Femtosecond laser-assisted posterior lamellar keratoplasty: initial studies of surgical technique in eye bank eyes.
OBJECTIVE
To perfect the technique of femtosecond laser-assisted cutting of the lamellar corneal disc in posterior lamellar keratoplasty.


METHODS
Experimental study.


METHODS
The femtosecond laser was used to make the posterior corneal lamellar interface and trephine (side) cut in 20 eye bank globes and 9 eye bank corneoscleral buttons. Laser parameters were energy 7.4+/-0.1 microJ (lamellar cut) and 8.7+/-0.1 microJ (trephination cut), spot size 2.4 microm, firing rate 15 kHz, and trephination diameter 6.0 to 8.0 mm. The thicknesses of the excised corneal discs were measured with a digital micrometer and compared with values calculated from the laser treatment parameters and the preoperative ultrasound pachymetric readings. The cut surfaces were examined by light microscopy and scanning electron microscopy. In globes, the corneal disc was removed from the eye after laser treatment through a blade incision in the peripheral cornea. In corneoscleral buttons, the posterior disc was peeled off the cornea with forceps after laser treatment on an artificial anterior chamber device. In simulated transplantation, the excised corneal disc was placed into the posterior stromal bed in 7 globes.


RESULTS
The femtosecond laser was successful in making posterior lamellar and trephination cuts in cornea. The cut surfaces were of very good quality with straight, orthogonal edges, albeit with a mild stucco texture of the lamellar stromal surfaces. In 3 globes, the lamellar surface showed shallow concentric ridges. The measured thickness of the excised discs was 55+/-61 microm thicker than the preoperatively predicted values.


CONCLUSIONS
These preliminary studies show that the femtosecond laser can make nonmechanical cuts for posterior lamellar keratoplasty with relative ease and reliability, thus facilitating the most technically difficult step in this surgery.
Soong
H Kaz
HK
Division of Cornea, External Disease, and Refractive Surgery, Department of Ophthalmology, W.K. Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, Michigan 48105, USA. hksoong@umich.edu
Mian
Shahzad
S
Abbasi
Omar
O
Juhasz
Tibor
T
D003315:Cornea / Q000601:surgery* / Q000648:ultrastructure; D016039:Corneal Transplantation / Q000295:instrumentation / Q000379:methods*; D005125:Eye Banks; D006801:Humans; D053685:Laser Therapy / Q000295:instrumentation / Q000379:methods*; D008855:Microscopy, Electron, Scanning