Microscope Integrated Optical Coherence Tomography Assisted Graft Sizing In Pediatric Penetrating Keratoplasty

To describe the use of Microscope Integrated Optical Coherence Tomography (MIOCT) as an additional tool in assessing anterior chamber and modifying graft size and thus graft host disparity in pediatric penetrating keratoplasty.

This is a prospective Interventional Study done in a tertiary eye care center in India in 45 eyes of pediatric patients <16 years of age. All patients with indications of penetrating keratoplasty were included in our study, after excluding posterior segment pathologies. Infective keratitis with indications of therapeutic penetrating keratoplasty was excluded from our study.

All patients underwent examination under anesthesia, in which corneal diameters were assessed and a host trephine size sparing at least 2mm from the limbus was used. The anterior chamber assessment was done using MIOCT, and the anterior chamber angle, peripheral synechiae, and lens status were assessed before the surgery as well as intraoperatively after lamellar dissection. The host sizing was done as per anterior segment anatomy, with a disparity of 1.00-1.25mm if the angle was crowded and peripherally shallow with the presence of synechiae. If additional lens removal was anticipated and done, the graft host disparity was kept to 1mm. In cases with normal anterior segment, aphakia, or aniridia, a 0.75 graft host disparity was taken.

The average horizontal and vertical corneal diameters were 11.3±1.60 and 11.03±1.17 respectively. In 86.6% of eyes, the pupil and lens details were completely obscured clinically, 62.2% had iridocorneal adhesions, 15.5% aniridia, and 66.6% had a shallow peripheral anterior chamber as seen on MIOCT. The average host trephination, donor trephination, and graft-host disparity were 7.10±0.62mm, 7.96±0.54mm, and 0.86±0.24mm respectively. Additional procedures such as synechiolysis, pupilloplasty, and lens extraction were done in 46.6%, 8.8%, and 8.8% of eyes respectively. The average postoperative astigmatism was found to be 6.5±3.23D at 1 year postoperatively. The overall graft survival rate at 1 year was found to be 60%. 

Through our study, we describe another utilization of MIOCT in decision-making in a crucial step of deciding the graft sizing and graft-host disparity in cases of pediatric penetrating keratoplasties, which are difficult to assess and plan preoperatively. A graft-host disparity of 1.00-1.25mm can be advocated in cases with shallow angles, peripheral synechiae, and flatter cornea, and a lesser graft-host disparity of 0.75mm in cases with additional lens extraction procedures, aniridia, and aphakia to obtain a better postoperative corneal curvature. Thus, the decision-making in graft sizing and graft-host disparity can be enhanced after the assessment of the anterior segment anatomy using MIOCT.