Wide-Field In Vivo Confocal Microscopy of Meibomian Gland Acini and Rete Ridges in the Eyelid Margin

Abstract

PurposeIn vivo confocal microscopy (IVCM) has been widely used to evaluate changes in the meibomian glands (MGs) in response to age and disease. This study examined the structures described as MGs using wide-field IVCM and laser scanning confocal microscopy (LSCM) in situ and characterized their spatial distribution and localization relevant to the eyelid margin.MethodsIVCM was performed on 30 subjects aged 18 to 38 to visualize structures in the eyelid margin. Size, shape, and distribution characteristics were measured, and individual frames were montaged into wide-field images. Structures observed on IVCM were then visualized using LSCM of whole-mount and cryosectioned cadaver eyelids stained with Nile red, mucin-1 (MUC1), laminin-5, and 4′,6-diamidine-2′-phenylindole dihydrochloride.ResultsThe size, distribution, and staining patterns of the reflective structures seen on IVCM did not correspond to the MGs in cadaver eyelids. Instead, staining profiles indicated that these structures corresponded to the rete ridges present at the dermal–epidermal junction. Wide-field imaging showed a densely populated field of rete ridges with distinct size and shape characteristics depending on their location relative to the meibomian orifices. A distal shift of the mucocutaneous junction (MCJ) was evident in some eyelids.ConclusionsIVCM is unable to visualize MGs in the human eyelid margin due to light attenuation at that tissue depth. LSCM confirms that these structures are rete ridges located at the dermal–epidermal junction. Alterations in the structure of the dermal–epidermal junction within the eyelid margin indicate a shifting of the MCJ and may impact tear film dynamics.

Changes in the tarsal conjunctiva viewed by in vivo confocal microscopy are associated with ocular symptoms and contact lens wear

“…Thus, the nature of the circularizing stimulus during ocular discomfort may be the consequence of the likely increased friction produced on the ocular surface of subjects with poor tear film quality. This would be consistent with the observation that aging, which is typically accompanied by a more flexible skin, has been associated with a decrease circularity of the papillae in the periorificial region of the Meibomian glands . Nonetheless, other factors, such as an inflammatory pathway, might be involved.…”

“…With regard to the rest of the parameters measured in the present study, no differences were found among groups. Although commonly misunderstanding the nature of the features typically seen, several previous workers have analysed confocal images from the eyelid. Villani et al .…”

“…In particular, the morphology of the eyelid can be microscopically visualized, and further analysed, using this technology . Several workers have used this technology to obtain images from the eyelids and observed circular and oval structures with a hyporeflective interior and a hyperreflective border . These structures were initially identified as Meibomian gland acini; however, the recent study of Zhou and Robertson provided evidence that these structures are instead rete ridges of the dermal‐epidermal junction.…”

“…In mucosal tissues, the equivalent union that joins the epithelium and lamina propria is commonly known as the epithelial‐lamina propria junction . Thus, the hyporeflective interior of the oval structures observed with confocal microscopy corresponds with the papilla lumen of the dermis or lamina propria, the hyperreflective border with the basal membrane of the epidermis or epithelium, and the area surrounding the papillae with the rete ridges of the epidermis or epithelium …”

“…17 This particular architecture of the skin and mucosal tissues enlarges the contact area between the dermis and epidermis as well as between the epithelium and lamina propria enhancing the metabolic exchange and reinforcing the adhesion between these two layers, among other functions. 18,19 Several studies, including those concerned with DED, 12 Meibomian gland dysfunction 13,14 and CL wear, 15,16 have reported morphological alterations of these structures, albeit that they were probably misinterpreted as Meibomian glands, 17 and this supports the potential of this technology to detect changes not commonly found using clinical tests. The possibility exists that changes in the epithelial-lamina propria junction of the conjunctiva may impact the ocular surface, producing effects on tear film dynamics for example.…”