As noted in this month’s Quick Poll, 28% of practitioners report measuring tear film osmolarity; the last time we asked this question in June 2013, only 18% of respondents reported measuring tear film osmolarity. Although many in the field recommend its use in managing dry eye disease, it remains relatively low in usage. What do you feel are the barriers to further adoption of measuring tear film osmolarity? Please email us your thoughts at firstname.lastname@example.org.
Jason J. Nichols, OD, MPH, PhD
BlephEx LLC Names Fred Ellis CEO
BlephEx LLC announced Fred Ellis as the company’s new CEO. He comes to BlephEx with more than 29 years of experience with Alcon Novartis. While there, he held numerous positions of increasing responsibility overseeing a wide range of commercial assignments.
MCPHS University School of Optometry Receives Accreditation
After reviewing the report from a March 2018 evaluation visit, the Accreditation Council on Optometric Education (ACOE) voted to raise the classification of the professional optometric degree program at the Massachusetts College of Pharmacy and Health Sciences University School of Optometry to “Accredited.” This classification indicates that the program meets the ACOE standards with no deficiencies or weaknesses that compromise the educational effectiveness of the total program.
I-Med Pharma Inc. Announces Partnership with Medicals International
I-Med Pharma Inc., a Canadian company specializing in dry eye diagnosis and management, signed an exclusive agreement with Medicals International for distribution rights in the Middle East for its patented I-Pen Tear Osmolarity System.
Vision Direct to Offer 24/7 Customer Service
Vision Direct, an online retailer of contact lenses, has expanded its support hours to provide customer service 24 hours a day, seven days a week. According to the company, this will enable customers in the United Kingdom and the United States to receive help at any time when they are ordering products from Vision Direct’s website. Vision Direct’s extended customer service will be run by teams in York and Manchester.
GSLS Accepting Free Paper and Poster Submissions
Free paper and poster topics should include new and innovative concepts on all aspects of contact lenses (such as materials, designs, lens care) in addition to related topics such as corneal and ocular surface disease, diagnosis and treatment approaches, and practice management.
Abstracts for free papers and posters will be accepted until Aug. 31, 2018 at 11:59 pm Eastern Standard Time (EST) and must be submitted online.
The poster competition will be judged in two categories: Clinical and Research. Learn More.
Are you measuring tear osmolarity in clinical practice?
This image shows advanced keratoconus in a patient who underwent radial keratotomy 30 years ago. On the right, he is wearing his original scleral lens with central touch. On the left is my scleral fit, which needed about 200 microns more of elevation. With slit lamp exam, the cornea exhibited good physiological health. He currently wears the lenses 16 hours a day.
We thank Kyriakos Telamitsi 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
Take a Deep Breath—More on Oxygen Transmission with Scleral Lenses
A number of studies and articles have been published over the past few years concerning oxygen transmission with scleral contact lens wear. Concerns for hypoxic sequelae are serious. These works have led to an approach in design and fitting that optimizes oxygen transmission via the use of hyper-Dk materials, minimization of lens thickness, and minimization of retro-lens tear layer thickness.
A recent study was published that evaluated the safety of scleral lens designs in which the authors modeled and clinically assessed central corneal edema induced by scleral-lens wear in healthy subjects.1 Central corneal swelling during scleral-lens wear was measured using optical coherence tomography (OCT). Transport resistances were modeled for oxygen diffusion through the scleral lens and the post-lens tear film (PoLTF) and into the cornea. Oxygen permeability, carbon-dioxide permeability, settled-lens PoLTF thickness, and scleral lens thickness were varied in the calculations to mimic different lens fits.
Results indicated that transport modeling predicts that, for open eyes, increasing PoLTF thickness from 50μm to 400μm increases central corneal swelling by approximately 1% to 1.5% when oxygen Dk/L is greater than 10 hBarrer/cm (i.e., hectoBarrer/cm). Although swelling is greater for oxygen Dk/L < 10 hBarrer/cm, PoLTF thickness has minimal impact in this range. For open eyes, oxygen transmissibility of the lens plays a significant role in corneal edema but is negligible when oxygen Dk/L is > 40 hBarrer/cm. For closed eyes, central corneal swelling is greater than 5% for an oxygen Dk/L range of 0 to 100 hBarrer/cm with typical lens-fitting parameters. For carbon-dioxide transmissibilities ranging between 50 and 250 hBarrer/cm and with a fixed oxygen Dk/L of 25 hBarrer/cm, calculated swelling diminishes by an additional 0.5%. Comparison of model calculations to clinical swelling data is within the error range of the clinical measurements.
The authors concluded that oxygen/metabolite transport calculations for open-eye scleral lens wear show that typical PoLTF thicknesses fitted by clinicians (i.e., PoLTF thicknesses < 400μm) with modern scleral lenses (i.e., oxygen Dk/L > 25 hBarrer/cm) produce corneal swelling of less than 2%. Therefore, scleral lenses prescribed today evoke less swelling compared to physiological hypoxic swelling (i.e., less than 4%) for healthy corneas during open-eye conditions. Closed-eye wear, however, appears clinically unsafe.
Although this study suggests that oxygen transmission is clinically acceptable and would not induce significant corneal swelling unless scleral lenses are worn in closed-eye conditions, we need to keep in mind that there are individual variations that include the impact of lens powers and designs on thickness profiles as well as variability of oxygen demands from patient to patient. Practitioners still should always attempt to maximize oxygen transmission in their scleral lens designs by considering the key parameters that can impact oxygen transmission (lens thickness profile, lens material Dk, and the fitting characteristics that would allow for full corneal clearance but with minimized retro-lens tear layer thickness).
1. Kim YH, Tan B, Lin MC, Radke CJ. Central corneal edema with scleral-lens wear. Curr Eye Res. 2018 Jul 17. [Epub ahead of print]
OCULAR SURFACE UPDATE
Katherine M. Mastrota, MS, OD
Shared Decision Making in OSD
Shared decision making is a key component of patient-centered health care. It is a process in which clinicians and patients work together to make decisions and select tests, treatments, and care plans based on clinical evidence that balances risks and expected outcomes with patient preferences and values. Shared decision making helps providers and patients agree on a health care plan. When patients participate in decision making and understand what they need to do, they are more likely to follow through.1
Thankfully, practitioners have many new diagnostics, therapeutics (both over the counter and prescription), instruments, and treatments aimed at dry eye patients. The course of dry eye therapy is generally chronic, as ocular surface challenges and patient symptoms can wax and wane requiring a dynamic treatment paradigm. Do practitioners query their patients as to with which medications and treatments they would remain compliant? Are patients comfortable with the practitioners’ recommendations? Are patients able to flex with their changing recommendations?
Success in ocular surface disease (OSD) treatment, akin to other disease states, requires a collaborative effort and buy-in from the patient. Watch for continued discussion on shared decision making and decision support tools ahead.
Anterior Eye Surface Changes Following Miniscleral Contact Lens Wear
The purpose of this study was to quantify the effect of short-term mini-scleral contact lens wear on the anterior eye surface of healthy eyes, including the cornea, the corneo-scleral junction, and the sclero-conjunctival area.
Twelve healthy subjects (29.9 ± 5.7 years of age) wore a highly gas-permeable mini-scleral contact lens of 16.5mm diameter during a five-hour period. Corneo-scleral height profilometry was captured before, immediately following, and three hours after lens removal. Topography-based corneo-scleral limbal radius estimates were derived from height measurements. In addition, elevation differences in the corneal and scleral region were calculated with custom-written software. Sclero-conjunctival flattening within different sectors was analyzed.
The authors found that short-term mini-scleral lens wear significantly modifies the anterior eye surface. Significant limbal radius increment (mean ± standard deviation) of 146μm ± 80μm, (p = 0.004), and flattening of –122μm ± 90μm in the sclero-conjunctival area (p < 0.001), were observed immediately following lens removal. These changes did not recede to baseline levels three hours after lens removal. The greatest anterior eye surface flattening was observed in the superior sector. No statistically significant corneal shape change was observed immediately following lens removal or during the recovery period.
The researchers determined that short-term mini-scleral contact lens wear in healthy eyes does not produce significant corneal shape changes measured with profilometry, but it does alter sclero-conjunctival topography. In addition, sclero-conjunctival flattening was not uniformly distributed across the anterior eye.
Consejo A, Behaegel J, Van Hoey M, Wolffsohn JS, Rozema JJ, Iskander DR. Anterior eye surface changes following miniscleral contact lens wear. Cont Lens Anterior Eye. 2018 Jul 3. [Epub ahead of print]