Quantitative comparisons of ultra-widefield images of model eye obtained with Optos® 200Tx and Optos® California

Abstract

Abstract Background To compare the quality of the ultra-widefield images acquired by Optos® 200Tx to those acquired by Optos® California. Methods Images of the posterior surface of a Gullstrand’s model eye obtained by Optos® 200Tx were compared to those obtained by Optos® California in terms of the angular field of view and the symmetry of the image, i.e., vertical and horizontal aspect ratios at the center (0°) and at the periphery (40° and 80°) in each direction. In addition, we compared the enlargement of the image on the posterior surface as the square ratio, and the differences in the contrasts. Results No significant differences were detected in the angular field of view between the two instruments. The aspect ratios showed that the Optos® California had more symmetrical images than the Optos® 200Tx at the center (0.98 vs 0.89, P < 0.01) and at the 40° periphery (0.93–1.04, △0.11 vs 0.79–1.01, △0.22) and 80° periphery (0.81–1.25, △0.44 vs 0.42–1.12, △0.70) in each direction. The amplitude of the square ratio of the Optos® California was smaller at 40° periphery (1.16–1.28, △0.12 vs 1.06–1.37, △0.31) and 80° periphery (2.12–2.46, △0.34 vs 1.14–3.29, △2.15). The contrast of the Optos® California images was significantly higher in the posterior pole (0.09 vs 0.12, P < 0.01), upper (0.07 vs 0.03, P < 0.01), and right (0.12 vs 0.07, P < 0.01) peripheries. Conclusion Optos® California can record equal angular widefield images to Optos® 200Tx and more symmetrical images with higher contrast in the posterior pole, upper and right peripheries.

Keywords

• Wide-field image
• Angle
• Contrast
• Scanning laser ophthalmoscope