Why Do We Lose Our Eyesight as We Age?

Light enters through a transparent tissue in front of the eye called the cornea.

• The shape and thickness of the cornea determine how much the entering light rays will be bent and consequently focus on the light-sensitive tissue (retina) present at the back of the eye.
• Thus, corneal health is crucial to determine how well an image is focused on the eye.

After entering the cornea, the light passes through the tiny circular opening called the pupil, which is seen in the center of the colored part of the eye called the iris.

• The iris controls how much light enters the eye by changing the size of the pupil. 
• Thus, in bright light, the pupil appears smaller, whereas, in dim light, it becomes larger.

Light entering the pupil then passes through the lens which is a clear structure that further focuses the light. The thickness of the lens can be changed by the muscles attached to it. 

Finally, the light is focused on the retina that converts it to electrical signals that are carried to the brain through the optic nerve.

The inside of the eyeball is divided into three chambers: anterior, posterior, and vitreous.

• The anterior chamber is the part between the cornea and iris.
• The posterior chamber is between the iris and lens.
• The vitreous chamber is the part behind the lens.

Anterior and posterior chambers are filled with a watery fluid called the aqueous humor, whereas the vitreous chamber has a gel-like clear substance called the vitreous humor.

• The clarity and consistency of these humor or fluids help maintain the shape of the eyeball and achieve a proper vision.
• Thus, if any part of the eye gets affected, the final image processed by the brain may get affected, resulting in vision issues.

Different age-related vision problems include:

• Presbyopia:
  • Refers to the decline in the focusing ability of the eye due to a reduction in lens elasticity.
  • It may manifest after 40 years of age as difficulty seeing objects held close by or reading newspapers and other fine prints. It may occur sooner in people who already have myopia.
  • The person often holds books or other reading material at arm’s length to read properly.
  • Presbyopia can be managed by wearing reading glasses or bifocals.
• Cataract:
  • The opacification or clouding of the lens is called a cataract.
  • Opaque regions on the lens result in poor focusing of the light rays, resulting in diminished or blurry vision.
  • Vision changes are painless and depend on where on the lens the opacification occurs.
  • Cataracts can be easily treated through surgery that involves removing the opacified lens and replacing it with an artificial lens.
• Glaucoma:
  • A serious condition that occurs due to increased pressure within the eye (intraocular pressure or IOP). Persistently increased IOP can lead to permanent loss of vision due to optic nerve damage.
  • Glaucoma may present as severe eye pain, headache, blurring of vision, increased tearing, nausea or vomiting, and seeing halos or colored rings around light sources.
  • It can be treated through medications and surgery.
• Dry eyes:
  • The tear glands secrete lesser tears as one ages.
  • Tear production helps keep the eyes clean and comfortable and aids in proper vision. With reduced tear formation, the eyes feel gritty and tired.
  • Reduced tear production may increase the risk of eye inflammation and infections.
  • The doctor may prescribe lubricating eye drops or artificial tears to help with this problem.
• Floaters:
  • They refer to tiny moving specks or spots in the field of vision, particularly seen in bright light.
  • Occasional floaters are normal, but increased floaters along with flashes of light may indicate a serious underlying condition such as retinal detachment. 
  • Contact your doctor immediately if you see too many floaters suddenly along with flashes of light.
• Age-related macular degeneration (ARMD):
  • Results due to damage to a part of the retina called the macula.
  • It causes loss of central vision with preserved side or peripheral vision.
  • ARMD is the leading cause of vision loss in people who are 50 years and older.
  • Blurred central vision may cause difficulties recognizing faces or reading a clock.
  • Although there is no cure for this condition, treatment can reduce its progression and preserve your vision.

Other eye conditions that may occur with aging include:

• Reduced color contrast sensitivity
• Diabetic retinopathy
• Loss of peripheral vision
• Corneal degeneration
• Retinal detachment 
• Vitreous detachment
• Temporal arteritis
• Ptosis

Regular eye examinations are important to detect early vision changes. They help diagnose eye diseases early and prevent them from worsening through timely treatment. How often you need eye examination depends on your age and any health conditions you may have.

• Most healthy adults (18 to 64 years) need a comprehensive eye examination every two years.
• If they have certain underlying conditions such as diabetes, glaucoma, and a history of eye injury or surgery, they may need a comprehensive eye exam at least every year or more often if recommended by their doctor.
• People who are 65 years and older must get their eye exam done annually and more often if recommended by their doctor.
• People with high myopia (more than −4 D power) should get six-monthly eye checkups to prevent complications.

Not all vision changes are a normal part of aging. A healthy lifestyle coupled with regular eye checkups can help you keep your eyes healthy even as you age.

Tips to maintain a healthy vision include:

• Quit smoking
• Eat a healthy diet rich in whole grains, fruits, vegetables, nuts, and seeds
• Maintain normal blood pressure and cholesterol levels
• Exercise regularly
• Maintain a healthy weight
• Keep your blood sugar under check
• Avoid fatty, processed, salty, and sugary foods
• Protect your eyes from ultraviolet rays by wearing good quality sunglasses while outdoors
• Wear protective eyewear, especially while doing jobs such as welding or those that involve risk of eye injuries
• Go for regular eye checkups
• Use contact lenses only as directed and replace them regularly