Abstract
Purpose :
Myopia is rapidly becoming a leading cause of permanent blindness worldwide. Available clinical data shows that short radial corneal incisions (Mini/Micro RKs) are effective in inducing keratometric changes as a means to correct myopia. The purpose of this study is to present the minimally-invasive radial keratotomy generated by the femtosecond laser system (LENSAR Inc), then, the analysis of the incision depth and consistency achieved. Qualitative evaluation of the incision is also discussed.
Methods :
Minimally invasive radial keratotomy or Mini/Micro-RK consists of up to 4 radial incisions. The incisions are short, approximately 2-3mm, extending from the 4.0mm to about 8.0 or 9.0mm of the central clear corneal zone.
The incisions were generated with particular attention to the irregularity of the cornea thickness along the radial and circumferential direction in order to maintain a constant incisional depth, percent corneal thickness or residual uncut bed thickness over the course of the laser cutting process. After the laser treatment, an anterior segment optical coherence tomography (OCT) system was used to measure the accuracy and regularity of corneal incisions.
Results :
Five (5) porcine eyes were utilized per depth subset investigated. Four (4) micro/mini-RKs were generated on each eye. The results showed that for the first and second subsets with the intended incision depths of 50% and 80% of the corneal thickness, the mean depths achieved were 50.01% and 77.69% thickness, respectively. The incision depths ranged from 47.10% to 53.25% and 74.17% to 81.55% for the first subset (50% thickness depth target) and the second subset (80% thickness depth target), respectively. The computed mean absolute errors for the incision depths achieved with this cohort were 12.66 μm and 23.33 μm, for the first and second subsets, respectively. The same porcine eyes were also utilized to evaluate the incision quality. The incisions were generally easy to open and the interfaces were smooth.
Conclusions :
Femtosecond laser Mini/Micro-RK can be an effective means to help meet the refractive outcome expectation after cataract surgery or for myopic patients. The use of a femtosecond Laser System to effect a corneal power change is safe and makes the procedure faster and easier for surgeons and more comfortable for the patients.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.