Here’s a quick riddle: What do astrophysicists and eye care scientists have in common?
If you guessed that each pro measures the speed of light and its behavior, you’re correct. If you flagged that each science specifically measures refractive index (RI), you get a giant gold star.
The index of refraction helps measure the speed at which light passes through a medium besides a vacuum. In outer space, light moves through vacuums directly—there’s no dispersion, so it travels at, quite literally, the speed of light. But here on Earth, light has to pass (or, technically, bend) through various mediums, which slows it down. How fast or how slow it moves is its refractive index—which is a critical measurement that optometrists, ophthalmologists, and engineers rely on when developing optical products and assessing patients’ vision. As Henk Weeber, a vision research fellow at Johnson & Johnson, puts it, RI helps determine the “power” level—that is, the amount of vision correction provided by a lens, as well as the materials used to create it.
The eye is a complex organ, that includes the cornea, crystalline lens cortex and nucleus. All these parts have their own RIs—and incur spherical aberrations with age, which can cause optical distortions. These changes to RI and the shape of the crystalline lens in particular sometimes result in more refractive error (aka common eye conditions that make vision blurry). Contact lenses, eyeglasses, laser eye surgery and intraocular lenses (IOL) for cataract surgery are options to provide corrected vision.
Speaking of lenses and glasses: Materials have RIs, too. When it comes to glasses, contacts and IOLs, RI depends on how dense the lens is: the higher the RI, the thinner the lens. Super-high RI levels aren’t always a good thing, though: When RI is too high, the prescription can cause blurry vision and visual irritation, or result in undesirable reflections.
The bottom line: Dictating RI, both when determining a patient’s prescription and when designing a lens, is a delicate process that determines the product’s overall quality and the patient’s satisfaction. Read on for a closer look.
The fact that lenses with higher RI can be thinner is a benefit in both patient comfort and production optimization. Being able to make lenses smaller, thinner, lighter and potentially easier to manufacture is the main benefit of a higher RI.
RI in lens development
The fact that lenses with higher RI can be thinner is a benefit in both patient comfort and production optimization, explains Mike Chemaly, Director of Lens Characterization at Johnson & Johnson. “Being able to make lenses smaller, thinner, lighter and potentially easier to manufacture is the main benefit of a higher RI,” he explains.
Excessively high RI values, however, can also introduce chromatic aberration, or color fringing that occurs when a lens cannot bring all wavelengths of light to a single converging point. In short: it’s a delicate balance. As mentioned above, RI also plays a major role in IOLs. "We make the TECNIS Odyssey™ with a diffractive profile with a very tiny structure on the surface, which is sensitive to any changes in refractive index," Weeber explains.
The TECNIS Odyssey™ IOL surface is designed to eliminate gaps between near, intermediate and far distances[i]†‖ —a feature that Johnson & Johnson engineers say makes it unique when compared to other IOLs. One reportα found that nearly 93% of patients with the TECNIS Odyssey™ lenses don’t need to use glasses at any distance^#[ii], 96% were satisfied with reading on a tablet or smartphone*±[iii], 97% were satisfied with distant vision*±[iv] and 92% of patients could better see steps and street signs at night.*±3
It's very important that the refractive index is consistent, so that you can guarantee you’re giving patients a consistent product that will perform as expected.
Factors that impact RI
Chemaly notes that many high-RI materials tend to be hydrophobic, or water-repellant, which can sometimes complicate balancing moisture requirements in the eye. Still, as he notes, “You don’t want the water content to be very low like it is in an IOL, because that would be uncomfortable to somebody wearing the contact lens.”
Weeber adds that temperature can also impact RI. He says that while typical manufacturing processes for IOLs utilize cryolathing (below zero degrees Celsius), the patient's eye is around 35 degrees Celsius. “The difference in RI between room temperature and 35 degrees Celsius is significant, so we always take that into account when we test our lenses,” Weeber says.
And testing is rigorous: Ensuring uniform lens quality and regulatory compliance is critical when it comes to RI. “It's very important that the refractive index is consistent, so that you can guarantee you’re giving patients a consistent product that will perform as expected,” he explains.
He and his team work hard to ensure lenses fall within optimal RI ranges. “We train all our analysts, including periodic refresher training, and all results they generate are peer-reviewed by other trained analysts and approved by our quality control and quality assurance functions,” he says.
That commitment to success has a direct impact on both patient comfort and positive outcomes, along with utility for eye care professionals—helping pave the way for better vision solutions for people around the world.
Based on pre-clinical bench testing
‖ Continuous 20/25 or better.
α Values rounded to the nearest 1%. Based on 3-month postoperative data from a multicenter, observational clinical study in the U.S.
^ (n=82) 1-month results. Q: “Was the patient wearing any spectacles or contact lenses since the surgery?” Six subjects 6/82 (5 subjects for near, 1 subject for both distance and near)
# Based on 1-month postoperative data from a multicenter, retrospective, real-world clinical study in the U.S. evaluating visual and patient-reported outcomes from subjects bilaterally implanted with TECNIS Odyssey IOL (n=96).
* Values rounded to the nearest 1%.
± Based on 3-month postoperative data from a multicenter, observational clinical study in the U.S. evaluating visual and patient-reported outcomes from subjects bilaterally implanted with TECNIS Odyssey™ IOL (n=33).
Important Information for Contact Lens Wearers: ACUVUE® Contact Lenses are available by prescription only for vision correction. An eye care professional will determine whether contact lenses are right for you. Although rare, serious eye problems can develop while wearing contact lenses. To help avoid these problems, follow the wear and replacement schedule and the lens care instructions provided by your eye doctor. Do not wear contact lenses if you have an eye infection, or experience eye discomfort, excessive tearing, vision changes, redness or other eye problems. If one of these conditions occurs, remove the lens and contact your eye doctor immediately. For more information on proper wear, care and safety, talk to your eye care professional and ask for a Patient Instruction Guide, call 1-800-843-2020, or download the Patient Instruction Guide.
INDICATIONS AND IMPORTANT SAFETY INFORMATION FOR TECNIS ODYSSEY™ IOL WITH TECNIS SIMPLICITY™ DELIVERY SYSTEM, MODEL DRN00V AND TECNIS ODYSSEY™ TORIC II IOL WITH TECNIS SIMPLICITY™ DELIVERY SYSTEM, MODELS DRT150, DRT225, DRT300, DRT375
Rx Only
INDICATIONS:
The TECNIS SIMPLICITY™ Delivery System is used to fold and assist in inserting the TECNIS Odyssey™ IOL, which is indicated for primary implantation for the visual correction of aphakia in adult patients, with less than 1 diopter of pre-existing corneal astigmatism, in whom a cataractous lens has been removed. The TECNIS SIMPLICITY™ Delivery System is used to fold and assist in inserting the TECNIS Odyssey™ Toric II IOLs that are indicated for primary implantation for the visual correction of aphakia and for reduction of refractive astigmatism in adult patients with greater than or equal to 1 diopter of preoperative corneal astigmatism, in whom a cataractous lens has been removed. Compared to an aspheric monofocal lens, the TECNIS Odyssey™ IOLs mitigate the effects of presbyopia by providing improved visual acuity at intermediate and near distances to reduce eyeglass wear, while maintaining comparable distance visual acuity. The lens is intended for capsular bag placement only.
WARNINGS
Intraocular lenses may exacerbate an existing condition, may interfere with diagnosis or treatment of a condition or may pose an unreasonable risk to the eyesight of patients. Patients should have well-defined visual needs and be informed of possible visual effects (such as a perception of halo, starburst or glare around lights), which may be expected in nighttime or poor visibility conditions. Patients may perceive these visual effects as bothersome, which, on rare occasions, may be significant enough for the patient to request removal of the IOL. The physician should carefully weigh the potential risks and benefits for each patient. Patients with a predicted postoperative residual astigmatism greater than 1.0 diopter, with or without a toric lens, may not fully benefit in terms of reducing spectacle wear. Rotation of the
TECNIS Odyssey™ Toric II IOL from its intended axis can reduce its astigmatic correction. Misalignment greater than 30° may increase postoperative refractive cylinder. If necessary, lens repositioning should occur as early as possible, prior to lens encapsulation. The lens and delivery system should be discarded if the lens has been folded within the cartridge for more than 10 minutes. Not doing so may result in the lens being stuck in the cartridge. Do not attempt to disassemble, modify, or alter the delivery system or any of its components, as this can significantly affect the function and/or structural integrity of the design.
PRECAUTIONS
Interpret results with caution when using autorefractors or wavefront aberrometers that utilize infrared light, or when performing a duochrome test. Confirmation of refraction with maximum plus manifest refraction technique is strongly recommended. The ability to perform some eye treatments (e.g., retinal photocoagulation) may be affected by the IOL optical design. The surgeon should target emmetropia, as this lens is designed for optimum visual performance when emmetropia is achieved. The TECNIS Odyssey™ IOLs should not be placed in the ciliary sulcus. Carefully remove all viscoelastic and do not over-inflate the capsular bag at the end of the case. Residual viscoelastic and/or over-inflation of the capsular bag may allow the lens to rotate, causing misalignment of the TECNIS Odyssey™ Toric II IOL. All preoperative surgical parameters are important when choosing a TECNIS Odyssey™ Toric II IOL for implantation, including preoperative keratometric cylinder (magnitude and axis), incision location, the surgeon's estimated surgically induced astigmatism (SIA) and biometry. Variability in any of the preoperative measurements can influence patient outcomes and the effectiveness of treating eyes with lower amounts of preoperative corneal astigmatism. The effectiveness of
TECNIS Odyssey™ Toric II IOLs in reducing postoperative residual astigmatism in patients with preoperative corneal astigmatism < 1.0 diopter has not been demonstrated. Patients with a predicted postoperative astigmatism greater than 1.0 D may not be suitable candidates for implantation with the TECNIS Odyssey™ IOLs, as they may not obtain the benefits of reduced spectacle wear or improved intermediate and near vision seen in patients with lower predicted postoperative astigmatism.
ATTENTION: Reference the Directions for Use for a complete listing of Indications and Important Safety Information.
[1] Data on File. DOF2023CT4023
[2] Data on File. DOF2023CT4051
[3] Data on File. 2024DOF4029
[4] Data on File. 2024DOF4027