KERATOCONUS

DEFINITION

Keratoconus is a condition in which the cornea (the clear covering of the colored iris and black pupil) becomes protruded and irregular, affecting vision. It typically develops during teenage or young adulthood years, but can occur later. It tends to progress until the 30’s or 40’s and then tends to stabilize.

SYMPTOMS

Blurred vision, usually one eye worse the to the eye. It often causes changes in vision requiring frequent glasses prescription changes, which clear the vision initially but later don’t help the vision as much.

CAUSES

The cause is unknown, but eye rubbing is thought to be a factor in many patients. Occasionally keratoconus runs in families.

RISK FACTORS

EYE RUBBING

COMPLICATIONS

Cornea scarring can develop in severe cases. Acute corneal hydrops can develop in advanced cases. This is a condition where the membrane on the back layer of the cornea (Descemet’s membrane) tears and allows fluid to build up in the cornea causing pain and poor vision.

TESTS AND DIAGNOSIS

The diagnosis can usually be made during a slit lamp examination. Ancillary testing includes corneal curvature and thickness mapping (corneal topography and tomography) and measurement of the corneal thickness (pachymetry). Anterior segment optical coherence tomography (AS-OCT) may be helpful in some cases.

TREATMENT

Mild cases may just require routine observation and mapping with or without a new glasses prescription. Later it may worsen, requiring contact lenses to improve vision. Soft toric lenses, rigid gas permeable lenses, piggyback, hybrid (e.g. Synergeyes), or scleral (e.g. PROSE) lenses may be used. In some patients, contact lenses do not provide good, comfortable vision, and surgery may be an option. Intacs (plastic corneal inserts) may be an option for some patients with moderate keratoconus. Corneal transplantation (either partial thickness or full thickness) can be very successful for contact lens intolerant patients with keratoconus.

Progressive keratoconus, or alternatively eyes that develop progressive thinning and protrusion after refractive surgery such as LASIK, may be treatable with corneal crosslinking (CXL).

Acute corneal hydrops is initially managed with medications and usually resolves on its own over weeks to months, depending on its severity. Rarely, surgery may be required for hydrops.

PREVENTION

NO eye rubbing!! Routine eye examinations are recommended to monitor the condition. If progression of the condition is noted, corneal crosslinking should be considered. Corneal crosslinking is not indicated in eyes with significant corneal scarring or significant corneal thinning.