Arising innovation in the locations of corneal ring sectors, holmium laser thermokeratoplasty (LTK) and phakic IOLs is offering new options for people struggling with keratoconus, myopia, hyperopia and also presbyopia.
Intacs for keratoconus
At the American Academy of Ophthalmology (AAO) meeting in October 2000, Joseph Colin, MD, presented a research of options to permeating keratoplasty for clients with keratoconus. Of 23 eyes in 20 clients, 60% accomplished 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 strengthens the already compromised cornea rather than further thinning it with LASIK. The concept of using an additive procedure, such as Intacs (KeraVision, Fremont, Calif.), to enhance the cornea makes a lot of sense, Dr. Durrie told Primary Care Optometry News.
” For years, we’ve looked at other choices to corneal transplants for these clients, as well as some treatments such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have actually been tried in the past, yet they eliminate part of the cornea in an individual population in which we understand the cornea is already thin as well as weak,” Dr. Durrie claimed.
Since the keratoconic eye has a bulge in the cornea, Dr. Durrie said, putting the Intacs place in the periphery of the cornea will certainly flatten the corneal center. This not just reduces the degree of myopia, however reinforces the center bulge, he stated. The wanted end result is to postpone a corneal transplant for as long as possible.
While the information that Dr. Colin presented program that the procedure is rather secure, said Dr. Durrie, the lengthiest term data offered are just 2 years. “Considering the fads in the 3-month, 6-month as well as 1-year information, it appears that all people gained from the procedure, but we can’t say that it quit the keratoconus for longer than that till more information are collected,” he claimed. “Although I remain to do this procedure on isolated instances, I tell clients we do not recognize the lasting results and we do not understand whether it will slow down, accelerate or have no result on the normal course of keratoconus.
” The advantage of this procedure is, if it doesn’t function, you can take the Intacs out and also have actually not damaged the cornea,” he proceeded. “If the person does need to take place to a corneal transplant, the inserts can be gotten and also not interfere with conventional transplant treatment. Because of the change fit of the keratoconic cornea, ultimately, clients become call lens intolerant, and also it’s important to recognize that there is an alternate to be checked out for these individuals other than simply referring them for a corneal transplant.”
Experts need to make certain that patients recognize that the treatment is not refractive surgical procedure and also will not always remedy their nearsightedness, stated Dr. Durrie. “I have clients on whom I have actually done this treatment that have actually seen 20/40 without glasses, which would certainly be an outstanding result after a corneal transplant, yet they’re still questioning why their buddies that have actually had Intacs dental implanted can see 20/20 when they can not,” he said. “That’s why these patients need to be enlightened that this isn’t something that maintains them from using glasses. It keeps them from requiring a corneal transplant.”
Hyperopic adjustment with LTK
photo– Post-LTK: The pulses are applied in 8 places, one at the 6-mm zone and also the various other at the 7-mm zone.
Scientific studies have revealed laser thermokeratoplasty (LTK) to be an effective approach of fixing a patient’s hyperopia, and it might additionally hold promise for treating presbyopia and overcorrected myopia after LASIK or PRK, stated David J. Conway, OD, supervisor of refractive surgery for Harvard Lead Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK technique as well as its outcomes with hyperopia utilizing the Hyperion laser (Sunrise Technologies International, Fremont, Calif.) at the International Society of Refractive Surgical procedure’s Summertime World Refractive Surgical Treatment Symposium 2000. Dr. Conway was not associated with any type of Fda (FDA) study; his ISRS discussion was based on info from the Sunrise FDA examinations and talks he attended.
When treating a patient for hyperopia, the specialist requires to stress the impermanence of the treatment, he said. “You require to convey to the patient that this is just a temporary change in his or her hyperopic standing,” he claimed. “There is enough regression with this technique that the FDA felt it needed to make mention of this.”
Any treatment for the modification of hyperopia might demand retreatment with time; this is not unique to LTK, claimed Sandra Belmont, MD, supervisor of the laser vision center at the Cornell Weill Medical Center in New York City City. “Hyperopia enhances as you age,” she claimed. “We have individuals 3 years out who are steady, so I’m extremely delighted with the outcomes.”
Dr. Belmont informs patients of this possibility, however none have actually changed their minds. She said that if retreatment were required, individuals did incline since the treatment fasts, and also creating a flap, which can lead to complications, is not required.
The LTK procedure
picture– Stability: One researcher has people who are still secure 3 years post-LTK.
The procedure, Dr. Conway said, takes 3 secs to perform. 7 pulses are applied in eight areas, twice consecutively, one at the 6-mm area and also the various other at the 7-mm area. The FDA research study reported that the 612 eyes in 379 clients, all older than 40, ranging from +0.75 to +2.50 D, saw no loss in best spectacle-corrected visual acuity (BSCVA) after 2 years, he kept in mind.
” No loss of lines of skill were attributable to the LTK,” he stated. “In contrasting preop to 24 months later on, there was no loss of BSCVA and also a little bit of gain. We understand that myopes and also hyperopes are very different. Fortunately, the resistance of hyperopes is really useful in making their satisfaction level very high.”
Before the treatment, people receive 3 successive administrations of topical proparacaine at 3-minute periods. Issues were very little, Dr. Conway kept in mind.
” People are typically handled from a convenience standpoint, purely with non-prescription anesthetics to get them through the initial hours of healing,” he stated. “Since you’re servicing the corneal surface area, FDA detectives reported a bit of foreign-body feeling, which dissipates with time very well.”
Regression in time
Dr. Conway said that, while the individual’s acuity degree stays fairly stable, some regression appears as the hyperopia enhances gradually. “There will certainly be a little but considerable regression in these clients; it’s simply an issue of whether it goes to a low enough degree to justify the patient’s price and experience of undertaking this technique,” he stated. “By contrasting your cycloplegic to your manifest refraction, you can inform whether it’s latent hyperopia or not.”
A patient’s age consider to the length of time the impact of LTK might last, claimed Dr. Conway. “A 50-year-old patient will certainly experience a bit more impact than a 40-year-old patient, maybe because of a little bit more dryness or the collagen status of the cornea,” he said.
An off-label indicator of LTK is the therapy of presbyopia, stated Dr. Belmont. People who are plano and presbyopic may be treated with LTK to achieve monovision, she claimed. “Immediately, their analysis vision enters focus,” she stated. “They get their results instantly, and they’re actually satisfied with that.”
Clients that have been dealt with for presbyopia commonly will come across the very same level of regression as hyperopes, Dr. Belmont noted. “Presbyopia enhances as you age, as does hyperopia,” she claimed. “People understand that this treatment will have to be enhanced as their aging necessitates an increase in the power they’ll need to check out. They enjoy as long as you tell them ahead of time. I expect this as being the treatment to deal with farsightedness and presbyopia.”
The length of time required for presbyopic therapy coincides when it comes to that of hyperopia, yet the degree of power that is applied to the eye is varied, she claimed.
The procedure might likewise verify to be a valid option for improving short-sighted clients who have actually been overcorrected with LASIK or PRK, claimed Dr. Conway. “This values a lot of consideration, since you don’t need to get rid of any tissue,” he claimed. “Additionally, Sunup is sending for approval remediation of presbyopia, making clients nearsighted in a monovision style. So, I assume this will become a rather preferred and usual option in this individual population, and also we’ll see the amount of even more surgeons determine to welcome it.”
LTK is authorized for up to +2.5 D, said Dr. Belmont, and also is presently undertaking tests for therapy approximately +5.6 D.
Refractec’s conductive keratoplasty
Initial medical trials recommend that conductive keratoplasty (CK) using Refractec’s (Irvine, Calif.) radiofrequency method is most likely secure and effective for dealing with low to modest quantities of hyperopia, according to Dime A. Asbell, MD, who provided clinical trial data in Miami at the International Culture of Refractive Surgical treatment meeting. “Very early outcomes with our data bent on one year suggest that we get wonderful visual acuity, very good security and also really no adverse occasions, such as loss of vision,” said Dr. Asbell.
CK heats up the stromal tissue with an electric existing, reduces the collagen and also steepens the main cornea, Dr. Asbell explained. A high-frequency current is used directly right into the peripheral corneal stroma via a delivery pointer inserted at 8 or even more therapy factors. The release of radiofrequency power heats up the surrounding collagen to a homogenous temperature level of 65 ° C as well as generates a round footprint 500 µm deep vs. a shallower, conical impact made with the LTK technique. A cycle of CK-treated areas cinches the cornea and also increases its curvature to reduce hyperopia.
” The modification appears to be irreversible, as well as I think among the factors that’s true is that the treatment is provided straight to the stroma,” said Dr. Asbell. “That’s where you want the effect– not on the endothelium, not on the epithelium. It’s an extremely simple surgical strategy. It’s a non-laser technique, and also it adds an additional measurement to what we already can use for refractive surgical treatment– it is an economical procedure,” she included.
CK is consistent
An additional crucial issue, Dr. Asbell pointed out, is that CK is a consistent treatment. “The therapy size as well as the area result in the stroma correspond from therapy place to treatment area,” she claimed. “One of the key issues to bear in mind is that the temperature we get with the CK procedure is constantly 65 ° as well as the imprint you make within the outer corneal stroma is constantly the exact same: 100 µm wide as well as 500 µm deep within the corneal stroma.”
Dr. Asbell is a detective in the FDA medical test of CK. Other 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 patients on whom Dr. Asbell reported, the common age was 55, although, she claimed, there is a relatively vast array of age amongst the trial’s participants. To get the trial, she clarified, individuals needed to have uncorrected visual acuity of a minimum of 20/40 or worse and also bad near vision also– standard for a hyperope. “We are correcting from 1 D to 4 D of hyperopia, with little or no astigmatism,” Dr. Asbell reported.
She stressed the rate and also simplicity of the treatment. “This treatment takes 5 mins per eye. It is a very brief procedure; you remain in as well as out extremely quickly,” she stated. “It is a procedure, yet a very simple one. It does not require a qualified service technician [to assist] It does not even call for an autoclave. The pointer, which has to do with the size of a hair, is non reusable.”
Dr. Asbell described the CK nomogram therefore: “The therapy is either at 6 mm, 7 mm or 8 mm. You make a mark on the cornea [indicating the dimension of the treatment zone] The level of hyperopia you are dealing with figures out the number of therapy marks on the cornea. Each one coincides– the exact same amount of power as well as the very same deepness within the stroma in each place,” she stated.
Results appear stable
Of the patients on whom Dr. Asbell reported, 61% achieved uncorrected visual acuity of 20/20 or much better 6 months postoperatively as well as 96% were 20/40 or much better at the 6-month mark. One year postoperatively, 62% were 20/20 or better, and also 92% were 20/40 or better. “Our outcomes look great and steady. These are really satisfied individuals,” said Dr. Asbell. “They actually can return to function instantly or absolutely the following day if they so choose. No one takes pain medications.”
Security variables were “essentially no,” Dr. Asbell reported. “There was no loss of vision as well as no corneal edema,” she said. “I believe this is mosting likely to be a treatment as well as an equipment that’s mosting likely to be simple for us to possess as well as to make use of as well as an excellent method to deal with hyperopia postop LASIK or to repair a postop cataract or corneal transplant,” she stated. “I assume it’s mosting likely to have a lot of versatility in terms of its uses for fixing hyperopia and also potentially astigmatism.”
Increased scientific trials of LAPR
SurgiLight Inc. (Orlando, Fla.) has actually broadened its medical test researches of laser presbyopia turnaround (LAPR) utilizing its IR-laser in Venezuela, Argentina, Brazil, the Bahamas and Japan. Likewise, the firm has actually set up installation of the IR-laser in some European countries.
SurgiLight has submitted 4 documents to the American Culture of Cataract as well as Refractive Surgery for the May 2001 conference, where more than 500 cases of LAPR will certainly be presented by ophthalmologists from different countries making use of the business’s IR laser.
The company remains in the process of obtaining CE-Mark certification as well as choosing various worldwide representatives. It intends to send additional 510K applications based upon certain clearances acquired from Premier Laser Solutions. SurgiLight anticipates to charge a royalty charge of $500 per person to specialists that make use of the business’s IR-3000 system in the USA as well as Europe.
B&L NuVita phakic IOL
The 3rd generation of George Baikoff, MD’s, anterior chamber phakic IOL is represented with Bausch & Lomb’s (St. Louis) NuVita MA20. The lens is offered for myopes ranging from 7 D to 20 D. The style is an angle-fixated, single-piece lens, with a meniscus optical form and a PMMA surface. The general optical diameter is 5 mm as well as the general size of the NuVita ranges from 12 mm to 13.5 mm in 0.5-mm increments.
The optic, loophole and footplate were all redesigned from the previous variation to lower refracted glow, pressure in the angle and far better clearance of the iris as well as all-natural lens. Likewise, the haptics were upgraded to remove iris retraction. The haptics were made extra flexible as well as, for that reason, led to much less student ovalization.
In its second generation, the fluorine plasma therapy was included in the manufacturing process to develop covalent bonds of fluorocarbon radicals with the PMMA surface, which generated lower surface power and also extremely smooth coating. The fluorine therapy considerably boosted biocompatibility.
In research studies carried out by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes dental implanted showed an accuracy price of ± 0.5 D while 97% showed an accuracy rate of ± 2 D. In terms of safety and security, the BSCVA prices had 47 getting a minimum of 2 lines, as well as no eyes lost lines. The general glare record revealed that many patients had few issues.
According to Mike Landreville, global supervisor for refractive technologies at Bausch & Lomb, the company has no intention of presenting the NuVita lens into the USA for FDA approval or for scientific usage. Rather, the firm is developing a whole new phakic technology for a collapsible anterior chamber phakic lens. The new phakic lens will certainly not only exist as a brand-new lens, however as part of a totally new system, completely different from the NuVita line. The brand-new, unrevealed lens system will certainly be of a new material, include a brand-new foldable delivery system and offer a brand-new diagnostic device for implantation.
According to Mr. Landreville, the company intends to have the brand-new system prepared for scientific usage in the United States by this year.
Alcon phakic IOL
A brand-new anterior 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) product and also has numerous advantages over other phakic IOLs such as its foldability, which enables the lens to be inserted with a cut smaller sized than 3 mm, along with an angle-fixated, single-piece style as well as high biocompatibility. The distance in between the cornea and the implant likewise falls between 2.96 mm and also 3.35 mm, a larger distance than with some other lenses, he said.
Dr. Maxwell reported that of the 10 implants that have actually been carried out to date, greater than 90% of the people have 20/40 or far better uncorrected vision at their postoperative brows through. The mean round matching in people dental implanted thus far was– 11.5 D, he stated, with an outcome of– 0.39 D at 1 month as well as– 0.8 D at 6 months of residual myopia.
” We see significant enhancement in best-corrected visual acuity, and in all but one individual the postoperative ideal remedied vision is better than the most effective preoperative vision; in a lot of 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 revealed at the AAO meeting that it has obtained three patents from Dr. Baikoff for foldable phakic anterior chamber IOL makes to deal with not just nearsightedness and also hyperopia yet additionally presbyopia.
” We are very delighted regarding this new technology,” David Bailey, surgical service unit president for CIBA, stated. “We assume that the MemoryLens product incorporated with these anterior chamber layouts will certainly be a very successful mix.”
That former chamber lens initiative enhances another refractive implant that was the topic of numerous 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 as well as now holds unique worldwide advertising and marketing and circulation rights to the lens, which is presently in phase 2 scientific trials.
” We are taking a solid setting in phakic IOLs,” Mr. Bailey stated, “and also we’ll be strengthening that placement with even more new modern technology.”
This is the method to treat nearsightedness, ypermetropia as well as astigmatism (υπερμετρωπια ).