Surgical Technique:

The Schanzlin Ocular (Laser) Shield(s) was designed to protect the anterior surface of the eye during laser refractive surgery. The instrument when used properly provides protection to the corneal epithelium beyond the flap and to the flap hinge in LARK cases. The instrument is especially useful in cases with small diameter flaps where large diameter treatment zones are necessary, such as with the treatment of consecutive hyperopia after a LARK for myopia.

The instruments consist of large diameter stainless steel domes that have been formed to match the shape of the anterior surface of the eye. The surface of the shield that comes in contact with the eye has been coated and polished to a mirror surface to avoid any abrasion to the cornea or conjunctiva. The interiors of the shields are cut out with diameters of 8.0, 8.5, 9.0, 9.5, and 10.0 mm and along one edge there is a flattened area to protect the flap. There is a small nub at the opposite end to provide a surface for grasping the shield with a forceps. As with all new stainless steel surgical instruments, the Schanzlin Ocular (Laser) Shield(s) should be thoroughly cleaned and sterilized prior to use.

In cases of LARK enhancement or hyperopic LASIK the flap is reflected back and the diameter of the corneal flap is measured with a caliper. A shield is selected with an inner diameter to match the flap diameter. The shield is positioned over the reflected flap and aligned to match the outer flap diameter. If the shield is positioned in this manner, then the corneal epithelial surface outside the area of the flap and the flap hinge will be shielded from any laser energy that goes beyond the flap diameter.

I have used these shields in cases where I needed to do a hyperopic pattern to treat a consecutive hyperopia after myopic LASIK. In these cases the hyperopic pattern had an outer diameter of 9.0 mm and the previous flap diameter was 8.5 mm. By using the corneal shield in the manner described above I was able to deliver the hyperopic pattern without causing any epithelial erosion along the edge of the flap. Similarly, the hinge of the flap was protected.
 
I have also routinely use the shield during cases of hyperopic LASIK to protect the hinge of the flap. In these cases generally a larger corneal shield is utilized. Again the shield size is chosen based on the measured diameter of the flap.

The corneal shield is easy to use and to date I have not had any problems with movement of the shield during the delivery of the laser pattern. Care should be exercised, however, to insure that the shield is not contacting the upper or lower lid since movement of the eye could cause the shield to make contact resulting in dislodging of the shield.