The present invention relates to apparatus for cleaning and sterilizing soft contact lenses and fenestrated hard contact lenses using ultrasonic waves in combination with controlled heating.
The use of hard contact lenses has been commonplace in spite of the difficulties associated with their use. Many persons wish to wear contact lenses for their aesthetic value, while others require contact lenses to correct vision problems which cannot be fully compensated for with normal glasses. These persons must suffer the discomfort associated with wearing the contact lenses, particularly in initially becoming accustomed to their use. Such lenses are often quite expensive, and many individuals, after purchasing the lenses, find that they cannot accustom themselves to their use and must return to regular glasses. Those persons who do wear contact lenses often have continuous eye irritation, particularly if the lenses are worn for too long at one time.
In order to avoid the discomforts associated with the wearing of hard contact lenses, soft contact lenses have been developed which can be worn in relative comfort. Some of the soft contact lenses currently available are constructed of a hydrophilic copolymer and include as much as 50% water absorbed by the copolymer. This structure provides a comfortable soft lens, but they are quite delicate and cannot ordinarily be heated to a sufficient degree or be treated with chemicals to sterilize them. Other soft contact lenses are hydrophobic and are also caustic to extreme heat and harsh chemicals. However, without sterilization, contamination of the eye with micro-organisms growing on or into the lens, such as Pseudomonas, might be able to cause infection or possibly damage of an eye. The Federal Food and Drug Administration recognizes this danger and requires that the wearers of contact lenses be furnished with means enabling them to sterilize the lenses on a daily basis. Since such sterilization procedures are now quite difficult, this limitation has seriously hampered the implementation of soft contact lenses and their availability for use by the general public.
It has therefore been proposed to sterilize soft contact lenses by subjecting them to ultrasonic waves as set forth in my corresponding application for "ULTRASONIC STERILIZATION METHOD AND APPARATUS," Ser. No. 388,848, now abandoned which is herein incorporated by reference. To be acceptable, lens sterilization by ultrasonic waves must be efficient, that is, it must be accomplished within a reasonable period of time by a device that operates overnight, for example, without requiring the attention of the user. The system must further be convenient so that the wearer of the contact lenses follows the recommended sterilization procedure and therefore properly sterilizes the lenses daily.