Sometimes I cannot believe how far we have come with scleral lenses, how widespread the modality is today and how many people are benefiting from a modality that less than 10 years ago was still such a niche product fitted by just a few experts worldwide. And the development of the modality was hardly backed up by evidence-based research in the beginning, it all stemmed from good clinical insights. Now it is almost the opposite, at least from a peer-reviewed journal point of view. The BIG lenses are very prominent BIG time in the international literature. Just this fall, one of our leading journals in the field, Optometry & Vision Science, hosted a special edition on sclerals. And another leading journal, Contact Lens & Anterior Eye, will host another (unofficial) scleral lens special in December (but the publications are in press already). In the meantime, the November issue of Eye & Contact Lens also hosts a semi-scleral lens special with the bulk of the publications on that topic. To top it off, for a four card straight: the October issue of Contact Lens Update is completely devoted to sclerals. This newsletter tries to the highlights of all of that, but will have to focus on two main areas - scleral lens optics and intraocular pressure measurement in scleral lens wear - as there is simply not enough space to mention everything that is of interest coming out today. More coverage will be featured in upcoming editions of I-site newsletter. Boy, sclerals are surely growing up. While there are some questions remaining, I am still going to pour myself a BIG glass of wine to celebrate the last decade of scleral lenses and everything that it has achieved. Cheers to this great modality and to its future!

Eef van der Worp

In a highly controlled randomized cross-over trial, Levit et al. compared corneal (R)GP and scleral lens performance in the treatment of corneal ectasia, as quoted from the editorial 'the science of sclerals' by Stephen Vincent for Contact Lens & Anterior Eye (in press). Scleral lenses provided superior comfort to corneal (R)GPs but equivalent optical performance. The editorial further refers to a study by Kumar et al. titled 'Do visual performance and optical quality vary across different contact lens correction modalities in keratoconus?' Using a repeated measures experimental approach, they observed that visual and optical outcomes were similar between corneal (R)GPs and sclerals, with both lens types performing superior to a customized soft lens design. However, in advanced keratoconus with a steepest corneal meridian >53D, scleral lenses provided better visual acuity than corneal (R)GPs did, likely due to improved lens stability and centration. The aim of a study by Assadpour et al. from Iran in Optometry & Vision Science was to compare corneal higher-order aberrations (HOAs) between miniscleral and hybrid lenses in keratoconus patients. The root mean square of the total HOAs significantly decreased after fitting both miniscleral and hybrid lens designs. There was a significant change in the third-order vertical coma and spherical aberration after fitting the miniscleral lens. In the hybrid lens group, a significant change was found only in vertical coma after fitting. But the difference in the post-fitting HOA change between the two groups was not statistically significant.

A study by Sarah Wilting et al. aimed to test whether an equivalent of 12 months of manual cleaning alters the optical and physical properties of conventional and wavefront-guided scleral lenses. Twelve scleral lenses (four identical lenses of three designs) were manufactured in Boston XO material: design A, −5.00D defocus; design B, −5.00D defocus with −0.153-μm vertical coma; and design C, −5.00D defocus with a full custom wavefront-guided correction (second to fifth Zernike radial orders) of an eye with severe keratoconus. One lens of each design group served as a control and was not cleaned. To simulate a year of cleaning, seven individuals cleaned nine lenses (three from each group) twice a day for 27 days using the palm technique and commercially available cleaners, resulting in 378 cleanings of each lens. They found that cleaning over an equivalent 12-month period did not induce clinically significant changes in the optical or base curve properties of conventional or wavefront-guided scleral lenses.

A publication by a research team from Houston (USA) - looked at the the consequence of deliberately placing a wavefront-corrected lens at two pre-defined decentered locations. The study aimed at quantifying the performance reduction accompanying the placement of the wavefront-corrected scleral lens at (1) the average decentration location (ADL) observed across individuals wearing scleral lenses and (2) at the geometric center (GC) of the lens. The HOAs increased as expected, and the predicted visual acuity was poorer at both ADL and GC compared with the aligned condition. Thirty-four of 36 eyes had greater residual higher order aberrations at the GC than at the ADL. In clinical terms, 19 of 36 eyes at the ADL and 35 of 36 eyes at the GC had a predicted loss in VA of three letters or greater. In conclusion: placement of the lens at either ADL or GC is predicted to lead to a noticeable reduction in visual acuity for more than half of the eyes studied.

Wavefront-guided scleral lenses improve vision and decrease higher-order aberrations in ectasia and post-surgical corneas. However, for this to be successful, alignment of wavefront-guided scleral lens corrections to the underlying optics of an eye over the effective pupil is crucial. This case demonstrates the necessity of aligning a wavefront-guided scleral lens optical correction to the eye’s effective pupil, defined by the capsulotomy, with misalignments leading to reduced performance.

As reported in the last edition of I-site newsletter, intraocular pressure (IOP) changes in sclerals keep dominating the debate in the field.

This study looked at the effect of scleral lens Wear on central corneal thickness and intraocular pressure in patients with ocular surface disease. The total average difference in central corneal thickness between before and after scleral lens wear was 7.19μm (544.90±31.29 vs. 552.09±30.30μm), which was a statistically significant increase of about 1%. the increase in central corneal thickness in subjects with ocular surface disease wearing sclerals may be attributed to subclinical hypoxic conditions created by scleral lens wear, the autors state. But they found no significant relationship between scleral lens wear and IOP.

Bruch-membrane opening minimum rim width (BMO-MRW) has been shown to be very sensitive to even minor changes in IOP, with good reproducibility of its measurements. Dan Samaha and Langis Michaud from the University of Montreal (CA) used this the tecnique of BMO-MRW to look at changes during scleral lens wear and found the average diurnal variation for BMO-MRW without lenses to be −4.65 μm after 6 hours, whereas it decreased by 8μm after 6 hours of scleral lens wear. So, scleral lens wear did indeed induce a statistically significant decrease in BMO-MRW that could potentially be attributed to a change in IOP. Although further studies are needed to better understand the significance of the observed changes at the optic nerve head during scleral lens wear, caution seems indicated in patients, and the outlook for a new standard for IOP assessment during scleral lens wear in clinical trials looks promising.

Thomas Arnold and Melissa Barnett host a new podcast that provides 'a nexus for eye care practitioners all over the world,' in their own words. Each month, a specialist from a different country will be featured for a lively discussion of the status of the eye care profession in his or her country. In this first episode, Donald Ezekiel, the Australian pioneer of scleral lenses and a true trailblazer in scleral lens development, is interviewed. The podcast is educational in nature, but with a very personal touch and provides interesting personal details. The latest episode features Annelize van Zyl from Pretoria, South Africa, looking at her innovative practice and involvement with the Boston Keratoprosthesis, and sharing her experience with specialty lenses and low vision patients.

i-site@netherlens.com.