Implantation of 320°-Arc Length Intrastromal Corneal Ring Segments in Keratoconus, A prospective study

Background: Keratoconus (KC) is a gradual thinning of the cornea with an unclear cause. Myopia and increasing irregular astigmatism are the main causes of the decline in visual acuity. The management of corneal corneal ring segments (ICRS) has undergone significant modification. An efficient long arc ring is the 320-ICRS.Aim of the study: To assess the clinical results following the implantation of a 320°-ICRS in KC patients' eyes.Patients and methods: Twenty male and twenty female patients, ages ranging from 14 to 46 years, with an average age of 27.48±7.76 years, whose 60 eyes were included in this prospective, nonrandomized, interventional trial. Following a comprehensive ophthalmological examination and the results of the Pentacam corneal tomography, KC was identified in all of the patients. The classification of cases was done using the Amsler-Krumeich grading system. Following the creation of the stromal tunnel and incision with femtosecond technology, a circular array of 320 ICRSs was implanted.Results: The mean preoperative best-corrected distance visual acuity (BCVA) was 0.30±0.13 decimal, which changed to 0.51±0.12 decimal six months after operation (p<0.001). The spherical equivalent shows a significant reduction postoperative in comparison to preoperative. The mean postoperative K1, K2, and Kmax show a significant reduction in comparison to preoperative (p<0.001). This study found no significant difference between grade 2 and 3 Amsler classifications when we implant 320 ICRS.Conclusion: Implanting a 320-degree ICRS is a safe and effective procedure and improve visual acuity for treating patients with KC, modifying the corneal shape to a more physiologic, aspheric shape.