Types of Eye Surgery

Overview: Types of Eye Surgery

There are many different types of eye surgeries. This article focuses on procedures that correct your vision, along with common eye surgeries that treat certain eye diseases.

Types of Corrective Eye Surgeries

Refractive surgery refers to procedures that correct your eyesight if it is the result of refractive errors, which include:

• Myopia (nearsightedness)
• Hyperopia (farsightedness)
• Astigmatism

LASIK (laser in-situ keratomileusis)

LASIK is a type of laser refractive surgery. One feature that sets LASIK apart from other laser refractive surgeries is that LASIK involves the creation of a corneal flap on the surface of your eye, which reduces recovery time and discomfort after surgery. The flap is created by a laser or microkeratome (a special surgical blade). 

PRK (photorefractive keratectomy)

PRK is another form of laser refractive surgery that delivers comparable visual results to LASIK. However, PRK does not require the formation of a corneal flap. Instead, the surgeon removes the upper layer of tissue in your cornea (epithelium) using an alcohol solution and surgical tools, before applying the laser. As a result, there are some key differences between PRK and LASIK:

• PRK involves a longer recovery time
• More discomfort during recovery with PRK
• PRK may be better for people with high prescriptions or thin corneas
• PRK is preferable for people engaged in high-impact activities such as contact sports, due to risk of flap dislocation with LASIK
• PRK typically costs less than LASIK

LASEK (laser subepithelial keratomileusis) and Epi-LASIK

These procedures are modified PRK and LASIK techniques. LASEK involves using an alcohol solution to loosen the corneal epithelium and form a thin flap, significantly thinner than that of LASIK. 

Instead of alcohol, epi-LASIK uses a mechanical epithelial separator to create a thin flap. Avoiding the use of alcohol preserves more of the epithelial tissue. 

Benefits of these procedures include:

• Less discomfort during healing versus PRK
• Lower risk of flap complications versus LASIK
• Thinner corneal flap versus LASIK, more suitable for thin corneas

Small Incision Lenticule Extraction (SMILE)

Small incision lenticule extraction is a relatively new procedure that corrects myopia. During the process, a laser creates a small disc of tissue within the inner layer of your cornea. Then, the surgeon removes this tissue, called a lenticule, via a small incision on your cornea.

Some surgeons favor SMILE over LASIK because there is no corneal flap involved, resulting in a more stable cornea and less dry eye. Although SMILE may be less invasive, other surgeons feel that more experience with this technology is needed before they can recommend SMILE over LASIK.

In the United States, SMILE cannot treat hyperopia and astigmatism.

Radial Keratotomy (RK)

Before laser eye surgery was widely available, radial keratotomy was a procedure to correct low to moderate amounts of myopia. RK gained popularity in the 1980s but is now considered obsolete. 

During this procedure, the surgeon makes several incisions on your cornea in a radial pattern, similar to bicycle spokes or slices of a pizza. These incisions flatten your cornea to correct myopia. Most people who receive RK cannot have LASIK but may be eligible for PRK if they experience vision changes.

Astigmatic Keratotomy (AK) and Limbal Relaxing Incisions (LRI)

Similar to radial keratotomy, these procedures include making incisions on the cornea to flatten the tissue. Astigmatic keratotomy and limbal relaxing incisions can correct lower amounts of astigmatism and are often performed after cataract surgery or corneal transplants. 

The surgeon makes incisions where the cornea is steepest. LRIs are more common than AK. One reason is that LRI incisions are closer to the edge of your cornea, resulting in better vision and less glare.  

In modern cataract surgery, these procedures may be replaced with laser refractive surgery or toric intraocular lens implants.

RLE (refractive lens exchange surgery)

This procedure involves the same steps as cataract surgery. The difference is that these patients do not have cataracts, but rather, their natural lenses are still clear. 

During surgery, your natural lens is replaced with a permanent intraocular lens implant (IOL) that corrects your vision. There are many types of lens implants available, depending on your prescription and visual needs.

RLE may be suitable for:

• People with thin corneas who may not be eligible for laser refractive surgery 
• People with higher prescriptions, especially moderate to high hyperopia or astigmatism

Another benefit of this surgery is that you do not have to worry about developing a cataract when you are older.

PRELEX (presbyopic lens exchange)

Presbyopic lens exchange is a type of refractive lens exchange surgery. While RLE can be performed on younger people, PRELEX focuses on correcting the near vision in people over age 45. Typically, this is the age when people experience presbyopia, which is the loss of ability to focus at near.

The surgeon corrects both the distance and near vision so that you do not need reading glasses or other corrective lenses after surgery. There are a variety of intraocular lens implant (IOL) options:

• Multifocal IOL is similar to progressive eyeglasses, with multiple zones of focus to provide distance and near vision
• Accommodating IOL is a flexible lens implant that can adjust its focus, similar to your natural lens before presbyopia
• Monovision is a technique in which the surgeon places an IOL in one eye to correct your distance vision, and another IOL in the other eye to correct the near vision

Phakic Intraocular Lens Implants (Phakic IOL)

Unlike a refractive lens exchange, phakic IOLs leave your natural lens in place. This surgery is an excellent option for people with high myopia who may not be candidates for laser refractive surgery. 

A benefit of this procedure is that the phakic IOL may be removed later if needed. For example, if you receive a phakic IOL but develop cataracts, the surgeon can remove the phakic IOL before performing cataract surgery.

There are two main types of phakic IOLs:

• Anterior chamber phakic IOL is inserted into the eye between the cornea and iris
• Posterior chamber phakic IOL is inserted behind the iris, in front of your natural lens

Types of Keratoplasty Surgeries

Keratoplasty refers to surgeries performed on the cornea. The following procedures correct various refractive errors. 

Conductive Keratoplasty (CK)

This is a noninvasive procedure to correct mild hyperopia and presbyopia without the use of lasers. Some people undergo conductive keratoplasty to reduce or eliminate the need for reading glasses. 

CK uses a probe tip to deliver radiofrequency currents to your cornea, which shrinks the peripheral areas of the cornea. As a result, the cornea steepens in shape, which reduces hyperopia and improves near vision symptoms of presbyopia. CK can be performed after LASIK or cataract surgery if additional vision correction is necessary.

Laser Thermal Keratoplasty (LTK)

Similar to conductive keratoplasty, laser thermal keratoplasty uses a holmium laser to shrink the corneal tissue, correcting low to moderate hyperopia. Unlike LASIK, this is a noncontact procedure, meaning there is no cutting into the cornea or other direct contact. 

Automated Lamellar Keratoplasty (ALK)

Automated lamellar keratoplasty corrects severe myopia or low hyperopia without the use of a laser. Similar to a LASIK procedure, the surgeon uses a microkeratome to create a flap on your cornea. Instead of using a laser to reshape the cornea underneath the flap, the surgeon removes a small disc of corneal tissue before replacing the flap.

Since safer and more reliable refractive surgeries are currently available, not many surgeons perform ALK.

Other Common Types of Eye Surgeries

Diabetic Retinopathy Surgery

Diabetes causes bleeding, fluid leakage, and abnormal blood vessel growth in your retina, which is the sensory tissue lining the back of your eye. Mild diabetic retinopathy does not always require treatment. 

However, more severe cases may require treatment, such as:

• Laser treatment helps stop bleeding and leakage from blood vessels. This procedure is performed in the peripheral areas of the retina.
• Anti-vascular endothelial growth factor (anti-VEGF) eye injections help prevent abnormal blood vessel growth and reduce fluid swelling in the central part of your retina, a condition called macular edema.
• Steroid injections also treat macular edema.
• Vitrectomy is a surgery performed when the bleeding or fluid swelling cannot be controlled with other treatments.

Laser Cataract Surgery

Traditional cataract surgery involves a procedure called phacoemulsification. First, the surgeon makes an incision in your cornea. Then, an ultrasound device is inserted through the incision into your eye. Ultrasound waves break up the cataract into small parts before a suction device vacuums the pieces out of the eye.

Laser cataract surgery incorporates a laser to replace some steps of phacoemulsification: 

• Instead of a surgical blade, the laser can make an incision on the cornea.
• The laser can create an opening in the capsule, which contains the cataract.
• The laser softens the cataract, which uses less energy than ultrasound and is less disruptive to the eye.

Laser Glaucoma Surgery

There are several types of treatment for glaucoma, including laser procedures. Laser glaucoma surgery is designed to lower the eye pressure by increasing the amount of fluid draining out of the eye.

The two primary forms of laser treatment are:

• Trabeculoplasty involves lasering the tissue in the angle, which is the structure that controls fluid drainage out of the eye.
• Iridotomy uses a laser to create a tiny hole in the periphery of your iris, creating an opening for fluid to flow through. This procedure is often performed if you have narrow angles and are at risk for angle-closure glaucoma.

Trabeculectomy

Trabeculectomy is another form of glaucoma surgery that lowers eye pressure. During this procedure, the surgeon creates a small flap in your sclera, which is the white part of your eye. This opening serves as a fluid channel.

The sclera is covered by a tissue called the conjunctiva. The surgeon uses this tissue to form a bleb, which acts as a reservoir for fluid draining out of the eye. The upper eyelid hides the bleb so it is not visible to others.

Macular Degeneration Surgery

There are two main types of age-related macular degeneration (AMD), dry and wet AMD. The dry form is an earlier stage of the disease, and there are no specific treatments other than nutritional supplements.

Wet AMD is more advanced and causes significant vision loss as abnormal blood vessels start to leak into the macula. Treatment for wet AMD includes:

• Anti-vascular endothelial growth factor (anti-VEGF) eye injections are the primary form of treatment.
• Photodynamic therapy (PDT) incorporates a drug called verteporfin to seal leaking blood vessels. Verteporfin is injected into your veins, and once it reaches your eye, the doctor uses a laser light to activate the verteporfin.
• Laser treatment is no longer widely used because the laser can damage the macular tissue and cause vision loss.

Intacs (Intracorneal Ring Segments)

Intacs corneal implants primarily treat keratoconus, a condition where your cornea progressively steepens and thins out. Because of the irregular shape of their cornea, many people with keratoconus do not see well with glasses and contact lenses. 

Intacs improves vision by flattening the cornea to reduce myopia and astigmatism, possibly eliminating the need for glasses or contacts. The implants are two crescent-shaped pieces of plastic that are placed inside of your cornea. If necessary, the surgeon can remove the implants or replace them with thicker implants if more vision correction is needed.