What is refractive surgery?
Refractive surgery is an umbrella term for various surgical procedures in which the ophthalmologist changes the refractive power of the eye. The point of attack is either the lens or the cornea of the eye. Defective vision such as nearsightedness and farsightedness can be corrected or at least improved by refractive surgery. Refractive surgery is thus an alternative to glasses and contact lenses in the treatment of refractive errors.
When do you perform refractive surgery?
Light entering the eye is refracted by both the cornea and the lens and then passes through the vitreous body to the retina. There, the image of what is seen is formed. The refractive power of the cornea and lens must be exactly matched to the length of the vitreous body, otherwise various refractive errors will occur, which can be treated by refractive surgery:
- Nearsightedness (myopia): The vitreous is too long, causing images in the distance to appear blurry. The patient can see near objects well.
- Farsightedness (hyperopia): The vitreous is too short, causing images near to appear blurry. Objects in the distance, on the other hand, the patient can see sharply.
- Presbyopia: The deformability of the lens of the eye decreases with age. This is the reason why most people over the age of 45 need reading glasses.
- Astigmatism (curvature of the cornea): The cornea is irregularly curved. As a result, what is seen appears distorted.
Exclusion criteria
The methods of refractive surgery are not suitable for every patient. The following circumstances or pre-existing conditions exclude the eye procedures:
- Patient is younger than 18 years
- very thin cornea
- Glaucoma (green star) with pronounced visual field damage
- chronic progressive corneal diseases
- pre-existing corneal damage
- shallow depth of the anterior chamber of the eye (anterior chamber)
- Macular degeneration
Whether eye surgery is an option for you always depends on the type and severity of the vision disorder. Therefore, talk to your treating ophthalmologist about a suitable treatment method.
What do you do with refractive surgery?
Refractive surgery includes various operations on the eye, which are performed using a scalpel or laser. Beforehand, the patient often receives a local anesthetic using special eye drops. Important procedures of refractive surgery in detail:
Refractive Lens Exchange (RLA)
In refractive lens exchange (RLA), the ophthalmologist opens the eye through an incision at the edge of the cornea, crushes the lens with a special ultrasound device and sucks the resulting pieces out of their capsule through the opening. He then inserts an artificial lens made of a flexible material into this capsule. Finally, he sutures the incision made.
The procedure is performed mainly in more severe cases of nearsightedness or farsightedness.
Phakic intraocular lens (IOL)
The use of phakic intraocular lenses (IOL) is similar to a refractive lens exchange. However, the doctor does not remove the natural lens, but simply inserts a second lens into the eye, an implanted contact lens, so to speak.
This form of eye surgery is performed – like the RLA – mainly in cases of more severe nearsightedness or farsightedness.
Intracorneal ring segments (ICR or INTACS)
Intracorneal ring segments (usually made of Plexiglas) are used in patients who have mild myopia and slight corneal curvature. For this purpose, the ophthalmologist mills tunnel-like holes in the cornea into which he inserts the crescent-shaped Plexiglas rings. This flattens the cornea.
Corneal crosslinking
In this procedure, after mechanical removal of the corneal epithelium, the physician drips riboflavin (vitamin B2) onto the cornea. Then the cornea is irradiated with UV-A light for about 10 to 30 minutes (the exact duration of irradiation depends on the intensity of the radiation). The procedure is intended to stiffen the cornea and thereby stop chronic corneal disease.
Corneal crosslinking can be used in the following cases:
- Keratoconus (cone-shaped protrusion of the cornea)
- Pellucid marginal degeneration (PMD; thinning and protrusion of the inferior peripheral cornea).
- thin cornea (e.g. after eye laser surgery)
- Corneal curvature
Corneal implantation
A corneal implant can be used to change the shape of the cornea. Alternatively, it can be used to create an artificial pupil. The doctor inserts the implant into a corneal pocket on the non-dominant eye.
Implantation is usually used in cases of presbyopia. However, the complete elimination of reading glasses is not possible for most patients.
Astigmatic keratotomy
The term refractive surgery also includes keratotomy, i.e. the splitting of the cornea. It serves to compensate for corneal curvatures. Using a special diamond knife, the doctor makes tiny incisions in the cornea, depending on the degree and direction of the corneal curvature. The procedure is often performed at the same time as cataract surgery.
Laser process
There are also a number of laser procedures that can be used to change the refractive power of the lens. Well-known techniques include LASIK (laser in situ keratomileusis), LASEK (laser epithelial keratomileusis), and PRK (photorefractive keratectomy).
How the different laser procedures work, for whom they are suitable and what risks they entail, you will learn in the article Eye Laser.
What are the risks of refractive surgery?
Before the patient decides to undergo refractive surgery, the ophthalmologist must inform him about the possible complications of the planned procedure. The probability of such complications is low – the complication rate for refractive surgery is less than 0.5 percent.
Basically, eye surgery can result in the following complaints:
- Glare sensitivity
- Dry eyes
- Eye pain
- Watering eyes
In some cases, refractive surgery is followed by more serious symptoms such as:
- Corneal scarring
- Corneal protrusion (keratectasia)
- Disruption of tear film secretion
- Infections of the eye
- Opacity of the lens (cataract)
- Water accumulation in the retina (macular edema)
- Retinal detachment
- worsened twilight vision
In five to ten percent of the patients treated, the defective vision is not or only insufficiently treated after the operation and a new operation is necessary.
What do I need to keep in mind after refractive surgery?
Whether refractive surgery leads to the desired success also depends on you as a patient. Here are the most important tips:
- Do not rub your eyes for the first few days after surgery. This will help the wound in the cornea to heal better.
- Your doctor will prescribe you special eye drops, which you should use regularly exactly according to his instructions.
- If you notice severe pain or a sudden deterioration of vision, you must consult your ophthalmologist immediately!
Keep in mind that refractive surgery does not always lead to an optimal result immediately. In some patients, a follow-up correction is necessary, which the doctor usually performs with a laser.
