Stability of corneal polarization axis measurements for scanning laser polarimetry

David Greenfield, Robert W. Knighton

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

Objective: Corneal polarization axis (CPA) has been reported to affect retardation measurements obtained with scanning laser polarimetry. The purpose of this investigation was to evaluate the longitudinal stability of CPA measurements. Design: Prospective, noncomparative case series. Participants: Persons with normal corneas were enrolled; eyes with less than 1 year of follow-up from the initial CPA measurement were excluded. Intervention: We constructed a noninvasive slit-lamp-mounted device incorporating two crossed linear polarizers and an optical retarder to measure the slow axis of corneal birefringence, or CPA. Main Outcome Measures: Corneal polarization axis measurements. Results: Seventy-one eyes of 40 individuals (23 female, 17 male) were enrolled in this investigation (mean age, 42.9 ± 13.6 years; range, 22-85 years). Initial CPA measurements (mean, 24.0 ± 18.0° nasally downward; range, 67° downward to 13° nasally upward) were strongly associated (R2 = 0.88; P < 0.0001) with repeat CPA measurements (mean, 20.9 ± 14.6° nasally downward; range, 59° nasally downward to 14° nasally upward). The mean change in CPA was 4.1 ± 3.2° (range, 0-13°). Corneal polarization axis stability was statistically associated with the mean (initial and repeat) CPA (R2 = 0.1; P = 0.009), but not associated with age (R2 = 0.0003; P = 0.9) or gender (R2 = 0.03; P = 0.2). Conclusions: Corneal polarization axis measurements have good 1-year stability. These data suggest that CPA should not contribute significantly to longitudinal measurements of retinal nerve fiber layer thickness obtained with scanning laser polarimetry.

Original languageEnglish
Pages (from-to)1065-1069
Number of pages5
JournalOphthalmology
Volume108
Issue number6
DOIs
StatePublished - Jun 13 2001

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ASJC Scopus subject areas

  • Ophthalmology

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