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Monthly Archives: February 2017

Know more about Refractive Eye Surgery

Refractive eye surgery is a type of eye surgery that is used to rectify refractive errors of the eye and decrease dependency on corrective lenses such as eyeglasses and contact lenses. Successful refractive procedures can reduce myopia or nearsightedness, hyperopia or farsightedness, and astigmatism or elongated corneas. A number of different procedures exist for refractive eye surgery depending upon the type and severity of the refractive error.

There are four main types of refractive eye surgery procedures: flap and photoablation procedures; corneal incision procedures; thermal procedures; and implants. Currently, the most common refractive eye surgeries involve the use of lasers to reshape the cornea.

Flap procedures involve cutting a small flap in the cornea so that the tissue underneath can be reshaped to correct the refractive error. LASIK, short for Laser Assisted In-Situ Keratomileusis, is the most popular refractive surgery and is used to correct myopia, hyperopia, and astigmatism. The LASIK procedure involves using a microkeratome or IntraLase to cut a flap into the stroma, moving the flap out of the way, removing excess corneal tissue with an excimer laser, then replacing and smoothing out the flap. LASEK is best suited for individuals with thin or flat corneas. The LASEK procedure uses a small trephine blade to cut into the shallow epithelium, after which the eye is bathed in a mild alcohol solution to soften the edges of the epithelium. The flap is gently moved out of the way so that an excimer laser can remove excess corneal tissue, after which the flap is replaced and smoothed out. Epi-LASIK, like LASEK, involves a shallow cut into the epithelium, but makes use of epikeratome to create a thin epithelium sheet for removal instead of the harsher blade and alcohol.

Photoablation, the second stage in flap procedures, makes use of ultraviolet radiation to remove excess corneal tissue. PRK, or photorefractive keratectomy, was the original laser eye surgery procedure. PRK involves numbing the eye with local anesthetic eye drops, and reshaping the cornea by destroying miniscule amounts of tissue from the surface of the eye. The laser used, an excimer laser, is a computer-controlled ultraviolet beam of light. It burns cool so as not to heat up and damage the surrounding eye tissue.

Corneal incision procedures such as radial keratotomy and arcuate keratotomy use miniscule incisions in the cornea to alter its surface and correct refractive errors. Radial keratotomy, or RK, uses a diamond tipped knife to make a number of spoke-shaped incisions in the cornea. The result of the incisions is that the cornea flattens out, minimizing the effects of myopia. Arcuate keratotomy, or AK, is very similar to RK. The diamond knife is used to cut incisions that are parallel to the edge of the cornea, as opposed to the spoke-shaped incisions of the RK procedure. These procedures have been much less common with the emergence of laser-assisted refractive eye surgeries.

Thermal procedures use heat to correct temporarily hyperopic refractive errors, or farsightedness. The thermal keratoplasty procedure involves putting a ring of 8 or 16 small burns on the eye immediately surrounding the pupil. The application of the heat increases the slope of the cornea, making it steeper, through thermal contractions. There are two main types of thermal keratoplasty. Laser Thermal Keratoplasty, or LTK, is a no-touch procedure that uses a holmium laser. Conductive Keratoplasty, or CK, uses a high-frequency electric probe.

The final type of refractive eye surgery involves the use of implants. Implantable contact lenses, or ICL, can be used to correct severe levels of myopia, hyperopia, and astigmatism. The implants are actually tiny contact lenses that are inserted through a small incision in the side of the cornea. Implants are seated so they sit immediately in front of the eye’s natural lens just behind the cornea. ICL works in conjunction with the eye’s natural lens to refocus light on the retina and produce a crystal clear image.

Each of these procedures has its advantages and disadvantages, and not all individuals are suitable candidates for refractive eye surgery. Individuals who are interested in learning more about surgical options should contact their ophthalmologist for more information about these procedures, as well as inquire about other new cutting-edge procedures. Since ophthalmologic surgery is constantly growing and changing with emergence of new technologies and methods, there are always new techniques in development. As new equipment is developed and methods refined that can improve the success and minimize the side effects of refractive eye surgery, new procedures will emerge to replace outdated techniques.

 

About Contact Lenses

Your vision depends on light beams hitting the retina (the back of your eyeball) at the same point. When the light does not meet at the same point, vision becomes blurred.

To correct this vision problem a lens needs to be placed in front of the eye to compensate. The lens then becomes a ‘perfect’ eye and light beams converge together at the retina.

Even though eye glasses have long provided the needed correction for vision problems, contact lenses were a marvel of science allowing individuals the freedom to forgo the hassle of slipping, fogging and distracting eye glasses. The inside surface of the contact lens is fitted to the shape of your eye so it stays in place. The outer surface is shaped to the corrected curve (as in eye glasses).

Originally, these contacts were made of hard plastic that required saline solution drops on a regular basis to keep moist. They were also prone to ‘popping’ out and causing discomfort when blinking. Newer contacts are made from a soft plastic that allows the eye to ‘breathe’. They are much more comfortable to wear and because of the high water content of the material they require less maintenance during use. Soft contacts cling to the layer of tears covering the cornea and move slightly with each blink. This ensures that the eye stays moist and foreign materials can be safely washed out.

Basically, the purposes of contact lenses are to correct common vision problems like short-sightedness (myopia – when a person can focus on objects close to them but not far away) and far-sightedness (hyperopia – where the individual can see well at a distance but has trouble focusing clearly on print and other close objects). Now even individuals with astigmatism (where the shape of the cornea is elongated) or presbyopia (an age related condition that used to require bi-focals) can find contact lenses to suit their unique needs.

Currently, contacts are now developed in a disposable variety that means no cleaning is required. There are also contacts that can be worn for a week or even a month without being removed and cleaned – great for those who hate the daily hassle.

Many contact lens wearers are experimenting with changing the color of their eyes. While older versions produced harsh colors, new versions of color contacts (which can even be worn by individuals who have no vision problems) can be found in subtle shades and can even change dark eyes to light.

The contacts will be improved in the future. There is even talk of contacts created to prevent conditions like myopia from developing in children. Whatever happens, those with vision problems can count on new solutions being added to the currently available options all the time.

 

Common Questions about Lasik Surgery

What is Lasik Surgery?

Lasik, an acronym for Laser-assisted, is a form of refractive laser eye surgery procedure performed by ophthalmologists intended for correcting vision. The procedure is usually a preferred alternative to photorefractive keratectomy, PRK, as it requires less time for full recovery, and the patient experiences less pain overall.

The Lasik Operation

The Lasik Operation is performed with the patient awake and mobile; however, the patient typically is given a mild sedative and anesthetic eye drops.

Lasik is performed in two steps. The initial step is to create a flap of corneal tissue. This process is achieved with a mechanical microkeratome using a metal blade, or a femtosecond laser microkeratome that creates a series of tiny closely arranged bubbles within the cornea. A hinge is left at one end of this flap. The flap is folded back, revealing the stroma, the middle section of the cornea.

The second step of the procedure is to use an excimer laser to remodel the corneal stroma. The laser vaporizes tissue in a finely controlled manner without damaging adjacent stroma by releasing the molecular bonds that hold the cells together. No burning with heat or actual cutting is required to ablate the tissue. The layers of tissue removed are tens of micrometers thick.

Currently manufactured excimer lasers use a computer system that tracks the patient’s eye position up to 4,000 times per second, redirecting laser pulses for precise placement. After the laser has reshaped the cornea, the Lasik flap is repositioned over the treatment area by the surgeon. The flap remains in position by natural adhesion until healing is completed.

Performing the laser ablation in the deeper corneal stroma and under the Lasik flap fools the cornea into not knowing that it has had surgery. The wound response is muted, thus the patient is typically provided rapid visual recovery and virtually no pain.

Wavefront-guided Lasik

Wavefront-guided Lasik is a variation of Lasik surgery where, rather than apply a simple correction of focusing power to the cornea (as in traditional Lasik), an ophthalmologist applies a spatially varying correction, using a computer- controlled high-power UV laser guided by measurements from a wavefront sensor.

The goal is to achieve a more optically perfect eye, though the final result still depends on the physician’s success at predicting changes which occur during healing.

Nor are wavefront aberrations the factor to degrade vision; especially in older patients, scattering from microscopic particles plays a major role. Hence, patients expecting so-called “super vision” from such procedures may be disappointed.

Surgeons claim patients are generally more satisfied with this technique than with previous methods, particularly regarding lowered incidence of “halos”, the visual artifact caused by spherical aberration induced in the eye by earlier methods.

Although there have been a number of improvements in Lasik technology, a large body of conclusive evidence on the chances of long-term complications is not yet in place. Also, there is a small chance of complications, such as slipped flap, corneal infection, haziness, halo, or glare. The procedure is irreversible.

The incidence of macular hole has been estimated at 0.2% to 0.3%.

The incidence of retinal detachment has been estimated at 0.36%.

The incidence of choroidal neovascularization has been estimated at 0.33%.

The incidence of uveitis has been estimated at 0.18%.

Although the cornea usually is thinner after Lasik because of the removal of part of the stroma, refractive surgeons strive to maintain a minimum thickness in order to not structurally weaken the cornea.

Decreased atmospheric pressure at higher altitudes has not been shown to be extremely dangerous to the eyes of Lasik patients. However, some mountain climbers have experienced a myopic shift at extreme altitudes. Although there are no published reports documenting diving-related complications after Lasik, urban legends that describe eyes that have popped open during scuba diving still persist.

There are also concerns about possible Lasik-related problems with night vision, to the extent that some armed forces around the world advise aspiring air force and special forces personnel not to have the surgery.

About Lasik Eye Surgery

Lasik eye surgery has been big news on the vision front. With many people flocking to have the procedure done it has become one of the most popular eye surgeries. The idea that lasik is a solution for anyone with bad vision also proves that much is unknown about lasik. Before committing to the surgery patients should look into what lasik is and what it can do for vision.

Lasik stands for laser-assisted in Situ Keratomileusis. Lasik is where the surgeon cuts a small flap in the cornea and then uses a laser to reshape the inner area of the cornea. The cornea can be related to many vision issues. Myopia (nearsightedness), Hyperopia (farsightedness), and Astigmatism can all be solved through lasik eye surgery.

Before getting lasik a patient is examined by their eye doctor. During the examination pictures of the cornea will be taken to see what corrections need to be made. The overall health of the patient and patient’s eyes are also considered when deciding if a person is a good lasik candidate. Any conditions, such as dry eye syndrome, may affect a persons ability to get lasik.

After lasik the patient can go home and within a few days is usually recovered enough to daily routine activities. Most people experience success and will see clearly right after the surgery. Some people may experience side effects like night time vision problems and light sensitivity. Rare side effects like infection can also occur, but most often can be avoided by following doctors orders.

Lasik is a fairly new procedure and long term data has not been studied. Some people do require the use of reading glasses as they age even though they have received lasik and achieved good results. The patient should discuss all concerns and expectations with their surgeon before the lasik procedure to ensure they completely understand the process and outcome possibilities.