February 2023
Column
Im-Poster
Just back from the Global Specialty Lens Symposium (GSLS), filled with new ideas and energy. This meeting made me realize a couple of things. First and foremost: what a wonderful community we have! The vibe, post-Covid, was completely back! It is hard to not get excited if you have about 1000 souls on the floor (eye care practitioners, educators, researchers, industry) all passionate about specialty lenses. As for the research: we had 155 submissions for posters and free-papers, and of high quality. Something was striking though. As you may expect, sclerals were very popular: 57 posters/papers in that category. This was followed by myopia management and anterior segment disease (28 and 20 posters/papers, respectively). What about contact lens solutions, lens care & safety? One. One poster on the topic. Presbyopia then? Two. Two posters. Rigid corneal lenses did get 14 poster submissions, but almost all were case reports. Just one poster submission was in the research section on that topic (see below). One. At the same time, if you look at the annual contact lens prescribing survey for 2022, 14% of all new fits are with rigid lenses, and of these, 23% are scleral and 20% are ortho-k, so almost half in total. The other half? Corneal lenses. And the absolute numbers looking at lens orders is certainly more skewed toward corneal lenses. Are we dealing with an imposter phenomenon? Let’s focus on more than sclerals in our beautiful specialty lens arena. Hope to see many more posters and paper submissions in other categories next year. And sure hope to see you at the next GSLS in January 2024 to discuss this.
Eef van der Worp
Corneal Topography
Elevating Ocular Surface Shape
The one poster submitted at GSLS with a study on rigid corneal lenses did receive 3rd prize in the research category. The poster (#14) by Kojima et al looked at how elevation data can help make the decision on when to fit a corneal or a scleral lens. A novel corneal topography algorithm was employed to search the elevation map for the meridian of greatest change in height. The calculation was performed across an 8mm chord diameter (to match the optical zone size of standard corneal lenses) in 90 consecutive irregular eyes. The study supports previous findings showing that eyes with more than 350 microns of elevation difference are more challenging to fit using corneal lenses; 100% of patients above this threshold required a scleral lens to achieve a satisfactory result. Approximately 37% of patients with less than 350 microns required scleral lenses, which may indicate that the degree of corneal asymmetry contributes in addition to the magnitude of elevation change across the ocular surface. But 96% of subjects with 0-100 microns of difference and 94% with 101-200 microns of elevation difference were successful with corneal lenses. While those categories seem very straightforward, the group with an elevation difference between 201-400 microns is a little less black-and-white: about 1 in 3 eyes could be fit in corneal lenses, two-thirds were fitted with sclerals. But the study indicates clearly that in general, the lower the elevation change across a single meridian of the corneal surface, the higher the fitting success with rigid corneal lenses, whereas the greater the elevation change, the greater the likelihood that scleral lenses will be required to manage the asymmetry of the eye.
Specialty Contact Lens & Anterior Eye
The February edition of Contact Lens & Anterior Eye is a special issue on specialty lens research, with guest editors Stephen Vincent and Pauline Cho. In line with the trend noted in the column above, the bulk of the topics focus on scleral lenses and (especially) ortho-k. More on optical (zone size) improvements with those in the next issue of I-site newsletter. This edition covers quality-of-life, comfort and physiology issues related to ortho-k and sclerals.
All images in this section courtesy of Antonio Calossi (optometrist, Florence - Italy)
Orthokeratology
A study by Xie et al from China evaluated the changes in ocular surface parameters during ortho-k lens wear and determined their correlations with ocular discomfort symptoms. Fifty individuals were enrolled. Overall ocular surface disease index score and two subscale scores (ocular symptoms and vision-related function) significantly increased at the 3-month visit but decreased to levels close to baseline at the 12-month visit. In general, ortho-k increased ocular discomfort symptoms and decreased the function of the tear film, mainly within the first 3 months of lens wear. Tear-related visual function parameters were correlated with ocular discomfort. A new parameter, the tear film objective scatter index, was more sensitive in detecting the quality and stability of the tear film than were traditional indicators.
Another study from China, by Guo et al, assessed the tear film surface quality after ortho-k using a Medmont corneal topographer. One hundred forty-five children were observed, and the overall tear film disruption and central tear film disruption were measured and were both found to be significantly increased at the 1-day follow-up. This change remained consistent through to the 12-month visit. A sub-group of 11 children were discontinued for 1 month before being refit with ortho-k lenses of a different design. Similarly, there was a significant increase, but this returned to baseline levels after ceasing lens wear. In a sub-group of 23 monocular ortho-k wearers, the measured values increased in the lens-wearing eyes but remained stable in the lateral eyes. Conclusions: objective measurements of tear-film quality are reduced in children after being fitting with ortho-k lenses, but they return to baseline after 1-month of lens cessation. This study also emphasized the importance of ensuring that the tear film surface quality is continuously monitored during ortho-k lens wear.
This study from Malaysia by Mohd-Ali et al compared vision-related quality of life between wearing ortho-k lenses and spectacles in myopic children living in Kuala Lumpur. A total of 70 subjects participated in this study (45 ortho-k and 25 single-vision spectacles), with a mean age of 10.9 ± 0.7 years. The mean values for all the scores in the survey were higher for ortho-k than for glasses. With regard to symptoms during ortho-k lens wear at night, less than 10% reported having difficulty falling asleep, itching/burning/dry eyes or foreign body sensation after lens application. Based on this survey, the authors claim that ortho-k improves the vision-related quality of life of myopic school children and could be considered by more eye care practioners as an option when managing myopic children.
Scleral Lens Wear
A review article by Schornack et al looked into the topic of intraocular pressure (IOP) and scleral lens wear. IOP is maintained through complex and interrelated systems that control aqueous production and drainage, and it has been suggested that scleral lens wear may disrupt these vital homeostatic processes. Some studies have evaluated IOP using standard techniques prior to lens application and following lens removal, or through a large central fenestration. Other studies have utilised instruments that facilitate assessment of IOP on the peripheral cornea or conjunctiva overlying the sclera (e.g., Schiotz, transpalpebral and pneumatonometry). Two studies have recently evaluated changes in optic nerve structure during scleral lens wear. Conflicting results have been reported on this topic, much of which examines changes in IOP in healthy subjects over limited periods of time. Only a few studies have reported on long-term effect, but after lens removal. So, the jury is still out, but ongoing clinical assessment of optic nerve structure and function is advisable in patients at risk for glaucoma who require scleral lenses.
Investigators from Spain looked at potential meibomian gland dropout in scleral lens wearers, as has been observed with other lens modalities. Infrared meibography was obtained of the upper eyelid using the Cobra fundus camera in 43 volunteers and in 29 subjects after 1 year of scleral lens wear. Meibomian gland dropout percentage was not statistically different between the two groups. Nevertheless, the group with the volunteers showed higher grey pixel intensity values compared to the other group. Statistically significant correlations were found between gland visibility metrics and gland dropout percentage. But in conclusion, the authors state that scleral lens wear appears to not adversely affect meibomian gland dropout and visibility while it might improve dry eye symptoms after one year of lens wear, although these preliminary results should be confirmed with future research.
Another paper from the SCOPE group describes international scleral lens prescription and management practices. Data were collected for 259 patients (419 eyes). Most participants (60%) practiced in the US, 75% worked primarily in community practice, and 58% had more than 5 years’ experience fitting scleral lenses. Indications for scleral lens wear were corneal irregularity (87%), ocular surface disease (9%), and uncomplicated refractive error (4%). During the fitting process, the mean (SD) number of lenses ordered was 2.4 (1.6) (range, 1–16) during 3.8 (2.4) visits (range, 1–18). Of patients, 62% used a daily surfactant cleaner, 47% used hydrogen peroxide disinfection, and 67% used single-use vials of nonpreserved saline.[LS1]  Mean lens diameter was 16.2 (1.1) mm (range, 11.8–23.0). The landing zones were spherical (64%), toric (26%), quadrant-specific (7%) and custom (3%) designs. Optical power was spherical in 70%, toric in 27% and higher-order aberration correcting in 3% of lenses, while 5 lenses had multifocal optics.  [LS1]May want to add for the nonpreserved saline that it is used as a filling solution, as the other two mentioned are for cleaning and disinfection.
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.