METHOD OF DETECTING THE ORIENTATION OF AN OPHTHALMIC LENS IN ITS PACKAGE

This invention related to methods of inspecting ophthalmic lenses during their production.

RELATED APPLICATION

This application is a non-provisional filing of a provisional application, U.S. Serial No. 60/947,059, filed on June 29, 2007.

BACKGROUND

Contact lenses have been used commercially to improve vision since the 1950s. The first contact lenses were made of hard materials. Although these lenses are currently used, they are not suitable for all patients due to their poor initial comfort. Later developments in the field gave rise to soft contact lenses, based upon hydrogels, which are extremely popular today. Further developments have lead to the development of silicone hydrogel lenses. Such silicone hydrogel lenses are known higher oxygen permeabilities and such are often more comfortable to wear than contact lenses made of hard materials. However, silicone hydrogel lenses are not without problems.

Silicone hydrogel lenses may be creased or otherwise physically distorted during their production. This problem can be seen when the lenses are sterilized. Typically, silicone hydrogel lenses are packaged in individual container containing ophthalmic packaging solutions and heated to temperatures of about 100 ⁰ C or greater. Due to their flexible nature, hydrogel lenses may be inverted during their preparation. Inversion means that the lenses are inside out with respect to the normal concave and convex surfaces of the lens. If a user were to place an inverted lens on his or her eye, the normal front curve (convex portion) would contact the user's eye instead of the normal back curve (concave portion). Classes of hydrogels, such as silicone hydrogels are subject to distortions (such as diameter) if such lenses are sterilized in an inverted position. Therefore, a method of determining if lenses are inverted prior to sterilization in order to identify lenses that are likely to be distorted would be useful. This need is met by the following invention.

BRIEF DESCRIPTION OF THE DRAWING Fig 1 Illustrates a lens inspection system of the invention. Fig. 2 Illustrates the image of an non-inverted and an inverted lens.

DETAILED DESCRIPTION OF THE INVENTION This invention includes a method of determining whether an ophthalmic lens that is suspended in a solution is inverted in its packaging comprising illuminating the ophthalmic lens and its solution in its packaging, acquiring a image of the illuminated ophthalmic lens and analyzing the image to determine whether the ophthalmic lens is inverted.

As used herein "ophthalmic lenses " refers to ophthalmic devices that reside in or on the eye. Ophthalmic lenses can provide optical correction or may be cosmetic. The term lens includes but is not limited to soft contact lenses, intraocular lenses, overlay lenses, ocular inserts, and optical inserts. The preferred lenses of the invention are silicone hydrogel lenses described in in US Patent No. 5,710,302, WO 9421698, EP 406161 , JP 2000016905, U.S. Pat. No. 5,998,498, US Pat. App. No. 09/532,943, U.S. Patent No. 6,087,415, U.S. Pat. No. 5,760,100, U.S. Pat. No.5,776, 999, U.S. Pat. No. 5,789,461 , U.S. Pat. No. 5,849,811 , and U.S. Pat. No. 5,965,631. The foregoing references are hereby incorporated by reference in their entirety. The preferred lenses include but are not limited to silicone hydrogels such as galyfilcon A, senofilcon A, genfilcon A, lenefilcon A, comfilcon A, acquafilcon A, balafilcon A, lotrafilcon A, narafilcon A, and silicone hydrogels as prepared in U.S. Pat. No. 5,998,498, US Pat. App. No. 09/532,943, a continuation-in-part of US Pat App. No. 09/532,943, filed on August 30, 2000, U.S. Patent No. 6,087,415, U.S. Pat. No. 5,760,100, U.S. Pat. No.5,776, 999, U.S. Pat. No. 5,789,461 , U.S. Pat. No. 5,849,811 , and U.S. Pat. No. 5,965,631. The most preferred ophthalmic lenses are senofilcon A, and acquafilcon A. These patents as well as all other patents disclosed in this application are hereby incorporated by reference in their entirety.

The "solution(s)" of the invention may be any water-based solution that is used for the sterilization and storage of contact lenses. Typical solutions include, without limitation, saline solutions, other buffered solutions, and

deionized water. The preferred solution is saline solution containing salts including, without limitation, sodium chloride, sodium borate, sodium phosphate, sodium hydrogenphosphate, sodium dihydrogenphosphate, or the corresponding potassium salts of the same. These ingredients are generally combined to form buffered solutions that include an acid and its conjugate base, so that addition of acids and bases cause only a relatively small change in pH. The buffered solutions may additionally include 2-(N- morpholino)ethanesulfonic acid (MES), sodium hydroxide, 2,2- bis(hydroxymethyl)-2,2',2"-nithlotriethanol, n-tris(hydroxymethyl)methyl-2- aminoethanesulfonic acid, citric acid, sodium citrate, sodium carbonate, sodium bicarbonate, acetic acid, sodium acetate, ethylenediamine tetraacetic acid and the like and combinations thereof. Preferably, the solution is a borate buffered or phosphate buffered saline solution.

"Packaging" refers to any receptacle that may be used to sterilize silicone hydrogel ophthalmic lens. Examples of such receptacles are disclosed in the following publications, which are hereby incorporated by reference in their entirety, WO 2005/082721 , WO 03/016175, US 2004/0238380, U.S. Patent Nos. D 458,023; 4,691 ,820; 5,054,610; 5,337,888; 5,375,698; 5,409,104; 5,467,868; 5,515,964; 5,609,246; 5,695,049; 5,697,495; 5,704,468; 5,711 ,416; 5,722,536; 5,573,108; 5,823,327; 5,704,468; 5,983,608; 6,029,808; 6,044,966; 6,401 ,915, 7,086,526. The foregoing packaging is delivered to the consumer sealed by a cover. Examples of covers include but are not limited to foil laminates, transparent laminates, hardened plastics and flexible plastics . The methods of the invention may be used to inspect sealed packages, however, it is preferred that the packaging is inspected prior to sealing it with a cover.

"Inverted" refers to the orientation of the ophthalmic lens. If a user were to place an inverted lens on his or her eye, the normal front curve (convex portion) would contact the user's eye instead of the normal back curve (concave portion). "Illuminating" refers to shining a light on the lens. It is preferred that the lens is illuminated by a strobe light that flashes to illuminate the lens. The preferred wavelength of said flash is about 375 nm + 10 to about 700 nm. The preferred duration of said flash is about 100 microseconds to

about 1000 microseconds with an intensity of about 900 and to about 1200 mA. It is preferred that light source illuminates the ophthalmic lens from the convex side to the concave side whether or not the lens in an invented position.

The term "acquiring" refers to capturing the image of lens with a camera. The preferred camera is a Smart Camera or Smart Image Sensor. The preferred cameras are sold by DVT Inc. and Cognex Inc. The particularly preferred cameras are Smart Image Sensor 544 from DVT, Basler 201 B, and Dalsa Pentara SA. The term "analyzing" refers the use of algorithms with a computer where, the algorithms evaluate the acquired image with respect to images of non-inverted lenses. Suitable algorithms include but are not limited to BLOB analyses and Sobel edge detection algorithms. In addition, the inverted lens may be detected by comparing the diameter of an inverted lens, to the diameter of a non-inverted lens.

Further the invention includes an apparatus for determining whether an ophthalmic lens is inverted in its packaging comprising a light source, a camera and a computer. The terms ophthalmic lenses, solutions, packaging, analyzing, inverted, and acquiring have their aforementioned meanings and preferred ranges. Still further the invention includes ophthalmic lenses that are inspected by a method comprising illuminating the ophthalmic lens and its solution in its packaging, acquiring a image of the illuminated ophthalmic lens and analyzing the image to determine whether the ophthalmic lens is inverted. The terms ophthalmic lenses, solutions, packaging, analyzing, inverted, and acquiring have their aforementioned meanings and preferred ranges.

Referring to Figure 1 , a series of ophthalmic lenses 10 are contained in the bowl of uncovered contact lens packages Yl. Although not illustrated the lenses are contained suspended in saline packaging solution. The packages are moved along a conveyor belt the direction of arrow 14. Backlight 16 sits below packages 12_below the convex side of lenses 10. Camera 18 sits above packages 12 and points to the concave side of lenses 10. As the packages moves along the conveyor, a proximity sensor, not shown, triggers the flash of backlight 16 and the capture of the image by camera 18. The hashed line 20 represents the center point of the optics. The captured image is analyzed to determine if the lens is inverted. Figure 2 illustrates an image of a non-inverted

lens and inverted lens. In an industrial application it is preferred that the inverted lens be discarded prior to covering and sterilizing the lens.