Abstract
Purpose: :
To demonstrate the feasibility of novel applications of femtosecond laser for deep anterior lamellar keratoplasty (DALK). To compare the measured lamellar disc and residual stroma dimensions and the predicted values. To evaluate the residual stromal bed thickness after different techniques.
Methods: :
Corneoscleral buttons preserved at 4° C in tissue storage medium (Optisol-GS, Bausch and Lomb Surgical, Rochester, NY) were obtained from the Eye Bank. Eye bank corneoscleral buttons will be removed from Optisol-GS solution and placed in an artificial anterior chamber device (Moria, Antony, France). The scleral rims were secured and mounted in the artificial anterior chamber device. The artificial anterior chamber were filled with balanced salt solution and the intraocular pressure was maintained at approximately 40 mmHg. The femtosecond laser with 60 khz (Intralase, AMO, CA) is used for side cuts. The depth of the trephination will be 30µm deeper than the lamellar cut depth to ensure that the 2 cuts meet. Energy levels used for the trephination will be deliberately set high (1.95 µJ) to ensure complete detachment of the peripheral edges in deep stroma in edematous corneas. After completion of trephination, the side cut and the lamellar interface will be swept open with a Suarez spleader either manually or after air injection. The central and peripheral corneal thicknesses in the corneoscleral buttons were measured with an ultrasonic pachymeter. Also, different techniques of DALK will be compared.
Results: :
Eight of 20 eyes underwent femtosecond assisted ring-DALK. Four of 8 eyes perforated during procedure. Two eyes perforated during femtosecond application and 2 eyes perforated during lamellar dissection and or air injection. The mean residual stromal bed thickness (RSB) of 4 eyes was 192 ± 46 µm (112 to 236). Six of 20 eyes underwent FS-Assisted DALK with "Zig-zag" side-cut and air assisted dissection "big-bubble" technique. One of 3 eyes perforated during dissection and 2 of 3 eyes had mean RSB of 65 µm (59 and 71). Four of 20 eyes underwent Manual trephination with Barron vacuum trephine (as a control group) and 4 of 5 eyes perforated during lamellar dissection. 1 of 5 eye had an of RSB of 188 microns.
Keywords: cornea: clinical science • depth • laser