The principal function of the eyes is to enable you to see. This is not something unique to man alone; it is a widespread ability throughout the animal kingdom such that survival without having vision is, although not impossible, certainly makes life and safety much more challenging. The various parts of the eye work in tandem to allow people to see.

Basically, the eyes take light in from the environment around us and send that information to the brain for processing. Therefore, vision is a very complex process that involves the different parts of the eye working together in concert with the brain so that individuals can appreciate their environment, maintain their balance, avoid danger and navigate their way safely wherever they go.

Other secondary properties of vision that have to do with reading and writing are essential for the development of the intellect and the dissemination of knowledge. Many people develop vision problems which are eminently treatable, such as cataracts, but would cause blindness if not treated.

Eye-related symptoms often indicate a serious underlying health condition, and sudden changes in vision like blurred vision or an increase in floaters suggest a need for medical care. When there are significant concerns about the clarity of vision, such a person should seek to be examined by an ophthalmologist.

The only part of the eye that most people can see is the front of the eyeball. The rest of it is inside the eye socket. Within that socket are various muscles which move the eyes in the direction of a person’s gaze.

The eye has different types of tissues in it. The first group is made up of refracting tissues which are sensitive to light and work to give a person a clear, sharp image of objects. If those tissues are wrongly aligned, have the wrong shape or have suffered any form of damage, the vision becomes blurred.

These structures are the pupil, the iris, the cornea, the lens and the ciliary muscles. The pupil is the dark spot in the centre of the eye, which can shrink or grow larger in response to light, and is surrounded by the iris, which is made up of the muscles that help regulate the amount of light that can enter the eye and eventually reach the retina at the back of the eyeball.

This action makes it similar to the shutter of a camera. After light passes through the pupil, it goes to the lens which is a transparent, flexible structure that helps to focus light accurately onto the lens.

As a person ages, this flexibility is progressively lost and focusing becomes more difficult. The other refracting tissue there is the ciliary muscle, which can contract or relax, thereby changing the shape of the lens in real time in a process known as accommodation.

Then, there is the cornea, a clear layer of tissue that covers the pupil, iris and anterior chamber, which is a fluid-filled recess between the cornea and the iris. The cornea provides a protective role for the eyeball by shielding it from injury and contamination with foreign materials such as dust.

It is a very sensitive tissue full of nerve endings but no blood vessels, so that it can remain clear to properly refract light. Part of the refractive eye tissue is the fluids present in the eyeball. There is the vitreous humour, which makes up the bulk of the volume of the eyeball. It is like jelly, and the loss of this fluid leads to the collapse of the eyeball.

The other, lesser fluid is the aqueous humour, which is found in the front of the eye. Then, there are the light-sensitive tissues mainly made up of the retina and the optic nerve. The retina is the innermost layer of the eye and contains millions of photoreceptor cells that detect light and convert it to electrical signals, which it sends to the brain for processing.

The two primary photoreceptor cells in the eye are called rods and cones. Cones are present in the central part of the retina, called the macula, and the retina has up to six million of these cells. Within the macula is the fovea, a small pit in its centre that contains most of these cones but has no rods. Cones are important for helping to distinguish colours.

This helps people see properly in normal light conditions, and there are different schemes corresponding to red, green and blue, with the blue cones mostly outside the centre of the fovea. On the other hand, rods exist mostly at the edges of the retina and are responsible for black-and-white vision.

Rods can detect the lowest amount of light and so enable people to see at night. The other light-sensitive tissue is the optic nerve, which is a thick bundle of nerve fibres that transmits light signals from the retina to the brain.

It leaves the eye at a point called the optic disc, where there are neither rods nor cones, and is called the blind spot. This terminal part of the communication between the optic nerve and the brain is maintained by ganglion cells, which are sensitive to different things such as shape and detail or contrast and movement, but all of which work together to carry the necessary information we need to build an image from our field of vision.

Lastly is the brain, which coordinates the visual signals from both eyes to create images. Lastly, there are particular kinds of support tissues that the eyes cannot do without. They are the sclera, which is white and supports the structure of the eyeball because it is fibrous and attached to muscles.

Next is the conjunctiva, which covers the sclera; it is thin and can get infected. The last of these is the uvea, which supplies blood to the eye and is the middle layer of the eyeball. The iris, ciliary body and choroid are part of this layer.

A wide range of eye conditions can affect your eyes. Some of these factors are due to genetic problems and are therefore some of the issues that a person would be born with. Other conditions are due to age, while the rest are often found in association with other health conditions such as diabetes, injury to the eyes and damage from ultraviolet irradiation.

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Questions and answers

Sunday Doctor, please, my wife delivered a child through a Caesarean section in a private hospital in June 2025, and after five days she died. The excuse the doctor gave was that she did not fart after the operation. My wife has been buried since June last year, but can I sue the hospital or the doctor for negligence?                             Tay*******

 The problem with a case like this is the ability to prove negligence. Early action soon after the demise of your wife might have yielded important evidence to support or refute your allegation, but now, after more than 16 months, much of that evidence would be irretrievable in our setting. There is no need to pursue this, as legal processes can be lengthy and frustrating as well, not to mention the cost of pursuing that avenue to seek redress.

Sunday Doctor, people who have just undergone abdominal surgery, e.g. Caesarean section or myomectomy, are often told not to carry more than 3 kg (equivalent to 3 litres of water) to start with. Does the passage of years allow heavier loads to be carried? When is it safe to lift a 16 kg bucket of water or a child older than six months?                                                                      081*******

Yes, the passage of time allows you to gradually increase the amount of load you can carry. The standard guidance is to avoid lifting anything other than your baby during the first 6 weeks. From about three months and beyond, you can gradually increase the amount of load you lift so that lifting a standard bucket of water or a 6-month-old baby should be possible after the third month. But not every woman is the same, and wound healing varies widely in different people.

Sunday Doctor, I was the one who told you about the use B-complex as an appetite stimulant. Within 1 week, I was able to eat some foods very well, like yam, eba and pap, but I can’t eat amala yet. My intake of rice and beans has also improved. But I can’t eat the foods that I have been so used to before now very well, but I can eat others that I was not so used to before. Maybe my age, 70 years, is the cause of the shift. Thank you, sir. God bless you.                                    0705*******

Congratulations, sir, on the progress made. You had used the B-complex for less than a week before observing these changes. With further usage, your appetite should improve well enough to include even the ones you are slow with now. However, advancing age is a factor in all of these.

Sunday Doctor. I am a 67-year-old man, and I am in good health according to my doctor. However, in the last five months or so, I have noticed that I urinate more frequently at night than before. At least a year ago, I used to urinate only once at night and at most twice, but these days it is four or five times. I wake up in the morning feeling tired, and I don’t understand why. I did a urine test and blood sugar test but the two were okay. What is your advice, doctor?                         081*******

At your age, sir, it is expected that your prostate would have increased in size significantly. It is possible that such an increase in size has been rapid over the last year, hence the sudden change in urinary habits. However, it is important that you go to a good hospital and have a proper examination to determine what is responsible for this. You should have a urine culture done, as well your blood glucose evaluation and ultrasound of your urinary system. Other specific blood tests would likely be required depending on what is found initially.

Sunday Doctor, good morning. DNA structure and chromosomes; are they the same thing? Please reply.                                                                                        0806******

Chromosomes are structures in the nucleus of cells containing DNA, which is found in all living things, without which we cannot survive, function and grow. Our DNA is made up of four different bases, which the cells in our body can read almost like a book, and so are able to produce all the different proteins we need. Long strands of this DNA make up the chromosomes, which are found inside the cell nucleus.

Sunday Doctor, good morning to you. My baby has heat rashes, and I was initially using Tribotan cream until a doctor told me it was heat rashes and that I should use dusting powder instead, and that it was not an infection. I have been applying it for two weeks now, and they are still there. What should I do?     0803*******

Well, heat rashes have no specific time frame to resolve. As long as the prickly heat conditions are present, the rashes will remain. So, this is not a drug that has a definite dosage and time to administer it; just keep applying the powder and make sure to keep the baby’s skin as dry as possible. To be certain, the conditions promoting such heat look set to worsen in the coming weeks.

Sunday Doctor, good afternoon.  Is it normal for a two-year-old child to stool once every two or three days?        0802*******

Yes, that is normal. Stools can be passed three times in a day or once every three days. Everything else in between these boundaries is normal. So, one motion every two days is fine, just like a motion every single day.

Source: Punch · Dr. Sylvester Ikhisemojie

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