Optical functional properties of the Boston Keratoprosthesis

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optical Science

Background:

• The Boston Keratoprosthesis (KPro) is a device used to restore vision in patients with severe corneal disease.
• Understanding its optical characteristics and potential limitations, such as glare, is crucial for optimizing patient outcomes.

Purpose of the Study:

• To assess the optical performance of the Boston KPro.
• To pinpoint sources of glare and explore methods for glare reduction.
• To evaluate the efficacy of KPro implantation when the fellow eye possesses normal vision.

Main Methods:

• Comparison of computed and measured point spread functions (PSF) and glare.
• Utilizing a translucent cornea model to assess scatter and glare control with a dark-iris contact lens.
• Measuring glare impact using the Brightness Acuity Test (BAT) and evaluating visual fields and stereopsis.

Main Results:

• Boston KPro's optical performance closely approaches the diffraction limit.
• Hazy corneal grafts surrounding the KPro are identified as the primary glare source, controllable with dark-iris contact lenses.
• The fellow eye remains dominant, with KPro implantation providing limited improvement in visual acuity, stereopsis, or binocular visual field.

Conclusions:

• Dark-iris contact lenses can significantly mitigate glare associated with KPro implants.
• KPro implantation in individuals with a visually sound fellow eye does not substantially enhance overall visual function.