Abstract
Purpose :
The cornea possesses a natural structural anisotropy with respect to its superior-inferior and nasal-temporal direction, which is not maintained while grafting the donor cornea into the host eye. We hypothesize that structural misalignment between the host and donor cornea plays a crucial role in inducing topographical errors, which the surgeon is unaware of.
Methods :
Five 16 mm Corneoscleral buttons of central corneal thickness (< 0.6 microns) were imaged in an in-house developed polarimeter to acquire birefringence data. These buttons were then trephined using 7-8 mm stainless steel trephines. Subsequently, the trephined button was sutured to its parent button using 16 interrupted sutures using 10-0 nylon sutures. Before suturing, using, Gimble/Mendez ring, the trephined buttons were rotated by 0, 30, 45, 60, and 90 degrees to create a structural misalignment. The birefringence data was again collected for all the PK corneas after suturing and statistical analysis was performed on the acquired data.
Results :
We found that suture tension significantly (p<0.05) increases the birefringence, locally around the suture bites. However, structural misalignment has no significant influence on the increased birefringence due to sutures. Interestingly, the structural misalignment and suture tension collectively affect the suture-tissue interaction to create topographic irregularities, as characterized by varying behavior of isotropic points (IPs) in corneas with different misalignments.
Conclusions :
Not only suture tension but the structural matching of the host and the donor tissue is essential in mitigating the topographical irregularities in the cornea during PK. We propose that incorporating an additional step of aligning the host and the donor cornea in a typical surgical process may improve the refractive outcome of PK.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.