Effect of image exposure on corneal and lens densitometry measurements with Pentacam HR: an exploratory background-based analysis

To investigate whether image-level exposure variation affects corneal densitometry (CD) and lens densitometry (LD) measurements obtained with the Pentacam HR, and to explore whether background densitometry (BD) can serve as an image-based surrogate of exposure. This retrospective paired-measurement study included two routine preoperative Pentacam examinations obtained 2–3 months apart under standardized room illumination, without intentional alteration of ambient light. BD was measured in the non-tissue background above the corneal apex on Scheimpflug images. CD and LD parameters were compared between examinations and analyzed in relation to BD and changes in BD. Except for BD, corneal topographic and densitometry parameters did not differ significantly between the two examinations. No robust association was observed between CD and BD after sensitivity analysis and false-discovery-rate adjustment. By contrast, BD showed consistent positive associations with LD, and the change in LD was strongly associated with the change in BD. These findings suggest that BD may reflect image-level exposure variation in Scheimpflug densitometry, particularly for LD measurements. However, the analysis was exploratory and was intended to identify exposure-related trends rather than to propose a numerical adjustment; the interpretation requires validation in independent datasets and in eyes with corneal or lens pathology before clinical application.