High-resolution optical coherence tomography for screening ocular surface tumors: Historical markers and future directions

Table 1 Gross histology of the lacrimal drainage system

Anterior segment structure	Histological appearance	Description
Lacrimal canaliculi	Stratified, non-keratinized squamous epithelium	Superior and inferior canals commencing from the nasal punctal orifices to the lacrimal sac
Lacrimal sac	Pseudostratified ciliated columnar epithelium and goblet cells	Dilated portion of the lacrimal fluid drainage system
Nasolacrimal duct	Pseudostratified ciliated columnar epithelium	Drains tear fluid toward the inferior meatus of the nasal cavity

Table 2 Gross histology of the external ocular tunic

Histologic landmarks	Structural anatomy	Clinical anatomy
Episclera	Loose fibroelastic tissue layer overlying Tenon's capsule	Vascularized portion of sclera
Tenon’s capsule	Smooth muscle fiber and collagenous fascia	Transition zone from episclera to sclera
Stroma	Interlacing network of type 1 collagen and elastic fibers, oriented without parallelism.	Dense portion of sclera
Suprachoroidal lamina	Contains fibroblasts and melanocytes	Thin fibrous connective tissue between sclera and choroid
Scleral endothelium	Simple squamous epithelium	Covers deep suprachoroidal lamina at the limbus
Limbus	Scleral-corneal junction. Transition of scleral to corneal collagen bundles	Area of contact between conjunctival stroma and Tenon's capsule. Limbal stem cells (unipotent to superficial corneal layers) at palisades of Vogt