June 2023
Column
Ode to Scleral Lenses
Artificial intellegence (AI) is 'hot,' and 2023 may go into the history books as THE year that AI came into our lives and manifested itself, whether in art, music or the written word; it seems to be present everywhere suddenly. See also Jason Nichols’ column in the April 23rd CLToday. The theme of the previous edition of I-site newsletter was 'an ode to ocular surface shape topography', and this inspired a reader of I-site newsletter, Jenya Davelman from Jerusalem (Israel), to ask Chat-GPT to write an ode to scleral lenses, literally using those words. You will be amazed! See the full 'ode' via the link (PDF) and a snapshot here below. I’m not sure what could have said it better than this ode to this wonderful visual correction device. Enjoy. Let this be our new anthem.
Eef van der Worp


Oh, precious lens that graces my eye,
A marvel of modern technology,
You bring me vision where none was nigh,
A gift that fills my heart with glee.
 
A small, but mighty piece of art,
Made to fit my unique eye shape,
A lens that heals my visual heart,
And banishes blurriness without escape.
[seven more verses follow]
Piggybacking in Scleral Lens Wear
Reverse Piggyback With Sclerals
Piggybacking corneoscleral or scleral lenses over an underlying soft lens has been reported by clinicians to reduce fluid reservoir debris, aid initial scleral lens application in neophyte wearers and increase wearing time - as the paper below indicates. But a new clinical approach that surfaced recently to address poor front-surface wettability in scleral lens wear is the use of a “reverse piggyback” system. This means a soft contact lens is applied to the anterior surface of a scleral lens. The aim of this study by a group from Queensland University of Technology in Brisbane (Australia) was to compare the magnitude of corneal edema that this could potentialy induce to that produced by standard scleral lens wear. After correcting for small variations in the initial central fluid reservoir thickness, the central corneal edema was similar between the reverse piggyback (2.32±1.15%) and the standard scleral lens conditions (2.02±0.76%) in 10 young healthy participants with normal corneas. The scleral lens material had a Dk of 100×10−11 units, and the soft lens was a standard delefilcon A (Alcon) lens with a Dk of 140×10−11 units. The authors concluded that following 90 minutes of lens wear, the highly oxygen-permeable reverse piggyback system did not induce a clinically or statistically greater magnitude of central corneal edema compared to standard scleral lens wear in young adults with healthy corneas, and this approach may potentially be suitable to address poor front-surface scleral lens wettability or to correct residual refractive error during diagnostic scleral lens fitting. See also Melissa Barnetts coverage of this topic in Scleral Lens Monthly (May 2023).
Double Piggyback With Sclerals
An amazing picture—again—from Jillian Campbell, an orthokeratology & myopia management specialist who has a large scleral and specialty contact lens practice in Melbourne (Australia). This OCT image shows a patient who has truly outdone him/herself in the contact lens mishap department. This individual somehow managed to apply not one, but two soft contact lenses under their mini-scleral lens, which seems quite impressive. The practitioner removed the extra lenses without incident; while giving the patient credit for their creativity and resourcefulness, she had to make it clear that as a practice philosophy, the patient should plan to stick to the one-lens-per-eye rule for now on.
Keratoconus
Estimating Keratoconus Progression
Marta Jiménez-García is an optometrist from Valencia (Spain) who recently obtained a PhD from Antwerp University (Belgium). The full title of her thesis is ‘estimating keratoconus progression using biometric and biomechanical parameters to adjust treatment protocols for corneal crosslinking (CXL). The introduction (chapter 1) is a book in itself on keratoconus (52 pages, including 372 references). Large variations in progression speed and patterns have been documented, raising questions about the appropriateness of a unique and overly simplified definition of progression. Customised approaches, based on an objective progression risk assessment, are likely to optimise the clinical outcomes and provide some insight into the unanswered question: who, when and how to crosslink? A retrospective longitudinal analysis of more than 700 untreated keratoconus patients is presented in the thesis. Some myths and misconceptions are demystified. It is clear that it is not possible for one definition or parameter of progression to suit all cases. Some variables (provided by a corneal tomographer) outperform others when defining progression. Those with an outstanding performance were used to forecast the progressive trend of the disease, which may be an asset to decide on a closer follow-up. Moreover, alternative definitions of progression based on those variables, as well as the definitions used in CXL clinical trials and the ones currently in use, are explored and put into perspective. The results demonstrate that defining progression requires a stratified approach—combining different techniques, including topography, tomography and densitometry—and the future is one toward data-driven decision-making. A good and promising message. Tastes like Belgian chocolate.
Unreliable Corneal Tomography in
Advanced Keratoconus
An article in Review of Cornea & Contact Lenses states that 'the thinner the cornea, the worse the repeatability of the scans'. These findings may impact clinicians’ assessment of CXL candidacy, the authors mention, quoting a paper from Wadhwa et al in Eye (Lond). The repeatability of corneal tomography measurements was significantly reduced in sub-400 keratoconic corneas when compared to 450-plus corneas in this study. Repeatability limits should be carefully considered, according to the authors, when surgical interventions are planned for such patients. The papers suggests that when assessing patients with advanced thinning (thinnest corneal thickness ≤400µm), clinicians should strive to obtain scans with “OK” quality value if possible and, if unable after several attempts, assess the variability between scans to discern the most likely values of parameters. Using the mean of several measurements—ideally after acquiring a minimum of three scans—may also be helpful. Practitioners are further urged to use newer progression analysis systems that incorporate more repeatable parameters.
Keratoconus Webinar
The National Keratoconus Foundation held a webinar on "Risk Factors for Keratoconus" on May 9, 2023. A video recording is available on the NKCF website. Chantelle Mundy, clinical associate professor in the department of ophthalmology at The Ohio State University, seeks answers to questions such as: 'who gets keratoconus' and 'why?' Risk factors for keratoconus are described, including environmental triggers such as allergies and eye rubbing. The ethnic and genetic factors that put certain groups at a higher risk for the disease are adressed too, as well as why certain family members are affected while other are not.
GPLI
Become a Member
The GPLI Eye Care Professional Membership is a new program that gives eye care practitioners access to premier resources to help advance their specialty contact lens practice at a low annual fee. The membership supports the ongoing efforts of the GP Lens Institute, and member benefits include free printed materials (US only), coding and billing module, staff module, building your practice with rigid lens multifocals, archived webinars, free quarterly COPE-approved webinars, bi-monthly member newsletter, access to recent cornea and contact lens residents symposium presentations, quarterly GPLI podcast (“GPLI Radio”), member directory and more.
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. Disclosure: I-site's editor Eef van der Worp, optometrist PhD FAAO FBCLA FIACLE FSLS, receives educational grants from a number of industry partners but is not related to any specific company.