Abstract
Purpose :
To determine if the aperture of the Boston keratoprosthesis (Kpro) type I and II device causes visual field defects on standard white-on-white perimetry in eyes without glaucoma. It is critical to know what should be expected for baseline visual field testing in Kpro eyes without glaucoma, in order to accurately assess for any progressive restriction in peripheral vision, which may herald the onset of glaucoma, one of the leading causes of irreversible blindness in Kpro patients.
Methods :
We performed a retrospective chart review and analyzed the Humphrey visual field 24-2 testing (HVF Swedish Interactive Threshold Algorithm standard 24-2 test, Humphrey visual field analyzer Carl Zeiss Meditec, Inc., Dublin, CA) of patients aged 18 and older who had undergone Boston Kpro I or II surgery from January 1, 1990 to June 1, 2021 and who did not have glaucoma at the time of visual field testing. Patients were included if their central vision was 20/40 or better with correction. Patient were excluded if they had poor reliability indices (i.e. more than 33% fixation losses, false positives, and/or false negatives) or if they had any other non-glaucomatous disease that could independently affect their HVF test results.
Results :
Out of 414 Kpro I eyes (of 389 patients) and 90 Kpro II eyes (of 78 patients) analyzed, 9 patients (4 Kpro I and 5 Kpro II) met the inclusion and exclusion criteria. We analyzed 36 HVFs of these 9 patients: 14 HVFs of 4 Kpro I patients and 22 HVFs of 5 Kpro II patients. Of the 14 Kpro I HVFs, 9 (64.3%) were full fields, 3 (21.4%) had a rim artifact, and 2 (14.3%) had a borderline superior nasal step. Of the 22 Kpro II HVFs, 10 (45.5%) of the Kpro II HVFs were full fields, 9 (40.9%) had a rim artifact, 2 (9.1%) had a rim artifact with borderline inferior nasal step, and 1 (4.5%) had a significant lid artifact. Seven of 9 patients had at least one full field, with the last two patients having a rim artifact and a rim artifact with a borderline inferior step.
Conclusions :
Kpro I and II devices do not significantly affect peripheral vision on HVF SITA standard 24-2 testing in eyes without glaucoma. The most common artifact in Kpro patients was the rim artifact, affecting only the outermost testing points.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.