January 28th, 2010
Riboflavin treatment has shown great results in some studies in strengthening the cornea of patients with keratoconus. The treatment acts by increasing cross-linking within the cornea stroma with the application of ultraviolet light to the riboflavin solution. In order for the treatment to be effective both the UV light and the riboflavin must be absorbed by the corneal stroma. Above the stroma rests the epithelium, the upper layer of the cornea that sheds throughout the week. Treating the epithelium with riboflavin and UV light is ineffective as it sheds itself regularly. Additionally, the epithelium acts as a barrier to both the UV light and the riboflavin solution.
Studies show that without removal of the epithelium, both the UV light and the riboflavin are highly reduced and the effect of corneal cross-linking is also significantly reduced. Additionally, some surgeons have expressed concern that by not removing the epithelium, the treatment is putting the patient at a higher risk for cataracts or macular damage since the riboflavin is less absorbed by the stroma and often a higher level of UV light is required if the epithelium is not removed.
Most ophthalmologists currently providing riboflavin treatment for corneal cross-linking are currently using an epithelium off method for maximum effectiveness. Removing the epithelium results in a more uncomfortable recovery but maximizes the effectiveness of the treatment.
October 23rd, 2009
In the August 2006, Current Opinion in Ophthalmology, Gregory Wollensak presents his finding for the treatment of progressive keratoconus using collagen crosslinking by the photosensitzer riboflavin and ultraviolet A-light. He summarizes that “biomechanical measurements have shown an impressive increase in corneal rigidity of 328.9% in human corneas after crosslinking.”
He further oncluded that, “The 3 and 5-year results of the Dresden clinical study have shown that in all treated 60 eyes the progression of keratoconus was at least stopped (’freezing’). In 31 eyes there also was a slight reversal and flattening of the keratoconus by up to 2.87 diopters. Best corrected visual acuity improved slightly by 1.4 lines. So far, over 150 keratoconus patients have received crosslinking treatment in Dresden. Laboratory studies have revealed that the maximum effect of the treatment is in the anterior 300 μm of the cornea. As for the corneal endothelium, a cytotoxic level for endothelium was found to be 0.36 mW/cm2 which would be reached in human corneas with a stromal thickness of less than 400 μm.”
In summary, he stated that, “Collagen crosslinking by the photosensitzer riboflavin and ultraviolet A-light is an effective means for stabilizing the cornea in keratoconus. Collagen crosslinking might become the standard therapy for progressive keratoconus in the future diminishing significantly the need for corneal transplantation. Preoperative pachymetry and individual control of the ultraviolet A-irradiance before each treatment are mandatory. The treatment parameters must not be varied.”
Turner EYe Institute continues to maintain itself on the forefront of innovation. For information regarding Keratoconus treatment, including collagen crosslinking, please contact our offices in San Jose, San Leandro, Concord, and San Francisco.
March 12th, 2009
Keratoconus patients have better opportunities than ever for treatments of their condition. Two new technologies have now been combined to offer a substantial benefit for patients with keratoconus. Corneal Collagen Crosslinking with Riboflavin combined with Intacs treatment offers an opportunity to possibly stop the deterioration of the cornea and even reverse it in many cases.
In the past, patients with keratoconus would wear hard contact lenses until those no longer helped. At that point, they would have a corneal transplant. Studies suggest however that early treatment may be beneficial in preventing this decline. Rather than wearing contact lenses until they fail, it is believed that intacs corneal inserts can be an earlier solution. Riboflavin treatment can also be used to improve the strength of the cornea.
November 20th, 2008
Here is an article presented in Ophthalmology Times:
Collagen crosslinking shows promise for keratoconus sill more prospective clinical data needed to characterize risks and benefits
Publish date: Oct 15, 2008
By: Cheryl Guttman
Source: Ophthalmology Times
- Research to date involving stress-strain measurements has shown that the collagen crosslinking procedure causes mechanical stiffening of the cornea.
- Dr. Seiler’s current treatment protocol for collagen crosslinking involves a partial corneal abrasion performed over a diameter of 9 mm.
- According to Dr. Seiler collagen crosslinking using ultraviolet A light and the photosensitizer riboflavin has been effective in stopping the progression of keratoconus in almost all eyes, and it has induced regression in about half of treated eyes based on reductions in keratometry readings. However, more prospective clinical data is needed to characterize its risks and benefits and to establish a list of indications and contraindications for this procedure.
Results achieved with corneal collagen crosslinking for the treatment of keratoconus are very encouraging, although the technique still must be considered investigational due to a lack of sufficient data published in the peer-reviewed literature, said Theo Seiler, MD, PhD.
“In our experience, collagen crosslinking using ultraviolet A light and the photosensitizer riboflavin has been effective in stopping the progression of keratoconus in almost all eyes, and it has induced regression in about half of treated eyes based on reductions in keratometry readings,” said Dr. Seiler, professor and chairman, Department of Ophthalmology, University of Zurich, and medical director, Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland. “However, we clearly need more prospective clinical data to characterize its risks and benefits and to establish a list of indications and contraindications for this procedure.”
Research to date involving stress-strain measurements has shown that the collagen crosslinking procedure causes mechanical stiffening of the cornea. Corneal rigidity, as assessed by Young’s modulus, increased by more than 4-fold after the procedure, Dr. Seiler said.
In addition, experiments performed with porcine corneal buttons show the treatment results in increased resistance of the extracellular matrix to enzymatic digestion compared with native corneal collagen. “The underlying mechanism for this latter effect of the crosslinking procedure is unknown, but it may play a role in the posttreatment reconstruction of the cornea,” he said.
He also said his current treatment protocol for collagen crosslinking involves a partial corneal abrasion performed over a diameter of 9 mm. Then a solution of 0.1% riboflavin in 20% dextran is dropped on the cornea approximately every 3 minutes for 30 minutes. The treated cornea is irradiated for 30 minutes with a 365-nm ultraviolet light source at a distance of 5 cm using an intensity of 3 mW/cm2.
“An alternative technique proposes using topical tetracaine to digest the epithelium and enable diffusion of the riboflavin into the stroma,” Dr. Seiler said. “However, using confocal microscopy, we found there is keratocyte damage to a depth of about 300 to 350 m using our crosslinking technique with corneal abrasion, whereas with the use of tetracaine, normal reflections from keratocyte nuclei can already be seen below the anterior 20 m of stroma. Therefore, it appears there is significantly less free radical formation and crosslinking of collagen fibers using the latter technique.”
He also noted that both the mechanical and biochemical effects of the procedure are very sensitive to the treatment parameters with respect to the concentration of the riboflavin solution used and the duration of application. Therefore, he encouraged that the efficacy of any modified protocol be investigated carefully prior to adoption in clinical use.
To date, Dr. Seiler and colleagues at the Technical University of Dresden, Dresden, Germany, have treated about 700 eyes with collagen crosslinking. Follow-up extending to 4 years shows the benefits are durable. An analysis including 21 patients with bilateral keratoconus who underwent crosslinking in only one eye showed the keratoconus index was increased in the untreated eyes after 1 year and significantly was higher than in the fellow crosslinked eyes.
“Crosslinking was not performed randomly in these patients but rather was used to treat the worse eye,” Dr. Seiler said. “Comparisons in individual patients showed there was a significant difference in the keratoconus index between the treated and untreated eye after 1 year in nearly all patients, and the difference between eyes was highly statistically significant in some cases.”
The safety profile of corneal collagen crosslinking has been favorable as well with very few complications recorded. Epithelial healing was delayed in some eyes and resulted in a subepithelial scar. More recently, in some eyes in which the procedure was repeated, a small scar in the anterior segment occurred that persisted for up to 6 months.
July 3rd, 2008
Turner Eye Institute wishes everyone a happy 4th of July. We would like remind everyone to use protective eyewear where appropriate in using fireworks or other celebrations. Eye safety should be on everyone’s minds when handling pyrotechnics or using fire, such as with grills.
June 26th, 2008
The new Corneal Crosslinking treatment with Riboflavin has shown success since being introduced by Dr. Stephen Turner in Northern California. Recent studies are showing that Riboflavin treatment followed by UV light can improve the cornea with keratoconus.
Patients with keratoconus should consult with a corneal specialist ophthalmologist regarding their condition. The doctor might advise Corneal crosslinking treatment with riboflavin or might suggest intacs. Many surgeons have used both with good results.
Dr. Stephen Turner practices in the San Francisco Bay area and is a corneal specialist who treats patients with keratoconus. He has offices in San Francisco, San Leandro (in the East Bay near Oakland), Concord (near Walnut Creek), and San Jose. Patients interested in discussing their vision needs should contact Turner Eye Institute for an appointment.
March 24th, 2008
Collagen Crosslinking Using Riboflavin and UV Light Exposure for Keratoconus — First IRB Approved Study in India Started at Apollo Hospitals, Hyderabad
Collagen Crosslinking treatment is a new hope for keratoconus patients. This treatment helps arrest the progression of the disease, and the first IRB approved study in India has been initiated at Cornea Clinic, Hyderabad, by Dr Rajesh Fogla, senior corneal surgeon. Keratoconus patients can enquire for eligibility for this treatment.
Hyderabad, India, January 19, 2007 — Keratoconus is a corneal disease affecting 1 in 2000 individuals. The disease usually starts in young adults, and is characterized by progressive thinning and outward protrusion of the cornea. (Cornea is the clear structure in front of the human eye responsible for focusing of rays of light into the eye for a clear image.)
The cornea takes a conical shape, and produces astigmatism due to which the rays of light cannot be focused properly, resulting in deterioration of the quality of vision. In the early stage of keratoconus, vision can often be improved using cylindrical correction in the glasses. However, in later stages most patients require rigid gas permeable lenses for improvement in quality of vision. Intacs are plastic ring segments which can be inserted into the mid-peripheral cornea to produce flattening of the central cornea. This results in reduction of the severity of keratoconus, and improves both vision & contact lens fitting to a certain extent. However it does not affect the progression of keratoconus. It is estimated that almost 21% of keratoconus patients ultimately progress to an advanced stage of disease requiring corneal transplantation surgery to restore corneal architecture and improve eyesight.
Dr Rajesh Fogla, Senior Consultant, Corneal Surgeon at Apollo Hospitals, Hyderabad, India, has special interest in Keratoconus & its management. He has been providing specialized contact lens fitting for keratoconus patients, and also performs deep anterior lamellar keratoplasty (DALK) surgery. Compared to conventional full thickness corneal transplantation surgery, DALK surgery has several advantages. Unlike conventional corneal transplantation surgery wherein a central disc of full thickness cornea is entirely replaced with donor tissue, in lamellar keratoplasty the healthy inner layer of the patient’s cornea is retained and not sacrificed. (This layer called the endothelium is the most vital layer of the cornea responsible for maintaining the corneal clarity). Only the outer 80 -90% of the cornea is replaced with healthy donor tissue.
The other advantage of lamellar keratoplasty, is that as the inner layer is retained, the immune cells of the body do not recognize the outer donor tissue as being foreign. Hence there is no risk of endothelial rejection with lamellar keratoplasty, unlike full thickness graft wherein steroid therapy has to be continued for years to prevent graft rejection episodes. Dr Fogla has been performing deep anterior lamellar keratoplasty since 1998, and currently performs the same in all his patients with advanced keratoconus. He has been conducting instruction courses at various national and international meetings on the same subject.
Dr Fogla, has started performing collagen crosslinking treatment using the photo-sensitizer riboflavin (Vitamin B2) and ultraviolet light (365nm) exposure for keratoconus patients. In extensive experimental studies, researchers have demonstrated a significant increase in corneal rigidity / stiffness after collagen cross-linking using this riboflavin / UVA treatment. The 3 & 5 year results of Dresden clinical study in human eyes has shown arrest of progression of keratoconus in all treated eyes. (Wollensak G. Crosslinking treatment of progressive keratoconus: New Hope. Current Opinion in Ophthalmology 2006; 17: 356 - 360).
Keratoconus patients now have a new hope, a new treatment modality which can arrest the disease progression and thereby prevent the need for surgical intervention in future. Although the procedure does not provide a cure for keratoconus, it certainly can stop its progression and patients can continue using their glasses or contact lenses for improved eyesight. Hence attempt should be made to diagnose keratoconus early enough and stop its progression using collagen crosslinking. Corneal topography can detect keratoconus much before it can be picked up on a routine eye examination. Hence this test should therefore be performed in all cases with high astigmatism, i.e., cylindrical power to detect keratoconus at an early stage. Further ongoing studies will help establish collagen cross-linking treatment as the primary modality of treatment for keratoconus.
November 27th, 2007
Although Dr. Turner has previously been performing Keratoconus Correction in San Jose, Turner Eye Institute has a new location in Campbell, California. Dr. Stephen Turner is well-known throughout California as one of the most experienced Keratoconus surgeons. He is also known for his innovation and excellent results with intacs and other methods of keratoconus correction. Dr. Turner introduced many of todays most successful eye surgery procedures to Northern California, Oakland, San Jose, San Francisco, and Walnut Creek. The advanced Crystalens procedure for improving near vision, the exciting Visian procedure for patients with moderate to high near-sightedness, and the precision of Wavefront LASIK, Intra-Lase, and TF LASIK were all introduced by Dr. Stephen Turner.
The new location in Campbell, CA contains the same advanced technology including the upgraded VISX laser with iris tracking software. San Jose patients can therefore expect the same high level of treatment in Campbell, CA that they had at each of the Turner Eye Institute locations, including San Jose, San Francisco, Walnut Creek, and Oakland. Dr. Turner will perform keratoconus procedures at each of the four locations in Northern California.
Turner Eye Institute performs cataract surgeries and other vision corrective procedures in San Leandro, CA (South of Oakland and north of Fremont). The surgical center provides a sterile environment to provide the highest level of safety for our patients.
September 21st, 2007
Scientists are discovering new biomaterials for use in bones, tissues, and other locations throughout the human body. We are following recent advances in corneal technology with interest.
Currently, one of the best treatments for keratoconus is through the use of intacs to help strengthen and support the cornea. While this is not a cure for keratoconus it has helped many patients with keratoconus to see more clearly and perhaps avoid the worst of this often debiltating condition.
It is likely that future technologies will follow a similar method to intacs in providing a support structure for the cornea that can help withstand the weakening effects of this collagen disorder. It can be expected that newer biomaterials will be developed that are smaller and stronger. Future advances in nanotechnology might build strong support structures within the cornea that can help delay or counteract the effects of keratoconus.
Currently, patients with keratoconus will often be advised that intacs can provide a level of relief and perhaps slow the effects of keratoconus. Some studies have shown that contact lenses might hasten the onset of keratoconus so many surgeons are suggesting that keratoconus patients using contact lenses should undergo intacs treatment before vision is substantially affected.
August 28th, 2007
Beginning October 1st, 2007, Turner Eye Institute and Horizon Vision Centers will relocate the Keratoconus Treatment Center branch in San Jose. The new San Jose Keratoconus Treatment Center will be located at 50 E. Hamilton, Suite 100, Campbell, California. The telephone number is 408-374-2020.
The new Horizon and Turner Eye Institute Keratoconus Treatment San Jose branch is located in a small mall complex inside the two-story white spanish style building that fronts Hamilton Ave.
From Santa Cruz Area:
Head North on CA-17 (signs for San Jose) Take Exit 25 towards Hamilton Ave. Turner Left at creekside Way. Turner Left at E. Hamilton Ave. End at 50 E Hamilton Ave.
From San Francisco/Peninsula
Take I-280 South towards San Jose. Merge onto CA-17 South towards Santa Cruz. Take the Hamilton Exit - Exit 25. Keep right at the fork to go on E. Hamilton Ave. End at 50 E. Hamilton Ave.
From the East Bay
Take the I-880 South towards San Jose. I-880 South becomes CA-17 South. Take the Hamilton Ave exit - Exit 25. Keep Right at the fork to go on E. Hamilton. End at 50 E. Hamilton Ave.
Welcome everyone to our new location in San Jose. The San Jose Keratoconus Treatment center in Campbell will continue to provide the same advanced treatments and excellent service as all our Keratoconus Treatment locations throughout the San Francisco Bay Area, including Oakland, San Francisco, and Walnut Creek.