Abstract
Purpose: :
To investigate the sensitivity of Topographic Change Analysis (TCA) from Scanning Laser Tomography for the detection of small amounts of neuroretinal rim loss during long term follow-up of patients with chronic open angle glaucoma compared to repeated digital planimetry measurements.
Methods: :
Thirty patients with an annual follow-up of at least 10 years and evidence of progressive glaucomatous damage were included in the study. All patients were members of the Erlangen Glaucoma Registry and received a detailed standardized glaucoma examination including Scanning Laser Tomography and optic disc photography. Progressive glaucomatous damage was defined as visible neuroretinal rim loss if the first slide and the most recent slide of the optic nerve head from the same eye were judged by two experienced investigators. Photographs were used for performance of digital planimetry and results were compared with TCA. Progression based on digital planimetry was determined if 95% CI from the follow-up image does not overlap the 95% CI from the baseline image. Progression based on TCA was determined as reproducible occurrence of more than four adjacent red coloured super pixels located over the neuroretinal rim. Gap between baseline and first evidence of progression were compared between different methods.
Results: :
Mean observation time until evidence of morphologic progression was 5.0±3.1 years for digital planimetry, 5.3±3.2 years for qualitative assessment of simultaneously projected optic disc slides and 5.9±3.3 years for TCA. Time gap for individual cases differed from 5 years before to 7 years after detection from qualitative optic disc evaluation for TCA and from 4 years before to 8 years after detection from qualitative evaluation for digital planimetry.
Conclusions: :
Overall digital planimetry and TCA revealed comparable results but a difference of several years until first evidence of morphologic progression may occur in some individuals. Digital planimetry is much more time consuming but may be slightly more sensitive for small changes.
Keywords: optic disc • imaging/image analysis: clinical