The Mechanism of Eye Surgery


Vision represents one of the five basic senses we have been blessed with and the eyes are the second most intricate organs in the human body after the brain. Our eyes can get strained, infected and are prone to disease, so like all our organs, keeping the eyes healthy is of utmost importance.


You may have heard the megapixel capacity of the latest digital camera or smartphone camera being touted in its marketing campaign. A camera does not even come close to the equivalent of megapixels that naked eye can detect. If a person has 20/20 vision i.e. normal faculty of seeing and if they have a full perspective, it is estimated that their eye can see 576 megapixels. That dwarfs the capacity of any camera on the market and lays further emphasis that the eyes are a genetic wonder. In reality though, given the complexities of vision, the real measure could be much more.

Woman with GlassesLike all organs in the body, the eyes are also prone to disorders. The most common of these is a weak visual perception. This is when the eyes have a deficiency. In such cases, patients can either opt for glasses or they can avail the surgical route and undergo that procedure. We will analyze the basics of how the latter works.


Before we look at the popular methods of corrective eye surgery, we will briefly chronicle its history. Refractive eye surgery became prominent in America in the 1980’s. At the time, the procedure was called Radial Keratotomy. The mechanics involved slicing incisions to level the surface of the patient’s eyes in a bid to rectify their nearsightedness. However, the operation was still a work in progress and patients regularly faced issues in the aftermath of the surgery. In particular, those with weaker eyesight experienced fluctuating and night vision dilemmas.

With the passage of time, Radial Keratotomy became redundant as significant advancements were made. Most notably, Photorefractive Keratectomy was successfully performed in the 90’s. It changed the curvature of the patient’s cornea and is still in widespread use in the modern era.

The most common procedure in use today is called LASIK. The acronym means Laser-Assisted In Situ Keratomileusis. When people refer to laser surgery for the eyes, this is what they mean. The process is essentially an expedited edition of Photorefractive Keratectomy since the patients feel negligible discomfort and is able to recover vision within hours of the operation. Both procedures are used today based on the individual case.

Photorefractive Keratectomy

Photorefractive Keratectomy is a refractive procedure that can fix myopia (nearsightedness), hyperopia (farsightedness) and astigmatism (blurred vision) respectively. It is the predecessor to LASIK, which we will discuss further below.

Photorefractive Keratectomy is recommended when an eye specialist, usually an ophthalmologist, deems that the patient does not qualify for LASIK. The actual procedure lasts mere minutes and consists of the removal of the cornea’s outer layer. The laser then molds the exposed cornea to rectify the patient’s vision.

In terms of gauging the suitability of patients for the procedure, they must be evaluated with an eye test. This includes observation of the size of their pupils, moistness of their eyes, the corneal curvature and thickness as well as the medical history of the patient.

A benefit of Photorefractive Keratectomy is that more patients can be treated. For instance, a case of dry eyes or irregular astigmatism would not be entitled to LASIK surgery but can go for this instead.

The reshaping of the cornea is done through an excimer laser which enables light to enter into the retina properly. The narrow film of the cornea called the epithelium is discarded before the corneal tissue is adjusted. The reason it takes patients a few days to recover vision is that the epithelium grows back gradually.

An alternate of Photorefractive Keratectomy known as LASEK (Laser Assisted Subepithelial Keratectomy), not to be confused with LASIK, is also available. The only difference is that the epithelial layer is lifted and not removed. Surgical equipment called a trephine is employed to preserve the layer during the procedure.

There are several advantages of Photorefractive Keratectomy. For instance, there is a lesser depth of laser treatment relative to LASIK. Patients with a slender cornea can undergo the procedure and no risk is attached to the process. There are no corneal flap complexities involved. Finally, there is also considerably lesser chance of the cornea’s thickness being affected.


LASIK is a surgical method that also treats nearsightedness, farsightedness, and astigmatism. A thin flap is created in the cornea using a microkeratome blade or femtosecond laser. The ophthalmologist who performs the procedure folds the flap backward to expel the corneal tissue found below the flap. This is executed using excimer laser technology.

Once the tissue is removed, the flap is placed back in its original position. For those struggling with nearsightedness, LASIK flattens the cornea, which is too steep. Patients with far sight are the opposite since they require a steeper cornea. Finally, astigmatism issues can also be resolved since LASIK can fix an irregular cornea also.

Like Photorefractive Keratectomy, LASIK also requires an assessment of the patient beforehand. A specialist will evaluate the patient’s eyes, what procedure is best suited for them and the extent of laser ablation i.e. the removal of the corneal tissue needed. Additionally, the doctor will run a conscientious background check which will entail your medical history to ensure that you are the ideal candidate for LASIK. There are multiple cases where patients are not deemed fit for LASIK but they can undergo a Photorefractive Keratectomy instead.

Moreover, LASIK is an outpatient surgery, which means that patients are not required to stay in the hospital for a number of days. In fact, the actual procedure takes minutes since the surgeon uses a machine to adjust the laser for your particular prescription. While a patient looks at a specific target, the laser emits pulses of light which perform the operation. The patients are only exposed to the laser for mere minutes and do not feel any pain whatsoever. LASIK has a high success rate when it comes to patients. They recover their vision in a few moments and do not warrant any bandages or stitches at all.

Leave a Reply