Emerging technology in the locations of corneal ring sections, holmium laser thermokeratoplasty (LTK) and phakic IOLs is supplying new options for individuals suffering from keratoconus, myopia, hyperopia and 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 patients with keratoconus. Of 23 eyes in 20 clients, 60% achieved a best-corrected visual acuity of 20/40 or far better. The mean postoperative keratometry was decreased by 3 D.
Daniel S. Durrie, MD, commented on Dr. Colin’s paper, which recommends a choice that strengthens the currently compromised cornea as opposed to more thinning it with LASIK. The concept of using an additive procedure, such as Intacs (KeraVision, Fremont, Calif.), to strengthen the cornea makes a lot of sense, Dr. Durrie told Health care Optometry News.
” For several years, we have actually looked at various other options to corneal transplants for these clients, as well as some treatments such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have actually been attempted in the past, but they remove part of the cornea in an individual population in which we understand the cornea is currently slim and weak,” Dr. Durrie said.
Because the keratoconic eye has a lump in the cornea, Dr. Durrie claimed, putting the Intacs put in the periphery of the cornea will certainly flatten the corneal facility. This not only decreases the degree of nearsightedness, yet strengthens the facility bulge, he said. The desired outcome is to postpone a corneal transplant for as long as possible.
While the data that Dr. Colin offered program that the treatment is fairly safe, stated Dr. Durrie, the longest term information offered are just 2 years. “Taking a look at the trends in the 3-month, 6-month as well as 1-year data, it shows up that all people gained from the treatment, yet we can not claim that it quit the keratoconus for longer than that up until additional data are collected,” he claimed. “Although I continue to do this procedure on separated instances, I inform patients we do not recognize the long-term effects and also we don’t recognize whether it will certainly decrease, accelerate or have no impact on the normal course of keratoconus.
” The advantage of this procedure is, if it doesn’t work, you can take the Intacs out and also have actually not weakened the cornea,” he continued. “If the individual does need to take place to a corneal transplant, the inserts can be secured and not interfere with standard transplant treatment. As a result of the adjustment in shape of the keratoconic cornea, ultimately, patients end up being call lens intolerant, as well as it is necessary to understand that there is a different to be explored for these individuals apart from simply referring them for a corneal transplant.”
Professionals ought to make sure that people recognize that the procedure is not refractive surgery and will not always fix their nearsightedness, said Dr. Durrie. “I have individuals on whom I have performed this treatment that have seen 20/40 without glasses, which would certainly be an impressive outcome after a corneal transplant, but they’re still wondering why their friends who have actually had Intacs implanted can see 20/20 when they can not,” he said. “That’s why these patients need to be informed that this isn’t something that keeps them from using glasses. It maintains them from needing a corneal transplant.”
Hyperopic change with LTK
picture– Post-LTK: The pulses are applied in 8 areas, one at the 6-mm zone as well as the various other at the 7-mm zone.
Professional research studies have actually revealed laser thermokeratoplasty (LTK) to be an effective method of correcting a person’s hyperopia, and also it might additionally hold assurance for treating presbyopia and also overcorrected nearsightedness after LASIK or PRK, claimed David J. Conway, OD, supervisor of refractive surgical procedure for Harvard Lead Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK method and its results with hyperopia making use of the Hyperion laser (Dawn Technologies International, Fremont, Calif.) at the International Society of Refractive Surgical procedure’s Summertime Globe Refractive Surgical Treatment Symposium 2000. Dr. Conway was not involved in any type of Food and Drug Administration (FDA) research study; his ISRS presentation was based on info from the Sunup FDA investigations and talks he participated in.
When treating an individual for hyperopia, the specialist requires to stress the impermanence of the treatment, he said. “You require to share to the client that this is only a momentary adjustment in his or her hyperopic condition,” he claimed. “There is enough regression with this method that the FDA felt it required to refer this.”
Any type of treatment for the improvement of hyperopia might necessitate retreatment gradually; this is not special to LTK, stated Sandra Belmont, MD, director of the laser vision facility at the Cornell Weill Medical Center in New York City City. “Hyperopia increases as you age,” she said. “We have clients 3 years out that are secure, so I’m extremely pleased with the results.”
Dr. Belmont informs people of this possibility, but none of them have actually changed their minds. She said that if retreatment were needed, individuals did not mind since the treatment is quick, and also producing a flap, which can lead to complications, is not required.
The LTK treatment
photograph– Security: One researcher has clients who are still secure 3 years post-LTK.
The procedure, Dr. Conway said, takes 3 seconds to perform. Seven pulses are used in 8 areas, twice back to back, one at the 6-mm area as well as the other at the 7-mm area. The FDA research study reported that the 612 eyes in 379 patients, 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 kept in mind.
” No loss of lines of acuity were attributable to the LTK,” he stated. “In contrasting preop to 24 months later on, there was no loss of BSCVA as well as a little of gain. We know that myopes as well as hyperopes are really various. Luckily, the tolerance of hyperopes is extremely handy in making their fulfillment level really high.”
Prior to the treatment, clients receive 3 consecutive administrations of topical proparacaine at 3-minute intervals. Problems were minimal, Dr. Conway kept in mind.
” Clients are typically taken care of from a comfort perspective, purely with over-the-counter anesthetics to obtain them through the initial hours of recovery,” he stated. “Due to the fact that you’re working on the corneal surface area, FDA investigators reported a little bit of foreign-body feeling, which dissipates with time really perfectly.”
Dr. Conway stated that, while the client’s skill degree stays fairly secure, some regression is evident as the hyperopia raises over time. “There will certainly be a small but considerable regression in these patients; it’s just a matter of whether it’s at a reduced enough level to warrant the individual’s cost as well as experience of undertaking this technique,” he said. “By contrasting your cycloplegic to your manifest refraction, you can tell whether it’s latent hyperopia or not.”
A client’s age consider to for how long the impact of LTK might last, stated Dr. Conway. “A 50-year-old individual will experience a bit extra result than a 40-year-old individual, probably because of a little more dry skin or the collagen standing of the cornea,” he stated.
An off-label indicator of LTK is the therapy of presbyopia, stated Dr. Belmont. Patients who are plano as well as presbyopic may be treated with LTK to attain monovision, she said. “Immediately, their reading vision comes into emphasis,” she said. “They obtain their results immediately, as well as they’re actually happy with that.”
People that have actually been treated for presbyopia typically will experience the very same degree of regression as hyperopes, Dr. Belmont kept in mind. “Presbyopia enhances as you age, as does hyperopia,” she stated. “Individuals understand that this treatment will need to be enhanced as their aging requires a boost in the power they’ll need to review. They’re happy as long as you tell them in advance. I anticipate this as being the procedure to deal with farsightedness and also presbyopia.”
The length of time needed for presbyopic treatment is the same as for that of hyperopia, yet the degree of power that is applied to the eye is differed, she said.
The treatment might likewise confirm to be a valid choice for boosting myopic clients who have been overcorrected with LASIK or PRK, claimed Dr. Conway. “This values a lot of consideration, due to the fact that you don’t have to remove any type of tissue,” he said. “Additionally, Sunup is submitting for authorization remediation of presbyopia, making people nearsighted in a monovision style. So, I assume this will certainly come to be a rather popular as well as usual alternative in this individual populace, and we’ll see how many more specialists decide to embrace it.”
LTK is authorized for approximately +2.5 D, said Dr. Belmont, as well as is presently undertaking trials for treatment approximately +5.6 D.
Refractec’s conductive keratoplasty
Preliminary clinical trials suggest that conductive keratoplasty (CK) making use of Refractec’s (Irvine, Calif.) radiofrequency approach is possibly risk-free and also effective for fixing reduced to modest quantities of hyperopia, according to Penny A. Asbell, MD, who presented clinical test information in Miami at the International Society of Refractive Surgery meeting. “Very early outcomes with our information bent on one year suggest that we get great visual acuity, great security as well as really no adverse events, such as loss of vision,” said Dr. Asbell.
CK warms the stromal tissue with an electric present, shrinks the collagen as well as steepens the main cornea, Dr. Asbell clarified. A high-frequency current is used directly right into the outer corneal stroma through a distribution idea inserted at 8 or more treatment points. The release of radiofrequency energy heats up the bordering collagen to a homogenous temperature level 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 enhances its curvature to lower hyperopia.
” The change appears to be irreversible, and also I believe among the reasons that holds true is that the treatment is supplied directly to the stroma,” stated Dr. Asbell. “That’s where you desire the effect– out the endothelium, out the epithelium. It’s a very easy medical technique. It’s a non-laser technique, as well as it adds another measurement to what we already can provide for refractive surgical treatment– it is an affordable procedure,” she added.
Another key issue, Dr. Asbell explained, is that CK is a regular therapy. “The treatment size as well as the zone result in the stroma correspond from therapy place to treatment area,” she stated. “One of the essential issues to remember is that the temperature we get with the CK treatment is always 65 ° and the imprint you make within the outer corneal stroma is constantly the very same: 100 µm broad and also 500 µm deep within the corneal stroma.”
Dr. Asbell is an investigator in the FDA medical trial of CK. Fellow detectives at various other websites include 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 stated, there is a fairly large range old among the test’s individuals. To qualify for the trial, she clarified, individuals had to have uncorrected visual acuity of a minimum of 20/40 or even worse as well as poor near vision also– common 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 and simplicity of the treatment. “This procedure takes 5 minutes per eye. It is an extremely short procedure; you remain in and also out extremely promptly,” she claimed. “It is an operation, yet a really simple one. It does not need a trained technician [to aid] It does not also need an autoclave. The idea, which is about the width of a hair, is non reusable.”
Dr. Asbell explained 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 therapy zone] The level of hyperopia you are correcting figures out the number of treatment marks on the cornea. Each one coincides– the very same amount of energy as well as the very same deepness within the stroma in each area,” she claimed.
Outcomes appear steady
Of the people on whom Dr. Asbell reported, 61% achieved uncorrected visual acuity of 20/20 or far 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 better, and also 92% were 20/40 or far better. “Our outcomes look good and secure. These are really happy individuals,” stated Dr. Asbell. “They really can go back to function right away or definitely the following day if they so choose. No one takes pain medications.”
Safety and security variables were “primarily absolutely no,” Dr. Asbell reported. “There was no loss of vision as well as no corneal edema,” she stated. “I assume this is going to be a treatment and a machine that’s mosting likely to be easy for us to have and also to utilize and an outstanding means to remedy hyperopia postop LASIK or to repair a postop cataract or corneal transplant,” she claimed. “I believe it’s mosting likely to have a great deal of adaptability in terms of its uses for remedying hyperopia as well as potentially astigmatism.”
Broadened scientific tests of LAPR
SurgiLight Inc. (Orlando, Fla.) has broadened its scientific test research studies of laser presbyopia turnaround (LAPR) using its IR-laser in Venezuela, Argentina, Brazil, the Bahamas and also Japan. Also, the company has scheduled setup of the IR-laser in some European nations.
SurgiLight has actually sent 4 papers to the American Culture of Cataract as well as Refractive Surgical Procedure for the May 2001 conference, where more than 500 instances of LAPR will certainly be presented by eye doctors from various nations utilizing the firm’s IR laser.
The firm is in the process of acquiring CE-Mark qualification and also selecting various worldwide suppliers. It prepares to send extra 510K applications based on certain clearances obtained from Premier Laser Solutions. SurgiLight expects to bill an aristocracy charge of $500 per individual to surgeons who use the business’s IR-3000 system in the United States and 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 offered for myopes varying from 7 D to 20 D. The design is an angle-fixated, single-piece lens, with a curve optical form and also a PMMA surface. The general optical diameter is 5 mm as well as the overall length of the NuVita varies from 12 mm to 13.5 mm in 0.5-mm increments.
The optic, loop as well as footplate were all revamped from the previous variation to lower refracted glare, pressure in the angle and better clearance of the iris and also all-natural lens. Additionally, the haptics were revamped to remove iris retraction. The haptics were made much more versatile and also, consequently, led to much less pupil ovalization.
In its second generation, the fluorine plasma treatment was included in the production process to produce covalent bonds of fluorocarbon radicals with the PMMA surface area, which yielded lower surface energy and remarkably smooth finish. The fluorine therapy considerably enhanced biocompatibility.
In studies carried out by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes implanted revealed a precision price of ± 0.5 D while 97% revealed a precision rate of ± 2 D. In regards to security, the BSCVA rates had 47 acquiring at the very least 2 lines, and no eyes lost lines. The total glare record revealed that the majority of clients had few troubles.
According to Mike Landreville, global supervisor for refractive technologies at Bausch & Lomb, the business has no intent of presenting the NuVita lens into the United States for FDA approval or for professional use. Instead, the business is establishing an entire new phakic technology for a collapsible anterior chamber phakic lens. The new phakic lens will certainly not only exist as a new lens, yet as part of a completely brand-new system, completely separate from the NuVita line. The new, unnamed lens system will certainly be of a new product, integrate a new foldable shipment system as well as supply a brand-new diagnostic device for implantation.
According to Mr. Landreville, the company prepares to have the brand-new system prepared for professional use 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) material and also has a number of benefits over various other phakic IOLs such as its foldability, which permits the lens to be put through a cut smaller sized than 3 mm, along with an angle-fixated, single-piece layout as well as high biocompatibility. The range in between the cornea and also the implant also drops in between 2.96 mm and also 3.35 mm, a larger range than with some other lenses, he said.
Dr. Maxwell reported that of the 10 implants that have been done to day, more than 90% of the patients have 20/40 or far better uncorrected vision at their postoperative sees. The mean spherical equivalent in people implanted so far was– 11.5 D, he stated, with a result of– 0.39 D at 1 month and also– 0.8 D at 6 months of residual nearsightedness.
” We see considerable improvement in best-corrected visual acuity, and also in all however one person the postoperative finest remedied vision is better than the very best 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 case where it had not been better, it coincided as the preoperative skill.”
CIBA gets licenses for IOL
CIBA Vision announced at the AAO conference that it has actually gotten 3 patents from Dr. Baikoff for collapsible phakic anterior chamber IOL makes to correct not just nearsightedness and hyperopia yet likewise presbyopia.
” We are extremely delighted about this brand-new modern technology,” David Bailey, medical organization device head of state for CIBA, said. “We assume that the MemoryLens product incorporated with these anterior chamber layouts will certainly be a very successful combination.”
That anterior chamber lens campaign complements an additional refractive implant that was the subject of a number of discussions in the CIBA Vision booth– the PRL. This posterior-chamber phakic dental implant is being established by Medennium Inc. CIBA Vision took a 10% equity risk in Medennium in July and also now holds unique worldwide advertising and marketing 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 ).