Calculation of power and field of view of keratoprostheses

Langenbucher, Achim; Szentmáry, Nóra; Speck, Alexis; Seitz, Berthold; Eppig, Timo

doi:10.1111/opo.12046

Cited by 9 publications

(10 citation statements)

References 19 publications

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“…On the other hand side, there are reports that the central visual field is not affected with implantation of those inlays [23, 26], but detailed clinical data has not been published up to now. Especially, the mid-to-peripheral visual field may be affected by a KAMRA, as it has been shown for other aperture restricting optical implants such as keratoprostheses [36]. Therefore, in the present paper, we address the effect of light attenuation for variations of field angle and pupil size in an optical simulation model.…”

Section: Discussionmentioning

confidence: 94%

Vignetting and Field of View with the KAMRA Corneal Inlay

Langenbucher

Goebels

Szentmáry

et al. 2013

BioMed Research International

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Purpose. To evaluate the effect of the KAMRA corneal inlay on the retinal image brightness in the peripheral visual field. Methods. A KAMRA inlay was “implanted” into a theoretical eye model in a corneal depth of 200 microns. Corneal radius was varied to a steep, normal, and flat (7.37, 7.77, and 8.17 mm) version keeping the proportion of anterior to posterior radius constant. Pupil size was varied from 2.0 to 5.0 mm. Image brightness was determined for field angles from −70° to 70° with and without KAMRA and proportion of light attenuation was recorded. Results. In our parameter space, the attenuation in brightness ranges in between 0 and 60%. The attenuation in brightness is not affected by corneal shape. For large field angles where the incident ray bundle is passing through the peripheral cornea, brightness is not affected. For combinations of small pupil sizes (2.0 and 2.5 mm) and field angles of 20–40°, up to 60% of light may be blocked with the KAMRA. Conclusion. For combinations of pupil sizes and field angles, the attenuation of image brightness reaches levels up to 60%. Our theoretical findings have to be clinically validated with detailed investigation of this vignetting effect.

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Section: Discussionmentioning

confidence: 94%

Vignetting and Field of View with the KAMRA Corneal Inlay

Langenbucher

Goebels

Szentmáry

et al. 2013

BioMed Research International

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“…A plethora of studies have been conducted regarding the clinical outcomes of B-KPro surgery, yet very few reports focused on the optical properties of the device and its intrinsic ability to provide normal vision. [10][11][12]17 There has been confusion as to whether poor visual outcomes in some patients could be attributed to optical limitations of the device. The present study was designed to reevaluate the optics of the type I B-KPro, validate the manufacturing process and specifications, and determine the optical limits in achieving normal, reasonably glare-free visual acuity.…”

Section: Discussionmentioning

confidence: 99%

“…The surgical and clinical outcomes of patients implanted with the B-KPro have been previously published to elucidate the clinical performance of the device, 8 , 9 and help surgeons optimize patient selection and reduce postoperative surgical complications. A few studies have detailed the optical performance of the B-KPro, 10 – 12 however, a detailed evaluation of the intrinsic optical performance of the B-KPro simulating an aqueous environment has not been performed to International Organization for Standardization (ISO) standard bench-top methods. We have addressed this gap by adopting the ISO standards for implantable intraocular lenses (IOLs) for benchmarking the optical properties of the B-KPro type I device, which is the most frequently implanted B-KPro type.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic Optical Properties of Boston Keratoprosthesis

Hui

Pereira

Dore

et al. 2020

Trans. Vis. Sci. Tech.

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To benchmark the optical performance of Boston Keratoprosthesis (B-KPro). Methods: Back focal lengths (BFL) of B-KPros for various eye axial lengths were measured using an optical bench, International Organization for Standardizationcertified for intraocular lens characterization, and compared against manufacturer's specification. The modulation transfer function (MTF) and the resolution efficiencies were measured. The theoretical geometry-dependent higher-order aberrations (HOA) were calculated. The devices were characterized with optical profilometry for estimating the surface scattering. Aberration correction and subsequent image quality improvement were simulated in CODE-V. Natural scene-imaging was performed in a mock ocular environment. Retrospective analysis of 15 B-KPro recipient eyes were presented to evaluate the possibility of achieving 20/20 best-corrected visual acuity (BCVA). Results: BFL measurements were in excellent agreement with the manufacturerreported values (r = 0.999). The MTF specification exceeded what is required for achieving 20/20 visual acuity. Astigmatism and field curvature, correctable in simulations, were the primary aberrations limiting imaging performance. Profilometry of the anterior surface revealed nanoscale roughness (root-mean-square amplitude, 30-50 nm), contributing negligibly to optical scattering. Images of natural scenes obtained with a simulated B-KPro eye demonstrated good central vision, with 10/10 visual acuity (equivalent to 20/20). Full restoration of 20/20 BCVA was obtainable for over 9 years in some patients. Conclusions: Theoretical and experimental considerations demonstrate that B-KPro has the optical capacity to restore 20/20 BCVA in patients. Further image quality improvement can be anticipated through correction of HOAs. Translational Relevance: We establish an objective benchmark to characterize the optics of the B-KPro and other keratoprosthesis and propose design changes to allow improved vision in B-KPro patients.

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“…The 16 papers included in this special issue cover a range of advances in these topics including the use of alternative basis functions for wavefront representation and beam generation, keratoprostheses and intraocular lenses, determination and analysis of aberrations, accommodation, retinal imaging, and strabismus …”

mentioning

confidence: 99%

“…Although corneal transplantation is a possible solution the limited availability of donor eyes and possible graft rejection makes the need for artificial corneas an attractive alternative. The study by Langenbucher et al . employs raytracing and PSF calculations to examine the optical consequences of commercially‐available Boston I and Boston II keratoprostheses and the potential of restoring even binocular vision.…”

mentioning

confidence: 99%