Emerging modern technology in the locations of corneal ring sectors, holmium laser thermokeratoplasty (LTK) and also phakic IOLs is providing new alternatives for patients experiencing 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 research of options to penetrating keratoplasty for individuals with keratoconus. Of 23 eyes in 20 individuals, 60% accomplished a best-corrected visual acuity of 20/40 or better. The mean postoperative keratometry was decreased by 3 D.
Daniel S. Durrie, MD, discussed Dr. Colin’s paper, which suggests an option that reinforces the currently compromised 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 lot of feeling, Dr. Durrie informed Primary Care Optometry Information.
” For many years, we’ve considered various other choices to corneal transplants for these patients, as well as some procedures 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 a patient population in which we understand the cornea is currently slim as well as weak,” Dr. Durrie stated.
Due to the fact that the keratoconic eye has a bulge in the cornea, Dr. Durrie claimed, placing the Intacs put in the perimeter of the cornea will certainly squash the corneal facility. This not just lowers the level of myopia, however reinforces the facility bulge, he claimed. The preferred end result is to delay a corneal transplant for as long as feasible.
While the information that Dr. Colin offered program that the treatment is rather secure, stated Dr. Durrie, the lengthiest term information readily available are just 2 years. “Considering the patterns in the 3-month, 6-month as well as 1-year data, it shows up that all clients benefited from the procedure, but we can’t claim that it stopped the keratoconus for longer than that till additional data are collected,” he said. “Although I remain to do this treatment on isolated cases, I tell patients we do not know the lasting results as well as we do not know whether it will certainly slow down, accelerate or have no result on the normal course of keratoconus.
” The benefit of this treatment is, if it doesn’t function, you can take the Intacs out and also have actually not deteriorated the cornea,” he continued. “If the individual does need to take place to a corneal transplant, the inserts can be taken out and not interfere with typical transplant therapy. As a result of the modification fit of the keratoconic cornea, at some point, patients end up being get in touch with lens intolerant, as well as it’s important to understand that there is a different to be checked out for these people apart from just referring them for a corneal transplant.”
Experts ought to be sure that people recognize that the procedure is not refractive surgical treatment as well as will certainly not always remedy their nearsightedness, claimed Dr. Durrie. “I have patients on whom I have actually executed this treatment who have actually seen 20/40 without glasses, which would certainly be an outstanding result after a corneal transplant, however they’re still questioning why their pals that have actually had Intacs implanted can see 20/20 when they can’t,” he stated. “That’s why these people need to be informed that this isn’t something that maintains them from wearing glasses. It keeps them from requiring a corneal transplant.”
Hyperopic adjustment with LTK
picture– Post-LTK: The pulses are applied in eight places, one at the 6-mm area and also the various other at the 7-mm area.
Professional research studies have actually shown laser thermokeratoplasty (LTK) to be an effective approach of fixing a patient’s hyperopia, and it may also hold assurance for treating presbyopia and overcorrected myopia after LASIK or PRK, said David J. Conway, OD, supervisor of refractive surgery for Harvard Vanguard Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK strategy and its outcomes with hyperopia using the Hyperion laser (Daybreak Technologies International, Fremont, Calif.) at the International Society of Refractive Surgical treatment’s Summertime Globe Refractive Surgery Symposium 2000. Dr. Conway was not involved in any kind of Fda (FDA) research study; his ISRS discussion was based on information from the Sunup FDA investigations and also talks he went to.
When treating an individual for hyperopia, the specialist needs to worry the brevity of the treatment, he stated. “You need to communicate to the patient that this is just a temporary change in his/her hyperopic standing,” he said. “There suffices regression with this technique that the FDA felt it required to make mention of this.”
Any type of treatment for the correction of hyperopia might demand retreatment in time; this is not distinct to LTK, said Sandra Belmont, MD, supervisor of the laser vision center at the Cornell Weill Medical Center in New York City City. “Hyperopia enhances as you age,” she said. “We have people 3 years out who are stable, so I’m really happy with the outcomes.”
Dr. Belmont educates patients of this possibility, yet none of them have changed their minds. She claimed that if retreatment were needed, clients did not mind since the procedure is quick, and also creating a flap, which can result in problems, is not necessary.
The LTK procedure
picture– Stability: One scientist has people that are still stable 3 years post-LTK.
The treatment, Dr. Conway said, takes 3 seconds to perform. 7 pulses are used in 8 places, two times back to back, one at the 6-mm area and the various other at the 7-mm area. 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 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 said. “In comparing preop to 24 months later, there was no loss of BSCVA and also a bit of gain. We know that myopes as well as hyperopes are really various. Luckily, the resistance of hyperopes is really handy in making their complete satisfaction degree extremely high.”
Prior to the treatment, people receive 3 consecutive administrations of topical proparacaine at 3-minute intervals. Difficulties were marginal, Dr. Conway noted.
” Clients are generally taken care of from a comfort viewpoint, purely with non-prescription anesthetics to obtain them with the very first hrs of healing,” he claimed. “Since you’re working on the corneal surface area, FDA private investigators reported a little bit of foreign-body sensation, which dissipates with time very perfectly.”
Dr. Conway said that, while the person’s skill degree remains rather steady, some regression appears as the hyperopia enhances gradually. “There will certainly be a tiny yet considerable regression in these people; it’s just a matter of whether it goes to a reduced enough degree to validate the person’s expense as well as experience of undergoing this strategy,” he said. “By contrasting your cycloplegic to your manifest refraction, you can inform whether it’s latent hyperopia or otherwise.”
A patient’s age consider to the length of time the impact of LTK may last, said Dr. Conway. “A 50-year-old patient will certainly experience a little bit more impact than a 40-year-old client, maybe because of a bit much more dry skin or the collagen standing of the cornea,” he said.
An off-label indication of LTK is the therapy of presbyopia, stated Dr. Belmont. Individuals who are plano and presbyopic might be treated with LTK to achieve monovision, she stated. “Today, their analysis vision enters into focus,” she claimed. “They get their outcomes right away, as well as they’re truly pleased keeping that.”
Patients who have been treated for presbyopia commonly will run into the very same level of regression as hyperopes, Dr. Belmont noted. “Presbyopia raises as you age, as does hyperopia,” she claimed. “People understand that this treatment will certainly need to be enhanced as their aging necessitates a boost in the power they’ll need to review. They’re happy as long as you tell them in advance. I expect this as being the treatment to deal with farsightedness as well as presbyopia.”
The size of time required for presbyopic treatment is the same when it comes to that of hyperopia, but the degree of energy that is related to the eye is differed, she claimed.
The treatment may likewise prove to be a legitimate choice for boosting nearsighted patients that have actually been overcorrected with LASIK or PRK, claimed Dr. Conway. “This advantages a lot of consideration, because you don’t need to eliminate any type of cells,” he said. “In addition, Daybreak is sending for authorization removal of presbyopia, making clients nearsighted in a monovision fashion. So, I believe this will become a relatively preferred and also common alternative in this patient populace, and also we’ll see the number of even more surgeons make a decision to accept it.”
LTK is accepted for approximately +2.5 D, claimed Dr. Belmont, as well as is currently undergoing trials for therapy approximately +5.6 D.
Refractec’s conductive keratoplasty
Initial clinical trials recommend that conductive keratoplasty (CK) utilizing Refractec’s (Irvine, Calif.) radiofrequency method is possibly secure and reliable for remedying reduced to modest quantities of hyperopia, according to Penny A. Asbell, MD, who presented clinical trial information in Miami at the International Culture of Refractive Surgery meeting. “Very early outcomes with our information out to year recommend that we obtain terrific visual acuity, very good security and actually no unfavorable events, such as loss of vision,” said Dr. Asbell.
CK heats the stromal tissue with an electrical existing, shrinks the collagen as well as steepens the central cornea, Dr. Asbell explained. A high-frequency present is applied straight into the peripheral corneal stroma via a distribution suggestion placed at eight or even more therapy factors. The launch of radiofrequency energy warms the surrounding collagen to a homogenous temperature level of 65 ° C and generates a cylindrical footprint 500 µm deep vs. a shallower, cone-shaped footprint made with the LTK technique. A cycle of CK-treated places cinches the cornea and also raises its curvature to decrease hyperopia.
” The change appears to be irreversible, and I assume one of the factors that’s true is that the therapy is delivered straight to the stroma,” claimed Dr. Asbell. “That’s where you desire the impact– out the endothelium, not on the epithelium. It’s an extremely simple surgical method. It’s a non-laser strategy, as well as it includes another dimension to what we currently can use for refractive surgical procedure– it is a cost-effective treatment,” she added.
CK is consistent
An additional vital problem, Dr. Asbell pointed out, is that CK is a consistent therapy. “The treatment dimension and the zone impact in the stroma are consistent from therapy spot to therapy place,” she said. “One of the essential problems to keep in mind is that the temperature we get with the CK treatment is constantly 65 ° and also the imprint you make within the outer corneal stroma is always the same: 100 µm wide and 500 µm deep within the corneal stroma.”
Dr. Asbell is an investigator in the FDA scientific trial of CK. Fellow detectives at various 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 people on whom Dr. Asbell reported, the typical age was 55, although, she said, there is a relatively large range of age among the test’s participants. To get the test, she described, clients needed to have uncorrected visual acuity of at least 20/40 or worse as well as poor near vision also– basic for a hyperope. “We are fixing from 1 D to 4 D of hyperopia, with little or no astigmatism,” Dr. Asbell reported.
She stressed the rate as well as simplicity of the procedure. “This treatment takes 5 mins per eye. It is an extremely short procedure; you remain in and also out very quickly,” she stated. “It is a procedure, but an extremely easy one. It does not need a skilled service technician [to help] It does not also need an autoclave. The pointer, which is about the width of a hair, is non reusable.”
Dr. Asbell described the CK nomogram because of this: “The therapy is either at 6 mm, 7 mm or 8 mm. You make a mark on the cornea [showing the dimension of the treatment zone] The degree of hyperopia you are remedying identifies the variety of treatment marks on the cornea. Each one coincides– the same quantity of power and the exact same depth within the stroma in each spot,” she claimed.
Results show up stable
Of the individuals on whom Dr. Asbell reported, 61% attained uncorrected visual acuity of 20/20 or 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 92% were 20/40 or much better. “Our outcomes look good and secure. These are very pleased people,” stated Dr. Asbell. “They in fact can return to function immediately or certainly the next day if they so select. No one takes discomfort medications.”
Safety and security variables were “basically no,” Dr. Asbell reported. “There was no loss of vision as well as no corneal edema,” she stated. “I believe this is mosting likely to be a procedure and a maker that’s mosting likely to be easy for us to own and also to utilize as well as a superb method to deal with hyperopia postop LASIK or to retouch a postop cataract or corneal transplant,” she claimed. “I believe it’s mosting likely to have a lot of versatility in terms of its uses for fixing hyperopia and perhaps astigmatism.”
Broadened clinical trials of LAPR
SurgiLight Inc. (Orlando, Fla.) has actually expanded its scientific trial researches of laser presbyopia turnaround (LAPR) using its IR-laser in Venezuela, Argentina, Brazil, the Bahamas and Japan. Also, the firm has actually scheduled setup of the IR-laser in some European countries.
SurgiLight has actually sent 4 documents to the American Culture of Cataract as well as Refractive Surgery for the May 2001 conference, where greater than 500 cases of LAPR will be presented by eye doctors from numerous countries making use of the firm’s IR laser.
The company is in the procedure of acquiring CE-Mark qualification and selecting different international representatives. It intends to submit added 510K applications based on certain clearances obtained from Premier Laser Systems. SurgiLight anticipates to charge an aristocracy charge of $500 per individual to specialists who use the business’s IR-3000 system in the USA and Europe.
B&L NuVita phakic IOL
The 3rd generation of George Baikoff, MD’s, anterior 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 layout is an angle-fixated, single-piece lens, with a meniscus optical form and also a PMMA surface area. The total optical diameter is 5 mm as well as the total 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 upgraded from the previous version to reduce refracted glow, pressure in the angle as well as far better clearance of the iris and also all-natural lens. Also, the haptics were upgraded to get rid of iris retraction. The haptics were made more adaptable and, consequently, resulted in less pupil ovalization.
In its 2nd generation, the fluorine plasma treatment was added to the manufacturing procedure to produce covalent bonds of fluorocarbon radicals with the PMMA surface area, which generated reduced surface energy and exceptionally smooth coating. The fluorine therapy greatly improved biocompatibility.
In studies performed by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes dental implanted revealed an accuracy price of ± 0.5 D while 97% revealed an accuracy price of ± 2 D. In terms of safety and security, the BSCVA rates had 47 obtaining at least 2 lines, and no eyes shed lines. The general glare record revealed that a lot of individuals had couple of problems.
According to Mike Landreville, worldwide director for refractive innovations at Bausch & Lomb, the company has no intention of introducing the NuVita lens into the United States for FDA approval or for scientific usage. Instead, the company is establishing an entire new phakic technology for a foldable anterior chamber phakic lens. The new phakic lens will certainly not just exist as a new lens, however as part of a completely brand-new system, totally different from the NuVita line. The new, unrevealed lens system will certainly be of a brand-new material, integrate a new collapsible delivery system and supply a brand-new analysis tool for implantation.
According to Mr. Landreville, the company prepares to have the brand-new system all set for clinical use in the United States by this year.
Alcon phakic IOL
A brand-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 and also has several advantages over various other phakic IOLs such as its foldability, which permits the lens to be inserted through a cut smaller sized than 3 mm, in addition to an angle-fixated, single-piece design as well as high biocompatibility. The range between the cornea and also the implant additionally falls in between 2.96 mm and also 3.35 mm, a bigger range than with a few other lenses, he claimed.
Dr. Maxwell reported that of the 10 implants that have been carried out to day, more than 90% of the clients have 20/40 or better uncorrected vision at their postoperative gos to. The mean round matching in people dental implanted thus far was– 11.5 D, he stated, with a result of– 0.39 D at 1 month as well as– 0.8 D at 6 months of recurring myopia.
” We see significant enhancement in best-corrected visual acuity, as well as in all but one patient the postoperative ideal dealt with vision is better than the best preoperative vision; in many cases, there are 2-, 3- or 4-line rises in best-corrected visual acuity,” Dr. Maxwell said. “In the one situation where it wasn’t much better, it coincided as the preoperative acuity.”
CIBA acquires licenses for IOL
CIBA Vision revealed at the AAO meeting that it has acquired three licenses from Dr. Baikoff for collapsible phakic former chamber IOL develops to deal with not only nearsightedness and also hyperopia yet also presbyopia.
” We are very excited regarding this brand-new modern technology,” David Bailey, surgical company system head of state for CIBA, claimed. “We think that the MemoryLens product incorporated with these anterior chamber layouts will be a very successful mix.”
That anterior chamber lens effort enhances an additional refractive dental implant that was the subject of several presentations 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 stake in Medennium in July as well as now holds unique globally advertising and marketing and also circulation civil liberties to the lens, which is currently in stage 2 medical tests.
” We are taking a strong placement in phakic IOLs,” Mr. Bailey claimed, “as well as we’ll be enhancing that placement with even more brand-new innovation.”
This is the way to deal with nearsightedness, ypermetropia and also astigmatism (μυωπια ).