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radial keratotomy

What was Radial Keratotomy?

RK, short for radial keratotomy, was a process that involved making incisions in the cornea to correct a patient’s vision. The aim of this procedure was to changes the cornea’s curvature, which resulted in the cornea being flattened out, which corrected myopia.

While the procedure isn’t performed much these days, people that did undergo it would receive a thorough eye exam before any action was taken. Some of the things that would be measured and recorded include astigmatism, the corneal curvature, the cornea’s thickness and intraocular pressure. Your eyes would be examined for signs of potential future problems as well as for diseases.

After the above info was taken, it would be entered into a computer program, alongside the patient’s age and sex. The programs used provided a range of info about the incisions, including the number of incisions to be made, the depth, position and the length of the incisions.

A series of between four and 16 incisions, sometimes more, were made in the cornea’s outer portion or in the mid-periphery. A knife shaped like a diamond was often used to make the incisions, which do not have an impact on the normal viewing zone of one’s eyes. Also, major anesthesia was not required to undergo the procedure, but local anesthesia was used because this is what made the procedure nearly painless.

When the patient became comfortable and their eye became numb, the next step was to put a lid speculum in place, as this causes the eyelids to retract. The center of the eye was then marked, but before any incisions were made, the knife that was used was set under the microscope. Accuracy was ensured because a guard is on the instrument.

The diamond shaped instrument was preferred over steel ones. This is because results tend to be unpredictable with steel instruments. At least that’s the opinion of many surgeons that performed the procedure back in the 1980s and 1990s.

Additional incisions may have been required if the patient had an astigmatism present. If the astigmatism was severe, then the incisions were made in a specific manner, similar to the pattern of a step-ladder. The incisions were placed in a perpendicular direction, right towards the cornea’s steepest curvature. What this did was create a new surface on the cornea.

Side Effects From RK

There were side effects that occurred from RK. However, they were relatively rare. That being said, some of the rare and potential side effects included:

  • Vision that fluctuated, which was especially the case during the first month or two following the surgery.
  • A cornea that was weaker and was at risk of rupturing if it was hit directly.
  • Infection
  • Sensitivity to light
  • Difficulty getting contact lenses into one’s eyes

At one point in time, radial keratotomy was frequently used to correct myopia. However, more advanced and effective procedures have come along and RK is not widely used anymore. Some of the procedures that replaced it include Lasik, PRK and Lasek.

The Challenges of Cataract Surgery after Radial Keratotomy

In the 1980s and 90s, there were a large number of patients who had radial keratotomy who now have developed visually significant cataracts. It has been found that even those who have mild cataracts can experience significant aberrations sooner than would otherwise be expected. For several reasons, the complications can be difficult for these patients because their IOL implant calculations may not be accurate and the surgery is challenging. This can prolong the post-operative recovery. In addition, the patients are often intolerant of refractive errors.

IOL Selection

There has been a number of techniques and formulas used for calculating the IOL power in these patients. The conclusion is that there simply isn’t a single method that can consistently yield excellent results. One of the biggest errors is in overestimating the corneal power. This often leads to an implantation that has lower power and post-op hyperopia. A high percentage of these patients have lived with myopia their entire life and this can lead to hyperopia which is especially bothersome and uncomfortable. The remedy to this requires that more myopic results be targeted.

A number of the patients that most eye doctors deal with have no old records and when that is the case they will calculate the corneal power by using a method proposed by Dr. Robert Maloney. This method takes the central corneal power as its measured by topography, and in this way, it doesn’t depend on history. This works in combination with the anterior corneal power along with posterior corneal power. When you convert the topography back to the interior and then subtract the posterior corneal power, it allows an eye doctor to reasonably estimate the IOL calculations.

Because most of the patients have irregular corneas, most eye doctors try to avoid multifocal IOLs and use single focus lens implants instead. Aspheric IOLs are often a good choice for these patients because of the corneal aberrations they have. When you implant a negative spherical aberration it can offset the positive spherical aberration. When this is the situation it is my preference to use the Advanced Medical Optics Tecnis IOL because it works well to offset large degrees of corneal positive aberrations. On the other hand, when the degree of irregularity is unknown, then I choose to use the SofPort Advanced Optics by Bausch & Lomb. This is known as the ‘Do No Harm’ IOL.

Intraoperative Considerations

During surgery, it is common for the RK incisions to be weak and that makes them susceptible to opening. When incisions are made it’s necessary to avoid intersecting with the existing RK incisions. If not, it could cause substantial fluid leakage. When a patient has previously had 8 cut RK the corneal incisions can be done in between the existing incisions. It’s more difficult for patients that have had 16 cut or more because it’s not easy to avoid those incisions unless a scleral tunnel incision is used.

Most eye doctors like to use lower flow along with a lower bottle height and the smaller phaco needle because it’s more gentle on corneas that are weakened and it helps to ensure that the inflow of fluid is more than the outflow. It is important to be careful not to open RK incisions during the surgery because it could cause instability of the anterior segments and there is a risk of capsule rupture. To check for leaks at the end, most eye doctors paint the cornea with fluorescein dye as this can be easily sutured before the patient is taken from the operating room.

When these techniques are appropriately applied they can yield a positive result. These patients are not as easy as some others, but the end result can be one they are satisfied with. As these patients are typically demanding, it makes using these techniques imperative.

Radial Keratotomy (RK) – Correcting Vision Prior To Laser Eye Surgery

We are very fortunate these days to have the opportunity to benefit from several advanced laser eye procedures. There are millions of individuals all over the world who have already benefited from the safe, accurate, and fast results that have been introduced into their lives thanks to laser eye surgery.

Although it might seem as though laser eye surgery has existed forever, actually it has only been a fairly common procedure for about 20 years. Before laser surgery, there was a different widely used vision correction procedure that is called radial keratotomy.

Correcting Vision with Diamond Blades

Radial keratotomy involved a surgical diamond blade being used by an ophthalmologist. That might sound scary, but thousands of individuals had this procedure performed prior to laser eye surgery being available and were very happy with the results they received.

This procedure corrected short-sightedness (myopia) only, and it involved a series of incisions being created that formed a ‘radial’ pattern – similar to cutting a pizza. The deep cuts, unlike laser eye surgery, reshaped the cornea effectively.

Radial keratotomy may involve 32, 16, 12, 8, or 4 incisions being made into several different orientations and patterns that are based on a surgeon’s style and training, as well as refractive errors.

In contrast to laser eye surgery, where the procedure is done on both eyes and is performed as day surgery, individuals who had the radial keratotomy procedure performed usually had to stay in the hospital overnight. The vision of one eye was corrected, and then the second eye would be corrected within a month. This left many people in the unusual position of one eye having nearly perfect or perfect vision while the other eye had blurry short-sightedness.

Radial Keratotomy History

The initial refractive surgery attempts where incisions were made in the cornea occurred during the 1930s. That was when Tsutomu Sato, a Japanese ophthalmologist, conducted his first experiments on the posterior and anterior keratotomy. He continued his experiments after World War II but did not achieve reliable results.

Progress next occurred as a result of an accident. In 1974 Svyatoslav Fyodorov, a Russian ophthalmologist removed glass from a boy’s eye following a bicycle accident. Upon impact his glasses shattered and glass particles lodged inside of his eye.

Fyodorov performed a surgical procedure attempting to save the boy’s vision and made several radial incisions in the eye during the process, which extended into a radial pattern going from the pupil to the cornea’s periphery, which ironically, were similar in form to a bicycle wheel’s spokes.

Fyodorov removed the glass, and then after giving the wounds some time to heal, he re-examined the eyes and was surprised to find that the boy’s vision had made a significant improvement. His visual acuity, in fact, was better than it was prior to the accident. This discovery was the origins of the radial keratotomy procedure.

Although radial keratotomy did turn out to be very popular and reasonably successful, especially during the 1980’s, the main limitation that it had was that the procedure’s success relied heavily on the surgeon’s skill. The procedure may have been more successful. However, laser eye surgery proved to be a technically superior alternative.

Radial Keratotomy Recovery

To ensure proper healing, good post-surgical care was necessary. Despite that, many individuals were eager to throw out their contact lenses or glasses, and most people did experience good visual results.

However, radial keratotomy definitely didn’t have the same benefits that laser eye surgery can offer, either in the long term or short term.

What occurs later?

Individuals who have radial keratotomy performed might not have had any issues following surgery. Some other might develop certain visual problems like night vision loss or halos.

After an individual had the radial keratotomy procedure performed, they were unable to undergo laser eye surgery after it became available. It is something they might have considered if they were not satisfied with the result they received from radial keratotomy. However, it wasn’t possible to have laser eye surgery due to the fact that both corneas top layers were incised.

Most importantly, anybody who had radial keratotomy previously and needs cataract surgery now will require surgical assistance. That doesn’t mean that they can’t have successful cataract surgery. It just means that the surgeon will have to consider a number of different factors when planning the patient’s surgery.

Like with anybody who has laser eye surgery performed, anybody who had radial keratotomy and is in their late 40’s or 50s is going to need to use reading glasses invariably, due to presbyopia.

However, there are numerous individuals who have undergone the superseded vision correction procedure. Although laser eye surgery does provide far superior long-term outcomes, radial keratotomy at the same was considered to be a very effective refractive procedure.

Is LASIK An Option After A Prior Radial Keratotomy Procedure?

Here at Fusion Eye Care in Raleigh, NC, one of the questions we often get asked is about the possibility of LASIK surgery after RK has been performed. More often than not, here’s how the question is usually asked:

“Dear Dr. Bassiri, I am currently around 60 years of age and underwent successful radial keratotomy surgery back in the 1990s to address my nearsightedness. Regrettably, I am now in need of corrective lenses once again. Putting it bluntly, can a prior radial keratotomy patient become a candidate for LASIK corrective surgery? It is my preference to have my vision corrected a second time to prevent a need for the wearing of corrective lenses, at least for the bulk of the time. My medical background makes me fully aware of the fact that every case is different. I merely wish to know if this idea is worth pursuing.”

And while every patient’s case is different, in general, here’s how I typically respond:

“It can be the case that a prior radial keratotomy patient is a candidate for photorefractive keratectomy (known as PRK). This procedure is somewhat akin to LASIK, though LASIK itself can be difficult for such patients given the fact that radial keratotomy cuts are not always compatible with the LASIK flap. A PRK procedure has the potential to be successful in addressing refractive error following radial keratotomy. However, given the age factor involved, the ideal option may be to wait a bit and have cataract surgery or, in the alternative, a refractive lens exchange procedure (RLE).

RLE is similar to a cataract procedure in that the crystalline lens that evolves into a cataract with age is swapped for a corrective implant lens. Many implant options exit to help correct a patient’s vision. Your surgical professional will be able to explain the possibilities and make a sound recommendation for your specific needs. The main takeaway to keep in mind that options are available to further improve your vision, even though you have already undergone radial keratotomy.”

With that said though, we highly recommend that if you find yourself in this exact situation, that you please schedule an appointment to come by our office here in Raleigh so that we can do a thorough analysis to determine the best course of action for you. To do so, please call our office at (919) 977-7480.

Looking At The Post-RK Hyperopic Shift – PART 2

As discussed in the last article on the post-RK hyperopic shift, the three options most practiced these days to address post-RK surgery issues are Cataract Surgery, LASIK, or PRK.

LASIK might sound like a good idea, and many patients ask about it, because it is the “in” eye treatment using eye surgery that has held up to scrutiny for a couple decades now, however most eye doctors won’t recommend this option in many situations. The problem with using LASIK after RK is that there’s potential for an irregular astigmatism to develop because of how LASIK creates a “flap” to work. Generally speaking, RK & LASIK are completely incompatible. One of the huge problems with mixing these is that it involves horizontal slices versus vertical. That’s never a good idea in the eye. It’s at least flirting with a level of disaster most eye doctors do not recommend.

PRK is often a better option, although once again this is a case by case basis and that’s the best surgical option available. Getting to 100% vision is not going to be possible with modern technology. Careful study of the patient has to be done in order to see if the previous incisions are stable or are spreading over time. Obviously, the latter situation is not great.

Even when going in with PRK many eye doctors talk about the need to properly clean incisions with a Sinskey hook, and then be prepared to suture the incisions shut when possible to hold those incisions together, tighten the eye, and hopefully that extra tightness might result in undoing some of the problems that many patients experience. If some reversing of the hyperopia that has been caused can be done, that’s a victory. Treatments that focus on steepening the cornea are often preferred over any type of clear lens exchange. This often leads to much better results, as well.

Patients need to be realistic, and doctors need to give them the proper idea. Even if things go well, there will be a slow hyperopic shift over time. Glasses will be needed for long-distance viewing, and there isn’t likely to be anything that is going to stop that slow but steady shift towards emmetropia. While surgical correction is possible, there’s no getting perfect vision and in many cases even getting back to the vision they had in their 20’s or early 30’s just isn’t going to happen. There are too many recurring issues that we currently don’t have the medical technology or ability to fix.

Finally, cataract surgery is a potential last-ditch option usually based on the age of the patient. There are several special considerations that must be taken before going this route, and an understanding that an immediate heavy hyperopic shift may take place but after two months or so the patient may go plano to bring back the more steady vision. It may or may not be what they were hoping for, but it will get them the best they can get at that point.

There are some new treatments that have been touted as potential options such as CXL (corneal collagen crosslinking) which potentially can improve stability of the cornea but not much is known about this treatment to this point so while there is potential it is also still controversial since not a lot is known about the potential long-term issues or effects this surgical treatment might have on patients.

That said, if PRK, cataract surgery, and/or CXL have been tried and haven’t stabilized things, then a full out transplant might be the only viable option left at this point until more medical advances are made.

Looking At The Post-RK Hyperopic Shift – PART 1

While medical science is advancing in many areas, unfortunately for post-RK hyperopic shift there are very few surgical options. Even among those limited options, none can factually claim to reverse hyperopic progression. While this can be a depressing initial thought, there are some new techniques that might be able to help effectively offset some of the diurnal fluctuations that take place.

There’s no denying that a large percentage of radial keratotomy (RK) surgeries don’t have a happy ending. Up to 40% of the patients who must undergo this surgery end up with hyperopic shifts. This was a surgery that became very popular in the early 1990s using four to eight minor incisions in order to flatten the cornea. This seemed to create some exceptional results at first. However, highly myopic patients would need re-treatments that sometimes would result in 30 or more incisions.

In the mid-1990s published studies came out in the medical community showing surgeons that there were some really serious potential long-term issues that came with RK as a treatment choice. The problem was that RK just never seemed to be a one-time treatment. RK would need to be re-administered after a hyperopic shift, but then RK would flatten the cornea, causing a hyperopic shift. The situation didn’t just stay stable, either. It was progressive and over time could progressively get worse. That led to a lot of angry patients, a lot of miserable patients.

Doctors and surgeons noticed this very quickly, many of them before the official medical reports came out confirming this fear. By the mid-1990s even many of the optic surgeons who had started performing RK in the early 1990s had abandoned it by the middle of the decade. Stopping these procedures as a first effort surgery didn’t stop the problem. Many of the early patients who were in on the RK trend were in their early 30’s in the early 1990’s and now they’re in their 50’s. Most of them have glasses, most of them are unhappy with their current vision, and most frequently need further treatments (and experience further discomfort) because of presbyopic issues or latent hyperopia post-RK.

Making treatment harder for physicians, and often harder on patients, is the fact that patients often have a major issue known as “diurnal fluctuations.” In fact, there can be a notable couple of diopters’ worth of difference. In plain English, that means some serious complications. Many of the corneas are extremely flat (unhealthily so) and treatment goals may vary a bit but however the treatment goes with each individual, RK related hyperopia is a problem that often keeps on returning regardless of treatments.

The goal is providing some sort of biomechanical stability in the eye (specifically the cornea) in order to provide better vision for the patient. That stability is almost always missing in a “post-RK” eye. There have been many patients who thought after a treatment they were better for a few months, a year, or even a few years in some cases only to find more problems in the future with the hyperopia returning.

In theory, there are currently three options for surgeons, although not every patient’s case will make them a prime candidate for all three (or any of the three) for that matter. To learn more about these three options, please click here to read the next article.