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International Newsletter and Forum on Corneal & Scleral Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision
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I-site newsletter is a global newsletter which is purely educational in nature and launched in 2009, that monthly provides independent updates from the international literature on specialty (R)GP lenses and related topics. To unsubscribe at any time, click the link 'SafeUnsubscribe' at the bottom of this newsletter.
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Lets Not Be Rigid About Sclerals
In uncertain times like this, we have the tendency to fall back on certainties. But that is not the reason why this edition of I-site newsletter is mostly devoted to corneal (R)GPs; it is simply because the modality deserves it. Also, to put things a bit in an international perspective, I always have the feeling that I need to promote sclerals outside of North America, as more can be done with them internationally I suppose (in the interest of the patients desiring them), while in North America I feel that we should not forget about other lens modalities too, including corneal (R)GPs. And we should keep in mind that, despite the overload of time and attention toward scleral lenses, corneal (R)GP lenses dominate specialty lens manufacturing. To put some put cash on the barrel: Alexander Levit compared corneal vs scleral (R)GPs in keratoconus patients for his PhD. Alexander is a practitioner from London (UK) who simply asked himself: do I have to switch all of my corneal (R)GP lens wearers to sclerals? See the results of his work based on a publication in Contact Lens & Anterior Eye below. In essence, let's not be rigid about corneal (R)GPs or about sclerals, and let us 'share the road,' as there is room and a need for both of them. But if we want to keep corneal (R)GPs of interest to the new generation of ECPs coming out of school, we may need to revisit (R)GP lens terminology, assessment and fitting techniques and make sure that the value of the modality keeps getting the attention and appreciation it deserves.
Eef van der Worp
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The COVID-19 Pandemic & Contact Lenses
 It has been noted numerous times that contact lens wear does not seem to cause an additional risk with regards to the Corona virus. A point that needs additional attention though, is that we want to prevent an extra burden on the health care system, by preventing contact related adverse events. A focus on fully compliant contact lens wear and especially on modifiable risk factors associated with that is crucial now. Corneal (R)GP lenses have the best track record in this regard. It is also well established that overnight wear of contact lens increases the risk of infections. For our specialty lens wearers, their lens correction is not a luxury or an option. This is the time to inform, instruct and teach our lens wearer about the need for contact lens hygiene - more than ever. See also
GPLI and
SLS websites for specific information on the topic.
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Pauline Cho et al compared the efficacy of cleaning rigid contact lenses using two care solutions with and without rubbing. A one-step hydrogen peroxide solution and a povidone iodine-based solution were evaluated on 64 orthokeratology lenses subsequent to cleaning with rubbing with a surfactant cleaner or without rubbing. Not rubbing and using either hydrogen peroxide or the povidone iodine-based solution is not effective at removing stubborn deposits from orthokeratology lenses, they found. It is essential to rub when cleaning rigid lenses to ensure optimal lens hygiene for ocular health, especially as (R)GP lenses are intended to be reused for at least a year before replacement. Rubbing with a daily cleaner should be included in the instructions for use of the solutions tested for rigid lenses, and practitioners should be encouraged to emphasise the importance of rubbing in lens care. A few years back,
Langis Michaud and Anna Zarouk
looked at the impact on gas-permeable contact lens parameters after storage in a non-neutralized hydrogen peroxide case for 1 to 30 days and found this to be a valid option for rigid lens storage, as lens parameters did not change.
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Is Comfort in Scleral Lenses Better than in (R)GPs?
In a cohort of patients with keratoconus and other ectatic disorders, Alexander Levit conducted a randomized controlled clinical trial. The crossover trial compared outcomes in 34 patients who were randomized to two groups to compare comfort and visual performance of two types of contact lenses: corneal (R)GPs and scleral lenses. Each group was initially fitted with one type of lens, had a 4-week washout period, and then switched to the second type of lens. Subjective comfort scores were significantly higher for participants using scleral lenses versus corneal (R)GPs. The 'take home messages,' according to practiceupdate.com and to Joel Silbert in a reaction to the Levit paper on the website, are that patients wearing scleral lenses had significantly higher subjective comfort scores compared with (R)GP lens wear, but that patients who did achieve good comfort with corneal (R)GPs preferred to stay with them.
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Corneal (R)GP Lens Fit Assessment - Consensus Group
The use of sodium fluorescein (NaFl) dye is still an integral part of corneal (R)GP lens evaluation. But the amount of dye used and the time between application and evaluation are both crucial in the process of consistent assessment of the fit. Jeroen Mulder et al
investigated the effect of NaFl dye on corneal topography and tear surface quality. They found that corneal topography measurements are affected by the insertion of NaFl ocular dye. A single (not double) dose of NaFl resulted in increased reliability and consistency in corneal topography measurements. A 2013 paper initiated by James Wolffsohn looked at
(R)GP lens evaluation and formed a consensus,
which included NaFl lens assessment. The consensus may be due for an update to make it more applicable for the next century - 'beyond 2020'. At the
upcoming NCC meeting - themed 'beyond 2020'
- in September, a new consensus group meeting will be held to look into this. Please let us know if anyone is interested in participating in this group discussion via the e-mail address at the bottom of this newsletter.
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Do Polymer Coatings Affect the Rigid Lens Surface?
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teven Turpin - a Pacific University College of Optometry graduate specializing in cornea and contact lenses and an optometrist working at different practices in the state of Washington (US) - asked colleagues how often they use Hydra-PEG on patients' lenses. The colleagues made the case that every time they ordered lenses with Hydra-PEG, the patients' acuity dropped by about a line. In Steve's own experience, there was not an appreciable difference in acuity whether the lenses were ordered with Hydra-PEG or not. But this begs the question: do polymer coatings affect the lens surface? A recent study by Hasting et al (Optometry & Vision Science, 2020) looked at polymer coatings' changes on the aberrations of conventional and wavefront-guided scleral lenses, which Steve refers to in his Practically Abstract column. The effect of the coating was minimal, according to the study. The average change in higher-order aberrations after coating the lenses equated to a theoretical loss of one letter on the acuity chart. For comparison, there was four times as much variability in aberrations between copies of the same lens design with the same parameters than after coating each lens. The authors did acknowledge that scatter, which was not measured by the instrument, could be a factor that influences lens-on-eye acuity and visual quality. Clinically, applying Hydra-PEG or another polymer coating to sclerals will likely not affect the acuity of the patient, Steve concludes, even on highly customized lenses that correct higher-order aberrations.
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Do you fit contact lenses? As you know, the opportunities and threats for contact lens practice have changed over the years. Contact lens (CL) practice across the world is at critical juncture, with some potential opportunities such as contact lenses for myopia control, multifocal lenses for presbyopia, specialty lenses, etc. and few looming threats such as increasing competition from online business. Anecdotal discussions with eye care professionals have revealed different levels of optimism regarding the future of CL practice. Hence, we wish to conduct this study to understand the views of contact lens practitioners regarding what they perceive as opportunities and threats to CL practice. The findings of this study will help the stakeholders to design targeted strategies to enhance CL practice and address the perceived threats. We would value 5 minutes of your time to report your view. To do so, please click 'next' at the bottom of the site via the 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:
[email protected].
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