DD273771B5 - Method and arrangement for Nahglillenbestimmung - Google Patents

Description

Add = γ- AB (mind.ydpt.) - AB + - ^

characterized in that a lowering of the projectors about an axis, the position of which substantially corresponds to that of the fourth cervical vertebra, in an angular range of up to 25 degrees, the projectors in the nasal direction around the eye rotation points until reaching an angle

, 2aA q = arc cot-pp

be twisted, and the test image with the patient at a distance aT

-Ir = FK -! - + Add aT aA

is presented, which is followed by a shift of the test image to the eye in a known manner for optimal correction.

2. The method according to claim 1, characterized in that during the process at least once the projection systems are adjusted to the eye rotation points vertically and horizontally to compensate for existing Heterophieen each other.

3. The method according to claim 1, characterized in that the detection of the working distance via a measuring tape with integrated encoder, wherein the patient brings a template in the desired working distance.

4. Arrangement for Nahbrillenbestimmung in a refraction system, wherein for each eye a pivoting and tilting projector is provided, characterized in that the eye projectors are tiltable about an axis whose extension substantially intersects the fourth cervical vertebrae of the patient.

For this 1 page drawings

The invention relates to a method and an arrangement for Nahbrillenbestimmung.

It is preferably applicable in so-called "free-standing refraction systems", if, in addition to the lens correction value for the distance, a determination is made of the spectacle lens with which it is optimally viewed in the corresponding working distance.

It is known from the literature that binocular viewing of a real near object causes a convergence ("psychic vergence") through the so-called "consciousness of proximity", which leads to normal binocular single vision.

By contrast, in the case of the "free-standing refraction" method, no real objects (eg a book for the near-sample) but images floating in space are considered.

It is already known, for the purpose of Nahprufung prism compensators in front of the patient's eyes to fold, with the help of which the eyes are forced to a convergence position for looking close. The patient does not tilt his head and is restricted in his field of view by the prism compensators, so that the benefits of "free refraction" are removed.

Furthermore, it is known that the patient must adopt a body posture due to the device's condition, which does not correspond to the natural conditions of a working or reading posture. In the range of the usual working distances, device points which cause the refraction project influence negatively

The determination of the Nahbrille does not work safely, so that often an additional near-sample by means of sample glasses and reading sample is required

From DE Al 3 045 139 a device for subjective and objective refraction determination is known, in which a test character for Nahprufung in the direction of the subjects eyes is moved to a Nahprufentfernung At this distance, the recognition of the test character is only possible with sufficient Akkagmathfahigkeit, which ζ B at Presbyopic persons with insufficient ability to accommodate DD 226 187 has two projectors pivoting and tilting the eye pivot points, which are aligned with the pupils, the pupillary distance being adjustable and readable

The object of the invention is now, in particular in a device for free-standing refraction, to be able to carry out a safe and accurate determination of the proximity of the nose even for presbyopic persons, which is characterized by an optimal simulation of a real near-object

The object is achieved according to the invention by the features of the main claims 1 and 4 Preferred developments are described in the dependent claims

With the invention, for the first time a Nahbrillenbestimmung in a system for "free refraction" safely allows the patient gets a "floating" image in space offered in his natural working distance, where he can take a posture that corresponds to his work or reading attitude Nahsichtbereich no disturbing parts of the device, which can adversely affect the refraction The training corresponds largely to the natural head tilt in activities in Nahsichtbereich With the image of the test image in the Akomodationsbereich the eyes according to the inventive formula the view through the near portion of a real glasses is simulated Therefore, it is possible to carry out a near vision determination Further effects and advantages of the invention are explained in more detail below with reference to the drawings The patient is placed on the device The refraction system consists of a respective projection channel for test characters for the r true and left eye The schematic structure is shown in FIG. 1 A test level 4 is illuminated by a halogen lamp 1 via a collector 2 and a condenser 3. The test 4 is moved via objectives 5 and 7 and deflecting mirrors 6 and 8 to a distance 4 'to the patient's eye A defined change of the distance of the test 4 to the objective 5 causes a change of the distance of the test image 4 'to the eye 9. The test image 4' can thus be imaged in a range of 60 mm to infinity in front of or behind the patient's eye 9

The prerequisite for carrying out the Nahbrillenbestimmung is a correct determination of the far points of both eyes, which is performed in each case monocular For this purpose, the patient is the image of the test 4 'in the far point FP of his eye mapped

FIG. 2 shows the position of the far point and the near point in the case of a) rectangular b) short-sighted c) clear eye. The position of the remote points FP results in the distance correction eyeglasses

Following the measurement of the far point, the accommodation width for each eye is monocularly determined according to the invention. For this purpose, the image of the test 4 'is moved from the far point of the eye to the near point NP of the eye by changing the distance test 4 to the objective 5 The accommodating distances A ₈ (in dpt) is calculated according to

(1) A _B :

J-J-aR aP

aR = distance of the far point to the eye (in meters)

aP = distance of the near point to the eye (in meters)

After the determination of the monocular measured values Far point, accommodation width and near point of the respective eye the binocular determination of the remote correction takes place The patient receives by both projection systems 10,11 test marks offered To reach binocular single vision in the distance, it becomes necessary to compensate possibly existing Heterophoneen To this For example, the projection systems 10, 11 shown in FIG. 3 are adjusted relative to one another about the eye rotation points both in the height and in the side

The axes of rotation 12 and 13 or 14 intersect at the respective eye rotation point of the patient Now the binocular fine adjustment for the distance can take place

The following steps are necessary for the binocular implementation of the near-sample

1 Lowering of the two projectors 10, 11 including forehead system preferably around the patient's cervical vertebra as a fulcrum 15 by 25 degrees (see Figure 4) The patient is forced to a head tilt TB is the scene of the test 4 'for the near-sample

2 Adjustment of Nahkonvergenz by rotating the projectors 10,11 in the nasal direction around the eye rotation points (axes of rotation 13, 14) according to the formula

2aA (2) q = arccot

PD

q - Adjustment angle per projector (in degrees)

aA - desired working distance (in meters)

PD - pupil distance of the patient (in meters)

The PD value is automatically detected. The working distance aA is either entered via a central control panel or automatically detected by a measuring tape with integrated encoder.

For this purpose, the patient gets a blank sheet in his hand to be able to depict the working distance clearly.

3. The near add (in dpt) for the glasses is calculated from the desired working distance aA and the accommodation width AB

(3) Add = 4 AB (at least 4-dpt) -AB + ^ L ·

In this case, one third of the accommodation width, but at least -j dpt, is considered as accommodation reserve.

4. The test image is displayed to the patient at a distance aT (in meters) from:

⁽⁴⁾ 7f = ^FK- aX ^{+ Add}

offered. FK is the distance correction determined in diopters.

Targeted movement of the image determines the optimal correction for proximity.

FIG. 5 shows the near convergence of the patient's eyes.

After approaching the Nahkonvergenz it is possible to rotate the projectors in the vertical and horizontal direction in order to compensate for any existing Nahphorieen can.

All necessary measured values are recorded by microcomputer control via encoders. In a device control computer, the feed values are calculated and retracted by a motor on the refraction device.

The Add value determined by the above procedure is shown in a display and printed in the recipe for the glasses.

Claims (1)

1. A method for Nahbrillenbestimmung in a refraction system with separate, pivotable about the eye fulcrums projectors for each eye, and a displaceable to the patient's eye test image, using the following previously subjectively determined patient values: FK for the remote correction of both patient eyes by monocular imaging of Test images in the respective far point
AB for the accommodation width by shifting the test image from the far point to the near point for each eye PD for the actual value of the pupil distance aA for selected working distances that are characteristic of the activity being performed Add for the close-up value in dioptres, determined with