Ophthalmic lens
View Patent ↗The invention concerns an ophthalmic lens having a complex surface, with a substantially umbilical meridian and an average sphere progression ranging between 0.50 diopter and 0.75 diopter. The lens is prescribed for esophoric and non-presbyopic users. The lens is prescribed as a standard unifocal lens. Through the presence of the average sphere progression, the user is less adapted to near vision, thus compensating for his/her esophoria.
1. An ophthalmic lens having a prescription for esophoric non-presbyopic wearers and a complex surface, the complex surface having
a substantially umbilic meridian, and
a mean-sphere progression greater than or equal to 0.50 diopters and less than 0.75 diopters.
2. The lens of claim 1 , having a progression length less than or equal to 11 mm, the progression length being defined as the height on the lens between the optical centre and the point on the meridian at which the mean sphere is greater than 85% of the progression to the mean sphere at the optical centre.
3. The lens of claim 1 or 2 , having a maximum mean sphere at a point of the lens corresponding to a 26° lowering of viewing under wearing conditions, relative to the direction of viewing passing through the optical centre.
4. The lens of claim 1 , or 2 , wherein the meridian is rectilinear.
5. The lens of claim 4 , wherein the complex surface is symmetrical relative to the meridian.
6. The lens of claim 5 , wherein the complex surface has a second axis of symmetry perpendicular to the meridian.
7. The lens of claim 1 or 2 , having a mean sphere which is substantially constant on the meridian above the optical centre.
8. The lens of claim 1 or 2 , having a mean sphere which is substantially constant on the meridian below the maximum mean sphere point of the meridian.
9. The lens of claim 7 , having a mean sphere which is substantially constant on the meridian below the maximum mean sphere point of the meridian.
10. A visual device for esophoric non-presbyopic wearers comprising at least one ophthalmic lens having a prescription and a complex surface, the complex surface having
a substantially umbilic meridian, and
a mean-sphere progression greater than or equal to 0.50 diopters and less than 0.75 diopters.
11. A method for fitting an ophthalmic lens in a visual device prescript to esophoric non-presbyopic wearers, the lens having a complex surface with an optical center, the complex surface having a substantially umbilic meridian and a mean-sphere progression greater than or equal to 0.50 diopters and less than 0.75 diopters, the method comprising:
measuring the position in the device of the subject's viewing in far vision, and
fitting of a lens in the device, with the optical centre at the measured position.