). Methods: 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 ≤ 18 mmHg without medication and failure IOP > 18 mmHg); and (ii) requirement for Nd:YAG laser goniopuncture (YAG‐GP) if IOP > 21 mmHg. Results: 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. Conclusions: 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.