Method for detecting the presence or absence of an ophthalmic lens, in particular a contact lens, within a receptacle

Abstract

A method for detecting the presence or absence of an ophthalmic lens (10), in particular of a contact lens, within a receptacle (1), including the steps of: detecting infrared radiation coming from at least a portion (3) of the receptacle (1) where the ophthalmic lens (10) is supposedly accommodated, analyzing the detected infrared radiation in a spectral portion in which absorbance (A.sub.L) of a material the ophthalmic lens is made of is significantly different from absorbance (A.sub.R) of a material the receptacle is made of, and from the analysis of the spectral portion detecting the presence or absence of the ophthalmic lens (10) within the receptacle.

Claims

1. A method for detecting the presence or absence of an ophthalmic lens (10) within a receptacle (1), the method comprising the steps of: detecting infrared radiation coming from at least a portion (3) of said receptacle (1) where said ophthalmic lens (10) is supposedly accommodated, analyzing said detected infrared radiation in a spectral portion in which absorbance (AL) of a material said ophthalmic lens (10) is made of is significantly different from absorbance (AR) of a material said receptacle (1) is made of, and from said analysis of said spectral portion detecting the presence or absence of a said ophthalmic lens (10) within said receptacle (1); wherein said step of detecting infrared radiation comprises detecting infrared radiation in a wavelength range of about 6.6 μm to about 10 μm; and wherein said receptacle (1) is illuminated by ambient light only.

2. The method of claim 1, wherein detecting infrared radiation in said wavelength range of about 6.6 μm to about 10 μm is performed using a filter which is permeable in said wavelength range of about 6.6 μm to about 10 μm.

3. The method of claim 2, wherein said step of detecting said infrared radiation is performed using an infrared sensor.

4. The method of claim 3, wherein said step of detecting said infrared radiation is performed using an infrared camera.

5. The method of claim 2, wherein said absorbance (AL) of said material said ophthalmic lens (10) is made of is more than 2% higher than said absorbance (AR) of said material said receptacle (1) is made of, and more than 10% higher than said absorbance (AW, AS) of said liquid.

6. The method of claim 1, wherein said step of detecting said infrared radiation is performed from beneath a bottom (4) of said receptacle (1).

7. The method of claim 1, wherein said step of detecting said infrared radiation is performed from a lateral side of said receptacle (1).

8. The method of claim 1, wherein said step of detecting said infrared radiation is performed with said receptacle being filled with a liquid.

9. The method of claim 1, wherein said receptacle (1) is part of a contact lens package comprising said receptacle (1) and a removable cover which is attached to a top surface (2) of said receptacle (1), and wherein said step of detecting said infrared radiation is performed with said removable cover being attached to said top surface (2) of said receptacle (1).

10. The method of claim 1, wherein said step of detecting said infrared radiation coming from at least a portion of said receptacle (1) is performed by detecting said infrared radiation coming from said whole receptacle (1).

11. The method of claim 1, wherein said step of detecting infrared radiation comprises detecting infrared radiation in a wavelength range of about 6.6 μm to about 8.3 μm.

12. The method of claim 1, wherein said step of detecting infrared radiation comprises detecting infrared radiation in a wavelength range of about 7.7 μm to about 8.3 μm.

13. The method of claim 1, wherein said step of detecting infrared radiation comprises detecting infrared radiation in a wavelength range of about 8.7 μm to about 10 μm.

14. A lens detection station for detecting the presence or absence of an ophthalmic lens (10) in a receptacle (1), the lens detection station comprising a detector adapted and arranged to detect infrared radiation coming from at least a portion (3) of said receptacle (1) where said ophthalmic lens (10) is supposedly accommodated, said detector further being adapted for analyzing said detected infrared radiation in a spectral portion in which absorbance (AL) of a material said ophthalmic lens (10) is made of is significantly different from absorbance (AR) of a material said receptacle is made of, and said detector further being adapted for detecting from said analysis of said spectral portion the presence or absence of a said ophthalmic lens (10) within said receptacle (1); and wherein said detector is adapted for detecting said infrared radiation in ambient light only and in a wavelength range of about 6.6 μm to about 10 μm.

15. The lens detection station of claim 14, wherein said detector is an infrared camera.

16. The lens detection station of claim 14, comprising a filter which is permeable in said wavelength range of about 6.6 μm to about 8.3 μm, or is permeable in said wavelength range of about 8.7 μm to about 10 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the invention will become apparent from the following description of an exemplary embodiment thereof, reference being made to the schematic drawings, in which:

(2) FIG. 1 shows a perspective view of a contact lens package;

(3) FIG. 2 shows an image of a contact lens package containing a contact lens within the receptacle, obtained with an infrared camera arranged beneath the bottom of the receptacle;

(4) FIG. 3 shows an image of a contact lens package containing a contact lens within the receptacle, obtained with an infrared camera arranged at a lateral side of the receptacle;

(5) FIG. 4 shows graphs representing the absorbance of a contact lens made of a silicone hydrogel material and of a receptacle made of polypropylene; and

(6) FIG. 5 shows graphs representing the absorbance of water and of a saline.

DETAILED DESCRIPTION OF EMBODIMENTS

(7) FIG. 1 shows an exemplary embodiment of a receptacle 1 of a contact lens package. Such contact lens package usually comprises the receptacle 1 and a closure, which usually is attached, for example laminated (in case of a foil), to a top surface 2 of the receptacle 1. As the closure is of no specific importance to the invention, it is not shown in the drawings, as detection of the presence or absence of the contact lens can be performed with or without closure. The receptacle 1 is provided with a concavely shaped cavity 3, in which a contact lens is to be accommodated. Corresponding to the concavely shaped cavity 3, the receptacle 1 may have a convexly curved bottom 4. Supporting flanges 5 and 6, which extend at the sides of the receptacle 1 towards the bottom 4 thereof, facilitate a stable placement of the receptacle 1 on a supporting surface. The receptacle 1 may be made of polypropylene, for example. In a packaging station of an automated contact lens manufacturing line, a contact lens is placed into the concavely shaped cavity 3 of the receptacle 1 which is subsequently filled with a liquid, such as water or saline.

(8) In order to be able to detect whether or not a contact lens is present within the cavity 3 of the receptacle 1 a detector which is sensitive to infrared radiation may be arranged in a lens detection station in order to observe the receptacle 1 as a whole or at least a portion thereof which comprises the cavity 3. The detector may be embodied as or comprise an infrared sensor or an infrared camera. In FIG. 1 the directions from which the detector may observe the receptacle 1 are indicated with arrows B and H, respectively. Arrow B indicates that the detector observes the receptacle 1 from beneath the receptacle 1 (i.e. the detector is arranged beneath the bottom 4 of the receptacle). Arrow H indicates that the detector observes the receptacle 1 from a lateral side of the receptacle 1 (in the embodiment shown from about horizontally; i.e. the detector is arranged at a lateral side thereof).

(9) FIG. 2 shows schematically an image obtained with an infrared camera which is arranged beneath the bottom 4 of the receptacle 1, such that the receptacle 1 is observed from underneath. The outlines of the receptacle 1 and its cavity 3 are clearly visible. A contact lens 10 within the cavity 3 of the receptacle 1 is shown in black contrast, corresponding to the absorption of infrared radiation by the material the contact lens is made of, as detected by the infrared camera.

(10) FIG. 3 shows an image from an infrared camera which is arranged at a lateral side of the receptacle (about horizontally relative to the receptacle) such that the receptacle 1 is observed from laterally. Again, the outlines of the receptacle 1 are clearly visible. The contact lens 10 is shown in shades ranging from black to grey. This is a result of the different amounts of absorption of infrared radiation, which is dependent from the length of travel of the infrared radiation through the material of the contact lens 10 within the cavity 3 of the receptacle 1. The observation from a lateral side of the receptacle 1 also may provide clear information as to whether more than one contact lens is present within the receptacle 1.

(11) The diagram in FIG. 4 shows two graphs representing the absorbance A.sub.R of a receptacle made of polypropylene and the absorbance A.sub.L of a contact lens made of a silicone hydrogel material such as from a material obtained from a mixture of the following substances, with “% (w/w)” indicating the weight percentage per total weight:

(12) TABLE-US-00001 Chain-Extended Polydimethylsiloxane (CE-PDMS) 31.83% (w/w) 3-acrylamidopropoyl (trimethyl-siloxy) silane 20.71% (w/w) (TRIS-AAm) 1-propanol (1PrOH) 21.72% (w/w) N,N-Dimethyl acrylamide (DMA) 23.24% (w/w) 2-Hydroxy-2-Methyl-1-Phenyl-1-Propanone (Darocur 1.01% (w/w) 1173) N-(carbonyl-methoxyethylene glycol 2000)-1,2distearoyl- 0.61% (w/w) sn-Glycerol-3-phosphoethanolamine, sodium salt (L-PEG 2000) 1,2-Dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) 0.76% (w/w) 4-Hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl 0.02% (w/w) (H-Tempo) 3-Methacryloxypropyl-tris-(trimethylsiloxy) silane 0.10% (w/w) (TRIS) Copper Phthalocyanine (CuP) Suspension (Source Batch) (Visitint Dispersion)

(13) On the abscissa wavenumbers are shown (unit: cm.sup.−1) while the ordinate shows the absorbance at the respective wavelength (unit: %). No absolute numbers and dimensions are specified on the ordinate, since they depend on the specific detector used, from the amplification factor in the electronics in the respective wavelength range, etc. In any event, the difference in absorptions is sufficient to reliably detect the presence or absence of a contact lens in the cavity 3 of the receptacle 1. The respective wavenumber on the abscissa corresponds to the reciprocal of the wavelength (=1/λ). The two graphs in FIG. 4 show that the receptacle made of polypropylene has peaks of the absorbance in a different wavelength range than the material the contact lens is made of. Thus, in the analysis of the detected infrared radiation the two materials can be reliably distinguished. For example, in the embodiment shown a first wavenumber range of 1300 cm.sup.−1 to 1210 cm.sup.−1 (corresponding to a wavelength range of 7.7 μm to 8.3 μm) and a second wavenumber range of 1150 cm.sup.−1 to 1000 cm.sup.−1 (corresponding to a wavelength range of 8.7 μm to 10 μm) are particularly advantageous, since in these ranges the absorbance A.sub.L of the contact lens and the absorbance A.sub.R of the polypropylene receptacle are significantly different so that a reliable detection of the contact lens can be performed.

(14) The graphs shown in the diagram of FIG. 5 shows the absorbance A.sub.W of water and the absorbance A.sub.S of a saline, respectively. Again, on the abscissa wavenumbers are shown while the ordinate shows the absorption at the respective wavelength in %. The two graphs representing the respective absorbance A.sub.W and A.sub.S are very similar to each other and have peaks in the absorbance practically in the same wavelength range.

(15) A comparison of the absorbance A.sub.R, A.sub.L, A.sub.W and A.sub.S represented by the graphs shown in FIG. 4 and FIG. 5 shows that the absorbance A.sub.L of the contact lens has maxima in a wavenumber range (wavelength range) which is clearly distinct from the maxima in absorbance A.sub.R, A.sub.W and A.sub.S of the polypropylene receptacle and of water and saline, respectively. Thus, the passive detection method employing a detector for detecting infrared radiation and for the analysis of the detected infrared radiation may lead to clear and unambiguous results as to whether or not a contact lens is accommodated within the receptacle, and as to whether or not more than one contact lens is present within the receptacle. The detection method may be performed even with contact lens packages in which the receptacle has been loaded with a contact lens and has been filled with water or saline, and after the receptacle has been provided with a removable closure (for example a foil), which may have been attached, for example laminated, to a top surface of the receptacle. However, detection may also be performed when the receptacle has been loaded with a contact lens but before water or saline have been added, or after water or saline have been added but before the foil has been attached to the receptacle.

(16) Although the invention has been described with the aid of a specific embodiment, it is evident to the person skilled in the art that this embodiment has been described by way of example only while it represents a more general teaching, and that various changes and modifications are conceivable without departing from this general teaching underlying the invention. Therefore, the scope of protection is not intended to be limited by the embodiment described, but rather is defined by the appended claims.