Scanning laser polarimetry quantification of retinal nerve fiber layer thinning following optic neuritis.
BACKGROUND
Several studies with optical coherence tomography (OCT) have demonstrated thinning of the retinal nerve fiber layer (RNFL) in patients with optic neuritis and multiple sclerosis. Similar studies have not been performed with scanning laser polarimetry (SLP), which relies on different physical phenomena. This study was designed to use SLP to measure axonal loss following a single episode of optic neuritis and to determine if there is a relationship between the degree of axonal loss and the degree of residual visual dysfunction.


METHODS
Twenty-five patients with a single episode of optic neuritis and 15 control subjects were studied with SLP using the GDxVCC device to determine RNFL thickness in relation to visual acuity, visual fields, color vision, visual evoked potentials (VEPs), and previously published OCT data.


RESULTS
SLP detected significant RNFL thinning in affected eyes compared to clinically unaffected fellow eyes in patients and in control eyes (P < 0.001). Reduced RNFL thickness was associated with significantly worse logMAR visual acuity, visual field mean deviation, and color vision. RNFL thinning correlated with reduced whole visual field and central visual field measures and VEP amplitudes. Superior and inferior quadrant RNFL thinning was related to corresponding regional visual field loss. There was a scaling factor between SLP and OCT RNFL measurements but only modest agreement.


CONCLUSIONS
SLP detected functionally relevant axonal loss in eyes affected by optic neuritis. There was a scaling factor between RNFL measurements obtained with SLP and OCT but only modest agreement. Care should therefore be taken when comparing RNFL data from studies using these different devices.
NMR Research Unit, Department of Neuroinflammation, Institute of Neurology, University College London, United Kingdom. a.trip@ion.ucl.ac.uk
S Anand
SA
Trip
Patricio G
PG
Schlottmann
Stephen J
SJ
Jones
Constantinos
C
Kallis
Daniel R
DR
Altmann
David F
DF
Garway-Heath
Alan J
AJ
Thompson
Gordon T
GT
Plant
David H
DH
Miller
D000328:Adult; D055253:Color Vision / Q000502:physiology; D004569:Electroencephalography / Q000379:methods; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology / Q000503:physiopathology; D009412:Nerve Fibers / Q000473:pathology*; D009902:Optic Neuritis / Q000473:pathology* / Q000503:physiopathology*; D010775:Photic Stimulation / Q000379:methods; D012160:Retina / Q000473:pathology*; D057109:Scanning Laser Polarimetry / Q000379:methods; D013223:Statistics as Topic; D014787:Vision Tests / Q000379:methods; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult