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Optical functional performance of the osteo-odonto-keratoprosthesis
Richard M H Lee1, Gek L Ong, Fook Chang Lam
1*Department of Ophthalmology, Sussex Eye Hospital, Brighton, United Kingdom; †Department of Ophthalmology, Royal Sussex County Hospital, Brighton, United Kingdom; ‡Department of Ophthalmology, Tongdean Eye Clinic, Hove, United Kingdom; and §Department of Optometry and Visual Science, City University London, London, United Kingdom.
Purpose:
The aim of this study was to evaluate optical and visual functional performance of the osteo-odonto-keratoprosthesis (OOKP).
Methods:
Optical design and analysis was performed with customized optical design software. Nine patients with implanted OOKP devices and 9 age-matched control patients were assessed. Contrast sensitivity was assessed and glare effect was measured with a brightness acuity test. All OOKP patients underwent kinetic Goldmann perimetry and wavefront aberrometry and completed the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25).
Results:
Optical analysis showed that the optical cylinder is near diffraction-limited. A reduction in median visual acuity (VA) with increasing glare settings was observed from 0.04 logMAR (without glare) to 0.20 logMAR (with glare at "high" setting) and significantly reduced statistically when compared with the control group at all levels of glare (P < 0.05). Contrast sensitivity was significantly reduced when compared with age-matched controls at medium and high spatial frequencies (P < 0.05). Median Goldmann perimetry was 65 degrees (interquartile range, 64-74 degrees; V-4e isopters) and 69 degrees excluding 2 glaucomatous subjects. Several vision-related NEI VFQ-25 subscales correlated significantly with VA at various brightness acuity test levels and contrast sensitivity at medium spatial frequencies, including dependency, general vision, near activities and distance activities.
Conclusions:
The OOKP optical cylinder provides patients with a good level of VA that is significantly reduced by glare. We have shown in vivo that updates to the optical cylinder design have improved the patient's field of view. Reduction of glare and refinement of cylinder alignment methods may further improve visual function and patient satisfaction.
