Answering Common Questions about Eyesight and Eye Health

Our eyes allow us to see the world around us. But many people have questions about how vision works, potential eye problems, and ways to protect eye health. Below I address some frequently asked questions about eyesight and ocular wellness.

How Does LASIK Eye Surgery Work?

LASIK (laser-assisted in situ keratomileusis) uses a laser to reshape the cornea and improve vision. Here’s how it works:

• The surgeon creates a thin flap in the cornea using a microkeratome blade or femtosecond laser. This flap is folded back to expose the inner cornea.
• The exposed corneal tissue is then reshaped with an excimer laser. The laser removes microscopic amounts of tissue to correct nearsightedness, farsightedness, or astigmatism.
• After the cornea is reshaped, the flap is laid back into position. The surgery takes 10-20 minutes per eye.
• As light enters the newly shaped cornea, it focuses more directly on the retina for improved vision. The surface corneal flap heals within several days.

What Do Eyeballs Feel Like to Touch?

The outer surface of the eyeball has a similar squishy, grape-like consistency. The white sclera covering the eyeball is thick and protective but can deform slightly when touched. However, you should never apply pressure or poke the eye, as this can damage delicate interior structures.

How Can You Tell If Babies Need Glasses?

Signs an infant may need corrective lenses include:

• Eyes frequently crossing or drifting outwards
• Frequent eye rubbing
• Tilting head to one side
• Poor ability to track and focus on objects

If an eye exam reveals refractive errors like nearsightedness, farsightedness, or astigmatism, the ophthalmologist can prescribe infant glasses or contact lenses to aid visual development.

What Is the Purpose of Eyelashes?

Eyelashes serve as protective barriers to keep particles and debris from entering and irritating the eye. The lashes help block dust, dirt, pollen, and other particulate matter from contacting the sensitive cornea and conjunctiva. Proper eyelash length filters irritants while avoiding obstruction of sight.

Why Might One Eye Twitch Frequently?

• Stress, anxiety, or fatigue — Common triggers of eye twitching (myokymia).
• Caffeine or alcohol — Can exacerbate involuntary eyelid spasms.
• Nutrient imbalance — Magnesium or vitamin deficiency may contribute.
• Staring — Eye strain from prolonged computer use can cause twitching.
• Dry eyes — Insufficient lubricating tears may cause twitching and irritation.

If persistent, an eye twitch could also signal a neurological issue like blepharospasm. Consult an ophthalmologist if the twitching becomes bothersome.

Is It Dangerous to Sleep in Contact Lenses?

Sleeping in contacts significantly raises the risk of:

• Microbial keratitis — Bacterial infection of the cornea, which can damage vision. Contacts limit oxygen flow to the cornea while you sleep. Low oxygen boosts bacteria growth.
• Corneal ulcers — Open sores on the cornea from infection or abrasion.
• Corneal neovascularization — Harmful blood vessel growth into the cornea.

To avoid risks, remove contact lenses before sleeping and disinfect as directed. Use daily disposables if possible. Skip contacts if eyes become irritated and seek medical care promptly for symptoms.

Why Does Eyesight Worsen with Age?

The most common age-related cause of vision deterioration is cataracts. A cataract is clouding of the lens inside the eye that develops slowly over decades. As the normally clear lens turns yellowish and opaque, cataracts diffract light and cause blurry vision.

Other factors like the cornea flattening and pupil shrinking also reduce the eye’s focusing power. But cataracts account for most age-related vision loss. Modern cataract surgery can safely and effectively restore vision by replacing the cloudy lens with an artificial implant.

What Does 20/20 Vision Mean?

20/20 vision indicates normal visual acuity — the ability to see clearly at a standardized distance:

• The first number refers to testing distance in feet. So the standard is based on viewing a chart 20 feet away.
• The second number indicates the distance at which a person with “normal” acuity could read the same line you can read at 20 feet.
• So 20/20 means you can read at 20 feet a line that a person with typical vision could read from 20 feet away.
• 20/40 means you must stand 20 feet from a chart to read what normal vision can read at 40 feet — indicating impairment.

So 20/20 is considered normal vision. Better than 20/20 (like 20/15) is above average acuity. Worse than 20/20 indicates visual defects needing correction.

What Causes Eye Floaters?

Eye floaters occur when clumps of protein fibers coagulate in the vitreous, the gel-like fluid filling the eyeball. These stringy floaters cast tiny shadows on the retina as light passes through the vitreous. The shadows appear as spots drifting across the field of vision.

As we age, the vitreous liquefies, allowing more debris to coalesce into bothersome floaters. While usually harmless, persistently worsening floaters can indicate a more serious retinal tear or detachment requiring prompt medical care.

Are Carrots Really Good for Your Eyesight?

Carrots contain antioxidants like beta-carotene that convert to vitamin A, which helps maintain healthy eyes:

• Vitamin A fuels the eye’s photoreceptor cells, which detect light and enable vision.
• It also helps preserve and repair the cornea.
• Vitamin A deficiency can cause dry eye, night blindness, and corneal ulcerations.

So yes, the vitamin A precursors in carrots help nourish eyes and vision. Other dietary sources like milk, eggs, mangoes, and squash also provide essential vitamin A for ocular health. A nutrient-rich diet promotes healthy cells throughout the body, including in the eyes.

What Does “Legally Blind” Mean?

In the United States, legal blindness generally refers to:

• Best corrected visual acuity of 20/200 or less in the better seeing eye.
• Visual field diameter of 20 degrees or less in the better eye.

At 20/200 vision, the smallest letters you can read at 20 feet could only be identified by someone with typical vision when they are 200 feet away.

But “legal blindness” doesn’t indicate complete blindness. Someone legally blind may have partial vision allowing everyday function under certain conditions. Only about 10% of legally blind individuals have no vision at all.

Why Might Eyes Burn and Water When Cutting Onions?

Onions release compounds called lachrymatory factors when cut. These sulfur-containing gases interact with enzymes in ocular tissues to produce irritants like sulfuric acid that trigger a burning, stinging sensation. In response, the eyes release tears to flush out the irritant.

Strategies to minimize onion irritation:

• Chill onion before cutting to slow gas release
• Use a very sharp knife to limit cell damage
• Cut under running water to quickly wash away chemicals
• Position cutting board far from face
• Limit direct exposure to onion fumes

Do Eye Doctors Really Need to Dilate Your Pupils for Exams?

Dilating the pupils with eye drops serves several important purposes during eye exams:

• The widened pupil allows the doctor to fully visualize the retina and optic nerve in the back of the eye.
• Finding signs of conditions like glaucoma or macular degeneration requires a fully dilated pupil.
• The peripheral retina can’t be properly examined unless the pupils are wide.
• Eye drops paralyze the iris so eye focus and alignment can be accurately measured.

The side effects of temporary light sensitivity and blurred vision are minor inconveniences compared to the crucial diagnostic information gained from dilation. Following exams, effects diminish within several hours.

Can Excessive Screen Use Damage Eyesight?

Extensive screen time does not directly worsen vision or cause permanent eye damage. But digital eye strain can develop from prolonged computer, phone, or tablet use:

• Dry, irritated eyes from reduced blinking while staring at a screen.
• Eyestrain from fixed focus on digital text and images.
• Headaches, fatigue, and discomfort from repetitive screen work.

Practicing good screen hygiene limits these issues:

• Follow 20/20/20 rule — Every 20 minutes, look away 20 feet for 20 seconds.
• Adjust monitor height, distance, brightness, text size.
• Limit overhead lighting glare.
• Use artificial tear drops to lubricate dry eyes.
• Get comprehensive eye exams to update your glasses or contact lens prescription.

While excessive screen time won’t permanently degrade eyesight, it can contribute to discomfort and disruption in day-to-day visual function. Maintaining sound ergonomic habits preserves productivity and comfort when using digital devices for long durations. But don’t worry — your vision itself remains unaffected over the long run.

Do Blue Light-Blocking Computer Glasses Really Work?

Special eyewear marketed to block or filter blue light emitted from digital screens remains controversial:

• Blue light wavelengths can contribute to digital eye strain tied to overuse and poor ergonomics. Filtering provides mild relief for some users.
• But blue light does not damage eyes at typical digital exposure levels. Eye tissues filter most high-energy blue light.
• Many factors beside blue light cause digital eye strain — poor lighting, glare, dry air, small text, etc. Addressing these provides more substantial benefits for most people.

While a blue light filter can be one component of an overall eye-friendly workstation, the hype outpaces proven benefits. Following basic screen hygiene like the 20/20/20 rule reduces eyestrain far more than costly coated lenses. Target root ergonomic problems rather than fixating on blue light as the culprit.

Can Vision Therapy Strengthen Eyesight?

No evidence demonstrates vision therapy improves visual acuity itself. But it may help correct eye alignment/coordination issues like:

• Strabismus – crossed or misaligned eyes
• Amblyopia – lazy eye with weaker vision
• Ocular motor dysfunction – trouble focusing eyes in team

Via exercises and activities, vision therapy aims to train the visual system to properly track, team, and focus both eyes simultaneously. This facilitates binocular vision critical for depth perception.

But vision therapy cannot restore eyesight already lost to refractive error, eye disease, or old age. Nor does evidence support claims it can permanently correct refractive errors like nearsightedness or enhance focus. Traditional lenses, medication, or surgery as needed remains the proven approach to strengthen eyesight.

Can Night Mode and Dark Themes Save Your Vision?

Apps and devices now enable lowering the blue light emitted from screens via “night modes” and dark themes. But claims these settings preserve vision or sleep are exaggerated. Most rigorous research finds:

• Little high-quality evidence confirms blue light harms eyesight or sleep at typical consumer levels.
• While some people report less eyestrain using them, individual variability is high.
• Dark modes reduce harmful glare in very dim environments but provide no advantage in normal lighting.

If you simply prefer the aesthetic and comfort of darkened interfaces, utilize night modes to your enjoyment. But don’t expect significant vision or sleep benefits without proper lighting conditions and ergonomics. Following healthy overall habits outweighs any marginal improvements from these digital display settings alone.

Why Does Rubbing Eyes Cause Flashing Lights and Colors?

Rubbing eyes mechanically irritates retinal cells, causing random firing of color and light signals the brain then perceives as flashes and shapes called phosphenes. Here’s a deeper look:

• Rubbing compresses photosensitive rods and cones on the retina, scrambling their signals.
• This excites retinal ganglion cells, which carry visual information to the brain.
• The activated neurons fire randomly, generating ephemeral flashes known as phosphenes.
• Different cells produce different colors, creating fleeting kaleidoscopic patterns.

So rubbing essentially “presses” the vision areas of the brain, which respond with strange colors and shapes. While harmless, excessive eye rubbing can injure delicate surface tissues. So best not make a frequent habit of generating these odd ocular phenomena.

Do Contacts Really Need to Be Removed Every Night?

Sleeping in contacts substantially increases the risks of:

• Microbial keratitis — Potentially vision-threatening corneal infection. Lenses cut off oxygen flow needed to deter bacteria.
• Corneal neovascularization — Harmful blood vessel growth reducing corneal clarity.
• Corneal ulcer — Lenses can abrade the cornea. Open sores enable infection.
• Eye inflammation — Allergens and irritants get trapped under contacts.

Daily removal provides essential corneal rest. Disinfecting contacts eliminates microbes that accumulate. While skipping a day very rarely causes issues, accumulating risks make nightly removal strongly advised.

What Are Common Signs of Needing Vision Correction?

Symptoms indicating refractive visual errors like nearsightedness, farsightedness, or astigmatism include:

• Blurry distance/near vision
• Difficulty reading small print
• Eye strain or fatigue
• Headaches after sustained focus
• Squinting or tilting head to see better
• Trouble seeing screens or chalkboards

Even if you have “perfect” 20/20 vision, a comprehensive eye exam can uncover subtle focusing issues or early stages of presbyopia as we age. An accurate prescription keeps vision optimized throughout life.

Can Retinal Detachment Be Prevented?

While you can’t prevent retinal detachment completely, these practices promote retinal health and prompt treatment:

• Get regular dilated eye exams to detect warning signs like retinal tears. Early treatment prevents detachment.
• Visit an ophthalmologist immediately if you notice new flashes, floaters, shadows, or vision loss.
• Avoid ocular trauma — wear eye protection when playing sports or doing activities with eye risks.
• Control existing conditions like myopia, diabetes, or high blood pressure known to increase detachment risks.
• Follow all post-op directions carefully after any eye surgery. Certain procedures like cataract surgery increase detachment risk.

Retinal detachment seldom arises from inherent eye weaknesses. But identifying and managing known risk factors reduces odds of this serious complication.

Do Eye Exercises Really Improve Vision?

No evidence demonstrates eye exercises can correct refractive errors or eliminate presbyopia. But eye exercises offer other real benefits:

Athletic performance – Sports vision training improves visual skills like tracking, reaction time, and hand-eye coordination useful for athletes.

Eye coordination – Orthoptic exercises may help eye alignment and teaming, relieving amblyopia or strabismus.

Eye comfort – Brief breaks doing alternating lateral eye movements relieve fixation fatigue.

But claims of exercises permanently correcting nearsightedness or reading vision issues are unfounded. Don’t expect eye calisthenics to replace traditional means of improving visual acuity like glasses, contact lenses, refractive surgery, or cataract treatment when truly needed.

By incorporating the habits above and getting regular comprehensive eye exams, you can keep your eyes healthy and maximize your eyesight potential throughout life. Protecting your vision starts with learning how your eyes function and how to prevent problems before they occur.