SoftSpecialEdition is a quarterly newsletter that provides independent updates from the international literature on soft specialty lens-related topics.
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The Decade of Soft Specialty Lenses |
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This 'WORLD WIDE VISION' marks the 40th edition of both the column and the newsletter itself. Numerous experts in the field (well, 40 to be exact) have shone their light on soft specialty lenses and their future. It is interesting, when looking back on the nearly 25 years that I’ve been in this profession, that corneal GP lenses were the core of the contact lens industry in the last decade of the 1900s and were the topic of my PhD at the time. The period from 2010-2020 has been coined 'the Decade of Scleral Lenses,' and the decade in between, roughly from 2000 to 2010, seemed to mark the rise of orthokertology, at least from a peer-reviewed point of view as described by Mark Bullimore and Leah Johnson in Contact Lens & Anterior Eye.
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So what's next? This marks the first column by me as editor, as an exception to the rule. Normally, the floor here is for (the real) experts in the field. But if you ask me, I think and envision that the next decade could or should be the decade of soft specialty lenses. Just to name a few considerations: first, we live in a day and age in which everything is customized. The technology to do so is available, and customers demand it. Artificial intelligence is going to help us tremendously in terms of distinguishing the normal from the challenging eye to decide when to 'go custom' and when standard lenses would satisfy. Higher-order aberrations are going to play a much bigger role, and correcting these can only be implemented if we are customizing lenses. Instrumentation to measure the true optical status of the eye is increasingly available and affordable. The two most promising modalities in our industry for soft lens customization are, without question, multifocal lenses and myopia control. But because the eye is such a unique piece of work, it needs a unique (e.g. custom made) lens to provide different optics at different times to be succesful. Soft lenses have just scratched the surface when it comes to their potential in that regard. There is no question in my mind that if we customize soft lenses to the individual needs and optical aberrations of the individual (at a given age), we’ll be able to get much farther. The future will tell us. But that future is, at least partly, in our hands. I'll check back with you in 2030 to see where we are. Wishing you a happy new decade.
Eef van der Worp
Optometrist PhD FAAO FIACLE FBCLA FSLS
Editor of SoftSpecialEdition, Amsterdam, the Netherlands
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Soft Lens 50th Anniversary |
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Glass Splinters, Tap Water & Other Limitations |
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The anniversary of the 40th 'World Wide Vision' coincides with the anniversary of the landmark publication by the true 'masters of visionary,' professor Otto Wichterle (1913–1998) and Dr. Drahoslav Lim (1925–2003), entitled ‘Hydrophilic gels for biological use’ in 1961, now almost 60 years ago. Lim and Dreifus reported the satisfactory tolerance of rabbit eyes to hydrogel lens wear, and in December of that year, Otto Wichterle applied the principle of spin casting to the manufacture of hydrogel lenses to achieve well-formed edges. From about 1963, hydrogel lenses were exported from Czechoslovakia (as the country was called at that time), mostly to Western Europe and Scandinavia. If we go back 50 years to 1971, this most likely will be remembered as the year in which hydrogel contact lenses really hit the market, and therefore, next year may truly be marked as the 50th anniversary of the soft lens as we know it today. It is generally believed, though, that the clinical performance of the original Czechoslovakian hydrogel contact lenses was poor, but historical reviews provide very little explanation regarding their failings, writes Richard Pearson in 'A review of the limitations of the first hydrogel contact lenses' in Clinical & Experimental Optometry. Re-measurement of the Czechoslovakian lenses indicated that the total diameter was similar to that of the cornea, the back optic zone radius was steep and the centre thickness was excessive. Another interesting observation is that these lenses were sealed in glass ampoules, which had to be broken open to access the lenses. An undated Czech leaflet entitled ‘Basic information for oculists’ cautioned that ‘The lens must be washed in running water to remove splinters of the ampoule/if any/and boiled for five to 15 minutes before application. It is recommended to inspect the lens thoroughly to ensure that no glass splinters have cut into it.’
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Light Distortion, Quality of Vision, Task Distance, IOLs |
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Presbyopia remains one of the most promising kids in the class. In an article by Monsálvez-Romín et al, insightful new light is shed on light distortion of soft multifocal (MF) contact lenses with different pupil size and shape. The light distortion index (LDI) in this study was generally higher with MF lenses than with single-vision lenses, varying from 6.1±3.3 % for the MF centre-distance design to 3.7±0.3 % for single-vision lenses. So the MF contact lenses of the study increased light distortion effects (under low light conditions), especially with larger pupils, and the shape of the distortion pattern is also associated with the shape of the pupil. The centre-distance and centre-near designs behaved similarly in terms of light distortion. Sivardeen et al (open access paper) assessed the real-world adoption of presbyopia correction and its impact on quality of vision (QoV). For this, 529 sequential patients (aged 36 years to 85 years) were surveyed on their QoV. Age, sex and driving frequency had no effect of QoV, whereas the distance of the task significantly impacted QoV: it was rated higher by patients whose main tasks were far focused (44%) compared with those who principally conduct intermediate tasks (31%) and was worse still for those whose main tasks were at near (24.7%). From a clinical perspective, it is also interesting to know the effectiveness of MF soft contact lenses for pseudophakic subjects with monofocal intraocular lenses (IOLs). In a study by Tomoko et al in 11 subjects, disposable MF soft lenses were used for 3 months after monofocal IOL implantation. The use of MF soft lenses was effective in these pseudophakic subjects with monofocal IOLs, and favorable binocular vision would be obtained in a range from distance to intermediate.
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Refraction, Aberrations, Biofeedback, Add Power |
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Fedke et al compared the peripheral refraction and spherical aberration profiles along three visual field meridians of 16 commercial single-vision (SV), bifocal (BF) and multifocal (MF) soft contact lenses with a single-vision control. When worn on eye, these lenses produce significant differences in the direction and magnitude of the peripheral refraction and spherical aberration profiles along different visual field meridians. This information may be relevant to refractive development and to myopia control, and it may point to the need for a more custom design approach toward patients. Biofeedback training has been used to access autonomically controlled body functions through visual or acoustic signals to manage conditions such as anxiety and hyperactivity. This study by Wagner et al (open access) used auditory biofeedback to improve accommodative responses to near visual stimuli in patients wearing SV and MF soft contact lenses. Biofeedback training effectively reduced the lag by ≥0.3 D in individuals of both groups with SV and MF wear. The training was more effective in myopes wearing their habitual SV lenses. This study shows that accommodation can be changed with short biofeedback training independent of the refractive state. Walline et al conducted a study to determine whether soft MF lenses slow myopia progression in children and whether high add power (+2.50 D) slows myopia progression more than medium (+1.50 D) add power lenses do. Among 294 randomized children with myopia, treatment with high-add-power MF contact lenses significantly reduced the rate of myopia progression over 3 years compared with medium-add-power MF and single-vision contact lenses.
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Visual Regulation of Eye Growth |
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Ocular Growth and Development |
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For a good understanding of and a solid background in human ocular growth and development, a groundwork review article (open access) by Hughes et al in Clinical and Experimental Optometry is now available. The short abstract here can never do justice to the whole 17-page article, but in essence, it looks at higher-order aberrations and refractive error development in children and in relation to myopia control. Visual regulation of eye growth is key in this. It also shows the difference in higher-order aberration maps between pre-school kids, school-aged kids and adolescents. This again may call for a personal and individual approach toward correction of myopia and its management.
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For more on Myopia Management, including (customised) soft lens topics, see link below for the online Global Myopia Symposium on 25-26 September 2020. Click this link for the full program
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Excellent Vision with Customized Soft Lenses Post-RK/Laser |
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Thibaud Syre is an optometrist, scleral lens specialist and orthokeratology lens practitioner from France. He describes this inspiring case report online of a 58-year-old female who had undergone radial keratotomy some 30 years ago, with laser 'retouching' about 10 years ago. Her refractive state and visual acuity were fluctuating, with maximum achievable acuities of 20/50 (0.4). She did not wish to be fitted with corneal rigid lenses or with sclerals because of a psychological blockage. A pair of custom-made soft post-surgery contact lenses with a unique fully customized design from Switzerland was fitted to this patient. The comfort with these specialty soft lenses was reported to be excellent, and her visual acuity went up to 20/20 (1.0). See topography and slit lamp images below. |
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