GB2408589A

GB2408589A - Position finding device for pupil of the eye

Info

Publication number: GB2408589A
Application number: GB0327700A
Authority: GB
Inventors: David Allen Seaby
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-11-27
Filing date: 2003-11-27
Publication date: 2005-06-01
Also published as: GB0327700D0

Abstract

The device partly comprises a base 2 having a central pinhole 3. To this base is attached a short tube 4, for the purpose of hand holding the device. On the side of the base opposite to the tube are attached adhesive pads 5. The pads may be either discs of double sided tape that have been permanently stuck to the base, or may, for example, be miniature silicone rubber suckers. In use, the customer first dons the new spectacle frames, correctly positioned on the bridge of the nose, then standing, adopts normal head carriage, while looking at an object at eye level about two metres distant. Closing first one eye, then the other, the customer attaches a device, as described above, to each plain glass lens. The device may be slid over the lens until the customers vision through the pin-hole is unimpaired. The holes thus identify the location of each pupil relative to the spectacle frame.

Description

Position finding device for the pupil of the eye This invention relates to

a tool to aid an optometrists find a customer's pupil position relative to each lens in a new spectacle frame.

The most complex lenses used in glasses not only correct a vision defect such as astigmatism, also short or long sight, as well as providing a multi- focal function to enable an older wearer to have equally good distance and reading vision. Such lenses are expensive. It is thus highly desirable there should be no error when positioning them in the chosen spectacle frame.

With multi focal lenses there is an upper part used for distance vision, a middle part used for seeing objects 1-3 meters away and a lower part used for reading. If lenses are not correctly positioned, the glasses will be rejected by the customer or cause problems such as nausea.

At the moment, the art of dispensing the prescription to the customer in the form of usable glasses appears to be behind the science of determining the lens prescription.

For example, the following procedure is typically used to find the position of each of the patient's pupils relative to the lenses in the chosen frames. The patient wearing the chosen frames, but with plain glass in them, is seated opposite the dispenser. The patient looks at the right pupil of the dispenser, while he /she marks the position of the patient's left pupil on the plain glass lens using a marking pen. Then the patient looks at the left pupil of the dispenser while the position of the right pupil is marked.

Provided the patient's carriage, in holding his or her head at its typical angle, is correct, and provided the hand of the dispenser is steady, the correct pupil position will be recorded. However, there are several pitfalls. When sitting, usually with a table between wearer and dispenser, both tend to lean forward to rest on the table. Looking through plain glass at the dispenser's pupil (which will probably not be in focus) the patient tends to peer and may thus lean even further forward. In some cases, where the patient's typical carriage is in any case with head bowed, the correct pupil position will be found, more by luck than by judgement. For the patient who more typically holds his or her head erect, the marked pupil position will usually be too high in the frame. The dispenser may or may not then guesstimate down the original marked position by perhaps as much as 5- lOmm.

To summarise, the difficulties in finding correct pupil position are: firstly, excellent light is needed for the dispenser to see the patient's pupil which may be of varying diameter or shape. Furthermore the wearer may have a squint in one or both eyes. For any of these reasons it may be a guess as to where the centre of the pupil is. Secondly, the patient's pupils may or may not lie on a horizontal line, i.e. one pupil may be lower than the other.

Thirdly, different wearers have pupils that are different widths apart.

Fourthly, the position of the bridge rest in various designs of spectacles may vary relative to the mid depth point of the lens holders. Fifthly, the bridge of the nose, on which the glasses rest, could be almost level with the pupils, or well above it. Sixthly, the habitual carriage of the head of the wearer may be stooped or upright. If the wearer usually walks or sits with head bowed, he or she will predominantly look though the upper half of each lens holder.

However, if someone walks or sits with head erect they will look mainly through the lower half of each frame. Finally, the wearer may habitually hold their head leaning to one side and/or with the head turned to one side.

A device is already manufactured that measures the distance apart of the patient's pupils. In use, the patient looks at a lighted circle in a shallow hand held box that is positioned across the eyes, having a nose pieces to centralize it. The dispenser moves two vertical cross wires in the box, until they are positioned exactly in front of the patient's pupils. The disadvantages of this device are that it is fairly complex, the box is quite heavy and the nose piece comes in contact with a succession of patients' noses. When a patient has a squint it is more difficult to find the pupil position.

According to the present invention there is provided a device that overcomes the problems outlined above. Used correctly, it finds the precise position of each pupil in its frame, including their distance apart. It does not come in contact with the patients face and does not harm frame or lens. It comprises two identical units, one for each frame. Each unit comprises a holding part in the form of a short narrow tube. This is attached centrally to a small, thin oblong of plastic with a central pinhole. Each side of the pinhole, and the opposite side to that of the holding tube, are a number of small lightly adhesive pads. In use, the patient stands with normal carriage, facing a wall, say two metres away, looking at a suitable object on it at approximately eye level. The patient then shuts or masks one eye and moves one of the units about in front of the open eye until the object is clearly visible through the pin hole. The lightweight device is then pressed against the lens so that it attaches to the lens by virtue of the adhesive. This is repeated for the other eye. The patient should then still be able to see the object just as clearly as originally, but it should now appear centrally in a single circular shadow.

Normal head carriage should have been maintained, and this should be checked. Removing the glasses with the two units attached, the dispenser can now measure the exact position of each pupil, both their distance apart and the distances from the top of each *ame. If there is any doubt, for example, if one pupil appears lower than the other, the procedure can be quickly repeated and a check set of measurements thus obtained.

In the case of a patient who is very short sighted, and consequently cannot see the test object, a small cap is fitted to each tube. Each cap contains a concave lens to approximately correct this myopic vision deficiency.

A specific embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which: figure 1 shows the device in plan view, as if adhering to a spectacle lens, figure 2 shows the device attached to a spectacle lens in side view.

Referring to the drawings, in figure 1, the device is shown in plan view attached to a lens 1. In figure 2 it is shown in sectional view, attached to a lens 1. The device partly comprises a thin flexible oblong of plastic 2. This is referred to as the base. It is, for example, 20mm x 35mm with a central pinhole 3, approximately 3-4mm in diameter. To this base is attached a short tube 4. This is, for example, 18mm wide and 10mm long. On the base's opposite side to the tube are attached adhesive pads 5. These are shown as four dotted circles approximately 5mm in diameter. Such pads may be any one of several different types, for example, discs of double sided tape that have been permanently stuck to the base, or strips of double sided tape stuck to the base, or miniature silicone rubber suckers, or, at a future date, pads similar to those used by gecko lizards employing molecular adhesion.

Claims

- Clams

1. A small light-weight tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, comprising a base with a pin hole in it, a means of hand-holding the base, for example a short tube attached centrally to one side of it and means of temporarily attaching the whole device to a spectacle lens by, for example, means of one or more adhesive pads attached to the opposite side of the base to that of the hand held tube.

2. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame as in claim 1. In which, for example, the base is a thin flexible rectangle of plastic, approximately 35-40mm x 20mm, with a central pinhole 3-4mm in diameter.

3. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, as in claims 1 and 2. In which, for example, the holder for the base is a short plastic tube lOmm long and 18mm in diameter with a wall thickness of 2-4mm.

4. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, as in claims 1-3 in which, for example, the base has 4 slightly adhesive pads, approximately Smm in diameter, for the purpose of temporarily attaching the device to a lens in a spectacle frame.

5. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, as in claims 1-4, in which the adhesive pads are discs of double sided plastic tape 'Super glued' to the base.

6. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, as in claims 1-4, in which there is a single large adhesive pad covering and stuck to the whole side of the base, or just either side of the pin hole.

Claims

7. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, as in claimsl-4, in which the adhesive pads are in the form of several tiny silicone-rubber suction cups.

8. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, as in claim 1-4, in which the adhesive pads resemble those used by geckos, employing molecular forces to obtain adhesion.

9. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, as in claim 7, in which, for example, the entire device, including suction cups is moulded from silicone rubber, or similar soft flexible material.

10. A small, light-weight, tool for 'marking' the wearer's pupil position on a spectacle lens relative to its frame, as in claims 1-9 in which the tube part retains a plastic lens or has means to retain a lens, by for example capping it with a cap that holds a lens.

1 1. A set, comprising a minimum of two devices, as described in any of the claims 1-10, possibly with several caps retaining lens, as outlined in claim 10, the whole being in a custom made box ready for use.