B. CHRONIC INFECTIVE CONJUNCTIVITIS
It is a chronic specific communicable disease caused by Chlamydia trachomatis infection of the epithelium of the conjunctiva causing papillae and follicles and cornea causing pannus and it heals by cicatrization.
It is caused by Chlamydia trachomatis serotypes A, B & D. Chlamydia is similar to viruses in that it can diffuse through membranes and forms inclusion bodies formed of carbohydrates and proteins. Also chlamydia can be cultured only on living cells, not on bacterial media. But it differs from viruses in that:
1. Much bigger in size.
2. It has a DNA material, cytoplasm and metabolism. So that they can be killed by sulfonamides and broad spectrum antibiotics.
3. Chlamydia reproduces by binary fission as bacteria, not by replication as viruses.
4. It lives in the cytoplasm of the infected cell, so that it causes intracytoplasmic basophilic (stained blue with Gimsa stain) inclusion bodies.
Life cycle of chlamydia: The infective form is called “the elementary body”. After infecting the epithelial cell it enlarges in size forming “the initial bodies”. The initial bodies divide and accumulate forming “the intracytoplasmic inclusion bodies”. Finally the infected cell ruptures leading to release of a large number of elementary bodies that infect other cells.
N.B. They are poorly antigenic, so that they can cause repeated infection.
- It is endemic in Egypt and middle east.
- More common in patients with poor hygiene.
- The mode of infection: Infection occurs by transmission of infective discharge by fingers, utensils and flies.
- I.P.: 1 - 2 weeks.
- The first infection occurs in the age of 6 months - 2 years.
Chlamydia exclusively infects the epithelial cell, then its toxins diffuse to the underlying layers causing hyperemia, follicles and papillae. This pathology occurs in the upper half of both the cornea and conjunctiva. The lower half is uncommonly involved.
Type of patient:
- The commonest age is 6 months to 2 years.
- It affects both sexes equally, but females are more liable for complications.
- Gritty or sandy sensation.
- Scanty muco-purulent discharge.
- Heaviness of the lids.
- Photophobia due to corneal affection.
I. Conjunctival manifestations (Mac Callen's classification):
Stage T-I: Stage of non expressible (immature) follicles:
- There is diffuse hyperemia and immature follicles that are pale and not elevated above the surface of conjunctiva.
- Follicles are subepithelial aggregation of lymphocytes, plasma cells, specific giant cells called "Leber's cells" and fibroblasts. Follicles are pale because they are not invaded by blood vessels.
T-II,a: Stage of expressible (mature) follicles:
Trachomatous follicles are the only follicles that undergo gelatinous degeneration in their central parts. So that they become elevated and expressible.
T-II,b: Stage of papillae:-
Papillae are reddish elevations above the surface of conjunctiva. This stage is further subdivided according to the type of papillae into:
T-II,b1: Typical trachomatous papillae.
They are folds of hyperplastic epithelium with vascular connective tissue core rich in inflammatory cells. They give the surface a velvety appearance. The main features of trachomatous papillae are:
- Rounded top and finger like.
- Present in the upper tarsal conjunctiva and upper fornix.
T-II,b2: Trachomatous papillae in the presence of spring catarrhal: The papillae are flat topped.
T-II,c: Trachoma with chronic gonococcal conjunctivitis:
Gonococci are present in the discharge.
T-II,v: Stelwag's brawny edema of the lid:
There is degeneration of the tarsus with intense plasma cell infiltration (rare).
Stage T-III: Healing (cicatrizing) trachoma:
Fibrosis starts to appear in the tarsal conjunctiva resulting in:
- Linear scars.
- Arlet's line which is fibrosis in sulcus subtarsalis.
- Post trachomatous degenerations (PTDs): They are accumulated debris and necrotic cells in the clefts between the papillae. They may be calcified and called post trachomatous concretions (PTCs).
Stage T-IV: Healed trachoma:
The tarsal conjunctiva is fibrosed, greyish and atrophic with Arlet's line, PTDs and PTCs. It obscures the Meibomian glands.
- Stages I & II are active and infectious (the organism is present in the conjunctival scrap).
- Stages III & IV are inactive and non infective (the organism is not present in the discharge).
II. Corneal manifestations of trachoma:
1. Stage of avascular superficial keratitis.
2. Trachomatous pannus:-
Pannus by definition means superficial vascularization and infiltration with chronic inflammatory cells in the cornea.
* Trachomatous pannus has the following characteristics:
1. Limited to the upper 1/2 of the cornea.
2. Vessels and infiltration are subepithelial. Bowman's membrane is damaged later on causing permanent superficial scar (healed pannus).
3. Vessel are straight and parallel.
* Fate of pannus: - If Bowmann's membrane is not injured resolution occurs.
- If Bowmann's membrane is injured pannus siccus will occur.
* Stages of trachomatous pannus:
1. Progressive pannus: Cellular infiltration precedes blood vessels.
2. Regressive pannus: With the cure of the condition cellular infiltration regresses, but vessels remain. So that infiltration will recede behind the level of vascularization.
3. Healed pannus (pannus siccus): It occurs after complete healing of the disease, and remains forever. There is superficial arc like opacity due to injury of Bowman's membrane. Vessels are collapsed, but not obliterated (ghost vessels). They fill with blood when the cornea is irritated by anything as F.B..
* Types of pannus according to the clinical appearance:
1. Pannus tenius: Thin pannus.
2. Pannus vasculosus: Highly vascular pannus.
3. Pannus carnosus (fleshy pannus): High cellular infiltration.
4. Pannus annulosus.
5. Pannus siccus: Healed pannus.
3. Corneal follicles:
- They are ordinary trachomatous follicles. When they are active they are tiny, elevated and surrounded by vessels looking like a rosette (Herbert's rosettes).
- After they heal, they leave small depressions called Herbert's pits.
4. Trachomatous corneal ulcers:
Two types of corneal ulcers can occur in a case of trachoma:
1. Typical trachomatous ulcers: They are microscopic horizontal superficial ulcers caused by Chlamydia trachomatis itself. They may occur in the following sites:
- At the end of pannus (the commonest).
- Beyond pannus.
- Within the pannus.
2. Central corneal ulcers: They are bacterial ulcers that are predisposed by trauma by PTDs or rubbing lashes.
N.B. Diagnostic signs of trachoma:
I. In the active stages (I & II):
- The expressible follicles and the typical papillae.
- The typical pannus.
- Herbert's rosettes.
- Basophilic intracytoplasmic I.B. and Leber's cells in conjunctival scraping.
II. In the inactive stages (III & IV):
- Arlet's line.
- PTDs & PTCs.
- Herbert's pits.
The recent WHO classification of trachoma:-
TF: More than 5 follicles larger than 0.5 mm.
TI: Intense conjunctival inflammation.
TS: Scarring of palpebral conjunctiva.
CO: Corneal opacities affecting the pupillary area causing drop of vision.
1. From other causes of follicular conjunctivitis.
2. Trachomatous papillae from palpebral spring catarrhal.
3. Trachomatous pannus from other causes of pannus.
Complications of trachoma:-
1. Lid complications (more in the upper lid):
- Trichiasis (usually multiple).
- Cicatricial entropion.
- Mild ptosis due to paralysis of Muller's muscle.
- Chronic Meibomianitis.
2. conjunctival complications:
- Posterior symblepharon (shallow fornix). It may obliterate ducts of the main lacrimal gland leading to loss of reflex lacrimation.
- Xerosis due to atrophy of goblet cells.
3. Corneal complications:
- Corneal ulcers.
- Corneal opacities.
- Complications of xerosis.
- Keratectasia (very rare).
4. Lacrimal complications:
- Fibrosis of lacrimal puncti or canaliculi.
- Fibrosis of NLD leading to chronic dacryocystitis.
Treatment of trachoma:-
A. Prophylactic treatment:
1. Combat flies and raise the hygienic habits.
2. Avoid cross infection by washing the fomites and instruments used in examination of a patient.
B. Curative treatment (sulfa and antibiotics):
1. Sulfa drugs:
- Sulfacetamide eye drops 10 - 30 % every 2 hours for 1 month.
- Sulfadiazine tablets 1 gm tds. for 2 weeks.
* Sulfa drugs act by interference with folic acid metabolism.
* Their side effects are:
- Urinary crystals.
- Hypersensitivity reactions as drug rash, aplastic anemia and agranulocytosis.
- Contraindicated in favism (G6PD deficiency).
- Eye ointment 5 times a day (if used without sulfa) or at bed time (when sulfa drops are used during day time).
- Systemic dose 250 mg 4 times every day for 2 weeks.
* They interfere with the protein metabolism of the organism.
3. Other broad spectrum antibiotics can be used as chloramphenicol 0.4% eye drops.
C. Treatment of complications:
a. For corneal ulcers we use atropine and local broad spectrum antibiotics. Bandage is done when there is no discharge.
b. Surgical removal of PTDs and PTCs because they rub the cornea and cause gritty sensation.
c. Treatment of upper lid fibrotic complications:
- Trichiasis: - Electrolysis if < 4 lashes.
- Z plasty if near to lateral canthus.
- Van Millengen’s operation if central.
- Cicatricial entropion ----> Snellen's operation.
d. Treatment of xerosis by artificial tears.
N.B. Other lines of treatment:
- Painting with chemicals as copper sulphate and silver nitrate.
- Shaving of papillae.
- Expression of follicles by Grade's forceps.
- Shaving of pannus carnosus.
- Perilimbal cautery of pannus vasculosus.
2. ANGULAR CONJUNCTIVITIS
See angular blepharo-conjunctivitis.
3. FUNGAL (CANDIDIAL) CONJUNCTIVITIS
Fungal conjunctivitis is predisposed by the chronic abuse of local steroids and antibiotics. It is characterized by discharge of whitish plaques and sometimes membrane formation. Scraping of the conjunctiva shows the budding yeast plus PNL reaction.