An exceptional prescription for out-of-the ordinary needs: RE: -106.00 (+6.00) 0°; LE: -108.00 (+6.00) 25°. Collaboration between Franco-Slovak experts enabled the need evaluation, design, manufacture and fitting of -108 diopter lenses to correct what is probably the world’s highest degree of myopia. This record, set in February 2016, topped the previous achievement of -104 diopters set by the same team in January 2015. The story goes back nearly two years ago, when a veritable chain of vision expertise was set up between professionals in Slovakia and France with the aim of pooling skills to push back the boundaries of what is possible in optometry and optics. The team has already proved their skill twice, and their work is intimately linked to the unique case of Jan Miskovic, a 59-year-old Slovak who has suffered since childhood with severe myopia, amblyopia in two eyes, astigmatism, strabismus and keratoconus. This combination of conditions made treatment highly complex, particularly since his myopia is still progressing, with an average loss in recent years of 4 to 5 diopters per year.
Optometric skills at challenge of technical limits
Via a chance meeting 30 years ago, Jan Miskovic consulted the ophthalmologist who was destined to support him professionally throughout his life. In fact, over the years that his ophthalmic disorders have been progressing, Miskovic has never given up hope and has regularly tested different treatments and optical solutions and consulted numerous experts, even abroad. But he remains loyal to his ophthalmologist and optometrists in Slovakia, who provide the only solution that is effectively working for him: the prescription of ophthalmic lenses as close as possible to his correction requirements.
“We are beyond standards in optics and optometry; therefore we inevitably choose non-standard means...”
However, these requirements are not easy to evaluate. His correction went from -45 diopters in 2001 to -53 diopters in 2008 and -80 diopters in 2012, which at the time required the bonding of two lenses together, one on top of the other, via polymerization. At the time, the limits of technology seemed to have been reached, but the patient’s vision nevertheless continued to deteriorate creating new challenges for the eye care professionals. “We are beyond standards in optics and optometry; therefore we inevitably choose non-standard means of measurement,” explains Sebastian Chrien, optometrist in Banská Bystrica in Slovakia, who is currently taking care of Jan Miskovic. “There are no instruments capable of measuring his myopia level, so we place trial lenses in front of his glasses and ask for his subjective reaction to estimate the required correction as closely as possible. Nevertheless, we are guided by a single golden rule; the subjective improvement of any aspect of his sight,” pursues Mr Chrien. They met each other thanks to photography 5 years ago. Mr Chrien is convinced that photography and optometry combined both together, can help in greater understanding of visual needs and explain the ability of functional seeing despite such a considerable visual impairment: “As a professional photographer (read article), Jan Miskovic is perfectly able to perceive little nuances and changes. This definitively helps in subjective optometric evaluation. He is knowledgeable about image and its different forms. He understands the mechanism of optical aperture, which may help him in enhancing depth of field. When he works, he can find a compromise between visual aspects such as sharpness, contrast, luminosity, and movement. His photographic perception of the world enables him to analyse elements such as perspective, while differentiating subjects with unequal size and clarity and thus estimating distances. Usually, we do not perceive all of that; we unconsciously take all elements for granted, so we do not even notice them. Jan’s vision is different. It is as if he was trained to watch with his mind,” Mr Chrien concludes.
The Essilor network in action
In 2014, Jan Miskovic participated in an event organized by Essilor Slovakia for World Sight Day and the new optical solution presented itself almost by chance. He questioned Essilor’s team there, about the possibility of making special lenses for high prescriptions, and his outlook immediately brightened. “Of course, we had never before received a request like this. But at the time we were starting to develop our special lenses offer so we made preliminary contact with Essilor’s SL Lab (Special Lenses Laboratory) in France, which draws on Essilor’s latest technological advances to provide solutions for patients suffering from severe ametropia (refractive error),” explains Monika Remiasova, marketing specialist of the Group’s Slovak subsidiary. Remiasova contacted Benoit Herpeux, her dedicated customer service representative at SL Lab, who in turn forwarded the request to Alain Massée, head of special lens projects at SL Lab. This new demand represented no small challenge for this first collaboration: -104 D sphere, 6.00 D cylinder (and -103 D for the right eye)! Even so, the response was not long to come back. “I sent an e-mail on 9 October in the morning and received an enthusiastic «yes» the same day. In the meantime, the SL team had to adapt its calculation software to three-digit figure correction (it only went up to -99 diopters), check that it had the right glass raw materials, and begin to think about the design of new surfacing tools,” explains Remiasova.
The SL Lab, an expert in exceptional requirements
In fact, the Slovak request fostered a spirit of competition in the workshop of Essilor’s French laboratory at Les Battants, in Ligny-en-Barrois, which made it possible to set a first record (of -104 diopters) in 2015. The new target in 2016 was clear: meet the various technical and industrial challenges to reach -108 diopters with 6.00 diopters cylinder to prove that the Group can provide customized solutions for all eyeglass wearers, with no exceptions. “The lens design stage was the most complex,” reveals Léonel Pereira, Workshop Manager, Surfacing and Special Lenses, SL LAB. “A lens of this power has to be biconcave. The main constraint concerns the rear surface and its short radius, which supports most of the power in its spherical curve. A toric surface was created on the front side, with a substantial but less pronounced curve.” These specifics spurred the team to opt for a high-index (1.807) mineral material, a biconcave Superdiafal (=antireflective coating) with an asymmetrical facet, which provides optimal optical performance for this correction level. The design calculations were made possible using the Special Lens Calculator (SLC), specifically developed to meet the requirements of special lenses. The inner surface (eye side) of the lens was designed with a power of -77 diopters and an optical aperture 18 mm in diameter, combined with a base curve of +2.50 diopters, unpolished to absorb unwanted reflection. The remainder of the correction was produced on the external surface by a -31 diopter curve (to obtain the total power of -108 D) with a cylinder correction of 6.00 diopters, associated again here with a base curve of +6.00 diopters and an inverted torus to create a perfectly round optical aperture of 24 mm diameter. “This optical aperture gives the wearer a field of view of about +/- 30°, which is satisfactory given the power of the lens. The curvature of the front facet was selected to make a thinner lens possible, but also to facilitate the mounting of the lens at an ideal eye-lens distance,” Pereira concludes.
Creative know-how in lens manufacturing and quality assurance
The manufacturing expertise called upon to produce Miskovic’s lenses can be seen primarily in the creation of the inner surface. A manual ramp-up process was used with a tool specially designed by the SL Lab team to rough out, smooth and polish a radius of about 10 mm, using very precise manual technical moves. This initial optical surface was then measured by reflection with a radiuscope to one-hundredth of a millimeter, and this radius measure was used to calculate the base curve of the outer surface. “This stage is highly sensitive, since achieving a toric surface over a very short distance requires a high level of expertise and perfect technical mastery. The process is adapted for pressure, cycle speed, tooling. Each curve achieved is measured with the radiuscope, which is how we obtain such a high degree of precision.” comments Pereira.
Once the lenses were finalized, they then had to go through quality assurance to verify that power deviation from precision is less than 2%. Since no frontofocometer is capable of measuring such a high level of optical power, a radiuscope was once again used to validate the radii of the base curves of the inner and outer surfaces to enable calculation of the total refractive power of the lens (taking into account the material index) with less than 0.2% margin of error. Verdict: the challenge was successfully met! Moreover, the Slovak subsidiary was able to follow each step in real time and in pictures. “We communicated throughout the process, sending photos to enable our Slovak colleagues to better understand the development of these lenses. It was also a good way to forge closer ties between the teams, which will have more and more opportunities to work together,” Massée concludes.
Optician and Optometrists at work to deliver unique lenses
It only took two weeks to manufacture the lenses and send them to Essilor Slovakia, which entrusted the edging and mounting to its partner, an independent optical store run by two brothers. The store also provides edging and mounting services for the Slovak subsidiary. “Every precaution was taken during the shipping, handling, marking, blocking, edging and mounting of these unique lenses. The last step in particular proceeded without a hitch on Essilor’s Mr Blue digital edger, which proved perfect for this unusual task,” relates Monika Remiasova. The selection of the frame required a great deal of reflection since it had to be able to accommodate these unique lenses with proper centering and an optimum vertex distance.
Living generous and passionate life, while lenses meet satisfaction
The precision work was masterfully accomplished by the optometrists and Essilor Slovakia’s team, according to Mr Miskovic, who was delighted to recover visual acuity of 1/10 in each eye, which for him was highly satisfactory compared to his initial condition (1/20). Despite his residual visual impairment, he keeps on living with outstanding energy and incredible generosity towards others. “His vivacity and his focus on helping others are exceptional. He is looking for children and adults with considerable visual impairments to support them and find a way to help them see better. His diverse activities and social commitments seem to impede him to conform with or to accept that something «by default cannot be done.» By doing sport activities, he discovered that the possibilities are endless and only depend on our will and perseverance,” comments his optometrist, Mr Chrien. He also keeps on living his passions. “It is quite amazing to hear Mr Miskovic talk about the improvement in his day-to-day vision. With these new lenses, which he uses primarily for distance vision during outdoor activities, he can continue to work as a photographer and move about freely for his reporting work (he even climbed Mount Chopok, to an altitude of over 2,000 m!). What better way to illustrate our mission,” enthuses Stanislas Poussin, manager of the Essilor Group’s special lenses business unit.
An achievement that offers new hope
Naturally, the story of how a network of experts mobilized to help Jan Miskovic and his severe myopia does not end here. The progression of his disorder has prompted the various professionals contributing to his care to develop their expertise further and work ever more closely together to meet his needs. After initial feedback from Mr Miskovic in 2015, the SL Lab quickly proposed an improvement to his lenses by reducing unwanted reflections (via the expertise of Essilor’s Irish subsidiary, which specializes in anti-reflective coatings for mineral lenses) and by moving the lenses closer to his eyes.
“Rather than record-breaking achievements, the international team effort around Jan Miskovic is all about human and technological advances…”
In fact, the SL Lab has committed to always finding a solution and developing all the instruments needed to meet Miskovic’s visual need, and those of others who suffer from severe ametropia. Rather than record-breaking achievements, the international team effort around Jan Miskovic is all about human and technological advances that will benefit all those individuals with out-of-the ordinary visual needs.