Abstract
Purpose :
Studies have shown that lenticules obtained from small incision lenticule extraction (SMILE) can be used as refractive inlays and substrates for cell transplantation. However, the use of these lenticules is limited by the thickness pre-determined by the refractive correction attempted in the donor patients. In this study, we evaluated the feasibility of using an excimer laser to thin and reshape the lenticules.
Methods :
First, fresh human lenticules were subjected to excimer laser ablation for re-shaping. Changes in the surface morphology and surface chemistry were then assessed with scanning electron microscopy (SEM) and atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR), respectively. Second, 107μm-thick porcine lenticules from -6.00D SMILE correction were surface ablated (50% thickness reduction). They were then implanted into a 120μm-deep stromal pocket of porcine corneas ex vivo. Corneal thickness, topography, and refractive properties were assessed before and after implantation.
Results :
SEM and AFM revealed less tissue bridges and a more regular surface on the excimer lasered lenticules, evidenced by the lower Rz value (290.1±96.1nm vs 380.9±92.6nm; p=0.045). FTIR showed profound changes in the lipid profile which was attributed to the photoablative effect on the stromal cells laying close to the lenticule's surface. FTIR revealed that the collagen content was only weakly affected by the laser treatment. The lasered porcine lenticules were thinner than the non-lasered controls (46±3μm vs 57±3μm; p<0.001). After implantation in the porcine cornea, we found that the thicker, non-lasered lenticules yielded a tendency towards a greater increase in axial keratometry (6.63±2.17D vs 5.60±3.79D), elevation (18.6±15.4µm vs 15.2±5.5µm), and refractive power (3.71±5.22D vs 2.17±3.92) compared to the lasered lenticules.
Conclusions :
Excimer laser ablation is feasible for thinning and reshaping SMILE-derived lenticules. However, pre-laser lenticule’s dehydration and amount of lenticule’s bulk removal need to be fine-tuned in order to produce a more accurate and precise alteration to the corneal topography and refractive power.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.