Retina Forward Design
Welcome to our continuing series of Credit Educations Courses for Opticians.
This course has been approved for one hour of credit by the American Board of Opticianry. No fee is required for ABO credit.
Learning Outcomes: At the conclusion of this credit education course, participants should be able to:
1. Easily understand and apply Retina Forward Design technology in their practices from a technical, sales, marketing, and dispensing standpoint.
2.Have an in-depth knowledge of how Retina Forward Design is different from other lens designs and how to best work with lenses designed using this technology.
3. Explain Retina Forward Design features and benefits to consumers.
4. Verify lenses created using Retina Forward Design.
Test procedures: Read the article and then click on the "Take The Test" button at the bottom of the page. This will open a new window with a test consisting of 15 questions. To receive ABO continuing education credit, respondents must correctly answer 12 of 15 test questions. Simply click on the best answer for each question and click the submit button at the end of the test. Your test answers will be automatically sent to Seiko Optical and we will send your CEC or notify you of test failure within 7 to 10 business days.
Note: Some states do not accept home study courses for continuing education credit. Check with the licensing board in your state to see if this course qualifies.
Retina Forward Design-A Progressive Lens Technology
Understanding Retina Forward Design and its role in the optical performance of multi-focal lenses
Ever feel like you are in a science fiction movie? New technologies and products enter the optical arena at warp speed. You are bombarded almost daily with information on the latest and greatest in materials, designs, and styles.
This CE takes a look at one of the most advanced technologies in conventional progressives--Retina Forward Design. You will learn how this design optimizes performance by taking vertex distance and pantoscopic tilt into consideration when designing the lens.
Retina Forward Design makes power adjustments that reduce aberrations that are caused by pantoscopic tilt, vertex distance variations, and the distance of objects being viewed. Minimizing these variables means maximizing the patient's visual clarity and comfort.
You will also learn about using adjusted lensometer readings to verify power for a patient's prescription. While these adjusted readings differ from the patient's Rx, they are the key to the patient seeing clearly when looking in different directions through the lens.
If this all sounds like science fiction, it's not. This technology is available today and provides your patient with a great multifocal lens. May the "Force" of Retina Forward Design be with you and your presbyopic patients!
Retina Forward Design uses computerized models of the human eye with analysis of rays from 5,000 points on each lens to produce the best possible imaging at the retina. This process optimizes optical performance in progressive multifocal lenses in several ways, primarily in how people wear their glasses and how that affects the view out of the lenses. There are currently two lens designs utilizing this technology, the AF and AF mini Progressives.
This continuing education course will discuss Retina Forward Design (RFD), its visual and functional features and benefits, how it goes beyond lensometer readings for precise vision, and how to best utilize this technology to grow your progressive addition lens business.
Understanding the Basics
In order to understand this design, it's important to look at the impact that such things as vertex distance, pantoscopic tilt, and swim have on vision.
Vertex distance. The effective power of lenses changes with vertex distance. Increasing vertex distance in plus lenses makes the lenses effectively stronger while making minus lenses effectively weaker. When vertex distance is shortened, minus lenses effectively get stronger, while plus lenses effectively get weaker. Therefore, making lens power compensations for changes in vertex distance is important to maintain the effective overall power of a lens in front of the eye.
Vertex distance also affects field of view. The shorter the vertex distance, the wider the field of view. A shorter vertex distance also enhances the cosmetic appearance of eyewear. Most progressive lenses are designed for fitting with a vertex distance of 12mm to 15mm. This distance provides wide fields of view, a cosmetically pleasing appearance, and adequate separation from the face to prevent wearer's lashes from touching the back surface of the lens.
Pantoscopic tilt. Pantoscopic tilt is the angle between the plane of the lens and frame front and the frontal plane of the face when the superior edge of the lens is farther away from the frontal plane than the inferior edge.
Pantoscopic tilt brings the front of the frame into proper relationship with the wearer's eyebrows and cheeks. It also provides the widest field of view for reading, since the vertex distance of the lower half of the lens is minimized.
However, tilting a lens in front of the eye creates marginal astigmatism. Pantoscopic tilt changes the effective power of the lens and induces cylinder power. Additionally, pantoscopic tilt reduces vertex distance for the lower half of the lens, but increases vertex distance above the 180 degree line.
Swim and sway. Some PAL wearers are dissatisfied with their lenses because they experience a "swim and sway" in their peripheral vision. This is caused by rapid power changes in the periphery of the lenses. Retina Forward Design addresses this by ensuring that power changes from point-to-point on the lens' surface are as smooth as possible.
Using a computerized model of the human eye that simulates actual lens wear, rays from 5,000 points on each lens are analyzed. Using aerospace technology, calculations are made to connect these points to create the smoothest power transitions possible. The technology adjusts the surface power to reduce aberrations.
All aspects of how the lenses are actually worn are considered, including viewing angle, pantoscopic tilt, vertex distance, and object distance. Additionally, lens designers flattened base curves up to 1.5 diopters to create slim, attractive lenses. The goal is improved appearance, comfort, and visual performance.
Features and Benefits
The size, shape, and optical quality of the power zones in a progressive addition lens determine how clear and comfortable the wearer's vision will be when the lens is in the as-worn position. Retina Forward Design means lenses are optimized for the position of wear. Changes in viewing angle, tilt, and vertex distance in different positions of gaze can create optical aberrations which reduce clarity and comfort. This is especially true with aspheric lenses which have flatter curves.
Retina Forward Design lens surface power is precisely calculated on each lens to optimize optical performance and reduce aberrations caused by pantoscopic tilt, vertex distance variations, and object distance.
Correcting these seemingly minor adjustments in power helps improve image quality at the retina in all directions of gaze. This translates into clarity and comfort for the wearer. The technology also provides smooth power changes through surface power optimization with wide viewing areas, creating a natural viewing experience. It allows greater asphericity with uncompromised visual performance and results in a slim, attractive lens.
In plus powers, the flatter curves also reduce unwanted magnification, giving a more natural appearance to the wearer's eyes.
Wear Vs. Readings
Retina Forward Design sharpens images at the retina to deliver clear, comfortable vision in all viewing directions.
The lenses are designed for how the lenses are worn, not how they are analyzed on a lensometer. With conventional PAL design, the accuracy of the lens is determined by placing the lenses on a lensometer to determine if the read powers match the prescribed power.
Lenses using Retina Forward Design technology correct vision when the lens is in its normal position of wear in front of the eye, as opposed to the patient's optical centers being directly in front of the pupil, as in refraction with a phoropter that focuses on what's straight ahead.
In day-to-day life, the wearers look through their lenses in many different directions, not just straight ahead. Retina Forward Design lenses cannot be read properly by conventional lensometry. Lensometer readings on lenses designed using Retina Forward Design technology will differ slightly from the prescribed power.
Lensometer readings on the envelope or job ticket will show the adjusted power, which reduces power error and unwanted cylinder or astigmatism. Two sets of values are printed on the dispenser's portion of the wearer's guide for proper power verification. The first set is the prescribed values for sphere, cylinder, axis, and add power. The second set contains lensometer verification values after optimization by Retina Forward Design.
Here's an example of RFD verification:
Rx Prescribed:
R -4.00 -0.50 x 010 +2.00 add
L -4.00 -0.50 x 170 +2.00 add
Lensometer Verification:
R -4.10 -0.30 x 018 +1.94 -0.63 x 008 add
L -4.10 -0.30 x 162 +1.94 -0.63 x 172 add
Like the design itself, this optimization addresses how eyewear is worn. That is the key to increasing patient satisfaction. The end result will be growing your business in the all-important PAL category as well as keeping the ever-growing market of presbyopic patients happy.
This concludes the article. Click the button below to take the test.