Question

1. Ms Duffy is 28 years old and wears spectacles. Over the last three years her vision has been worsening even with spectacles. She was examined by an eye doctor and diagnosed to have thinner and steeper than normal corneas with vision impairment in both eyes but more in the left than right eye. Her corneal condition and vision were expected to continue to worsen without intervention. Thus, the eye doctor performed a negligibly invasive treatment procedure on her eyes, first in the left eye and six months later in the right eye. The treatment improved her vision in both eyes. Answer the following sub-questions separately.

1. Which corneal disease did Ms Duffy develop? (1 mark)

2. What could be the effect/s of this corneal disease on Ms Duffy’s vision and why? (1 mark)

3. What are the two most common likely causes of this disease? (1 mark)

4. From your understanding of the structure of the cornea, state primarily which part/s of the cornea is/are compromised in this disease? (1 mark)

5. What are the main clinical and histopathological features of this disease?

6. Which pathophysiological mechanisms are activated in this disease? Explain three of the mechanisms.

7. Explain the basic principle underlying treatment of Ms Duffy’s disease. (1 mark)

Answer 1

Ans 1) Keratoconus is a condition which is a corneal that causes thinner and steeper cornea as compared to normal corneas. This causes an abnormal shape in the cornea and hence the light is not able to focus properly on the cornea and hence tends to cause blurriness in vision. The most common symptom for the same is the blurriness in the vision. The cornea bulges towards the outside and forms a cone shape and gradually thins out. It also causes cloudiness in the vision.

Ans 2) The effect of this corneal disease is that it causes blurriness of the vision due to the bulging and thinning of cornea. The light that falls in the cornea is not able to focus properly causing the cloudiness. Apart from that it also tends to cause sensitivity to light and glare along with distorted vision. It tends to even cause nearsightedness.

Ans 3) Two most causes of the disease are:-

i) The first reason is weakening of the collagen fibres which helps in holding the cornea in place. When these fibers become weak, they are not able to hold the cornea in place and hence it tends to bulge out and become cone shaped.

ii) Apart from that increase in the concentration of protective antioxidants in the cornea area is another cause and due to exposure to free radicals, it tends to damage the cornea cells. The anti-oxidants protect the collagen and without that the collagen weakens bulging out the cornea.

Ans 4) The front and middle part of the cornea is destroyed and damaged during the condition which leads to its gradual thinning as well as bulging out. As it is not able to focus light, the vision becomes blurry and distorted.