This year was my 20th anniversary since I got my LASIK at The Eye Center! I’ve been coming every year since for a checkup. The office staff and docs are friendly, the office is clean.
— Jenn Whitaker
Corneal Thickness Testing and Glaucoma Risk
What to Expect During Your Pachymetry Test
Pachymetry is a brief, comfortable test that fits easily into your regular eye exam. Knowing what to expect helps you feel prepared and relaxed before your visit.
We use a specialized instrument called a pachymeter to take the measurement. The most common method uses ultrasound waves that bounce off the front and back surfaces of your cornea to calculate its thickness. An optical version also exists that uses light instead and requires no contact with your eye at all.
Results are reported in microns, which are very small units of measurement. We typically take several readings of each eye to ensure our results are consistent and reliable.
You do not need to fast or change your routine before a pachymetry test. Continue taking any prescribed medications as directed. If you wear contact lenses, we may ask you to remove them before the test, and the timing will depend on your lens type and why we are performing the test.
- Soft contact lenses may need to be removed on the day of the exam
- Rigid gas permeable lenses can reshape the cornea temporarily and may need to be left out for a longer period
- We will give you specific guidance based on your situation
Before the ultrasound method, we place numbing drops in your eyes so you will not feel discomfort. You may notice a very mild sense of pressure when the probe briefly touches your cornea, but this should not cause any pain. With the optical method, you simply look into the instrument while it takes measurements without touching your eye at all.
The numbing drops wear off within about 20 to 30 minutes after the test. Most patients describe the experience as quick and easy. While the numbing is in effect, avoid rubbing your eyes to protect the surface from accidental irritation.
There is very little recovery involved after pachymetry. Mild tearing or brief blurry vision from the numbing drops is normal and passes quickly.
- Do not rub your eyes until the numbing effect has fully worn off
- Ask us when it is safe to reinsert contact lenses if you wear them
- Contact our office if you notice persistent pain, increasing redness, discharge, or significant light sensitivity after the test
Understanding Your Pachymetry Results
Your pachymetry number is meaningful only when we look at it alongside your other test results. The goal is not to match a single ideal measurement but to understand what your specific thickness means for your individual eye health.
Average corneal thickness falls around the mid-500s in microns, but many healthy eyes fall above or below that range. Because measurements also vary slightly depending on the instrument and technique used, we focus on how your result compares to the context of your pressure readings, optic nerve health, and overall risk factors rather than matching any fixed number.
If your cornea is thinner than average, there is a reasonable chance that your measured eye pressure is lower than your true pressure. This means your actual glaucoma risk may be higher than the pressure number alone suggests. We respond to this by paying closer attention to your optic nerve and visual field results.
- Your target pressure for treatment may be set lower than it would be for someone with average thickness
- We may recommend more frequent monitoring visits
- Earlier treatment may be considered if other risk factors are also present
If your cornea is thicker than average, your measured pressure reading may be higher than your true pressure. This can sometimes make glaucoma appear more likely than it actually is. In patients with elevated pressure readings but no signs of optic nerve damage, thicker corneas are associated with a lower risk of developing glaucoma over time.
That said, thick corneas do not rule out glaucoma. We still carefully examine your optic nerve and perform visual field testing before drawing any conclusions about your risk or treatment needs.
Your pachymetry result is one component of a broader evaluation that includes your age, family history, ethnic background, optic nerve appearance, and visual field test findings. We also consider whether you use or have previously used steroid eye drops, steroid injections near the eye, or oral steroids, since steroids can raise eye pressure in some people and that history matters for understanding your readings.
- Corneal thickness helps us weigh all other factors together
- No single measurement determines your care plan on its own
- Your personal and family history significantly influence how we interpret results
- The full combination of findings guides our treatment recommendations
Standard eye pressure measurements assume that everyone has average corneal thickness. When your cornea differs from that assumed average, the reading will be shifted in one direction or the other. There is no single conversion formula that gives us a precise corrected number because corneal stiffness, elasticity, and measurement technique all contribute. This is exactly why the separate pachymetry test is so valuable for putting your pressure readings in proper context.
Who Needs Corneal Thickness Testing
Pachymetry is not limited to patients already diagnosed with glaucoma. Several groups benefit from knowing their corneal thickness as part of a thorough eye health evaluation.
If your eye pressure readings are above normal but you show no signs of glaucoma damage yet, this situation is called ocular hypertension (high eye pressure without visible damage). Pachymetry helps us determine whether your pressure is genuinely elevated or whether a thick cornea is making it read higher than it truly is. This distinction guides whether we recommend treatment, closer monitoring, or a standard follow-up schedule.
Having a close relative with glaucoma raises your personal risk significantly. In these cases, pachymetry establishes a useful baseline that allows us to monitor your eyes more effectively over time and detect any early changes before they affect your vision.
- Baseline measurements help us track any shifts over the years
- Your thickness helps us tailor how frequently we check in with you
- Combined with other screening tools, it gives us a clearer picture of your individual risk
For those already living with glaucoma, pachymetry helps us set the right target eye pressure for your treatment. The goal of glaucoma therapy is to lower pressure enough to protect your optic nerve from further damage. Your corneal thickness directly influences where that target should be and whether your current treatment is effective.
Before laser vision correction, we must confirm that your cornea is thick enough to safely undergo the procedure. LASIK reshapes the cornea by removing a small amount of tissue, which permanently reduces corneal thickness. If your cornea is too thin to begin with, the procedure may not be appropriate, and we will discuss alternative options with you.
- Adequate pre-surgical thickness is a safety requirement for LASIK
- We ensure enough tissue will remain after the procedure
- Patients with borderline or thin corneas may be better candidates for alternative treatments
How Your Results Shape Your Glaucoma Care Plan
Pachymetry findings directly influence how we monitor and treat you. Combined with our computerized glaucoma testing, your results help us build a personalized strategy for protecting your vision over the long term.
Patients with thin corneas and borderline pressure readings often benefit from more frequent eye exams than the standard once-a-year schedule. More regular visits allow us to detect early signs of glaucoma damage before significant vision loss occurs. In contrast, patients with thick corneas and otherwise healthy findings may be comfortable with annual monitoring even if pressure readings are slightly elevated.
When treatment is necessary, we establish a target eye pressure based on what is individually safe for your eyes. Corneal thickness is one of the factors that shapes this target.
- Thin corneas often call for a lower target pressure to account for underestimated true pressure
- Thick corneas may allow a slightly higher acceptable pressure in low-risk patients
- Targets are updated over time based on how your optic nerve and visual field respond to treatment
Pachymetry is most powerful when combined with visual field testing, optic nerve imaging, and gonioscopy. Visual field testing checks for blind spots in your side vision. Optic nerve imaging using optical coherence tomography (OCT) measures the thickness of the nerve fiber layer to detect structural damage before vision is noticeably affected. Gonioscopy is an exam of the drainage angle inside your eye that shows how fluid flows out.
Together, these tools give us a complete view of your glaucoma status so that no important detail is missed.
Treatment decisions are never based on corneal thickness alone. We consider the full picture, including your pressure trends over time, optic nerve appearance, visual field findings, and personal risk factors. If your corneal thickness suggests your measured pressure is underestimating your true pressure, and particularly if there is any sign of optic nerve damage or visual field loss, we are more likely to recommend starting treatment sooner.
- Evidence of optic nerve damage or visual field loss is a key signal to begin treatment
- Thin corneas combined with other risk factors often support earlier intervention
- Preserving your existing vision is always the priority
Managing Glaucoma Risk Over Time
Once we understand your corneal thickness and full glaucoma risk profile, we create a care plan that may include medication, in-office procedures, and lifestyle guidance. Consistent follow-through on your part makes a meaningful difference in outcomes.
When treatment is needed, prescription eye drops are typically the first approach. Different types of drops work in different ways to reduce fluid pressure inside the eye. Common categories include prostaglandin analogs, beta blockers, and carbonic anhydrase inhibitors, each with their own dosing schedule and potential side effects.
Using your drops exactly as prescribed is essential. Some patients experience mild side effects such as redness, stinging, or eyelash changes with prostaglandin medications, or effects on heart rate or breathing with beta blockers. We tailor our medication choices to your overall health and adjust them at your follow-up visits based on how your pressure and optic nerve are responding.
If eye drops are not sufficient to reach your target pressure, or if using drops consistently is a challenge, we may recommend a laser procedure. Selective laser trabeculoplasty (SLT) helps fluid drain out of the eye more easily and is performed in-office with numbing drops. The procedure typically takes only a few minutes and has a favorable safety profile.
- SLT can reduce pressure without relying solely on daily eye drops
- Effects may last several years but can diminish over time
- The treatment can often be repeated if needed
For cases where medications and laser treatment cannot adequately control eye pressure, surgical options may be considered. Procedures such as trabeculectomy create a new drainage channel, while drainage implant devices help fluid exit the eye through a small tube. Minimally invasive glaucoma surgery (MIGS) options may also be discussed during your consultation with our surgeon. Surgery is typically reserved for more advanced cases or when other treatments have not reached your target pressure.
We discuss the full range of benefits and risks with you before any surgical recommendation. Recovery generally takes several weeks, with frequent follow-up visits during healing.
Your habits between appointments matter just as much as the care you receive in our office. Consistency with your prescribed eye drops, protective eyewear during high-risk activities, regular exercise, a balanced diet, and not smoking all support better long-term eye health.
- Use prescribed drops at the same time each day for best results
- Store medications properly and note expiration dates
- Keep all scheduled follow-up appointments even when you feel completely fine
- Report any new changes in your vision promptly
Most forms of chronic glaucoma progress slowly without noticeable symptoms, which is why regular monitoring is so important. However, acute angle closure glaucoma is a medical emergency that causes sudden symptoms including severe eye pain, headache, nausea, vomiting, blurred vision, and colored halos around lights. This condition can cause permanent vision loss within hours if not treated right away.
If you experience any of these sudden symptoms, contact our office immediately or go to an emergency room if we are unavailable.
Frequently Asked Questions
Here are answers to questions our patients often have about corneal thickness and how it relates to glaucoma care.
For most patients, corneal thickness is measured once during an initial glaucoma evaluation and does not need to be repeated regularly because it stays stable in healthy eyes. We may repeat the test if you are being considered for surgery, if significant time has passed since your last measurement, or if a corneal condition has been identified that might affect the reading. This is different from other glaucoma tests like visual fields and optic nerve imaging, which we monitor on a regular schedule.
Yes, and this is an important detail to share with us. LASIK permanently thins the cornea, which affects both how pressure is measured and how we interpret that measurement. In post-LASIK eyes, standard pressure readings may underestimate true eye pressure more than they would in an unoperated eye. Knowing your surgical history allows us to factor this in and use additional testing methods when needed to get the most accurate assessment of your risk.
Pachymetry is most useful when there is a specific reason to question whether your measured pressure reflects your true pressure. If your readings are solidly normal and you have no other risk factors, we may not need to perform pachymetry routinely. However, if you have a family history of glaucoma, a thin cornea is suspected, or your pressure is at the upper end of normal, the test provides valuable context. Your eye doctor will recommend it when it adds meaningful information to your evaluation.
Corneal thickness itself does not change with glaucoma progression in most cases, so it is not a marker we track over time to assess disease activity. The tools we use to monitor progression include visual field tests, which detect changes in your side vision, and optic nerve imaging with OCT, which measures the nerve fiber layer. Pachymetry gives us a baseline for interpreting pressure, while these other tests tell us whether the disease is advancing.
No. Beyond glaucoma risk assessment, corneal thickness is a critical measurement before LASIK and other refractive surgeries to confirm there is adequate tissue for a safe procedure. It is also used to evaluate corneal diseases such as keratoconus and Fuchs dystrophy, where changes in thickness signal disease progression. In some cases, thickness measurements help us assess healing after corneal injury or infection. If any of these situations apply to you, we will discuss the specific implications for your care.
Skipping exams is not recommended regardless of corneal thickness. While thicker corneas are associated with lower glaucoma risk in certain research populations, they do not eliminate the possibility of developing glaucoma or other eye conditions. Many serious eye conditions, including early glaucoma, retinal disease, and other pressure-related changes, develop without any symptoms you would notice on your own. Regular comprehensive eye exams remain the only reliable way to detect these problems before they affect your vision.
Schedule Your Glaucoma Evaluation at The Eye Center
If you have concerns about glaucoma, elevated eye pressure, or a family history of vision loss, our team is here to help with a thorough, personalized evaluation. At The Eye Center, we combine corneal thickness testing with our computerized glaucoma testing to give you the most complete picture of your eye health. We are proud to serve patients throughout Northern Virginia and look forward to helping you protect your vision for years to come.