Anatomy of the conjunctiva

elaborate discussion on the anatomy and physiology of the conjunctiva

1. ANATOMY AND PHYSIOLOGY OF THE CONJUNCTIVA Presented By Arundhati Hatikakoty Bachelor of Optometry 3 rd year Roll no- 302

2. Introduction Conjoin = to join So the name conjuctiva has been given to this mucous membrane owing to the fact that it joins the eyeball to the lids It is a translucent mucous membrane which lines the posterior surface of the eyelids and anterior aspect of the eyeball

3. The normal conjuctiva is P ink S mooth T hin Transparent There are normally large deep blood vesells that run vertically

4. Functions of conjunctiva T he conjunctiva helps lubricate the eye  by producing  mucus and   tears, although a smaller volume of  tears than the  lacrimal gland It also contributes to immune surveillance and helps to prevent the entrance of  microbes into the eye

5. Parts of the conjunctiva

6. Parts of the conjunctiva

7. Palpebral conjunctiva: It is richly vascular, extremely thin and strongly bounded to the tarsal plate

8. It lines the lids and is subdivided into

9. M arginal- Extends from the lid margin to about 2mm back of the lid upto the sulcus subtarsalis Actually a transitional zone between skin and the conjunctiva proper Lacrimal puncta open in the marginal zone

10. Tarsal- Thin, transparent and highly vascular Firmly adherent to the whole tarsal plate in the upper lid and only to half width of the tarsus in the lower lid The tarsal glands are seen through it as yellow streaks

11. Orbital- It lies loose between the tarsal plate and the fornix Orbital margin of the upper eyelid is loose and lies over the muller’s muscle

12. Bulbar conjunctiva- It is transparent and lies loose over the underlying structures and thus can be moved easily It is separated from the anterior sclera by episcleral tissue and tenon’s capsule

13. The average thickness is 33 microns It is also known as ocular conjunctiva It is further of two types

14. Limbal - A 3mm ridge of bulbar conjunctiva around the cornea is called limbal conjunctiva Strongly adherent to sclero -corneal junction Scleral- Covers the eyeball above the anterior sclera and hence known as scleral conjunctiva Thin, transparent & loosely attached to underlying sclera Separated from the sclera by episcleral vessels and Tenon’s capsule

15. Conjunctival fornix: It is thin, transparent , continuous circular cul-de-sac It is broken only on the medial side by caruncle and the plica semilunaris It joins the bulbar conjunctiva with the palpebral conjunctiva

16. It is further of four types

17. Superior Located at the level of superior orbital margin Extends from slightly upper border of the tarsal plate to a distance about 10mm from the upper limbus Here we can find the glands of Krause and Mullers’s muscle in the subconjunctival tissue

18. Inferior fornix Extends from slightly below the lower border of the lower tarsal plate to a distance about 8mm from the lower limbus Located near the inferior orbital margin Helps in maintaining the recess of the inferior fornix during movements of the lower lid

19. Lateral Small in size like a cul de sac Extends to just behind the equator of the eyeball It is 14mm from the lateral limbus and about 5mm from the lateral canthus Medial It is a shallow cul de sac in which lie the caruncle and plica seminlunaris dipped in pool of tears called as tear lake

20. HISTOLOGY OF THE CONJUNCTIVA

21. Structure of conjunctiva Histologically cornea consists of 3 layers

22. Epithelium The layers of epithelial cells in the conjunctiva vary from region to region and its different parts are Marginal conjunctiva- H ave 5 layers non keratinised stratified squamous type of epithelium Superficial layer- squamous cell Intermediate 3 layers- polyhedral cells Deepest layer- goblet cells Tarsal conjunctiva- Has 2 layer epithelium in the upper eyelid Superficial layer- cylindrical cells Deep layers- cubical cells Lower tarsal conjunctiva is made of 3-4 layers of cells like the cubical, polygonal, elongated wedge shaped and cone shaped cells

23. The Epithelium The Adenoid Layer The Fibrous Layer The Epithelium

24. Fornix and bulbar conjunctiva 3 layered epithelium Superficial layer- cylindrical ells Middle layer- polyhedral cells Deep layer- cuboidal cells Limbal conjunctiva 8-10 layers of stratified squamous epithelium Most superficial 1-2 layers- squamous cells Intermediate several layers- polygonal cells Basal layer- cylindrical or cubical cells

25. Cells Present In The Epithelium Goblet cells- Present between the epithelial cells in all regions of conjunctiva Melanocytes- Found in conjunctiva at limbus , fornix, crancule and at the site of entry of anterior ciliary vessels Langerhans cells- Present in all parts of conjunctiva Conjunctival associated lymphoid tissue ( CALT )- Consists of T and B lymphocytes

26. d. Mucosal associated lymphoid tissue(MALT) MALT of the gut and bronchi are also found in the conjunctiva

27. Adenoid layer Also called as lymphoid layer Consists of fine connective tissue reticulum in the meshes of which lie the lymphocytes Most developed in the fornices and ends at the subtarsal fold Develops after 2-3 months of life The Adenoid Layer

28. Fibrous layer Consists of a meshwork of collagenous and elastic fibres Thicker than the adenoid layer Except in the tarsal conjunctiva where it is very thin This layer consist vessels and nerves of the conjunctiva The adenoid layer and the fibrous layer are collectively called as substantia propia

29. The Epithelium The Adenoid Layer The Fibrous Layer The fibrous layer

30. Conjunctival glands

31. Goblet cells Round or oval in shape with an eccentric flat nucleus Unicellular mucous cells located abundantly w ithin the epithelium of all regions of conjunctiva These cells are formed from the deepest cells of the conjunctiva Once discharging their content- the mucin they are destroyed Density is more in children than adults More in the bulbar conjunctiva and inferior fornix

32. Henle’s glands Not true glands but folds of mucous membrane present in the palpebral conjunctiva These are tubular structures with lumina of 15-30 µm Glands of manz Found in limbal conjunctiva in animals

33. Glands of krause Microscopic glands that lie in the sub conjuctival tissue of the fornices These are about 40-42 in the upper fornix and about 6-8 in the lower fornix Glands of wolfring A lso called as the glands of Ciaccio These are microscopic glands present along the upper border of superior tarsus and lower border of inferior tarsus

34. Blood supply Arteries supplying the conjunctiva are derived from 3 sources. They are: Marginal arcade of the eyelid Peripheral arterial arcade of the eyelid Anterior ciliary artery The palpebral conjunctiva and the fornices are supplied by branches from the marginal and peripheral arcades of the artery

35. Bulbar conjunctiva is supplied by posterior conjunctival arteries and anterior conjunctival arteries

36. Venous drainage The veins from conjunctiva drain into the venous plexus of eyelids which in turn drain into the superior and inferior ophthalmic veins. A cicumcorneal zone of limbus drain into the anterior cilliary veins

37. Lymphatic drainage Lymphatics from the lateral side drain into the periauricular lymph nodes The lymphatics from the medial side drain the submandibular lymph nodes

38. Nerve supply A circumcorneal zone of the conjunctiva is supplied from the long ciliary nerves Rest of the conjunctiva is supplied by the branches from the lacrimal, infratrochlear , supratrochlear , supraorbital and the frontal nevers

39. Anatomy

40. References- AK Khurana , Anatomy and physiology of the eye 2 nd edition, page no- 306-372 AK Khurana , Comprehensive ophthalmology 4 th edition, page no- 51-54 AI Lens, Ocular Anatomy and Physiology, page 50-53 A . M. R. Agur , Grant's Atlas of Anatomy, page 650 https:// en.wikipedia.org/wiki/Conjunctiva#Function https://www.slideshare.net/pranaykumarshinde/conjunctiva-anatomy-and-physiology?qid=5cf7b98a-e6f5-4369-bccd-0b1168d7d77e&v=&b=& from_search=6

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