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UV-X^TM - Illumination system for corneal cross linking

UV-X Illumination system for corneal cross linking

UV-X^TM is an outstanding, CE-approved illumination device for corneal cross linking that was developed by an experienced team in collaboration with the inventors of the procedure, Prof. Theo Seiler and Prof. Eberhard Spoerl. It was designed with a special focus on both safety and effectivity of the procedure, embodying the cutting-edge knowledge in the field of corneal cross-linking.

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Specifications

Advantages of the UV-X^TM device

• Homogeneity of illumination

All safety considerations regarding the cross-linking procedure assume an optically homogeneous irradiation of the cornea. Optical inhomogeneities such as hot spots that occur during direct LED illumination can lead to damages in the corneal endothelium which represents the most endangered structure. Thus, a homogeneous illumination of the cornea as it is provided by the patented beam homogenizing optics¹ of the IROC UV-X^TM device is essential for a safe treatment procedure.

A patented beam homogenizing micro structure¹ along with a special optical design according to Koehler provide excellent homogeneity in the UV-X^TM device.

Scanning electron microscopy image of the patented beam homogenizing micro structure used in the UV-X device.

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¹ See patent description: Semchishen V.A., Mrochen M., Seminogov V.N., Panchenko V.Y., Seiler T. − Light beam shaping and homogenization (LSBH) by irregular microlens structure for medical applications. SPIE Proc. 1998, 3251, 28-33

Some authors have used direct illumination of the cornea by means of ultraviolet LEDs. Yet, direct illumination with LEDs causes highly inhomogeneous intensity distributions that might cause endothelial cell damage. Direct LED illumination should not be used!

Homogeneous irradiation with UV-X (left) vs. highly inhomogeneous irradiation with direct LED illumination (right).

• Tolerance towards treatment distance

The overlap of light spots created by direct LED illumination strongly depends on the distance between the LEDs and the cornea. Deviations of as little as 2.0 mm from the ideal treatment distance can either cause endothelial damage or render the treatment ineffective. The special homogenizing optics of the IROC UV-X^TM makes the device much more insensitive towards variations in treatment distance. Additionally, variations in treatment distance of the UV-X^TM device do not bear the risk of causing intensities above the damage threshold as the maximum intensity is only achieved in the ideal treatment distance.

Measured sensitivities to variations in treatment distance. In contrast to the UV-X device (blue line) direct LED illumination is highly sensitive to small variations (grey line).

• Minimization of radiation at the retina

The safety design of the IROC UV-X^TM device uses a special beam path according to Koehler. Due to this optical design the necessary radiant exposure at the cornea is immediately dissipated behind the cornea as a result of the optically diverging beam within the eye. Experimental measurements in porcine eyes have showen radiant exposures at the retina that were far below the laser safety thresholds, thus ensuring very safe treatments.

Safety design of the UV-X device: An optical design according to Koehler reduces the radiant exposure at the retina to a minimum (left). The safety was further checked experimentally (right).

• Precompensation of corneal curvature

The curvature of the corneal surface causes additional inhomogeneities when using direct LED illumination. The converging illumination beam of the UV-X^TM device is already precompensating the corneal curvature thus minimizing reflection losses and zone enlargements.

Precompensation of the corneal curvature by a converging beam like in the UV-X (left) helps to avoid additional inhomogeneities that occur in direct LED illumination (right)

• Intensity check prior to each treatment

As an additional safety feature the output intensity of the UV-X^TM device can be checked prior to each treatment using the UV light meter that is delivered with the system. IROC is providing information on the tolerable intensity range.

The output intensity of the UV-X device can be checked prior to each treatment.