HRT Glaucoma Module
A Powerful Predictor of Change
- Validated by OHTS to predict structural change
- Progression analysis validated with 10 year’s of patient data
- Optic disc analysis outperforms expert interpretation
- Large, ethnic-selectable databases
- Asymmetry analysis
- Upgradeable platform
- Network ready
The Heidelberg Retina Tomograph (HRT) is a proven, essential tool for detecting and managing glaucoma, especially for assisting in the identification of pre-perimetric disease and tracking progression. The Ancillary Study to the Ocular Hypertension Treatment Study (OHTS) demonstrated that optic disc analysis detected glaucoma conversion in 55% of cases, before any detectable loss of visual function. The HRT has proved to be a robust predictor of glaucoma. OHTS also concluded that the HRT recognized temporal superior defects which later developed into confirmed glaucoma in 40% of cases - looking only at baseline measurements - then confirmed the diagnosis with an average of 5 years of follow-up. Equally impressive was that 93% of all HRT cases flagged as within normal limits at baseline remained within normal limits during the same time period.
Figure A
The Ancillary Study to the Ocular Hypertension Treatment Study (OHTS) demonstrated that the HRT could outperform visual fields and expert opinion in predicting structural change in glaucoma.
Figure B
The Moorfields Regression Analysis (MRA) has remained a robust indicator of structural change over 15 years and more than 400 clinical papers.
24 ms Scanning and TruTrack™ Image Alignment
The recent discovery of hidden artifacts within time-domain OCT scans may explain why time-domain OCT performed so poorly in a separate, but similar study, where baseline predictive values for corneal thickness outperformed OCT with an average of 5 years of follow-up.
One explanation for the difference in glaucoma predictive power is the HRT’s incredible scan speed. Single tomographic slices are captured in just 24 milliseconds (compared to the fastest time-domain OCT slices captured at 368 milliseconds). Since constant involuntary eye movements occur within 30 - 50 milliseconds, and larger movements due to fixation problems can be 150 milliseconds or greater, time-domain OCT may be highly susceptible to motion artifact.
HRT combines the advantage of speed with the power of Heidelberg Engineering’s TruTrack™ image alignment software to deliver unmatched performance and clinical utility. TruTrack™ works in the background, tracking over 500 points on each image, enabling follow-up scans to be precisely aligned to baseline for detecting small changes reliably.
The first long-term results using time-domain OCT showed that pachymetry may be a better predictor of glaucoma. Stereo fundus photos had a higher predictive value than either OCT or corneal thickness.
Time-domain OCT cannot track location due to slow scan time and the impact of motion artifact.