Microbial Keratitis

Question 1

What is Microbial Keratitis?

Answer 1

An infection of the cornea caused by bacteria, fungi, or viruses, leading to corneal opacification.

Question 2

What are the signs of Microbial Keratitis?

Answer 2

• Lid oedema
• Epiphora (excessive tearing)
• Mucopurulent or purulent discharge
• Conjunctival hyperaemia
• Corneal lesion or ring infiltrate
• Anterior chamber flare and hypopyon
• Inferior KP’s and iris nodules
• Posterior synechiae

Question 3

What are the common symptoms of Microbial Keratitis?

Answer 3

• Moderate to severe pain (unilateral)
• Redness
• Photophobia
• Discharge
• Blurred vision
• White or yellow spot on the cornea

Question 4

Why is microbial keratitis considered an emergency?

Answer 4

It is sight-threatening and requires urgent referral to an ophthalmologist with no delay in intervention.

Question 5

What should be done with contact lenses in cases of Microbial Keratitis?

Answer 5

Cease lens wear and retain lenses and the case for culture.

Question 6

What general treatments are used for Microbial Keratitis?

Answer 6

• Analgesia
• Cycloplegia
• Admission for frequent antibiotic drops if compliance is unlikely or if the infection is severe

Question 7

What is the purpose of a corneal scrape in Microbial Keratitis?

Answer 7

To obtain material for culture and polymerase chain reaction (PCR) to identify the causative organism.

Question 8

What antibiotics are used for bacterial keratitis?

Answer 8

Chloramphenicol and Gentamicin.

Question 9

What antiviral medication is used for viral keratitis?

Answer 9

Acyclovir, which can be used topically or systemically.

Question 10

What antifungal treatments are used for fungal keratitis?

Answer 10

• Amphotericin B 0.15%
• Econazole 1% (topical)
• Voriconazole (oral)

Question 11

How does microbial keratitis affect the cornea?

Answer 11

It causes corneal opacification and may result in a full-thickness corneal lesion with a ring infiltrate.

Question 12

What is hypopyon, and how does it relate to Microbial Keratitis?

Answer 12

Hypopyon is the accumulation of white blood cells in the anterior chamber, often seen in severe microbial keratitis.

Question 13

What are KP’s in Microbial Keratitis?

Answer 13

Keratic precipitates (KP’s), which are deposits on the corneal endothelium, usually found inferiorly.

Question 14

What is a posterior synechiae, and how does it relate to Microbial Keratitis?

Answer 14

It is an adhesion between the iris and the lens, which can occur in cases of severe inflammation, such as microbial keratitis.

Question 15

What is the prognosis of Microbial Keratitis?

Answer 15

The prognosis depends on the size, location, depth, and etiology of the corneal ulcer, as well as any pre-existing ocular conditions.

Question 16

Why is it important not to discard contact lenses or cases in Microbial Keratitis?

Answer 16

They may need to be retained for culture to help identify the causative organism.

Question 17

What is the role of polymerase chain reaction (PCR) in Microbial Keratitis?

Answer 17

PCR is used to identify the causative organism after a corneal scrape.

Question 18

What is a corneal ring infiltrate?

Answer 18

A circular area of infection in the cornea that can be full-thickness and is often seen in microbial keratitis.

Question 19

What factors influence the outcome of Microbial Keratitis?

Answer 19

• Size, location, and depth of the ulcer
• Etiology (bacterial, viral, fungal)
• Pre-existing ocular conditions

Question 20

What are the complications of untreated Microbial Keratitis?

Answer 20

Severe vision loss, corneal scarring, and potentially, permanent blindness.