Assessment of Glaucomatous Damage After Boston Keratoprosthesis Implantation Based on Digital Planimetric Quantification of Visual Fields and Optic Nerve Head Imaging

Purpose: To investigate glaucomatous damage in Boston keratoprosthesis type I (KPro) patients through structural analysis of the optic nerve head and digital planimetric quantification of Goldmann visual fields, a novel method of monitoring perimetric changes in KPro patients. Methods: Records of patients undergoing KPro implantation from 2007 to 2015 at a single institution were reviewed. Parameters related to glaucoma status and KPro outcomes were analyzed. Results: Twenty-two eyes from 21 patients met inclusion criteria, with mean follow-up of 49.4 months (range 15-90). Mean results for the following parameters before KPro implantation and at last follow-up were (pre-KPro; at last follow-up): best-corrected visual acuity (2.07; 0.70 logMAR), number of glaucoma medications (1.14; 1.05), intraocular pressure (IOP) (18.4; 18.4 mm Hg), vertical cupto-disc ratio (C/D) (0.48; 0.50), and horizontal C/D (0.52; 0.52). IOP-lowering procedures were performed pre-KPro (5/22), concurrently with KPro (10/22), post-KPro (6/22), or never (6/22). An increase in C/D >= 0.1 and loss of V4e isopter area >30% occurred in 22.7% and 12.5%, respectively. Development of post-KPro glaucoma, progression of preexisting or post-KPro glaucoma, and no glaucoma development as evidenced by an objective assessment of structural and functional parameters were seen in 2/22 (9.1%), 7/22 (31.8%), and 6/22 (27.3%) eyes, respectively. Conclusions: Clinicians should strive to vigilantly monitor for glaucoma despite the inherent difficulties in tonometry, optic nerve visualization and imaging, and visual field testing in KPro patients. Meticulous glaucoma surveillance with structural and functional testing combined with earlier IOP-lowering surgical intervention may result in decreased rates of glaucomatous vision loss in KPro patients.