The best thickness of cornea graft from SMILE surgery as patch graft in glaucoma drainage implant surgery

Abstract

Objective:The aim of this study was to determine the best thickness of corneal slices acquired from femtosecond laser surgery - small incision lenticule extraction (SMILE surgery) as patch graft in glaucoma drainage implantation surgery.Methods:This study is a prospective randomized study. Patients who received glaucoma drainage implantation from September 2016 to November 2018 were observed. The patients were randomly divided into 3 groups. Group A included 102 cases (104 eyes), receiving 1 layer (120-150μm) of allogeneic lamellar corneal tissue as the graft. Group B included 117 cases (120 eyes), receiving 2 layers of lamellar corneal tissue from one donor. Group C included 109 cases (111 eyes), using 3 layers of lamellar corneal tissue from 2 donors. The intraocular pressure, corneal graft, conjunctiva stromalysis, drainage tube exposure, and drainage plate were observed.Results:Patients were followed up for 6 to 33months. The intraocular pressure was significantly reduced after surgery in all three groups. Conjunctiva stromalysis and drainage tubes were exposed in 3 eyes (3%) in group A and 1 eye (0.8%, a special case which has nystagmus and the plate was placed infratemporally) in group B, whereas no conjunctiva stromalysis or tube exposure was reported in group C.Conclusions:The corneal graft acquired from SMILE surgery can effectively prevent drainage tube exposure and give patients a better cosmetic appearance. Two layers of lamellar corneal tissue (240-300μm) may be the best suitable thickness because it can effectively reduce tube exposure and rejection. In some special cases, 3 layers of lamellar corneal tissue are needed.