Glaucoma is the second leading cause of blindness worldwide, and the leading cause of irreversible blindness. It affects an estimated 3 million Americans, with roughly half undiagnosed. It is a disease that can rob peripheral vision silently and progressively — often before the affected person notices anything is wrong — which is why it is sometimes called the “silent thief of sight.”
For anyone considering elective vision correction surgery, glaucoma — whether diagnosed, suspected, or only a risk factor in the family history — introduces specific considerations that should be part of any comprehensive pre-surgical evaluation. This guide, part of the Eye Health and Vision Care resource, covers what glaucoma is, how it is detected and monitored, and how it intersects with laser and other vision correction procedures.
What Is Glaucoma?
Glaucoma is not a single disease but a family of conditions characterized by progressive damage to the optic nerve — the neural cable that transmits visual information from the retina to the brain. As optic nerve fibers are lost, corresponding areas of the visual field (the full panorama of what the eye can see) are affected.
The most common form is primary open-angle glaucoma (POAG), in which the aqueous humor (the fluid inside the anterior chamber of the eye) drains too slowly through the trabecular meshwork, causing gradual buildup of intraocular pressure (IOP). This elevated pressure, over time, damages the optic nerve.
However, normal-tension glaucoma — in which IOP is within the statistically normal range (below 21 mmHg) but the optic nerve is still damaged — accounts for approximately one-third of glaucoma cases in the United States and a higher proportion in East Asian populations. This is an important point: normal IOP does not rule out glaucoma.
Primary angle-closure glaucoma, though less common in Western populations, involves a physically narrowed angle between the iris and cornea that blocks aqueous outflow. It can present as a sudden, acute attack with severe eye pain, nausea, and rapid vision loss — a medical emergency.
Risk Factors for Glaucoma
Understanding risk factors is the first step in appropriate screening. Key risk factors include:
Age: Risk increases significantly after 60. After 80, approximately 10% of Americans have glaucoma.
Elevated IOP: The most significant modifiable risk factor. IOP above 21 mmHg significantly increases risk. However, as noted, normal IOP does not exclude the diagnosis.
Family history: First-degree relatives of glaucoma patients have a four-to-nine-fold elevated risk.
Race/ethnicity: Primary open-angle glaucoma is three to four times more prevalent in African Americans than in European Americans, tends to onset earlier, and progresses faster.
High myopia: Highly myopic eyes have structural features that increase optic nerve vulnerability to pressure damage. Additionally, the elongated sclera in high myopes creates a different biomechanical environment at the optic nerve head.
Thin central cornea: Thinner corneas cause tonometry to underestimate true IOP, masking glaucoma risk. Thin corneas may also be an independent risk factor for optic nerve susceptibility.
Diagnosing Glaucoma: What a Complete Evaluation Includes
Diagnosis of glaucoma requires more than a single IOP measurement. A comprehensive glaucoma evaluation includes:
Tonometry: Measurement of IOP. Goldmann applanation tonometry (GAT) is the gold standard. Multiple measurements over different times of day (diurnal curve) are often informative.
Pachymetry: Measurement of central corneal thickness, which adjusts the interpretation of IOP measurements. Thin corneas cause GAT to underread true IOP; thick corneas cause overreading.
Ophthalmoscopy or optic nerve imaging: Direct assessment of the optic nerve head, including the cup-to-disc ratio, rim tissue health, and presence of hemorrhages. Optic nerve photography and OCT (optical coherence tomography) of the retinal nerve fiber layer (RNFL) allow objective, quantitative longitudinal tracking.
Visual field testing: Automated perimetry (e.g., Humphrey Visual Field Analyzer) documents functional vision loss. Because glaucoma begins peripherally, patients often cannot perceive early field loss without testing.
Gonioscopy: Examination of the anterior chamber angle to determine whether it is open or narrow/closed — critical for subtype classification and treatment planning.
Glaucoma and LASIK: Specific Interactions
Glaucoma and elective refractive surgery intersect at multiple points.
IOP measurement accuracy post-LASIK: LASIK reduces central corneal thickness by removing stromal tissue. Since IOP is measured at the corneal surface, a thinner post-LASIK cornea will cause Goldmann applanation tonometry to underestimate true IOP — potentially masking glaucoma development or progression in LASIK patients who are later screened. This is a genuine and well-documented concern.
Post-LASIK patients being screened for glaucoma need IOP measurements that account for the altered corneal geometry. Dynamic contour tonometry (DCT) or the Corvis ST (which measures corneal biomechanics during tonometry) are less affected by corneal thickness changes than Goldmann applanation.
Glaucoma diagnosis prior to LASIK: The presence of glaucoma does not automatically disqualify a patient from LASIK. However, several considerations apply:
- The surgical evaluation should include pachymetry-adjusted IOP, dilated optic nerve assessment, and ideally an automated visual field test
- Patients with elevated IOP should have their IOP stabilized before surgery
- Patients taking topical glaucoma drops (prostaglandin analogs, beta-blockers, etc.) may have a compromised ocular surface from preservatives, which affects both dry eye status and surgical healing
Angle-closure risk: LASIK flap creation increases IOP temporarily. In patients with narrow angles, this transient IOP spike during flap creation could theoretically precipitate an angle-closure event. Gonioscopy should be performed to assess angle anatomy in any patient with risk factors for angle closure.
EVO ICL and glaucoma: The EVO ICL (implantable collamer lens) also has implications for glaucoma management. ICL insertion reduces the anterior chamber depth slightly, which can narrow the angle. In patients with narrow angles or elevated risk for angle closure, careful pre-operative angle assessment is mandatory. The current generation of EVO ICL with its central port (KS-AquaPORT) has substantially reduced the risk of IOP elevation that was associated with older ICL designs. See EVO ICL Awards for recognized surgeons with lens implant expertise.
Glaucoma Treatment and Vision Correction Surgery Sequencing
For patients on glaucoma treatment who are considering vision correction surgery, sequence matters.
If glaucoma is well-controlled with topical medication alone, and the patient meets all other candidacy criteria, vision correction surgery can often proceed — with appropriate adjustments to IOP monitoring post-operatively. Topical glaucoma drops are continued as prescribed.
If the patient has had a filtering surgery (trabeculectomy) or tube shunt for glaucoma, the surgical planning for refractive correction becomes considerably more complex. These procedures create outflow pathways that can interact with the pressure changes of LASIK or ICL surgery. Refractive procedures after filtering surgery require subspecialty coordination.
Patients who have had corneal refractive surgery and later develop glaucoma should inform their glaucoma specialist of their surgical history, as it directly affects IOP interpretation and possibly optic nerve assessment.
Monitoring: The Foundation of Glaucoma Management
Whether a patient has established glaucoma or simply glaucoma risk factors, ongoing monitoring is the cornerstone of management. A patient with a strong family history of glaucoma, elevated IOP, or optic nerve findings consistent with early disease should be seen at minimum annually for comprehensive glaucoma assessment — more frequently (every four to six months) if on treatment or with moderate-to-advanced disease.
The annual eye exam in a glaucoma-at-risk patient should always include IOP measurement, dilated optic nerve evaluation, and RNFL OCT imaging. Visual field testing is added when clinically indicated.
Related Pages
- Eye Health and Vision Care — Complete hub overview
- Corneal Health and Vision Correction — Corneal thickness and IOP measurement
- Cataracts and Vision Correction — Concurrent age-related conditions
- Annual Eye Exams: Why Regular Checkups Matter — Glaucoma screening protocols
Frequently asked questions:
- When Should I See an Eye Doctor Immediately?
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*All content is for educational purposes. Consult a qualified ophthalmologist for glaucoma evaluation and surgical candidacy assessment.*