How do we see?

The eye is the organ of the sense of vision. It is formed as a balloon with different layers, each of which has a function, which allow light to penetrate up to the retinal inner layer of the eye, consisting of nerve endings that can detect light, its intensity and color and transform it into nerve stimulation. This nerve stimulation is conducted by the optic nerve to the brain area (the posterior or occipital lobe of the brain) where it is translated into an image..

The light passes through the cornea, a transparent dome-shaped layer covering the front of the eye, into the pupil, which is more or less wide depending on the amount of light that is receiving the eye and reaches the lens. The crystalline lens is a lens to focus light or image on the retina.

The combination of the images to the brain from the two eyes allw us to see in three dimensions (three-dimensional vision), with volume and perspective. It is important to understand that we actually "see" in the brain, but, in order to see, it is necessary to see the light and the images come in the form of nerve stimulation to the brain, and for that, we need the eyes.

Therefore, it is explained that there are blind people, for example after an accident with injury to the brain in the occipital area, which have intact eyes. Or in the other side of the spectrum, a blind person because the cornea has become opaque by accident, this person can see again after a corneal transplant.

What are the most common vision problems?

Vision problems may be due to defects in the shape of the eye, resulting in the so-called refractive errors which are corrected with glasses, and those due to faulty irrigation, eye presure, the function of the elements of eye or changes in the retina and / or optic nerve, and in many cases are secondary to systemic diseases such as diabetes.

  • Defects in vision, refractive errors:
    • Myopia: difficulty seeing distant objects.
    • Hyperopia: difficulty seeing near objects.
    • Presbyopia: difficulty focusing, due to the aging of the lens. Started between 40-50 years. A typical symptom is the need to place the book or newspaper ever further from the eyes to see the letters well.
    • Astigmatism cornea has no uniform round shape, so that the objects are deformed. Often accompanies myopia or hyperopia. Refractive errors are corrected by prescription lenses.
  • Diabetic retinopathy
  • Macular degeneration
  • Glaucoma
  • Falls

How you can correct vision problems?

Visual problems due to defects in refraction are corrected with corrective lenses, that are glasses or contact lenses. Secondary issues to diabetic retinopathy require strict and careful diabetes control and treatment of vascular eye injuries. Cataracts may require surgical intervention in advanced stages. Laser therapy is useful to treat or slow the progression of retinal lesions associated with many ocular diseases. In many of them wearing glasses can help improve vision.

How can we prevent injuries and accidents that affect the eyes?

1.- Regular ophthalmologic checks

One of the first things to consider is the periodic monitoring of visual acuity and the eye itself. Thus, within the medical examinations during infancy, the pediatrician, by keeping a history and control of visual acuity, can detect early vision problems. Also people must look for a doctor to check for problems in visual acuity, abnormal vision, eye pain, etc. The recommendation of periodic reviews is particularly important in diabetic, hypertensive or have any people with eye diseases.

Using these controls you can detect early lesions, visual acuity problems, or diseases that may allow early treatment to reduce vision loss.

Eye examinations include the study of fundus, visual acuity, visual field and the determination of eye internal presure. For the study of the fundus is necessary to dilate the pupil, which is done by applying a drug called mydriatic eye drops (which produce mydriasis or dilation of the pupil) to the eye.

Through the eye pupil we can study the retina and the vessels thereof, identifying the lesions of diseases such as diabetic retinopathy, macular degeneration, or retinal detachment, among others. Using a tonometer that is placed over the cornea, the ocular tension, important in the diagnosis and management of glaucoma, is measured.

Through testing the ability to see letters or drawings at a controlled distance, of different sizes, or different colors, we check the visual acuity and color vision, allowing to diagnose different types of visual acuity problems (nearsightedness, farsightedness, astigmatism, blindness, etc.)

Finally, checking for side vision detects any reduction or deterioration of the visual field associated with diseases such as glaucoma or retinal lesions associated with diabetic retinopathy, retinal detachment, etc ...

2.- Adoption of protective eye wear

Accidents and eye injuries require protection measures during activities in the sun, the workplace, during sports, and during activities in which particle emission occurs, risk of shock or impact of particles or splashing of contaminated body fluids..

In the workplace, it is essential that a security policy must be based on the correct design of the workspace, in the placement of tools, chemicals, machinery, technical equipment, etc., as well as give proper training to workers.

Possible risks must be identified, and workers and health service professionals must be trained in prevention and response in case of accident. For example, in a laboratory, all workers must know the chemical and biological products used, their proper handling, safety standards and how to react in case of accident and have always accessible MSDSs for these products in the workspace for easy reference in case of accident.

A key resource is the availability of visible emergency phone for consultation or care.

Showers and eyewash should be available as wel as kits with isotonic saline and bandagings.

The second thing to keep in mind is the availability and use of systems to protect eyes and face appropriate to the tasks and risks. Eye protection devices must meet CE standards and quality. It is important to systematically check their condition and operation (safety glasses with cracks in the lenses would be useless, for example), the type of glasses or goggles that requires the activity to be performed must be selected (carving, welding etc.), and SHOULD ALWAYS BE USED !!!!

What should be done before an eye injury or accident?

The most common eye injuries are the impact of a foreign body (splinter of wood or metal, stone chips ...); punctures or cuts; Chemical products splash and shock.

Given the impact of a splinter or foreign body you should wash the eye with plenty of water, avoid rubbing the eye, as by rubbing all that is done is to stick more splinter and injure the conjunctiva. If by flushing the eye no foreign body is removed, pain and redness persists, you should visit an ophthalmologist.

Do not use eye drops for eye wash or to treat the wound that is not medically indicated.

In case of cut, puncture, or if you have an object stuck in the eye, you should go immediately to the emergency room, avoiding eye manipulation. Do not wash or try to remove the stuck object, since it must be performed in the clinic under control. Protect the injured eye without oppressing, making a rigid camera.

Injuries from chemical burns usually consist of irritation. It is very important to thoroughly wash the eye with water for over 15 minutes and keep the eye moist, until we arrive to a urgent medical consultation. If the injured person wears contact lenses should not be handled, but wait for then to jump due to the washing effect.

In case of concussion, it is advisable to apply a cold compress or ice. You have to check for ocular bleeding, altered vision or pain, in which case you should go to the doctor.

Eye care: myths and realities

Reproduced from the National Eye Institute of the US

Myth: Reading with little light hurts your eyes.
Fact: Reading in dim light tires eyes, is not harmful.
Myth: Using Computer damages vision.
Fact: Although computer use is associated with eyestrain, does not damage the eyes.
Myth: If you read too much, her eyes are spent.
Fact: The eyes do not spend, you can use as much as you want.
Myth: Sitting too close to the TV is bad for the eyes.
FactThere is no scientific evidence that sitting close to the TV is bad for the eyes.
Myth: If you need glasses, is that your eyes are not healthy.
Fact The need to use lens has nothing to do with the health of the eyes, but with the size or shape of the eye, or due to changes in the eye associated with aging.
Myth: No need to be tested for the eyes until 40 or 50 years.
FactThe eye disease may occur at any time. As we age, is more common for eye diseases to develop.
Myth: Eating too many carrots is good for the eyes.
FactGood nutrition is important for overall health, including the eyes. The only basis for this myth is that carrots contain vitamin A which is needed in small amounts for proper functioning of the eyes, but a balanced diet contains all the vitamin A that a person needs. It must be noted that an excess of vitamin A can be harmful.