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Abstract
Millions of people worldwide are bilaterally blind due to corneal diseases including infectious etiologies, trauma, and chemical injuries. While corneal transplantation can successfully restore sight in many, corneal graft survival decreases in eyes with chronic inflammation and corneal vascularization. Additionally, the availability of donor cornea material can be limited, especially in underdeveloped countries where corneal blindness may also be highly prevalent. Development of methods to create and implant an artificial cornea (keratoprosthesis)may be the only option for patients whose eye disease is not suitable for corneal transplantation or who live in regions where corneal transplantation is not possible. The Boston keratoprosthesis (B-KPro) is the most commonly implanted keratoprosthesis worldwide, having restored vision in thousands of patients. This article describes the initial design of the B-KPro and the modifications that have been made over many years. Additionally, some of the complications of surgical implantation and long-term care challenges, particularly complicating inflammation and glaucoma, are discussed. Expected final online publication date for the Annual Review of Vision Science, Volume 8 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Claes Dohlman
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA;
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Hui PC, Pereira LA, Dore R, Chen S, Taniguchi E, Chodosh J, Dohlman CH, Paschalis EI. Intrinsic Optical Properties of Boston Keratoprosthesis. Transl Vis Sci Technol 2020; 9:10. [PMID: 33200051 PMCID: PMC7645245 DOI: 10.1167/tvst.9.12.10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/07/2020] [Indexed: 12/03/2022] Open
Abstract
Purpose 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 Standardization–certified 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 manufacturer-reported 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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Affiliation(s)
- Pui-Chuen Hui
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.,Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Leonardo A Pereira
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.,CAPES Foundation, Ministry of Education of Brazil, Brasilia, Brazil
| | - Renald Dore
- University of Rochester, Institute of Optics, Rochester, NY, USA
| | - Shengtong Chen
- University of Rochester, Institute of Optics, Rochester, NY, USA
| | - Elise Taniguchi
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.,Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - James Chodosh
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Claes H Dohlman
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.,Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Eleftherios I Paschalis
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.,Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
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