Abstract
Purpose: :
To assess the capability of OCT Cirrus new software of progression to identify retinal nerve fiber layer (RNFL) changes in glaucoma and ocular hypertension.
Methods: :
This prospective study enrolled 181 eyes for a mean follow-up of 12 months. Patients were examined with Humphrey visual fields and OCT Cirrus (Zeiss-Meditec) at base line. OCT images and visual fields were performed every 3 to 6 months. Only good quality images (signal strength was = > 6 and no artifacts) were included in the study. Progression analysis was performed with Cirrus new software Guided Progression Analysis (GPA). This is a combined event and trend analysis that accounts for individual measurement variability and compares follow up images with two base line images. Main outcome measures were: RNFLT (RNFL Thickness) Map Progression, RNFLT Profiles Progression, Average RNFLT Progression and trend analysis of average, superior and inferior RNFLT. All may result as no progression, possible progression, or probable progression.
Results: :
Mean number of OCT images was 3.49. A total of 38 eyes (21%) showed possible or probable progression in at least one index. The number of indices with progression varied: 1 in 13 eyes, 2 in 9 eyes, 3 in 5 eyes, 4 in 4 cases, 5 in 5 cases and only 2 eyes showed changes in all parameters. The RNFLT Map and the Average RNFLT were the indices that showed progression with highest frequency. No relation was found between baseline RNFLT and the different progression parameters (p>0,05). Three of the six indices were related to the number of scans and 4 indices were related with the time between the first and last visit. The number of eyes with more indices showing progression did not increase with follow-up time (p=0.35) or the number of scans (p=0.43).
Conclusions: :
GPA for Cirrus identified progression after two baseline images and one follow up images. Indices based on event analysis showed progression more frequently than those based on trend analysis. Detection of progression was not related to baseline RNFLT.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer • optic nerve