PROTOZOAL KERATITIS

ACANTHAMOEBA KERATITIS
Acanthamoeba keratitis has recently gained importance because of its increasing incidence, difficulty in diagnosis and unsatisfactory treatment.
Etiology
Acanthamoeba is a free lying amoeba found in soil, fresh water, well water, sea water, sewage and air. It exists in trophozoite and encysted forms.

Mode of infection. Corneal infection with acanthamoeba results from direct corneal contact with any material or water contaminated with the organism.
Following situations of

HERPES ZOSTER OPHTHALMICUS Treatment

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Therapeutic approach to herpes zoster ophthalmicus should be vigorous and aimed at preventing severe devastating ocular complications and promoting rapid healing of the skin lesions without the formation of massive crusts which result in scarring of the nerves and postherpetic

HERPES ZOSTER OPHTHALMICUS

Herpes zoster ophthalmicus is an acute infection of Gasserian ganglion of the fifth cranial nerve by the varicella-zoster virus (VZV). It constitutes approximately 10 percent of all cases of herpes zoster.

Etiology
Varicella -zoster virus. It is a DNA virus and produces acidophilic intranuclear inclusion bodies. It is neurotropic in nature.

Mode of infection. The infection is contracted in childhood, which manifests as chickenpox and the child develops immunity. The virus then remains
dormant in the sensory ganglion of trigeminal nerve. It is thought that, usually in elderly people (can occur at any age) with depressed

HERPES SIMPLEX KERATITIS

Ocular infections with herpes simplex virus (HSV) are extremely common and constitute herpetic keratoconjunctivitis and iritis.
Etiology
Herpes simplex virus (HSV). It is a DNA virus. Its only natural host is man. Basically HSV is epitheliotropic but may become neurotropic.
According to different clinical and immunological
properties, HSV is of two types: HSV type I typically
causes infection above the

MYCOTIC CORNEAL ULCER

The incidence of suppurative corneal ulcers caused by fungi has increased in the recent years due to injudicious use of antibiotics and steroids.

Etiology
1. Causative fungi. The fungi which may cause corneal infections are :
i. Filamentous fungi e.g., Aspergillus, Fusarium, Alternaria, Cephalosporium, Curvularia and Penicillium.
ii. Yeasts e.g., Candida and Cryptococcus. (The fungi more commonly responsible for mycotic corneal ulcers are Aspergillus (most common), Candida and Fusarium).
2. Modes of infection
i. Injury by vegetative material such as crop leaf, branch of a

Marginal catarrhal ulcer

These superificial ulcers situated near the limbus are
frequently seen especially in old people.
Etiology
Marginal catarrhal ulcer is thought to be caused by a
hypersensitivity reaction to staphylococcal toxins. It
occurs in association with chronic staphylococcal
blepharoconjunctivitis. Moraxella and zzz  Haemophilus
are also known to cause such ulcers.
Clinical features
1. Patient usually presents with mild ocular irritation,
pain, photophobia and watering.

2. The ulcer is shallow, slightly infiltrated and often
multiple, usually associated with staphylococcal
conjunctivitis (Fig. 1).

Fig. 1. Marginal corneal ulcer in a patient with acute
conjunctivitis.

3. Soon vascularization occurs followed by
resolution. Recurrences are very common.
Treatment
1. A short course of topical corticosteroid drops
along with adequate antibiotic therapy often heals
the condition.
2. Adequate treatment of associated blepharitis and
chronic conjunctivitis is important to prevent
recurrences.