Abstract
Purpose::
To evaluate the optical quality of the Dohlman/Boston keratoprosthesis (Kpro) Type I before and after implantation by measuring higher order aberrations and to compare them to eyes after penetrating keratoplasty (PK) and normal eyes.
Methods::
A Shack-Hartmann wavefront sensor was used to measure higher order aberrations of three Kpro devices. With the same wavefront sensor, the aberrations of five patients with the Kpro implanted were measured for a 3mm pupil with and without the bandage contact lens (BCL). Wavefront aberration data on 378 normal eyes (pre-LASIK) and 14 eyes after PK were adjusted for a 3mm pupil and compared to the Kpro data. The outcome measures used for comparison included Zernike modes up to the 5th order and higher order root mean square (HORMS) wavefront error.
Results::
Average HORMS of the Dohlman/Boston keratoprostheses was 0.11+0.01 µm (average ± standard deviation). Normal pre-LASIK eyes with uncorrected visual acuity between 20/30 and 20/100 had a HORMS of 0.05+0.02 µm. This difference was clinically insignificant (approximately equivalent to 0.17 Diopters of sphere). Kpro patients had a HORMS of 0.30+0.16 and 0.36+0.18 µm with and without the BCL, respectively. These patients had uncorrected visual acuity between 20/25 and 20/60. Post PK eyes had a HORMS of 0.28+0.13 µm and uncorrected visual acuity between 20/30 and 20/200. Second order RMS was 0.83+0.93, 0.47+0.46, 1.10+0.26 and 1.05+0.49 for the Kpro with BCL, Kpro without BCL, PK and normal pre-LASIK eyes, respectively. The Kpro eyes had less 2nd order aberrations than PK and normal pre-LASIK eyes by approximately 1.6 Diopters of sphere.
Conclusions::
It is possible to use wavefront technology to objectively measure the optical quality of keratoprostheses both in vitro and in vivo. To our knowledge, a Kpro device has never been evaluated this way. Higher order aberrations of the Dohlman/Boston keratoprosthesis Type I were clinically similar to that of eyes after PK. The eyes with Kpro had significantly smaller residual refractive errors compared to the PK eyes.
Keywords: keratoprostheses • optical properties