Page 44 - NAME OF CONDITION: REFRACTIVE ERRORS

NAME OF CONDITION: MICROBIAL KERATITIS

I. WHEN TO SUSPECT/ RECOGNIZE?

a) Introduction:

Microbial keratitis is an important cause of avoidable monocular blindness in India.
Young adults in their prime working age group are most commonly affected and hence
the loss of man years of productivity is extremely high. The therapeutic results are less
than satisfactory even in the most optimistic situations. Even the so called successfully
treated cases end up with a corneal scar which might impair vision. The cost of
treatment is compounded by the long treatment schedules and frequent follow ups to
the hospital A significant percentage of patients fail medical treatment, and will require
corneal transplantation. The availability of donor corneas in India is extremely low.

Currently only 5% of the requirement is being met. Under these circumstances, it
becomes very clear that adequate and appropriate therapy at all levels and more
importantly preventive strategies at the primary level will go a long way in preventing
this unnecessary catastrophe.

b) Case definition:

A theoretical definition of a corneal ulcer is a loss of the overlying epithelium with
underlying infiltration. However, for all practical purposes, microbial keratitis includes
any condition which causes suppurative infection of the cornea. Further progress of the
disease can cause necrosis of the deeper stromal tissue, resulting in perforation and loss

of intraocular contents.
II. INCIDENCE OF THE CONDITION IN OUR COUNTRY

It is an extremely common condition causing significant ocular morbidity in our country.
In fact, an editorial in the British Journal of Ophthalmology called it as an silent epidemic
Gonzales et al found that the annual incidence of corneal ulceration in Madurai district
in South India was 113 per 1,00,000 people. By applying the 1993 corneal ulcer
incidence rate in Madurai district to whole of India, about 8,40,000 people are likely to
develop a corneal ulcer in a year Even this figure is quoted as an under estimation when
compared to other SAARC countries. This figure is thirty times more than the number of
corneal ulcers seen in the United States.
III. DIFFERENTIAL DIAGNOSIS

The term microbial keratitis is often reserved for conditions caused by microorganisms
which results in suppuration. The common causative organisms can be bacteria, fungi or,
parasites. Other conditions which can mimic a suppurative keratitis includes
a. Viral keratitis

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