Detecting early glaucoma by assessment of retinal nerve fiber layer thickness and visual function

PURPOSE. To compare the abilities of scanning laser polarimetry (SLP), opti cal coherence tomography (OCT), short-wavelength automated perimetry (SWAP) , and frequency-doubling technology (FDT) perimetry to discriminate between healthy eyes and those with early glaucoma, classified based on standard a utomated perimetry (SAP) and optic disc appearance. To determine the agreem ent among instruments for classifying eyes as glaucomatous. METHODS. One eye of each of 94 subjects was included. Healthy eyes (n = 38) had both normal-appearing optic discs and normal SAP results. Glaucoma by SAP (n = 42) required a repeatable abnormal result (glaucoma hemifield test [GHT] or corrected pattern standard deviation [CPSD] outside normal limits ). Glaucoma by disc appearance (n = 51) was based on masked stereoscopic ph otograph evaluation. Receiver operating characteristic (ROC) curve areas, s ensitivities, and specificities were calculated for each instrument separat ely for each diagnosis. RESULTS. The largest area under the ROC curve was found for OCT inferior qu adrant thickness (0.91 for diagnosis based on SAP, 0.89 for diagnosis based on disc appearance), followed by the FDT number of total deviation plot po ints of less than or equal to5% (0.88 and 0.87, respectively), SLP linear d iscriminant function (0.79 and 0.81, respectively), and SWAP PSD (0.78 and 0.76, respectively). For diagnosis based on SAP, the ROC curve area was sig nificantly larger for OCT than for SLP and SWAP. For diagnosis based on dis c appearance, the ROC curve area was significantly larger for OCT than for SWAP. For both diagnostic criteria, at specificities of greater than or equ al to 90% and greater than or equal to 70%, the most sensitive OCT paramete r was more sensitive than the most sensitive SWAP and SLP parameters. For d iagnosis based on SAP, the most sensitive FDT parameter was more sensitive than the most sensitive SLP parameter at specificities of greater than or e qual to 90% and greater than or equal to 70% and was more sensitive than th e most sensitive SWAP parameter at specificity of greater than or equal to 70%. For diagnosis based on disc appearance at specificity of greater than or equal to 90%, the most sensitive FDT parameter was more sensitive than t he most sensitive SWAP and SLP parameters. At specificity greater than or e qual to 90%, agreement among instruments for classifying eyes as glaucomato us was poor. CONCLUSIONS. In general, areas under the ROC curve were largest (although n ot always significantly so) for OCT parameters, followed by FDT, SLP, and S WAP, regardless of the definition of glaucoma used. The most sensitive OCT and FDT parameters tended to be more sensitive than the most sensitive SWAP and SLP parameters at the specificities investigated, regardless of diagno stic criteria.