Purchase this article with an account.
Srinivas R Sadda, Min Sagong, Jano van Hemert; Comparison of ultra-widefield Optos imaging with and without phase mask implementation. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1433.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Due to the spherical curvature of the eye, conventional ultra-widefield (UWF) images are sometimes affected by blurring in the far periphery when the center of the image is in focus. To compensate for this peripheral blurring, a phase mask has been implemented in the Optos California device. In this study, we compare far peripheral visualization utilizing the phase mask with standard widefield imaging.
Twenty one patients (39 eyes) from a tertiary academic retina practice with various diseases underwent UWF imaging using the Optos California with phase mask implementation and the Optos 200Tx without the phase mask. The images were obtained as a single, non-steered image centered on the macula and then transformed to stereographic projected images for assessment of far peripheral (beyond the equator) visualization. Transformed images were evaluated in a masked fashion by certified Doheny Image Reading Center graders. Grading was performed separately for each far peripheral quadrant (superior, inferior, nasal, temporal) for two parameters: (1) visualization of the full extent of the vasculature (terminus) and (2) sharpness of focus of the far peripheral vasculature [graded as excellent (80% or more of vessels), adequate (80% - 50%), or poor (50% or less)]. Results between the two devices were then compared.
The full extent of the far peripheral vasculature (to the terminus) could be seen more frequently with the phase mask in the superior (94.6% vs 5.4%, p<0.0001), nasal (91.9% vs 75.7%, p<0.0001), and temporal (56.8% vs 43.2%, p=0.048) quadrants. Inferiorly, there was no difference in the extent visualized due to lid/lash artifact, however, the vasculature was in sharper focus with the phase mask (excellent: 91.9% vs 83.8%, P = 0.019). The phase mask also yielded a sharper focus in the superior (excellent: 94.6% vs 24.3%, p <0.001) and nasal (excellent: 89.2% vs 75.7%, P = 0.016) quadrants.
The peripheral retina may be imaged effectively by widefield imaging devices with or without phase mask implementation. The phase mask, however, appears to improve visualization of far periphery (particularly superiorly), allowing the vasculature to be visualized to its full extent and in sharp focus. These findings may be of value in designing imaging protocols for assessment of the far periphery.
This PDF is available to Subscribers Only