Management of small-incision lenticule extraction ectasia using tissue addition and pocket crosslinking

Lamellar surgeries with SMILE-derived lenticules

PURPOSE

Lamellar surgeries with SMILE lenticules are an evolving field of refractive surgery. This chapter intends to discuss the reported clinical results of using SMILE derived lenticules in terms of feasibility, safety and predictability; or the potential management of hyperopia, keratoconus, SMILE ectasia and presbyopia.

MATERIALS AND METHODS

Donor SMILE lenticules were prepared under microscope tocreate doughnut shaped lenticules. For hyperopia, this tissue was then inserted into afemtosecond laser enabled pocket created using VisuMax FS Laser at a depth of 160µm. For ectasia induced by keratoconus and post refractive procedure (SMILE), 0.23% riboflavin dye was instilled into the interface and then lenticule was inserted followed by exposure to UV-A radiation with total energy of 6.3 J.

RESULTS

Spherical equivalent (S.E.) of within ± 0.5 D was observed in 50% (n=21) eyes and within 1 D was seen in 71% eyes treated for hyperopia. A significant increase in the K mean anterior, central corneal thickness, Q-value and corneal aberrations was seen 2 weeks post-op. Clinical improvement in terms of S.E. and uncorrected distance visual acuity in eyes treated for ectasia after keratoconus and post refractive procedure (SMILE) was seen.

CONCLUSION

With the ample availability of SMILE- derived lenticules, researchers are exploring the possibility of using this tissue for the treatment of various refractive and corneal conditions.

Incidence of Ectasia After SMILE From a High-Volume Refractive Surgery Center in India

PURPOSE

To report the incidence of ectasia after small incision lenticule extraction (SMILE) in a high-volume refractive surgery center in India.

METHODS

To derive the incidence of ectasia after SMILE, all eyes that underwent SMILE or SMILE Xtra (SMILE combined with prophylactic accelerated corneal cross-linking) from November 2012 to August 2019 were retrospectively analyzed. Furthermore, these cases were classified as being "normal" or "borderline" based on certain predefined criteria. Only eyes with a minimum follow-up of 12 months were included.

RESULTS

Of the total 7,024 eyes analyzed, 6,619 eyes underwent SMILE, of which 10 eyes developed ectasia at a mean interval of 21.3 months, making the incidence of ectasia after SMILE 0.15%. Of these 10 eyes with ectasia, 2 eyes had normal preoperative topography, whereas the remaining 8 eyes were borderline as per the predefined criteria. Retrospective data analysis revealed that 6,025 of 7,024 eyes were normal and thus suitable for a standard SMILE procedure, whereas 999 eyes were borderline, of which 594 eyes underwent SMILE and 405 eyes underwent SMILE Xtra. The incidence of ectasia in borderline eyes undergoing SMILE was 0.80% (8 of 999) versus 0% (none) for borderline eyes undergoing SMILE Xtra (chi square, P < .05).

CONCLUSIONS

The incidence of ectasia after SMILE in the early postoperative period was 0.15%, with borderline eyes accounting for most cases. Borderline eyes treated with SMILE Xtra did not progress to ectasia, potentially suggesting a protective role of simultaneous CXL. [J Refract Surg. 2021;37(12):800-808.].