Monitoring the transition from corneal ulceration to healed scar using a Scheimpflug tomography–based densitometry

Purpose To compare corneal haze between active ulcer and healed scarring using a Scheimpflug densitometry. Materials and methods A prospective longitudinal study enrolled 30 patients (30 eyes) with ulcerative keratitis (UK). Each subject’s corneal optical density (COD) was measured with a Scheimpflug corneal densitometry, Pentacam® AXL (Oculus GmbH, Wetzlar, Germany), at the active ulcerative and complete scarring stage. The COD data were analyzed through distinct methods (inbuilt, sorted annular partitions, and ulcer-matching densitometric maps). We compared different CODs to select the better index for clinically monitoring the transition from corneal ulceration to healed scar. Results The CODs of the periphery ( P = 0.0024) and outside of the active ulcer ( P = 0.0002) significantly decreased after scarring. Partitioning the cornea into different depths and annular zones, the anterior layer, center layer, and the 2−6 mm annular zone had a more remarkable COD decrease after scar formation. The 3rd-sorted COD in the anterior layer revealed the highest area under the receiver-operating characteristic curves (0.709), in which 90% of subjects had COD reduction during the ulcer-to-scar transition. Conclusions Aside from subjective judgment based on clinical signs, the Scheimpflug tomography–based densitometry could provide objective and efficient monitoring of the corneal opacity evolution in UK patients. Because the 3rd-sorted annular COD is a better index than the inbuilt or mapping CODs in differentiating active ulcers from healed scars, this COD could be a clinically promising parameter to monitor the progression of UK patients.