Evaluation of Higher Order Aberrations in Eyes with Dohlman/Boston Keratoprosthesis and Comparison with Penetrating Keratoplasty and Normal Eyes K.Stasi 1, S.Pantanelli 2, R.Sabesan 2, G.Yoon 2, G.J. McCormick 1 and J.V. Aquavella 1. 1 Dept of Ophthalmology, University of Rochester Eye Institute, Rochester, NY; 2 Center for Visual Sciences, University of Rochester, Rochester, NY. Financial Interest Disclosure: K.Stasi, none; S.Pantanelli, none; R.Sabesan, none; G.Yoon, Baush and Lomb; G.J. McCormick, none; J.V. Aquavella, none.

PURPOSE To evaluate: the optical quality of Dohlman/ Boston Keratoprosthesis (KPro) Type I before and after implantation by measuring higher order aberrations how the optical quality of KPro compares to normal eyes and eyes after penetrating keratoplasty

INTRODUCTION The Dolman/ Boston keratoprosthesis (KPro) is an artificial cornea PMMA device, alternative to penetrating keratoplasty (PK) with good anatomic results and quick visual recovery, reserved usually for failed PK patients. KPro patients can have good visual acuity and visual fields (according to their visual potential) as well as very good visualization of the fundus. The wavefront aberrations through this device have not been reported or compared to PK patients or normal subjects. It is also not known how the routine use of bandage contact lens on KPro eyes affects the quality of their vision. The quality of vision can be evaluated with measuring wavefront aberrations (deviation from ideal eye) which include: lower (second) order aberrations (like sph/cyl, correctable w. glasses or CLs, 85% of total normal eye aberrations) and higher order aberrations (not correctable w. glasses or CLs, about 15% of total aberrations) Abnormal eyes such as PK and KCN eyes as well as symptomatic post- LASIK eyes have significantly more higher-order aberrations (HOAs) than normal eyes.

3rd 4th 5th Phase advance Phase delay Higher-order aberrations (not correctable w. Rx, ~15%) 0 Defocus Vertical Coma Horizontal Coma Trefoil Spherical Aberration Secondary Astigmatism Quadrafoil Lower-order aberrations (sph/cyl, correctable w. Rx, ~85%) Astigmatism Pentafoil Secondary Coma Secondary Trefoil Zernike Pyramid 2nd Order aberration Mathematical description of wavefront aberrations: Zernike polynomials

METHODS A Shack-Hartmann large dynamic-range wavefront sensor was used to measure higher order aberrations in the following three groups: (I) KPro devices (n=3) mounted to custom made plastic stand (II) Patients implanted with KPro (n=5), with and without bandage soft contact lens, after dilation (1% tropicamide) (III) Patients after Penetrating Keratoplasty (n=14) and normal pre- LASIK eyes (n=378) wavefront aberration data were adjusted for a 3mm pupil in order to be comparable to Kpro data (3mm is the optical zone of this The higher order aberration root mean square (HORMS) was calculated up to the 5th order as well as the mean and st. deviation of absolute values of each aberration. Lenslet array Pupil camera

RESULTS Keratoprosthesis (Kpro) device HORMS of KPro devices (n=3) was 0.11 ± 0.01μm (average ± standard deviation) HORMS of normal pre-LASIK eyes ± (for 3mm pupil, n=378). HORMS of normal pre-LASIK eyes with uncorrected visual acuity between 20/30 and 20/100 had a HORMS of 0.05 ± 0.02 μm. (for 3mm pupil, n=378). The difference between Kpro and normal eye group was 0.06 μm. This difference is clinically insignificant (approximately equivalent to 0.17 Diopters of sphere).

Kpro patients Five patients implanted with Dolman/ Boston keratoprosthesis with uncorrected visual acuity between 20/30 and 20/60 wearing plano bandage soft contact lens (BCL). Patient #1: slit lamp photo at postop day 1 and fundus photo at postop day 4.

Keratoprostheses and Penetrating Keratoplasty Patients: HORMS, second order RMS (mean+SD) and uncorrected visual acuity (UCVA) HORMS (μm) 2ndRMS (μm) UCVA KPro pts (n=5) with plano BCL 0.30± ± /25-20/60 without BCL0.36 ± ± 0.46 PK pts (n=14)0.28 ± ± /30-20/200 Normal (n=378)0.05 ± ± /30-20/100 For 3mm pupil, Kpro eyes had similar higher order aberrations to PK patients but less second order aberrations than PK and normal pre-LASIK eyes by approximately 0.5μm, clinically equivalent to about 1.6 Diopters of sphere * p= 0.02 t-test Kpro pts and PK pts second order RMS *

Pupil Size (mm) Higher Order Rms Wavefront Error (μm) K pro Pts All Symptomatic LASIK Normal Non-Surgical n=33n=32n=31n=26 *McCormick et al. Higher Order Aberrations in Symptomatic Eyes with Irregular Corneas After Laser Refractive Surgery. Ophthalmology. 112(10): , 2005 Oct. Higher Order aberrations increase with increasing pupil size

Comparison of higher order aberrations from Kpro patients with 3mm optical zone to 6mm pupil data from PK, symptomatic and asymptomatic postLASIK patients, keratoconic and normal eyes. 6mm3mm data for 6mm pupil data for 3mm pupil

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. Research supported in part by a grant from Research to Prevent Blindness