Chapter 40, Problem 2Q

Summary Introduction

To review:

The hypothesis that have led to the results in table by the production of epinephrine.

Given:

Cataract in humans is a fatal disease that leads to loss of vision. It is caused by excessive exposure to ultraviolet light and also due to the age factor. There is cloudy appearance and non-transparency of the lens. The cataract has to be removed by the surgeon for the recovery of sight. For surgery, the surgeon makes sure that pupil is dilated properly and for a longer time. The dilation of the pupil is controlled by adrenal medulla which releases epinephrine and norepinephrine.

An experiment was conducted by the researchers to find if epinephrine can help in keeping the pupil dilated for a longer time during cataract surgeries. Epinephrine was injected into the eye of the 27 patients who came for cataract surgery but not injected in the eyes of other 43 other patients.

The following table depicts the percentage of patients whose eyes had the pupil diameter size less than five mm during the different stages of the cataract surgery.

The percentage of individuals having the diameter of pupil less than five mm

Introduction:

Pupil is a small opening in the iris which is surrounded by two types of smooth muscles. Light is perceived by the pupil and reaches the retina of the eye for image formation. Epinephrine is a fight fright and flight hormone which has the direct control over the contraction and relaxation of the pupil. The dilation of pupil by epinephrine increases its size while contraction reduces the size.