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International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision |
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Growing (Up)
 To visualize the growth of scleral lenses in the market, we can simply look at graphs showing the increase of lens fits over the last 5 years - as recently shown at the fantastic annual EFCLIN meeting in Portugal. In all major geographical regions an obvious growth can be seen: in fact a more than linear increase. At the same time, the state of the scleral lens modality may be best described by a remark made at one of the receptions by a young eyecare professional from the Netherlands who fits a lot of scleral lenses. 'Scleral lens patients,' he said, 'are getting more and more critical.' They demand excellent vision, even front toric optics to further optimize their vision - and slight discomfort is hardly tolerated anymore. Scleral lens wearers are almost becoming like regular patients. I know there are still many questions to be answered regarding the scleral lens modality. But this remark, which was echoed by others, begs us to think: is the scleral lens growing up? Eef van der Worp |
Hyperopic Orthokeratology
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Serving the Emmetropic Presbyope
The April edition of Optometry & Vision Science hosted a number of very interesting articles relevant to our industry. One of them is the 'editors choice' of the April edition (with free access for everyone): a paper by Paul Gifford and Helen Swarbrick showing that orthokeratology for monovision is a viable option for presbyopia correction.
The study showed that the monocular near visual acuity improved significantly, while the binocular distance visual acuity did not change from baseline in emmetropic presbyopes. More on the topic of corneal reshaping will be covered at the orthokeratology meeting EurOK in Brussels (BE).
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Classifying the Cone
Two papers in the April edition of Optometry & Vision Science attempt to classify keratoconus. Jason Marsack et al achieved this by looking at higher-order aberrations. Of all (111) eyes, 81% could be categorized into five subgroups, with different types of COMA as the main variable of these subgroups. Dario Ramos-Lopez et al from Spain looked at screening of subclinical keratoconus with Placido-based corneal indices. A total of 124 eyes were analyzed by evaluating the direct digitized images of the Placido mires projected onto the cornea. This method proved to be effective in distinguishing between normal eyes (50 eyes), keratoconic eyes (50 eyes) and keratoconus suspects (24 eyes). The system excelled in simplicity and sensitivity in detecting the irregular cornea, and it may be used as supplementary criteria for diagnosing and grading subclinical keratoconus, according to the paper. Loretta Szczotka-Flynn looks at 'Detecting Keratoconus Early,' taking the posterior cornea into account, in the April edition of Contact Lens Spectrum.
Ramos-Lopez et al - Optometry & Vision Science, April 2013
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Diagnostic Fitting
At the European Academy of Optometry & Optics meeting in Malaga (Spain), Sarah Ortiz et al from the school of optometry at the University of Valladolid in Spain presented a poster on the number of diagnostic lenses needed and the number visits required to obtain a successful lens fit between normal (R)GP and keratoconus patients. Interestingly, they found little difference between the normal (R)GP lens group and the keratoconus lens group for both the number of diagnostic lenses used and the number of patient visits.
Sara Ortiz et al, EAOO 2013
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Front Seat in Seattle
 A number of (R)GP lens-related posters and papers were presented at the ARVO 2013 meeting. Regarding scleral lenses, Cherie Nau and Muriel Shornack (poster #5469) found that within two hours of placing a 15-mm scleral lens, the central clearance between the posterior lens surface and the cornea decreases significantly. Scleral lens clearance after initial placement of the lens was 165 microns on average; after two hours of lens wear, the clearance was reduced to an average of 80 microns. Similar results on scleral lens settling were reported by Patrick Caroline and Mark Andre in the May 2012 edition of Contact Lens Spectrum. Jason Marsack et al (poster #5466) looked at correcting higher-order aberrations in keratoconic eyes with scleral lenses and concluded that visual acuity gain is achievable, but also that it is highly subject-dependent. A poster by Yue Liu (#5471) reported on the use of custom-made orthokeratology lenses in guinea pigs based on OCT height data, with promising results regarding corneal reshaping outcomes of up to 6D and significantly reduced frequency of lens ordering, according to the authors.
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Presbyopia- A Simultaneous Solution
Correcting presbyopia with a simultaneous system can provide some benefits for your patient compared to translating (R)GP designs, including meeting reading demands in more positions of gaze, better comfort and improved intermediate vision for computer use. Due to the fact that several corrections are presented to the brain, contrast vision will be decreased. To improve contrast vision, first reduce the near addition on the dominant eye - sometimes to the point of providing only distance correction for that eye. Second, change the zone diameter depending on the vision demand preferred. Finally, change the design from distance center (DC) to near center (NC). For more: see link below.
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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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