Emerging technology in the locations of corneal ring sections, holmium laser thermokeratoplasty (LTK) and also phakic IOLs is offering new alternatives for clients experiencing keratoconus, nearsightedness, hyperopia and also presbyopia.
Intacs for keratoconus
At the American Academy of Ophthalmology (AAO) conference in October 2000, Joseph Colin, MD, provided a study of alternatives to penetrating keratoplasty for individuals with keratoconus. Of 23 eyes in 20 individuals, 60% achieved a best-corrected visual acuity of 20/40 or much better. The mean postoperative keratometry was decreased by 3 D.
Daniel S. Durrie, MD, commented on Dr. Colin’s paper, which recommends an option that reinforces the already damaged 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 feeling, Dr. Durrie informed Primary Care Optometry News.
” For years, we’ve checked out various other alternatives to corneal transplants for these people, as well as some procedures such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have actually been tried in the past, but they eliminate part of the cornea in a person population in which we know the cornea is already thin and weak,” Dr. Durrie said.
Since the keratoconic eye has a lump in the cornea, Dr. Durrie claimed, putting the Intacs insert in the periphery of the cornea will certainly flatten the corneal center. This not just lowers the degree of nearsightedness, however reinforces the center bulge, he stated. The desired end result is to delay a corneal transplant for as long as feasible.
While the information that Dr. Colin offered show that the treatment is rather risk-free, claimed Dr. Durrie, the lengthiest term information available are only 2 years. “Taking a look at the trends in the 3-month, 6-month and 1-year data, it shows up that all people gained from the treatment, but we can not state that it stopped the keratoconus for longer than that until more data are accumulated,” he said. “Although I remain to do this procedure on isolated situations, I inform clients we do not understand the long-lasting effects and also we do not understand whether it will decrease, quicken or have no effect on the normal course of keratoconus.
” The advantage of this treatment is, if it doesn’t work, you can take the Intacs out and have not damaged the cornea,” he continued. “If the patient does require to go on to a corneal transplant, the inserts can be secured as well as not interfere with basic transplant therapy. Because of the adjustment fit of the keratoconic cornea, ultimately, clients become get in touch with lens intolerant, and also it’s important to recognize that there is a different to be examined for these patients apart from simply referring them for a corneal transplant.”
Professionals ought to be sure that individuals comprehend that the procedure is not refractive surgical treatment and will certainly not always correct their nearsightedness, said Dr. Durrie. “I have individuals on whom I have actually done this procedure who have seen 20/40 without glasses, which would certainly be an exceptional result after a corneal transplant, yet they’re still asking yourself why their buddies that have had Intacs implanted can see 20/20 when they can’t,” he said. “That’s why these patients need to be informed that this isn’t something that maintains them from putting on glasses. It keeps them from requiring a corneal transplant.”
Hyperopic adjustment with LTK
picture– Post-LTK: The pulses are used in eight places, one at the 6-mm area and also the other at the 7-mm zone.
Professional researches have shown laser thermokeratoplasty (LTK) to be a reliable approach of correcting a person’s hyperopia, and also it may additionally hold assurance for treating presbyopia and overcorrected nearsightedness after LASIK or PRK, claimed David J. Conway, OD, supervisor of refractive surgical treatment for Harvard Lead Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK strategy as well as its results with hyperopia utilizing the Hyperion laser (Dawn Technologies International, Fremont, Calif.) at the International Culture of Refractive Surgery’s Summertime Globe Refractive Surgery Seminar 2000. Dr. Conway was not involved in any type of Food and Drug Administration (FDA) study; his ISRS discussion was based upon info from the Sunup FDA investigations and talks he participated in.
When dealing with a patient for hyperopia, the professional requires to emphasize the brevity of the procedure, he stated. “You need to communicate to the client that this is just a short-term adjustment in his/her hyperopic condition,” he stated. “There suffices regression with this technique that the FDA felt it needed to make mention of this.”
Any kind of procedure for the adjustment of hyperopia may necessitate retreatment gradually; this is not special to LTK, stated Sandra Belmont, MD, supervisor of the laser vision facility at the Cornell Weill Medical Facility in New York City City. “Hyperopia raises as you age,” she stated. “We have patients 3 years out that are steady, so I’m extremely happy with the results.”
Dr. Belmont educates patients of this opportunity, however none have actually changed their minds. She said that if retreatment were needed, individuals did incline due to the fact that the treatment fasts, and also developing a flap, which can lead to complications, is not essential.
The LTK procedure
photograph– Stability: One researcher has people that are still secure 3 years post-LTK.
The treatment, Dr. Conway claimed, takes 3 seconds to execute. 7 pulses are applied in 8 spots, twice back to back, one at the 6-mm zone and also the various other at the 7-mm zone. The FDA research reported that the 612 eyes in 379 individuals, all older than 40, varying 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 acuity were attributable to the LTK,” he claimed. “In contrasting preop to 24 months later, there was no loss of BSCVA and also a little bit of gain. We know that myopes and also hyperopes are extremely various. Fortunately, the tolerance of hyperopes is really valuable in making their contentment degree really high.”
Before the procedure, people get three consecutive managements of topical proparacaine at 3-minute intervals. Issues were very little, Dr. Conway kept in mind.
” Patients are typically taken care of from a convenience perspective, strictly with non-prescription analgesics to get them through the first hours of healing,” he said. “Due to the fact that you’re working on the corneal surface, FDA investigators reported a bit of foreign-body sensation, which dissipates with time extremely well.”
Dr. Conway stated that, while the client’s skill level remains fairly steady, some regression is evident as the hyperopia raises in time. “There will certainly be a tiny yet substantial regression in these people; it’s simply a matter of whether it’s at a low adequate level to validate the individual’s price and experience of undergoing this strategy,” he stated. “By contrasting your cycloplegic to your show refraction, you can inform whether it exists hyperopia or not.”
A patient’s age factors in to for how long the result of LTK may last, claimed Dr. Conway. “A 50-year-old patient will experience a little bit a lot more impact than a 40-year-old patient, possibly because of a little a lot more dryness or the collagen status of the cornea,” he said.
An off-label sign of LTK is the treatment of presbyopia, stated Dr. Belmont. Clients that are plano and presbyopic may be treated with LTK to accomplish monovision, she claimed. “Right now, their analysis vision enters emphasis,” she claimed. “They obtain their results immediately, and also they’re truly pleased with that said.”
People that have actually been treated for presbyopia generally will run into the exact same level of regression as hyperopes, Dr. Belmont kept in mind. “Presbyopia enhances as you age, as does hyperopia,” she said. “Patients know that this treatment will certainly have to be enhanced as their aging requires a rise in the power they’ll need to review. They more than happy as long as you tell them ahead of time. I anticipate this as being the procedure to treat farsightedness and also presbyopia.”
The size of time needed for presbyopic therapy is the same when it comes to that of hyperopia, yet the level of power that is applied to the eye is varied, she claimed.
The procedure might likewise show to be a legitimate option for improving myopic patients who have been overcorrected with LASIK or PRK, claimed Dr. Conway. “This values a great deal of consideration, because you do not have to get rid of any type of cells,” he said. “In addition, Daybreak is submitting for approval remediation of presbyopia, making individuals myopic in a monovision style. So, I assume this will certainly end up being a fairly preferred as well as typical option in this patient population, and also we’ll see how many more specialists decide to embrace it.”
LTK is accepted for approximately +2.5 D, stated Dr. Belmont, and is presently undertaking trials for therapy as much as +5.6 D.
Refractec’s conductive keratoplasty
Preliminary medical trials suggest that conductive keratoplasty (CK) utilizing Refractec’s (Irvine, Calif.) radiofrequency approach is most likely secure and also efficient for remedying low to moderate amounts of hyperopia, according to Cent A. Asbell, MD, who provided scientific trial data in Miami at the International Culture of Refractive Surgery meeting. “Early results with our data out to year recommend that we get terrific visual acuity, excellent security and also really no damaging events, such as loss of vision,” claimed Dr. Asbell.
CK heats the stromal cells with an electric present, diminishes the collagen and also steepens the central cornea, Dr. Asbell described. A high-frequency current is used straight into the outer corneal stroma through a distribution idea placed at eight or more treatment points. The launch of radiofrequency power heats the surrounding collagen to an identical temperature level of 65 ° C as well as produces a round impact 500 µm deep vs. a shallower, conical footprint made with the LTK method. A cycle of CK-treated places cinches the cornea as well as raises its curvature to decrease hyperopia.
” The modification seems to be long-term, and I assume among the factors that’s true is that the therapy is delivered straight to the stroma,” claimed Dr. Asbell. “That’s where you want the impact– not on the endothelium, out the epithelium. It’s a really easy surgical strategy. It’s a non-laser technique, and it includes another dimension to what we already can provide for refractive surgical treatment– it is an affordable procedure,” she included.
CK is consistent
Another crucial issue, Dr. Asbell mentioned, is that CK is a regular treatment. “The therapy size and also the area impact in the stroma correspond from treatment area to therapy area,” she stated. “Among the vital concerns to remember is that the temperature level we get with the CK procedure is constantly 65 ° and also the imprint you make within the outer corneal stroma is constantly the very same: 100 µm vast and 500 µm deep within the corneal stroma.”
Dr. Asbell is a private investigator in the FDA medical trial of CK. Other private investigators at other sites consist of Marguerite McDonald, MD; Robert K. Maloney, MD; Jonathan Davidorf, MD; Peter Hersh, MD; as well as Edward E. Manche, MD
. Of the 54 people on whom Dr. Asbell reported, the common age was 55, although, she stated, there is a relatively large range old among the trial’s participants. To get approved for the trial, she described, patients needed to have uncorrected visual acuity of at the very least 20/40 or worse and also inadequate near vision too– basic for a hyperope. “We are remedying from 1 D to 4 D of hyperopia, with little or no astigmatism,” Dr. Asbell reported.
She emphasized the rate and also simpleness of the procedure. “This treatment takes 5 minutes per eye. It is a really brief procedure; you’re in as well as out extremely quickly,” she claimed. “It is a surgical procedure, yet a very straightforward one. It does not call for an experienced technician [to assist] It doesn’t even need an autoclave. The pointer, which has to do with the size of a hair, is non reusable.”
Dr. Asbell defined the CK nomogram thus: “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 remedying identifies the number of therapy marks on the cornea. Every one is the same– the same quantity of energy as well as the very same depth within the stroma in each spot,” she stated.
Outcomes show up steady
Of the people on whom Dr. Asbell reported, 61% attained uncorrected visual acuity of 20/20 or far better 6 months postoperatively and 96% were 20/40 or better at the 6-month mark. One year postoperatively, 62% were 20/20 or far better, and also 92% were 20/40 or much better. “Our outcomes look good as well as steady. These are very pleased clients,” claimed Dr. Asbell. “They in fact can return to work immediately or absolutely the next day if they so choose. Nobody takes discomfort medicines.”
Safety variables were “generally no,” Dr. Asbell reported. “There was no loss of vision and also no corneal edema,” she said. “I think this is mosting likely to be a procedure as well as an equipment that’s going to be simple for us to have and also to make use of and a superb means to deal with hyperopia postop LASIK or to touch up a postop cataract or corneal transplant,” she stated. “I assume it’s going to have a great deal of adaptability in regards to its usages for remedying hyperopia as well as perhaps astigmatism.”
Expanded professional trials of LAPR
SurgiLight Inc. (Orlando, Fla.) has increased its professional trial research studies of laser presbyopia turnaround (LAPR) utilizing its IR-laser in Venezuela, Argentina, Brazil, the Bahamas and also Japan. Likewise, the company has set up installation of the IR-laser in some European countries.
SurgiLight has actually sent 4 documents to the American Society of Cataract and Refractive Surgical Procedure for the May 2001 conference, where more than 500 instances of LAPR will exist by eye doctors from numerous nations using the firm’s IR laser.
The firm is in the process of getting CE-Mark accreditation as well as choosing different worldwide representatives. It intends to send added 510K applications based on specific clearances obtained from Premier Laser Solutions. SurgiLight expects to bill a nobility charge of $500 per client to doctors who make use of the firm’s IR-3000 system in the United States as well as Europe.
B&L NuVita phakic IOL
The 3rd 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 ranging from 7 D to 20 D. The style is an angle-fixated, single-piece lens, with a crescent optical shape and also a PMMA surface. The overall optical diameter is 5 mm as well as the general length of the NuVita ranges from 12 mm to 13.5 mm in 0.5-mm increments.
The optic, loophole and also footplate were all upgraded from the previous version to minimize refracted glare, pressure in the angle and also far better clearance of the iris and also natural lens. Likewise, the haptics were redesigned to get rid of iris retraction. The haptics were made more versatile and also, therefore, resulted in less student ovalization.
In its 2nd generation, the fluorine plasma treatment was included in the manufacturing procedure to develop covalent bonds of fluorocarbon radicals with the PMMA surface, which yielded lower surface area energy and also remarkably smooth finish. The fluorine treatment greatly boosted biocompatibility.
In studies carried out by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes dental implanted revealed an accuracy price of ± 0.5 D while 97% revealed a precision rate of ± 2 D. In terms of safety, the BSCVA rates had 47 getting at least 2 lines, and also no eyes lost lines. The general glare report showed that many patients had couple of problems.
According to Mike Landreville, worldwide supervisor for refractive modern technologies at Bausch & Lomb, the company has no intention of introducing the NuVita lens right into the United States for FDA approval or for professional use. Instead, the business is establishing an entire brand-new phakic modern technology for a foldable anterior chamber phakic lens. The brand-new phakic lens will not just exist as a brand-new lens, however as part of a totally new system, totally different from the NuVita line. The brand-new, unrevealed lens system will be of a new product, integrate a new collapsible delivery system as well as give a new diagnostic tool for implantation.
According to Mr. Landreville, the firm prepares to have the new system prepared for professional use in the USA by this year.
Alcon phakic IOL
A new anterior chamber phakic IOL was presented by Andrew Maxwell, MD, PhD, at the AAO meeting. The lens has an Acrysof-based (Alcon, Ft. Worth, Texas) product and also has numerous advantages over other phakic IOLs such as its foldability, which allows the lens to be put with a laceration smaller sized than 3 mm, along with an angle-fixated, single-piece layout and also high biocompatibility. The range between the cornea and the dental implant additionally drops between 2.96 mm and 3.35 mm, a larger range than with a few other lenses, he said.
Dr. Maxwell reported that of the 10 implants that have been done to day, more than 90% of the individuals have 20/40 or much better uncorrected vision at their postoperative brows through. The mean round matching in individuals dental implanted thus far was– 11.5 D, he stated, with an outcome of– 0.39 D at 1 month and also– 0.8 D at 6 months of residual myopia.
” We see considerable improvement in best-corrected visual acuity, as well as in all however one person the postoperative best fixed vision is far better than the most effective preoperative vision; oftentimes, there are 2-, 3- or 4-line increases in best-corrected visual acuity,” Dr. Maxwell said. “In the one case where it wasn’t better, it was the same as the preoperative skill.”
CIBA obtains licenses for IOL
CIBA Vision revealed at the AAO meeting that it has actually obtained 3 licenses from Dr. Baikoff for foldable phakic former chamber IOL designs to deal with not just nearsightedness as well as hyperopia yet likewise presbyopia.
” We are extremely excited regarding this brand-new technology,” David Bailey, medical company unit head of state for CIBA, claimed. “We think that the MemoryLens product integrated with these former chamber designs will be a very successful combination.”
That former chamber lens campaign matches another refractive implant that was the topic of numerous discussions in the CIBA Vision cubicle– the PRL. This posterior-chamber phakic implant is being created by Medennium Inc. CIBA Vision took a 10% equity stake in Medennium in July and currently holds unique around the world advertising and marketing and also circulation rights to the lens, which is presently in stage 2 clinical tests.
” We are taking a strong placement in phakic IOLs,” Mr. Bailey claimed, “and we’ll be enhancing that setting with even more new technology.”
This is the method to deal with myopia, ypermetropia and also astigmatism (υπερμετρωπια ).