['To measure the through-focus curve for eyes implanted with a type 1 Boston keratoprosthesis (KPro) 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 KPro inventories in terms of refractive power steps.', '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\xa0dioptres in 0.50\xa0dioptre increments. These measurements were obtained on KPro-implanted eyes, pseudophakic eyes as controls, and on the same control eyes after fixing the pupil diameter to 3 and 2\xa0mm using black painted iris contact lenses.', 'Ten KPro eyes and five control eyes were included. Good agreement was noted between the subjective refractions and autorefraction in KPro eyes. The average through-focus curve for the control eyes was significantly steeper than that of the KPro curve, but became comparable after fixing the control pupil to 2 and 3\xa0mm.'] Does the Boston keratoprosthesis provide a wide depth of focus?