Method and system for the objective measurement of ocular accommodation
The invention relates to a method and system for the objective measurement of ocular accommodation. A double-pass ophthalmoscopic system is used which incorporates a periscope allowing the patient to binocularly see real objects in an open field and images of the retinal plane to be recorded on a CCD camera. The method includes obtaining, for different values of accommodation stimulation, a set of retinal images corresponding to different focal values in the retina, obtaining the different focal positions in the retina by moving the two lenses incorporated in the ophthalmoscopic system. The image with the best optical quality is obtained for each set of images and by associating the selected image with the known value of the accommodation stimulation it is possible to objectively measure the accommodation.
1. A method for the objective measurement of ocular accommodation, comprising the following steps:
projecting a spot-light beam on the retina of an eye of a patient;
providing an ocular accommodation stimulation to generate an accommodative response;
capturing and recording a series of images resulting from the light reflected in the retina of said spot-light beam in correspondence with the response to said stimulus, with a different focus position of the retina; and
selecting, by processing, an image with the best optical quality from among said series of images, the focus value corresponding to said selected image providing the measurement of ocular accommodation.
2. The method according to claim 1 , wherein said processing is carried out by means of an electronic processing system associated with an image capturing system.
3. The method according to claim 1 , wherein said stimulation is carried out on the ciliary muscles of both eyes of said patient.
4. The method according to claim 1 , wherein said capture is performed on a single eye of the patient and said stimulation is carried out on the ciliary muscles of said single eye.
5. The method according to claim 1 , wherein said stimulation is carried out by means of a negative lens method.
6. The method according to claim 1 , wherein said stimulation is carried out by means of a push-up method.
7. The method according to claim 1 , wherein the mentioned steps, except for the step of stimulating, are carried out by means of using a double-pass ophthalmoscopic system.
8. The method according to claim 7 , wherein said stimulation is carried out by means of a periscopic system including a beam splitter aligned with respect to said spot-light beam and a mirror associated with an object in an open field.
9. A system for the objective measurement of ocular accommodation comprising:
a double-pass ophthalmoscopic system for projecting a spot-light beam on a retina of an eye of a patient and capturing and processing an image resulting from the light which has been reflected in the retina of said spot-light beam
a periscopic system including a beam splitter aligned with respect to said spot-light beam and a mirror associated with an object in an open field;
means providing an accommodation stimulation such that the ciliary muscle of said eye is stimulated through said periscopic system to generate at least one accommodation response;
a Badal device, comprising two lenses and means for varying the distance therebetween to allow obtaining a series of images with different focus values on the retina; and
means for recording and processing said images to select the one with the best optical quality from among them.
10. The system according to claim 9 , wherein said means for stimulation comprise a system for moving said object closer to and away from said mirror of said periscopic system.
11. The system according to claim 9 , wherein said means for stimulation comprise a set of exchangeable lenses of different diopters interposed between the eye of the patient and the object in an open field.