Describe the types of corneal opacity and their management.

Types of Corneal Opacity

• Assessment — the site (central or peripheral), size, density and depth; whether the visual axis is involved; the associated astigmatism; and, essentially, the state of the eye behind it — because grafting a cornea in front of a blind eye achieves nothing
• Assessing the posterior segment behind an opaque cornea — perception OF light with accurate projection OF rays in four quadrants.

Management

• Prevention is the whole of the subject in India, since corneal opacity is a leading cause of avoidable blindness: prompt and correct treatment of corneal ulcers; avoidance of over-the-counter steroids; treatment of trachoma, vitamin A deficiency and ophthalmia neonatorum; eye protection at work; and management of trichiasis and lid disease
• Optical measures — a rigid gas-permeable contact lens for the irregular astigmatism of a superficial scar, which is often more effective than any surgery; and a pinhole or a stenopaeic slit
• Superficial opacities — phototherapeutic keratectomy (PTK) with the excimer laser, for anterior opacities within 100 micrometres of the surface; and superficial keratectomy

Applied Aspects

• Test projection of rays before promising anything; inaccurate projection behind an opaque cornea means posterior segment disease and a graft will not restore vision
• Get a B-scan in every dense corneal opacity being considered for surgery; a retinal detachment behind a leucoma changes the plan entirely
• Try a rigid contact lens first in irregular astigmatism from a superficial scar; it is reversible, cheap and frequently sufficient
• Consider that a faint central opacity may disable more than a dense eccentric one; the patient complaining of glare with a "minor" scar is not exaggerating