Background Numerous studies have investigated the eyelid margin using confocal laser
scanning microscopy (CLSM) and have presented morphological alterations of the examined
structures, which were presumed to be Meibomian acini. However, recent data confirm
that these structures are the cross-sections of dermal papillae of the dermoepidermal
junction. This study aims to present the morphological appearance of Meibomian acini
examined by confocal laser scanning microscopy in comparison to dermal papillae, and
to reveal the corresponding patterns with specific histological sections. Methods
and Material Twenty healthy patients were examined with a CLSM device in vivo at the
marginal edge of the eyelid. Twenty-two samples of full-thickness eyelid wedges from
22 patients treated surgically with ectropion were collected, of which 11 freshly
excised samples were imaged on the incision surface with CLSM ex vivo and 11 eyelids
underwent conventional histological preparation. The represented structures on CLSM
images were compared to Meibomian acini on histological sections in terms of area,
longest and shortest diameter, as well as depth and density. Results On in vivo CLSM
images, Meibomian orifices, epidermal cells, and dermal connective tissue could be
identified, the latter in a cross-sectional view of the dermal papillae surrounded
by basal cells of the epidermis, forming reflective ring-like structures. All morphological
parameters of these structures differed from Meibomian acini measured on histological
sections. In contrast, the CLSM images of the incision surface showed acinar units
with the same morphology as the Meibomian acini seen in the histological images and
no statistically significant difference was found between the corresponding parameters.
Conclusion The morphological appearance of Meibomian acini differs from the structures
that were previously presumed as Meibomian glands on CLSM images. In vivo imaging
of Meibomian glands by commonly used in vivo CLSM cannot be performed.
