For imaging the posterior segment and the optic nerve, optometrists have many options. When evaluating patients for glaucoma, for instance, doctors can turn to technologies such as spectral domain OCT (SD-OCT), scanning laser polarimetry (GDx, Laser Diagnostic Technologies) or Heidelberg Retinal Tomograph (HRT) scanning laser ophthalmoscopy. And, according to new research, it turns out whichever one you select for your office is about as good as the other two.
Researchers out of Finland reviewed 6,060 eyes of 3,039 subjects with the GDx, HRT and SD-OCT. They found that specificity rates for all devices were high and relatively close. The SD-OCT was 90% specific, the GDx was 88% specific and the HRT was 96% specific. Post-test probabilities of glaucoma after positive imaging finding with each of these methods were 6%, 5% and 7%, respectively. Retinal nerve fiber layer (RNFL) and macular ganglion cell layer and inner plexiform layer analysis were measured and combined with each device, resulting in specificities of 95% and 92%, respectively.
The participants in this study were between 45 and 49 years old and were associated with the Northern Finland Birth Cohort Eye Study. The performance of the automated classification of the imaging devices was assessed using a clinical glaucoma diagnosis as reference; that is, the ‘2 out of 3’ rule based on the evaluation of optic nerve head and RNFL photographs and visual fields. Glaucomatous damage was found in 43 eyes of 33 subjects.
|Karvonen E, Stoor K, Luodonpää M, et al. Diagnostic performance of modern imaging instruments in glaucoma screening. Br J Ophthalmol. January 16, 2020 [Epub ahead of print].|