Patent Application
20070168028
This invention relates generally to the field of intraocular lenses (IOL) and, more particularly, to posterior chamber phakic IOLs.
The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of a crystalline lens onto a retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and the lens.
The optical power of the eye is determined by the optical power of the cornea and the crystalline lens. In the normal, healthy eye, sharp images are formed on the retina (emmetropia). In many eyes, images are either formed in front of the retina because the eye is abnormally long (axial myopia), or formed in back of the retina because the eye is abnormally short (axial hyperopia). The cornea also may be asymmetric or toric, resulting in an uncompensated cylindrical refractive error referred to as corneal astigmatism. In addition, due to age-related reduction in lens accommodation, the eye may become presbyopic resulting in the need for a bifocal or multifocal correction device.
In the past, axial myopia, axial hyperopia and corneal astigmatism generally have been corrected by spectacles or contact lenses, but there are several refractive surgical procedures that have been investigated and used since 1949. Barraquer investigated a procedure called keratomileusis that reshaped the cornea using a microkeratome and a cryolathe. This procedure was never widely accepted by surgeons. Another procedure that has gained widespread acceptance is radial and/or transverse incisional keratotomy (RK or AK, respectively). Recently, the use of photoablative lasers to reshape the surface of the cornea (photorefractive keratectomy or PRK) or for mid-stromal photoablation (Laser-Assisted In Situ Keratomileusis or LASIK) have been approved by regulatory authorities in the U.S. and other countries. All of these refractive surgical procedures cause an irreversible modification to the shape of the cornea in order to effect refractive changes, and if the correct refraction is not achieved by the first procedure, a second procedure or enhancement must be performed. Additionally, the long-term stability of the correction is somewhat variable because of the variability of the biological wound healing response between patients.
Several companies are investigating implantable posterior chamber phakic IOLs, including the Staar ICL lens and the Medennium PRL lens. These and other posterior chamber phakic lenses are described in U.S. Pat. No. 4,769,035 (Kelman), U.S. Pat. No. 6,015,435 (Valunin, et al.) and U.S. Pat. No. 6,106,553 (Feingold), the entire contents of which being incorporated herein by reference. The clinic experience with commercially available posterior chamber phakic lenses has not been entirely satisfactory due to pupillary block, pigment deposition, the need to accurately size the lens, unwanted rotation of the lens and the development of traumatic cataract.
Therefore, a need continues to exist for a safe, stable and biocompatible posterior chamber phakic intraocular lens.
The present invention improves upon the prior art by providing a posterior chamber phakic lens made from an elastomeric, foldable, highly biocompatible and permeable material. The lens has a generally circular optic and a plurality of integrally formed, filament-like haptics. The haptics project posteriorly from the optic and contain a raised feature or ridge that is sandwiched between the posterior iris and the zonules when implanted in an eye. Such a construction has a low vaulting force under compression, is size insensitive, provides for a stable lens once implanted in the eye, helps to avoid pupillary blockage and allows for improved aqueous flow around the natural lens.
Accordingly, one objective of the present invention is to provide a safe and biocompatible intraocular lens.
Another objective of the present invention is to provide a safe and biocompatible intraocular lens that is easily implanted in the posterior chamber.
Still another objective of the present invention is to provide a safe and biocompatible intraocular lens that is stable in the posterior chamber.
Still another objective of the present invention is to provide a safe and biocompatible intraocular lens that does not need highly accurate sizing.
These and other advantages and objectives of the present invention will become apparent from the detailed description and claims that follow.
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This description is given for purposes of illustration and explanation. It will be apparent to those skilled in the relevant art that changes and modifications may be made to the invention described above without departing from its scope or spirit.
