Low specificity of scanning laser polarimetry.
OBJECTIVE
Scanning laser polarimetry is used to assess the peripapillary retinal nerve fiber layer. This study evaluates scanning laser polarimetry in normal subjects.


METHODS
28 eyes of 28 normal subjects (age range 21-48 years, mean age 36.5 years) had scanning laser polarimetry (NFA-GDx, Laser Diagnostic Technologies, San Diego, Calif., USA). All subjects had normal eye examinations, refractive errors with spherical equivalents <5 D and astigmatism <2 D, normal intraocular pressures, no history of diseases affecting the visual field or nerve fiber layer, and normal white-on-white automated perimetry (Octopus 101, program G2). The mean image of three good-quality measurements with the scanning laser polarimeter was included.


RESULTS
36% of the normal subjects (10/28) had at least one NFA parameter outside normal (p < 0.05). The parameters most frequently found to be outside normal were symmetry (21%, 6/28) and superior ratio (17%, 5/28).


CONCLUSIONS
Scanning laser polarimetry is often used for early detection of glaucomatous damage in glaucoma suspects. This study found a specificity of only 64% and indicates that the actual selection of parameters is not adequate. Especially the parameters symmetry and superior ratio should be reevaluated in order to achieve a higher specificity.
Mojon
Daniel S
DS
Department of Strabismus and Neuro-Ophthalmology, Kantonsspital, St Gallen, Switzerland. daniel.mojon@kssg.ch
D000328:Adult; D003941:Diagnostic Techniques, Ophthalmological / Q000592:standards*; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers; D009798:Ocular Hypertension / Q000175:diagnosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity