Bandage contact lenses have been used for many years to protect, comfort, and heal the ocular surface, and there are several lenses that have been cleared by the U.S. Food and Drug Administration for this indication. This past month, we asked about your use of bandage contact lenses, and the results are in. About one-half of you use them infrequently or almost never, and the other half of you use them sometimes to frequently. Admittedly, I was a bit surprise by this, as I would have predicted more practitioners using them less frequently. However, I am happy to see their success in treating patients who need them.
Jason J. Nichols, OD, MPH, PhD
BHVI Launches Evidence-Based Myopia Calculator
A new evidence-based myopia “calculator” developed by the Brien Holden Vision Institute will help support clinicians in communicating and educating patients in managing myopia appropriately. The free web-based tool runs on a range of electronic devices and merges individual patient information with different optical and pharmacological treatment options to illustrate the impact on the future level of myopia.
The tool allows practitioners to input patient age and level of refractive error when beginning therapy as well as to select a treatment option. It then demonstrates the effect of the treatment on myopia progression and how it is likely to progress without treatment. The calculator has been developed as part of the myopia management program being implemented by Brien Holden Vision Institute. You can access the calculator at https://www.brienholdenvision.org/translational-research/myopia/myopia-calculator.html.
Ruben Medal Awarded to Nathan Efron
Australian contact lens researcher and author, Emeritus Professor Nathan Efron, AC, has been awarded the Ruben Medal “for outstanding contributions to contact lens research.” The Ruben Medal is awarded every two years by the International Society for Contact Lens Research. The Society is capped at 100 members who are leaders in the field working in academia, research, clinical practice, and industry. Throughout his career, Professor Efron has undertaken extensive research in the field of contact lenses. He is an opinion leader and has published more than 900 scientific papers, clinical articles, and abstracts as well as eight books. Professor Efron has been invited to speak at more than 500 conferences in 42 countries throughout his career and has won a number of other international research awards and prizes.
Alcon Announces New Opti-Free MPS Packaging in the United States
Alcon has announced that the U.S. Opti-Free multipurpose solution (MPS) packaging will now display a pink sticker to help consumers easily identify the number one doctor recommended brand of MPS, according to Alcon. The new sticker also highlights that Opti-Free products feature an exclusive MPS formula not found in private-label brands. Stickered products are sold at all major U.S. retailers nationwide beginning Aug. 27.
Approximately how frequently do you use a bandage contact lens?
Buddy Russell, COMT, Atlanta
This photo shows the right eye of a 58-year-old female who has a long-standing history of Salzmann’s nodular degeneration OD > OS. Her vision was improved with a scleral lens to 20/25 compared to 20/300 best-corrected spectacle Rx. Notice the small blood vessel leak. She wears her lens comfortably during her waking hours, and the nodule reveals no surface disturbance upon removal of the lens.
We thank Buddy Russell for this image and welcome photo submissions from our other readers! It is easy to submit a photo for consideration for publishing in Contact Lenses Today. Simply visit http://www.cltoday.com/upload/upload.aspx to upload your image. Please include a detailed explanation of the photo and your full name, degree or title, and city/state/country.
S. Barry Eiden, OD
Don’t Just Look in the Center: Importance of Peripheral Oxygen Transmissibility of Contact Lenses
We are all familiar with Dk/t measurement to indicate oxygen transmissibility of contact lenses. These values that are provided by all contact lens manufacturers refer to oxygen transmission at the center of a –3.00D contact lens. The value tells us nothing about oxygen transmission at any other location on the contact lens, nor does it tell us about Dk/t values for other contact lens powers.
A recent study was published that looked at the peripheral oxygen transmissibility (pDk/t) and respective central oxygen transmissibility (cDk/t) in soft contact lenses (SCLs). Additionally, it attempted to determine the values that might preclude SCL-driven corneal neovascularization (NV) in healthy myopic SCL users.
Twenty subjectively successful SCL-wearing patients who presented with asymptomatic but active peripheral corneal NV (not ghost vessels) were recruited as study patients. Twenty-one patients who did not have NV were similarly recruited as controls. Demographic data were collected. Corneal NV was documented and photographed. Current habitual SCLs were collected and thicknesses measured to allow for the calculation of both pDk/t and cDk/t and estimation of local tear oxygen tensions.
No statistical differences between study and control groups in patient age, refraction, or the numbers of years, days per week, or hours per day that patients reported SCL wear were identified. Statistically significant differences were found between the two groups for both pDk/t (P = 0.006) and cDk/t (P = 0.004): mean (±SD) pDk/t was 38.0 ± 23.5 and 19.2 ± 17.7 Fatt units for control and study corneas, respectively. Mean cDk/t values were 80.0 ± 54.4 and 36.8 ± 33 Fatt units for control and study corneas, respectively.1 Peripheral tear oxygen tension that “protected” corneas from vascular filling was more than 84 mmHg.
The authors concluded that maintaining a pDk/t above 30 to 40 Fatt units with daily wear SCLs should protect most normal corneas from NV as a complication of SCL wear. Although this study concentrated on the oxygen transmissibility of soft contact lenses, it serves to remind us of principles that can be applied to all types of contact lenses (soft, corneal GP, hybrid, and scleral). To properly understand the oxygen transmission characteristics of any contact lens, we must consider material oxygen permeability characteristics, lens power, and lens location influences on thickness. With scleral lenses and vaulting hybrids, we additionally need to consider the influence of vault on oxygen availability to the corneal surface. It’s not just Dk/t.
1. Yeung KK, Yang HJ, Nguyen AL, Weissman BA. Critical Contact Lens Oxygen Transmissibility and Tear Lens Oxygen Tension to Preclude Corneal Neovascularization. Eye Contact Lens. 2017 Aug 9. [Epub ahead of print]
OCULAR SURFACE UPDATE
Katherine M. Mastrota, MS, OD
Onion goggles are snug, air-tight glasses that protect the ocular surface from the irritating sulfenic acid that is created when an onion is sliced. Great idea. You can also find swim goggles and Bar-B-Que goggles. Also prudent. But what about goggles to protect against ubiquitous volatile organic compounds (VOCs)?
VOCs are emitted as gases from certain solids or liquids. VOCs are emitted by a wide array of products numbering in the thousands and include household products such as paints, paint strippers, and other solvents; wood preservatives; aerosol sprays; cleansers and disinfectants; moth repellents; and air fresheners. Other possible sources of VOCs are stored fuels and automotive products, hobby supplies, dry-cleaned clothing, and pesticides. Be reminded that products including building materials and furnishings, office equipment (such as copiers and printers), permanent markers, and photographic solutions also emit VOCs.1
VOCs are known to provoke conjunctival, nose, and throat irritation among other symptoms.2 I guess the question is: Should we all be wearing VOC goggles to protect the ocular surface?
Power Profiles in Multifocal Contact Lenses with Variable Multifocal Zone
The power profiles of multifocal contact lenses have been demonstrated to report important information that could be used during the fitting process. The aim of this study is to describe the power profile of a recent set of GP multifocal contact lenses as a function of the pupil radius.
The measured multifocal contact lenses have a center-distance design and are available with five distance-vision diameters (XS, S, M, L, and XL) and two different additions: Type A (up to +2.00D) and Type B (up to +2.50D). The NIMO TR1504 (Lambda-X) was used to obtain the power profile measurements. The optical lens power distribution as a function of the aperture radius was described in terms of radial computed color maps, radial averaged power profiles, addition, and lens portion used for near vision.
The authors found that the amount of total addition achieved depends on the diameter of the distance-vision area. That is, the bigger the distance vision area, the bigger the radius of the lens to achieve the same level of addition. In other words, the XS lens provides higher addition values compared to the XL lens design for a given aperture.
The XS and S designs seem to be aimed to favor near vision, whereas the L and XL designs seem to favor distance vision. For this reason, patients who demand good distance vision might benefit from the L or XL designs, and those who have high demand on near-vision tasks might benefit from the XS or S designs. The M design could be the best option for those patients who have the same needs for distance and near vision.
Monsálvez-Romín D, Domínguez-Vicent A, García-Lázaro S, Esteve-Taboada JJ, Cerviño A. Power profiles in multifocal contact lenses with variable multifocal zone. Clin Exp Optom. 2017 Jul 18. [Epub ahead of print]