- PATHOLOGIC RESPONSES OF THE CONJUNCTIVA
Some features of conjunctival disorders seen in slit lamp or during examination with side illumination may be specific for various types of conjunctival diorders. They include:
Conjunctival hyperemia – It is produced by dilation of blood vessels and is classified as superficial (Fig.1) (dilation of conjunctival vessels seen as a reddish flush of the conjunctiva) and deep (dilation of ciliary of episcleral vessels seen as a bluish subconjunctival flush). Superficial hyperemia disappears after instillation of phenylephrine drops or touching with glass rod. The extent and location of conjunctival hyperemia depends on underlying pathology. Diffuse, superficial hyperemia of both the bulbar and tarsal conjunctivae is typical of conjunctivitis (Fig.2). It is usually the most pronounced in viral conjunctivitis. Circumcorneal conjunctival hyperemia of deep vessels that extend 1 to 3 mm out from the limbus, without significant hyperemia of the bulbar superficial conjunctival vessels is seen in iritis and acute glaucoma. Diffuse or circumscribed areas of both superficial and deep hyperemia involving 20 to 100% of the bulbar conjunctiva without hyperemia of the tarsal conjunctiva is typical of episcleritis and scleritis.
Fig. 1 Superficial conjunctival hyperemia in bacterial conjunctivitis
Fig. 2 Significant conjunctival hyperemia in epidemic keratoconjunctivitis
Conjuntival vessels tortuosity – General tortuosity of all, small conjunctival vessels without any inflammatory signs is typical feature of Fabry disease, ataxia telangiectasia (LouisBar syndrome), mucolipidosis I and blood hyperviscosity disorders. (Fig.3) Dilated large vessels are seen in Sturge-Weber syndrome and especially in carotid-cavernous sinus fistula and dural shunts (corkscrew, aterialized venous vessels). (Fig. 4 and 5) Segmental dilatation and tortuosity of vessels can be seen as a secondary signs of various conjunctival disorders including melanocytic lesions, choristomas, epithelial cysts, pterygium and pinguecula.
Fig. 3 Vascular tortuosity in ataxia telangiectasia
Fig. 4 Dilated large conjunctival vessels in Sturge-Weber syndrome
Fig. 5 Corkscrew, aterialized venous vessels in carotid-cavernous sinus fistula
Telangiectasies – These vascular lesions are segmental alterations of the conjunctival vessels structure with aneurysmal dilatation. They are typical signs of Goldenberg syndrome (galactosialidosis), Rendu-Osler-Weber syndrome and ataxia telangiectasia (Louis Barr syndrome).(Fig. 6) Very rarely they can be found in lymphangiectasia. Conjunctival telangiectasies have been also described in morphea coup de saber syndrome (congenital linear groove in scalp or forehead skin spreading to the lids and eye). (1)
Fig. 6 Conjunctival telangiectasia in ataxia telangiectasia
Conjunctival haemorrhages – Can be found in conjunctivitis (the most frequently in viral – picornaviral and herpetic infections), after trauma, rise of central venous pressure (after the birth, after the activity involving Valsalva type maneuvers, after a seizures) and disorders with thrombocytopenia.
Edema – It is caused by edematous thickening of conjunctiva. Gross edema with ballooning of the conjunctiva often leading to its prolapse between the eyelids is known as chemosis. It can be associated with allergy, trauma (including surgery), acute infections and orbital inflammations.
Papillae - They present as elevated, polygonal, hyperemic areas separated by pale channels with central vessel erupting into a spoke-like pattern. The connective tissue septa that anchor the epithelium to the deeper collagenous tissue limits the size of papilla to less than 1mm. (Fig. 7) Papillae are non specific sign occurring in any kind of inflammation (mainly in bacterial and allergic).
Fig. 7 Conjunctival papillae in bacterial conjunctivitis
Giant papillae - They are formed by the disruption of the connective tissue septa and coalescence of 2-4 papillae. Its size is greater than 1 mm. (Fig. 8) They are usually manifestation of ocular allergy not infections, typically found in vernal conjunctivitis, atopic keratoconjunctivitis, and giant papillary conjunctivitis (reaction to contact lenses, sutures, prostheses).
Fig. 8 Giant papillae in giant papillary conjunctivitis
Follicles - There are numerous, smooth, yellowish elevation of the conjunctiva, 2-4 mm of diameter, similar to small grain of rice, with no vessels inside them. (Fig. 9) Follicles represent hyperplasia of subconjuntival lymphoid tissue. They are common presentation of viral (acute inflammation lasting less than 3 weeks), chlamydial conjunctivitis (chronic inflammation with exacerbation lasting more than 3 weeks) and can be found in benign lymphoid hyperplasia (folliculosis), Parinaud’s oculoglandular syndrome and in toxic reactions (medications, molluscum contagiosum).
Fig. 9 Follicles in inclusion conjunctivitis in adolescent
Membranes or pseudomembranes - True membranes develop when conjunctival epithelium becomes necrotic and firm adhesions are formed between necrotic cells and the overlying coagulum. Membrane removal leaves raw, bleeding surface. Pseudomembranes are formed by inflammatory cells and exudates that are loosely adherent to the underlying epithelium and can be peeled away without bleeding and damage to ocular surface. Membranes and pseudomembranes are usually manifestations of beta hemolytic streptoccocal conjunctivitis, herpetic keratoconjunctivitis, chlamydial conjunctivitis in newborns, ligneous conjunctivitis, candida infections and can be found in diphtheria, Stevens-Johnson syndrome and after chemical burns.
Micro-pannus - It is subepithelial proliferation of fibrovascular tissue from limbus into the cornea that extends 1-2 mm beyond the normal vascular arcade. (Fig.10) It can be found in chlamydial, conjunctivitis, staphylococcal blepharoconjunctivitis, vernal conjunctivitis and after contact lens wear.
Fig. 10 Micro-pannus in staphylococcal blepharoconjunctivitis
Gross-pannus– Extends more than 2 mm beyond the normal vascular arcade. Superior pannus is typical manifestation of trachoma (Fig. 11) but can be occasionally seen in staphylococcal blepharitis, herpetic keratoconjunctivitis, atopic keratoconjunctivitis and in rosacea.
Fig. 11 Gross-pannus in trachomatous keratoconjunctivitis. (by courtesy of dr. Mohamed Higazy, Cairo, Egypt)
Conjunctival scarring – It can occur in a variety of inflammations (infectious, immunological, allergic, posttraumatic). Raw and denuded surfaces of conjunctiva can adhere and scar leading to symblepharon and shortening of the conjunctival fornices. The most pronounced scarring occurs in trachoma, chemical burns and in erythema multiforme, Stevens-Johnson and toxic epidermal necrolysis.