Abstract
Purpose: :
The aim of this paper is to study the diagnostic performance of Confocal Laser Ophthalmoscopy (CLO) in glaucomatous eyes with Standard Automated Perimetry (SAP) asymmetric hemifield defects (HF).
Methods: :
Primary open angle glaucoma (POAG) patients had their visual field (VF) examinations prospectively evaluated. Asymmetric VF examinations were defined by the presence of a cluster of at least 3 points with p < 0.5% in the patter deviation graph of the Humphrey printout, and the absence of any point with p≤ 5% in the opposite HF in the most reliable VF examination. The damaged HFs were classified as affected (AHF) and the opposite as "normal" (NHF). Age-matched subjects with ophthalmoscopically normal optic discs and normal VF printouts were used for comparison (control group). In order to assess a continuous variable for each superior and inferior HF, the arithmetic average was calculated using the values of all points in the pattern deviation (PD) graph in each HF. The values obtained were called pattern deviation indexes (PDI).Similarly, the values of the superior and inferior pattern deviation graphs were calculated in the control group. The following CLO (HRT 3.0 GPS protocol) parameters were used for analysis: Disc Size, Rim/Disc Area (RDA), Glaucoma Probability Score (GPS), Mean RNFL Thickness (RNFL), and Cup Area (CA). For each parameter, superior and inferior indexes were calculated. Pearson's Correlation and the Area Under Curve of the Receiver Operator Characteristic (AUC ROC) of CLO parameters were analyzed statistically.
Results: :
Twenty-five (25) glaucomatous eyes and twenty-four (24) normal subjects were included. The groups did not differ in terms of age, ethnicity and disc size. NHF of glaucomatous eyes showed significant difference of their PDI when compared to HF of normal individuals (p=0.036). The CLO parameters showed significant and moderate correlation with the PDI of the corresponding HFs. CLO diagnostic ability for the AHFs of glaucomatous eyes was higher using RNFL thickness (AROC = 0.88) followed by the Rim/Disc Area (AROC =0.86). For the NHFs, the diagnostic ability decreased significantly for all parameters.
Conclusions: :
The CLO diagnostic ability of all parameters decreased in NHFs of glaucomatous eyes. This study proposes a reliable model of pre-perimetric visual field defect which could be used to study the diagnostic ability of new imaging technologies.
Keywords: imaging/image analysis: clinical