Page 47 - NAME OF CONDITION: REFRACTIVE ERRORS

Cornea:

Epithelium, including defects and punctate keratopathy, edema

Stroma, including ulceration, thinning, perforation, and infiltrate (location [central,
peripheral, perineural, surgical, or traumatic wound], density, size, shape [ring], number
[satellite], depth, character of infiltrate margin [suppuration, necrosis, feathery, soft,
crystalline], color), edema

Signs of corneal dystrophies (e.g., epithelial basement membrane dystrophy)

Previous corneal inflammation (thinning, scarring, or neovascularization)

Signs of previous corneal or refractive surgery

Fluorescein (or, occasionally, rose bengal staining) of the cornea is usually performed and
may provide additional information about other factors, such as the presence of dendrites,
pseudodendrites, loose or exposed sutures, foreign body, and any epithelial defect.

Clinical features suggestive of bacterial keratitis include dense suppurative stromal
infiltrate with distinct edges and edema. The symptoms are typically more prominent than
the signs. Fungal keratitis presents with dry raised surface and feathery indistinct margins.
Accompanying satellite lesions may be present in few cases. Acanthamoeba keratitis
usually presents with a ring shaped stromal infiltrate, as a late clinical feature and
commonly it is misdiagnosed as viral keratitis. It has to be emphasized however that all
these features are only suggestive of the organism and microbiological confirmation should
be sought for proper identification.

b) Investigations:

Microbiological investigations:

While characteristic clinical features have been described for ulcers caused by different
microorganisms, it is difficult to confirm these, especially after the disease has become well
established. Patients present late in our country and by this time, the clinical demarcation
between the ulcers caused by bacteria and fungi are usually lost. Since bacteria and fungi
cause an almost equal proportion of keratitis in our country, it is highly essential to perform
at least a smear test before initiating the treatment. Corneal infective material is obtained
by scraping after instilling a topical anesthetic agent (4% lignocaine) and using a flame
sterilized platinum spatula, blade or other similar sterile instrument. The material is
obtained from the advancing borders; ulcer base and edges. Two smears are initially
prepared – one with Gram’s stain (for identifying bacteria, fungi, and Acanthamoeba) and

the other with 10% potassium hydroxide (for fungus).

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