Aditi Gupta1, Hala El-Rami1, Rasha Barham1, Alan Fleming2, Jano van Hemert2, Jennifer K Sun1,3, Paolo S Silva4,5,6, Lloyd Paul Aiello1,3. 1. Beetham Eye Institute, Joslin Diabetes Center, Boston, MA, USA. 2. Optos, plc, Dunfermline, Scotland, UK. 3. Department of Ophthalmology, Harvard Medical School, Boston, MA, USA. 4. Beetham Eye Institute, Joslin Diabetes Center, Boston, MA, USA. paoloantonio.silva@joslin.harvard.edu. 5. Department of Ophthalmology, Harvard Medical School, Boston, MA, USA. paoloantonio.silva@joslin.harvard.edu. 6. Teleophthalmology and Image Reading Center, Philippine Eye Research Institute, National Institutes of Health, University of the Philippines, Manila, Philippines. paoloantonio.silva@joslin.harvard.edu.
Abstract
BACKGROUND: To evaluate changes in image sharpness across ultrawide field (UWF) images and the effect of phase-plate adjustment on image contrast and extent of visible retinal area (VRA). METHODS: This was a single site evaluation of 200° UWF images acquired with phase-plate adjustment (California, Optos, plc) and without (200TX, Optos, plc). Images were acquired using standardized protocol. VRA was manually outlined on each image and quantified using customized software. Mean image sharpness was evaluated using an automated method within the full VRA of each image and within the peripheral region of the VRA. The VRA and image sharpness were evaluated and compared between the two devices. RESULTS: Twenty eyes of 10 healthy volunteers were evaluated. Devices with and without phase-plate adjustment produced a similar extent of VRA. Eye steering increased VRA in devices with and without phase-plate adjustment by 39.3% and 34.3%, respectively. Regardless of gaze direction, mean sharpness of the full VRA was reduced in peripheral area with or without phase-plate adjustment. Compared to images without phase-plate adjustment, use of phase-plate adjustment reduced the loss of peripheral image sharpness in all fields (-4.2 to -26.0%; p < 0.001 all fields). The sharpness of the peripheral area for on-axis images was 61.5% higher with phase-plate adjustment. CONCLUSIONS: The use of phase-plate adjustment does not alter the extent of VRA. However, for on-axis images the loss of sharpness in the periphery is 4.5-fold less with phase-plate adjustment, potentially reducing the need to steer images and improving lesion detection in these areas.
BACKGROUND: To evaluate changes in image sharpness across ultrawide field (UWF) images and the effect of phase-plate adjustment on image contrast and extent of visible retinal area (VRA). METHODS: This was a single site evaluation of 200° UWF images acquired with phase-plate adjustment (California, Optos, plc) and without (200TX, Optos, plc). Images were acquired using standardized protocol. VRA was manually outlined on each image and quantified using customized software. Mean image sharpness was evaluated using an automated method within the full VRA of each image and within the peripheral region of the VRA. The VRA and image sharpness were evaluated and compared between the two devices. RESULTS: Twenty eyes of 10 healthy volunteers were evaluated. Devices with and without phase-plate adjustment produced a similar extent of VRA. Eye steering increased VRA in devices with and without phase-plate adjustment by 39.3% and 34.3%, respectively. Regardless of gaze direction, mean sharpness of the full VRA was reduced in peripheral area with or without phase-plate adjustment. Compared to images without phase-plate adjustment, use of phase-plate adjustment reduced the loss of peripheral image sharpness in all fields (-4.2 to -26.0%; p < 0.001 all fields). The sharpness of the peripheral area for on-axis images was 61.5% higher with phase-plate adjustment. CONCLUSIONS: The use of phase-plate adjustment does not alter the extent of VRA. However, for on-axis images the loss of sharpness in the periphery is 4.5-fold less with phase-plate adjustment, potentially reducing the need to steer images and improving lesion detection in these areas.
Authors: Paolo S Silva; Jerry D Cavallerano; Jennifer K Sun; Jason Noble; Lloyd M Aiello; Lloyd Paul Aiello Journal: Am J Ophthalmol Date: 2012-05-23 Impact factor: 5.258
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Authors: Mohamed Ashraf; Abdulrahman Rageh; Michael Gilbert; Dorothy Tolls; Alan Fleming; Ahmed Souka; Samir El-Baha; Jerry D Cavallerano; Jennifer K Sun; Lloyd Paul Aiello; Paolo S Silva Journal: Transl Vis Sci Technol Date: 2021-06-01 Impact factor: 3.048