Incidence and Risk Factors for Poor Postoperative Visual Outcome After Excision of Orbital Cavernous Venous Malformations.

AIMS: To determine the incidence and risk factors for poor postoperative visual outcome (PPVO) after removal of orbital cavernous venous malformations (OCVMs).

METHODS: Retrospective case-note and imaging review for patients undergoing excision of OCVMs, with estimation of odds-ratios (ORs) and relative risks (RRs) for visual loss in relation to the position of the mass, surgical approach, and patient factors.

RESULTS: The 290 patients (179 female; 62%) presented at a mean age of 46.4 years: 243/287 (85%) OCVMs were intraconal, with 213/243 (88%) located freely in the posterior two-thirds of the orbit, and 30/243 (12%) wedged tightly in the apex. PPVO was observed in 6.9% (20/290) patients, solely after removal of intraconal lesions, Univariate analysis showed increased risk with preoperative relative afferent pupillary defect (RAPD) (14/107 [13%]; RR 2.9; P = 0.011), apical lesions (9/30 [30%]; RR 5.8; P < 0.001), situated below optic nerve (15/115 [13%]; RR 3.3; P = 0.007), fibrous masses (14/78 [18%]; RR 6.7; P = 0.005), or intraoperative diastolic blood pressure below 50mmHg (10/64 [16%]; RR 2.8; P = 0.007). Multivariate analysis found apical extension (OR 4.9; P = 0.036) and fibrous lesions (OR 10.0; P = 0.035) as strongest predictors for PPVO. The incidence of complete visual loss (no light perception) was 4.1% (12/290); half of these patients had preoperative acuity of counting fingers or worse, 8 (67%) had RAPD, 7 (58%) wedged apical lesions, and 8 (67%) were below the optic nerve.

CONCLUSION: PPVO after excision of OCVMs can occur in up to 5% of "free" retrobulbar intraconal lesions and in approximately one-third of apical lesions.