Purpose:
To observe configuration of graft-host (GH) apposition after penetrating keratoplasty (PKP) for keratoconus using anterior segment OCT (AS-OCT).
Methods:
Retrospective case series study. 23 patients (24 eyes) with keratoconus after PKP were involved in this study, and all of them had removed sutures. The examinations included slit-lamp microscopy, manifest refraction, corneal topography and AS-OCT. The mode of "high resolution corneal 4-lines at 45°apart " was selected in AS-OCT exam, so that eight optical sections of GH junction on 4 axes were acquired from each eye. Classification of GH malappositions and their severity were determined, and size of GH touch was measured.
Results:
Although all of 192 GH sections from 24 eyes had continuous smooth epithelial surface, 138 sections of them had internal GH malapposition including "Graft Step" (52), "Host Step" (28), "Hill Protrusion" (34), "Tag Protrusion" (11), and "Gape" (13). Internal Step and Gape significantly reduced GH touch, while Hill Protrusion significantly increased GH touch. LogMAR best corrected visual acuity (BCVA) (rs = 0.5421, P = 0.0062), Corneal astigmatism (rs = 0.7816, P = 0.0000) and corneal irregularity measure (CIM) (rs = 0.5596, P=0.0045) were all significantly correlated with severity of GH malapposition. Moreover, spherical equivalent (rs = 0.5271, P = 0.0081) and semi-meridian keratometry on the same direction (rs = -0.4358, P = 0.0000) were both significantly correlated with size of GH touch.
Conclusions:
Our study with AS-OCT found internal GH malappositions were common after PKP in patients with keratoconus, and internal malappositions were closely associated with postoperational irregular astigmatism that limited improvement in visual function. Therefore, more attention should be paid to internal GH apposition in PKP.
Keywords: cornea: clinical science • wound healing • transplantation