Refractive Error Surgery
In order to see objects clearly, light waves and images must be focused on the retina after passing through the cornea and lens. The images formed on the retina are sent to the brain via the optic nerve, and this is how we perceive vision. Refractive errors occur when the eye does not properly and accurately focus the light waves, so the image does not fully focus on the retina, resulting in a blurry image.
Types of Refractive Errors:
Myopia (Nearsightedness): In this condition, due to the longer anterior-posterior diameter of the eye or increased curvature of the cornea, the image of objects is formed in front of the retina, making it difficult to see distant objects. A major risk with severe myopia is retinal detachment.
Hyperopia (Farsightedness): This condition, caused by a shorter anterior-posterior diameter of the eye or reduced curvature of the cornea, results in the image of objects being formed behind the retina. The individual sees both near and distant objects as blurry, but the blurriness is more severe for nearby objects. This condition worsens with age as the lens loses its ability to focus.
Presbyopia: In younger individuals, the lens of the eye is highly flexible, and its diameter easily changes to focus on both near and distant objects. After the age of 40, the lens becomes stiffer and loses its ability to accommodate, making it difficult to read or perform tasks up close. This condition is called presbyopia.
Astigmatism: Astigmatism is a very common condition where most people have some degree of it. A normal cornea is smooth and round, with an equal curvature in all directions. Astigmatism occurs when the corneal surface has an irregular curvature. Due to this, light waves are refracted unevenly across the cornea, and images are not sharply focused on the retina. As a result, both distant and near objects may appear blurry.
Methods to Correct Refractive Errors:
Glasses: Wearing glasses is the simplest way to correct refractive errors. Changing the lens prescription is easy and also provides protection from sunlight.
Contact Lenses: Various types of contact lenses are available today. The type of lens selected depends on the type of refractive error and the person’s lifestyle and activities. Contact lenses and glasses focus light onto the retina, improving vision.
Common Refractive Surgery Techniques:
LASIK (Laser-Assisted in Situ Keratomileusis): LASIK is a combination of microsurgery and excimer laser used to treat myopia, hyperopia, and astigmatism. In LASIK, a very thin layer of the cornea is cut using a specialized instrument called a microkeratome. Then, an excimer laser is used to reshape the underlying tissue, and the layer is repositioned. The layer adheres to its original place after a few minutes, without the need for stitches.
FemtoLASIK: FemtoLASIK is one of the newest methods for correcting myopia, hyperopia, and astigmatism. It is the latest innovation in refractive surgery, where the corneal flap is created with a femtosecond laser. The procedure is very similar to LASIK, but the key difference is that femtosecond laser is used instead of a microkeratome to create the corneal flap. FemtoLASIK offers unmatched precision and safety, along with the advantages of faster recovery, reduced pain, and a quicker return to daily activities.
PRK (Photorefractive Keratectomy): In PRK, the outermost layer of the cornea (the epithelium) is removed, and the corneal surface is reshaped using an excimer laser to correct refractive errors.
LASEK (Laser-Assisted Sub-Epithelial Keratectomy): LASEK is a modified version of PRK. In LASEK, an alcohol solution is used to loosen the epithelium of the cornea, which is then removed. The excimer laser reshapes the cornea, and the epithelium is repositioned afterward. This method is rarely used today, as PRK is considered the better option.
These methods allow individuals to reduce or eliminate their dependency on glasses or contact lenses, providing a permanent solution to refractive errors. However, each technique has its specific applications, and it is important to consult an ophthalmologist to determine the best method based on individual needs and eye health.