A keratectomy is a surgical procedure that removes a portion of the cornea, the clear front surface of the eye. It’s most commonly performed to correct vision problems like nearsightedness, farsightedness, and astigmatism, but it can also treat corneal diseases, scars, and surface irregularities. The two most well-known types are photorefractive keratectomy (PRK) for vision correction and phototherapeutic keratectomy (PTK) for treating corneal conditions.
Types of Keratectomy
There are three basic categories. The first and most common uses an excimer laser to reshape or smooth the cornea. PRK and PTK both fall into this group. The second is a wedge-shaped keratectomy, where a small wedge of corneal tissue is removed to reduce astigmatism that developed after a corneal transplant or cataract surgery. The third is a lamellar crescentic keratectomy, a more specialized procedure used for specific degenerative corneal conditions like Terrien’s marginal degeneration.
For most people searching this term, the relevant procedure is either PRK or PTK.
PRK: Vision Correction Without a Flap
Photorefractive keratectomy uses an excimer laser to reshape the front surface of the cornea, changing how light bends as it enters the eye. It corrects nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. PRK typically treats myopia up to about -7.00 diopters and astigmatism up to -2.00 diopters, though the laser manufacturers list wider ranges.
The key difference between PRK and LASIK is what happens before the laser fires. In LASIK, a thin flap is cut into the cornea and folded back. In PRK, the outer layer of the cornea (the epithelium) is completely removed instead. This means PRK doesn’t require as much corneal thickness to be safe, making it a better option for people with thinner corneas (generally those with less than about 490 micrometers of central corneal thickness). It’s also preferred for people in contact sports or occupations where a flap could be dislodged by impact.
The tradeoff is a longer, less comfortable recovery. But the final visual results are comparable to LASIK.
PTK: Treating Corneal Disease
Phototherapeutic keratectomy uses the same excimer laser, but the goal is different. Instead of reshaping the cornea to fix a prescription, PTK removes damaged or diseased tissue from the corneal surface. It treats conditions like recurrent corneal erosions (where the outer layer of the cornea repeatedly breaks down), corneal dystrophies that cause cloudy deposits, corneal scars, and certain degenerative conditions.
PTK can improve vision and delay or avoid the need for a corneal transplant in cases where cloudy deposits continue to form over time. During the procedure, smoothing agents are sometimes applied to the corneal surface to help the laser remove tissue more evenly when the surface is irregular.
What Happens During the Procedure
Keratectomy is an outpatient procedure that takes only a few minutes per eye. For PRK, the first step is removing the corneal epithelium. This is done using one of three methods: a brief application of diluted alcohol to loosen the cells, a mechanical brush, or the laser itself. Studies comparing laser removal to manual scraping found no significant difference in final visual outcomes, corneal clarity, or healing time. There was a slight trend toward more precise correction with laser removal, but the difference wasn’t statistically meaningful.
Once the epithelium is cleared, the excimer laser reshapes the underlying corneal tissue. The entire laser treatment typically lasts less than a minute. Afterward, a soft bandage contact lens is placed over the eye to protect it while the epithelium regrows and to reduce discomfort during the first several days of healing.
Recovery Timeline
PRK recovery is noticeably slower than LASIK. The bandage contact lens stays on for about a week, and at that first follow-up visit, vision is often still blurry. One patient account from Cleveland Clinic described seeing 20/50 in one eye and 20/60 in the other at the one-week mark.
Unlike LASIK, where many people notice dramatically sharper vision within a day, PRK improvement tends to be gradual. Vision sharpens over weeks to months as the corneal surface heals and stabilizes. Most people notice meaningful improvement within the first few weeks, but full stabilization can take three months or longer. That same patient reported achieving 20/16 vision (slightly better than 20/20) at the three-month follow-up.
Discomfort in the first few days can be significant, ranging from a gritty, burning sensation to moderate pain. This is because the outer layer of the cornea has been completely removed and needs to regenerate, which takes about four to five days.
Success Rates
PRK delivers strong visual outcomes for most patients. In a prospective study from a tertiary eye center, 92% of patients with low to moderate nearsightedness achieved 20/20 uncorrected vision at 12 months, and 88.5% of those with high myopia reached the same level. Every patient in the study achieved at least 20/40 vision, which is the standard for driving without glasses in most places.
The percentage of patients who need a retreatment (enhancement) after PRK averages about 6.8%, with studies reporting ranges from roughly 4% to 21% depending on the severity of the original prescription. Higher prescriptions carry a greater chance of needing a second procedure.
Risks and Complications
The most discussed complication of PRK is corneal haze, a mild cloudiness that can develop in the healing cornea. Two patterns exist: an early type that appears one to three months after surgery and typically fades within a year, and a later form that can be more persistent. Haze rates are closely tied to how strong the correction was. In patients with low myopia, haze occurred in less than 2% of cases. In the high myopia group, that figure rose to about 8.6%.
Regression, where the eye gradually drifts back toward its original prescription, is another possibility. One study tracking 371 eyes found that regression occurred mostly during the first 18 months, then stopped. At long-term follow-up (7.5 years), only 4.3% of those eyes needed retreatment. A separate analysis of 150 eyes with regression found it occurred at a rate of about 19%, with higher original prescriptions and greater corneal surface irregularity being the main risk factors.
Other potential issues include temporary halos or glare around lights at night, dry eye symptoms during healing, and, rarely, infection. Serious vision-threatening complications are uncommon.
Who Is a Good Candidate
PRK is often recommended over LASIK for people with thinner corneas, since no tissue is used to create a flap. It’s also a good fit for people with jobs or hobbies that increase the risk of eye trauma, since there’s no flap to worry about being dislodged later. People with certain corneal surface conditions may be better candidates for PRK as well.
PTK candidates are typically people dealing with recurrent erosions that haven’t responded to other treatments, corneal dystrophies causing vision problems, or superficial corneal scars. The condition needs to be located in the front portion of the cornea for the laser to reach it effectively.
Both procedures require a stable eyeglass prescription, healthy eyes aside from the condition being treated, and realistic expectations about the recovery timeline. For PRK in particular, patience during the weeks-long visual recovery is important, since the results are excellent but not instant.