Disclaimer: This article is for informational purposes only and does not constitute medical advice. LASIK candidacy must be determined through a comprehensive eye examination by a qualified ophthalmologist or refractive surgeon. The information presented is based on FDA guidelines, peer-reviewed medical research, and clinical practice standards.
So you’re thinking about LASIK. Maybe you’re tired of fumbling for your glasses first thing in the morning, or fed up with dry, irritated eyes from contacts. You’ve heard the success stories of friends who can finally see the alarm clock without reaching for their nightstand, coworkers who ditched their glasses for good.
But then the questions start rolling in: Am I even eligible? Is my prescription too high? Are my eyes healthy enough? What if I have that other condition my doctor mentioned?
Here’s the truth: LASIK has helped millions of people see clearly, but it’s not right for everyone. And that’s actually a good thing because the last thing you want is a surgeon who’ll operate on anyone who walks through the door.
Let’s walk through everything that determines LASIK candidacy, so you’ll know exactly what to expect when you schedule that consultation.
The Basic Requirements: Where Everyone Starts
Before we dive into the nuances, let’s cover the fundamentals. These are the baseline criteria that most LASIK surgeons look for:
1. You Need to Be at Least 18 Years Old
The FDA has approved LASIK for patients 18 and older, but here’s the thing: just because you can get LASIK at 18 doesn’t necessarily mean you should.
Why? Your eyes are still changing through your late teens and early twenties. Most eye care specialists agree that the optimal age for LASIK is around 25, when prescriptions are more likely to have stabilized. Studies show that 90-95% of prescriptions stabilize by the early 20s.
Think of it this way: if your prescription is still changing, correcting your vision today might mean you need glasses again in a few years. Most surgeons prefer to wait until your eyes have reached what’s called “ocular maturity.”
The sweet spot: Between ages 25 and 40, when prescriptions are stable and age-related vision changes (like presbyopia) haven’t kicked in yet.
2. Your Prescription Must Be Stable
This is huge. Your eyeglass or contact lens prescription should not have changed significantly in the past year, preferably two.
What counts as “stable”? Generally, no more than 0.5 diopters of change over 12 months. If your prescription is still fluctuating, LASIK is like aiming at a moving target; the results won’t be accurate.
Why does your prescription change? Lots of reasons:
- You’re still young, and your eyes are developing
- Hormonal changes (pregnancy, nursing)
- Uncontrolled diabetes affects blood sugar levels
- Certain medications
Bottom line: If you’ve been updating your prescription every year, you’re probably not ready for LASIK yet.
3. Your Prescription Must Fall Within Treatable Ranges
The FDA has approved LASIK for specific prescription ranges:
- Nearsightedness (myopia): Up to -12.00 diopters
- Farsightedness (hyperopia): Up to +6.00 diopters
- Astigmatism: Up to 6.00 diopters
Now, here’s the reality: most experienced surgeons set their limits lower than these FDA maximums. Why? Because higher prescriptions require removing more corneal tissue, which increases risks.
If your prescription is on the higher end, you might still be a candidate, but your surgeon will need to carefully evaluate your corneal thickness to ensure there’s enough tissue to work with safely.
The Corneal Thickness Factor: Why It Matters So Much
Here’s something most people don’t know until their consultation: your corneal thickness is one of the most critical factors in LASIK candidacy.
Understanding the Numbers
The average cornea is about 520-540 microns thick (a micron is one-thousandth of a millimetre). But normal can range from 470 to 630 microns.
During LASIK, the surgeon:
- Creates a corneal flap (usually 100-120 microns with modern femtosecond lasers)
- Removes tissue to correct your vision (about 12-15 microns per diopter of correction)
- Must leave enough tissue behind to maintain structural integrity
The critical minimum: Most surgeons require at least 250 microns of remaining tissue, though 300 microns is considered safer to avoid a serious complication called corneal ectasia, a weakening and bulging of the cornea.
Quick Math Example
Let’s say you have:
- Original corneal thickness: 520 microns
- Prescription: -6.00 diopters
- Flap thickness: 110 microns
- Tissue removal needed: 72-90 microns (12-15 microns × 6 diopters)
- Minimum remaining: 300 microns
Calculation: 520 – 110 – 90 – 300 = 20 microns of “buffer”
You’d likely be approved, but just barely. Someone with thinner corneas or a higher prescription might not qualify for LASIK but could still be a great candidate for PRK or SMILE, which preserves more tissue.
Eye Health Requirements: What Disqualifies You
Your eyes need to be healthy for LASIK to work safely. Here are the conditions that can affect candidacy:
Dry Eye Syndrome
Dry eyes are extremely common, and LASIK can temporarily worsen this condition.
If you have mild, manageable dry eyes, you might still qualify after treatment to stabilize your tear film. But severe, untreated dry eyes are usually a dealbreaker for LASIK. Your surgeon may recommend PRK or SMILE instead, which tend to cause less dry eye.
Signs you might have dry eyes:
- Burning, stinging, or gritty sensation
- Eye redness
- Difficulty wearing contacts for a full day
- Blurry vision that improves with blinking
Corneal Conditions
Conditions like keratoconus (progressive thinning and bulging of the cornea), corneal scars, or irregular corneas typically disqualify you from LASIK. These structural issues make it unsafe to remove additional tissue.
Previous Eye Surgery or Trauma
Previous eye surgeries or trauma in the treatment area need careful evaluation. Scar tissue or altered corneal structure could affect healing and results.
Large Pupils
If your pupils are naturally large, you could face increased risk of side effects like halos, glare, or poor night vision after LASIK. This doesn’t automatically disqualify you, but it requires special consideration.
Health Conditions That Affect Candidacy
LASIK isn’t just about your eyes; your overall health matters too.
Autoimmune Diseases
Conditions like rheumatoid arthritis, lupus, and gren’s syndrome can impair healing. The FDA and American Academy of Ophthalmology consider uncontrolled autoimmune or immune-mediated disease a contraindication to laser refractive surgery.
That said, if your autoimmune condition is mild and well-controlled, LASIK might still be possible. This requires careful evaluation of your specific situation.
Diabetes
The FDA considers diabetes a relative contraindication to LASIK, primarily due to concerns about delayed wound healing and increased infection risk.
But here’s where it gets interesting: having diabetes doesn’t automatically disqualify you. What matters is:
- Blood sugar control: Your hemoglobin A1c should be stable and well-controlled (typically below 7.5%) for at least 6 months
- No diabetic eye disease: Any history of diabetic retinopathy is typically a dealbreaker
- Stable prescription: Fluctuating blood sugar can cause prescription changes
- Overall health: No other diabetic complications
Several studies have shown that diabetic patients with excellent glucose control can achieve safe outcomes with LASIK, though healing may take slightly longer.
Pregnancy and Nursing
Hormonal changes during pregnancy and breastfeeding can cause temporary vision fluctuations and increased corneal swelling. Most surgeons recommend waiting until you’ve stopped nursing and your hormone levels have stabilized.
Medications That Affect Healing
Certain medications can interfere with healing:
- Isotretinoin (Accutane): Used for severe acne; you’ll need to be off it for several months
- Amiodarone (Cordarone): A heart medication
- Oral steroids: Can delay healing
- Immunosuppressants: Increase infection risk
Always be completely transparent about all medications during your consultation.
Lifestyle Considerations: Does Your Life Fit LASIK?
Your daily activities and profession can influence whether LASIK is your best option.
Contact Sports and High-Impact Activities
If you’re a boxer, MMA fighter, or wrestler, sports where blows to the face are common, PRK or SMILE might be better choices. The LASIK flap, while secure, could theoretically be displaced by significant trauma years later.
Military and Law Enforcement
Interestingly, many branches of the U.S. military now approve LASIK, but PRK remains the gold standard for active-duty personnel. The military specifically approves PRK for all branches because of its superior long-term structural stability.
Career Requirements
Some professions (like commercial pilots or certain military roles) have specific vision requirements. If LASIK could help you meet those requirements, great, but make sure you understand your career field’s specific policies before proceeding.
What to Expect at Your LASIK Evaluation
When you go in for a consultation, here’s what a thorough evaluation should include:
Comprehensive Testing
- Refraction test: Measures your exact prescription
- Corneal pachymetry: Ultrasound measurement of corneal thickness
- Corneal topography: Maps the surface of your cornea to detect irregularities
- Pupil dilation: Allows examination of your retina and overall eye health
- Wavefront analysis: Identifies higher-order aberrations beyond basic prescription
- Tear film evaluation: Assesses dry eye risk
Medical History Review
Your surgeon should ask about:
- Eye health history
- Medical conditions
- All medications (prescription and over-the-counter)
- Allergies
- Previous surgeries
- Lifestyle and visual demands
The Honest Conversation
A good surgeon will:
- Explain WHY you are or aren’t a candidate
- Discuss alternative options if LASIK isn’t right for you
- Set realistic expectations about outcomes
- Answer all your questions without rushing
Key questions to ask during your consultation:
- Based on my specific eye anatomy, which procedure do you recommend and why?
- What are MY specific risks?
- What’s your complication rate?
- What happens if I need an enhancement later?
- Am I at risk for any specific complications given my health history?
When LASIK Isn’t Right And That’s Okay
If you’re told you’re not a LASIK candidate, don’t despair. It doesn’t mean you’re stuck with glasses forever. Alternative options include:
- PRK: No flap required; great for thinner corneas
- SMILE: Minimally invasive; excellent for dry eye-prone patients
- ICL (Implantable Collamer Lens): For very high prescriptions
- Clear lens exchange: Sometimes appropriate for those over 50
The surgeon who tells you “no” when LASIK isn’t safe for you is doing you a huge favour. Your eye health and safety should always come first.
The Bottom Line: It’s All About YOU
LASIK candidacy isn’t about checking boxes on a generic list; it’s about your unique eye anatomy, your health history, your lifestyle, and your vision goals.
You might be a perfect candidate. You might be borderline. You might be better suited for a different procedure. And you won’t know for sure until you have that comprehensive evaluation.
What you CAN do right now:
- Make sure your prescription has been stable for at least a year
- Get your diabetes or other health conditions well-controlled
- Stop smoking (it impairs healing)
- Gather your medical history and medication list
- Schedule a consultation with an experienced refractive surgeon
The consultation is just that, a consultation. You’re not committing to surgery by walking in the door. You’re gathering information to make the best decision for your eyes and your life.
And if LASIK turns out to be right for you? You might just join the millions who say it’s one of the best decisions they ever made.
Ready to find out if you’re a candidate? Schedule a comprehensive LASIK evaluation with a qualified refractive surgeon. Come with questions, be honest about your health history, and get the answers you need to make an informed decision.
Your clearer future might be closer than you think.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. LASIK candidacy must be determined through a comprehensive eye examination by a qualified ophthalmologist or refractive surgeon. The information presented is based on FDA guidelines, peer-reviewed medical research, and clinical practice standards.
