Abstract
Purpose::
To compare the abilities of GDxVCC polarimeter and the new tool OCT/SLO on the discrimination between healthy and early perimetric glaucomatous eyes based to retinal nerve fiber layer (RNFL) thickness analysis. To determine a significative conversion factor on the different measurement methods.
Methods::
36 eyes of 36 patients (Group 1: 16 eyes of 16 healthy patients and Group 2: 20 eyes of 20 patients with early glaucoma with mean deviation - 3.7 +/- 3.0 dB and pattern standard deviation 4.5 +/- 2.7 dB) underwent imaging by the scanning laser polarimeter (GDxVCC; Zeiss) and OCT/SLO (OTI) RNFL scanning protocol. Results were analyzed with statistical T Student method. Correlation and regression tests were applied to evaluate and compare data.
Results::
Group 1 TSNIT Avg (Temporal-Superior-Nasal-Inferior-Temporal average) thickness was 61.15 µm with GDxVCC and 127.53 µm with OCT/SLO, in Group 2 48.6 µm with GDxVCC and 106.9 µm with OCT/SLO. The Superior average was respectively 78.27 µm with GDxVCC and 137.73 µm with OCT/SLO in Group 1, whereas Group 2 56.6 µm with GDxVCC and 128.6 µm with OCT/SLO. The Inferior average in Group 1 was 72.48 µm with GDxVCC and 145.93 µm with OCT/SLO, in Group 2 56.6 µm with GDxVCC and 112.4 µm with OCT/SLO. A statistically significant difference (p<0.05) on healthy and glaucomatous eyes RNFL thickness was obtained with two instruments; positive correlation on regression line were identified between GDxVCC and OCT/SLO data.
Conclusions::
Our analysis showed the discriminative ability on early glaucoma detection of both GDxVCC and new OCT/SLO OTI instruments. TSNIT, Superior and Inferior RNFL Thickness variation on GDxVCC and OCT/SLO were significantly correlated. Trasversal-layer-scanning protocol on new OCT/SLO demonstrate comparable clinical efficacy as GDxVCC. A conversion factor has actually to be verified on a wider casuistry. Further studies will be applied on advanced glaucoma stage for the detection of RNFL damage.
Keywords: nerve fiber layer • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • perimetry