JPS5824817A - Method and device for measuring volume of cavity of soft contact lens - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the cavity volume of a soft contact lens and an apparatus for carrying out the method.

When selecting soft contact lenses, it is necessary to examine the shape of the subject's eyes and make the correct choice according to the test results. Conventionally, the following methods have been used to characterize shapes. That is, (1) move the needle to the center of a lens whose peripheral portion is freely movable on a flat table surface until it reaches the inner top of the lens; The sagittal depth of the lens determined in this way, together with the actual measured diameter of the lens, provides a rough guide to the total convexity of the lens.

(2) Similarly, slide the needle into a lens placed symmetrically on a circular edge of arbitrary diameter, thus measuring the average curvature of the lens above said diameter.

(3) A cell is filled with an immersion liquid, a lens is placed in the cell in a freely movable manner, and the lens is measured using a projection or photography device.

(4) Measure a lens with no moisture on its surface by the reflection method to determine its inner dimensions or the entire course of its outer curved surface.

However, among the above methods, (1), (2)
, (4) is accompanied by an error caused by the deformation of the soft lens due to gravity. Furthermore, such measurements are completely impossible with ultra-thin lenses.

Method (3) is reliable in measuring the lens shape because the lens is immersed in liquid, so the deforming force described above is not applied to the lens, but it is difficult to form an image to assess projection. The method is extremely complicated because it requires more precise measurement.

In addition to this, strong reflections of tangentially illuminated surfaces occur during lateral projection, making reliable measurements of internal surfaces impossible. When wearing contact lenses, this inner surface
Since its outer surface is much more important, this method (3)
is also not satisfactory.

The above conventional methods are overcome by the method of measuring the cavity volume of soft contact lenses of the present invention, which includes:
The method of the present invention involves placing a contact lens freely in an immersion liquid, preferably water or saline, on a planar or convex surface, and connecting the inner surface of the contact lens with a planar or convex suction surface. It is characterized by excluding the immersion liquid in the interspace and measuring the weight of that liquid, which is a characteristic constant of the contact. Preferably, the amount of adsorbed liquid is expressed by the movement of a column of mercury sealed from both sides by the measured liquid in the capillary tube. For this purpose, the initial position of the mercury drop may be easily adjusted by widening the capillary tube upwards at at least one of its ends. The end position of the mercury drop at one or both ends of the capillary expands the inner diameter of the capillary upward at that end,
The mercury is fixed because it reaches a chamber with multiple internal diameters, so the mercury will not be swept away even if the liquid flow is strong. When the fluid flow stops, the mercury collects in a bead shape at the widened inlet of the chamber, clearly closing the capillary tube. When the liquid flows back, the mercury drop moves as a short column along the measuring capillary. At the same time, mercury is strongly pressed against the wall of the capillary due to its high surface tension, so that at the location of the mercury drop, only a very thin film of liquid remains on the wall, and the space in the capillary is very precisely covered by the mercury drop. be divided. The pressure that presses the mercury droplet is inversely proportional to the capillary diameter according to the equation below.

p=Q, 0153/d (kg/m2) where p is the pressure and d is the inner diameter of the capillary (■).

First, if the thickness of the thin film of liquid that adheres to the wall of the capillary at the point where the mercury drop passes through is inversely proportional to the pressure exerted by the mercury drop on the wall, then the amount of liquid that can be moved through the capillary and the amount of the adhered film of liquid are It can be concluded that the ratio of

As will be seen, in the method of the present invention, the accuracy of the actual volume measurement is ensured even when a very thin capillary tube is used, so that even very small amounts of liquid can be precisely measured.

It has been found that only a small amount of negative pressure, ie, on the order of 2 to 10 6 n water, is required to fully adsorb the soft lens to a suitably chosen surface.

At negative pressure with maximum thickness lens, e.g. aphakie
It can also be held with KS lenses.

As is clear from this, the measurement method of the present invention has advantages. Measuring the suction displacement using a piston or a corrugated box has a large error because overcoming mechanical resistance requires a force greater than the minimum force required for suction. In addition to this, the measurement accuracy of the adsorbed liquid is 1ffl+1.
13 is required, so the mechanical parts require high precision.

Numerous methods and corresponding devices have been developed for the precise measurement of very small volumes of liquid, for example for volumetric microanalysis with automatic setting of the zero position in the measuring tube. Apart from mechanically controlled piston devices, which always require high precision and are therefore relatively costly, a number of so-called automatic microbiulets have been developed. In these microbiulet, the liquid level setting in the measuring tube is mainly carried out by means of hydrostatic devices, which allow the liquid above the zero level to flow out of the oat flow, or by means of a fixed narrow auxiliary immersed at a precise depth. This is done by adsorbing the liquid through a capillary tube. A disadvantage of these devices is the non-uniform shape of the meniscus of the small diameter tube, which results in differences in zero setting as a result of varying wetting of the wall by the liquid.

Another object of the invention consists of a container for an immersion liquid, the bottom of which is preferably planar or convex with a hole connected to a measuring capillary which is also filled with the immersion liquid. An object of the present invention is to provide an apparatus for carrying out the method of the present invention, which has a spherical suction surface. The measuring capillary is graduated according to its volume and is connected at its inlet with an enlarged inlet chamber located above. The outlet of the measuring capillary is connected through a wide outlet chamber with the outlet of the measured liquid, and the mercury droplet is contained in the wide input chamber. Deguchi Chan/
? is preferably connected to a device that changes the pressure.

Preferably, this pressure change device comprises a three-way cock, or a valve system with a similar function, connecting the outlet chamber to either a positive pressure tank or a negative pressure drain.

It is particularly advantageous to utilize a spherical suction surface with a radius of 12.5 m. This suction surface has a diameter of 13.51+J14.5 and these diameters are centered on the same tangent as the average eye on the same diameter. The difference between the volume of an average eye section cap and the volume of a spherical cap of the same width and radius of 12.5 mm is therefore practically constant (67
am'). The initial position of the mercury drop in the capillary is 16 on the scale.
If the linear volume scale is set to point to 71+II++3, the position of the mercury drop after adsorption on the lens will be the cavity volume of the lens, the volume of the average axial segment of the eye with the same radius,
In other words, it directly shows the difference in so-called adsorption volume that allows a lens to be adsorbed to an average eye. 13.5 to 1 of the subject's eyes
4.4.If the subject's eye is measured such that the volumetric deviation of an axial segment of 5 bait widths from an average eye segment of the same width is obtained from the obtained no. A direct comparison may be made with the measured volumetric deviation of the lens from the same average eye. In this way, it is possible to objectively confirm which suction volume is appropriate for attaching the lens to be measured to the examined eye.

The amount of liquid adsorbed and removed is relatively small, about 10 microliters. If a measurement accuracy of about 10 microlitres is required and the scale must be read with the same precision on the order of 1 d of mercury droplet with the ridge eye without using a magnifying glass or catetometer, the internal diameter of the capillary tube should be about 1 cm or more. must not. On the other hand, very small diameters cannot be used because of the reduced visibility of the water column and the risk of increased errors due to irregular or irreproducible wetting of the capillary wall.

According to experience, the optimal capillary inner diameter is between 0.5 and 2 Ill.
It is I11.

It is essential that the capillary material be transparent or at least translucent.

Glass capillaries are clearly the best. On the other hand, in the case of measurement, the container is also used! U! It is easier to use a capillary tube that simultaneously makes the connection to the control pneumatic device.

Capillaries made of relatively soft materials, such as glassy vinyl chloride or silicone rubber, may be used since pressure changes within the system are minimal.

The position of the measuring capillary has no effect on the measurement accuracy. Therefore, the position of the capillary tube may be vertical, horizontal or inclined.

Compared to the prior art, the inventive step of the present invention is that even very thin contact lenses can be measured quickly and reliably, which is faster and requires substantially less investment than known methods. and does not require professionally skilled personnel.

The invention will now be explained in more detail with reference to the accompanying drawings, which show an apparatus for measuring the cavity volume of soft contact lenses.

The device comprises a container 1 to 9 for an immersion liquid 2, the bottom 3 of which is provided with a planar or convex, e.g. It has a hole 4 connected to a capillary tube 5. This measuring capillary tube 5 is provided with a scale 6 corresponding to its volume.
The entrance of this capillary tube communicates with a wide entrance chamber 7 located above the capillary tube 5. The outlet of the capillary tube 5 is connected to a discharge port (drain) of the measured liquid through a drainage chamber 8. A mercury droplet 9 is contained in a floor-filled chamber 7. The outlet chamber 8 is connected to a pressure change device, which may be a three-way cock JO or a set of valves with similar functionality, an outlet to either a positive pressure tank or a negative pressure drain. It serves to connect the chamber 8.

The device takes measurements once the capillary tube, the measuring capillary tube and the container containing the lens are all filled with physiological saline and the mercury drop 9 is transferred into the bed-filled lochamper 7 by a relentless flow from the tank 11. It's ready. Next, cook 1
0 is closed for a short period of time (approximately half) to allow the water droplet 9 to enter the upper inlet of the measurement capillary 5,
Further, the contact lens 14 contained in the container 1 is completely locked on the suction surface of the bottom 3 of the container 1. Next, the capillary tube is connected to the three-way cock 1 (lower drain by turning) 2, and the negative pressure contact lens 14 thus generated is completely adsorbed to the bottom 3 of the container 1, and the amount absorbed and removed is It is indicated by the position of the mercury drop 9 in the measurement capillary 5.The cavity volume determined at this time is determined by the finger (1).The indicated volume and the container 1 covered with a contact lens of known diameter are
is the sum of the volume occupied by the bottom 3 section cap. If the bottom is spherical, the cavity volume can be calculated using the auxiliary scale 13 of the lens diameter, and the slide graduation (scale) 6 located on the measuring capillary 5, so that the upper entrance of the measuring capillary is the diameter of the contact lens to be measured. Direct reading is possible by setting the scale 6 at a position corresponding to the volume occupied by the spherical cap.

[Brief explanation of the drawing]

The accompanying drawing is a schematic diagram of an apparatus for measuring cavity volume of soft contact lenses of the present invention. 1... Container, 2... Immersion liquid, 3... Container bottom,
4... Hole, 5... Measuring capillary, 6... Scale, 7
...Rochampa on the floor, 8...Rochampa with a crowd, 9.
...Mercury drop, 10...Three-way cock, 12...Negative pressure drain. Margin below (12) Procedural amendment (method) September 10, 1980 Commissioner of the Japan Patent Office Wakasugi O [1 husband] 1, Indication of the case 1981 Patent application No. 052396 2, Name of the invention Cavity of soft contact lens Method and device for adding up volumes 3, Relationship with the case of the person making the amendment Name of patent applicant: Czeskoslovenska Academy Bet 4, Agent, (3 others) 5. Date of amendment order, s. ,, ,,
, , , . 7. 1. 1 letter

Claims (1)

[Claims] 1. A lens immersed in an immersion liquid, preferably water or physiological saline, is placed freely on a flat or convex suction surface, and the immersion liquid is then applied to the contact lens. A soft contact lens cavity volume measuring method characterized by removing from the inner surface and a planar or convex surface of the soft contact lens and measuring the amount of removal. 2. The method according to claim 1, characterized in that the amount of adsorption and removal of the liquid is determined by the movement of mercury droplets in a capillary tube confined in the immersion liquid from both sides. 3. The bottom (3) of the container (1) for the immersion liquid (2) or from the container (1) is provided with a flat or convex, preferably spherical suction surface. , and υ have a hole (4) connected to a measuring capillary (5) filled with the same immersion liquid, and the measuring capillary (5) has a scale (6) corresponding to its volume. This capillary has an inlet section located above the capillary (5).
<7>, and the outlet section is connected to the drain of the measured liquid through the inflow chamber (8), respectively, and the mercury droplet (9) is contained in the above-mentioned floor chamber chamber (7). A device for measuring the cavity volume of a soft contact lens. 4. The device according to claim 3, characterized in that the outlet chamber (8) is connected to a pressure change device. 5. The pressure change device is characterized by consisting of a three-way cock 01 or a valve system with a similar function, which is connected to either the outlet chamber (8) for positive pressure (01) or the negative pressure drain (01). An apparatus according to claim 4. Claim 3.4, characterized in that the 6° bottom (3) is formed of a spherical surface with a radius of 12.5±0.5 m.
．． Apparatus according to any of clause 5. Margin below