Lens system for presbyopes with inter-eye vision disparity limits
A lens system for presbyopes utilizes inter-eye disparity limits to improve vision. The system of lens may be utilized to improve binocular vision when viewing distant, intermediate and near objects by requiring a minimal level of disparity in vision between the eyes wherein the level is not objectionable to the patient. This disparity in vision depends on the lens design for each eye and upon how the lenses are fit in each eye relative to the distance refraction of the patient.
1. A lens system for presbyopes with inter-eye vision disparity limits, the lens system comprising:
a fit guide including lens choices and lens fits relative to the distance refraction for each add need for the lens system; and
a group of lenses including multiple designs, each of the designs having a range of refractive powers, wherein for each lens design choice and fit specified in the fit guide, the visual disparity, Δ , has a lower limit defined by Δ >0.2*add+0.2 and an upper limit defined by Δ <0.7*add+0.5, for an add of less than or equal to 0.75.
2. The lens system according to claim 1 , further comprising constraints on the average binocular distance vision bD and the average binocular near vision bN , wherein hD >−0.2*add+0.6, and bN >−1.3*add+1.2.
3. The lens system according to claim 1 , wherein the group of lenses comprises contact lenses.
4. The lens system according to claim 3 , wherein the contact lenses include single vision contact lenses.
5. The lens system according to claim 3 , wherein the contact lenses include bi-focal contact lenses.
6. The lens system according to claim 3 , wherein the contact lenses include multi-focal contact lenses.
7. The lens system according to claim 3 , wherein the contact lenses include toric contact lenses.
8. The lens system according to claim 3 , wherein the contact lenses include diffractive contact lenses.
9. The lens system according to claim 3 , wherein the contact lenses include continuous asphere contact lenses.
10. The lens system according to claim 3 , wherein the system consists of a toric single vision lens design and a non-toric multifocal lens design.
11. The lens system according to claim 3 , wherein the system consists of a toric single vision lens design and a toric multifocal lens design.
12. The lens system according to claim 1 , wherein the group of lenses comprises intraocular lenses.