In vivo fluorescence mode confocal microscopy of subepithelial tissues in glaucoma filtering blebs

The miniaturization of confocal imaging technology has resulted in the development of a handheld confocal microscope probe capable of fluorescence mode imaging. Findings in the subepithelial tissues of glaucoma filtering blebs using this novel approach for proof of concept are described.

A fiberoptic confocal imaging probe using an illumination wavelength of 488 nm was applied to the bleb surface of 11 eyes after topical or subconjunctival administration of sodium fluorescein. The imaging plane was moved to the subepithelial region and multiple images from multiple bleb regions were captured at a resolution of 1,024 x 1,024 pixels per square inch.

High-quality images of the bleb wall structure, vasculature, and superficial sclera were obtained and demonstrated subcellular detail. Lateral resolution was between 1 and 1.5 microm and axial resolution was approximately 30 microm. Identifiable structures in the failing blebs included vasculature (including individual erythrocytes, pericytes, and vascular endothelium); microcystic structures; and cells within the Tenon's tissue, some of which resembled fibroblasts.

Fluorescence mode imaging of ocular subsurface detail is a viable and promising tool for assessment of wound healing and other processes in trabeculectomy blebs. The ability to image fluorophores creates the possibility of functional imaging.