Abstract
Purpose: :
To report our novel technique of argon laser iridoplasty (ALI) for treatment of visually significant optic obstruction after Boston keratoprosthesis (KPro).
Methods: :
A retrospective study was conducted of patients with Boston KPro who developed visually significant optic obstruction and underwent ALI for treatment. The medical records were reviewed to assess pre and post-procedure best-corrected visual acuity (BCVA), laser technique and complications. Anterior segment optical coherence tomography (AS-OCT) pre and post-laser were also examined.
Results: :
Two patients with implanted Boston KPro type 1 were included in the study. The first patient, a 74 year-old male with chemical burn and glaucoma had primary KPro and iris sphincterotomies. The second patient, a 66 year-old female with multiple failed corneal grafts and glaucoma, underwent KPro and pars plana shunt placement. Iris was first observed at the optic margin 3 months postoperatively for both patients but did not cause visual obstruction. For patient 1, progressive central migration of the iris obstructed the optic by 1.3 mm, with decline in BCVA to 20/100 by postoperative year 2. Similarly, patient 2 had 0.98 mm iris obstruction by postoperative year 4.5, with decline in BCVA to 20/800 and worsening of her visual field. For both patients, AS-OCT showed mobile iris obstructing the visual axis and continued glaucoma and retinal evaluation became limited.The patients underwent ALI with settings to produce contraction burns, with low power (200-400mW), long duration (1.0 second) and large spot size (500 μm). The aiming beam was directed just peripheral to the optic in the area of obstruction to cause optimal contraction of iris stroma away from the optical window. Post-laser, patient 1 had iris retraction by 1.01 mm and improvement of BCVA to 20/70. The second patient had only 0.52 mm of iris remaining at the optic margin and improvement of both BCVA to 20/80 and peripheral field by Humphrey visual field testing. AS-OCT showed clearance of the visual axis and no complications were noted and intraocular pressure remained stable.
Conclusions: :
We present our novel technique of ALI as a safe, effective and relatively simple outpatient procedure and as a less invasive alternative to surgical intervention for treatment of visually significant optic obstruction after KPro.
Keywords: keratoprostheses • laser • imaging/image analysis: clinical