Contact Specular Microscopy Reliably Images the Same Endothelial Location

Abstract

Purpose : Specular microscopes have been used since the late 1970s to diagnose, monitor, and analyze the corneal endothelium. Recently, Konan Medical has developed a contact wide-field slit-scanning specular microscope, the CellChek C (CCC), capable of in-vivo imaging of the entire cornea. This provides insight into the morphology of the peripheral endothelium that otherwise could not be imaged by commercially available microscopes. Previous research using earlier models of contact specular microscopes has shown that applanating the cornea creates unique undulations and concentric rings in the endothelium itself. It has been suggested that these undulations and posterior corneal rings (PCR) are static, and therefore could be used as landmarks to repeatedly find unique cells and track disease progression in the peripheral endothelium. We used the CCC to test this hypothesis and determine whether undulations or PCRs can be used to repeatedly image the same endothelial location.

Methods : We imaged 8 patients (12 eyes) without a history of corneal disease on two separate occasions, approximately 1 week apart. At the first visit, we identified undulations or PCRs to be used as landmarks; we attempted to re-image these landmarks at the second visit. Konan Medical software was used to calculate the difference in endothelial cell density (ECD) between visits. Unique endothelial cells in close proximity to each landmark were used to confirm we were imaging the same location.

Results : PCRs were used as landmarks in 6 patients (9 eyes), undulations were used in 2 patients (3 eyes). PCRs were repeatedly imaged in 8 of 9 eyes; undulations were not repeatedly identified. The mean ECD percent difference between the first and second visit was 2.93%, with a range of 0.32% to 6.57%. Figures 1 and 2 show the peripheral endothelium of the same patient a week apart.

Conclusions : Applanation of the cornea creates static landmarks that can be seen when using specular microscopy to image the corneal endothelium. These can be used to repeatedly locate specific endothelial locations over time, providing a means to track disease progression and the impact that pharmacological or surgical intervention may have on the endothelium.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Specular image of the peripheral endothelium. A PCR is present inferiorly out of the frame. The arrowhead indicates a unique endothelial cell.

 

Peripheral endothelium of the same patient after 1 week. The same cell is visible.