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The Boston keratoprosthesis provides a wide depth of focus
Author(s) -
Sayegh Rony R.,
Dohlman Claes H.,
Greenstein Scott H.,
Peli Eli
Publication year - 2015
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/opo.12181
Subject(s) - dioptre , pupil , optometry , ophthalmology , visual acuity , refractive error , medicine , refraction , focus (optics) , pupil diameter , mathematics , vision disorder , optics , physics
Purpose To measure the through‐focus curve for eyes implanted with a type 1 Boston keratoprosthesis ( KP ro) and compare it to that of pseudophakic controls with fixed pupil sizes. The results should assist in evaluating postoperative visual quality after surgery. They should also help to determine the necessary KP ro inventories in terms of refractive power steps. Methods Autorefraction and manifest refraction were performed on all eyes. The monocular through‐focus acuity curve was plotted in reference to the best‐corrected visual acuity by spectacle plane defocus ranging from +5.00 to −5.00 dioptres in 0.50 dioptre increments. These measurements were obtained on KP ro‐implanted eyes, pseudophakic eyes as controls, and on the same control eyes after fixing the pupil diameter to 3 and 2 mm using black painted iris contact lenses. Results Ten KP ro eyes and five control eyes were included. Good agreement was noted between the subjective refractions and autorefraction in KP ro eyes. The average through‐focus curve for the control eyes was significantly steeper than that of the KP ro curve, but became comparable after fixing the control pupil to 2 and 3 mm. Conclusion The KP ro's wide depth‐of‐focus makes the visual acuity less dependent on an exact refractive correction at distance and explains the ‘pseudoaccomodation’ experienced by these patients. This is primarily due to the small pupil diameter of the KP ro. The current manufacturing steps in 0.50 dioptre increments appears to be sufficient.