Impact of digital enhancement on contrast ratio in internal limiting membrane peeling using the NGENUITY 3D visualisation system

Version 1.5 of the NGENUITY 3D digital visualisation system for eye surgery includes contrast enhancement and specific colour enhancement functions. Setting the enhancement functions too high can distort the images, causing deviation from their original appearance. Therefore, determining optimal settings is important. However, no studies have examined the relationship between these settings and surgical image visibility. This retrospective study investigated the relationship between the settings of these functions and the contrast ratio (CR) for internal limiting membrane (ILM) peeling. Consecutive patients who underwent vitrectomy using the NGENUITY Version 1.5 and ILM peeling at Juntendo University Urayasu Hospital were included. The retinal surface was stained with Brilliant Blue G (BBG), and ILM peeling was performed. The CR between the ILM-peeled and ILM-stained areas was measured. Contrast intensity (NGENUITY factor NGF) and Blue Boost (BB) (blue enhancement) were set from 0 to 5; the correlation between each setting and the CR was examined as well as the settings that exceeded a CR of 3, the standard for web accessibility. The CR between the ILM-peeled and ILM-stained areas in each setting was the main outcome measured. The 2 L included patients (21 eyes; 12 men and 9 women) had a mean age of 70.2 ± 7.7 years and a mean ocular axis length of 24.04 ± 1.17 mm. When BB was set to 0, the CR was 1.65 ± 0.20 at NGF0, which increased to 3.88 ± 0.72 at NGF 5. CR increased significantly with higher NGF values (p < 0.05). In contrast, when NGF was set to 0 with BB increased to 5, the CR was 1.74 ± 0.22, indicating that BB did not significantly affect the CR (p = 0.334). An NGF setting of 3 or higher consistently resulted in a CR exceeding 3, regardless of BB. For BBG-stained ILM peeling using the NGENUITY, a contrast enhancement setting of 3 or higher appeared to provide a sufficient CR regardless of BB, which is a key finding for future digitally assisted vitrectomy.