Asymmetrical Multifocal Ocular Implants for Continuous Depth of Field
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multifocal ocular implants often result in discontinuous depth of field between intermediate and near vision when used binocularly, leading to suppressive effects and reduced visual acuity due to significant differences in addition between the two eyes' peaks.
Innovation Solution
A pair of multifocal ocular implants with asymmetrical TFMTF curves, where one implant has a higher TFMTF value in intermediate vision and the other in near vision, ensuring continuous depth of field by combining 'complementary' TFMTF profiles with overlapping values greater than 0.15, and slopes that facilitate smooth transition between vision ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multifocal ocular implants with symmetrical TFMTF curves are used in both eyes, then distance vision and near vision can be addressed, but discontinuous depth of field occurs between intermediate and near vision due to significant differences in addition between the two eyes' peaks
Solution Approach 1:
The patent applies asymmetry by designing the first implant with a TFMTF curve where the rising edge of the asymmetrical peak has a greater mean slope than the falling edge, while the second implant has the opposite configuration. This asymmetrical design allows the peaks to be shifted by greater additions (e.g., 2.00D or 2.50D) without creating discontinuities, thereby maintaining visual acuity continuity and binocular vision comfort across intermediate and near vision ranges.
Solution Approach 2:
The patent implements local quality by creating complementary TFMTF curves where each implant is optimized for specific vision ranges. The first implant has higher TFMTF values in intermediate vision while the second implant has higher TFMTF values in near vision. This localized optimization ensures that each eye contributes optimally to specific depth ranges, achieving continuous depth of field from intermediate to near vision.
2Adaptability or versatility
If implants with larger difference in addition between eyes are used, then greater flexibility in addressing presbyopia is achieved, but suppressive effects increase and visual acuity decreases due to discontinuous depth of field
Solution Approach 1:
The asymmetrical TFMTF curve design enables greater flexibility in presbyopia correction by allowing larger differences in addition between the two implants (e.g., 2.00D or 2.50D shift). The complementary asymmetrical configurations ensure that even with these larger differences, the depth of field remains continuous and visual acuity is maintained above 5/10, eliminating the suppressive effects that would normally occur with such large additions.
3Ease of manufacture
If symmetrical TFMTF curves are used in both eyes, then manufacturing and prescription are simplified, but the depth of field is discontinuous between intermediate and near vision ranges
Solution Approach 1:
The patent resolves this contradiction by introducing asymmetry in the TFMTF curves while maintaining manufacturing feasibility. The asymmetrical peaks are designed with specific slope characteristics (rising edge vs. falling edge) that can be incorporated into standard implant manufacturing processes. This approach maintains depth of field continuity between intermediate and near vision without requiring overly complex custom manufacturing, as the asymmetry is built into the optical design rather than requiring post-manufacturing adjustment.
Solution Approach 2:
The local quality principle allows different regions of the TFMTF curve to be optimized independently. The first implant is optimized with higher TFMTF values in the intermediate vision range, while the second implant is optimized for near vision. This localized optimization creates continuous depth of field while keeping each individual implant design relatively simple and manufacturable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a visual acuity greater than 5/10 across the intermediate to near vision range, reducing the bothersome effect of halos and enhancing binocular vision continuity, while tolerating greater differences between the apices of the peaks.
Implementation Method 1
implants with multifocal optical surfaces (refractive or preferably diffractive)
Implementation Method 2
implants with multifocal optical surfaces (refractive or preferably diffractive)
Data Source
AI summary
An assembly comprising a pair of multifocal ocular implants, wherein each implant has a TFMTF curve, for a pupil of diameter less than or equal to 4 mm, preferably less than 3 mm, having a peak corresponding to the distance vision of the wearer, as well as an asymmetrical peak which spreads between intermediate vision and near vision without discontinuity;for a first implant, the TFMTF value is greater in intermediate vision than that of near vision;for the second implant, the TFMTF value is greater in near vision than that of intermediate vision;the rising edge of the asymmetrical peak of the first implant has, as an absolute value, a mean slope greater than that of its falling edge, whereas the rising edge of the asymmetrical peak of the second implant has, as an absolute value, a mean slope less than that of its falling edge.