Intrastromal Implantation Of Ring And Corneal Graft Construct For Treatment Of Advanced Keratoconus.

To evaluate the safety and efficacy of a new combined ring and graft construct for treatment of advanced keratoconus. 

An interventional prospective case series in Vision Health Research Center, Semnan university of medical sciences, Semnan , Iran

A novel full circle PMMA ring with 12 holes was designed and synthesized.  A  lenticule with 200 µm thickness was obtained from donor cornea by femtosecond laser and sutured into the ring via its holes. Six patients suffered from advanced keratoconus were enrolled in the study. An intrastromal pocket was created by femtosecond laser at the 270 µm depth of cornea and the ring-graft construct was implanted.  Patients were followed at the first day, one week, one, three and 6 months after surgery .Post–operative UCVA, BCVA, corneal keratometry, thickness and biomechanics, low and high order aberrations, keratocyte and endothelial cell density were recorded and compered with pre-operative scales.

There is no any significant complication and vision loss was not recorded in these patients.  The mean corneal thickness was improved from 433 µm (range: 387- 458) to 578 (range: 544-598). Postoperatively, there was an improvement in manifest sphere and cylinder (P < 0.05 ). Preoperative Kmean was 48.7D, which significantly reduced and reached to 46.1D at last visit. Post-operative corneal biomechanics parameters significantly improved rather than pre-operative conditions.

The ring acts as an artificial limbus and support the graft in a tight position. The combination of ring and graft induced corneal flattening and improved corneal biomechanics. This construct is safe and effective for treatment of advanced keratoconus.