Preoperative, intraoperative, and postoperative assessment of corneal biomechanics in refractive surgery.

PURPOSE OF REVIEW: To review current and emerging methods and utilities of preoperative, intraoperative, and postoperative measurements of corneal biomechanics and their effects on refractive surgery decision-making. RECENT FINDINGS: Several recent clinical and preclinical studies have demonstrated the utility of corneal biomechanical analysis in refractive surgery. These studies focus on both screening surgical candidates for keratoconic disease as well as intraoperative and postoperative monitoring. The measurement of spatially resolved biomechanics is beginning to be studied in humans. SUMMARY: Clinically available screening methods combining corneal biomechanics with topographic and tomographic data provide increased utility when screening for keratoconic disorder. Spatially resolved measurement of corneal biomechanics holds great potential for preoperative, intraoperative, and postoperative evaluation of refractive surgery candidates as well as for more individualized procedures in the future.

Transepithelial Corneal Crosslinking Using a Novel Ultraviolet Light-Emitting Contact Lens Device: A Pilot Study.

Purpose: To evaluate the feasibility of a novel, on-eye UVA light-emitting contact lens device driven by fiber optics for the corneal crosslinking (CXL) of patients with keratoconus. Methods: In nine corneal transplant candidates with advanced keratoconus a scleral contact lens reservoir containing 0.007% benzalkonium chloride preserved with 0.25% riboflavin-monophosphate was placed on the eye for 30 minutes. The reservoir lens was removed and replaced with the CXLens UVA light-emitting contact lens. A 375-nm UVA light at 4 mW/cm2 intensity was delivered for 30 minutes for a dose of 7.2 J/cm2. A one-sided paired t-test was used to evaluate mean differences in maximum keratometry, thinnest corneal thickness, and endothelial cell density between screening and 6 months after CXL. A two-sided paired t-test was used to evaluate differences in best-corrected distance visual acuity between screening and 6 months after CXL. Results: All patients received the treatment as per protocol and adhered to follow-up testing. At 6 months after CXL, treated eyes had an average -1.0 ± 1.6 diopters decrease in the maximum keratometry (P = 0.049), a nonsignificant 2.3 ± 7.5 letter improvement in best-corrected distance visual acuity (P = 0.19), a nonsignificant -17 ± 14 µm decrease in thinnest corneal thickness (P < 0.01), and a nonsignificant -86 ± 266 cells/mm2 decrease in endothelial cell density (P = 0.20). Conclusions: Our pilot study demonstrated the feasibility of the novel CXL device for the treatment of keratoconus and indicates the device is ready for larger scale studies with longer follow-up periods. Translational Relevance: The novel CXLens on-eye UVA light-emitting contact lens device offers the potential for efficient, high-throughput transepithelial corneal CXL.