Arising modern technology in the areas of corneal ring segments, holmium laser thermokeratoplasty (LTK) and also phakic IOLs is supplying new alternatives for clients dealing 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, provided a study of options to permeating keratoplasty for people with keratoconus. Of 23 eyes in 20 patients, 60% accomplished a best-corrected visual acuity of 20/40 or far better. The mean postoperative keratometry was decreased by 3 D.
Daniel S. Durrie, MD, discussed Dr. Colin’s paper, which suggests a choice that strengthens the currently weakened cornea as opposed to further thinning it with LASIK. The suggestion of using an additive procedure, such as Intacs (KeraVision, Fremont, Calif.), to reinforce the cornea makes a great deal of sense, Dr. Durrie informed Medical care Optometry News.
” For several years, we have actually looked at other options to corneal transplants for these individuals, and also some treatments such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have actually been attempted in the past, yet they eliminate part of the cornea in a person populace in which we know the cornea is already thin as well as weak,” Dr. Durrie said.
Since the keratoconic eye has a lump in the cornea, Dr. Durrie stated, placing the Intacs place in the perimeter of the cornea will certainly flatten the corneal facility. This not just reduces the degree of myopia, yet reinforces the center lump, he stated. The wanted result is to postpone a corneal transplant for as long as feasible.
While the data that Dr. Colin presented show that the procedure is fairly secure, claimed Dr. Durrie, the longest term information available are just 2 years. “Considering the fads in the 3-month, 6-month and also 1-year information, it appears that all individuals benefited from the treatment, yet we can’t say that it quit the keratoconus for longer than that till further information are collected,” he said. “Although I remain to do this procedure on isolated instances, I tell individuals we do not know the long-lasting impacts and we don’t know whether it will certainly slow down, accelerate or have no result on the normal course of keratoconus.
” The advantage of this treatment is, if it does not function, you can take the Intacs out as well as have actually not damaged the cornea,” he continued. “If the patient does require to go on to a corneal transplant, the inserts can be secured and not interfere with common transplant therapy. Because of the change in shape of the keratoconic cornea, ultimately, individuals come to be get in touch with lens intolerant, as well as it’s important to know that there is a different to be explored for these individuals apart from simply referring them for a corneal transplant.”
Specialists need to make sure that patients understand that the treatment is not refractive surgical procedure and also will certainly not necessarily correct their nearsightedness, stated Dr. Durrie. “I have patients on whom I have actually performed this treatment who have seen 20/40 without glasses, which would be an impressive result after a corneal transplant, however they’re still questioning why their pals who have had Intacs dental implanted can see 20/20 when they can’t,” he stated. “That’s why these people need to be enlightened that this isn’t something that keeps them from putting on glasses. It maintains them from requiring a corneal transplant.”
Hyperopic change with LTK
photo– Post-LTK: The pulses are used in eight areas, one at the 6-mm area and also the various other at the 7-mm area.
Professional researches have shown laser thermokeratoplasty (LTK) to be an efficient technique of remedying a patient’s hyperopia, and it may additionally hold pledge for dealing with presbyopia as well as overcorrected myopia after LASIK or PRK, said David J. Conway, OD, manager of refractive surgical treatment for Harvard Vanguard Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK strategy and its results with hyperopia utilizing the Hyperion laser (Sunrise Technologies International, Fremont, Calif.) at the International Culture of Refractive Surgery’s Summer Globe Refractive Surgery Symposium 2000. Dr. Conway was not involved in any Food and Drug Administration (FDA) study; his ISRS presentation was based on info from the Dawn FDA examinations and also talks he went to.
When treating an individual for hyperopia, the practitioner needs to stress the brevity of the treatment, he stated. “You need to share to the person that this is just a temporary adjustment in his/her hyperopic status,” he stated. “There is enough regression with this technique that the FDA felt it necessary to refer this.”
Any treatment for the modification of hyperopia might necessitate retreatment gradually; this is not special to LTK, claimed Sandra Belmont, MD, director of the laser vision center at the Cornell Weill Medical Center in New York City. “Hyperopia boosts as you age,” she said. “We have patients 3 years out who are secure, so I’m extremely delighted with the outcomes.”
Dr. Belmont informs clients of this possibility, but none of them have actually transformed their minds. She said that if retreatment were needed, clients did not mind because the procedure is quick, as well as developing a flap, which can result in problems, is not required.
The LTK treatment
picture– Security: One scientist has patients who are still secure 3 years post-LTK.
The treatment, Dr. Conway stated, takes 3 secs to do. Seven pulses are used in 8 places, two times back to back, one at the 6-mm zone and also the other at the 7-mm area. The FDA 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 noted.
” No loss of lines of skill were attributable to the LTK,” he said. “In comparing preop to 24 months later on, there was no loss of BSCVA and also a bit of gain. We understand that myopes and also hyperopes are very various. Fortunately, the tolerance of hyperopes is really handy in making their satisfaction degree extremely high.”
Before the treatment, patients receive three consecutive administrations of topical proparacaine at 3-minute intervals. Problems were marginal, Dr. Conway noted.
” People are typically taken care of from a comfort viewpoint, purely with over-the-counter analgesics to get them through the very first hrs of recuperation,” he claimed. “Because you’re dealing with the corneal surface, FDA detectives reported a little of foreign-body sensation, which dissipates with time really well.”
Regression in time
Dr. Conway said that, while the individual’s acuity level stays fairly secure, some regression appears as the hyperopia increases with time. “There will certainly be a little yet significant regression in these clients; it’s simply an issue of whether it’s at a low adequate degree to validate the patient’s price and also experience of undertaking this strategy,” he stated. “By comparing your cycloplegic to your manifest refraction, you can inform whether it exists hyperopia or otherwise.”
An individual’s age factors in to how much time the result of LTK might last, said Dr. Conway. “A 50-year-old patient will certainly experience a little much more result than a 40-year-old patient, maybe due to a little bit extra dryness or the collagen status of the cornea,” he stated.
An off-label sign of LTK is the treatment of presbyopia, claimed Dr. Belmont. People that are plano and presbyopic may be treated with LTK to accomplish monovision, she stated. “Immediately, their reading vision comes into focus,” she said. “They obtain their outcomes right away, and they’re truly delighted with that said.”
Patients who have been treated for presbyopia generally will come across the exact same degree of regression as hyperopes, Dr. Belmont kept in mind. “Presbyopia raises as you age, as does hyperopia,” she stated. “Patients understand that this procedure will have to be enhanced as their aging demands a boost in the power they’ll need to check out. They enjoy as long as you tell them ahead of time. I anticipate this as being the procedure to treat farsightedness as well as presbyopia.”
The length of time needed for presbyopic therapy is the same when it comes to that of hyperopia, however the degree of energy that is applied to the eye is differed, she said.
The procedure might additionally show to be a valid option for improving myopic patients that have been overcorrected with LASIK or PRK, said Dr. Conway. “This benefits a great deal of factor to consider, because you do not need to remove any cells,” he said. “Additionally, Daybreak is submitting for approval remediation of presbyopia, making people short-sighted in a monovision style. So, I believe this will end up being a relatively preferred as well as common alternative in this patient populace, as well as we’ll see how many even more cosmetic surgeons make a decision to embrace it.”
LTK is accepted for up to +2.5 D, said Dr. Belmont, and also is presently undertaking tests for therapy as much as +5.6 D.
Refractec’s conductive keratoplasty
Initial medical tests recommend that conductive keratoplasty (CK) using Refractec’s (Irvine, Calif.) radiofrequency approach is possibly secure and also effective for correcting reduced to modest amounts of hyperopia, according to Cent A. Asbell, MD, who presented scientific trial information in Miami at the International Culture of Refractive Surgical procedure conference. “Early results with our data bent on one year suggest that we get great visual acuity, great security and also actually no unfavorable occasions, such as loss of vision,” stated Dr. Asbell.
CK warms the stromal tissue with an electric existing, reduces the collagen and also steepens the main cornea, Dr. Asbell clarified. A high-frequency present is applied directly into the peripheral corneal stroma with a delivery idea put at 8 or even more therapy factors. The launch of radiofrequency energy heats up the bordering collagen to an identical temperature of 65 ° C and creates a cylindrical impact 500 µm deep vs. a shallower, conical impact made with the LTK strategy. A cycle of CK-treated spots cinches the cornea and also enhances its curvature to reduce hyperopia.
” The change appears to be long-term, as well as I think among the reasons that holds true is that the treatment is provided directly to the stroma,” said Dr. Asbell. “That’s where you want the result– out the endothelium, not on the epithelium. It’s a really easy medical technique. It’s a non-laser strategy, as well as it includes one more measurement to what we currently can supply for refractive surgical treatment– it is a cost-efficient treatment,” she added.
Another vital issue, Dr. Asbell pointed out, is that CK is a constant therapy. “The therapy size and also the area result in the stroma correspond from treatment area to therapy place,” she said. “One of the key issues to remember is that the temperature we get with the CK treatment is always 65 ° and also the imprint you make within the peripheral corneal stroma is always the exact same: 100 µm broad and also 500 µm deep within the corneal stroma.”
Dr. Asbell is an investigator in the FDA scientific test of CK. Fellow investigators at various other websites include 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 variety old among the trial’s individuals. To get approved for the trial, she explained, clients needed to have uncorrected visual acuity of a minimum of 20/40 or worse as well as inadequate near vision also– common 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 rate and simplicity of the procedure. “This treatment takes 5 mins per eye. It is a very brief treatment; you’re in and out really quickly,” she said. “It is a procedure, but a really basic one. It does not call for an experienced technician [to assist] It does not also call for an autoclave. The tip, which has to do with the size of a hair, is disposable.”
Dr. Asbell explained the CK nomogram thus: “The treatment 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 dealing with determines the number of therapy marks on the cornea. Every one is the same– the exact same quantity of energy as well as the exact same deepness within the stroma in each place,” she stated.
Outcomes appear stable
Of the individuals on whom Dr. Asbell reported, 61% accomplished uncorrected visual acuity of 20/20 or far better 6 months postoperatively as well as 96% were 20/40 or much better at the 6-month mark. One year postoperatively, 62% were 20/20 or far better, and also 92% were 20/40 or far better. “Our outcomes look good as well as secure. These are extremely satisfied clients,” claimed Dr. Asbell. “They really can return to work promptly or absolutely the next day if they so select. No one takes discomfort medications.”
Safety variables were “essentially zero,” Dr. Asbell reported. “There was no loss of vision and also no corneal edema,” she stated. “I believe this is mosting likely to be a treatment and a device that’s mosting likely to be very easy for us to have and to use and an outstanding means to deal with hyperopia postop LASIK or to repair a postop cataract or corneal transplant,” she claimed. “I think it’s going to have a great deal of flexibility in terms of its uses for correcting hyperopia and also possibly astigmatism.”
Increased medical trials of LAPR
SurgiLight Inc. (Orlando, Fla.) has broadened its scientific test research studies of laser presbyopia reversal (LAPR) utilizing its IR-laser in Venezuela, Argentina, Brazil, the Bahamas as well as Japan. Also, the firm has scheduled installment of the IR-laser in some European countries.
SurgiLight has submitted 4 documents to the American Culture of Cataract as well as Refractive Surgical Procedure for the May 2001 conference, where greater than 500 situations of LAPR will certainly exist by ophthalmologists from numerous countries utilizing the firm’s IR laser.
The firm is in the procedure of obtaining CE-Mark certification as well as selecting different worldwide suppliers. It intends to submit added 510K applications based on particular clearances obtained from Premier Laser Solutions. SurgiLight expects to bill a nobility fee of $500 per individual to cosmetic surgeons who make use of the firm’s IR-3000 system in the USA and Europe.
B&L NuVita phakic IOL
The 3rd generation of George Baikoff, MD’s, former chamber phakic IOL is represented with Bausch & Lomb’s (St. Louis) NuVita MA20. The lens is available for myopes varying from 7 D to 20 D. The design is an angle-fixated, single-piece lens, with a meniscus optical form and also a PMMA surface. The general optical size is 5 mm and the general size of the NuVita ranges from 12 mm to 13.5 mm in 0.5-mm increments.
The optic, loop as well as footplate were all redesigned from the previous version to decrease refracted glare, pressure in the angle as well as better clearance of the iris and all-natural lens. Likewise, the haptics were upgraded to eliminate iris retraction. The haptics were made a lot more flexible and also, therefore, led to much less student ovalization.
In its second generation, the fluorine plasma therapy was included in the production process to create covalent bonds of fluorocarbon radicals with the PMMA surface, which yielded reduced surface power as well as remarkably smooth coating. The fluorine therapy substantially improved biocompatibility.
In researches carried out by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes dental implanted showed a precision price of ± 0.5 D while 97% showed an accuracy rate of ± 2 D. In regards to safety and security, the BSCVA prices had 47 obtaining at the very least 2 lines, and also no eyes lost lines. The overall glare report revealed that many people had few troubles.
According to Mike Landreville, international director for refractive innovations at Bausch & Lomb, the business has no purpose of introducing the NuVita lens into the United States for FDA authorization or for medical use. Instead, the company is establishing an entire brand-new phakic technology for a foldable anterior chamber phakic lens. The new phakic lens will certainly not just exist as a brand-new lens, however as part of a totally brand-new system, totally different from the NuVita line. The new, unrevealed lens system will certainly be of a new product, integrate a new collapsible shipment system and also give a new diagnostic tool for implantation.
According to Mr. Landreville, the business intends to have the new system prepared for clinical use in the United States 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. Worth, Texas) material and has several benefits over various other phakic IOLs such as its foldability, which enables the lens to be put through a cut smaller than 3 mm, along with an angle-fixated, single-piece style and high biocompatibility. The range in between the cornea and the implant additionally drops between 2.96 mm as well as 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 day, greater than 90% of the individuals have 20/40 or far better uncorrected vision at their postoperative check outs. The mean round matching in clients dental implanted so far was– 11.5 D, he claimed, with an outcome of– 0.39 D at 1 month and– 0.8 D at 6 months of residual myopia.
” We see substantial improvement in best-corrected visual acuity, as well as in all but one person the postoperative finest remedied vision is better than the most effective preoperative vision; in a lot of cases, there are 2-, 3- or 4-line boosts in best-corrected visual acuity,” Dr. Maxwell stated. “In the one situation where it had not been much better, it coincided as the preoperative acuity.”
CIBA acquires licenses for IOL
CIBA Vision announced at the AAO meeting that it has acquired 3 licenses from Dr. Baikoff for collapsible phakic former chamber IOL develops to remedy not only nearsightedness as well as hyperopia however also presbyopia.
” We are extremely thrilled about this new innovation,” David Bailey, medical service device president for CIBA, claimed. “We believe that the MemoryLens material combined with these former chamber styles will be a very successful mix.”
That anterior chamber lens campaign enhances another refractive dental implant that was the topic of numerous discussions in the CIBA Vision cubicle– the PRL. This posterior-chamber phakic dental implant is being developed by Medennium Inc. CIBA Vision took a 10% equity stake in Medennium in July as well as currently holds exclusive worldwide advertising and marketing and also distribution civil liberties to the lens, which is currently in phase 2 medical trials.
” We are taking a solid position in phakic IOLs,” Mr. Bailey said, “as well as we’ll be reinforcing that setting with more new technology.”
This is the means to treat myopia, ypermetropia as well as astigmatism (αστιγματισμος ).