Abstract
Purpose:
To assess the potential optical quality of a lamellar keratoprosthesis device and to assess the ability of this device to visual rehabilitation in complex corneal and anterior segment disease
Methods:
Part 1: Diseased corneal tissue with edema from non-functioning corneal endothelium was removed using a femtosecond laser. 100um, 200um, 300um and 400um of tissue was placed behind a lamellar keratoprosthesis device to determine potential optical quality using optical bench techniques and wavefront aberrometry (WA) Part 2: A case review of a patient with multiple corneal transplant failures and multiple glaucoma procedures OU with contralateral keratoprostheses of two different types was performed.
Results:
Part 1: Optical quality decreases with increasing diseased corneal tissue thickness. This decrease in optical quality as measured by WA appears to be non-linear. The subjective visual quality of the lamellar device with 100um of residual tissue is significantly different from other thicknesses. Illumination through tissue is significant at 100um vs 400um (p<0.01) Part 2: The patient's corrected acuity (he is aphakic OU) was 20/400 in the eye with a penetrating keratoprosthesis (limited by congenital glaucoma). His acuity was 20/100+1 (improved from HM) in the eye with the lamellar keratoprosthesis with 280um of residual edematous corneal tissue. Total corneal power was estimated using anterior segment OCT and a modification of the lamellar keratoprosthesis was performed to better match the high keratometry due to buphthalmos from congenital glaucoma. The patient has noted a significant improvement in the quality of life with the implantation of his lamellar keratoprosthesis although he may not be at his best visual potential.
Conclusions:
Although optical quality is improved with less residual corneal tissue in a lamellar keratoprosthesis, residual tissue may still allow for very functional vision and a significant improvement in the quality of life for these complex corneal patients. The concept of a lamellar keratoprosthesis that does not necessarily unlock the full optical potential of the eye, but achieves a functional improvement in acuity with a potentially lower risk may be a potentially new paradigm in keratoprosthesis surgery. Further follow-up is necessary to assess the long term results.
Keywords: 575 keratoprostheses •
479 cornea: clinical science •
478 contrast sensitivity