CA1170080A - Method for measurement of the cavity volume of soft contact lenses and the apparatus for this measuring method - Google Patents
Method for measurement of the cavity volume of soft contact lenses and the apparatus for this measuring methodInfo
- Publication number
- CA1170080A CA1170080A CA000400193A CA400193A CA1170080A CA 1170080 A CA1170080 A CA 1170080A CA 000400193 A CA000400193 A CA 000400193A CA 400193 A CA400193 A CA 400193A CA 1170080 A CA1170080 A CA 1170080A
- Authority
- CA
- Canada
- Prior art keywords
- liquid
- capillary tube
- volume
- measurement
- measuring capillary
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F17/00—Methods or apparatus for determining the capacity of containers or cavities, or the volume of solid bodies
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
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- Health & Medical Sciences (AREA)
- Vascular Medicine (AREA)
- Heart & Thoracic Surgery (AREA)
- Fluid Mechanics (AREA)
- Ophthalmology & Optometry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biomedical Technology (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Eyeglasses (AREA)
- Sampling And Sample Adjustment (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A method for measurement of cavity volume of soft contact lenses which consists in free resting of the contact lens immersed in liquid on a planar or convex (preferably spherical) surface, suction off the liquid enclosed between the inner surface of lens and the planar or convex surface, and measuring the volume of sucked-off liquid. This volume is indicated in a measuring capillary tube by the shift of mercury droplet separating the immersion liquid on both sides. And an apparatus for measurement by the invented method, which consists of a vessel with immersion liquid, having a plane or convex surface of its bottom provided with a hole, which is connected with a measuring capillary tube through a broadened inlet chamber containing a mercury drop. The measuring capillary tube is furnished with a scale corres-ponding to its volume and is connected, at the outlet, with a drain or pressure reservoir through a broadened outlet chamber and a unit for pressure variation.
A method for measurement of cavity volume of soft contact lenses which consists in free resting of the contact lens immersed in liquid on a planar or convex (preferably spherical) surface, suction off the liquid enclosed between the inner surface of lens and the planar or convex surface, and measuring the volume of sucked-off liquid. This volume is indicated in a measuring capillary tube by the shift of mercury droplet separating the immersion liquid on both sides. And an apparatus for measurement by the invented method, which consists of a vessel with immersion liquid, having a plane or convex surface of its bottom provided with a hole, which is connected with a measuring capillary tube through a broadened inlet chamber containing a mercury drop. The measuring capillary tube is furnished with a scale corres-ponding to its volume and is connected, at the outlet, with a drain or pressure reservoir through a broadened outlet chamber and a unit for pressure variation.
Description
~7(~
The invention pertains to a method for measure-ment of the cavity volume of soft contact lenses and to the apparatus for performance of this method.
Until the present time, the following methods have been used for characterization of the shape of soft contact lenses (either hydrophilic or hydrophobic), which is necessary for their correct selection according to the e~amined shape of patient's eye:
1. A needle is shifted into the center of lens, which freely rests by its circumference on a planar base, as far as to the contact with the inner apex of lens. The sagittal depth of lens determined in this way serves, together with the measured diameter of lens, as a rough measure of its total convexity.
The invention pertains to a method for measure-ment of the cavity volume of soft contact lenses and to the apparatus for performance of this method.
Until the present time, the following methods have been used for characterization of the shape of soft contact lenses (either hydrophilic or hydrophobic), which is necessary for their correct selection according to the e~amined shape of patient's eye:
1. A needle is shifted into the center of lens, which freely rests by its circumference on a planar base, as far as to the contact with the inner apex of lens. The sagittal depth of lens determined in this way serves, together with the measured diameter of lens, as a rough measure of its total convexity.
2. Similarly, a needle is slided into the lens resting symmetrically on a circular edge of chosen diameter and the mean curvature of lens above this diameter is measured in this way.
3. A lens freely placed in an immersion liquid in a cell is measured by means of a projection or photo-graphic equipment.
4. A lens freed of surface water is measured by reflection methods to determine the whole course of its inner or outer curves.
The methods 1, 2 and 4 are subjected to errors, arising from the deformation of soft lens by gravitation forces r Such measurement is entirely impossible with ultrathin lenses.
The method 3, where the immersed lens is not subjected to these deforming forces, is reliable ~or measurement of the lens shape, but it is very elaborate, because pictures should be made and additionally precisely measured to evaluate the projection. In addition to this, strong reflections of tangentially illuminated surfaces ~'7~
occur at the side projection, thus making impossible the realiable measuremen~ of inner surface, which shape is even more impoxtant for appli.cation than the shape of outer surface of lens.
Above shortcomings are removed by the method-and apparatus of the present invention for measurement of the cavity volume of soft contact lenses according to the inven-tion.
Therefore r according to the present invention there is provided a method for measurement of cavity volume of soft contact lenses, wherein a contact lens in a liquid immersion, is allowed freely rest on a planar or convex suction surface and the immersion liquid is then pumped off from the space enclosed between the inner surface of contact lens and the planar or convex surface and its volume is measured.
Preferably, the liquid immersion is water or physiologic saline.
The volume of sucked-off liquid may be advanta-geously indicated by the shift of mercury column enclosed from both .sides by the measured liquid in a capillary tube.
For this purpose, the initial position of mercury drop may be easily adjusted by broadening of the capillary tube upwards at least at one of its ends. The extreme position of mercury drop, at one or at both ends of capillary tube, is secured by broadening the inner diameter of capillary tube at the end up-wards into a chamber of multiple size of inner diameter, so that mercury cannot be washed off even not a strong flow of liquid. If the flow of liquid ceases, mercury rests in the form of a ball in the broadened inlet of chamber and closes the capillar~ tube in the defined way. At the inverse flow of liquid, the mercury drop moves as a short column along the measuring capillary tube. At the same time, mercury is strongly p~shed to khe wall of capillary by its high surface tension, so that only a very ;~7~
thin film of liquid remains on the wall in the position of mercury drop and the space of capillary is very precisely divided by the mercury drop. The pressure pushing the mercury drop to walls is inversely proportional to the diameter of capillary according to p = 0-0153 (kg/cm2) d where p is the pressure and d is the inner diameter of capillary in mm.
If one assumes, in the first approximation, that the thickness of the thin liquid film, adhering to the wall of capillary in the place of passing mercury drop, is inversely proportional to the pressure developed by drop on the wall, i-t can be concluded that the ratio of the volume of liquld shifted in the capillary to the volume of adhering film is constant for the given speed of shifting and does not depend on the inner diameter of capillary.
This explains the fact, -that the accuracy of measured volume is preserved in this method, even when extraordina-rily fine capillaries are used, which enable to measure precisely also very small amounts of liquid~
It was found, that only very small underpressure is needed to suck perfectly a soft lens to the suitably chosen surface (base), viz. 2 to 10 cm of water column.
~his holds also for lenses of maximal thickness, e.g. for lenses for aphakick.s. This fact gives evidence about advantages of this arrangement. Measurements of the sucked-o~f volurrre by means of a piston or a corrugated box would be subjected to large errors because much higher force would be necessary to overpower mechanical resistances than is the~minimal ~force needed to suction. In addition to this, mechanical parts would require high precision, because the accuracy of measurement in limits of one mm3 of sucked-off -- 3 ~
~ . !
3~
liquid is needed.
Numerous methods and the corresponding equipments were developed for the precise measurement of very small amounts of liquid, e.g~ for volumetric microanalysis, where the zero position in measuri.ng tube is automatically set.
If mechanically controlled piston devices are not concerned, which always demand high preclsion and therefore are rela-tively coskly, numerous so called automatic microburettes were developed, where the level of liquid is set in the measuring tube by a hydrostatically operated equipment mostly by allowing the liquid exceeding the zero level to flow off through an overflow or by suction this liquid off through a fixed au~iliary thin capillary, which is dipped into a pre-cise depth~ A disadvantage of these~devices consists in the nonuniform shape of meniscus of small-diameter tubes, which causes differences in the zero setting as a consequence of various wetting of wall by the liquid.
According to the present invention there is also provided an apparatus for measurement of cavity volume of soft contact lenses which consists of a vessel for immersion liquid with a bottom provided with a planar or convex suction surface having a hole, which is connected with a measuring capillary tube also fil]ed with the immersion liquid. The measuring capillary tube is provided with a scale, correspond-ing to the volume of measuring capillary tube, which tube isconnected at the inlet with a broadened inlet chamber placed above the measuring capillary tube. The outlet of measuring capillary tube is connected by means of a broadened outlet chamber with a drain of measured liquid, while a drop of mercury is placed in the broadened inlet chamber.
Preferably, the bottom may be provided with a spherical suction surface.
The outlet chamber is advantageowsly connected to the unit for pressure variation. This unit for pressure , . ~, ~:~7~0~
variation may consists advantageously of a two-way cock or a system of valves with analogous function, which serves for connecting the outlet charnber either with an over-pressure reservoir or with an underpressure drain.
Applica-tion oE the spherical suction surface of radius 12.5 mm is of particular advantage. This surface has on diameters 13.5 and 1~.5 mm about the same tangen-t as an average eye on the same diameter~ The difference between the volume of section caps of an average eye and the volume of the spherical cap of the same width and radius 12.5 mm is therefore practically constant (67 mm3).
If we set the linear volume scale at the capillary tube in such a way, that the initial position of mercury drop points to -67 mm3 on the scale, the position of drop after suction of lens indicates directly the difference between the cavity volume of lens and the volume of axial segment o-f an average eye of the same width, i.e. so called suction volume, which serves for suction of lens to an average eye.
If the patient's eye was measured in such a way, that the d.eviation of the volume of :L3.5 to 1~.5 mm wide axial se~nent of its eye from the segment of an average eye of the same width may be derived from the obtained para-meters, this deviation may be direct:Ly compared with the measured volume devia-tion of lens from the same average eye. It can be objectively ascertained in this way, which suction volume will operate in the application of the measured lens to the measured eye.
The volume of sucked-off liquid is relatively small, of order of magnitude in tens of microliters. If the measurement accuracy about plus-minus one microliter is required and if the position of mercury droplet should be rea~ on the scale by naked eye with the same accuracy, without using a magnifying glass or cathetometer, the inner diameter of capillary tube should not be larger than '' ' ' ' ~ ' ~
.
.
7(30~3~
about 1 mm. On the other hand, extremely small diameters cannot be used for the reduced visibility of column and for increasing errors due to irregular or irreproducible wetting of capillary wall. As follows from experience, the most suitable are capillary tubes of inner diameter 0.5 to 2 mm.
Concerning the material of capillary tube, its transparency or at least a suitable translucency is a condi-tion.
Glass capillary tubes are obviously the best.
On the other hand, it is simpler to use for measurement capillary tubes which serve, at the same time, for connec-tion with the vessel and also with the controlling pneu-matic eqlaipment. Since the pressure changes inside the systern are minimal, even capillary tubes made of relatively soft material may be used, e.g. of plasticized poly(vinyl chloride) or silicon rubber.
The position of measuring capillary tube has no effect on the accuracy of measurement. It may be placed vertically, horizontally, or in any s:Loped position.
The progressiveness of invention, in comparison with the recent state of technique, consists mainly in the possibility to measure fast and reliably also ultrathin contact lenses, while the measurement is faster than with known methods, the investment cost is substantially lower, and the measurement does not require professionally skilled attendance.
. An embodiment of the invention will now be described as an example, without limitative manner, having .reference to the drawing, wherein the simple figure dia-,' gramrnatically shows the apparatus fo~ measurement of cavityvolume of soft contact lenses.
The apparatus consists of the vessel 1 for immersion liquid 2, which has on ts bo-ttom 3 a planar or convex, e.g. spherical, suction surface furnished with the hole 4, which is connected with the measuring capillary tube 5 also filled with the same immersion liquid. The measuring capillary tube S is provided with the scale 6, corresponding to the volume of measuring capillary tube 5, which inlet communicates with the broadened inlet chamber 7 placed above the measuring capillary tube 5. The outlet of measuring capillary tube 5 is connected through the broadened outlet chamber 8 with the drain oE measured liquid. A drop of mercury 9 is placed in -the 'broadened inlet chamber 7. The outlet chamber 8 is connected to the unit for pressure variation, which consists of the two-way cock 10, or a set of valves of the analogous function, and serves for connec-ting the outlet chamber 8 either with the overpressure reservoir 11 or with the underpressure drain 1~. .
~ The apparatus is ready for measurement if all its capillary tubings, the measuring capillary tube and the vessel with lens are filled wi-th physiologic saline and the mercury drop 9 is transferred into the broadened inlet chamber 3 by'the flow of solution from the reservoir llo Then, measurement is carried out by closing the cock 10 for shorter time (about half a minute) to allow the mercury drop 9 sit into the upper inlet of measuring capillary tube 5 and the contact lens 14 placed in the vessel 1 perfectly rests on the suction surface of bot-tom 3 of the vessel 1. Then, the capillary is connected with the below - placed drain 12 by turning the two-way cock 10, thus causing the perfect suction of contact lens 14 to the, ' bottom 3 of vessel I by the created underpressure, and the sucked-off volume is indicated by the position of mercury drop 9 in the measuring capillary -tube 5. The sought 'cavity ~olume is then the sum of the indicated volume and the volume assumed by the section cap of bottom 3 of ~7(~[~
vessel 1 covered with the con-tact lens of known diame-ter.
If the bottom is spherical, the cavity volume may be read directly by setting the sliding scale 6, which sits close to the measuring capillary tube 5, by means of the auxilia-ry scale 13 of lens diameter, into such position, that the upper inle-t of measuring eapillary tube is at the volume on the scale 6 corresponding to the volume assumed by spherical cap of -the diameter of measured contaet lens.
The methods 1, 2 and 4 are subjected to errors, arising from the deformation of soft lens by gravitation forces r Such measurement is entirely impossible with ultrathin lenses.
The method 3, where the immersed lens is not subjected to these deforming forces, is reliable ~or measurement of the lens shape, but it is very elaborate, because pictures should be made and additionally precisely measured to evaluate the projection. In addition to this, strong reflections of tangentially illuminated surfaces ~'7~
occur at the side projection, thus making impossible the realiable measuremen~ of inner surface, which shape is even more impoxtant for appli.cation than the shape of outer surface of lens.
Above shortcomings are removed by the method-and apparatus of the present invention for measurement of the cavity volume of soft contact lenses according to the inven-tion.
Therefore r according to the present invention there is provided a method for measurement of cavity volume of soft contact lenses, wherein a contact lens in a liquid immersion, is allowed freely rest on a planar or convex suction surface and the immersion liquid is then pumped off from the space enclosed between the inner surface of contact lens and the planar or convex surface and its volume is measured.
Preferably, the liquid immersion is water or physiologic saline.
The volume of sucked-off liquid may be advanta-geously indicated by the shift of mercury column enclosed from both .sides by the measured liquid in a capillary tube.
For this purpose, the initial position of mercury drop may be easily adjusted by broadening of the capillary tube upwards at least at one of its ends. The extreme position of mercury drop, at one or at both ends of capillary tube, is secured by broadening the inner diameter of capillary tube at the end up-wards into a chamber of multiple size of inner diameter, so that mercury cannot be washed off even not a strong flow of liquid. If the flow of liquid ceases, mercury rests in the form of a ball in the broadened inlet of chamber and closes the capillar~ tube in the defined way. At the inverse flow of liquid, the mercury drop moves as a short column along the measuring capillary tube. At the same time, mercury is strongly p~shed to khe wall of capillary by its high surface tension, so that only a very ;~7~
thin film of liquid remains on the wall in the position of mercury drop and the space of capillary is very precisely divided by the mercury drop. The pressure pushing the mercury drop to walls is inversely proportional to the diameter of capillary according to p = 0-0153 (kg/cm2) d where p is the pressure and d is the inner diameter of capillary in mm.
If one assumes, in the first approximation, that the thickness of the thin liquid film, adhering to the wall of capillary in the place of passing mercury drop, is inversely proportional to the pressure developed by drop on the wall, i-t can be concluded that the ratio of the volume of liquld shifted in the capillary to the volume of adhering film is constant for the given speed of shifting and does not depend on the inner diameter of capillary.
This explains the fact, -that the accuracy of measured volume is preserved in this method, even when extraordina-rily fine capillaries are used, which enable to measure precisely also very small amounts of liquid~
It was found, that only very small underpressure is needed to suck perfectly a soft lens to the suitably chosen surface (base), viz. 2 to 10 cm of water column.
~his holds also for lenses of maximal thickness, e.g. for lenses for aphakick.s. This fact gives evidence about advantages of this arrangement. Measurements of the sucked-o~f volurrre by means of a piston or a corrugated box would be subjected to large errors because much higher force would be necessary to overpower mechanical resistances than is the~minimal ~force needed to suction. In addition to this, mechanical parts would require high precision, because the accuracy of measurement in limits of one mm3 of sucked-off -- 3 ~
~ . !
3~
liquid is needed.
Numerous methods and the corresponding equipments were developed for the precise measurement of very small amounts of liquid, e.g~ for volumetric microanalysis, where the zero position in measuri.ng tube is automatically set.
If mechanically controlled piston devices are not concerned, which always demand high preclsion and therefore are rela-tively coskly, numerous so called automatic microburettes were developed, where the level of liquid is set in the measuring tube by a hydrostatically operated equipment mostly by allowing the liquid exceeding the zero level to flow off through an overflow or by suction this liquid off through a fixed au~iliary thin capillary, which is dipped into a pre-cise depth~ A disadvantage of these~devices consists in the nonuniform shape of meniscus of small-diameter tubes, which causes differences in the zero setting as a consequence of various wetting of wall by the liquid.
According to the present invention there is also provided an apparatus for measurement of cavity volume of soft contact lenses which consists of a vessel for immersion liquid with a bottom provided with a planar or convex suction surface having a hole, which is connected with a measuring capillary tube also fil]ed with the immersion liquid. The measuring capillary tube is provided with a scale, correspond-ing to the volume of measuring capillary tube, which tube isconnected at the inlet with a broadened inlet chamber placed above the measuring capillary tube. The outlet of measuring capillary tube is connected by means of a broadened outlet chamber with a drain of measured liquid, while a drop of mercury is placed in the broadened inlet chamber.
Preferably, the bottom may be provided with a spherical suction surface.
The outlet chamber is advantageowsly connected to the unit for pressure variation. This unit for pressure , . ~, ~:~7~0~
variation may consists advantageously of a two-way cock or a system of valves with analogous function, which serves for connecting the outlet charnber either with an over-pressure reservoir or with an underpressure drain.
Applica-tion oE the spherical suction surface of radius 12.5 mm is of particular advantage. This surface has on diameters 13.5 and 1~.5 mm about the same tangen-t as an average eye on the same diameter~ The difference between the volume of section caps of an average eye and the volume of the spherical cap of the same width and radius 12.5 mm is therefore practically constant (67 mm3).
If we set the linear volume scale at the capillary tube in such a way, that the initial position of mercury drop points to -67 mm3 on the scale, the position of drop after suction of lens indicates directly the difference between the cavity volume of lens and the volume of axial segment o-f an average eye of the same width, i.e. so called suction volume, which serves for suction of lens to an average eye.
If the patient's eye was measured in such a way, that the d.eviation of the volume of :L3.5 to 1~.5 mm wide axial se~nent of its eye from the segment of an average eye of the same width may be derived from the obtained para-meters, this deviation may be direct:Ly compared with the measured volume devia-tion of lens from the same average eye. It can be objectively ascertained in this way, which suction volume will operate in the application of the measured lens to the measured eye.
The volume of sucked-off liquid is relatively small, of order of magnitude in tens of microliters. If the measurement accuracy about plus-minus one microliter is required and if the position of mercury droplet should be rea~ on the scale by naked eye with the same accuracy, without using a magnifying glass or cathetometer, the inner diameter of capillary tube should not be larger than '' ' ' ' ~ ' ~
.
.
7(30~3~
about 1 mm. On the other hand, extremely small diameters cannot be used for the reduced visibility of column and for increasing errors due to irregular or irreproducible wetting of capillary wall. As follows from experience, the most suitable are capillary tubes of inner diameter 0.5 to 2 mm.
Concerning the material of capillary tube, its transparency or at least a suitable translucency is a condi-tion.
Glass capillary tubes are obviously the best.
On the other hand, it is simpler to use for measurement capillary tubes which serve, at the same time, for connec-tion with the vessel and also with the controlling pneu-matic eqlaipment. Since the pressure changes inside the systern are minimal, even capillary tubes made of relatively soft material may be used, e.g. of plasticized poly(vinyl chloride) or silicon rubber.
The position of measuring capillary tube has no effect on the accuracy of measurement. It may be placed vertically, horizontally, or in any s:Loped position.
The progressiveness of invention, in comparison with the recent state of technique, consists mainly in the possibility to measure fast and reliably also ultrathin contact lenses, while the measurement is faster than with known methods, the investment cost is substantially lower, and the measurement does not require professionally skilled attendance.
. An embodiment of the invention will now be described as an example, without limitative manner, having .reference to the drawing, wherein the simple figure dia-,' gramrnatically shows the apparatus fo~ measurement of cavityvolume of soft contact lenses.
The apparatus consists of the vessel 1 for immersion liquid 2, which has on ts bo-ttom 3 a planar or convex, e.g. spherical, suction surface furnished with the hole 4, which is connected with the measuring capillary tube 5 also filled with the same immersion liquid. The measuring capillary tube S is provided with the scale 6, corresponding to the volume of measuring capillary tube 5, which inlet communicates with the broadened inlet chamber 7 placed above the measuring capillary tube 5. The outlet of measuring capillary tube 5 is connected through the broadened outlet chamber 8 with the drain oE measured liquid. A drop of mercury 9 is placed in -the 'broadened inlet chamber 7. The outlet chamber 8 is connected to the unit for pressure variation, which consists of the two-way cock 10, or a set of valves of the analogous function, and serves for connec-ting the outlet chamber 8 either with the overpressure reservoir 11 or with the underpressure drain 1~. .
~ The apparatus is ready for measurement if all its capillary tubings, the measuring capillary tube and the vessel with lens are filled wi-th physiologic saline and the mercury drop 9 is transferred into the broadened inlet chamber 3 by'the flow of solution from the reservoir llo Then, measurement is carried out by closing the cock 10 for shorter time (about half a minute) to allow the mercury drop 9 sit into the upper inlet of measuring capillary tube 5 and the contact lens 14 placed in the vessel 1 perfectly rests on the suction surface of bot-tom 3 of the vessel 1. Then, the capillary is connected with the below - placed drain 12 by turning the two-way cock 10, thus causing the perfect suction of contact lens 14 to the, ' bottom 3 of vessel I by the created underpressure, and the sucked-off volume is indicated by the position of mercury drop 9 in the measuring capillary -tube 5. The sought 'cavity ~olume is then the sum of the indicated volume and the volume assumed by the section cap of bottom 3 of ~7(~[~
vessel 1 covered with the con-tact lens of known diame-ter.
If the bottom is spherical, the cavity volume may be read directly by setting the sliding scale 6, which sits close to the measuring capillary tube 5, by means of the auxilia-ry scale 13 of lens diameter, into such position, that the upper inle-t of measuring eapillary tube is at the volume on the scale 6 corresponding to the volume assumed by spherical cap of -the diameter of measured contaet lens.
Claims (9)
1. Method for measurement of cavity volume of soft contact lenses, wherein a contact lens in a liquid immersion, is allowed freely rest on a planar or convex suction surface and the immersion liquid is then pumped off from the space enclosed between the inner surface of contact lens and the planar or convex surface and its volume is measured.
2. Method according to claim 1, wherein said liquid immersion is water.
3. Method according to claim 1, wherein said liquid immersion is physiologic saline.
4. Method according to claim 1, wherein the sucked-off volume of liquid is indicated by the shift of mercury droplet in a capillary tube, which is closed in the immersion liquid from both sides.
5. Apparatus for measurement of cavity volume of soft contact lenses which consists of a vessel for immersion liquid with a bottom provided with a planar or convex suction surface having a hole, which is connected with a measuring capillary tube also filled with the same immersion liquid, while the measuring capillary tube is provided with a scale corresponding to the volume of measuring capillary tube, which tube is connected, at the inlet, with a broadened inlet chamber placed above the measuring capillary tube, the outlet of said measuring capillary tube being connected by means of a broadened outlet chamber with a drain of measured liquid, while a drop of mercury is placed in the broadened inlet chamber.
6. Apparatus according to claim 5, wherein said suction surface is spherical.
7. Apparatus according to claim 6, wherein the outlet chamber is connected to a unit for pressure variation.
8. Apparatus according to claim 7, wherein the unit for pressure variation consists of a two-way cock or a system of valves with the analogous function, which connects the outlet chamber either with a overpressure reservoir or with an underpressure drain.
9. Apparatus according to claim 5, 7 or 8, where-in the bottom is formed by a spherical surface of radius 12.5 ? 0.5 mm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CS2429/81 | 1981-04-01 | ||
| CS242981A CS223386B1 (en) | 1981-04-01 | 1981-04-01 | Method of measuring the liquids volume according their shift in the specific capillary tube and device for executing the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1170080A true CA1170080A (en) | 1984-07-03 |
Family
ID=5361427
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000400193A Expired CA1170080A (en) | 1981-04-01 | 1982-03-31 | Method for measurement of the cavity volume of soft contact lenses and the apparatus for this measuring method |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5824817A (en) |
| CA (1) | CA1170080A (en) |
| CS (1) | CS223386B1 (en) |
| DE (1) | DE3211986A1 (en) |
| FR (1) | FR2503358A1 (en) |
| GB (1) | GB2096778B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19523768A1 (en) * | 1995-06-29 | 1997-01-02 | Siemens Ag | Device for checking the oil level in electromotive drives with gears |
| DE102009030632C5 (en) * | 2009-06-25 | 2014-12-31 | Benteler Automobiltechnik Gmbh | Method and device for producing a catalyst |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1448753A (en) * | 1964-08-19 | 1966-03-18 | Renault | Hydropneumatic device for measuring volumes |
| DE2128365C3 (en) * | 1971-06-08 | 1974-05-22 | Optische Werke G. Rodenstock, 8000 Muenchen | Device for enlarged representation of the cross section of undestroyed contact lenses or the like |
| JPS554220B2 (en) * | 1972-07-10 | 1980-01-29 | ||
| GB1427118A (en) * | 1974-05-30 | 1976-03-10 | Essilor Int | Apparatus for measuring the frontal power of corneal contact lenses |
| DE2527252C3 (en) * | 1975-06-19 | 1978-07-27 | Helmut 7053 Kernen Hetzel | Storage device for loose, folded sheets of paper with ribbon-like holding elements |
| CS195533B1 (en) * | 1977-09-30 | 1980-02-29 | Otto Wichterle | Measuring set for determination of the sagital depth and average centre curvature of the gel contact lenses |
| DE7828459U1 (en) * | 1978-09-25 | 1979-03-08 | Optische Werke G. Rodenstock, 8000 Muenchen | CONTACT LENS PAD |
-
1981
- 1981-04-01 CS CS242981A patent/CS223386B1/en unknown
-
1982
- 1982-03-25 GB GB8208803A patent/GB2096778B/en not_active Expired
- 1982-03-26 FR FR8205185A patent/FR2503358A1/en active Granted
- 1982-03-31 DE DE19823211986 patent/DE3211986A1/en not_active Ceased
- 1982-03-31 CA CA000400193A patent/CA1170080A/en not_active Expired
- 1982-04-01 JP JP5239682A patent/JPS5824817A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE3211986A1 (en) | 1982-10-21 |
| GB2096778B (en) | 1984-12-05 |
| FR2503358A1 (en) | 1982-10-08 |
| JPS5824817A (en) | 1983-02-14 |
| GB2096778A (en) | 1982-10-20 |
| FR2503358B1 (en) | 1985-02-22 |
| CS223386B1 (en) | 1983-10-28 |
| JPS6319009B2 (en) | 1988-04-21 |
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