Emerging modern technology in the locations of corneal ring sectors, holmium laser thermokeratoplasty (LTK) as well as phakic IOLs is giving brand-new options for clients experiencing keratoconus, nearsightedness, hyperopia and presbyopia.
Intacs for keratoconus
At the American Academy of Ophthalmology (AAO) meeting in October 2000, Joseph Colin, MD, offered a research of options to passing through keratoplasty for clients with keratoconus. Of 23 eyes in 20 patients, 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, talked about Dr. Colin’s paper, which recommends an alternative that reinforces the currently weakened cornea rather than 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 informed Health care Optometry News.
” For several years, we have actually looked at other alternatives to corneal transplants for these people, as well as some procedures such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have been attempted in the past, but they eliminate part of the cornea in a patient populace in which we know the cornea is currently slim and weak,” Dr. Durrie claimed.
Because the keratoconic eye has a bulge in the cornea, Dr. Durrie stated, putting the Intacs put in the periphery of the cornea will certainly squash the corneal facility. This not just reduces the level of nearsightedness, but reinforces the facility bulge, he stated. The preferred end result is to postpone a corneal transplant for as long as feasible.
While the data that Dr. Colin provided show that the treatment is quite secure, said Dr. Durrie, the lengthiest term information available are just 2 years. “Considering the trends in the 3-month, 6-month as well as 1-year information, it shows up that all patients took advantage of the treatment, but we can’t say that it quit the keratoconus for longer than that until additional information are gathered,” he said. “Although I remain to do this procedure on separated cases, I tell individuals we do not know the long-term impacts and also we do not recognize whether it will reduce, quicken or have no effect on the normal course of keratoconus.
” The benefit of this procedure is, if it does not work, you can take the Intacs out and have not deteriorated the cornea,” he continued. “If the client does require to go on to a corneal transplant, the inserts can be taken out and not interfere with standard transplant treatment. Because of the modification fit of the keratoconic cornea, eventually, clients end up being call lens intolerant, as well as it is essential to know that there is an alternate to be explored for these patients besides simply referring them for a corneal transplant.”
Practitioners must make certain that patients comprehend that the procedure is not refractive surgical procedure as well as will certainly not necessarily fix their nearsightedness, claimed Dr. Durrie. “I have patients on whom I have actually performed this treatment who have actually seen 20/40 without glasses, which would be a superior result after a corneal transplant, yet they’re still asking yourself why their friends who have actually had Intacs implanted can see 20/20 when they can’t,” he said. “That’s why these individuals require to be informed that this isn’t something that maintains them from wearing glasses. It maintains them from requiring a corneal transplant.”
Hyperopic change with LTK
photo– Post-LTK: The pulses are used in 8 places, one at the 6-mm area and also the various other at the 7-mm area.
Scientific studies have shown laser thermokeratoplasty (LTK) to be an effective technique of correcting a client’s hyperopia, and it might also hold promise for treating presbyopia as well as overcorrected nearsightedness after LASIK or PRK, claimed David J. Conway, OD, supervisor of refractive surgical treatment for Harvard Vanguard Medical Associates in Somerville, Mass
. Dr. Conway reported on the LTK method as well as its results with hyperopia making use of the Hyperion laser (Dawn Technologies International, Fremont, Calif.) at the International Society of Refractive Surgical treatment’s Summer World Refractive Surgery Seminar 2000. Dr. Conway was not involved in any Food and Drug Administration (FDA) research; his ISRS discussion was based upon information from the Sunup FDA investigations and talks he attended.
When treating an individual for hyperopia, the specialist requires to stress the brevity of the treatment, he said. “You need to convey to the person that this is only a momentary change in his or her hyperopic condition,” he stated. “There suffices regression with this method that the FDA felt it needed to make mention of this.”
Any type of treatment for the adjustment of hyperopia might demand retreatment over time; this is not distinct 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 stated. “We have individuals 3 years out that are secure, so I’m very delighted with the outcomes.”
Dr. Belmont informs people of this possibility, however none of them have actually altered their minds. She said that if retreatment were required, patients did incline since the treatment is quick, and also developing a flap, which can result in complications, is not required.
The LTK procedure
photo– Stability: One scientist has people who are still stable 3 years post-LTK.
The procedure, Dr. Conway claimed, takes 3 secs to execute. 7 pulses are applied in eight places, two times back to back, one at the 6-mm area and also the various other at the 7-mm area. The FDA study reported that the 612 eyes in 379 individuals, 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 skill were attributable to the LTK,” he said. “In contrasting preop to 24 months later on, there was no loss of BSCVA and also a bit of gain. We know that myopes and also hyperopes are very various. Fortunately, the resistance of hyperopes is very practical in making their fulfillment degree very high.”
Prior to the procedure, clients get three successive managements of topical proparacaine at 3-minute intervals. Problems were very little, Dr. Conway noted.
” Individuals are normally managed from a convenience point ofview, strictly with over the counter anesthetics to obtain them through the first hrs of healing,” he claimed. “Because you’re working on the corneal surface, FDA private investigators reported a bit of foreign-body sensation, which dissipates with time extremely well.”
Regression over time
Dr. Conway stated that, while the client’s acuity degree stays relatively secure, some regression appears as the hyperopia enhances in time. “There will be a small yet significant regression in these patients; it’s just an issue of whether it goes to a reduced adequate level to validate the patient’s expense as well as experience of undertaking this strategy,” he said. “By comparing your cycloplegic to your reveal refraction, you can tell whether it’s latent hyperopia or not.”
A patient’s age consider to how much time the effect of LTK may last, stated Dr. Conway. “A 50-year-old patient will certainly experience a bit much more effect than a 40-year-old patient, perhaps due to a bit a lot more dry skin or the collagen condition of the cornea,” he stated.
An off-label indication of LTK is the therapy of presbyopia, stated Dr. Belmont. Patients that are plano as well as presbyopic may be treated with LTK to achieve monovision, she stated. “Right away, their reading vision comes into emphasis,” she claimed. “They obtain their results quickly, and they’re actually delighted with that.”
People that have actually been treated for presbyopia usually will experience the very same degree 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 demands a rise in the power they’ll require to review. They enjoy as long as you tell them beforehand. I anticipate this as being the procedure to treat farsightedness as well as presbyopia.”
The size of time required for presbyopic treatment coincides when it comes to that of hyperopia, yet the level of power that is put on the eye is varied, she stated.
The procedure might likewise show to be a legitimate choice for boosting nearsighted people that have been overcorrected with LASIK or PRK, claimed Dr. Conway. “This benefits a lot of factor to consider, because you do not have to eliminate any type of tissue,” he stated. “In addition, Sunrise is submitting for approval remediation of presbyopia, making individuals short-sighted in a monovision fashion. So, I believe this will come to be a rather preferred and typical option in this patient populace, as well as we’ll see how many even more surgeons choose to embrace it.”
LTK is authorized for approximately +2.5 D, said Dr. Belmont, and also is presently going through trials for therapy approximately +5.6 D.
Refractec’s conductive keratoplasty
Initial scientific tests recommend that conductive keratoplasty (CK) making use of Refractec’s (Irvine, Calif.) radiofrequency technique is most likely risk-free and reliable for fixing reduced to moderate amounts of hyperopia, according to Penny A. Asbell, MD, that presented scientific test information in Miami at the International Society of Refractive Surgical procedure meeting. “Very early outcomes with our information bent on year recommend that we obtain excellent visual acuity, great stability as well as really no adverse occasions, such as loss of vision,” stated Dr. Asbell.
CK warms the stromal tissue with an electrical existing, reduces the collagen as well as steepens the main cornea, Dr. Asbell discussed. A high-frequency existing is used directly into the peripheral corneal stroma through a delivery suggestion inserted at eight or even more therapy points. The launch of radiofrequency energy heats up the bordering collagen to an identical temperature level of 65 ° C and produces a round footprint 500 µm deep vs. a shallower, cone-shaped impact made with the LTK method. A full circle of CK-treated places cinches the cornea as well as enhances its curvature to decrease hyperopia.
” The modification seems to be permanent, as well as I believe among the reasons that’s true is that the therapy is provided straight to the stroma,” said Dr. Asbell. “That’s where you want the impact– not on the endothelium, not on the epithelium. It’s an extremely easy medical method. It’s a non-laser method, and also it adds another dimension to what we currently can offer for refractive surgical treatment– it is a cost-effective procedure,” she included.
An additional vital issue, Dr. Asbell explained, is that CK is a constant treatment. “The therapy size and the area impact in the stroma correspond from therapy spot to therapy area,” she stated. “Among the vital concerns to bear in mind is that the temperature we get with the CK treatment is always 65 ° and the imprint you make within the peripheral corneal stroma is always the same: 100 µm vast as well as 500 µm deep within the corneal stroma.”
Dr. Asbell is a detective in the FDA scientific test of CK. Fellow detectives at other websites include Marguerite McDonald, MD; Robert K. Maloney, MD; Jonathan Davidorf, MD; Peter Hersh, MD; and Edward E. Manche, MD
. Of the 54 clients on whom Dr. Asbell reported, the typical age was 55, although, she said, there is a rather variety of age among the test’s individuals. To receive the test, she clarified, people had to have uncorrected visual acuity of a minimum of 20/40 or even worse and bad 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 speed and simplicity of the treatment. “This procedure takes 5 mins per eye. It is a really brief treatment; you remain in and out very rapidly,” she stated. “It is a surgical procedure, yet an extremely easy one. It does not need a skilled specialist [to aid] It does not also require an autoclave. The tip, which is about the size of a hair, is non reusable.”
Dr. Asbell defined the CK nomogram therefore: “The treatment is either at 6 mm, 7 mm or 8 mm. You make a mark on the cornea [indicating the dimension of the therapy area] The degree of hyperopia you are fixing establishes the variety of treatment marks on the cornea. Every one is the same– the very same quantity of power and the exact same depth within the stroma in each spot,” she claimed.
Outcomes show up stable
Of the individuals on whom Dr. Asbell reported, 61% accomplished uncorrected visual acuity of 20/20 or much better 6 months postoperatively and also 96% were 20/40 or better at the 6-month mark. One year postoperatively, 62% were 20/20 or much better, and also 92% were 20/40 or much better. “Our results look good and also steady. These are really happy clients,” said Dr. Asbell. “They in fact can return to function promptly or certainly the following day if they so choose. No person takes pain medications.”
Safety and security variables were “primarily absolutely no,” Dr. Asbell reported. “There was no loss of vision and also no corneal edema,” she claimed. “I think this is mosting likely to be a procedure and a machine that’s going to be very easy for us to own and also to use and an excellent method to fix hyperopia postop LASIK or to repair a postop cataract or corneal transplant,” she stated. “I think it’s going to have a lot of flexibility in regards to its usages for fixing hyperopia as well as perhaps astigmatism.”
Increased professional trials of LAPR
SurgiLight Inc. (Orlando, Fla.) has actually broadened its scientific trial studies of laser presbyopia turnaround (LAPR) using its IR-laser in Venezuela, Argentina, Brazil, the Bahamas and Japan. Also, the firm has actually set up installment of the IR-laser in some European countries.
SurgiLight has sent 4 papers to the American Society of Cataract as well as Refractive Surgical Treatment for the May 2001 meeting, where more than 500 instances of LAPR will certainly exist by ophthalmologists from various countries using the firm’s IR laser.
The business is in the procedure of acquiring CE-Mark accreditation and choosing numerous worldwide suppliers. It intends to send extra 510K applications based upon specific clearances acquired from Premier Laser Systems. SurgiLight anticipates to bill a nobility fee of $500 per individual to doctors that make use of the business’s IR-3000 system in the United States and Europe.
B&L NuVita phakic IOL
The 3rd 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 ranging from 7 D to 20 D. The style is an angle-fixated, single-piece lens, with a crescent optical shape and also a PMMA surface. The total optical diameter is 5 mm and also the total length of the NuVita ranges from 12 mm to 13.5 mm in 0.5-mm increments.
The optic, loophole and footplate were all revamped from the previous variation to reduce refracted glow, pressure in the angle and also much better clearance of the iris and natural lens. Also, the haptics were upgraded to remove iris retraction. The haptics were made more adaptable and, as a result, caused much less pupil ovalization.
In its second generation, the fluorine plasma treatment was included in the manufacturing procedure to produce covalent bonds of fluorocarbon radicals with the PMMA surface area, which yielded reduced surface energy and also incredibly smooth finish. The fluorine therapy greatly enhanced biocompatibility.
In research studies performed by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes dental implanted showed a precision rate of ± 0.5 D while 97% revealed a precision rate of ± 2 D. In terms of safety and security, the BSCVA prices had 47 getting at the very least two lines, as well as no eyes shed lines. The total glow report showed that many clients had few issues.
According to Mike Landreville, international supervisor for refractive modern technologies at Bausch & Lomb, the business has no objective of presenting the NuVita lens right into the United States for FDA approval or for medical use. Instead, the firm 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 new lens, however as part of a totally brand-new system, totally different from the NuVita line. The brand-new, unrevealed lens system will be of a brand-new product, incorporate a brand-new foldable shipment system and also give a new diagnostic tool for implantation.
According to Mr. Landreville, the business prepares to have the brand-new system all set 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 various other phakic IOLs such as its foldability, which allows the lens to be inserted via a cut smaller sized than 3 mm, along with an angle-fixated, single-piece design as well as high biocompatibility. The range in between the cornea as well as the dental implant likewise falls in between 2.96 mm and 3.35 mm, a larger distance than with some other lenses, he stated.
Dr. Maxwell reported that of the 10 implants that have been carried out to date, more than 90% of the people have 20/40 or much better uncorrected vision at their postoperative brows through. The mean spherical equivalent in clients implanted thus far was– 11.5 D, he claimed, 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, as well as in all yet one person the postoperative finest remedied vision is better than the most effective preoperative vision; in many cases, there are 2-, 3- or 4-line boosts in best-corrected visual acuity,” Dr. Maxwell stated. “In the one case where it had not been much better, it was the same as the preoperative skill.”
CIBA gets patents for IOL
CIBA Vision revealed at the AAO meeting that it has acquired three licenses from Dr. Baikoff for foldable phakic former chamber IOL designs to deal with not just nearsightedness and hyperopia yet likewise presbyopia.
” We are really excited regarding this brand-new innovation,” David Bailey, medical service device head of state for CIBA, said. “We assume that the MemoryLens material combined with these former chamber designs will be a very successful combination.”
That anterior chamber lens effort matches one more refractive implant that was the subject of several discussions 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 as well as currently holds unique around the world advertising and marketing as well as 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 (υπερμετρωπια ).