Emerging technology in the locations of corneal ring sectors, holmium laser thermokeratoplasty (LTK) and also phakic IOLs is giving new choices for patients struggling with keratoconus, myopia, hyperopia as well as presbyopia.
Intacs for keratoconus
At the American Academy of Ophthalmology (AAO) meeting in October 2000, Joseph Colin, MD, presented a study of choices to permeating keratoplasty for individuals with keratoconus. Of 23 eyes in 20 people, 60% attained a best-corrected visual acuity of 20/40 or better. The mean postoperative keratometry was decreased by 3 D.
Daniel S. Durrie, MD, commented on Dr. Colin’s paper, which suggests a choice that strengthens the already deteriorated cornea as opposed to more thinning it with LASIK. The suggestion of using an additive procedure, such as Intacs (KeraVision, Fremont, Calif.), to strengthen the cornea makes a lot of sense, Dr. Durrie informed Medical care Optometry News.
” For many years, we have actually checked out various other choices to corneal transplants for these clients, and also some procedures such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have been tried in the past, but they eliminate part of the cornea in an individual population in which we know the cornea is already thin and also weak,” Dr. Durrie claimed.
Because the keratoconic eye has a lump in the cornea, Dr. Durrie claimed, positioning the Intacs insert in the perimeter of the cornea will certainly squash the corneal center. This not only lowers the level of myopia, but enhances the facility bulge, he stated. The wanted result is to postpone a corneal transplant for as long as feasible.
While the information that Dr. Colin offered program that the procedure is rather risk-free, claimed Dr. Durrie, the longest term data offered are only 2 years. “Checking out the trends in the 3-month, 6-month and also 1-year data, it shows up that all patients gained from the procedure, however we can not state that it stopped the keratoconus for longer than that until additional information are accumulated,” he said. “Although I continue to do this procedure on isolated cases, I tell people we don’t understand the lasting results as well as we do not know whether it will certainly reduce, quicken or have no result on the normal course of keratoconus.
” The benefit of this treatment is, if it does not work, you can take the Intacs out as well as have actually not deteriorated the cornea,” he proceeded. “If the person does need to go on to a corneal transplant, the inserts can be gotten as well as not interfere with standard transplant therapy. As a result of the modification in shape of the keratoconic cornea, ultimately, patients end up being get in touch with lens intolerant, and also it is very important to recognize that there is an alternative to be explored for these clients besides just referring them for a corneal transplant.”
Practitioners need to be sure that patients comprehend that the treatment is not refractive surgical procedure and also will not necessarily remedy their nearsightedness, said Dr. Durrie. “I have individuals on whom I have actually executed this procedure who have seen 20/40 without glasses, which would be an impressive result after a corneal transplant, but they’re still wondering why their close friends that have actually had Intacs implanted can see 20/20 when they can’t,” he said. “That’s why these patients require to be educated that this isn’t something that maintains them from using glasses. It keeps them from requiring a corneal transplant.”
Hyperopic change with LTK
photo– Post-LTK: The pulses are applied in 8 areas, one at the 6-mm area and also the various other at the 7-mm area.
Scientific studies have actually shown laser thermokeratoplasty (LTK) to be an effective approach of remedying a person’s hyperopia, and also it might also hold assurance for treating presbyopia as well as overcorrected myopia after LASIK or PRK, claimed David J. Conway, OD, manager of refractive surgical treatment for Harvard Lead Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK technique as well as its results with hyperopia utilizing the Hyperion laser (Sunup Technologies International, Fremont, Calif.) at the International Society of Refractive Surgery’s Summertime World Refractive Surgical Treatment Seminar 2000. Dr. Conway was not involved in any kind of Food and Drug Administration (FDA) study; his ISRS discussion was based upon info from the Daybreak FDA examinations and also talks he went to.
When dealing with a patient for hyperopia, the specialist needs to emphasize the brevity of the procedure, he claimed. “You need to share to the patient that this is just a short-lived adjustment in his/her hyperopic status,” he claimed. “There is enough regression with this technique that the FDA felt it required to make mention of this.”
Any type of procedure for the correction of hyperopia may demand retreatment over time; this is not distinct to LTK, claimed Sandra Belmont, MD, director of the laser vision center at the Cornell Weill Medical Center in New York City City. “Hyperopia increases as you age,” she claimed. “We have clients 3 years out who are secure, so I’m really satisfied with the outcomes.”
Dr. Belmont educates people of this possibility, but none of them have changed their minds. She said that if retreatment were required, patients did not mind because the procedure fasts, and producing a flap, which can cause issues, is not essential.
The LTK treatment
photograph– Security: One scientist has people that are still stable 3 years post-LTK.
The procedure, Dr. Conway claimed, takes 3 secs to carry out. 7 pulses are used in 8 areas, two times consecutively, one at the 6-mm area and the other at the 7-mm area. The FDA research study reported that the 612 eyes in 379 clients, 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 skill were attributable to the LTK,” he claimed. “In comparing preop to 24 months later, there was no loss of BSCVA and also a bit of gain. We understand that myopes and also hyperopes are really various. The good news is, the resistance of hyperopes is really useful in making their contentment degree very high.”
Prior to the procedure, people obtain 3 successive administrations of topical proparacaine at 3-minute intervals. Problems were minimal, Dr. Conway noted.
” Patients are generally taken care of from a comfort standpoint, strictly with over the counter anesthetics to obtain them through the very first hrs of recuperation,” he claimed. “Because you’re working on the corneal surface, FDA detectives reported a little bit of foreign-body experience, which dissipates with time very perfectly.”
Regression over time
Dr. Conway claimed that, while the individual’s acuity degree stays fairly secure, some regression appears as the hyperopia increases with time. “There will certainly be a little but considerable regression in these people; it’s simply a matter of whether it goes to a low adequate level to validate the client’s price and experience of undergoing this method,” he said. “By comparing your cycloplegic to your show refraction, you can tell whether it’s latent hyperopia or otherwise.”
A person’s age factors in to for how long the impact of LTK might last, stated Dr. Conway. “A 50-year-old individual will certainly experience a little much more result than a 40-year-old client, probably because of a little bit much more dry skin or the collagen status of the cornea,” he said.
An off-label indication of LTK is the therapy of presbyopia, said Dr. Belmont. People that are plano and also presbyopic might be treated with LTK to attain monovision, she claimed. “As soon as possible, their reading vision enters into focus,” she said. “They obtain their results instantly, as well as they’re really delighted keeping that.”
People who have been treated for presbyopia typically will come across the very same level of regression as hyperopes, Dr. Belmont kept in mind. “Presbyopia increases as you age, as does hyperopia,” she claimed. “Clients recognize that this procedure will certainly have to be boosted as their aging necessitates an increase in the power they’ll need to review. They more than happy as long as you tell them beforehand. I anticipate this as being the treatment to deal with farsightedness as well as presbyopia.”
The length of time needed for presbyopic therapy coincides as for that of hyperopia, but the level of energy that is related to the eye is varied, she said.
The procedure may likewise prove to be a legitimate choice for enhancing short-sighted individuals who have actually been overcorrected with LASIK or PRK, claimed Dr. Conway. “This qualities a lot of consideration, since you don’t need to remove any type of cells,” he said. “Furthermore, Daybreak is sending for authorization remediation of presbyopia, making patients short-sighted in a monovision fashion. So, I believe this will become a rather popular as well as usual option in this patient populace, as well as we’ll see how many even more doctors determine to welcome it.”
LTK is approved for as much as +2.5 D, claimed Dr. Belmont, and also is currently undertaking tests for therapy up to +5.6 D.
Refractec’s conductive keratoplasty
Initial scientific tests suggest that conductive keratoplasty (CK) using Refractec’s (Irvine, Calif.) radiofrequency approach is possibly secure and also reliable for fixing low to moderate amounts of hyperopia, according to Penny A. Asbell, MD, that offered scientific test information in Miami at the International Culture of Refractive Surgery meeting. “Early outcomes with our information bent on 12 months suggest that we obtain wonderful visual acuity, excellent security as well as really no unfavorable events, such as loss of vision,” claimed Dr. Asbell.
CK warms the stromal cells with an electrical present, shrinks the collagen and steepens the main cornea, Dr. Asbell discussed. A high-frequency current is used straight into the outer corneal stroma through a shipment pointer placed at 8 or even more treatment points. The release of radiofrequency energy heats up the surrounding collagen to an uniform temperature level of 65 ° C and also generates a cylindrical footprint 500 µm deep vs. a shallower, conelike footprint made with the LTK technique. A cycle of CK-treated areas cinches the cornea and also enhances its curvature to lower hyperopia.
” The change seems to be irreversible, as well as I believe one of the reasons that’s true is that the therapy is supplied directly to the stroma,” stated Dr. Asbell. “That’s where you desire the effect– not on the endothelium, not on the epithelium. It’s a very simple medical technique. It’s a non-laser strategy, and also it adds one more measurement to what we already can provide for refractive surgical treatment– it is an affordable treatment,” she included.
CK is consistent
Another vital problem, Dr. Asbell pointed out, is that CK is a regular treatment. “The treatment size and the zone effect in the stroma are consistent from therapy place to therapy place,” she said. “One of the crucial issues to remember is that the temperature we get with the CK treatment is always 65 ° and the imprint you make within the peripheral corneal stroma is constantly the same: 100 µm wide as well as 500 µm deep within the corneal stroma.”
Dr. Asbell is an investigator in the FDA clinical trial of CK. Fellow private investigators at other sites consist of Marguerite McDonald, MD; Robert K. Maloney, MD; Jonathan Davidorf, MD; Peter Hersh, MD; and also Edward E. Manche, MD
. Of the 54 patients on whom Dr. Asbell reported, the common age was 55, although, she claimed, there is a rather large range old among the trial’s individuals. To qualify for the trial, she explained, patients needed to have uncorrected visual acuity of a minimum of 20/40 or even worse as well as poor near vision also– standard for a hyperope. “We are dealing with from 1 D to 4 D of hyperopia, with little or no astigmatism,” Dr. Asbell reported.
She worried the speed as well as simpleness of the treatment. “This treatment takes 5 minutes per eye. It is an extremely brief treatment; you’re in and also out very quickly,” she said. “It is a procedure, yet a really straightforward one. It does not need a trained service technician [to assist] It does not also require an autoclave. The suggestion, which has to do with the size of a hair, is non reusable.”
Dr. Asbell described the CK nomogram thus: “The therapy is either at 6 mm, 7 mm or 8 mm. You make a mark on the cornea [suggesting the dimension of the therapy area] The degree of hyperopia you are correcting figures out the variety of treatment marks on the cornea. Each one coincides– the same amount of power and also the same depth within the stroma in each place,” she claimed.
Results appear steady
Of the clients on whom Dr. Asbell reported, 61% accomplished uncorrected visual acuity of 20/20 or better 6 months postoperatively and also 96% were 20/40 or far better at the 6-month mark. One year postoperatively, 62% were 20/20 or far better, and 92% were 20/40 or far better. “Our results look good and secure. These are really happy patients,” stated Dr. Asbell. “They really can return to work instantly or certainly the following day if they so pick. No one takes discomfort medicines.”
Security variables were “generally no,” Dr. Asbell reported. “There was no loss of vision as well as no corneal edema,” she said. “I believe this is going to be a treatment as well as a maker that’s mosting likely to be simple for us to own as well as to use and an outstanding method to remedy hyperopia postop LASIK or to touch up a postop cataract or corneal transplant,” she said. “I believe it’s going to have a great deal of flexibility in terms of its uses for dealing with hyperopia and also potentially astigmatism.”
Increased clinical trials of LAPR
SurgiLight Inc. (Orlando, Fla.) has increased its scientific trial studies of laser presbyopia turnaround (LAPR) utilizing its IR-laser in Venezuela, Argentina, Brazil, the Bahamas as well as Japan. Likewise, the firm has actually arranged installation of the IR-laser in some European nations.
SurgiLight has actually sent 4 documents to the American Society of Cataract as well as Refractive Surgical Procedure for the May 2001 conference, where greater than 500 situations of LAPR will exist by eye doctors from different nations making use of the business’s IR laser.
The business remains in the process of acquiring CE-Mark qualification and also picking different worldwide distributors. It prepares to submit additional 510K applications based upon particular clearances gotten from Premier Laser Solutions. SurgiLight expects to bill an aristocracy fee of $500 per patient to cosmetic surgeons 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 represented with Bausch & Lomb’s (St. Louis) NuVita MA20. The lens is readily available for myopes ranging from 7 D to 20 D. The style is an angle-fixated, single-piece lens, with a crescent optical form and also a PMMA surface. The total optical size is 5 mm and the total length of the NuVita varies from 12 mm to 13.5 mm in 0.5-mm increments.
The optic, loop and footplate were all revamped from the previous variation to lower refracted glare, stress in the angle and far better clearance of the iris as well as natural lens. Also, the haptics were revamped to eliminate iris retraction. The haptics were made much more adaptable and also, therefore, caused less pupil ovalization.
In its 2nd generation, the fluorine plasma therapy was contributed to the manufacturing process to produce covalent bonds of fluorocarbon radicals with the PMMA surface area, which generated lower surface area energy and extremely smooth coating. The fluorine treatment considerably enhanced biocompatibility.
In researches performed by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes implanted revealed an accuracy price of ± 0.5 D while 97% showed an accuracy price of ± 2 D. In regards to safety and security, the BSCVA rates had 47 getting a minimum of 2 lines, and no eyes shed lines. The total glow record revealed that the majority of people had few problems.
According to Mike Landreville, global director for refractive technologies at Bausch & Lomb, the business has no purpose of introducing the NuVita lens right into the United States for FDA authorization or for medical use. Instead, the firm is developing an entire new phakic modern technology for a collapsible anterior chamber phakic lens. The new phakic lens will not just exist as a new lens, but as part of a completely new system, totally different from the NuVita line. The new, unrevealed lens system will be of a brand-new material, incorporate a new foldable distribution system and provide a new analysis device for implantation.
According to Mr. Landreville, the company plans to have the new system all set for scientific usage in the USA by this year.
Alcon phakic IOL
A new former chamber phakic IOL existed by Andrew Maxwell, MD, PhD, at the AAO meeting. The lens has an Acrysof-based (Alcon, Ft. Worth, Texas) product as well as has a number of advantages over various other phakic IOLs such as its foldability, which enables the lens to be put via an incision smaller than 3 mm, in addition to an angle-fixated, single-piece layout and high biocompatibility. The distance in between the cornea and also the implant additionally drops in between 2.96 mm and also 3.35 mm, a bigger range than with some other lenses, he said.
Dr. Maxwell reported that of the 10 implants that have actually been executed to date, more than 90% of the patients have 20/40 or better uncorrected vision at their postoperative check outs. The mean spherical matching in people dental implanted thus far was– 11.5 D, he said, with an outcome of– 0.39 D at 1 month as well as– 0.8 D at 6 months of recurring myopia.
” We see substantial enhancement in best-corrected visual acuity, as well as in all but one client the postoperative ideal fixed vision is better than the most effective preoperative vision; oftentimes, there are 2-, 3- or 4-line rises in best-corrected visual acuity,” Dr. Maxwell stated. “In the one situation where it had not been better, it coincided as the preoperative acuity.”
CIBA obtains licenses for IOL
CIBA Vision introduced at the AAO conference that it has actually gotten 3 patents from Dr. Baikoff for foldable phakic former chamber IOL develops to correct not just myopia as well as hyperopia but also presbyopia.
” We are really thrilled regarding this new technology,” David Bailey, surgical company system president for CIBA, stated. “We believe that the MemoryLens product combined with these anterior chamber designs will certainly be a very successful mix.”
That anterior chamber lens effort enhances one more refractive dental implant that was the topic of several presentations in the CIBA Vision cubicle– 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 also currently holds special around the world advertising and distribution rights to the lens, which is currently in phase 2 clinical trials.
” We are taking a strong position in phakic IOLs,” Mr. Bailey said, “and we’ll be strengthening that position with more new technology.”
This is the way to treat myopia, ypermetropia and astigmatism (μυωπια ).