Types of Eye Surgery

Overview: Types of Eye Surgery

Eye surgery has advanced swiftly over the last 25 years. The development of new technology, tools, and techniques has turned corrective eye surgery into a common procedure.

"More than 843,000 laser vision correction procedures, including LASIK, PRK, and small incision lenticule extraction (SMILE), were performed in 2018.”

— American Refractive Surgery Council

There are many different types of eye surgeries. This article focuses on procedures that correct your vision. As well as common eye surgeries that treat eye diseases.

Types of Corrective Eye Surgeries

Refractive surgery refers to procedures that correct refractive errors, which include:

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

LASIK (laser in-situ keratomileusis)

PRK (photorefractive keratectomy)

PRK is another form of laser refractive surgery. It delivers comparable vision improvement to LASIK. However, PRK does not require the corneal flap incision. Instead, the surgeon removes the upper layer of tissue in your cornea (epithelium). This is done with 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. This forms a thin flap (significantly thinner than that of LASIK). 

Epi-LASIK uses a mechanical epithelial separator to create the flap. Not using 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. This results in a more stable cornea and less dry eye. SMILE may be less invasive, but some surgeons feel that this technology is too new. More experience may be needed to recommend SMILE over LASIK.

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

Radial Keratotomy (RK)

Radial keratotomy gained popularity in the 1980s but is now considered obsolete. It is a procedure that corrects low to moderate amounts of myopia. RK has now been replaced by laser eye surgery.

The surgeon makes several incisions on your cornea in a radial pattern. This looks like 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)

These procedures also include making incisions on the cornea to flatten the tissue. Astigmatic keratotomy and limbal relaxing incisions correct lower amounts of astigmatism. They 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.  

Now, 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. 

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 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 (age-related farsightedness).

The surgeon corrects both the distance and near vision. You won't 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 aren't 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. It does not require lasers. Some people undergo CK to reduce or eliminate the need for reading glasses. 

CK uses a probe tip to deliver radiofrequency currents to your cornea. This shrinks the peripheral areas of the cornea, steepening the shape of the cornea. The result is reduced hyperopia and improved near vision. CK can be performed after LASIK or cataract surgery for additional vision correction.

Laser Thermal Keratoplasty (LTK)

Similar to conductive keratoplasty, laser thermal keratoplasty uses a holmium laser. This shrinks the corneal tissue to correct 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 Surgery

Diabetic Retinopathy Surgery

Diabetes causes bleeding, fluid leakage, and abnormal blood vessel growth in your retina. 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

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

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. This opening allows 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 (the white 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

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. This condition causes your cornea to steepens and thins out progressively. 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. It may eliminate the need for glasses or contacts. The implants are two crescent-shaped pieces of plastic that are placed inside of your cornea. The surgeon can remove the implants or replace them with thicker implants. This will depend on the type and amount of vision correction needed.

Eyelid Surgery

Eyelid surgery is also known as blepharoplasty or an "eye lift." It is a surgical procedure that modifies the eyelid skin and the skin around the eyes. It can improve the eye’s functioning and give you a more youthful appearance.

Strabismus Surgery

During strabismus surgery, ophthalmologists manipulate muscles around the eye. They may loosen, tighten, or reposition them to improve the alignment of the eyes and vision.

The more extensive it is, the longer the healing period. It may take adults up to seven days to begin feeling comfortable. The eyelids may also be swollen and make it challenging to open the eye shortly after surgery.

Artificial Eye

An ocular prosthesis is an artificial eye that ocularists implant in patients who have lost eyes or have eye abnormalities.

First, the surgeon completely removes the actual human eye. Once the artificial eye is ready, it will fit behind the upper and lower lid. It goes over the shrunken eyeball or orbital implant.