Conjunctiva

Conjunctiva
The upper half of a sagittal section through the front of the eyeball. (Label for 'Conjunctiva' visible at center-left)
Horizontal section of the eyeball. (Conjunctiva labeled at upper left)
Details
Part of	Eye
Artery	lacrimal artery, anterior ciliary arteries
Nerve	supratrochlear nerve
Identifiers
Latin	tunica conjunctiva
MeSH	D003228
TA98	A15.2.07.047
TA2	6836
FMA	59011
Anatomical terminology [edit on Wikidata]

In the

Structure

The conjunctiva is typically divided into three parts:

Blood supply

Blood to the bulbar conjunctiva is primarily derived from the ophthalmic artery. The blood supply to the palpebral conjunctiva (the eyelid) is derived from the external carotid artery. However, the circulations of the bulbar conjunctiva and palpebral conjunctiva are linked, so both bulbar conjunctival and palpebral conjunctival vessels are supplied by both the ophthalmic artery and the external carotid artery, to varying extents.^[4]

Nerve supply

Sensory innervation of the conjunctiva is divided into four parts:^[5]

Microanatomy

The conjunctiva consists of unkeratinized, both stratified squamous and stratified columnar epithelium, with interspersed

The conjunctiva helps lubricate the eye by producing mucus and tears, although a smaller volume of tears than the lacrimal gland.^[7] It also contributes to

Clinical significance

Disorders of the conjunctiva and

• The conjunctival microvascular hemodynamics are affected by diabetic retinopathy (DR), hence can be useful for DR diagnosis and monitoring,^[8] and discriminating stages of DR.^[9]
• hypoxia,^[10] increased average blood vessel diameter, and capillary loss.^[11][12][13]
• micro-haemorrhages.^[14][15][16]
• Hypertension is associated with an increase in the tortuosity of bulbar conjunctival blood vessels and capillary and arteriole loss.^[17][18]
• Carotid artery occlusion is associated with slower conjunctival blood flow and apparent capillary loss.^[4]
• With age, the conjunctiva can stretch and loosen from the underlying sclera, leading to the formation of conjunctival folds, a condition known as conjunctivochalasis.^[19][20]
• The conjunctiva can be affected by tumors which can be benign, pre-malignant or malignant.^[21]
• Leptospirosis, an infection with Leptospira, can cause conjunctival suffusion, which is characterized by chemosis, and redness without exudates.

Bulbar conjunctival microvasculature

Vessel morphology

The bulbar conjunctival

The bulbar conjunctival microvessels are typically imaged with a high-magnification slit lamp with green filters.^[25][26][27] With such high-magnification imaging systems, it is possible to see groups of individual red blood cells flowing in vivo.^[25] Fundus cameras may also be used for low-magnification wide field-of-view imaging of the bulbar conjunctival microvasculature. Modified fundus cameras have been used to measure conjunctival blood flow ^[28] and to measure blood oxygen saturation.^[24] Fluorescein angiography has been used to study the blood flow of the bulbar conjunctiva and to differentiate the bulbar conjunctival and episcleral microcirculation.^[29][30][31]

Vasodilation

The bulbar conjunctival microvasculature is known to dilate in response to several stimuli and external conditions, including allergens (e.g. pollen),^[32] temperature,^[33] time-of-day,^[33] contact-lens wear,^[13] and acute mild hypoxia.^[24] Bulbar conjunctival vasodilation has also been shown to correlate changes in emotional state.^[34]

Type 2 diabetes is associated with an increase in average bulbar conjunctival vessel diameter and capillary loss.

• Conjunctivitis (pink-eye)
• Conjunctivochalasis
• Dry eye
• Pinguecula
• Pterygium
• Rougine
• Subconjunctival hemorrhage
• Diabetes
• Sickle-cell disease
• Slit lamp

Additional images

• 
  Sagittal section through the upper eyelid.
• 
  Extrinsic eye muscle. Nerves of orbita. Deep dissection.

References