Relationship between the mean deviation of the visuald field (Humphrey) and the analysis of the retinal fiber layer thickness of the optical coherence tomography (Stratus OCT) for moderates and severes glaucomatous eyes

Abstract

Purpose: To evaluate the capacity of optical coherence tomography Stratus (OCT) and its role in discriminating moderate versus severe glaucoma by the study of retinal nerve fiber layer thickness.

Methods: This comparative study includes sixty-six glaucomatous eyes (42 moderates and 24 severes). Eyes were separated in two groups according to Hoddap classification, based on the visual field white-white SITA Standard (Swedish Interactive Threshold Algorithms) 24.2. The peri-papillar retinal nerve fiber layer thickness was measured by the stratus OCT using the the protocol Fast RFNL Thickness. The studied Oct parameters used were the global average thickness (global mean), and the thickness of the retinal fiber layers on the four meridian lines. The OCT parameters were then compared with the mean deviation (MD) of the visual field.

Results: The global average thickness of the retinal nerve fiber layer is respectively 64.73 µm +/- 9.87, 54.14 +/- 9,98 for the moderate and the severe glaucomatous eyes with a significant difference of p=0.0007. The thickness of the retinal fiber layers on the four meridian quadrants were found significantly different between the two groups (p=0.05) for the temporal, superior and inferior meridian. The global mean and the inferior and temporal meridian lines showed the most important areas under the ROC curve (respectively 0.766 0.785 and 0.780) for the moderate glaucoma against the severe ones. The threshold of 44µm for the temporal quadrant has an ability of discrimination of 76% of specificity and sensibility.

Conclusions: OCT of optic nerve fiber layer is a very interesting discrimination tool for moderate to severe glaucoma. It gives estimation of nerve fiber layer thickness at which the disease risks to progress to a more severe stage. It complements well the visual field and combined to it, helps to the evaluation of the severity of glaucoma and its management even for advanced cases.

Keywords: 642 perimetry • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 627 optic disc