Facilitation of ab interno radial keratotomy by air keratoplasty.

BACKGROUND

Ab interno radial keratotomy is a keratorefractive procedure with radial incisions made by externalizing a blade inserted in the deep stroma. A major limitation of the procedure is the technical inability to establish a safe pre-Descemetic stromal entry of the blade with subsequent suboptimal depth of the radial incisions. A technique to delineate Descemet's membrane was investigated to obtain deeper incisions with the ab interno radial keratotomy.

METHODS

Air was injected with a 30-gauge needle mounted on a 3-milliliter syringe and entering the deep stroma at the limbus in human donor eyes. The injection was done in a pulse fashion with the needle tip advanced 3 mm away from the limbus. Ab interno radial keratotomy was then performed with and without air injection.

RESULTS

Bubbles were localized to the pre-Descemet region. The depth of the radial keratotomy incisions increased from 57.7% (SD = 11.5%) without air injection, to 83.0% (SD = 10.6%) with air injection.

CONCLUSIONS

Deep stromal air injection delineates the pre-Descemet space, allowing deeper radial incisions with the ab interno radial keratotomy.