What is Keratectomy?
Keratectomy is the excision (removal) of a piece of the cornea. The procedure can alter the refraction of the cornea, that is, its focusing power.
There are three common types: keratectomy with an excimer laser, wedge-shaped keratectomy and lamellar crescentic keratectomy. The first such procedure with an excimer laser is used for photorefractive keratectomy (PRK). Wedge-shared keratectomy can reduce astigmatism after keratoplasty or cataract surgery. Lamellar crescentic keratectomy may help with pellucid degeneration or Terrien’s marginal degeneration.
Key Points
- Keratectomy is a procedure that changes the refraction of the cornea.
- There are three main types: keratectomy with an excimer laser, wedge-shaped keratectomy and lamellar crescentic keratectomy.
- Photorefractive keratectomy (PRK) is keratectomy with an excimer laser.
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Understanding Keratectomy
Keratectomy is widely used in eye surgery. PRK is a type of corrective eye surgery that uses a laser rather than a blade to remove corneal tissue. The excimer laser was developed in the early 1970s and modified for ophthalmic use in the early 1980s. It wasn’t until 1995, however, when the Food and Drug Administration approved its use for PRK corrective eye surgery. This delay was due to safety concerns with using lasers to correct vision. With continued safety improvements and refinements, PRK has now become one of the most popular types of eye surgery.
PRK has comparable visual outcomes compared to laser-assisted in-situ keratomileusis (LASIK). Approximately 90% of PRK patients have 20/20 vision one year after surgery. However, there are some key differences. PRK has a longer recovery time than LASIK. Also, PRK is generally preferred over LASIK in patients with thin and/or irregular corneas. The main technical difference between PRK and LASIK is that LASIK creates a corneal flap and then shapes the cornea. Conversely, PRK does not create a corneal flap.
While both procedures are relatively successful, a careful evaluation is necessary to figure out which procedure is right for you.
Why You May Need the Procedure
A keratectomy may be required for many reasons. For instance, PRK can treat refractive errors, such as myopia (nearsightedness), hyperopia (farsightedness) and astigmatism. A wedge-shared keratectomy can reduce astigmatism after keratoplasty or cataract surgery. A lamellar crescentic keratectomy may help with pellucid degeneration or Terrien’s marginal degeneration.
For PRK specifically, an excimer laser is used to alter the cornea’s shape so that it can better focus light rays on the macula. The macula is the part of the retina that is responsible for color vision and visual acuity.
Keratectomy Procedure
Most keratectomy are outpatient procedures, that is, you return home the same day. Prior to undergoing the procedure, it is important to have a thorough evaluation with an eye surgeon (ophthalmologist). If you’re already undergoing cataract surgery, a wedge-shaped keratectomy may be a good option to reduce astigmatism. If you have corneal degeneration with changes in the shape of your cornea, a lamellar crescentic keratectomy may be recommended.
For PRK specifically, your ophthalmologist will evaluate the overall health of your eyes and cornea, along with having a discussion about the visual outcomes. Importantly, the ophthalmologist will make sure your eyeglass prescription has not changed within the last year.
Exclusion criteria for PRK include pregnancy, advanced glaucoma, breastfeeding, visually significant cataracts, eye inflammation or infection, corneal scars, and other serious eye conditions.
There are several techniques for completing the procedure. PRK involves the following steps:
- The surgeon will numb your eyes with eye drops.
- Next, they place a holder in the eye so that you won’t blink or move your head.
- A blade, brush, alcohol, or laser removes the outer layer of the cornea (the epithelium).
- An excimer laser reshapes the cornea for the desired visual outcome.
- Your doctor will prescribe non-steroidal anti-inflammatory eye drops, steroid drops, and antibiotic drops.
- At the end of surgery, your surgeon places a clean, clear contact lens to lower eye irritation during the healing process.
The healing process is longer than LASIK because PRK does not involve a corneal flap and the corneal epithelium is removed.
Possible Side Effects
While keratectomy procedures are relatively safe and well-tolerated by patients, there are some side effects. Patients can develop corneal haze and corneal scarring with blurry vision. Other side effects include eye infections, halos around lights, dry eyes, pain, and light sensitivity. Most side effects are mild and manageable.
