The SynergEyes® KC Hybrid Contact Lens for Keratoconus

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"As for the race itself, what a difference training makes. This time around I ran nearly 900 training miles (vs. 500 leading up to the San Diego marathon), logged three 20-milers (vs. one 20-miler last time), and read, read, and read some more about running. So I actually knew what I was doing and was well prepared for it."

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Ultraviolet A/Riboflavin Corneal Cross-linking for Infectious Keratitis Associated with Corneal Melts

Hans Peter Iseli, MD, Michael A. Thiel, MD, PhD, Farhad Hafezi, MD, PhD, Juergen Kampmeier, MD, and Theo Seiler, MD, PhD. 

Purpose: To evaluate the efficacy of ultraviolet-corneal crosslinking (CXL) for treating infectious melting keratitis.

Methods: Five patients with infectious keratitis associated with corneal melting were treated with CXL at the outpatient departments of the Institut fur Refraktive und Ophthalmo–Chirurgie and the eye hospital at the University of Zurich. CXL was performed when the infection did not respond to systemic and topical antibiotic therapy. Follow-up after cross-linking ranged from 1 to 9 months.

Results: In all cases, the progression of corneal melting was halted after CXL treatment. Emergency keratoplasty was not necessary in any of the 5 cases presented.

Conclusions: CXL is a promising option for treating patients with therapy refractory infectious keratitis to avoid emergency keratoplasty.

Anpassung formstabiler Kontaktlinsen nach Kollagenvernetzung bei Keratokonus

Carsten Avermann, Markus Kohlhaas

Der Keratokonus führt als erworbene zumeist progressive bilaterale zentrale oder parazentrale Keratektasie durch seinen hohen irregulären Astigmatismus oder durch stromale Hornhautnarben zu einer deutlichen Visusreduktion. In mehr als 20% der Patienten ist eine Visusrehabilitation in einem fortgeschrittenen Stadium nur noch durch eine perforierende bzw. eine tiefe lamelläre Keratoplastik möglich.

Die Quervernetzung der stromalen Kollagenfibrillen mittels Riboflavin und UV-A Bestrahlung (Hornhautvernetzung) scheint hierbei eine neue Therapieoption zur Vermeidung einer weiteren Progression mit konsekutivem signifikanten Visusverlust darzustellen.

Die Quervernetzung der Kollagenfibrillen durch Riboflavin und UVA Bestrahlung modifiziert die biomechanischen Eigenschaften der Hornhaut und führt hierdurch zu einer Verfestigung insbesondere der oberen 200-250 µm. Tiefer gelegene Strukturen werden nicht geschädigt. Die einfache Durchführung wie die geringen Behandlungskosten avisieren die Methode zu einer viel versprechenden Therapieoption insbesondere in Fällen einer zwar nachgewiesenen Progression jedoch bei noch akzeptabler Visussituation. Die Zahl der zur Visusrehabilitation notwendigen Keratoplastiken könnte hierdurch deutlich reduziert werden.

By Our International Scientific News Correspondent

 Jenny Deva MD

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Equal To The Task: The International Congress of Corneal Cross Linking

December 5- 6th, 2008

 The 4th International CXL Congress - The Westin Bellevue Hotel, Dresden, Germany

The strength of the International Congress of Corneal Cross Linking comes primarily from the strength of its people - the organizers and delegates - which made the Congress a outstanding success.

We could see this immensely, and it is also why, long before investing in anything else, from the beginning Keratoconus members started investing in it's people, the finest in the world. Experts with a truly international profile, many of them fluent in many languages. Experts highly prepared to understand the mysteries behind our eye condition, to ultimately eliminate Keratoconus as a health issue internationally.

We give our thanks to the congress organizers, and the delegates that came from all over the world who made this congress a unforgettable historical event. With it also being held for the first time in Dresden, Germany, the place where Corneal Crosslinking (the first ever treatment for Keratoconus) was invented, this made for a congress which was very uniquely memorable.

It was clear for all, the delegates at the congress are "Equal To The Task" to eliminate Keratoconus as a health Issue. More than 269 delegates of high standards in all from 41 countries. World-class Scientists, Internationally renowned Professors, Ophthalmologists, Vision Investigators, Visual Researchers, it was the United Nations for the Cornea !

Thanks to their will and talent, the International Congress of Corneal Cross Linking has managed to put together a wide array of scientific exchange for delegates worldwide. A true boundless solution to discuss and communicate about Keratoconus treatments and technologies in a scientific information sharing atmosphere, which turn the International Congress of Corneal Cross Linking into a worldwide leader in the vision community.

They are a great team, no doubt. But what makes them really big it is simply one thing, their huge ambition to give patients the best possible out-comes. With the highest strictness, discipline, and creativity with Science and Technology.

Thanks to you all.

  Safety, Quality & Teamwork

Corneal Collagen Crosslinking with Riboflavin and Ultraviolet A to Treat Induced Keratectasia after Laser  in Situ Keratomileusis

Purpose: To determine whether riboflavin and ultraviolet-A (UVA) corneal crosslinking can be used as an alternative therapy to prevent the progression of keratectasia.

Setting: Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland, and a private clinic, Athens, Greece.

Methods: Corneal crosslinking was performed in 10 patients with formerly undiagnosed forme fruste keratoconus or pellucid marginal corneal degeneration who had laser in situ keratomileusis (LASIK) for myopic astigmatism and subsequently developed iatrogenic keratectasia. Surgery was
performed in 1 eye per patient.

Results: Crosslinking induced by riboflavin and UVA arrested and/or partially reversed keratectasia over a postoperative follow-up of up to 25 months as demonstrated by preoperative and postoperative corneal topography and a reduction in maximum keratometric readings.

Conclusion: Riboflavin–UVA corneal crosslinking increased the biomechanical stability of the cornea and may thus be a therapeutic means to arrest and partially reverse the progression of LASIK-induced iatrogenic keratectasia.

Collagen Crosslinking with Riboflavin and UVA-light in Keratoconus

Kohlhaas M.

Klinik für Augenheilkunde, St. Johannes-Hospital Dortmund, Johannesstrasse 9-17, 44137, Dortmund, Deutschland.

Reduced corneal mechanical stability in keratoconus and similar corneal diseases can be treated by photooxidative crosslinking of the corneal collagen. This method is currently undergoing clinical evaluation worldwide. To achieve high absorption of the irradiation energy in the cornea, riboflavin at a concentration of 0.1% and UVA light at a wavelength of 370 nm corresponding to the relative maximum of absorption of riboflavin (vitamin B2) is used. These therapeutic parameters were experimentally tested and have been proven clinically. Current data demonstrate that the therapeutic crosslinking procedure is safe when the important theoretical and clinical parameters are observed, and that progression of keratoconus can be prevented. In all, 80% of the published cases show a decrease in corneal curvature of about 2 D, which leads not only to stabilisation but also to an increase in visual acuity.

Setting: Department of Ophthalmology, C.G. Carus University Hospital, Dresden, Germany.

Methods: Four hundred eighty eyes of 272 patients with progressive keratoconus were included in this long-term retrospective study. The maximum follow-up was 6 years. At the first and all followup examinations, refraction, best corrected visual acuity (BCVA), corneal topography, corneal thickness, and intraocular pressure were recorded.

Results: The analysis included 241 eyes with a minimum follow-up of 6 months. The steepening decreased significantly by 2.68 diopters (D) in the first year, 2.21 D in the second year, and 4.84 D in the third year. The BCVA improved significantly (R1 line) in 53% of 142 eyes in the first year, 57% of 66 eyes in the second year, and 58% of 33 eyes in the first year or remained stable (no lines lost) in 20%, 24%, and 29%, respectively. Two patients had continuous progression of keratoconus and had repeat crosslinking procedures.

Conclusions: Despite the low number of patients with a follow-up longer than 3 years, results indicate long-term stabilization and improvement after collagen crosslinking. Thus, collagen crosslinking is an effective therapeutical option for progressive keratoconus. 

The Singapore Eye Foundation Lecture

Professor Mark Mannis, University of California

Presented at the Inaugural Asia Cornea Society Meeting, Singapore on 14-3-08

A summary by International Scientific News Correspondent

 Jenny Deva MD

Professor Mannis started his talk by saying that the management of Keratoconus has always been both Optical and Surgical. Optical devices including controlled physical pressure on the eyes and even contact lenses made of glass from as early as 1880’s was used in the treatment of Keratoconus. The surgical procedures includes corneal flattening devices such as, Intracorneal Corneal Rings, Implantable contact lenses, Penetrating Keratoplasty, Deep ALK, Laser enabled Keratoplasty and of course Collagen Cross Linking (CXL) being the most recent.

In the historical perspective Prof Mannis mentioned how even leeches were used medicinally and applied around the forehead. Then surgeons like Von Grafe applied Silver Nitrate, while others like Elschnig applied heat and cautery to the apex of the cone, then to the periphery all aiming at flattening the cornea. Castroveijo designed a square corneal graft in the late 1950’s. Prof. Sato of Japan attempted correction by doing Internal Keratotomy, but this proved disastrous as the corneas ended in Bullous Keratopathy.

Later Epikeratoplasty was done for Keratoconus. This technique evolved to Deep Anterior Lamellar Keratoplasty (DALK). Intraconeal Corneal Rings have been used with satisfactory results, but in a narrow range of appropriate patients. It however has some Refractive Stability.

Now the latest surgical technology is Collagen Cross Linking (CXL) . This can be done in early Keratoconus, as the ultraviolet light illumination produces covalent bonding of the collagen fibrils, thus increasing the biomechanical strength of the thinning weakened cornea. Personally I believe this may really become suitable as a proactive and preventive treatment for early detected Keratoconus or forme fruste keratoconus in the near future.

Prof Mannis continued his address to say that though surgical procedures help solve the problems at hand, they however do not address why in the first instance a tissue defect in Keratoconus arises. This is of course leads us to question the congenital and hereditary gene factor which can result in the biomechanical weakening of the cornea. He ended on a note that the future of Keratoconus lies perhaps in “Genome Mapping” and “Gene Therapy”.

This presentation was well illustrated and it was an eye opener to the fact that no real “fool-proof” technique or procedure has become, as yet, the treatment of choice for Keratoconus. Further research is still needed to help us find a long lasting solution for that same length of time, from which to go beyond the existing and current mainstream treatment options for Keratoconus. In other words the search for a complete cure is on.

Reported by Jenny Deva MD

Contact Lens Fitting of Keratoconus by Dr Eger

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The Malaysin Experience

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 Enzymatic evidence of the depth dependence of stiffening on riboflavin/UVA treated corneas

Schilde T, Kohlhaas M, Spoerl E, Pillunat LE

Universitäts-Augenklinik Carl Gustav Carus, Fetscherstraße 74, 01307, Dresden, Germany.

Purpose: It has been shown that the treatment of keratoconus with riboflavin/ultraviolet A (UVA) causes significant stiffening of the cornea due to cross-linking. The aim of this study was to evaluate how deep the mechanical stabilization after collagen cross-linking could be shown biochemically.

Method: Ten out of 20 enucleated porcine eyes were treated with riboflavin as a photosensitizer and UVA (370 nm, 3 mW/cm(2), 30 min). The other 10 eyes served as controls. With a Microkeratom device, two flaps with a thickness of 200 microm and a diameter of 8 mm were cut off from each eye and put in a collagenase solution (NaCl plus collagenase A, 1:1). The surfaces of the flaps were measured digitally every day to characterize the dissolving behavior.

Results: The resistance (regarding corneal collagen against enzymatic digestion) of the treated superficial flaps was considerably higher (p=0.001) compared to those that were cut secondarily and to the control flaps. But even the flaps from deeper layers showed a significant increase in resistance (p=0.02) compared with the untreated flaps. The half-life of the surfaces of the treated superficial flaps was 220 h; of those cut secondarily, it was 80 h. Both untreated flaps had a half-life of 50 h.

Conclusions: The biochemical study showed that the treatment of the cornea with riboflavin/UVA leads to significant collagen cross-linking not only in the anterior slice of 200 microm but also in the following 200 microm. This locally limited cross-linking effect may be explained by the absorption behavior for UVA of the riboflavin-treated cornea; 65% of UVA irradiation is absorbed in the first 200 microm and only 25-30% in the next 200 microm. Therefore, deeper-lying structures and especially the endothelium are not affected.

Eberhard Spoerl, Viktoria Zubaty, Frederik Raiskup-Wolf and Lutz E Pillunat

Department of Ophthalmology, University Dresden, Germany.

Aim: The risk of regression after PRK and the tendency to develop keratectasia after LASIK procedure is higher in women. Currently interest is focused on the influence of estrogen on corneal stability after corneal refractive surgery. The aim of this experimental study was to investigate the change in biomechanical properties of the cornea induced by estrogen 

Methods: The influence of estrogen was investigated in 12 fresh porcine corneas incubated in culture medium with 10µM of {beta}-estradiol for 7 days. A group of 12 porcine corneas incubated in culture medium without estradiol for the same time served as a control group. Strips of cornea were cut and the stress-strain was measured in a biomaterial tester. The Young's modulus was calculated. 

Results: During incubation the thickness of the cornea changed in the control group by only 6.4% and in the estradiol group by 12%. However, the difference in the biomechanical stress values at 10% strain was significantly larger. In the control group was the stress value measured 120.18 ± 28.93 kPa and in the estradiol group 76.87 ± 34.63 kPa (p=0.002), representing a reduction of the corneal stiffness by 36% due to the estradiol treatment. 

Conclusion: Estrogen is a modulating factor of the biomechanical properties of the cornea which is not explainable only by an increased swelling. The significance of the hormone status of patients and its influence on the biomechanical stability of the cornea, a determining factor after refractive surgery, have been underestimated and may contribute to the development of keratectasia.

Keratoconus: Age of Onset and Natural History

Dept of Optics University of Granada Spain.

Olivares Jimenez JL, Guerrero Jurado JC, Bermudez Rodriguez FJ, Serrano Laborda D.

Keratoconus is a corneal dystrophy that degrades the optical function of the cornea. The onset of the process manifests optical signs: evolving astigmatism, failure of optical correction by spectacles, and distorted images. We report data from 74 keratoconus patients in need of keratoplasty. The variables studied included sex, age of onset, and refractive error. We find that the average age of the appearance of keratoconus is the second decade of life (mean age of onset = 15.39 years, SD = 3.95), with earlier onset occurring in females that in males, although the differences are not statistically significant. The mean corneal astigmatism before keratoplasty was 4.07 D (SD = 1.57). Optometrists should refer patients for surgery when all optical treatment has failed.

Department of Ophthalmology, Ninewells Hospital and Medical School, Dundee, Scotland, UK

Weed KH, Macewen CJ, Giles T, Low J, McGhee CN.

Aim: To investigate and correlate the corneal, refractive, topographic and familial characteristics of a large cohort with keratoconus.MethodsProspective observational study of 200 consecutive patients presenting with keratoconus during the 4 year-period 1997-2000. Subjects were examined at enrolment and at a final review. Data were collected on demographic characteristics, referral route, symptoms, refractive correction, eye rubbing, family history, medical history, slit-lamp biomicroscopic corneal signs, and computerized corneal topography.

Results: Mean age at enrolment was 30.9+/-10.4 (range, 12.2-72) years (N=200, 62.5% male, 93% white Caucasian) with a 5% family history of keratoconus. Atopic diseases included asthma (23%), eczema (14%), and hay fever (30%). Only 9% wore contact lenses before referral. Mean follow-up was 1004 days +/-282 (range, 390-1335) and 9.7+/-8.9 (range, 1.1-60) years from diagnosis. The mean simulated K1 corneal power at enrolment was 51.74+/-5.36 (range, 42.59-67.32) D and 88.5% exhibited bilateral keratoconus. Fifty-three (15%) topographically confirmed cones exhibited no clinical corneal signs at presentation. At enrollment, 56% had a pachymetry <0.480 mm increasing to 77% at final review. Forty-eight percent of subjects reported significant eye rubbing and there was a highly statistically significant difference (two sample t-test P=0.018) between keratoconus and control groups. TMS-2 axial corneal power was strongly associated with corneal scarring and age at diagnosis. The size of the scarring effect was 2.2 D (95% confidence interval (CI) 1.34, 3.06).

Conclusions: This study provides an overview of a large population with keratoconus highlighting presenting features and clinical and topographic progression over a 4 year-period.

Wednesday, Apr 30, 2008, 8:30 AM -10:15 AM:
   
Reviewing Code: 152 cornea: stroma and keratocytes - CO

Author Block:
    
K.M. Meek1, S. Hayes1, C.S. Kamma-Lorger1, C. Boote1, A.J. Quantock1, D. O'Brart2, J. Marshall2. 1Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom; 2Department of Ophthalmology, St Thomas' Hospital, Kings College London, London, United Kingdom.

Purpose: To measure the changes in collagen interfibrillar spacing and intermolecular spacing in porcine corneas immediately following crosslinking with riboflavin/UVA.

Methods: 42 enucleated porcine eyes were treated using riboflavin/UVA crosslinking following the methods described by Wollensak et al. (Am J Ophthalmol. 2003;135:620-7). After crosslinking, the corneas with a small scleral rim attached, were dissected and examined at the Daresbury synchrotron radiation source. Both small angle and wide angle x-ray scattering studies were performed to measure the central average interfibrillar spacing and the average intermolecular spacing respectively.

Results: There was a reduction in the interfibrillar spacing from 65.9±1.4nm to 60.1±1.8nm after riboflavin/UVA treatment. The intermolecular spacing, however, increased from 1.63± 0.00nm to 1.78 ±0.08nm.

Conclusions: Comparison of the results with those from groups where either riboflavin or UVA treatment was omitted, allowed us to conclude that the reduction in the interfibrillar spacing is due to riboflavin treatment, probably a dehydration effect of the dextran used in the vehicle. The increase in the intermolecular spacing was due to crosslinking, as it only occurred when both riboflavin and UVA were used. Previous studies have revealed that crosslinking collagen fibrils (by natural ageing or by glycation) increases the spacing between the molecules. The present results confirm that the majority of the collagen molecules in the stroma are crosslinked by this treatment.

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Defining Subclinical Keratoconus Using Corneal First-Surface Higher-Order Aberrations

Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany; Department of Ophthalmology, University of Rochester Medical Center, Rochester, New York

Buhren J, Kuhne C, Kohnen T.

PURPOSE: To describe corneal higher-order wavefront aberrations of clinically inconspicuous fellow eyes in patients with early keratoconus (KC).

DESIGN: Prospective comparative case series, conducted at a university eye hospital outpatient clinic.

METHODS: Twenty-three eyes (group 1) were newly diagnosed with KC; 10 eyes (group 2) were asymptomatic fellow eyes that showed neither major topographic anomaly nor clinical signs of KC; 127 healthy eyes of 74 patients served as negative controls (group 3). A seventh-order Zernike decomposition of first-surface aberrations was performed. Single Zernike coefficients, higher-order aberration root mean square (HOA RMS) values, the Z3 index and the output values of discriminant analysis D(13) (with input from groups 1 and 3) and D(23) (groups 2 and 3) were assessed for their usefulness to discriminate between clinically normal fellow eyes, KC eyes and controls by plotting receiver-operating characteristic (ROC) curves.

RESULTS: There were significant differences between group 1 and group 3 for 11 Zernike coefficients, Z3, total HOA RMS, coma RMS and third-order RMS. Group 2 and 3 showed significant differences only for the coefficients Z(3)(-1) and Z(5)(-1). Z(3)(-1), D(13), and D(23) discriminated between groups 1 and 3 with maximum sensitivity and specificity. For discrimination between groups 2 and 3, D(23) turned out to be the best parameter (A(z) ROC = 0.98), followed by Z(3)(-1) (A(z) ROC = 0.96).

CONCLUSIONS: Clinically normal fellow eyes of eyes with early KC showed significant differences of first-surface aberrations compared to normal eyes and could therefore be considered as eyes with subclinical KC.