Abstract
Purpose: :
To evaluate the optical quality of the Dohlman/Boston keratoprosthesis (Kpro) implanted in patients by measuring higher order aberrations and to compare them to eyes after penetrating keratoplasty (PK) and to normal eyes.
Methods: :
A Shack-Hartmann wavefront sensor was used to measure higher order aberrations in five patients with the Kpro implanted 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 in order to compare to the Kpro with 3mm optical zone 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: :
Kpro patients had uncorrected visual acuity between 20/30 and 20/100. The most prevelant Higher Order Aberrations (HOAs) in Kpro patients were trefoil, coma and quadrafoil, both in patients with and without the bandage contact lens (BCL). Kpro patients had a HORMS of 0.30+0.16 and 0.36+0.18 µm with and without the BCL, respectively (standard deviation values in parenthesis). Post-PK eyes had uncorrected visual acuity between 20/30 and 20/200. The most prevalent HOAs in post-PK patients were coma, trefoil, secondary astigmatism and spherical aberration. Post-PK patients showed HORMS of 2.25+0.98 µm for 6mm pupil. After the measurements were adjusted for 3mm pupil, HORMS was 0.28+0.13 µm in post-PK patients. Normal pre-LASIK eyes with uncorrected visual acuity between 20/30 and 20/100 had a HORMS of 0.05+0.02 µm adjusted for 3mm pupil. 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 the equivalent of approximately 1.6 Diopters of sphere.
Conclusions: :
Higher order aberrations of the Dohlman/Boston keratoprosthesis Type I were clinically similar to that of eyes after PK when adjusted for 3mm pupil, but significantly less when compared to the PK data for 6mm pupil. The Kpro eyes showed significantly smaller residual refractive errors compared to the PK eyes.
Keywords: keratoprostheses • aberrations