advertisement
Abstract #6315 Published in IGR 3-2
Stability of corneal polarization axis measurements for scanning laser polarimetry
Greenfield DS; Knighton RWOphthalmology 2001; 108: 1065-1069
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: A prospective, noncomparative case series. PARTICIPANTS: Persons with normal corneas were enrolled; eyes with less than one year of follow-up from the initial CPA measurement were excluded. INTERVENTION: The authors 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: CPA measurements. RESULTS: Seventy-one eyes of 30 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, 50° nasally downward to 14° nasally upward). The mean change in CPA was 4.1 ± 3.2° (range, 0-13°). CPA stability was statistically associated with the mean (initial and repeat) CPA (R2 = 0.01; p = 0.009), but not with age (R2 = 0.0003; p = 0.9) or gender (R2 = 0.03; p = 0.2). CONCLUSIONS: CPA measurements have good one-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.
Dr D.S. Greenfield, Bascom Palmer Eye Institute, 7108 Fairway Drive, Suite 340, Palm Beach Gardens, FL 33418, USA. dgreenfield@bpei.med.miami.edu
Classification:
2.2 Cornea (Part of: 2 Anatomical structures in glaucoma)
2.13 Retina and retinal nerve fibre layer (Part of: 2 Anatomical structures in glaucoma)
6.9.1 Laser scanning (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis)