Low-cost optical coherence tomography can compete with standard instruments
A novel, low-cost optical coherence tomography (OCT) system produces images with adequate resolution that can be used for clinical diagnosis, according to a recent study.
While future trials will be required before clinical rollout, “the introduction of a low-cost OCT device offers great promise in improving access to retinal screening and early disease detection, especially in underserved areas and for vulnerable minority populations,” said researchers, noting that the performance of the new OCT device is comparable to the current commercial systems but is available for only a fraction of the cost.
The OCT device was tested for the first time on 120 eyes of 60 patients (36 females), half of whom had retinal disease (mean age, 70.4 years). For a field of view of 6.6 mm in the X and Y directions, the new system showed an axial resolution of 8.0 µm, lateral resolution of 19.6 µm and an imaging depth of 2.7 mm. [Transl Vis Sci Techn 2019;doi:10.1167/tvst.8.3.61]
Compared with the standard Heidelberg Spectralis OCT system, the low-cost alternative produced images with comparably resolved relevant layers of the retina. While the Heidelberg images had stronger retina signals, due to a higher incident optical power, the images from the low-cost system had lower intensity.
On the other hand, images from the new system had lower and more uniform background noise variance relative to images drawn from the standard OCT.
The mean contrast-to-noise ratio (CNR) of the low-cost OCT images, regardless of the presence of pathology, was 1.592±0.021. That for the Heidelberg images was 1.687±0.027. Paired t-tests showed that the between-system difference of 5.6 percent was statistically significant (p<0.0001).
The same was true for differences between the two OCT systems when analysis was restricted to eyes with (5.3 percent; p=0.0004) or without (6.0 percent; p<0.0001) pathologies.
“Although the mean CNR values of the two instruments are statistically distinct, a 5.6-percent difference is not expected to have a practical impact on most diagnostic applications, especially considering that the low-cost OCT comes at a fraction of the cost of the higher performance system,” said researchers.
“Notably, the CNR standard deviation across images was 0.3 and 0.4 for the low-cost and Spectralis systems, respectively, indicating that patient-to-patient variability exceeds the small difference in the CNR metric,” they added.
Through different cost-reduction design and engineering choices, the new OCT system needed only $5,037 to manufacture. A tradeoff of this is a weaker superluminescent diode, which demonstrated power fluctuations during imaging. According to researchers, this issue is expected to be addressed in future iterations of the device.
Moreover, the costs outlined in the present study only consider manufacturing, they pointed out. Further developments of the device, such as the addition of a fundus camera and more scanning patterns using the microelectromechanical system, will contribute more incurred costs.
“The costs of commercial development, regulatory approval and quality manufacturing processes will result in a higher final retail price of the low-cost system; however, this will also be offset by economies of scale in mass producing larger numbers of instruments,” they said.