Reproducibility of retinal nerve fiber layer thickness measurements using scanning laser polarimetry in pseudophakic eyes.
OBJECTIVE
To assess the reproducibility of retinal nerve fiber layer measurements in pseudophakic normal and glaucomatous eyes using scanning laser polarimetry (GDx, Laser Diagnostic Technologies, Inc., San Diego, CA).


METHODS
Normal and glaucomatous patients with polymethylmethacrylate posterior chamber intraocular lenses that satisfied entry criteria underwent imaging by two experienced operators. Eyes with posterior capsule opacification or vision less than 20/30 were excluded. Baseline images (mean pixel SD less than 8 mm) were obtained on 3 separate days within a 7-week period. Reproducibility, defined as the pooled within eye variance of these 3 measurements and the coefficient of variation for 12 retardation parameters generated by GDx software were calculated.


RESULTS
Eighteen eyes (11 glaucoma, 7 normal) of 15 patients (7 female, 8 male) were enrolled (mean age 78 +/- 6 years). Among glaucomatous eyes, the average mean deviation and corrected pattern standard deviation using achromatic automated perimetry (Zeiss-Humphrey, Dublin, CA) was -3.8 +/- 1.5 dB (range, -1.89 to -5.04 dB) and 4.9 +/- 3.3 dB (range 0 to 11.05 dB), respectively. Coefficient of variation was 10% or less for all retardation parameters except ellipse modulation (20.2%) and neural network number (12.4%). Glaucomatous and normal eyes had similar variability for 8 of 12 (66.7%) retardation parameters. Inferior ratio, ellipse modulation, and superior ratio were significantly less variable in glaucomatous eyes (P = 0.007, 0.02, and 0.04 respectively) than normal eyes. Superior integral was more variable in glaucomatous eyes (P = 0.03).


CONCLUSIONS
Retardation measurements may be obtained in pseudophakic eyes with acceptable reproducibility. Normal eyes and eyes with mild glaucomatous damage have similar variability for most retardation parameters.
Rhee
Douglas J
DJ
Bascom Palmer Eye Institute, University of Miami School of Medicine, Florida, USA.
Greenfield
David S
DS
Chen
Philip P
PP
Schiffman
Joyce
J
D000368:Aged; D000369:Aged, 80 and over; D001718:Birefringence; D005260:Female; D005902:Glaucoma, Open-Angle / Q000150:complications*; D006801:Humans; D007834:Lasers; D008297:Male; D009412:Nerve Fibers / Q000473:pathology*; D009900:Optic Nerve / Q000473:pathology*; D019591:Pseudophakia / Q000150:complications*; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D058609:Visual Field Tests / Q000379:methods*