The influence of age, sex, race, refractive error and optic disc parameters on the sensitivity and specificity of scanning laser polarimetry.
OBJECTIVE
To evaluate the influence of age, sex, race, refractive error and optic disc topography on the sensitivity and specificity of scanning laser polarimetry (SLP) in the diagnosis of glaucoma.


METHODS
A total of 88 normal individuals and 95 glaucoma patients were included in this study. Glaucoma was defined on the basis of both optic nerve damage and visual field defects. Scanning laser polarimetry, optic disc topography, automated perimetry and refractometry were performed in all subjects. The sensitivity and specificity of SLP were assessed applying a previously calculated cut-off to a previously described linear discriminant function (LDF).


RESULTS
The sensitivity and specificity of SLP in the study population were 82% and 83%, respectively. Sensitivity and specificity were not affected by age, sex, race, average disc diameter or disc area. The sensitivity of SLP tended to be higher in myopes (93%) than in emmetropes (80%) and hyperopes (71%) (p = 0.08). Sensitivities were higher in individuals with cup areas > 0.96 mm(2) (89%), rim areas < or = 1.36 mm(2) (92%), and cup area/disc area ratios > 0.45 (89%) (p < 0.05). Stepwise logistic regression analysis indicated that the presence of a cup area > 0.96 mm(2) and a rim area < 1.36 mm(2) significantly increased the sensitivity of the LDF, whereas a cup area/disc area ratio < or = 0.45 significantly increased the specificity of the LDF.


CONCLUSIONS
The sensitivity and specificity of SLP may be influenced by refractive error and optic disc parameters that are affected by glaucomatous damage (cup area, rim area and cup area/disc area ratio). These parameters must be considered in studies evaluating the sensitivity and specificity of optic nerve/retinal nerve fibre layer imaging technologies.
Glaucoma Service, Department of Ophthalmology, University of Campinas, Campinas, Brazil. vp.costa@uol.com.br
Vital P
VP
Costa
Roberto
R
Lauande-Pimentel
Roberto A
RA
Fonseca
Leopoldo
L
Magacho
D000367:Age Factors; D001718:Birefringence; D003941:Diagnostic Techniques, Ophthalmological; D016002:Discriminant Analysis; D005260:Female; D005901:Glaucoma / Q000175:diagnosis* / Q000208:ethnology; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis; D044469:Racial Groups; D012030:Refractive Errors / Q000150:complications*; D012680:Sensitivity and Specificity; D012737:Sex Factors; D014786:Vision Disorders / Q000175:diagnosis; D058609:Visual Field Tests; D014794:Visual Fields