**2. Clinical features**

#### **2.1. Symptoms**

In the absence of secondary infection, symptoms are minimal and include mild foreign body sensation in the eyes, occasional lacrimation, slight stickiness of the lids and scanty mucoid discharge. In the presence of secondary infection symptoms of acute mucopurulent conjunc‐ tivitis develop.

#### **2.2. Signs**

#### *2.2.1. Conjunctival*


and caruncle. Sometimes, follicles may be seen on the bulbar conjunctiva. Follicles are formed due to the scattered aggregation of lymphocytes and other cells in the adenoid layer. Central part of each follicle is made up of mononuclear histiocytes, few lympho‐ cytes and large multinucleated cells called Leber cells. The cortical part is made up of zone of lymphocytes showing active proliferation. Blood vessels are present in the most peripheral part. In later stages signs of necrosis are also seen.


#### *2.2.2. Corneal*


Pannus may be progressive (infiltration of cornea is ahead of vascularization) or regressive also termed pannus siecus (vessels extend a short distance beyond the area of infiltration).


#### **2.3. Differential diagnosis**

**1.** Presence of large multinucleated Leber cells and signs of necosis differentiate trachoma follicles from Adenovirus follicles conjunctivitis.

The distribution of follicles in trachoma is mainly on upper palpebral conjunctiva and for‐ nix. Sometimes, follicles may be seen on the bulbar conjunctiva.

The corneal involvement of the disease includes lymphoid follicle formation at the limbus. This is a characteristic feature of trachoma and can lead to the development of Herbert's pit.

Associated signs such as papillae and pannus are characteristic of trachoma.

**2.** Trachoma with predominant papillae is differentiated from palpebral form of spring ca‐ tarrh as follows:

Papillae are large in size and usually there is typical cobble-stone arrangement in spring ca‐ tarrh.

The pH of tears is usually alkaline in spring catarrh, while in trachoma it is acidic.

Discharge is ropy in spring catarrh

and caruncle. Sometimes, follicles may be seen on the bulbar conjunctiva. Follicles are formed due to the scattered aggregation of lymphocytes and other cells in the adenoid layer. Central part of each follicle is made up of mononuclear histiocytes, few lympho‐ cytes and large multinucleated cells called Leber cells. The cortical part is made up of zone of lymphocytes showing active proliferation. Blood vessels are present in the most

**3.** Papillary hyperplasia: Papillae are reddish, flat topped raised areas which give red and velvety appearance to the tarsal conjunctiva. Each papilla consists of central core of nu‐ merous dilated blood vessels surrounded by lymphocytes and covered by hypertrophic

**4.** Conjunctival scarring may be irregular, star-shaped or linear. Linear scar present in the

**5.** Concretions may be formed due to accumulation of dead epithedial cells and inspissat‐

**2.** Herbert follicles refer to typical follicles present in the limbal area. These are histologi‐

**3.** Pannus which is an infilteration of the cornea associated with vascularization, can de‐ velop at any point along the limbal margin but is most pronounced at the superior lim‐ bal margin. The vessels are superficial and lie between epithelium and Bowman's

Pannus may be progressive (infiltration of cornea is ahead of vascularization) or regressive also termed pannus siecus (vessels extend a short distance beyond the area of infiltration).

**4.** Corneal ulcer may sometimes develop at the advantage of pannus. Such ulcers are usu‐

**5.** Herbert pits are the oval or circular pitted scars, left after healing of Herbert follicles in

**6.** Corneal opacity may be present in the upper part. It may even extend down and in‐

**1.** Presence of large multinucleated Leber cells and signs of necosis differentiate trachoma

The distribution of follicles in trachoma is mainly on upper palpebral conjunctiva and for‐

volve the papillary area. It is the end result of trachomatous corneal lesions.

peripheral part. In later stages signs of necrosis are also seen.

epithelium.

232 Common Eye Infections

*2.2.2. Corneal*

the limbal area.

**2.3. Differential diagnosis**

sulcus subtarsalis is called Arlt's line.

cally similar to conjunctival follicles.

ed mucus in the depressions called glands of Henle.

**1.** Superficial Keratitis may be present in the upper part.

membrane; and later on the Bowman's membrane is destroyed.

ally shallow which may become chronic and indolent.

follicles from Adenovirus follicles conjunctivitis.

nix. Sometimes, follicles may be seen on the bulbar conjunctiva.

The corneal involvement of the disease includes lymphoid follicle formation at the limbus. This is a characteristic feature of trachoma and can lead to the development of Herbert's pit. In trachoma, there may be associated follicles and pannus.
