In Vivo Laser Scanning Confocal Microscopy of the Ocular Surface in Glaucoma

Abstract

Over the past decade, knowledge about the ocular surface in glaucoma has significantly increased through the use of in vivo laser scanning confocal microscopy (LSCM). This in vivo imaging method can show modifications at the cellular level induced by anti-glaucoma drugs on ocular surface structures and adnexa in the eye. High-quality images of the conjunctiva, cornea, limbus, meibomian glands, and lymphoid structures during therapy can be obtained. In addition, LSCM opened new fields of research on the patho-physiology of aqueous humor (AH) hydrodynamics in untreated, and in medically or surgically treated glaucomatous patients. In these conditions, an enhancement of the trans-scleral AH outflow contributed to clarification of the mechanism of action of different anti-glaucoma medications and surgical approaches. Finally, the use of LSCM represented a huge advance in evaluation of bleb functionality after filtration surgery, defining the hallmarks of AH filtration through the bleb-wall and distinguishing functional from nonfunctional blebs. Thus, signs seen with LSCM may anticipate clinical failure, guiding the clinician in planning the appropriate timing of the various steps in bleb management. In this review we summarize the current knowledge about in vivo LSCM of the ocular surface in glaucoma.

Three-dimensional Laser Scanning Confocal Analysis of Conjunctival Microcysts in Glaucomatous Patients Before and After Trabeculectomy

“…At baseline, in the enface view (Figure 1), CEM appeared as dark structures, round or oval shaped, located below the epithelium and similar to those previously described in medically-treated glaucomatous patients (4,7,8). …”

“…For these reasons LSCM is currently the most frequently used confocal microscope in ophthalmology for both research purposes and in daily clinical practice. The interest to study the modification of conjunctival surface in glaucomatous eye was focused on the presence of epithelial microcysts (CEM) that is typical but not limited to eyes that underwent filtration surgery, since they were described also in untreated ocular hypertension (OH), in medically-treated open glaucoma and also in bleb-less surgical procedures (4)(5)(6)(7)(8)(9)(10).…”

In Vivo Scanning Laser Confocal Microscopy of Conjunctival Goblet Cells in Medically-controlled Glaucoma

“…Twelve high-quality images, without motion blur or compression lines, were selected from the three conjunctival sectors (superior nasal, superior central, superior temporal) to calculate the number of GCs using Cell Count Software (Heidelberg Engineering GmbH) in manual mode. This definition was adopted taking into account reference images and the morphological characterization, in vivo 32: 437-443 (2018) as previously reported in the literature (21)(22)(23). The total confocal examination session lasted 10 min and none of the patients experienced particular complications at the end of the session.…”

Evaluation of the conjuntival blebs using spectral domain optical coherence tomography after glaucoma surgery

“…LSCM was used to study the conjunctiva before and after different surgical and medical therapies for glaucoma to analyze AH outflow pathways modifications. [16][17][18][19] In filtration surgery, LSCM proved valuable in assessing the drainage capability of conjunctival blebs by assessing microcysts density and area within the epithelium, and the collagen deposition within the stroma. [11][12][13][14] While LSCM permits a microscopic analysis, with the advantage of analyzing tissue at a cellular level, AS-OCT allows a macroscopic analysis, useful in classifying blebs according to their morphology.…”