Our eyes are one of the most complex organs of our body. They rely on three different layers and more than two million components to make our eyesight possible.
The first layer - and also the outermost layer - contains the cornea and the sclera. The sclera is a thin, fibrous yet tough structure that acts as a shield, protecting your eye's more fragile components within. Together with the cornea, the transparent front surface of the eye, it protects your eyes from bacteria, dirt and other harmful particles.
The second (middle) layer is comprised of the blood vessels providing oxygen and nutrients to those tiny muscles that move the lens.
The third and innermost layer is called the retina, a superfine structure with millions of light-sensitive cells, receptors, and neurons. These cells connect with the nerves passing the light signals to the brain.
Receptors and Neurons
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Photoreceptors are part of the retina and are classified into tapered cone cells and blunt-ended rod cells. The tapered cone cells are responding to bright light while the rod cells are extremely light sensitive and respond well to dim light. Protein-based photopigments that are contained in the receptors absorb different colors as different light waves which is the foundation for our eyes to see. The diameter of a human eye is about 25mm or about one inch. Our tears keep the cornea moist and a watery, aqueous lubricant on the inside keeps the lens moist on all sides.
Blurry vision caused by unfocused projection through the cornea and lens to the retina.
Refractive ErrorsThe most common conditions are near- and farsightedness, astigmatism and presbyopia. In most cases they can be corrected using:
- Glasses have been around for centuries and are still a very popular choice to correct bad eye sight.
- Contact lenses are getting increasingly popular, especially since the arrival of daily silicone hydrogel lenses.
- Refractive surgery using laser technology
Occurs when the intraocular pressure increases - caused by an increase of the jellylike substance inside the eyeball.
GlaucomaBlurry vision that is caused by an increased interior eye pressure, damaging the optic nerve system.
- Did you know, that glaucoma is the second leading cause of blindness?
- Health conditions, medical history, age, ethnicity and family history are important glaucoma risk contributors.
Often found amongst the elderly population, this condition stems from a cloudy lens and typically results in a vision with halos.
CataractA cataract develops over a long time and is caused by proteins building up within the lens. And with a cloudy lens, clear images cannot get through to the retina where they get processed and send to the brain. More than 50% of the US population will have a cataract by the age of 80. Treatment options include:
- Surgery: The protein clumps can be broken up and removed by using ultrasound waves - a procedure also known as phacoemulsification.
- A healthy diet, active lifestyle, normal weight and protecting your eyes from UVB rays can keep a cataract in check.
Blurry vision caused by damaged cells in the macular area of the retina. Most commonly found in people of age 60 and older.
The most common form is dry macular degeneration (MD) caused by tiny yellow particles (called drusen) building up under the macula. As with other eye conditions, a healthy lifestyle is important for preventing MD and age-related MD.
Unfortunately, there is currently no cure but vision therapy is an option to manage and cope with vision loss. Another option is surgery by implanting a magnifier lens.
Have you ever heard the term 'lazy eye'? This condition is most commonly found in children of age 6 and younger.
AmblyopiaThis vision disorder affects primarily children in early childhood development. Often affecting one eye only, it can be caused by several interfering conditions: Irregular shape of the cornea, a cloudy lens, improper eye alignment.
Often combined with dedicated eye exercises, treatment options focus on training the lazy eye and include:
- Eye patch to cover the good eye
- Atropine eye drops to blur the good eye
Caused by diabetes, the tiny blood vessels can no longer nourish your retina. This can cause blindness and - at an earlier stage - dark spots.
Diabetic RetinopathyThis condition affects around 80% of diabetics with a 20 year or longer diabetic history. It is the result of damage to the small blood vessels that are very vulnerable to poor blood sugar levels. The reduced retinal blood flow damages cells and neurons resulting in blurry vision first and black spots later. Early treatments have a high chance of success limiting vision loss. Treatment options include:
- Laser surgery (photocoagulation)
- Special medications
- Vitrectomy surgery