Lasers in Eye: Types, Uses, and Wavelength Used in LASIK Surgery

Lasers in Eye: Lasers are widely used in modern ophthalmology for treating several eye conditions and performing precise surgical procedures. They allow doctors to perform delicate treatments on different parts of the eye with high accuracy and minimal damage to surrounding tissues.

Understanding lasers in the eye, including their types, mechanisms, and medical applications, is an important topic in ophthalmology. It is particularly relevant for students preparing for medical entrance exams such as NEET PG, where questions related to laser technology in eye treatments frequently appear.

Different types of lasers are used depending on the condition being treated. Some lasers are used to cut or create openings in eye tissues, while others help seal blood vessels or reshape the cornea during refractive surgeries like LASIK. These procedures help treat conditions such as cataracts, glaucoma, and refractive errors like myopia and hypermetropia.

Types of Lasers

Lasers used in ophthalmology are mainly classified based on their mechanism of action. There are three major types of lasers used in eye treatments:

1. Photodisruptive lasers

2. Photocoagulative lasers

3. Photoablative lasers

Each of the lasers in eyes has a specific function and is used for different eye procedures.

Photodisruptive Lasers

Photodisruptive lasers work by creating a small disruption or opening in eye tissues. These lasers are commonly used when a precise cut or hole needs to be created inside the eye.

Two important photodisruptive lasers are:

1. Nd:YAG Laser

The Nd:YAG laser is commonly used to cut the posterior capsule of the lens, a procedure known as posterior capsulotomy. This procedure is often performed after cataract surgery when the posterior capsule becomes cloudy.

Another use of Nd:YAG laser is peripheral iridotomy, where a small hole is created in the iris to improve fluid drainage in the eye. However, this laser is not applied directly to the retina because it may create a retinal hole.

2. Femto Laser

The femtosecond laser is also a photodisruptive laser. It is widely used in cataract surgery and refractive surgeries.

One of its important uses is in LASIK surgery, where the femto laser is used to create a flap in the cornea before reshaping it. It is also used in the SMILE (Small Incision Lenticule Extraction) procedure.

In the SMILE technique, the femto laser cuts a small piece of corneal tissue called a lenticule, which is then removed through a small incision. This removal changes the shape of the cornea and corrects the refractive error.

Photocoagulative Lasers

Photocoagulative lasers work by generating heat that helps seal tissues or blood vessels in the eye. These lasers are commonly used in conditions affecting the retina and glaucoma treatment.

Important photocoagulative lasers include:

• Argon laser

• Diode laser

• Double-frequency Nd:YAG laser

One of the main uses of photocoagulative lasers is trabeculoplasty, where the laser is applied to the trabecular meshwork in patients with open-angle glaucoma to improve fluid drainage.

They are also used in treating retinal vascular diseases such as diabetic retinopathy, central retinal vein occlusion (CRVO), and sickle cell retinopathy. In these cases, laser beams are focused on the retina to seal leaking blood vessels and prevent further damage.

Photoablative Lasers

Photoablative lasers are mainly used in refractive eye surgeries. These lasers remove microscopic layers of tissue from the cornea to reshape it and improve vision. The most important photoablative laser is the Excimer laser.

Excimer lasers include different types such as:

• Xenon Chloride

• Xenon Fluoride

• Argon Fluoride

Among these, Argon Fluoride is commonly used for eye surgeries. This laser is mainly used in refractive procedures such as LASIK, where it reshapes the cornea to correct vision problems like myopia, hypermetropia, and astigmatism.

What is the Wavelength of the Laser Used in LASIK Surgery?

In LASIK surgery, the laser used for reshaping the cornea is the Argon Fluoride Excimer laser, which has a wavelength of 193 nanometers (nm).

This ultraviolet wavelength allows the laser to remove extremely thin layers of corneal tissue with high precision, helping to reshape the cornea and correct refractive errors.

Other lasers used in ophthalmology have different wavelengths, including:

• Nd:YAG laser: 1064 nm (infrared range)

• Femto laser: 1053–1054 nm

• Argon laser: 514 nm

• Diode laser: 780–850 nm

• Double-frequency Nd:YAG: 832 nm

These wavelengths determine how the laser interacts with eye tissues and which procedures they are suitable for.