Rates of retinal nerve fibre layer thickness change in glaucoma patients and control subjects.
OBJECTIVE
To examine the rates of retinal nerve fibre layer thickness (RNFLT) change in glaucoma patients and healthy, age-similar control subjects with three techniques: scanning laser polarimetry with variable corneal compensation (VCC) and enhanced corneal compensation (ECC), and time-domain optical coherence tomography (OCT).


METHODS
Sixty-one patients and thirty-three controls were examined with each technique and with standard automated perimetry (SAP) every 6 months. Rates of global RNFLT change and SAP mean deviation (MD) change were estimated with linear mixed-effects models.


RESULTS
The median (interquartile range) baseline age was 64.4 (58.2, 71.0) years for patients and 62.4 (56.3, 70.1) years for controls (P=0.56). There was a median of seven examinations over 3.1 years for patients and six examinations in 3.0 years for controls. Baseline visual field MD and RNFLT for all imaging modalities were significantly lower (P<0.01) in patients compared with controls. Rates of RNFLT change were not significantly different between patients and controls (P≥0.19). Mean rates of VCC-measured RNFLT change were -0.18 and -0.37 μm per year in patients and controls, whereas the respective figures for ECC and OCT were -0.13 and -0.31 μm per year, and 0.04 and 0.61 μm per year. Mean rates of MD change were -0.20 and 0.03 dB per year in patients and controls, respectively (P=0.01).


CONCLUSIONS
Rates of RNFLT change in glaucoma patients were not statistically different from control subjects for any modality. A significantly negative rate of MD change in patients suggests a genuine, continued deterioration in these patients not reflected by RNFLT changes.
Department of Ophthalmology and Visual Sciences, Dalhousie University, Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia, Canada.
N
N
O'Leary
P H
PH
Artes
D M
DM
Hutchison
M T
MT
Nicolela
B C
BC
Chauhan
D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology; D011446:Prospective Studies; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D057109:Scanning Laser Polarimetry; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence / Q000379:methods; D058609:Visual Field Tests; D014794:Visual Fields