Topography-Guided PRK After Intrastromal Corneal Ring Segment Implantation Followed by CXL in Keratoconus Patients
Narrative Responses:
Purpose
To evaluate the efficacy of topography-guided photorefractive keratectomy (PRK) after intrastromal corneal ring segment (ICRS) implantation followed by collagen crosslinking (CXL) in the management of keratoconus.
Methods
Prospective, non-comparative analysis of case series comprised 23 eyes of 20 patients who had keratoconus stabilized by ICRS implantation and collagen crosslinking. Standard CXL procedure was performed 3-5 months after ICRS implantation. At least 3 months of stable refraction and pachymetry after CXL procedure preceded to PRK. All eyes had corneal thickness more than 450mm and ablation depth up to 50mm. Surface ablation was performed using MicroScan Visum excimer laser (Optosystems). The outcome measurements included UDVA, CDVA, mean and steep K values, posterior cornea surface elevation data. Postoperative assessments were performed 1, 3, 6 and 12 months.
Results
Six months after topography-guided PRK there was a significant improvement in UDVA from 0.09±0.04 (range 0.05–0.2) to 0.47±0.16 (range 0.16–0.8) and CDVA from 0.45±0.18 (range 0.16–0.7 ) to 0.64±0.13 (от 0.16-0.9). 56.5% of eyes had UDVA 20/40 or better. Mean refraction spherical equivalent decreased from -6.51±1.41D to -1.70±0.35D to –3.8±0.49D. Mean subjective cylinder correction decreased from 4.32±2.11D to 1.78±0.94D. Steep K value decreased from 54.13D to 45.38D No eyes lost lines of CDVA. There was no significant change in maximum posterior cornea elevation value.
Conclusion
Topography-guided PRK after ICRS implantation and collagen crosslinking is effective for improving visual acuity in select patients. A larger study is needed to determine the long-term impact of this method for ametropia correction on the progression of keratoconus.