EX-VIVO STUDY ON SURFACE QUALITY OF CORNEAL LENTICULE AND STROMA AFTER LOW ENERGY FEMTOSECOND LASER LENTICULE EXTRACTION

To assess the surface quality of cap, stroma and lenticular surfaces created using low energy femtosecond laser lenticule extraction (Ziemer FEMTO LDV Z8)

Laboratory study

Freshly isolated porcine eyes (n=24) were divided into 4 groups (n=6 each): two with optimal laser power settings (32%) with posterior curvature equivalent to a sphere correction of -2D and -5D respectively and other two with high power settings (64%) with sphere correction of -2D and -5D respectively. After suitable dissection by a single surgeon and standard processing, samples were analysed via scanning electronic microscopy (SEM). Surface morphology was evaluated using previously published scoring system; surface relief, surface regularity, extent and position of irregularities were graded by four independent clinicians.

Eyes with optimal laser power settings (32%) and correction of -2D had significantly less size of irregular area as compared to those with -5D correction; however, no significant difference was found between the two groups with higher laser power (64%). When comparing eyes with -2D correction, size of the irregular area was significantly lesser with optimal laser power group. Surface relief was significantly lesser with -5D correction in optimal laser power group as compared to high power laser group. 

Low energy femtosecond laser lenticule extraction (Ziemer FEMTO LDV Z8) produces good surface quality results. In general, there is a tendency for smoother surface stromal quality with lower laser power settings as compared to higher power.