▃Anatomy of Conjunctiva
Conjunctiva is a thin, translucent mucous membrane. It lines the inner surface of eyelids and then reflects onto the surface of globe as far as the limbus (corneoscleral junction). Conjunctiva is divided into three parts, namely, palpebral conjunctiva, bulbar conjunctiva, and forniceal conjunctiva.
It extends from the mucocutaneous junction of the lid margins and lines the inside of the eyelids. It is subdivided into:
•Marginal conjunctiva: It extends from the anterior lid margin to approximately 2 mm on the back of the lid (up to sulcus subtarsalis or subtarsal sulcus). It is a transitional zone between the skin of the lid and the conjunctiva proper and made up of stratified epithelium.
•Tarsal conjunctiva: It is highly vascular and adherent to tarsal plates. In the upper eyelid, it is fully adherent to whole tarsal plate, while adherence is less marked in the lower eyelid.
•Orbital conjunctiva: It is loose and lies between the border of the tarsal plate and fornix.
It lines the anterior part of sclera and becomes continuous with corneal epithelium at the limbus. It is separated from anterior sclera by episcleral tissue and Tenon’s capsule. It is loosely attached to the underlying Tenon’s capsule and freely movable over sclera except around cornea (limbal conjunctiva) where the attachment is firm. Limbal conjunctiva, a part of bulbar conjunctiva, covers the limbal region and is continuous with the corneal epithelium.
It unites the palpebral and bulbar portions of conjunctiva. It is loose and thrown into folds. Plica semilunaris is a vertical semilunar fold present nasally and separates bulbar conjunctiva from caruncle at medial canthus, which is an ovoid mass covered by stratified squamous epithelium and contains hair follicles, sweat glands, and sebaceous glands (Fig. 5.1).
Conjunctiva consists of two layers, namely, epithelium and stroma. Epithelium is nonkeratinized and two to five layers thick. It is two-layered over palpebral conjunctiva and the layers gradually increase from fornix to limbus. It contains mucus glands, “goblet cells”, which secrete mucin for tear film. Stroma consists of richly vascularized connective tissue and consists of:
•Superficial adenoid layer: It contains lymphocytes, mast cells, and histiocytes. It does not develop until 2 to 3 months after birth. Hence, conjunctival inflammation in the newborn does not produce a follicular reaction.
•Deep fibrous layer: It consists of collagen and elastic fibers and merges with tarsal plates.
Conjunctiva consists of two types of glands, namely, mucin secreting glands and accessory lacrimal glands (Fig. 5.2).
These secrete mucin and include:
•Goblet cells–These are unicellular mucus glands located within epithelium of bulbar conjunctiva and fornix. These are most dense in inferonasal part of conjunctiva, so it is the best site for diagnostic biopsy.
•Crypts of Henle–These are present in tarsal conjunctiva.
•Glands of Manz– these are found in a circumferential ring of limbal conjunctiva.
Destructive disorders of conjunctiva damage the mucin secretors, leading to mucin deficiency which results in dry eye.
Accessory Lacrimal Glands
These are located in stroma and include:
•Glands of Krause–These are present in fornix.
•Glands of Wolfring–These are present along the upper border of superior tarsus and the lower border of inferior tarsus.
It is derived from trigeminal nerve. Long ciliary nerves supplying the cornea also supply the limbal conjunctiva. Branches from lacrimal nerve, infratrochlear (branch of nasociliary nerve), supratrochlear, and supraorbital (branches from frontal nerve) supply the rest of conjunctiva.
It is derived from peripheral tarsal arcade, marginal tarsal arcade, and anterior ciliary arteries (Fig. 5.3). Marginal arcade, which lies 2 mm away from the margin of the eyelids, supplies the marginal conjunctiva. Peripheral arcade lies near the peripheral border of tarsal plate. Its perforating branches pierce the Müllers muscle to reach the conjunctiva and gives off ascending and descending branches. Descending branches supply the tarsal conjunctiva and also anastomose with vessels from the marginal arcade. Ascending branches pass into the superior fornix and continue around the fornices to the bulbar conjunctiva as the posterior conjunctival arteries which supply the bulbar conjunctiva.
Anterior ciliary arteries run along the tendon of rectus muscle and gives off anterior conjunctival arteries. Anterior ciliary arteries send branches to the limbal conjunctiva. Anterior conjunctival arteries anastomose with terminal branches of the posterior conjunctival artery, forming a pericorneal plexus. Thus, the superficial and deep systems of vessels are closely connected in the limbal area.
•Lymphatics from lateral side drain into preauricular lymph nodes.
•Lymphatics from medial side drain into submandibular lymph nodes.
■Conjunctival Flora of Normal Eye
Eyelids and conjunctiva harbor a significant number of microorganisms. Organisms normally present in conjunctival sac are nonpathogenic. Frequent blinking mechanically washes away the bacteria by the tears. Bandaging arrests movements of lids and increases conjunctival sac temperature, leading to increase in bacterial content of conjunctiva. Also, low temperature of conjunctival sac, lysozyme (a bacteriostatic enzyme), and IgA in tears inhibit bacterial growth.
Organisms normally present in conjunctival sac include:
The organisms which are pathogenic and rarely found in normal eyes include:
The most dangerous pathogens in ocular infections include:
▃Clinical Features of Conjunctival Disorders (OP3.1,3.2)
Common symptoms of conjunctival disorders include:
•Foreign body sensation or grittiness.
•Bright light is resented (but if photophobia is present, it suggests associated corneal involvement or iritis).
Eye discharge involves a combination of exudates filtered from dilated blood vessels, mucus, tears, and variable amount of epithelial debris. The eyes produce mucus throughout the day but tears flush them out with each blink before it hardens in the eye. During sleep, blinking is absent and the eye discharge collects and crusts in the corners of the eyes. Therefore, some discharge in eyes upon waking is normal, but excessive discharge differing in consistency, color, and quantity could indicate an eye infection or a disease.
Types of Discharge
There are four types of discharges in the eye which are as follows:
•Watery discharge: It is composed of serous exudates and tear and is seen in viral conjunctivitis and acute allergic conjunctivitis.
•Mucoid discharge: It is seen in vernal conjunctivitis and dry eye.
•Purulent discharge: It is seen in acute bacterial infections.
•Mucopurulent discharge: Such discharge gives rise to gluing up of eyelids in the morning. It is seen in mild bacterial infections and chlamydial infections.
Conjunctival inflammatory reactions could be in the form of:
•Hyperemia of conjunctiva.
Hyperemia of Conjunctiva (Conjunctival injection)
It is the passive dilatation of conjunctival blood vessels and may be:
•More intense in fornices away from limbus– it indicates conjunctivitis (all types).
•Circum corneal or perilimbal congestion (ciliary congestion)– it indicates involvement of cornea, iris, or sclera.
Conjunctival congestion may be acute, transient, or chronic. Acute and recurrent occur due to concretions in palpebral conjunctiva or “in-growing” lashes. Transient congestion occurs due to foreign body. Chronic congestions occur due to dry, dusty climate, allergic conditions, and excessive ingestion of alcohol.
Topical instillation of decongestant drops (phenylephrine or naphazoline) blanch the blood vessels, providing temporary relief.
Chemosis (edema of conjunctiva)
It occurs due to exudation from abnormally permeable capillaries. It is particularly prominent in loosely attached bulbar and forniceal conjunctiva. The conjunctiva becomes swollen and gelatinous in appearance. Chemosis could be due to local or systemic causes.
Local causes include acute inflammation like:
•Severe infective conjunctivitis.
•Inflammation of accessory structures of eye such as stye, insect bite on lid, dacryocystitis, and periostitis.
Owing to obstruction of blood and/or lymph drainage, it may occur with:
•Carotico-cavernous fistula (Fig. 5.3).
•Decreased plasma osmotic pressure.
•Congestive heart failure.
•Superior vena cava syndrome.
It occurs due to rupture of small vessels. Fig. 5.4 describes the causes of subconjunctival hemorrhage..
Subconjunctival hemorrhage is symptomless and gets absorbed by itself within 2 to 3 weeks; however, the following points need to be kept in consideration:
•Cold compression in initial stages.
•Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) should be avoided.
•Artificial tears–if mild ocular irritation is present.
Follicles are lymph follicles with vascularization. These are prominent in the inferior forniceal conjunctiva. Table 5.1 describes the follicular reaction in case of eye conjunctival disorders.
Papillae are hyperplasia of the vascular system invaded by inflammatory cells. They form a mosaic-like pattern of elevated red dots.
A papillary reaction is more nonspecific being of less diagnostic importance than a follicular reaction (Table 5.2).
Membranes are made up of fibrinous exudate that may or may not be firmly adherent to the epithelium of conjunctiva. These may be pseudomembranes or true membranes.
These are formed when the coagulated exudates adhere to the inflamed conjunctival epithelium. Therefore, it can be easily peeled off, leaving the underlying epithelium intact. These occur in severe adenoviral conjunctivitis and gonococcal conjunctivitis.
•yellowish–white multiple, discrete round elevations.
•1–2 mm in diameter, encircled by tiny blood vessels
Follicles are most prominent in inferior forniceal conjunctiva but more numerous on upper palpebral conjunctiva in trachoma
Follicles are due to localized aggregation of lymphocytes in subepithelial adenoid layer of stroma. Follicles do not develop until about 2–3 months after birth.
Causes of follicular reaction include:
•Hypersensitivity to topical medications
Table 5.2 Papillary reaction
Glomerulus-like appearance of capillaries growing into epithelium.
Most frequent in upper palpebral conjunctiva. Papillae can only develop in palpebral conjunctiva and limbal bulbar conjunctiva where it is attached to deeper fibrous layer.
•Contact lens wear
•Superior limbic keratoconjunctivitis
These are formed due to permeation of inflammatory exudates into the superficial layers of conjunctival epithelium. Therefore, attempts to remove the membrane tear the epithelium and results in bleeding. These occur in bacterial conjunctivitis due to the Corynebacterium diphtheriae.
It is a dry and lusterless condition of the conjunctiva.
It is due to the deficiency of mucin which may occur as a sequel to a local disease of the conjunctiva, involving all its layers, or may be associated with general disease.
1.Xerosis due to local conjunctival diseases– it is a cicatricial degeneration of the conjunctiva due to:
•Diphtheritic membranous conjunctivitis.
•Prolonged exposure due to ectropion or proptosis.
The chief changes involve conjunctival epithelium and glands. The mucus secretion ceases and the epithelium becomes epidermoid like that of skin. This impaired secretory activity of conjunctiva results in xerosis in spite of normal or increased lacrimal secretion, as the watery tears then fail to moisten the conjunctiva.
2.Xerosis due to systemic diseases– it occurs due to vitamin A deficiency in the diet.
Subconjunctival scarring is significant tissue shrinkage with distortion of the fornices and/or the lids.
These can be due to:
•Trauma: surgical, thermal, radiational, mechanical, chemical, trichiasis, or entropion.
♢Ocular cicatricial pemphigoid (OCP).
♢Graft versus host disease.
The preauricular lymph nodes are typically affected.
The most common causes are:
•Bacterial conjunctivitis (particularly gonococcal).
•Parinaud oculoglandular syndrome.
▃Inflammation of Conjunctiva (Conjunctivitis (OP3.3))
Conjunctivitis is an inflammation of the conjunctiva. It may be of two types: infective and noninfective conjunctivitis.
Infective conjunctivitis may be:
Noninfective conjunctivitis may be:
•Giant papillary conjunctivitis.
Conjunctivitis may be acute or chronic. Conjunctivitis that persists for ≥ 4 weeks is considered chronic. Chronic conjunctivitis can be caused by a variety of microorganisms, environments, and environmental factors. Chronic conjunctivitis may occur due to:
•Inadequately treated acute conjunctivitis.
•Chronic bacterial conjunctivitis.
•Specific granulomatous conjunctivitis.
•Trachoma due to chlamydia trachomatis.
Bacterial conjunctivitis is caused by staphylococcus, streptococcus pneumoniae, hemophilus, corynebacterium diphtheriae, neisseria, moraxella, and Gram –ve bacilli. It is characterized by conjunctival hyperemia, lid edema, and mucopurulent discharge in one eye. The second eye becomes involved 1 to 2 days later. Flowchart 5.1 describes the pathophysiology of bacterial conjunctivitis.
Depending on the onset, it may be acute, hyperacute, or chronic (Table 5.3).
Table 5.3 Types of bacterial conjunctivitis
•Acute catarrhal or mucopurulent conjunctivitis
•Acute purulent conjunctivitis
•Acute membranous conjunctivitis
•Acute pseudo-membranous conjunctivitis
•Chronic bacterial conjunctivitis
•Chronic angular conjunctivitis
Acute Mucopurulent and Purulent Conjunctivitis (Fig. 5.5)
The most common causative bacteria are:
•Staphylococcus aureus (a Gram + ve cocci)– its pathogenicity is proportionate to its coagulase activity.
•Koch–Weeks bacillus (Haemophilus aegyptius)– it is a Gram −ve bacilli.
The clinical presentation depends on the virulence and pathogenicity of the organism and the host immune response. Symptoms include:
•Redness of the eye.
•Sticking together of lid margins, particularly in the morning, due to accumulation of discharge at night.
•Foreign body sensation,
•Colored halos due to prismatic action of discharge across the cornea.
Clinical signs include:
•Conjunctival congestion which is less marked in circum corneal zone.
•Flakes of mucopurulent discharge at fornices, canthi, and lid margins.
•Cilia are usually matted together.
If untreated, the disease may be complicated by:
•Marginal corneal ulcer.
•Blepharitis or dacryocystitis.
•Eyes should not be bandaged because bandaging the eye will raise the temperature of conjunctival fornix, which will flare up the infection.
•Dark glasses must be used to avoid photophobia.
•Irrigation of conjunctival sac is carried out to remove the discharge, although frequent irrigation will wash out the lysozyme in the tears.
•Topical broad-spectrum antibiotics such as chloramphenicol, ciprofloxacin, gatifloxacin, and moxifloxacin are instilled 4 to 6 times a day.
•Antibiotic eye ointment is used at night.
•No steroids should be applied as the infection may flare up.
Acute Pseudomembranous and Membranous Conjunctivitis
It is the inflammation of conjunctiva characterized by the formation of pseudo membrane or fibrinous membrane covering the conjunctival surface in certain infections (Fig. 5.6).
Membrane formation may take place in infections due to:
•Beta hemolytic streptococci.
Diphtheritic infection due to corynebacterium diphtheriae occurs chiefly in children, resulting in membrane formation. Membranous conjunctivitis of diphtheritic origin is often severe. Streptococcal conjunctivitis occurs in association with measles, whooping cough, and influenza. Chemical and thermal burns may also cause membrane formation.
Mild cases are characterized by swelling of the lids, mucopurulent or sanguinous discharge, and white pseudo membrane on palpebral conjunctiva.
Severe cases are characterized by brawny lids and marked chemosis of conjunctiva. There is infiltration of conjunctiva with semisolid exudates impairing mobility and compressing the vessels. A true membrane is present which covers the whole palpebral conjunctiva. It is seldom found on the bulbar conjunctiva. The membrane separates less easily and separation may lead to bleeding. This form is referred to as membranous conjunctivitis. Regional (preauricular) lymph nodes are usually enlarged.
After the stage of infiltration, cornea and underlying conjunctiva tend to necrotize. The necrosed part sloughs out and may lead to corneal ulceration. Adhesions form between the palpebral and bulbar parts of conjunctiva (symblepharon).
In children who are not immunized, every cause is treated as diphtheritic infection. It consists of:
•Freshly made topical (10,000 units/mL) penicillin drops from injectable solution are instilled on an hourly basis.
•Systemic administration of penicillin (crystalline penicillin 5 lacs units) on a 12-hour basis.
•Antidiphtheritic serum (4000–10,000 units repeated on a 12-hour basis).
•If cornea is involved, then cycloplegics (atropine 1%) are administered.
•In nondiphtheritic conjunctivitis, systemic and topical antibiotics are prescribed.
If the membrane is removed inadvertently, it may precipitate symblepharon. So, removal of membrane is not required.
Gonorrhoeal (Hyperacute) Conjunctivitis
The severe form of acute purulent conjunctivitis is due to Neisseria gonorrhoeae (Gram –ve
diplococci). This form of conjunctivitis is also termed hyperacute conjunctivitis. The disease is venereal in origin and the infection is transmitted from the genitals to the eye. Gonorrhoeal conjunctivitis occurs in two forms:
•In newborns, it occurs as ophthalmia neonatorum.
•In adults, it occurs as severe purulent conjunctivitis.
•Pain and redness in the eye.
•Blurring of vision.
•Gritty sensation in the eye.
•Eye ball–painful and tender.
•Lids–tense and swollen.
•Conjunctiva–chemosed and bright-red velvety.
•Discharge–purulent, copious, and thick discharge.
•Lymph nodes–preauricular lymph nodes are enlarged.
In gonococcal conjunctivitis, urethritis is almost present. Coincidence of urethritis with severe purulent conjunctivitis is the important point in diagnosis.
As Neisseria gonorrhoeae (gonococcus) can invade intact corneal epithelium, so corneal complications are the rule. The whole cornea becomes hazy with a gray area of necrosis in the center. Marginal ulcers usually develop due to retention of pus in the angle formed by chemotic conjunctiva. The ulcer produced progresses resulting in perforation. Iridocyclitis may develop independently of perforation.
Systemic complications include:
Systemic therapy: Gonococcal infection is usually treated with a third-generation cephalosporin such as ceftriaxone; quinolones are alternatives.
•Gonococcal conjunctivitis without septicemia in adults is treated with a single dose of ceftriaxone 1 g IM.
•Conjunctivitis with corneal involvement is treated with ceftriaxone 1 g IM or IV on a 12-hour basis for 5 days.
•Oral norfloxacin or ciprofloxacin are also effective.
•Irrigation of the eyes with warm saline.
•Intensive therapy with antibiotic eye drops such as quinolones (e.g., ofloxacin and ciprofloxacin eye drops) and aminoglycosides (tobramycin or gentamicin eye drops).
•Antibiotic ointment (e.g., erythromycin or bacitracin) is applied at night. Ointments and gels provide a higher concentration for longer periods than drops but they are not used during day time because of blurred vision.
•Cycloplegics (atropine 1 percent) must be applied if the cornea and uvea are
•Patient and the sexual partner should be referred for evaluation of other sexually transmitted diseases.
•If venereal disease is present in teenagers, also treat with single dose of azithromycin (1 gm) because over 30% of these patients will be afflicted with concurrent chlamydial diseases.
Chronic Bacterial Conjunctivitis
Conjunctivitis longer than three weeks duration is defined as chronic bacterial conjunctivitis. It may result from several organisms.
It is most commonly caused by Staphylococcus species, although other bacteria are occasionally involved. This type of conjunctivitis may often be associated with chronic dacryocystitis, rhinitis, and blepharitis.
Staphylococcus aureus colonizes the eyelid margin from which it can cause direct infection of conjunctiva or may elaborate exotoxins to cause conjunctival inflammation. Recurrent styes and chalazia of the lid margin are concurrently seen from chronic inflammation of the meibomian glands. Meibomian glands secrete an oily component of the tear film. When inflamed, these glands produce chronic inflammation of eyelid margins and conjunctiva (Fig. 5.7). Symptoms include the following:
•Discharge is slight but there is abnormal amount of secretion from the meibomian glands.
It is marked by congestion of posterior conjunctival vessels when the lower lid is pulled down. The upper and lower palpebral conjunctiva may be congested with papillary hypertrophy.
It consists of:
•Elimination of cause.
•Topical antibiotics to eliminate the infection.
•Astringent eye drops for symptomatic relief.
Chronic Angular Conjunctivitis
Angular conjunctivitis is a type of chronic conjunctivitis characterized by mild grade inflammation confined to the conjunctiva and lid margins near the angles (hence the name) associated with maceration of the surrounding skin.
It is typically caused by Moraxella–Axenfeld, a Gram −ve diplobacilli. The bacilli are placed end to end, so the disease is also called diplobacillary conjunctivitis. The organism produces a proteolytic enzyme which macerates the epithelium of the lid margin.
The diplobacilli is often present in the nasal discharge in cases of angular conjunctivitis.
Mode of Infection
Infection is transmitted from nasal cavity to the eyes by contaminated fingers or handkerchief.
The proteolytic enzyme produced by Moraxella–Axenfeld collects at the angles by the action of tears and thus macerates the epithelium of conjunctiva, lid margin, and the skin of the surrounding angles of eye. The maceration is followed by mild grade chronic inflammation. The skin may show eczematous changes.
Symptoms include irritation in the eye, itching, and burning sensation in the eye, collection of dirty-white foamy discharge at the angles, and redness in the angles of eye.
•Hyperemia of bulbar conjunctiva near the canthi.
•Hyperemia of lid margin near the angles.
•Excoriation of the skin around the angles.
•Presence of foamy mucopurulent discharge at the angles.
•If the condition is untreated, it becomes chronic and may give rise to blepharitis.
•A shallow, marginal, and catarrhal corneal ulceration may occur.
•Tetracycline or oxytetracycline ointment (1%) two to three times a day for 2 weeks will eradicate the infection.
•Topical eye drops containing zinc inhibit the proteolytic ferment and thus help in reducing the maceration.
Viral conjunctivitis is extremely common and highly contagious. Most of the cases resolve spontaneously within days to weeks. The diagnosis is made clinically, hence laboratory investigations and viral cultures are rarely conducted. Viral conjunctivitis (Fig. 5.8) is caused by adenoviruses, herpes simplex, and less frequently by varicella-zoster virus, picornaviruses, pox, and papilloma viruses.
The infection is transmitted by:
•Contact with upper respiratory tract droplets.
•Infected swimming pools.
•Infected ocular instruments like tonometers.
Acute viral conjunctivitis may present in three clinical forms: Acute serous conjunctivitis, acute hemorrhagic conjunctivitis, and acute follicular conjunctivitis. The follicular conjunctival reaction is more common in viral infections due to adenoviruses and herpes viruses. It can be acute or chronic. Acute follicular conjunctivitis may also occur in chlamydial inclusion conjunctivitis.
Patient complains of the following symptoms:
•Feeling of discomfort and foreign body sensation.
•Watering of the eyes.
•Mild mucoid discharge.
•A history of fever, pharyngitis, cough or rhinorrhea may be part of the viral prodrome.
Typical signs of viral conjunctivitis are as follows:
•Copious, clear, serous, and watery discharge.
•Follicular conjunctival reaction.
•Tender preauricular lymph node.
These infections are highly contagious and occur in epidemics. The onset of infection is abrupt. Patients with adenoviral conjunctivitis are contagious to others for 3 weeks. Subtypes of adenoviral conjunctivitis include:
•Epidemic keratoconjunctivitis (EKC).
•Pharyngoconjunctival fever (PCF).
Epidemic Keratoconjunctivitis (EKC)
EKC is caused by adenovirus of serotypes 3, 7, 8, and 19 (Fig. 5.9).
EKC is characterized by a sudden onset of signs and symptoms (Fig. 5.10).
•Foreign body sensation.
•Excessive watery discharge.
•Follicular conjunctival reaction.
•Discrete subepithelial corneal infiltrates which appear approximately 2 weeks after the onset of conjunctivitis.
These are associated with photophobia. These gradually diminish and finally disappear, but may persist for weeks to months or even years.
Occasionally, pseudo membranes develop on palpebral conjunctiva.
EKC is a highly contagious disease and its transmission usually occurs from eye to finger to eye. Tonometers and eye drops are the other routes of transmission. It is nonspecific and symptomatic with: