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Sensory system: Eye and ear disorders

Notes

Transcript

Content Reviewers:

Lisa Miklush, PhD, RNC, CNS

Eyes and ears can be affected by many diseases, which can be caused by infections; uncontrolled high blood sugar, like in diabetes; or simply by aging. We’ll be talking about some of the common eye and ear diseases that you may encounter when caring for clients.

Okay, let’s start with eye disorders. First is conjunctivitis, commonly known as the pink eye. It’s an infection of the thin membrane that lines the eyelids and covers the sclera, called the conjunctiva.

Clients with conjunctivitis will have pink or red eyes, itchiness or a burning sensation in their eyes, and watery or sticky discharge.

Conjunctivitis is really contagious as microbes can be easily transmitted from someone’s eyes to their hands and then to surfaces, where they’re picked up by another person. The most common treatment is prescribed eye drops or ointments.

Okay, next is glaucoma, which is when the aqueous humor in the anterior chamber of the eye builds up, causing an increase in the pressure inside the eyes.

This causes compression of blood vessels and nerves, which initially leads to blurred vision and peripheral vision loss as if the client’s looking through a tunnel.

If not treated, it can lead to complete blindness. Glaucoma is more common in people over the age of 40, and it’s more common in those with a family history of the disease.

It can be acute, where the client will suddenly have severe eye pain, vision loss, and nausea and vomiting. When it’s chronic, vision loss develops gradually over time.

There’s no cure for glaucoma, but medicated eye drops can help keep the pressure within the eye normal.

Okay, now the lens and cornea are both transparent, round structures that help to focus light entering the eyes on the retina, which allows us to see a clear image.

Now, any problem with focusing the light on the retina leads to refractive errors, which include myopia, hyperopia, presbyopia, and astigmatism.

Myopia occurs when the eyeball is more oval than normal, and this causes the distance between the lens and the retina to be larger.

So, when the client looks at a distant object, the light will focus in front of the retina instead of on it, and the client sees a blurry image. Myopia is also called nearsightedness because the client can see near objects clearly.

Now, hyperopia is the opposite of myopia. The shape of the eye causes the lense to be closer to the retina than normal, so when the client looks at a near object, the light will focus behind the retina instead of on it, causing the client to see a blurry image. Hyperopia is also called farsightedness because the client can see distant objects clearly.

Alright, some older clients may have presbyopia, where the lens becomes less flexible, so it loses much of its ability to change shape.

So, when the client looks at a near object, like when reading a book, the lens can't bend enough to focus the light on the retina. So the end result is that close objects appear blurry, just like with hyperopia.

Alright, the next refractive error is astigmatism. Now, normally light coming through the different parts of the cornea and lens are uniform.

In astigmatism, either the cornea or the lens have an abnormal shape, so light bends differently when entering from different parts of the eye.

So, this means the image isn’t perfectly focused on the retina, which leads to a blurry image. This holds true for both near and far objects.

Now, the treatment for refractive error includes the use of corrective lenses, like glasses or contact lenses, which help to focus the image onto the retina.

Alright, moving onto cataract. This is when the transparent lens develops cloudy and opaque areas that reduce the amount of light that passes to the retina.

The result is that the client sees a cloudy, unclear image. It also decreases night vision, and they may see a halo when looking at lights.

If left untreated, cataracts can eventually lead to blindness. The common causes include prolonged sunlight exposure, diabetes, smoking, and excessive alcohol use. The treatment is surgery, where the cloudy lens is replaced with another clear plastic lens.

Okay, moving to diabetic retinopathy. This occurs in clients with longstanding and uncontrolled high blood sugar, or diabetes. In these clients, blood vessels in the eye become leaky, causing tiny hemorrhages in the retina.

The client may see moving spots or streaks floating in their visual field, and if not treated, it can lead to blindness.

Treatment for diabetic retinopathy starts with keeping blood sugar under control. Laser surgery may be performed to seal off the bleeding vessels and stop the hemorrhage.

Macular degeneration involves the macula, which is a small oval spot in the retina that is responsible for the sharp, clear image we see when looking directly at something.