PURPOSE: To evaluate associations between preoperative diagnosis, soft contact lens (SCL) retention and complications. METHODS: A retrospective chart review was conducted of 92 adult patients (103 eyes) who received a Boston keratoprosthesis type I at the Massachusetts's Eye and Ear Infirmary or the Flaum Eye Institute. Records were reviewed for preoperative diagnosis, SCL retention and subsequent complications. Preoperative categories included 16 autoimmune (Stevens-Johnson syndrome, ocular cicatricial pemphigoid, rheumatoid arthritis and uveitis), 9 chemical injury and 67 'other' (aniridia, postoperative infection, dystrophies, keratopathies) patients. RESULTS: 50% of the lenses had been lost the first time after about a year. A subset (n=17) experienced more than 2 SCL losses per year; this group is comprised of 1 patient with autoimmune diseases, 2 patients with chemical injuries and 14 patients with 'other' diseases. The preoperative diagnosis was not predictive of contact lens retention. However, multivariate analysis demonstrated that the absence of a contact lens was an independent risk factor for postoperative complications, such as corneal melts with or without aqueous humour leak/extrusion and infections. CONCLUSIONS: Presence of a contact lens after Boston keratoprosthesis implantation decreases the risk of postoperative complications; this has been clinically experienced by ophthalmologists, but never before has the benefit of contact lens use in this patient population been statistically documented.