International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision
 October 2015
In This Issue
Column
Myopia Control Practice
Lens Care in (R)GPs
Retinoscopy in Keratoconus
Corneal Dystrophies
I(n)-site-the-practice
Agenda
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Column
Vinyl

I read an interesting article in the International New York Times over the summer titled, 'With vinyl's return, Czech firm has a hit'. It's interesting how an industry that was deemed 'dead' made such a resurgence, and it is so popular and sexy now. Wait - where have I heard this before? Not too long ago, these discussions took place in our industry, too. But as Douglas Benoit writes in Contact Lens Spectrum (see third item in this newsletter), there is no (R)GP demise - although granted, this is largely due to specialty lenses like sclerals, orthokeratology and myopia control. But there is a large group of enthusiastic corneal (R)GP lens fanatics who simply swear by the technology. And why not: like vinyl, surely you can list a number of things that are less ideal, but in the end everybody simply agrees that (R)GPs are the best option out there for the patient. It outperforms in visual quality and is nominated year after year as the safest lens option out there. A brilliant article from the CCLR at the University of Waterloo on soft lens tear film exchange takes corneal (R)GPs as a reference: 'The literature on tear exchange with contact lenses demonstrates conclusively that tear exchange with rigid materials is considerably higher than that which occurs with soft lenses. Good lens mobility on eye is essential and stimulates efficient tear exchange. Deposits, debris and metabolic by-products need to be flushed from the ocular surface in a timely manner, in order to minimize the risk of inflammation. So far, soft lens design innovations intended to enhance tear exchange have not proven clinically feasible and tear exchange values have remained essentially unchanged.' Getting back to vinyl, there even is a Vinyl Revival wikipedia page. Nobody knows where it is going. But I do know it is an honest, best quality product - and it sure has momentum. Just like we see in our industry. 
Eef van der Worp 
Myopic Development
Controlling Myopia

I-site continues its coverage of developments in myopia control with contact lenses in various aspects. 'Choroidal thickness and peripheral myopic defocus during orthokeratology' is the topic of an article in Optometry & Vision Science by Gardner, Walline and Mutti. The purpose of the study was to investigate whether significant thickening occurs in the human choroid in response to chronic peripheral myopic defocus during overnight orthokeratology. The choroid did not show long-term thickening during orthokeratology despite the presence of substantial amounts of peripheral myopic defocus. Apparent inhibition of ocular growth was not attributed to an optical artifact of choroidal thickening, although smaller amounts of thickening or greater biological activity independent of thickening cannot be ruled out, according to the study. Another study by Zhang et al tried a new approach to stop the development of myopia. They evaluated the biomechanical effects of collagen cross-linking by riboflavin/blue light on human sclera and found that the biomechanical strength of human sclera may indeed be enhanced by collagen cross-linking with riboflavin/460 nm blue-light irradiation. An open access paper in Optometry & Vision Science looked into the influence of near tasks on posture in myopic chinese schoolchildren. It was found that close working distances were observed for Chinese myopic schoolchildren. The attention dedicated to each task, the task difficulty, and the page/screen size may affect near working distance and head declination. Handheld video games were associated with the closest working distance, which may be a risk factor for myopia progression, according to previous studies. 
(R)GP Lens Care & Solutions
Proper Care of Modern (R)GP Lenses

In an article in Contact Lens Spectrum, Douglas Benoit writes that over the years, much has been written about the demise of (R)GP contact lenses. Thankfully, such predictions have not come true. If anything, GP lens use is on the rise, although it is a gentle slope. Part of this is due to design changes for multifocal lenses that have increased visual performance and diminished physiologic compromise like corneal molding. Another reason for interest in (R)GP lens use is the redevelopment of scleral lens designs, and along with these design enhancements, material technology has improved as well. We have increased oxygen permeability (Dk) and transmissibility (Dk/t), various refractive indexes, and plasma treatment. But also we have to thank improved care systems that make cleaning and care easier and keep lenses feeling more comfortable. Our care solution choices are better. In addition, the systems, for the most part, are also easier for patients to use. Benoit stresses the importance of reviewing the care of the lenses, as well as the solutions that they are using, whenever patients are in the office. This gives eyecare professionals the opportunity to reinforce the reasons for proper cleaning and disinfection. It also provides the opportunity to ensure that patients are using the correct care solutions. Further, this impresses upon patients that caring for their contact lenses is a serious business designed to allow years of problem-free wear. 
Keratoconus
Retinoscopy in Keratoconus

The aim of a recent study in Contact Lens and Anterior Eye was to evaluate the diagnostic potential of retinoscopy in comparison with Amsler-grading, Pentacam and Ocular Response Analyzer (ORA) in classifying keratoconus stages. Exams were performed on 126 patients. Data of Amsler, retinoscopy, topographic keratoconus classification (TKC) of Pentacam and keratoconus match probability (KMP) of ORA were analyzed. Each of these four techniques classifies keratoconus into stage 0 (normal) to 4 (severe). Descriptive analysis and cross tables were used to compare the different devices. The agreement regarding keratoconus classification was very poor for all the techniques tested. This applies to objective measures as well as clinical classification techniques such as Amsler and retinoscopy. Compared to TKC and KMP, retinoscopy underestimates keratoconus stages, the authors conclude. In contrast, the performance of binary decisions (normal vs. keratoconus) shows a high sensitivity and specificity. Retinoscopy showed a clear clinical use in confirming the diagnosis of keratoconus.
Corneal Dystrophies
Contact Lens Applications in Corneal Dystrophies
 
This review article looks at the application of contact lenses, both soft and rigid, in the care and rehabilitation of challenging corneas. The cornea is precious to sight. Its intricate cellular arrangement and physiology enable it to be transparent and refractive. Corneal dystrophies impact vision at various decades of life depending on the dystrophy at hand. Left untreated, visual ramifications ensue. This review article summarizes the current knowledge of the various corneal dystrophies and the relatively controversial classification based on new genetic knowledge and clinical and histological characteristics. The application of contact lenses, both soft and rigid, has a place in the care and rehabilitation of these unique corneas.
Link Correction
(R)GPs to Induce Peripheral Myopic Defocus
 
Unfortunately, the link to the article in Optometry & Vision Science by Paun� et al mentioned in the August edition of the I-site newsletter was incorrect. Please click below for the correct link to the article abstract.
I(n)-site-the-practice   
Drying & Dyeing
  
Scleral lenses are extraordinary tools in managing ocular surface disease. They provide a unique rigid surface that creates a barrier to the environment while also creating a liquid reservoir that submerges the cornea in constant lubrication or hydration.
A 47-year-old white male diagnosed with chronic graft-versus-host disease (GVHD) complained of extreme dryness, OS greater than OD and worse at night, and intense light sensitivity. He also complained of blur and redness. The severity of his visual blur was associated with the dryness symptoms of his eyes, and severe corneal staining was visible. Past ocular treatments included a course of topical corticosteroid, topical cyclosporine, oral doxycycline and nighttime ocular ointments. Punctal plugs of all four puncta provided minimal relief, and the patient had cauterization of superior and inferior puncta of both eyes. We initiated scleral lens fitting, and after 5 hours of continuous wear with preservative-free saline solution filling the lens, there was no corneal or conjunctival staining.
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I-site is an educational newsletter that is distributed on a monthly basis and provides an update on rigid gas permeable related topics (scientific research, case reports and other publications worldwide). I-site is objective and non-political. Its editor Eef van der Worp, optometrist, PhD, FAAO, FBCLA, FIACLE, FSLS is a lecturer for a variety of industry partners, but is not related to any specific company. Please contact us at: i-site@netherlens.com.