Hipótesis Específicas 01

The important structures around the eye all begin with the letter L—lids, lashes, lacrimal system, and lymph nodes. These are usually the first things checked after the visual acuity, visual fields, and refraction have been completed.

Are the eyelids swollen? Is the upper lid droopy? Is the eyelid skin red- dened? Many ocular conditions affect the eyelids. Blepharitis, a very common

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inflammation of the eyelids, can cause all of these problems. A scratch on the eye may make the upper eyelid droop a little. Styes and their close cousins, chalazia, cause reddened bumps. Tumors of various kinds may form on the lids. An overactive thyroid gland may cause the eye to open more widely. Medications may affect the lids. Foreign bodies may lodge under the upper lid. Eyelids may turn in or out, causing uncomfortable symptoms. All of these as well as other problems are usually evident at the start of the examination.

What do the lashes look like? Some eyelid conditions, such as blepharitis, can make the lashes fall out or turn white. Some eyedrops can make the lashes darker and thicker looking. Misdirected eyelashes, the result of scarring from infections or injury, may scrape the surface of the eye.

The lacrimal system is concerned with the production and drainage of tears from the eye. Any swelling in the area of the lacrimal gland, which is located above the eye toward the temple, must be noted. An enlarged lacrimal gland may give the contour of the upper lid an S-shaped appearance. Swelling in the area of the lacrimal sac, which is located between the eye and the nose, must also be detected. Sometimes we press on the skin over the lacrimal sac to see whether pus can be expressed through the small openings (puncta) in the eye- lid margins. Someone in whom the tear drainage system is blocked will have a teary eye, and the tears will often run down the cheek, a condition called epiphora. This is sometimes present in newborns whose tear (nasolacrimal) ducts haven’t fully opened or in adults whose tear ducts have shut down.

The lymph nodes are bits of tissue that help the body fight infection. They enlarge greatly and even become tender with some types of infection. When an eye infection is present, we try to determine whether the lymph nodes have become enlarged. The preauricular lymph node is located right in front of the ear and receives drainage primarily from the upper eyelid on that side. The sub- mandibular lymph node is located just beneath the angle of the lower jaw and receives drainage primarily from the lower eyelids. Lymph nodes may also become enlarged when they become infiltrated by cancer cells.

Motility (Eye Movement)

In this part of the examination, we make sure that both eyes move well in all directions, both individually and as a pair. We check the straightness of the eyes, both at distance and at near. When one of the nerves coming from the

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brain is malfunctioning, this testing can often determine which nerve is the problem. In some people, the eyes are straight when both are being used, but when one eye is covered, it wanders a bit. This can sometimes explain a per- son’s unusual symptoms. Further testing, such as fusion (ability to use the eyes together) and stereopsis (depth perception), is done in special cases, especially in children with eye straightness problems.

Pupils

Testing the pupils is part of every routine eye examination. We examine the pupils for their size, shape, and the way they react to light. We keep the room illumination dim and have the patient look at a target across the room. Then we shine a small light from below toward the eyes to compare them. We then shine the light more directly into each eye to see whether the pupil becomes smaller (constricts), as it should. Patients should not look directly at the light as this is done, as the simple act of looking at something up close also makes the pupils constrict. Then we perform the “swinging flashlight test,”in which the light goes back and forth between the two eyes. In a person with an optic nerve disorder, the pupil may enlarge a bit when the light is swung over to that side.

Pupils come in widely varying sizes, but there shouldn’t be a large differ- ence between sizes of a person’s two pupils. Some people are born with such a difference, but usually one of a variety of problems, from previous eye surgery or injury in an eye to inflammation, causes a size difference. For example, an eye with inflammation inside of it (iritis) may have a pupil that is smaller than that in the other eye. Sometimes a small, distorted, or unreactive pupil is the result of scarring caused by previous cataract or other surgery inside the eye. A blunt injury to an eye may cause tears in the little muscle of the iris sur- rounding the pupil, resulting in a larger pupil that does not react well to light. Some medications can also affect the size of the pupils. Of course, there are many unusual problems that can affect the size of the pupils as well.

As just mentioned, the pupils usually become smaller when you focus on something up close. When someone’s pupils do not constrict normally when light is shined into them, we usually check to see whether they constrict with near focusing. A number of problems, including diabetes and syphilis, can cause the pupils to react with focusing at near but not when a light is directed at them.

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