Emerging modern technology in the locations of corneal ring sections, holmium laser thermokeratoplasty (LTK) and also phakic IOLs is giving brand-new options for clients experiencing keratoconus, myopia, hyperopia and presbyopia.
Intacs for keratoconus
At the American Academy of Ophthalmology (AAO) meeting in October 2000, Joseph Colin, MD, offered a research of alternatives to permeating keratoplasty for people with keratoconus. Of 23 eyes in 20 individuals, 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, commented on Dr. Colin’s paper, which recommends an alternative that reinforces the currently compromised cornea instead of 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 informed Primary Care Optometry News.
” For several years, we have actually taken a look at other options to corneal transplants for these patients, as well as some procedures such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have been tried in the past, however they eliminate part of the cornea in a patient population in which we understand the cornea is already thin and weak,” Dr. Durrie stated.
Because the keratoconic eye has a bulge in the cornea, Dr. Durrie claimed, positioning the Intacs place in the periphery of the cornea will certainly flatten the corneal center. This not just lowers the level of myopia, however enhances the facility lump, he said. The preferred result is to delay a corneal transplant for as long as possible.
While the information that Dr. Colin offered program that the treatment is quite safe, claimed Dr. Durrie, the lengthiest term information readily available are just 2 years. “Considering the patterns in the 3-month, 6-month and 1-year data, it appears that all patients benefited from the treatment, however we can’t state that it quit the keratoconus for longer than that up until additional information are built up,” he stated. “Although I remain to do this treatment on isolated cases, I inform clients we don’t recognize the lasting effects and we do not recognize whether it will decrease, accelerate or have no result on the normal course of keratoconus.
” The benefit of this procedure is, if it does not work, you can take the Intacs out and also have actually not deteriorated the cornea,” he proceeded. “If the person does need to go on to a corneal transplant, the inserts can be obtained and not interfere with basic transplant treatment. Because of the modification in shape of the keratoconic cornea, eventually, patients end up being call lens intolerant, as well as it is necessary to understand that there is an alternate to be explored for these clients apart from just referring them for a corneal transplant.”
Experts need to make certain that patients understand that the procedure is not refractive surgical procedure as well as will not necessarily remedy their nearsightedness, said Dr. Durrie. “I have patients on whom I have actually done this treatment that have seen 20/40 without glasses, which would certainly be an impressive outcome after a corneal transplant, however they’re still questioning why their friends who have had Intacs dental implanted can see 20/20 when they can’t,” he claimed. “That’s why these patients need to be educated that this isn’t something that keeps them from wearing glasses. It keeps them from requiring a corneal transplant.”
Hyperopic change with LTK
photo– Post-LTK: The pulses are used in 8 spots, one at the 6-mm zone and the other at the 7-mm area.
Clinical researches have actually revealed laser thermokeratoplasty (LTK) to be an efficient approach of dealing with an individual’s hyperopia, as well as it may likewise hold pledge for treating presbyopia and also overcorrected myopia after LASIK or PRK, claimed David J. Conway, OD, manager of refractive surgical treatment for Harvard Vanguard Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK technique and also its results with hyperopia utilizing the Hyperion laser (Sunup Technologies International, Fremont, Calif.) at the International Culture of Refractive Surgical treatment’s Summertime World Refractive Surgical Treatment Symposium 2000. Dr. Conway was not associated with any kind of Fda (FDA) research study; his ISRS presentation was based upon details from the Daybreak FDA examinations as well as talks he participated in.
When dealing with a client for hyperopia, the practitioner requires to worry the impermanence of the treatment, he claimed. “You require to share to the patient that this is just a momentary change in his or her hyperopic status,” he claimed. “There suffices regression with this strategy that the FDA felt it essential to make mention of this.”
Any kind of treatment for the improvement of hyperopia might necessitate retreatment with time; this is not unique to LTK, stated Sandra Belmont, MD, supervisor of the laser vision facility at the Cornell Weill Medical Facility in New York City City. “Hyperopia boosts as you age,” she claimed. “We have individuals 3 years out who are secure, so I’m really satisfied with the outcomes.”
Dr. Belmont informs people of this opportunity, however none have actually changed their minds. She said that if retreatment were required, patients did not mind since the procedure is quick, and developing a flap, which can lead to issues, is not required.
The LTK procedure
picture– Stability: One scientist has people that are still steady 3 years post-LTK.
The procedure, Dr. Conway claimed, takes 3 seconds to do. 7 pulses are used in eight places, twice consecutively, one at the 6-mm area and the other at the 7-mm zone. The FDA research reported that the 612 eyes in 379 clients, all older than 40, varying from +0.75 to +2.50 D, saw no loss in finest 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 as well as a bit of gain. We understand that myopes and also hyperopes are really various. Thankfully, the tolerance of hyperopes is really valuable in making their satisfaction degree really high.”
Prior to the treatment, patients receive three consecutive managements of topical proparacaine at 3-minute intervals. Problems were marginal, Dr. Conway kept in mind.
” Clients are usually handled from a comfort standpoint, strictly with non-prescription analgesics to get them via the very first hrs of healing,” he claimed. “Since you’re working with the corneal surface, FDA detectives reported a little bit of foreign-body experience, which dissipates with time very nicely.”
Regression in time
Dr. Conway claimed that, while the patient’s skill level stays relatively stable, some regression appears as the hyperopia increases with time. “There will certainly be a small but considerable regression in these clients; it’s simply an issue of whether it goes to a low adequate degree to validate the patient’s price as well as experience of undertaking this strategy,” he stated. “By contrasting your cycloplegic to your show refraction, you can tell whether it exists hyperopia or otherwise.”
A client’s age consider to how much time the result of LTK may last, claimed Dr. Conway. “A 50-year-old patient will experience a bit much more impact than a 40-year-old patient, maybe because of a little extra dryness or the collagen standing of the cornea,” he claimed.
An off-label indication of LTK is the treatment of presbyopia, stated Dr. Belmont. Individuals who are plano as well as presbyopic might be treated with LTK to accomplish monovision, she stated. “Immediately, their analysis vision enters into emphasis,” she claimed. “They get their outcomes instantly, and they’re actually satisfied keeping that.”
Clients who have actually been treated for presbyopia commonly will come across the same level of regression as hyperopes, Dr. Belmont noted. “Presbyopia increases as you age, as does hyperopia,” she said. “Individuals understand that this procedure will have 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 treatment to deal with farsightedness as well as presbyopia.”
The length of time required for presbyopic therapy is the same as for that of hyperopia, however the degree of power that is related to the eye is varied, she claimed.
The procedure might additionally show to be a valid option for boosting myopic people who have actually been overcorrected with LASIK or PRK, claimed Dr. Conway. “This values a great deal of consideration, since you do not need to get rid of any cells,” he claimed. “In addition, Daybreak is submitting for approval remediation of presbyopia, making individuals myopic in a monovision fashion. So, I think this will become a rather prominent as well as typical alternative in this person populace, as well as we’ll see the amount of even more specialists make a decision to accept it.”
LTK is authorized for approximately +2.5 D, claimed Dr. Belmont, and is presently undertaking tests for treatment as much as +5.6 D.
Refractec’s conductive keratoplasty
Preliminary scientific trials recommend that conductive keratoplasty (CK) using Refractec’s (Irvine, Calif.) radiofrequency approach is probably secure as well as effective for fixing low to modest quantities of hyperopia, according to Penny A. Asbell, MD, who presented medical test information in Miami at the International Society of Refractive Surgical procedure meeting. “Very early results with our information bent on 12 months recommend that we get great visual acuity, great stability and also really no adverse occasions, such as loss of vision,” said Dr. Asbell.
CK heats up the stromal tissue with an electric current, reduces the collagen as well as steepens the main cornea, Dr. Asbell explained. A high-frequency current is applied straight into the peripheral corneal stroma through a shipment idea inserted at eight or more therapy points. The launch of radiofrequency energy heats the surrounding collagen to an identical temperature of 65 ° C and also generates a round impact 500 µm deep vs. a shallower, conelike impact made with the LTK technique. A cycle of CK-treated places cinches the cornea as well as raises its curvature to decrease hyperopia.
” The modification appears to be irreversible, and also I think one of the reasons that holds true is that the treatment is provided straight to the stroma,” claimed Dr. Asbell. “That’s where you want the effect– not on the endothelium, not on the epithelium. It’s a very easy surgical strategy. It’s a non-laser technique, and also it includes one more dimension to what we currently can provide for refractive surgical treatment– it is a cost-efficient treatment,” she added.
CK is consistent
Another crucial issue, Dr. Asbell explained, is that CK is a constant therapy. “The treatment size and also the zone impact in the stroma are consistent from therapy area to therapy place,” she said. “Among the essential concerns to remember is that the temperature level we get with the CK procedure is always 65 ° and also the imprint you make within the outer corneal stroma is always the very same: 100 µm large and 500 µm deep within the corneal stroma.”
Dr. Asbell is a private investigator in the FDA medical trial of CK. Fellow private investigators at various other websites 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 typical age was 55, although, she said, there is a fairly large range old among the test’s participants. To get approved for the test, she explained, people had to have uncorrected visual acuity of at the very least 20/40 or worse as well as bad near vision as well– typical for a hyperope. “We are fixing from 1 D to 4 D of hyperopia, with little or no astigmatism,” Dr. Asbell reported.
She emphasized the speed as well as simpleness of the procedure. “This treatment takes 5 mins per eye. It is a very short procedure; you remain in as well as out extremely rapidly,” she claimed. “It is an operation, but an extremely simple one. It does not call for a qualified professional [to assist] It doesn’t even require an autoclave. The tip, which is about the width of a hair, is non reusable.”
Dr. Asbell defined the CK nomogram thus: “The treatment is either at 6 mm, 7 mm or 8 mm. You make a mark on the cornea [showing the dimension of the therapy area] The degree of hyperopia you are remedying identifies the variety of treatment marks on the cornea. Each one is the same– the exact same quantity of energy as well as the very same deepness within the stroma in each area,” she said.
Results appear steady
Of the patients 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 better at the 6-month mark. One year postoperatively, 62% were 20/20 or better, and also 92% were 20/40 or far better. “Our results look good as well as stable. These are very satisfied clients,” claimed Dr. Asbell. “They in fact can go back to work immediately or absolutely the next day if they so select. No one takes pain medicines.”
Safety and security variables were “primarily no,” Dr. Asbell reported. “There was no loss of vision and also no corneal edema,” she said. “I believe this is going to be a treatment and a maker that’s going to be simple for us to have and to use and an outstanding method to deal with hyperopia postop LASIK or to retouch a postop cataract or corneal transplant,” she claimed. “I think it’s mosting likely to have a lot of adaptability in terms of its uses for correcting hyperopia and also perhaps astigmatism.”
Expanded scientific tests of LAPR
SurgiLight Inc. (Orlando, Fla.) has actually expanded its professional test 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 setup of the IR-laser in some European countries.
SurgiLight has actually submitted four papers to the American Culture of Cataract as well as Refractive Surgical Procedure for the May 2001 meeting, where more than 500 cases of LAPR will be presented by eye doctors from various countries using the business’s IR laser.
The company is in the process of obtaining CE-Mark certification as well as choosing numerous worldwide suppliers. It plans to submit extra 510K applications based upon certain clearances obtained from Premier Laser Equipments. SurgiLight expects to charge an aristocracy charge of $500 per client to specialists that utilize the firm’s IR-3000 system in the United States and also 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 design is an angle-fixated, single-piece lens, with a crescent optical form and a PMMA surface area. The general optical diameter is 5 mm and the total size of the NuVita varies from 12 mm to 13.5 mm in 0.5-mm increments.
The optic, loop and footplate were all upgraded from the previous version to reduce refracted glare, stress in the angle and also better clearance of the iris and natural lens. Additionally, the haptics were revamped to remove iris retraction. The haptics were made a lot more adaptable as well as, consequently, resulted in less student ovalization.
In its 2nd generation, the fluorine plasma therapy was included in the production procedure to create covalent bonds of fluorocarbon radicals with the PMMA surface, which generated reduced surface power and remarkably 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 dental implanted showed an accuracy rate of ± 0.5 D while 97% showed an accuracy price of ± 2 D. In terms of security, the BSCVA rates had 47 gaining at the very least 2 lines, and no eyes lost lines. The total glow record showed that many individuals had few issues.
According to Mike Landreville, global director for refractive technologies at Bausch & Lomb, the business has no purpose of presenting the NuVita lens into the United States for FDA approval or for scientific use. Rather, the company is developing an entire brand-new phakic technology for a collapsible anterior chamber phakic lens. The brand-new phakic lens will not only exist as a brand-new lens, but as part of a totally brand-new system, completely different from the NuVita line. The new, unrevealed lens system will be of a brand-new product, incorporate a brand-new collapsible distribution system and also supply a new diagnostic tool for implantation.
According to Mr. Landreville, the company intends to have the new system ready for clinical usage in the USA by this year.
Alcon phakic IOL
A new anterior chamber phakic IOL existed by Andrew Maxwell, MD, PhD, at the AAO meeting. The lens has an Acrysof-based (Alcon, Ft. Well Worth, Texas) product and has numerous benefits over other phakic IOLs such as its foldability, which enables the lens to be placed with a cut smaller sized than 3 mm, in addition to an angle-fixated, single-piece layout as well as high biocompatibility. The distance in between the cornea as well as the dental implant additionally drops in between 2.96 mm and 3.35 mm, a bigger distance than with some other lenses, he stated.
Dr. Maxwell reported that of the 10 implants that have actually been done to day, more than 90% of the people have 20/40 or much better uncorrected vision at their postoperative sees. The mean round equivalent in clients dental implanted so far was– 11.5 D, he stated, with a result of– 0.39 D at 1 month and– 0.8 D at 6 months of residual myopia.
” We see considerable renovation in best-corrected visual acuity, and also in all however one patient the postoperative best dealt with vision is far better than the best preoperative vision; in most cases, there are 2-, 3- or 4-line boosts in best-corrected visual acuity,” Dr. Maxwell said. “In the one case where it wasn’t much better, it was the same as the preoperative skill.”
CIBA gets licenses for IOL
CIBA Vision revealed at the AAO meeting that it has actually obtained 3 patents from Dr. Baikoff for collapsible phakic anterior chamber IOL designs to remedy not only myopia and also hyperopia however also presbyopia.
” We are really excited about this brand-new modern technology,” David Bailey, surgical company unit head of state for CIBA, claimed. “We think that the MemoryLens material combined with these former chamber styles will be a very successful combination.”
That former chamber lens campaign matches another refractive dental implant that was the subject of numerous presentations 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 also currently holds special worldwide advertising and marketing and also distribution civil liberties to the lens, which is presently in phase 2 scientific trials.
” We are taking a strong position in phakic IOLs,” Mr. Bailey claimed, “as well as we’ll be enhancing that position with even more brand-new technology.”
This is the method to deal with nearsightedness, ypermetropia as well as astigmatism (μυωπια ).