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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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Rather than focusing on the latest research and future aspects of corneal and scleral lens wear, as we did in the last edition of I-site newsletter, let's in this edition focus on everyday practical issues. Managing scleral lens wear is most probably harder and more challenging than fitting scleral lenses is. And probably the opposite is true for corneal GP lenses: achieving a good fit can be a bit of a challenge (using corneal topography and all), but managing corneal GP lens wear typically isn't that complex. In corneal GPs, there are no tears trapped behind the lens, no fogging, no epithelial bogging, no conjunctival prolapse issues and - oh yes - the microbial keratitis (MK) rate is extremely low in corneal GP lens wear. In fact, it is considered 'the benchmark' for all lens modalities, as it is pretty close to 'no lens wear' at all. And I didn't even mention the potential of IOP increase with sclerals. This is not an attempt to divert from scleral lens fitting: of course, I am a huge fan. It is just to keep things in perspective. The bigger question is, what is the benchmark: sclerals or corneal GPs? Let's see how we can manage scleral lens wear best, while not forgetting about corneal GPs.
Eef van der Worp
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Troubleshooting, Managing, Telemedicining
When looking at scleral lens management webinars, there is actually a whole range of nice offerings.
A good starting point 'to call in' may
actually
be "Scleral Lens Troubleshooting for the Novice Fitter" by Roxana Hemmati, Brooke Messer & Elise Kramer on the Scleral Lens Education Society Student Webinar Platform. Also of interest from the Scleral Lens Education Society (SLS): Managing Scleral Lens Wear by two experts in the field, Karen Lee and Stephen Vincent (presented in March 2020). See the Living Library website (available for members of the SLS). On the GPLI website is Scleral Lens-Induced Complications and Their Management by Dan Fuller (presented in March 2020), which is available on the gpli.info archived webinar website. On a slightly different topic, but one that certainly has relevance to the COVID-times, is an excellent SLS webinar on Telemedicine and Scleral Lens practice with
Clarke Newman, John Gelles and Marcus Noyes. For the latest updates, a continuous series of weblectures is offered by
The SUMMIT
('the Rome meeting'), including lectures on
Conjunctival Mysteries
(Tom Arnold & Melissa Barnett),
A 20/20 Update on Scleral Lens Complication
s (Karen Lee & Maria Walker) and "
The New Normal
" Practicing in the Era of COVID and the new ISO Guidelines (Louise Sclafani & Loretta Szczotka-Flynn). Tough to choose with all of this. You make the call.
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Wettability,
Stability, Inflammatory
In a brand new paper by Walker et al published in Contact Lens & Anterior Eye, Scleral lens wear: Measuring Inflammation in the Fluid Reservoir, fifteen subjects wore scleral lenses for four days, and the inflammatory mediators in the fluid reservoir and basal tears were quantified. This may be the first study to compare the fluid reservoir with the basal ocular surface tears. Inflammatory mediators MMP-9 and MMP-10 were elevated in the fluid reservoir after several hours of scleral lens wear, suggesting potential clinical implications that deserve further investigation. In a paper by Serramito et al in the same journal, Corneal Surface Wettability and Tear Film Stability Before and After Scleral Lens Wear, the anterior surface of scleral contact lenses and ocular surface wettability were evaluated before and after one month of scleral lens wear in keratoconus patients and in patients with intra-corneal rings. After removing the scleral lens, the ocular surface in both groups showed decreased wettability. A potential reason to explain this result could be the osmotic difference between the corneal epithelium and the saline solution used to fill the lens for 8 hours of wear, even inducing corneal epithelium bogging in some cases, which has been seen as a consequence of scleral lens wear.
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Corneal GP Lens Management
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Three and Nine O' Clock Staining
Looking at corneal GP lens management we know that apart from the mentioned fitting challenges and the 'comfort thing,' the only other 'complication' really is 3- and 9-o'clock staining. Sadly though, to our knowledge, not many large studies on corneal GP lens wear management and/or 3- and 9-o'clock staining have been executed in the last decade or so (the decade of scleral lenses). As can be seen via the link below, it is hard to 'solve' 3- and 9-o'clock staining. The only thing we can say is that in our opinion, if we align the corneal GP lens better with the ocular surface, we may be able to reduce it. This is based on two theories. The first is that the corneal GP lens edge 'subtracts tear fluid from the ocular surface.' The tear meniscus height (TMH) during corneal GP lens wearers is low, to that point. And the other issue is that the eyeblink rate, and especially the quality of the eyeblink, goes down. This leads to more tear evaporation and to more exposure in - indeed - the 3- and 9-o' clock positions on the cornea. Both (TMH and eyeblink quality) can be improved by better aligning the lens with the ocular surface. If 3- and 9-o'clock staining is persistent though, there is not all that much we can do. In an irregular cornea case, the choice is pretty easily made then: scleral lenses can surely overcome this, as they bridge and hydrate the entire cornea. There is essentially no room for evaporation and corneal desiccation. There is room however, or should be, for new research in the corneal GP lens field as it looks like this has been 'on hold' pretty much for the last decade.
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Can We Predict Mid-day Foggers in Scleral Lenses?
Mid-day fogging has to be at the top of the list of annoying issues that accompany scleral wear for patients, Steven Turpin writes. Of 248 scleral lens fitters who responded to a question concerning mid-day fogging, 25% reported that their patient had some degree of fogging issues. Unfortunately, the most common fix that practitioners use for this issue is to have patients simply take the lens out and replace the saline before reapplying. There is some great work being done to determine the biochemical source of tear reservoir fogging. Based on a new paper by Schornack et al that Steve refers to, fogging isn't associated with age, sex, race, lens diameter, haptic design, disinfection solution, or filling solution. However, those patients who experience redness and irritation with lens wear were more likely to experience fogging issues. According to Steve, this supports the theory that fogging is due to ocular surface hypoxia/inflammation. See the full practically abstract editorial by Steven 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) - 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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