The Sense of Sight
The phrase “the eyes are the windows to the soul” is often used to express the depth of connection one feels while looking into another person’s eyes, as they can reveal one’s emotional state. Our eyes are crucial to our existence. They enable our sense of sight, thereby allowing us to observe and interpret the world around us. Simply put, the eye receives light from the environment, transmits visual information to the brain, and allows a person to interact with their environment safely. Preservation of mental acuity, sight, and vision is therefore crucial.
Sight and vision are complementary and vital to daily life, but they are distinct concepts. Sight, on one hand, refers to the sensory experience of the eyes concentrating light as it bounces off shapes and objects, the transmission of signals to the brain, and the development of images. On the other hand, vision is a metaphysical concept that defines how the mind perceives images and allows a person to perceive meaning and draw conclusions from an event.
How the Eyes Work
All components of the eye work together to enable sight. Light enters the eye via an aperture known as the pupil and the cornea (the transparent front layer), which bends light to help the eye focus. The iris (the coloured component of the eye) regulates how much light enters the pupil. The light then goes through the lens (the transparent innermost component of the eye), which works with the cornea to focus light on the retina properly. When light reaches the retina (a light-sensitive layer of tissue at the back of the eye), photoreceptors (rods and cones) convert light into electrical signals. These electrical signals flow through the optic nerve from the retina to the brain, where they are converted into the signals and images a person sees.
Prevalent Ocular Diseases in the Caribbean
In the Caribbean, the leading causes of blindness are glaucoma, cataracts, and diabetic retinopathy (a complication of diabetes).
Glaucoma is a group of eye diseases that can result in vision loss and blindness by damaging the optic nerve in the back of the eye. Glaucoma often presents no symptoms at first. It is known as “the silent thief of sight” because people with Glaucoma are often unaware of the condition, necessitating annual screening. Persons affected by this disease may gradually lose their eyesight, generally beginning with their peripheral (side) vision. It develops so gradually that many individuals are unaware that their eyesight has changed at first. However, as the condition progresses, people may realise they can no longer see objects off to the side. Glaucoma, if left untreated, may lead to blindness.
Risk Factors for Glaucoma
- Age: People over the age of 60 years and individuals of African descent over the age of 40 years are at increased risk of developing glaucoma, and the risk of glaucoma increases slightly with each year of life.
- Race: Compared to other races, persons of African descent are significantly more predisposed to experience glaucoma and suffer permanent vision loss.
- Family history: Having a family history of glaucoma increases the risk of developing the condition.
- Medical conditions: Findings from studies indicate medical conditions such as diabetes, high blood pressure, and heart disease may increase vulnerability to developing glaucoma.
- Physical injuries to the eye: Severe trauma, such as being hit in the eye, can cause internal damage, which may result in immediate or later increased eye pressure.
- Other eye-related risk factors: Conditions such as thin cornea and increased optic nerve sensitivity, retinal detachment, eye tumors, eye inflammation, and high Myopia may increase the risk of developing glaucoma
- Corticosteroid use: Prolonged use of corticosteroids (including cortisone, hydrocortisone, and prednisone) for prolonged periods appears to put some people at risk of developing secondary glaucoma.
Myths and Facts about Glaucoma
Myth: Glaucoma testing is painful.
Fact: Testing for glaucoma is painless
Myth: Glaucoma only affects the elderly
Fact: Some types of glaucoma can affect people between the ages of 20 – 50 years
Myth: People with glaucoma experience obvious symptoms
Fact: Most people with glaucoma have virtually no symptoms or signs until the later stages
A Cataract is a cloudy area in the lens (the clear part of the eye that helps to focus light) of the eye. Cataracts may result in blurry, hazy, or less colourful vision and are very common as a person advances in age. Initially, an individual may experience trouble reading and completing other daily activities, and vision loss can occur if cataracts are untreated. The good news is that cataracts can be surgically removed safely to correct vision problems.
Risk Factors for Cataract
The risk of cataracts increases as a person advances in age. Additional risk factors include:
- Health conditions such as diabetes
- Smoking
- Consumption of too much alcohol
- A family history of cataracts
- History of eye injury, eye surgery, or radiation treatment to the upper body
- Extended exposure to the sun
- Use of steroids and some medications used to treat health challenges, like arthritis or allergies.
Myths and Facts about Cataracts
Myth: Cataracts must be “ripe” to be removed
Fact: With modern surgery, cataracts can be removed before they mature, particularly if they are presenting challenges in conducting daily activities.
Myth: Cataracts are removed with lasers
Fact: Cataracts cannot be removed by laser but by surgical incision. After surgery, a laser may be used to open a membrane that may become cloudy during surgery.
Diabetic Retinopathy is caused by high blood sugar due to diabetes. Over time, too much sugar in the blood can damage the retina and blood vessels all over the body. Damage to the eyes begins when sugar blocks tiny blood vessels connected to the retina, causing them to leak fluid or bleed. To replace blocked blood vessels, the body develops new blood vessels, which malfunction by also leaking and bleeding.
Risk Factors for Diabetic Retinopathy
- Individuals with any type of diabetic condition (including type 1, type 2, and gestational diabetes) are at risk of developing diabetic retinopathy.
- Risk increases with prolonged exposure to diabetes, and projections indicate more than half of people with diabetes are likely to develop diabetic retinopathy. However, the risk of developing diabetic retinopathy can be lowered by effectively managing diabetes.
- Pregnant women with diabetes, or women who develop gestational diabetes, are at higher risk of developing diabetic retinopathy.
Myths and Facts about Diabetic Retinopathy
Myth: Laser treatment for diabetic retinopathy can lead to blood sugar control and proper management of diabetes.
Fact: Like diabetes, diabetic retinopathy is an ongoing condition that requires ongoing management to control.
Myth: My vision is fine. I have no other symptoms. I don’t think I need a dilated retinal examination.
Fact: A person’s vision is usually unaffected unless the central part of the retina, called the macula, is affected.
Myth: I got my glasses checked recently; hence, I don’t need further eye check-ups.
Fact: The checking of glass power (refraction) is just a small part of the total eye examination. Many treatable conditions of the eyes may not get their due attention unless a thorough examination is done.
Pterygium
Though Pterygium is not a leading cause of vision loss, it is a common disorder of the eye that affects many people in the Caribbean. A pterygium is a fleshy excessive growth of the conjunctiva that may affect one or both eyes. Pterygium may develop from prolonged exposure to chronic irritants, such as the sun’s ultraviolet rays, and dusty or sandy conditions. Generally, a pterygium is painless, and symptoms may include:
- Inflammation, including bloodshot to the white of the eye where the pterygium is located
- Itching and burning sensations on the surface of the eye
- Mild eye pain
- Problems with vision if the pterygium grows across the cornea
Wearing UV-protection sunglasses and a wide-brimmed hat to protect the eyes from direct ultraviolet rays from sunlight may be beneficial in preventing the start or progression of pterygium.
Myths and Facts about Pterygium
Myth: Pterygia are just cosmetic and do not need to be removed.
Fact: Pterygia should be medically removed to avoid symptoms like burning, itching, redness, tearing, or a scratching sensation.
Myth: Pterygia always comes back, no matter what.
Fact: Recurrence, particularly in high-risk areas like warm climates, is a common challenge. The technique used during surgery minimizes recurrence, and protecting the eyes from the sun, dust, and wind is also crucial in averting recurrence.
Myth: Pterygium surgery is miserable and painful.
Fact: Surgery to remove the pterygium takes approximately 30 minutes, the eyes are numbed during surgery to prevent pain or discomfort, and recovery is relatively short, with most people resuming work about three days after surgery.
In part two, we will discuss guidelines for healthy lifestyles and care of the eyes to prevent and or manage common eye diseases.
