A SYSTEM FOR THE DETERMINATION, THE EVALUATION AND THE CONTROL OF THE REFRACTIVE AND ACCOMMODATIVE STATUS OF THE EYE

Abstract: The system for the determination, the evaluation and the control of the refractive and accommodative status of the eye according to the present invention consists of: a scanner (AN) to be placed before the eye optically corrected or not, and completely or partially consisting of material polarizing the optical radiation, and divided into two parts with perpendicular polarization axis; an illuminated target (MR), completely or partially consisting of parts out of polarizing material, having the polarizing axis paralllel or perpendicular to each other, whereby said target may comprise means for moving said parts and for rotating said target onto the longitudinal axis.

Description: "A SYSTEM FOR THE DETERMINATION, THE EVALUATION AND THE CONTROL OF THE REFRACTIVE AND ACCOMMODATIVE STATUS OF THE EYE" The present invention concerns a system for the determination, the evaluation and the voluntary control of the refractive and accommodative status of the eye, comprising a scanner, completely or partially consisting of material having the capacity of polarizing the optical radiations, and a target consisting completely or partially of material having the same polarizing capacities. The uneasiness sometimes linked to the accommodation, i.e. to the power increase of the optic eye system, mainly due to the shape variation of the crystalline lens, is well known, as well as the need of valuating the exerted accommodation and its entity. Also the need of valuating the kind and the entity of the refractive error or ametropia is known, i.e. the surplus or lack of power of the eye, such as not to allow - in conditions of not exerted accommodation - the correct focusing on the retina of the image of a target placed at the optical infinity. A power surplus determines the formation of the image before the retina (myopia), a power lack the formation of the image beyond the retina ( yper etropia) , a difference of power between the two meridians of the optic system causes the formation of two images in the shape of segments perpendicular to each other (astigmatism). The main aim of the present invention is the one of allowing the valuation of the kind and entity of refractive error of the eye, the measuring of the exerted accommodation, the voluntary control of the accommodation and of the reduction or the solution of psychophysical uneasiness and the consequences thereof connected to accommodation. The aim set forth is reached by means of the system for the determination and control of the refractive and accommodative status of the eye according to the present invention, consisting of: - a scanner, through which a target is examined, with the eye optically corrected or not, and completely or partially consisting of material polarizing the optical radiation, and devided into two parts with polarization axis perpendicular or nearly perpendicular to each other. The visual axis of the eye to be examined passes near the separation line between the two polarized half-fields or through the same; a target, completely or partially consisting of parts out of material polarizing the optical radiation, having the polarizing axis parallel or nearly parallel, perpendicular or nearly perpendicular to each other, possibly comprising means for moving said parts and possibly means for rotating all or a part of said target onto the longitudinal axis, so that as the scanner and the target lie on front-parallel planes or on nearly front-parallel planes, and as the scanner is placed, with respect to the target, in such a way that the polarizing axis of the polarized parts of the target is as parallel and/or perpendicular as possible to the polarization axis of each of the polarized parts of said scanner, only the optical radiation, coming from the non-polarized parts and from that parts of the target polarized parallel to the polarization axis of said part of the scanner, passes from one of the polarized parts of the scanner; while the optical radiation coming from those parts of the target polarized perpendicularly to said axis, does not pass or passes in a negligible quantity. Furthermore, the target may be projected onto appropriated screens, like virtual or real screen(s), by means of appropriate means. For what concerns the image seen through the scanner, there are two alternatives in which the polarized parts of the target are seen by contrast with the background: - the polarized parts of the target are on a low luminance backgound, so that the backgound and the polarized part(s) of the target with polarization axis perpendicular to one of the polarized parts of the scanner, seen from said part of the scanner, have a similar luminance, such as to be not, or nearly not, distinguished due to lack or shortage of contrast between target and backgound, while that part(s) of the target with the polarization axis parallel to that of said part of the scanner are seen, through said part, light, i.e. bright, on a dark background, and may be distinguished from the same. A similar process is deserved for the other part of the scanner; - the polarized parts of the target are on a background with an appropriate luminance, sufficient for that the background and the polarized part( s ) of the target, with polarization axis parallel to the one of one of the polarized parts of the scanner, seen from said part of the scanner, have such a similar luminance that they can nearly not be distinguished or can not be distinguished for lack or shortage of contrast between target and background, while the part(s) of the target with the polarization axis perpendicular to that of said part of the scanner are seen, through said part, dark on a light background, i.e. bright and distinguishable from the same. A similar process is deserved to the other part of the scanner. The advantages according to the present invention are, beyond those due to the provided use: - a reduction of the myopia progression due to accommodation and to the accommodative system; - diagnostic action for anomalies of the accommodation and of the accommodation system; - a therapeutic-rehabilitating action for the functional anomalies of the accommodation and of the accommodative system; reduction of the entity of the tonic accommodation; - the distanceing of the remote accommodation point; - to initiate new studies linked to accommodation and to the accommodative system; - measuring of the accommodative power; - to be used in vision training procedure ( s ) ; - valuation and measuring of the ( poss ible ) dif ference between exerted accommodation and accommodative stimulus ; - improvement of the efficiency of accommodation and of the accommodative system; valuation and measuring of the exerted accommodation ; - the pointing out of latent hypermetropia, or of part of it; the activation of psychi -phy s io l ogi c a l process ( es ) related to accommodation and to the accommodation system. The present invention will be described more in detail hereinbelow relating to the enclosed drawings in which some embodiments are shown . Figure 1 shows a scheme of a system for the determination , the evaluation and the control of the refractive and accommodative , static and dynamic status of the eye , according to the present invention. Figures 2 and 3 show the details of a scanner and of a target, with possibility of moving the same. Figure 4 shows the formation of the images with the system according to the present invention. Figure 5 shows an example of an image seen when the image of the target given by the system according to the present invention lies before the retina. The enclosed figures show one of the possible systems, according to the present invention, for the determination, the evaluation and the control of the refractive and accommodative status of the eye, in which the optical radiation coming from the part a of the target MR - polarized in parallel - passes through the part A of the scanner AN, and not through the part B of the same, as it is polarized in perpendicular with respect to the polarization axis of the same, and forms an image a' ; in a similar way the part b of the target forms an image b' . When the power of the optic eye system varies, be the eye corrected or not, and also the distance between the secondary principal plane P' and the retina R, the image of the target may be: - before the retina R (in this case, the parts a' and b' of the image of the target on the retina appear moved to each other); - onto the retina R (in this case, the parts a' and b' of the image of the target onto the retina appear not moved to each other); - beyond the retina R (in this case, the parts a' and b' of the image of the target onto the retina appear moved to each other, and in a sense opposite to the one above described). The position of the image on the retina varies according to many factors , between which the most important are: the distance between target and primary principal plane of the optic eye system, corrected or not; - ametropia of the eye; - eventual exerted accommodation; - eventual optic correction; - spectral composition of the luminance source(s); - possible aberrations, anisotropies , non- homogeneities of the optical media and of the eye. The entity of the moving of the parts a' and b' of the image onto the retina of the parts a and b of the target MR, occurs according to the distance from the retina at which the image of the target is formed, given by the optic eye system. Relating in particular to figures 2, 3, on the scanner AN and on the target MR are shown: - a half-field A of polarizing material; - an axis Y for the polarization of the half-field A; - a half-field B of polarizing material; - an axis X for the polarization of the half-field B; - a line S for separating the half-field A and the half-field B; - a part a of the target, of polarizing material; - an axis Y for polarizing a; - a part b of the target, of polarizing material; - an axis X for polarizing b; - a line S' for separating a and b. It is possible to physically move a with respect to b (or b with respect to a) along a separation line, e.g. on an axis parallel to axis Y, as shown in figure 3B. Furtermore, in figure 4 the following details are shown: I = meeting point between visual axis and target P = primary principal plane P' = secondary principal plane a^ and b^' = images on the retina of a and b when l ' (image of the target given by the optic eye system) is before the retina (1^ P' RP ' ) a^ and b^ = images on the retina of a and b when I' (image of the target given by the optic eye system) is onto the retina ( I _ P ' = RP ' ) a' j and b } = images on the retina of a and b when 1 (image of the target given by the optic eye system) is behind the retina (1^ P ' RP ' ) . For what concerns the functioning of the system according to the present invention, if the distance between target and primary principal plane of the optic eye system, corrected or not; - the possible optic correction; - the spectral composition of the luminance source(s) , and - possible aberrations, anisotropies , non- homogeneities of the optical media and of the eye are placed as fixed, and therefore as parameters, or are fixed, the refraction error of the eye and the possible exerted accommodation remain as variable elements, so that the refractive and/or accommodative status of the eye may be (subjectively) valuated and the entity of the ametropia and/or of the exerted accomodation may be measured, e.g. valuating and measuring the apparent moving of the parts a' and b' , in the example physically moving the parts and and b of the target until the alignment of the parts a' and b' is reached (and thus restoring the shape of the target as if it was seen without scanner); or placing before the eye a lens or lenses of such a power as to reach, as shown in the example, the alignment of parts a' and b' . If accommodation is exerted, it is possible to control if it is exerted in surplus, in the right entity or in shortage with respect to the one requested for focusing at the distance at which the target is placed, furthermore allowing a retroactive voluntary control (by biofeedback) of the exerted accomodation, in the example valuating the alignment or not of the parts a' and b' of the target (and the possible variations of the position between a' and b' - or between b' and a' - in time) . In possible variants of the system according to the present invention, the scanner according to above specification may be provided with a diaphragm or not, may be rotated (on the longitudinal axis) and may be linked or not to optical compensation and may be part of equipments. In further variants, said target may have ot not structural elements (e.g. letters from the alphabet, gratings, etc;) so as to allow the control of the focusing of said target, which in turn may be rotated (on the longitudinal axis).

Claims: CLAIMS 1. A system for the determination, the evaluation and the control of the refractive and accommodative status of the eye, characterized in: - a scanner (AN) to be used examining through it the target (MR) with the eye optically corrected or not, and completely or partially consisting of material polarizing the optical radiation, and devided into two parts with polarization axis perpendicular or nearly perpendicular to each other, whereby he visual axis of the eye to be examined passes near or through the separation line between the two polarized half- fields; - an illuminated target, completely or partially consisting of parts out of material polarizing the optical radiation, having the polarizing axis parallel or nearly parallel, perpendicular or nearly perpendicular to each other, whereby said target may comprise means for moving said parts of polarizing material and possibly a part of the possible non-polarized parts, and means for rotating all or a part of said target onto the longitudinal axis, so that, as the scanner and the target lie on front-parallel planes or on nearly front-parallel planes , and as the scanner is placed, with respect to the target , in such a way that the polarizing axis of the polarized parts of the target is completely parallel or nearly completely parallel , ( or ) completely perpendicular or nearly completely perpendicular , to the polarization axis of each of the polarized parts of said scanner , only the optical radiation , coming from that parts of the target polarized parallel to the polarization axis of said part of the scanner, and from those possible parts of the target that have not been polarized, passes from one of the polarized parts of the scanner ; while the opt i c a l radiation coming from those parts of the target polarized perpendicularly to the polarization axis of said part of the scanner , does not pass or passes in a negligible quantity; and the same process is deserved to the other polarized part of the scanner. A system according to claim 1 , characterized in that the polarized parts of the target are on a low luminance backgound, so that the backgound and the polarized part ( s ) of the target with polarization axis perpendicular to one of the polarized parts of the scanner, seen from said part of the scanner, have a similar luminance, such as to be not, or nearly not, distinguished due to lack or shortage of contrast between target and backgound, while that part(s) of the target with the polarization axis parallel to said part of the scanner are seen, through said part, light, i.e. bright, on a dark background, and may be distinguished from the same; a similar process is deserved for the other part of the scanner. 3. A system according to claim 1, characterized in that the polarized parts of the target are on a background with an appropriate luminance, sufficient for that the background and the polarized part(s) of the target, with polarization axis parallel to the one of one of the polarized parts of the scanner, seen from said part of the scanner, have such a similar luminance that they can nearly not be distinguished or can not be distinguished for lack or shortage of contrast between target and background, while the part(s) of the target with the polarization axis perpendicular to said part of the scanner are seen, through said part, dark on a light background, i.e. bright and distinguishable from 1 (> the same; a similar process is deserved to the other part of the scanner. 4. A system according to claim 1, characterized in that said scanner is provided with a diaphragm. 5. A system according to claim 1, characterized in that said scanner may be rotated on the longitudinal axis. 6. A system according to claim 1, characterized in that said scanner may be linked to optic compensation. 7. A system according to claim 1, characterized in that said target has elements with such a structure as to allow a control of the focusing. 8. A system according to claim 1, characterized in that the target may be projected, with appropriate means, onto appropriate, real or virtual screen(s) . 9. A system according to claim 1, characterized in that the scanner and the target may be parts of eq ipments.

Inventors: VILLANI GHERARDO, VILLANI, GHERARDO
Applicants: VILLANI GHERARDO, VILLANI, GHERARDO
Application year: 1995
Main classification: A61B3
IPC codes: A61B3