We probably have heard that the eye is the window to the soul. Literally, our eyes also have a lot to say about our bodies. The expression in our eyes may reveal our emotional state however hard we try to hide them. The condition of the eye is also a reflection of the state of the body. Many systemic disorders like endocrinology diseases and heart diseases have specific ocular manifestations. Recent research studies have shown that signs of neurodegenerative diseases such as Alzheimer’s disease can also be seen in the eyes.
Next to the brain, the eye is the most complex organ of the body. The eye can be described as an organ of light sensitivity that consists of different parts that synchronize to give us sight. Anatomically, the eye broadly consists of the conjunctiva, sclera, cornea, iris, pupil, lens, vitreous, choroid, and retina. The retina further consists of the optic nerve and macula which houses the fovea.
Vision process
Light from an object is focused by the cornea and the iris regulates the pupil size to control the amount of light that passes through the eye. The lens then refracts the light unto the retina and the retina transmits light signals through the visual pathway to the brain for interpretation. The retina is a sensory tissue with several layers one of which contains highly specialized cells called photoreceptors that respond to light stimulus.
We have two types of photoreceptors- the rods and cones. Rod cells are mostly found concentrated at the periphery of the retina and they help us see in dim light, detect motion, and provide peripheral vision. The cones are concentrated in the fovea which is a small pit on the macula. The cones function well in bright light and are responsible for providing color vision and central vision.
The eye has a rich supply of oxygen and nutrients through its blood vessels. The main blood vessels of the eye branch out to form small, tiny blood vessels known as capillaries.
All the different parts of the eye work in harmony to help us see. Abnormalities to any part of the eye can lead to vision loss. For example, an opaque cornea will prevent light from entering the eye to the retina and obstruction to the supply of blood in the retina may lead to defects in the visual field.
Some common conditions that affect the eye
Stress: Stress-related eye problems include dryness, twitching, floaters, glare, eye aches, and so on. Chronic exposure to stress may affect the immune system and reduce blood supply to the retina.
Diabetes: This metabolic problem may cause vision loss. Sharp changes in the blood sugar levels can change the shape of the lens and cause temporary blurry vision that returns to normal on reaching a stable blood glucose level. Also, individuals with diabetes are more susceptible to developing cataracts. Other diabetes-related vision problems include diabetic retinopathy and macula edema.
Age-related macular disease (AMD): AMD is a loss of central vision due to degeneration of the macula. The macula contains the fovea that consists of cells used for central vision and color vision. Apart from the diminished central vision, visual distortions such as wavy lines, poor dark adaptation, and difficulty reading may occur. AMD is a leading cause of visual impairment in the elderly population. Some risk factors include Caucasian, family history, and smoking.
Hypertension: High blood pressure may damage the capillaries that supply nutrients to the retina leading to hypertensive retinopathy. Damage to the blood vessels may lead to bleeding in the retina and visual field loss due to damage to the optic nerve. If left untreated it can lead to severe vision loss or blindness.
Sjogren’s syndrome: This is an autoimmune disorder identified by dryness of the eyes and mouth. Here the immune system attacks the glands that produce tears and saliva. The inflammation of the glands leads to decreased tear production that results in extreme dry eyes. Dry eyes may cause discomfort, grittiness, itchy, redness, burning sensation, and excessive blinking to alleviate the discomfort.
Multiple sclerosis (MS): MS is an autoimmune neurodegenerative disease of the brain and spinal cord. In the eye, MS usually causes unilateral optic nerve inflammation - optic neuritis. This may result in painful eye movements, involuntary eye movements (nystagmus) and double vision (diplopia).
Malnutrition and nutritional deficiency: Nutritional deficiencies may cause vision problems such as night blindness, blurriness, discoloration of the sclera, and dryness. For example, a deficiency in vitamin B-12 may cause puffy eyes, dark circles around the eye. Though rare, vitamin B12 deficiency may lead to optic neuropathy that presents with bilateral vision loss and decreased color vision.
Take Ownership
Maintain a healthy lifestyle and proper diet.
Know your stressors and manage them
Build a routine to care for your eyes https://www.junebrain.com/post/diy-eyecare
Schedule a visit to your eye physician
Be intentional, take care of yourself- you are a precious being!
Sources
Image of the eye
https://www.shutterstock.com/image-vector/vector-human-eye-engraved-style-eps8-227164972
Image of the retina
https://www.frontiersin.org/files/Articles/623725/fimmu-12-623725-HTML/image_m/fimmu-12-623725-g001.jpg