As a result of the flurry of activity around the wrapped sports lenses available at Optrafair, optician embarked on a project
Many of the lens companies at Optrafair were making a big play of their wrapped lens capabilities, but some practitioners at the show were still voicing scepticism about the ability of prescription houses to successfully glaze wrapped products.
Companies such as BBGR and its sister company Rupp+Hubrach were making bold claims about their ability to glaze pretty much any frame on the market, so optician decided to put them to the test. Our challenge was made to BBGR and its sister company R+H to glaze some of the most tightly-wrapped frames available.
The frames were provided by Rudy Project, supplier of a range of prescription products based around corrective inserts and glazeable frames.
These are used in sports from running, to cycling and golf.
The frames chosen were an Ekynox SX in silver with a mirrored blue lens and an Ekynox in black. Both products as a sunglass are constructed from lightweight performance Grilamid TR55 LX. They both have interchangeable lenses and vents between the frame and the lens to reduce moisture build up. Both have adjustable temples and nosepieces and as a plano product the lenses are optical grade polycarbonate.
The technical team at R+H suggested a soft grey-blue Sports lens with a 50 per cent absorption and a Silver Shade mirror coating for the Ekynox SX. This replaced a blue mirrored Rudy project Laser Blue lens already in place. The suggested lens for the black Ekynox, which had a black tint lens was a Sports Transitions in grey with a Silver Shade mirror coating. Both were glazed with fixed lenses including side vents, as on the original design.
THE GLAZER'S REVIEW
The Rudy Project Ekynox SX was glazed to the prescription of optician editor Chris Bennett (Right -1.5 with 0.75 cyl at 10. Left -2.00 with a 0.25 cyl at 5). The horizontal inclination of the frame was taken using a specially developed measuring aid.
This was sent to R+H with other parameters such as prescription, PD, fitting height, lens size and DBL. With this information R+H designs the sports eyewear to eliminate problems associated with wrap-round/higher base curve glazing: power deviation, optical aberrations such as astigmatism of oblique incidence, prismatic effects at the reference point and decentration due to lens tilt.
R+H has a special Sports product range where the prescription is corrected for aberrations and optimised centring is calculated. If there is a deviation in the calculation of the optimised lenses from the original order data, eg a prismatic effect in excess of 0.75 prism dioptres, R+H will produce the lenses with the corrected data. This was done in the case of the Ekynox SX, and to a lesser extent the Ekynox, where the horizontal inclination was taken from the frame but not when the patient was wearing it. This will lack some accuracy, as frames are stretched when they are placed on the patient's head, thus changing the horizontal angle slightly.
The air vents in the side of the frames presented a challenge which was overcome by the expertise of the master glazers. Even with the high base curves required, the two pairs of lenses were adapted to sportswear giving impact resistant lenses, UV protection, glare protection, prescription corrected to give good all round visual acuity even though the uncut used was over 75mm in diameter.
The Rudy Project Ekynox frames glazed to my prescription are light and instantly comfortable, writes optician production editor Matthew Baldwin, distance runner and mountain biker. My distance vision is clear and free from distortion across the whole visual field (Rx: Right -1.75 with -0.50 cyl at 45. Left -1.75 with -0.25 cyl at 120).
The choice of Transitions with mirror coating works well, giving optimum vision in bright sunlight and shade. The wrapped design offers all-round protection when cycling and prevents mud thrown up from the front wheel finding its way under the lens and into the eye. The air-flow venting design seems to do its job. When running, I find the lenses do not fog up even after I have worked up a good sweat, so long as I keep moving. Once stationary, however, I quickly become misty-eyed.
Frames with this type of glazing are of considerable benefit to the recreational athlete needing vision correction. Contact lenses are the choice for many, but I have found the cleaning regimen and the six-monthly aftercare appointments something of a chore. Perhaps one day I might give daily disposables a try, but until then I'll keep it simple and stick to spectacles.
My first impression was that the glazing job was incredibly neat, writes cyclist and optician editor Chris Bennett. I have had wrapped frames glazed before by reputable companies who have failed to do the job without damaging the frame. On a performance product it is essential to get this right as the reflection created by breaks, cracks and adhesives create reflections that nullify the benefit of the frame.
The lens is snug and even all the way around and the 1mm to 2mm triangular vent in each side is glazed to a tee. The edge thickness is good despite the eyesize but this is hidden behind the thickness of the frame. The graduated tint suits the purpose well and coatings reduce glare front and back.
The all-round vision is excellent and I would have to force my eye as far wide as possible to lose the field of corrective view. Vision is clear, undistorted and corrected all the way around despite the tight curve it is glazed into.