Emerging technology in the areas of corneal ring sectors, holmium laser thermokeratoplasty (LTK) and phakic IOLs is providing new alternatives for individuals dealing with keratoconus, myopia, hyperopia and presbyopia.
Intacs for keratoconus
At the American Academy of Ophthalmology (AAO) meeting in October 2000, Joseph Colin, MD, offered a study of alternatives to passing through keratoplasty for clients 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, talked about Dr. Colin’s paper, which recommends an option that reinforces the currently compromised cornea instead of further thinning it with LASIK. The idea of using an additive procedure, such as Intacs (KeraVision, Fremont, Calif.), to enhance the cornea makes a great deal of feeling, Dr. Durrie informed Medical care Optometry Information.
” For many years, we’ve looked at various other alternatives 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, but they eliminate part of the cornea in a client population in which we know the cornea is already slim and weak,” Dr. Durrie said.
Since the keratoconic eye has a bulge in the cornea, Dr. Durrie said, positioning the Intacs insert in the perimeter of the cornea will squash the corneal facility. This not only reduces the degree of myopia, however enhances the facility lump, he said. The desired outcome is to postpone a corneal transplant for as long as feasible.
While the information that Dr. Colin offered show that the treatment is rather safe, said Dr. Durrie, the lengthiest term data readily available are just 2 years. “Considering the patterns in the 3-month, 6-month as well as 1-year data, it appears that all patients benefited from the treatment, yet we can’t say that it stopped the keratoconus for longer than that till more information are accumulated,” he said. “Although I remain to do this treatment on separated situations, I inform clients we don’t recognize the long-lasting impacts as well as we don’t recognize whether it will certainly slow down, speed up or have no result on the normal course of keratoconus.
” The benefit 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 client does need to take place to a corneal transplant, the inserts can be obtained and also not interfere with conventional transplant treatment. Because of the modification fit of the keratoconic cornea, ultimately, clients end up being call lens intolerant, and it is essential to understand that there is an alternate to be examined for these people besides simply referring them for a corneal transplant.”
Practitioners ought to make sure that individuals recognize that the procedure is not refractive surgery as well as will not necessarily correct their nearsightedness, stated Dr. Durrie. “I have clients on whom I have actually done this procedure that have actually seen 20/40 without glasses, which would certainly be a superior outcome after a corneal transplant, yet they’re still questioning why their close friends that have had Intacs implanted can see 20/20 when they can’t,” he claimed. “That’s why these patients require to be enlightened that this isn’t something that maintains them from using glasses. It keeps them from needing a corneal transplant.”
Hyperopic modification with LTK
photo– Post-LTK: The pulses are used in 8 places, one at the 6-mm area as well as the other at the 7-mm area.
Medical research studies have actually shown laser thermokeratoplasty (LTK) to be a reliable technique of fixing a patient’s hyperopia, and it may additionally hold assurance for treating presbyopia and also overcorrected nearsightedness after LASIK or PRK, said David J. Conway, OD, manager of refractive surgery for Harvard Vanguard Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK method and its results with hyperopia making use of 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 Fda (FDA) research study; his ISRS discussion was based on details from the Daybreak FDA investigations and also lectures he participated in.
When treating a patient for hyperopia, the professional requires to emphasize the brevity of the treatment, he claimed. “You need to communicate to the individual that this is just a temporary change in his/her hyperopic standing,” he stated. “There suffices regression with this method that the FDA felt it necessary to refer this.”
Any type of treatment for the improvement of hyperopia may require retreatment over time; this is not distinct to LTK, claimed Sandra Belmont, MD, director of the laser vision facility at the Cornell Weill Medical Center in New York City City. “Hyperopia raises as you age,” she said. “We have clients 3 years out that are steady, so I’m extremely happy with the results.”
Dr. Belmont informs patients of this possibility, however none have actually altered their minds. She stated that if retreatment were needed, individuals did not mind since the treatment is quick, and also developing a flap, which can lead to issues, is not necessary.
The LTK treatment
photograph– Stability: One researcher has clients that are still stable 3 years post-LTK.
The treatment, Dr. Conway stated, takes 3 secs to do. 7 pulses are applied in eight spots, twice consecutively, one at the 6-mm zone as well as the other at the 7-mm zone. The FDA research reported that the 612 eyes in 379 patients, 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 noted.
” No loss of lines of skill were attributable to the LTK,” he claimed. “In contrasting preop to 24 months later on, there was no loss of BSCVA and a little bit of gain. We know that myopes as well as hyperopes are really various. Luckily, the resistance of hyperopes is really practical in making their fulfillment level really high.”
Before the treatment, clients receive 3 consecutive administrations of topical proparacaine at 3-minute periods. Problems were minimal, Dr. Conway noted.
” People are usually handled from a comfort viewpoint, strictly with over the counter analgesics to obtain them via the very first hours of recuperation,” he claimed. “Since you’re dealing with the corneal surface area, FDA investigators reported a little bit of foreign-body feeling, which dissipates with time very perfectly.”
Regression in time
Dr. Conway stated that, while the patient’s skill level remains fairly secure, some regression is evident as the hyperopia increases gradually. “There will certainly be a tiny but substantial regression in these individuals; it’s simply an issue of whether it goes to a reduced adequate degree to validate the individual’s expense and experience of undergoing this technique,” he stated. “By contrasting your cycloplegic to your reveal refraction, you can inform whether it’s latent hyperopia or not.”
A patient’s age consider to how long the result of LTK may last, claimed Dr. Conway. “A 50-year-old patient will certainly experience a little bit much more effect than a 40-year-old client, possibly as a result of a little bit much more dryness or the collagen condition of the cornea,” he stated.
An off-label indicator of LTK is the therapy of presbyopia, claimed Dr. Belmont. Patients who are plano and also presbyopic may be treated with LTK to achieve monovision, she stated. “Today, their analysis vision enters into emphasis,” she claimed. “They obtain their results quickly, and they’re actually happy with that said.”
People that have been dealt with for presbyopia usually will experience the exact same level of regression as hyperopes, Dr. Belmont noted. “Presbyopia raises as you age, as does hyperopia,” she stated. “Individuals recognize that this treatment will need to be improved as their aging requires an increase in the power they’ll need to review. They more than happy as long as you tell them in advance. I anticipate this as being the procedure to treat farsightedness as well as presbyopia.”
The size of time needed for presbyopic treatment is the same when it comes to that of hyperopia, however the degree of energy that is related to the eye is differed, she said.
The treatment might likewise show to be a legitimate choice for enhancing short-sighted individuals who have been overcorrected with LASIK or PRK, stated Dr. Conway. “This values a lot of consideration, since you do not have to eliminate any type of cells,” he stated. “Additionally, Daybreak is submitting for authorization remediation of presbyopia, making people nearsighted in a monovision fashion. So, I think this will become a fairly preferred as well as common alternative in this client populace, and also we’ll see the number of more surgeons determine to accept it.”
LTK is approved for approximately +2.5 D, claimed Dr. Belmont, and is presently undergoing tests for therapy up to +5.6 D.
Refractec’s conductive keratoplasty
Initial clinical tests recommend that conductive keratoplasty (CK) using Refractec’s (Irvine, Calif.) radiofrequency method is most likely secure and also reliable for fixing reduced to moderate quantities of hyperopia, according to Penny A. Asbell, MD, that presented professional test data in Miami at the International Culture of Refractive Surgical procedure conference. “Very early outcomes with our data out to 12 months recommend that we get great visual acuity, excellent security and really no negative events, such as loss of vision,” claimed Dr. Asbell.
CK heats the stromal tissue with an electric existing, diminishes the collagen as well as steepens the central cornea, Dr. Asbell clarified. A high-frequency current is used straight into the peripheral corneal stroma through a distribution pointer inserted at 8 or even more therapy factors. The launch of radiofrequency power warms the surrounding collagen to a homogenous temperature of 65 ° C as well as generates a cylindrical impact 500 µm deep vs. a shallower, conelike footprint made with the LTK method. A full circle of CK-treated places cinches the cornea and also enhances its curvature to decrease hyperopia.
” The change appears to be irreversible, as well as I assume among the factors that holds true is that the treatment is supplied directly to the stroma,” said Dr. Asbell. “That’s where you want the effect– out the endothelium, not on the epithelium. It’s a very easy surgical technique. It’s a non-laser strategy, as well as it adds another measurement to what we currently can offer for refractive surgical treatment– it is an affordable treatment,” she added.
CK is consistent
One more key issue, Dr. Asbell pointed out, is that CK is a regular treatment. “The therapy dimension as well as the zone effect in the stroma are consistent from treatment place to therapy area,” she claimed. “One of the key issues to remember is that the temperature we get with the CK procedure is constantly 65 ° and the imprint you make within the outer corneal stroma is always the very same: 100 µm wide and 500 µm deep within the corneal stroma.”
Dr. Asbell is an investigator in the FDA professional test of CK. Fellow detectives 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 patients on whom Dr. Asbell reported, the regular age was 55, although, she said, there is a relatively wide variety of age among the test’s participants. To qualify for the trial, she described, people had to have uncorrected visual acuity of at least 20/40 or even worse as well as inadequate near vision as well– standard for a hyperope. “We are correcting from 1 D to 4 D of hyperopia, with little or no astigmatism,” Dr. Asbell reported.
She worried the rate as well as simpleness of the procedure. “This procedure takes 5 minutes per eye. It is a really short procedure; you remain in as well as out extremely promptly,” she claimed. “It is a surgical procedure, however a very basic one. It does not call for a skilled professional [to assist] It does not also need an autoclave. The idea, which has to do with the width of a hair, is non reusable.”
Dr. Asbell explained the CK nomogram thus: “The therapy is either at 6 mm, 7 mm or 8 mm. You make a mark on the cornea [showing the dimension of the therapy zone] The degree of hyperopia you are fixing identifies the variety of treatment marks on the cornea. Each one coincides– the very same quantity of power as well as the very same deepness within the stroma in each place,” she stated.
Results show up stable
Of the patients on whom Dr. Asbell reported, 61% attained uncorrected visual acuity of 20/20 or much better 6 months postoperatively as well as 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 better. “Our outcomes look great as well as secure. These are very pleased people,” stated Dr. Asbell. “They in fact can return to function instantly or certainly the following day if they so pick. No person takes pain medications.”
Security variables were “generally absolutely no,” Dr. Asbell reported. “There was no loss of vision and no corneal edema,” she claimed. “I think this is going to be a procedure and a machine that’s going to be simple for us to own as well as to make use of and a superb method to correct hyperopia postop LASIK or to touch up a postop cataract or corneal transplant,” she stated. “I believe it’s mosting likely to have a lot of adaptability in regards to its usages for remedying hyperopia and also potentially astigmatism.”
Increased professional tests of LAPR
SurgiLight Inc. (Orlando, Fla.) has broadened its scientific test researches of laser presbyopia turnaround (LAPR) utilizing its IR-laser in Venezuela, Argentina, Brazil, the Bahamas and also Japan. Additionally, the firm has actually arranged setup of the IR-laser in some European nations.
SurgiLight has submitted four papers to the American Society of Cataract and Refractive Surgical Procedure for the May 2001 conference, where more than 500 instances of LAPR will certainly exist by eye doctors from different nations using the company’s IR laser.
The business remains in the procedure of obtaining CE-Mark certification and also picking various worldwide distributors. It prepares to submit additional 510K applications based on particular clearances gotten from Premier Laser Equipments. SurgiLight anticipates to charge an aristocracy cost of $500 per client to cosmetic surgeons who utilize the company’s IR-3000 system in the United States and also Europe.
B&L NuVita phakic IOL
The third generation of George Baikoff, MD’s, anterior 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 layout is an angle-fixated, single-piece lens, with a meniscus optical form as well as a PMMA surface. The general optical size is 5 mm as well as the general size of the NuVita varies from 12 mm to 13.5 mm in 0.5-mm increments.
The optic, loop and also footplate were all upgraded from the previous version to decrease refracted glare, pressure in the angle and also better clearance of the iris as well as natural lens. Also, the haptics were upgraded to get rid of iris retraction. The haptics were made extra versatile as well as, therefore, caused much less pupil ovalization.
In its 2nd generation, the fluorine plasma therapy was added to the manufacturing process to produce covalent bonds of fluorocarbon radicals with the PMMA surface, which yielded lower surface energy and extremely smooth coating. The fluorine therapy substantially enhanced biocompatibility.
In researches conducted by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes implanted showed an accuracy price of ± 0.5 D while 97% revealed a precision rate of ± 2 D. In regards to safety and security, the BSCVA rates had 47 obtaining at least two lines, and also no eyes lost lines. The general glare report revealed that the majority of patients had couple of troubles.
According to Mike Landreville, worldwide director for refractive modern technologies at Bausch & Lomb, the company has no objective of presenting the NuVita lens right into the United States for FDA authorization or for scientific use. Rather, the firm is developing an entire brand-new phakic innovation for a foldable former 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, totally separate from the NuVita line. The brand-new, unrevealed lens system will be of a brand-new material, integrate a new foldable delivery system and also provide a new analysis tool for implantation.
According to Mr. Landreville, the firm intends to have the new system prepared for clinical usage in the USA 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. Worth, Texas) material as well as has several advantages over other phakic IOLs such as its foldability, which enables the lens to be put with a cut smaller than 3 mm, in addition to an angle-fixated, single-piece style and also high biocompatibility. The distance between the cornea and also the implant also falls between 2.96 mm as well as 3.35 mm, a larger distance than with some other lenses, he said.
Dr. Maxwell reported that of the 10 implants that have been executed to date, greater than 90% of the clients have 20/40 or better uncorrected vision at their postoperative check outs. The mean round matching in patients 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 recurring myopia.
” We see substantial enhancement in best-corrected visual acuity, and in all yet one person the postoperative finest corrected vision is much better than the most effective preoperative vision; in most cases, there are 2-, 3- or 4-line rises in best-corrected visual acuity,” Dr. Maxwell stated. “In the one instance where it wasn’t much better, it was the same as the preoperative skill.”
CIBA obtains licenses for IOL
CIBA Vision announced at the AAO meeting that it has obtained three licenses from Dr. Baikoff for foldable phakic former chamber IOL designs to deal with not just myopia and hyperopia however likewise presbyopia.
” We are very thrilled about this brand-new technology,” David Bailey, medical company system president for CIBA, stated. “We think that the MemoryLens material incorporated with these anterior chamber layouts will certainly be a very successful mix.”
That former chamber lens effort matches one more refractive implant that was the topic of numerous presentations in the CIBA Vision cubicle– the PRL. This posterior-chamber phakic dental implant is being established by Medennium Inc. CIBA Vision took a 10% equity stake in Medennium in July and also now holds unique globally advertising as well as distribution legal rights to the lens, which is presently in phase 2 professional tests.
” We are taking a solid setting in phakic IOLs,” Mr. Bailey said, “and we’ll be strengthening that position with more brand-new technology.”
This is the way to treat nearsightedness, ypermetropia and astigmatism (μυωπια ).