All of the following are true about the condition of the cornea shown in the the picture below except ?
A. Can be seen in Down’s syndrome.
B. It manifests just after birth.
C. Munson sign is characteristic.
D. Corneal transplantation is needed in severe cases.
Ans:B. It manifests just after birth.
The patient is presenting with Keratoconus.
- It is a disorder of the eye which results in progressive thinning of the cornea.
- Keratoconus has been associated with atopic diseases,Alport syndrome, Down syndrome and Marfan syndrome.
- It occurs most commonly in late childhood to early adulthood.
- This may result in blurry vision, double vision, nearsightedness, astigmatism, and light sensitivity.
- The classic symptom of keratoconus is the perception of multiple “ghost” images, known as monocular polyopia. Usually both eyes are affected.
- Munson’s sign ( the lower lid bulges when the patient looks down).
- In more severe cases a scarring or a circle may be seen within the cornea.
- Diagnosis is by examination with a slit lamp.
- Retinoscopy: a scissor reflex action of two bands moving toward and away from each other like the blades of a pair of scissors.
- A handheld keratoscope(“Placido’s disk”)can provide a simple noninvasive visualization of the surface of the cornea by projecting a series of concentric rings of light onto the cornea.
- A more definitive diagnosis can be obtained using corneal topography.
- Measurement of Corneal thickness by Pachymeter.
- Once keratoconus has been diagnosed, its degree may be classified by several metrics:
- The steepness of greatest curvature from ‘mild’ (< 45 D), ‘advanced’ (up to 52 D) or ‘severe’ (> 52 D);
- The morphology of the cone: ‘nipple’ (small: 5 mm and near-central), ‘oval’ (larger, below-center and often sagging), or ‘globus’ (more than 75% of cornea affected);
- The corneal thickness from mild (> 506 μm) to advanced (< 446 μm).
- Initially the condition can typically be corrected with glasses or soft contact lenses.
- As the disease worsens rigid contact lenses, known as rigid,gas permeable lenses may be required.
- In most people the disease stabilizes after a few years without severe vision problems.
- In a small number of people scarring of the cornea occurs and a corneal transplantation is required.