Case studies Changes in eyesight Gemma, a 52-year-old nurse, went to see her opt
ID: 3522007 • Letter: C
Question
Case studies Changes in eyesight Gemma, a 52-year-old nurse, went to see her optician as she was having problems reading Gemma had noticed that she had to hold her book at arm's length in order to be able to focus on the text. She had no problem reading road signs or other text at a distance. 1. What happens to the shape of the lens of the eye to enable us to focus on objects that are close to our eyes? 2. What happens to the shape of the lens of the eye to enable us to ocus on objects that are far away from our eyes? 3. How are the changes to the shape of the lens of the cye brought about? 4. Based on the symptoms described, what is Gemma's lens no onger able to do? Explain your answer.Explanation / Answer
Gemma has developed a condition possibly called as hypermetropia or farsightedness.
1:- Hypermetropia occurs when the eyeball length is short relative to the focusing power of the cornea and lens, or the lens is thinner than normal, so an image converges behind the ratina. The least distance for clear vision becomes larger than 25cm. It can be corrected by two methods either by the use of biconvex lens or glasses and by surgical method.
2:- Myopia or nearsighted is the condition which makes a person unable to focus on distant objects. It occurs when the eyeball is too large relative to the focusing power of the cornea and lens, or when the lens is thicker than normal so the image converges in front of the ratina. It can be corrected by two methods either by the use of biconcave glasses or lens and by the surgical methods.
3:- Tiny fibers of protein in the eye called collagen help hold the cornea in place and keep it from bulging. When these fibers become weak, they cannot hold the shape and the cornea becomes progressively more cone shaped. This condition is called keratoconus.
Keratoconus is caused by a decrease in protective antioxidants in the cornea. The cornea cells produce damaging by-products, like exhaust from a car. Normally, antioxidants get rid of them and protect the collagen fibers. If antioxidants levels are low, the collagen weakens and the cornea bulges out.
Keratoconus appears to run in families. If you have it and have children, it’s a good idea to have their eyes checked for it starting at age 10. The condition progresses more rapidly in people with certain medical problems, including certain allergic conditions. It could be related to chronic eye rubbing.
4:- Gemma's lens is unable to form image on ratina. The image formed is far from the ratina the hence she should use biconvex lens to focus the image on the ratina by converging the incident ray.
Hopefully answered your question efficiently. Please do review.
Thanks.