Abstract
Purpose::
Modern corneal laser surgery for the correction of optical errors of the eye requires a precise, reliable and reproducible creation of corneal flaps. The use of ultra-short laser pulses with pulse durations of a few 100 femtoseconds (250 fs) allows for non-thermal cuts of ocular tissue with very good predictability. These study objectives to analyse flap diameter and thickness predictability and reproducibility and also the cutting quality performed in porcine eyes by "Da Vinci" femtosecond microkeratome.
Methods::
It was studied the prospective outcomes of 12 fresh porcine cadaver eyes that underwent flap creation with the "DaVinci" Femtosecond Laser Microkeratome model 2 (Femto LDV, Ziemer Ophthalmic System AG, Port, Switzerland). The flap thickness were determined for 110µm using the suction ring type 9.0 P2. Homogeneity and predictability of the flap creation were analyzed by microscopy and photography examination.The flap diameter was measured using a calliper and the flap thickness with a calibrated mechanical micrometer. The stromal bed and edge quality and also the ability to perform the flap opening were subjectively evaluated and scaled from 1 to 4, in which 1 meant not acceptable, 2 moderate, 3 very good and 4 was scaled for the best quality.
Results::
The mean flap thickness was 114.25±6.94µm, ranged from 105 to 120µm. The mean flap diameter was 8.68±0.38mm. The stromal bed homogeneity was scaled 3 in all cases. 83.3% of cases the stromal edge was classified for ≥3. The facility to lift the flap was scaled for ≥3 in 92% of cases. None has been scaled as "not acceptable".
Conclusions::
A good flap thickness predictability with a 114µm (goal was 110µm) and a good reproducibility of less than 7µm (standard deviation) were found. The test series also showed good flap diameter reproducibility with a variation of less than 4% of the mean diameter.Subjective analysis of the stromal surface, edge quality and flap lifting showed very good reliability and reproducibility.
Keywords: refractive surgery: other technologies • refractive surgery: LASIK • refractive surgery: optical quality