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International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision |
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Plácido (or Javal, no Goode - or is it Gullstrand?)
 At a recent fascinating 'cornea irregolare e lenti a contatto' meeting in Sardinia (Italy) - with nothing but enthusiastic participants, interesting workshops and lectures - one of the organizers, Antonio Calossi, shared a paper with me from the British Journal for the History of Science, which covers, among other historical occurrences, a correspondence between Antonio Plácido, an 'oculist physician' from Portugal, and Emile Javal of Paris, France, who invented the 'topographer.' A fascinating discussion unfolds, with apparent independent discoveries occurring simultaneously. As early as 1670, British scientists were aware of the production of astigmatism by oblique pencils of rays on a spherical lens. The corneal "reflex" had been examined as early as 1619 by Christoph Scheiner, and as a "clinical" test using a candle flame by David Brewster in 1808. An instrument (the keratoscope) for examining the anterior surface of the cornea for the detection of abnormality was first invented by Henry Goode (1847) of Cambridge University in the UK, according to the paper. Antonio Plácido, formerly credited with the invention, independently invented a keratoscope in 1880, the article states. The correspondence of Plácido and Javal reveals that Plácido is now credited with the invention of the photo-keratoscope, formerly attributed to Allvar Gullstrand (1896) of Sweden. Javal is credited with the first description of the application of a photo-keratoscope (independently invented by him) in a specific case of ocular abnormality (a keratoconus). Wow. And we thought things were simpler in the early days. Levene - The British Journal for the History of Science, December 1965 |
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Safety
Orthokeratology lens fitters have been struggling with this question from day one: What is the incidence of corneal infections with the modality and hence, what is the safety? Even if no or limited problems arise in a moderate to large orthokeratology lens practice, the numbers are too small to provide a good view on safety of the whole modality. Mark Bullimore et al, in 2005, aimed at estimating the incidence of microbial keratitis (MK) associated with overnight corneal reshaping contact lenses and to compare rates in children and adults. The results now have been published. Retrospective analysis revealed data of 1317 patients (adults 49% and children 51%) in total representing 2599 patient-years of wear. The overall estimated incidence of MK in orthokeratology is 7.7 per 10,000 years of wear based on that database. The risk of MK with overnight corneal reshaping contact lenses therefore is held similar to that with other overnight lens wearing modalities. Eight events of corneal infiltrates associated with a painful red eye were reported (six in children and two in adults). Two cases of adverse events were classified as MK (both occurred in children) but neither resulted in a loss of visual acuity.
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Partial Reduction with Orthokeratology in High Myopia
Respectively in Contact Lens & Anterior Eye and in Optometry & Vision Science, the experimental design and 2-year follow up results were presented of a study investigating whether the combination of partial reduction orthokeratology with spectacles for residual refractive errors was effective to slow myopia progression. High myopic children (aged 8 to 11 years) with spherical equivalent refraction of at least -5.75D were recruited and randomly assigned into a partial reduction orthokeratology group and a control group. Subjects in the partial reduction orthokeratology group were fitted with custom-made four-zone ortho-k lenses with target reduction of 4.00D. This single-masked randomized study showed that partial reduction orthokeratology effectively slowed myopia progression in the high myopes participating in the study. Axial length elongation was 63% slower in partial reduction orthokeratology-treated children compared with children wearing spectacles.
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Dry Eye as a (Major) Indication for Fitting Scleral Devices
A study from Houston (TX, USA) looked at the indications for PROSE scleral devices in a cohort of 51 patients. The most common reasons for fitting the device were to relieve symptoms of moderate to severe dry eye syndrome (n=25), management of refractive problems (n=23) with keratoconus being the most common (n=14), and to manage other anomalies (n=3). Best-corrected visual acuity improved with the wearing of the PROSE scleral device for both the dry eye group (17 letters) and the refractive group (10 letters). No serious complications were recorded for any of the subjects in this study. Photo: Greg DeNaeyer
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A 28-year-old male patient developed microbial keratitis of his right eye secondary to daily wear of soft lenses that resulted in corneal irregularity and a significant central corneal opacity. Manifest refraction was OD -7.00D 20/30 and OS -6.50D 20/20. The right eye was fit with a large diameter (R)GP lens (diameter 11.5mm), the left eye with a standard (R)GP lens (9.4mm). The patient successfully wears his (R)GP lenses full-time now and is satisfied with both the comfort and the vision (20/25 and 20/20, respectively). Vision in many patients with corneal scarring can be successfully improved by being fit with different kinds of (R)GP lenses.
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Global Specialty Lens Symposium (GSLS) - Las Vegas
GSLS is gearing up for the 2014 edition of its annual 3.5 day meeting that focuses on the latest techniques and technologies for the successful  management of ocular conditions using today's specialty contact lenses. Accredited for continuing education under COPE, NCLE, and JCAHPO, the meeting will offer approximately 30 credit hours - and last year hosted participants from 32 countries. The first day of the symposium hosts special meetings, where topics like Myopia Control, Billing and Coding, the Aging Eye and Scleral Lens Fitting get all the attention they deserve in sessions from 8.30am to 12.30pm. The full GSLS program is available online now; the meeting will be held in the Rio Hotel, Las Vegas (USA).
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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.
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