Arrangement for improving the image field in ophthalmological appliances

p0001The present invention relates to an arrangement with which the image field of the illumination and / or irradiation components of ophthalmological diagnostic and therapeutic devices is improved. The arrangement is particularly suitable for ophthalmological devices in which a consistently high imaging quality is of interest over wide areas of the eye.

p0002This is the case, for example, with gap lamps. A light section is generated by means of slit image projection in the interior of the eye to be examined. In order to ensure an exact evaluation of the cut images thus produced, a sharp image of the slit image is required both on the visual axis and in the edge regions of the eye.

p0003The present arrangement for image field enhancement can in principle be used wherever a consistently high imaging quality is to be ensured over a wide range. Applications include, in addition to ophthalmology, for example, laser medicine, refractive surgery, and irradiation of a light-changeable optical lens according to the patents<patcit id="pcit0001" dnum="WO0041650A"><text>WO 00/41650</text></patcit> and <patcit id="pcit0002" dnum="WO0171411A"><text>WO 01/71411</text></patcit>.

p0004In this type of lens, which consists of a matrix of different plastics, polymerization processes are triggered by irradiation, which cause a change in the refractive index or the shape of the lens. Intraocular lenses (IOL) of this type can be modified after the implantation by targeted irradiation in order to allow defect-reduced vision.

p0005In the case of slit lamps, as described, for example, in [1], mechanical / optical elements, such as slit diaphragms, are predominantly used to generate slit images. The variable and minimum gap widths required for a high optical detail resolution within the optical section are very difficult to achieve. In addition, the adjustment of the mechanical assemblies is very complex, which is made even more difficult by the thermal expansion of the assemblies. A reproducibility of exact gap widths is hardly possible. Since the slit image projection is an optical image with physically limited sharpening depth, the image must always be focused strictly on the location of the examination. A sharp bundle, which is sharp in the whole extent of the human eye, can not be achieved with the solutions mentioned so far.

p0006In the <patcit id="pcit0003" dnum="DE19812050A1"><text>DE 198 12 050 A1</text></patcit> A method and an arrangement for illumination in an eye microscope are described. The most diverse luminous mark geometries are generated by means of opto-electronic components. The light field geometries are thereby projected onto the front or background of the eye and are used for the general examination of the eye.

p0007The <patcit id="pcit0004" dnum="DE19943735A1"><text>DE 199 43 735 A1</text></patcit> Describes a method and a device for the targeted irradiation of an eye by means of light from the visible and / or near-infrared wavelength range. The irradiation causes irreversible chemical changes of the eye-lens substance, which result in a change in the refractive index and / or in the transmission properties for the visible useful radiation, thereby enabling a defect-reduced vision. The successful treatment presupposes as narrowly as possible a full-area determination of the distribution of the refractive power of the eye to be treated. From these values the after Behan are dlung desired refractive power distribution and the necessary data of the radiation detected. As a disadvantage, this solution has the effect that the irradiation can generally take place only one by one in succession, and the treatment process is thereby time-intensive. A fixation of the eyeball is therefore essential for the duration of the treatment.

p0008In the patents <patcit id="pcit0005" dnum="US5404884A"><text>US 5,404,884</text></patcit>; <patcit id="pcit0006" dnum="US5139022A"><text>US 5,139,022</text></patcit> and <patcit id="pcit0007" dnum="US6275718B"><text>US 6,275,718</text></patcit> Methods and arrangements for illuminating the anterior eye segment are described, in which a planar configured laser is used as the light source. A disadvantage of these solutions is the limited variability of the light field geometries. Furthermore, the receiving system for the scattered light from the eye has a physically limited depth of sharpness which can not completely grasp the range of expansion of the sharp laser sectional image.

Literature:

p0009<ol><li>[1] <nplcit id="ncit0001" npl-type="b"><text>Rassow, B. et al., "Ophthalmic Optical Instruments", 1987, Ferdinand Enke Verlag Stuttgart, pp. 99 ff and 137 ff</text></nplcit></li></ol>

p0010In the present ophthalmological apparatus, the straight or even oppositely curved imaging plane of the illumination or irradiation components has a disadvantageous effect. As a result, the structures projected into or onto the eye have only the center of the image field on the visual axis and the required visual acuity on the visual axis. In the outer and marginal areas the fine structures fan out, become blurred and lose significantly in intensity. An evaluation of the distortion of the structures is thereby made more difficult or possible only in a limited range.

p0011The object of the present invention is to improve the image fields of the known illumination and / or irradiation components of ophthalmological diagnostic and therapeutic devices in such a way that structures, images and signs projected onto the eye have a uniformly high imaging quality over wide areas of the eye.

p0012According to the invention, the object is achieved by the features of the independent claims. Preferred further developments and refinements are the subject matter of the dependent claims.

p0013With the presented solution, a uniform image quality can be achieved over wide areas of the eye. Thus, faster and more comprehensive statements are possible in the case of corresponding evaluation algorithms. In particular, the solution is applicable for the determination of the biometric data of an eye, in which large-area curved eye areas with a very fine structure are illuminated.

p0014The invention is described below with reference to an exemplary embodiment. Show this<dl id="dl0001"><dt>FIG. 1:</dt><dd>A schematic illumination beam path with a diffractive optical element (DOE) and the</dd><dt>FIGS. 2 and 3:</dt><dd>Curved, curved planes of the eye.</dd></dl>

p0015In the arrangement for image field improvement in ophthalmological devices, a diffractive optical element (DOE) is arranged in the illumination beam path of the irradiation unit, <b>3</b> Arranged to a targeted shaping of the image plane <b>5</b> to reach. The diffractive optical element<b>3</b> Can be located on the surface of another optical element or, as shown in FIG <figref idrefs="f0001"><b>FIG</b></figref> Can be arranged as a separate element in the beam path. Both the type of light source used and the type of beam shaping, ie, the pattern or pattern generation, are irrelevant (not shown).<figref idrefs="f0001"><b>FIG</b></figref> Therefore shows the beam path outgoing from the respective illumination pattern <b>1.</b> The illuminating beams extend from the lighting pattern <b>1,</b> Via an optical system serving as the first imaging system <b>2</b> to the DOE <b>3.</b> Through the DOE <b>3</b> The beam path of the illumination beams is changed in such a way that in the eye to be irradiated <b>7</b> An image plane adapted to the curvature of the respective element to be irradiated <b>5</b> Is generated. This shows<figref idrefs="f0001"><b>FIG</b></figref> One to the back surface of the ocular lens and <figref idrefs="f0001"><b>FIG</b></figref> A picture plane adapted to the front surface of the cornea <b>5</b>.

p0016Owing to the arrangement according to the invention in the illumination beam path of ophthalmological devices, a spherical, the curvature of the eye <b>7</b> Adapted, image plane <b>5</b> So that the projected characters or structures have a uniformly high imaging quality over wide areas, extending from the optical axis into the peripheral areas of the eye <b>7</b> Respectively.

p0017In another technical embodiment, the diffractive optical element is provided <b>3</b> Pivotable. This allows the effect to be selectively switched on and off. The diffractive optical element<b>3</b> Is thereby optimized in conjunction with the overall system for a defined curvature of the cornea. Correspondingly, other diffractive optical elements are for other corneal curvatures<b>3</b> Which in turn are optimized in conjunction with the overall system for this curvature of the cornea.

p0018Because different DOEs <b>3</b> Are very sensitive to the wavelength, it is advantageous to combine this with corresponding color filters. This allows the wavelength for the DOE<b>3</b> Optimally matched to the therapy wavelength. The optimal DOE can therefore be used for different applications<b>3</b> And combined with the corresponding filter. The filters as well as the DOE<b>3</b> Are advantageously arranged on one or more changeover contacts, such as, for example, slides or wheels. Optionally, the DOE<b>3</b> As well as the filters are used individually or combined with one another.

p0019The arrangement for image field enhancement can additionally have a variable, adjustable, numerical aperture, with which, on the one hand, the intensity of the illumination pattern <b>1</b> In the image plane <b>5</b> And, on the other hand, also the beam density in the eye to be irradiated <b>7</b> Can be influenced to meet the applicable limit values ​​for the radiation dose. In the simplest case, the aperture can be influenced via a variable aperture stop in the illumination beam path.

p0020The arrangement for improving the image field can furthermore have an adjustable focal length or cutting width. Thus, the image position in the target region can be shifted along the optical axis in a defined manner. For example, a sharp image with a high aperture can be placed especially on the lens front surface or lens surface. Intermediate positions are also freely selectable. This displacement possibility can advantageously be combined with a distance control and a focusing aid. Thus, the position can also be precisely adjusted and kept constant along the optical axis. The focusing aid can be performed on the principle of multiple spot imaging under high aperture, so that all individual spots coincide only in the target plane and yield a single spot. The realization of a distance control can, for example, take place via known four-quadrant receivers, which evaluate the apex reflex of the cornea.

p0021The function of the adjustable aperture diaphragm can be combined with the function of the adjustable cutting or focal length and the realization of dynamic pattern advantages in order to specifically apply irradiation sequences with special patterns at specific locations without exceeding the corresponding limit values. All irradiation parameters can be recorded and stored. The position control and correction can be performed by means of an eye tracker unit and ensures an exact irradiation only in the aligned state.

p0022From the spherically curved and generated eye generated by the arrangement according to the invention <b>7</b> adapted image plane <b>5</b> An observation plane also inevitably curved in the eye of the viewer and / or a unit for documenting / archiving results via the observation beam path. By the additional arrangement of one or more diffractive optical elements in the observation beam path, a plane imaging plane can again be generated. This is necessary, for example, for the photographic documentation of the performed diagnosis and therapy as well as their results. As a result, a uniformly high imaging quality can be produced over the entire planar imaging plane.

p0023Since the diffractive optical elements react very sensitively with respect to the wavelength, it is also advantageous to combine these with corresponding color filters. In doing so, the wavelength for the diffractive optical elements should be optimally tuned to an observation wavelength in order to protect the eyes of the observer before the therapy / diagnostic radiation.

p0024The diffractive optical elements can be arranged on the surface of other optical elements or as separate elements in the beam path. The diffractive optical elements in the observation beam path can be pivoted analogously to those in the illumination beam path and can be variable in their wavelength by means of filters. Both the filters and the diffractive optical elements can be arranged on one or more changers, such as, for example, slides or wheels. Optionally, both the diffractive optical elements and the filters can be used individually or combined with one another.

p0025By using diffractive optical elements <b>3</b> In the illumination beam path, optical effects can be achieved which can not be achieved with classical optical components, such as achromats and lenses, or can be achieved only with considerably greater effort. In this case, the image plane of the sparse contour of the eye can be adapted so that the characters and structures projected onto or into the eye have a consistently high imaging quality both in the center and in the edge region.

p0026This is particularly important when lattices or slit structures are projected onto the eye surface for large-area measurements in order to determine the biometric data by a subsequent triangulation.

p0027However, the present invention is also applicable to the generation of variable illumination for diagnosis and therapy in the human eye, in particular for irradiation of the eye lens and other eye sections, such as the cornea or retina. For this purpose, the arrangement for improving the image field can be used in various ophthalmological devices, such as fundus cameras, slit lamps, laser scanners, OPMI devices or also surgical microscopes.

p0028The arrangement can also be used for the irradiation of a lens inserted into an eye or other optically active means. For IOL made of plastic, according to<patcit id="pcit0008" dnum="WO0041650A"><text>WO 00/41650</text></patcit> and or <patcit id="pcit0009" dnum="WO0171411A"><text>WO 01/71411</text></patcit> Irradiation of the lens stimulates polymerization processes which lead to irreversible chemical changes of the lens substance. By means of these processes, the refractive index and / or the transmission behavior for the visible useful radiation or the geometric form of the IOL can be changed in a defined manner and thereby a defect-reduced vision can be made possible.