New technologies remain to broaden options for dealing with keratoconus, myopia, hyperopia

Arising technology in the locations of corneal ring sections, holmium laser thermokeratoplasty (LTK) as well as phakic IOLs is providing brand-new choices for clients suffering from keratoconus, myopia, hyperopia and also presbyopia.

Intacs for keratoconus
At the American Academy of Ophthalmology (AAO) conference in October 2000, Joseph Colin, MD, presented a study of options to penetrating keratoplasty for clients with keratoconus. Of 23 eyes in 20 patients, 60% attained a best-corrected visual acuity of 20/40 or much better. The mean postoperative keratometry was decreased by 3 D.

Daniel S. Durrie, MD, discussed Dr. Colin’s paper, which suggests an option that reinforces the currently compromised cornea rather than further thinning it with LASIK. The idea of using an additive treatment, such as Intacs (KeraVision, Fremont, Calif.), to strengthen the cornea makes a great deal of sense, Dr. Durrie told Health care Optometry Information.

” For several years, we’ve looked at various other choices to corneal transplants for these patients, and also some procedures such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have actually been attempted in the past, but they get rid of part of the cornea in a person population in which we know the cornea is currently thin and weak,” Dr. Durrie stated.

Since the keratoconic eye has a lump in the cornea, Dr. Durrie said, positioning the Intacs insert in the periphery of the cornea will squash the corneal center. This not only decreases the level of myopia, yet reinforces the center bulge, he said. The preferred end result is to delay a corneal transplant for as long as possible.

While the data that Dr. Colin provided show that the treatment is fairly risk-free, claimed Dr. Durrie, the longest term data offered are just 2 years. “Considering the trends in the 3-month, 6-month and also 1-year data, it appears that all clients gained from the treatment, yet we can not state that it stopped the keratoconus for longer than that until more information are built up,” he stated. “Although I remain to do this treatment on isolated situations, I tell clients we don’t recognize the lasting effects and we don’t understand whether it will reduce, quicken or have no impact on the normal course of keratoconus.

” The advantage of this treatment is, if it does not work, you can take the Intacs out and also have actually not compromised the cornea,” he continued. “If the client does require to go on to a corneal transplant, the inserts can be obtained and also not interfere with standard transplant therapy. As a result of the modification fit of the keratoconic cornea, ultimately, individuals become call lens intolerant, and also it is very important to recognize that there is a different to be examined for these patients apart from simply referring them for a corneal transplant.”

Specialists must make sure that individuals recognize that the procedure is not refractive surgical procedure and will not always fix their nearsightedness, stated Dr. Durrie. “I have clients on whom I have actually executed this procedure who have seen 20/40 without glasses, which would be an exceptional result after a corneal transplant, yet they’re still asking yourself why their close friends that have actually had Intacs implanted can see 20/20 when they can not,” he claimed. “That’s why these people require to be educated that this isn’t something that keeps them from putting on glasses. It maintains them from requiring a corneal transplant.”

Hyperopic adjustment with LTK
picture– Post-LTK: The pulses are applied in eight areas, one at the 6-mm zone as well as the other at the 7-mm zone.

Clinical studies have shown laser thermokeratoplasty (LTK) to be a reliable approach of correcting a patient’s hyperopia, and also it might also hold promise for dealing with presbyopia and also overcorrected myopia after LASIK or PRK, claimed David J. Conway, OD, supervisor of refractive surgical treatment for Harvard Vanguard Medical Associates in Somerville, Mass

. Dr. Conway reported on the LTK method as well as its results with hyperopia utilizing the Hyperion laser (Dawn Technologies International, Fremont, Calif.) at the International Society of Refractive Surgery’s Summer Globe Refractive Surgical Procedure Seminar 2000. Dr. Conway was not associated with any Food and Drug Administration (FDA) study; his ISRS presentation was based upon information from the Daybreak FDA investigations as well as lectures he participated in.

When dealing with a person for hyperopia, the practitioner requires to stress the impermanence of the treatment, he claimed. “You need to communicate to the person that this is only a momentary modification in his or her hyperopic condition,” he said. “There is enough regression with this method that the FDA felt it required to refer this.”

Any type of treatment for the adjustment of hyperopia might necessitate retreatment gradually; this is not one-of-a-kind to LTK, said Sandra Belmont, MD, director of the laser vision facility at the Cornell Weill Medical Facility in New York City. “Hyperopia increases as you age,” she claimed. “We have individuals 3 years out who are steady, so I’m extremely satisfied with the outcomes.”

Dr. Belmont informs patients of this possibility, however none have changed their minds. She stated that if retreatment were needed, individuals did incline since the treatment is quick, and also creating a flap, which can lead to complications, is not needed.

The LTK procedure
picture– Security: One scientist has people that are still stable 3 years post-LTK.

The procedure, Dr. Conway claimed, takes 3 seconds to do. Seven pulses are applied in eight places, two times back to back, one at the 6-mm area and the other at the 7-mm area. The FDA study reported that the 612 eyes in 379 people, all older than 40, ranging from +0.75 to +2.50 D, saw no loss in ideal spectacle-corrected visual acuity (BSCVA) after 2 years, he noted.

” No loss of lines of acuity were attributable to the LTK,” he stated. “In contrasting preop to 24 months later on, there was no loss of BSCVA as well as a little bit of gain. We know that myopes and hyperopes are extremely different. Luckily, the resistance of hyperopes is extremely practical in making their satisfaction level really high.”

Before the treatment, individuals get 3 successive administrations of topical proparacaine at 3-minute intervals. Problems were marginal, Dr. Conway noted.

” Clients are usually handled from a convenience point ofview, purely with non-prescription anesthetics to get them through the initial hrs of recovery,” he said. “Since you’re working on the corneal surface, FDA investigators reported a little of foreign-body sensation, which dissipates with time really nicely.”

Regression over time
Dr. Conway said that, while the individual’s skill level stays relatively secure, some regression is evident as the hyperopia boosts in time. “There will be a tiny however significant regression in these patients; it’s simply a matter of whether it goes to a reduced enough degree to justify the client’s price and also experience of undergoing this strategy,” he said. “By contrasting your cycloplegic to your reveal refraction, you can inform whether it exists hyperopia or otherwise.”

A patient’s age factors in to how long the impact of LTK might last, claimed Dr. Conway. “A 50-year-old patient will certainly experience a little bit a lot more impact than a 40-year-old patient, possibly as a result of a bit more dryness or the collagen standing of the cornea,” he claimed.

An off-label indication of LTK is the treatment of presbyopia, stated Dr. Belmont. People who are plano as well as presbyopic may be treated with LTK to accomplish monovision, she said. “Right now, their analysis vision enters focus,” she said. “They get their outcomes right away, and also they’re really pleased keeping that.”

Patients who have been treated for presbyopia commonly will encounter the same level of regression as hyperopes, Dr. Belmont kept in mind. “Presbyopia increases as you age, as does hyperopia,” she claimed. “Patients recognize that this treatment will certainly need to be boosted as their aging demands an increase in the power they’ll need to review. They’re happy as long as you tell them beforehand. I expect this as being the procedure to deal with farsightedness and presbyopia.”

The size of time needed for presbyopic therapy is the same as for that of hyperopia, but the level of power that is applied to the eye is differed, she said.

Overcorrected myopia
The treatment may also verify to be a valid option for improving nearsighted individuals who have been overcorrected with LASIK or PRK, stated Dr. Conway. “This values a lot of factor to consider, due to the fact that you do not need to eliminate any kind of tissue,” he said. “Furthermore, Dawn is submitting for authorization remediation of presbyopia, making people short-sighted in a monovision style. So, I think this will come to be a fairly popular and also typical alternative in this patient populace, as well as we’ll see the amount of even more specialists determine to welcome it.”

LTK is accepted for approximately +2.5 D, claimed Dr. Belmont, and also is presently undertaking tests for therapy approximately +5.6 D.

Refractec’s conductive keratoplasty
Initial professional tests suggest that conductive keratoplasty (CK) utilizing Refractec’s (Irvine, Calif.) radiofrequency technique is most likely safe and also reliable for remedying low to moderate quantities of hyperopia, according to Cent A. Asbell, MD, who presented medical trial information in Miami at the International Culture of Refractive Surgical treatment meeting. “Early outcomes with our data bent on one year recommend that we obtain terrific visual acuity, very good security and also really no unfavorable events, such as loss of vision,” said Dr. Asbell.

CK warms the stromal tissue with an electric present, shrinks the collagen and also steepens the main cornea, Dr. Asbell explained. A high-frequency current is used directly into the peripheral corneal stroma through a shipment tip inserted at 8 or more treatment points. The launch of radiofrequency energy heats the bordering collagen to an uniform temperature level of 65 ° C as well as generates a round impact 500 µm deep vs. a shallower, cone-shaped impact made with the LTK method. A cycle of CK-treated places cinches the cornea and raises its curvature to lower hyperopia.

” The change appears to be irreversible, as well as I believe among the reasons that’s true is that the therapy is delivered straight to the stroma,” said Dr. Asbell. “That’s where you desire the result– not on the endothelium, out the epithelium. It’s an extremely easy medical technique. It’s a non-laser strategy, and it includes one more dimension to what we already can use for refractive surgery– it is an economical procedure,” she included.

CK is consistent
One more key concern, Dr. Asbell mentioned, is that CK is a consistent treatment. “The treatment dimension and the area effect in the stroma are consistent from therapy place to therapy place,” she stated. “Among the essential problems to bear in mind is that the temperature level we get with the CK procedure is always 65 ° and the imprint you make within the outer corneal stroma is always the very same: 100 µm large as well as 500 µm deep within the corneal stroma.”

Dr. Asbell is a detective in the FDA clinical trial of CK. Fellow private investigators at other websites include Marguerite McDonald, MD; Robert K. Maloney, MD; Jonathan Davidorf, MD; Peter Hersh, MD; and Edward E. Manche, MD

. Of the 54 clients on whom Dr. Asbell reported, the normal age was 55, although, she stated, there is a relatively vast array of age amongst the trial’s individuals. To get the test, she clarified, patients had to have uncorrected visual acuity of a minimum of 20/40 or even worse and poor near vision too– common for a hyperope. “We are correcting from 1 D to 4 D of hyperopia, with little or no astigmatism,” Dr. Asbell reported.

She emphasized the rate and also simplicity of the procedure. “This procedure takes 5 minutes per eye. It is a very short procedure; you’re in as well as out very rapidly,” she said. “It is a procedure, but a very simple one. It does not require a skilled professional [to assist] It does not even need an autoclave. The tip, which has to do with the size of a hair, is non reusable.”

Dr. Asbell described the CK nomogram because of this: “The treatment is either at 6 mm, 7 mm or 8 mm. You make a mark on the cornea [showing the size of the treatment zone] The degree of hyperopia you are fixing determines the variety of therapy marks on the cornea. Every one is the same– the same quantity of power and the very same depth within the stroma in each area,” she claimed.

Results appear steady
Of the clients on whom Dr. Asbell reported, 61% achieved uncorrected visual acuity of 20/20 or better 6 months postoperatively as well as 96% were 20/40 or far better at the 6-month mark. One year postoperatively, 62% were 20/20 or far better, and also 92% were 20/40 or far better. “Our outcomes look good and stable. These are very delighted patients,” stated Dr. Asbell. “They really can return to work right away or certainly the following day if they so select. No one takes pain medications.”

Safety and security variables were “generally no,” Dr. Asbell reported. “There was no loss of vision and no corneal edema,” she said. “I think this is mosting likely to be a treatment and also a machine that’s going to be very easy for us to own and to make use of and also an outstanding method to correct hyperopia postop LASIK or to retouch a postop cataract or corneal transplant,” she claimed. “I assume it’s mosting likely to have a great deal of versatility in terms of its usages for dealing with hyperopia as well as perhaps astigmatism.”

Broadened medical trials of LAPR
SurgiLight Inc. (Orlando, Fla.) has actually increased its medical trial studies of laser presbyopia turnaround (LAPR) utilizing its IR-laser in Venezuela, Argentina, Brazil, the Bahamas and also Japan. Likewise, the business has actually arranged setup of the IR-laser in some European countries.

SurgiLight has sent 4 documents to the American Culture of Cataract as well as Refractive Surgery for the May 2001 meeting, where more than 500 instances of LAPR will exist by eye doctors from various countries using the firm’s IR laser.

The firm is in the process of acquiring CE-Mark qualification and selecting numerous worldwide suppliers. It intends to submit additional 510K applications based on certain clearances gotten from Premier Laser Systems. SurgiLight expects to charge a nobility charge of $500 per individual to doctors who use the company’s IR-3000 system in the USA as well as Europe.

B&L NuVita phakic IOL
The third generation of George Baikoff, MD’s, former chamber phakic IOL is stood for with Bausch & Lomb’s (St. Louis) NuVita MA20. The lens is available for myopes varying from 7 D to 20 D. The style is an angle-fixated, single-piece lens, with a curve optical shape as well as a PMMA surface area. The overall optical size is 5 mm and also the total length of the NuVita ranges from 12 mm to 13.5 mm in 0.5-mm increments.

The optic, loop as well as footplate were all redesigned from the previous version to decrease refracted glow, pressure in the angle and better clearance of the iris and all-natural lens. Likewise, the haptics were revamped to get rid of iris retraction. The haptics were made much more adaptable and also, for that reason, led to less pupil ovalization.

In its 2nd generation, the fluorine plasma treatment was contributed to the manufacturing procedure to develop covalent bonds of fluorocarbon radicals with the PMMA surface, which yielded reduced surface area power and incredibly smooth finish. The fluorine therapy greatly enhanced biocompatibility.

In studies conducted by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes implanted revealed a precision rate of ± 0.5 D while 97% showed a precision price of ± 2 D. In regards to safety and security, the BSCVA rates had 47 gaining at the very least 2 lines, as well as no eyes shed lines. The general glare record showed that most people had few troubles.

According to Mike Landreville, international director for refractive innovations at Bausch & Lomb, the company has no intent of introducing the NuVita lens right into the USA for FDA approval or for scientific usage. Rather, the firm is establishing an entire new phakic modern technology for a collapsible former chamber phakic lens. The new phakic lens will certainly not just exist as a brand-new lens, but as part of an entirely brand-new system, completely different from the NuVita line. The brand-new, unrevealed lens system will be of a brand-new product, incorporate a new foldable distribution system and provide a new analysis tool for implantation.

According to Mr. Landreville, the firm plans to have the brand-new system ready for professional use in the USA by this year.

Alcon phakic IOL
A brand-new former chamber phakic IOL was presented by Andrew Maxwell, MD, PhD, at the AAO meeting. The lens has an Acrysof-based (Alcon, Ft. Well Worth, Texas) material and has a number of benefits over other phakic IOLs such as its foldability, which allows the lens to be placed with an incision smaller sized than 3 mm, in addition to an angle-fixated, single-piece layout as well as high biocompatibility. The distance between the cornea and the implant additionally drops in between 2.96 mm and also 3.35 mm, a larger distance than with a few other lenses, he said.

Dr. Maxwell reported that of the 10 implants that have actually been carried out to day, greater than 90% of the people have 20/40 or better uncorrected vision at their postoperative check outs. The mean spherical matching in patients dental implanted so far was– 11.5 D, he said, with a result of– 0.39 D at 1 month and also– 0.8 D at 6 months of residual nearsightedness.

” We see significant enhancement in best-corrected visual acuity, and in all yet one client the postoperative best fixed vision is much better than the best preoperative vision; in most cases, there are 2-, 3- or 4-line increases in best-corrected visual acuity,” Dr. Maxwell stated. “In the one instance where it had not been better, it coincided as the preoperative skill.”

CIBA obtains licenses for IOL
CIBA Vision announced at the AAO meeting that it has actually obtained 3 licenses from Dr. Baikoff for foldable phakic anterior chamber IOL develops to correct not only nearsightedness as well as hyperopia but likewise presbyopia.

” We are extremely excited concerning this brand-new technology,” David Bailey, surgical company system head of state for CIBA, stated. “We think that the MemoryLens material combined with these former chamber styles will be a very successful mix.”

That anterior chamber lens initiative enhances one more refractive implant that was the subject of several presentations in the CIBA Vision booth– the PRL. This posterior-chamber phakic dental implant is being created by Medennium Inc. CIBA Vision took a 10% equity risk in Medennium in July and now holds unique around the world marketing and distribution rights to the lens, which is currently in phase 2 medical tests.

” We are taking a strong position in phakic IOLs,” Mr. Bailey claimed, “as well as we’ll be enhancing that position with more brand-new technology.”
This is the method to treat nearsightedness, ypermetropia and astigmatism (αστιγματισμος ).