Dispensingoptics

DO November 2012_1 19/10/2012 09:47 Page 1 dispensingoptics Dispensing Optics PO Box 233, Crowborough TN6 9BD Telephone: 01892 667626 Fax: 01892 667626 Email: [email protected] November 2012 Website: www.abdo.org.uk DO November 2012_1 19/10/2012 09:47 Page 2 DO November 2012_1 19/10/2012 09:47 Page 3 3 dispensingoptics CONTENTS November 2012 3 Cover point Cover point 4 Continuing Education and Training Single vision lenses - now it’s personal by Anthony Blackman 10 Patient and practice management Practice pricing: what you need to know by Antonia Chitty important as we are now fully 13 Frequently asked questions compliant with the 2006 Companies by Kim Devlin Act. 14 Ophthalmic lens The motion to change the name of Tint teaser the Association was defeated, so the by Frank Norville A weekend to remember Association name stays as it is. The The Association’s conference in Board kept to the undertaking made 16 ABDO conference and Stratford-upon-Avon at the end of at the AGM held in Brighton in 2009 to exhibition 2012 Much ado about conference September exceeded all bring forward proposals regarding a by Nicky Collinson expectations. Once again, Elaine change of name and to consult the Grisdale and our conference whole membership. This process is 26 BCLA news organisers, Event Exchange, pulled now concluded. Life in the fast lane out all the stops and put on a weekend that all members can be At the conference gala dinner, ABDO 28 Newsbrief proud of. President Jennifer Brower was able to confer Honorary Fellowship on two of 29 The President’s diary the Association’s most stalwart The AGM was well attended and the by Jennifer Brower results of the two key ballots were supporters - Frank Norville OBE and announced. A substantial majority Malcolm Polley. Both Frank and 36 Optician Index Malcolm have done so much for approved the new Articles of August 2012 summary Association – which is particularly optics through their involvement with the FMO that it was a real pleasure to 38 Contact lens practice have them as guests of the The route to practising as a CLO Association and to recognise their by Rosemary Bailey friendship and support. 35 Diary of Events This is the last year that we will be holding our AGM and conference in the autumn. Next spring we will be holding our AGM at Optrafair in April and our next conference will be in the spring of 2014. n ABDO works in partnership with: Front cover: Boris Becker wears 2013 Wimbledon Sunglass model R9955A from ABDO also activity works in conjunction with: Rodenstock The Worshipful Company of Spectacle Makers DO November 2012_1 19/10/2012 09:47 Page 4 4 dispensingoptics November 2012 Single vision lenses - now it’s personal by Anthony Blackman BSc(Hons) FBDO CL (Hons) SLD SMC(Tech) CertAcc(Open) MSB FRSPH FRI FInstCPD Competencies covered: Optical appliances Target groups: Dispensing opticians, optometrists Progressive power lenses (PPLs) that Monocular pupil distance and patient does not experience incorporate freeform surfacing vertical fitting heights unwanted prismatic effects. However techniques are now commonplace in With the use of appropriate horizontal the oblique power experienced by optical practices. Such lenses often and/or vertical centration the the patient as the eye rotates to view require additional measurements and practitioner aims to ensure that the through off axis points on the lens lifestyle information in order to may vary significantly from the provide a personalised lens for the prescribed back vertex power when patient. However, it is often forgotten Lens Brand Lens Name spherical surfaces are used. Figure 1 that the same technology can be BBGR Asphro PdM shows that as the eye rotates and its applied to single vision lenses. This Essilor SV-360 gaze moves across the lens, the article will look at the range of single Hoya Nulux EP power in oblique gaze vision lenses which are now available Kodak Digital SV (+4.25DS/+1.00DC) is significantly that can be customised. We will look Nikon Seemax SV different from the prescribed back at some of the extra measurements SeeStyle vertex power of +4.00DS. By altering required as well as addressing why DAS the lens geometry of the lens surfaces we take them. Norville Nortor SV we can improve the off-axis Rodenstock Impressions Mono performance of the lens, as both Rupp + Hubrach Ysis Single Vision What is available? spherical and aspherical surfaces can Seiko SPGAZ Table 1 shows a selection of Shamir Smart SV As Worn be used to give different effects 1 personalised single vision lenses which Sola Sola HD SV (Figure 2) . If an aspherical surface is are available in the UK; although not Zeiss Clarlet Individual employed surface power changes as an exhaustive list, it demonstrates that the eye rotates away from the vertex all the major manufacturers now offer of the aspheric surface. Aspherical Table 1: Some examples of free form single vision these lenses. lenses available surfaces are said to incorporate This article has been approved for 1 CET point by the GOC. It is open to all FBDO members, including associate member optometrists. Insert your answers to the six multiple choice questions (MCQs) online at www.abdo.org.uk, or on the answer sheet inserted in this issue and return by 19 December 2012 to ABDO CET, 5 Kingsford Business Centre, Layer Road, Kingsford, Colchester CO2 0HT OR fax to 01206 734156. If you complete online, please ensure that your email address and GOC number are up-to-date. The pass mark is 60 per cent. C-19503 DO November 2012_1 19/10/2012 09:47 Page 5 Continuing Education and Training T&S ST S T a b 40o 40o 40o 30o 30o 30o 20o 20o 20o Effect of lens is +4.00 Effect of lens is 10o 10o 10o +4.25/+1.00 +4.00 plano convex +4.00 plano convex 0o 0o 0o +3.0 +4.0 +5.0 +3.0 +4.0 +5.0 +3.0 +4.0 +5.0 a +4.00D, -6.00D base b +4.00D, -4.50D base c +4.00D, -4.50D base Figure 1: How the back vertex power changes as the eye rotates. (Courtesy of Figure 2: The effect on changing the spherical surface curves on off-axis Professor Mo Jalie) performance. (Courtesy of Professor Mo Jalie) surface astigmatism which is used to points; thus creating a bespoke, neutralise aberrational oblique personalised lens. astigmatism. Aspheric lenses are flatter, lighter and thinner than lenses Let us now look at these three extra with spherical surfaces. Unfortunately measurements which are common to the manufacturer can only produce many of the lenses given in Table 1. what they think is a good lens, Those discussed below are not without knowing how it will be placed universal to all personalised lenses, in front of the eye. The final “as-worn” and some may not require all three effect of the lens may therefore be additional measurements. different to the expected effect. When combined with the frame A Vertex distance and B measurements, the positioning Hopefully we are all used to taking Figure 3: An example of a freeform generator, the Schneider HSC Master of the optical centres will have an this measurement for powers over effect on the thickness of the lenses. +/- 5.00D and that our optometrist We should do our best to ensure that colleagues are recording it on their phoropter used during the refraction. the patient’s PD and the frame box prescriptions (for the trial frame or If the measurements are the same centre distance are similar. Care must phoropter) as both are required to be then all is well; but often there can be also be taken to equalise the edge useful to the dispensing optician. Also a difference which can lead to an thicknesses in the vertical meridian. it is worth remembering that the effectivity error; ie, the effective vertex distance needs to be checked power of the lens will be different to Changing the position of the lens by on collection, as there is no point in that prescribed. If the lens power is altering its vertex distance, taking this measurement during the low and the difference in the vertex pantoscopic angle and faceform dispensing processes if it is not used distances small; then the effective angle all affect the as-worn later. power error will be too small to be performance of a lens. If these noticed by the patient. But with additional measurements are taken The vertex distance is the distance increasing power and larger as part of the dispensing process and from the back surface of the lens to differences in the two vertex passed on to the manufacturer, then the apex of the cornea and should distances; it can sometimes become complex computer algorithms can be measured along the line of sight necessary for the dispensing optician calculate the surface geometry and perpendicular to the spectacle to order a slightly different lens power required so that the back vertex front (Figure 4). to that prescribed. Of course any power is maintained across the lens. such action must be recorded on the Freeform surface generators (Figure 3) The reason for measuring the vertex patient’s records. The effect of can then create a complex lens distance on dispensing is to see if it changing the vertex distance is surface comprising around 40,000 differs from that of the trial frame or summarised in Figure 5. An example Moving a plus lens further from the eye Moving a plus closer to the eye causes causes the lens to effectively be more the lens to effectively be less positive; positive; therefore the ordered power therefore the ordered power needs to needs to be decreased be increased b Moving a minus lens further from the Moving a minus lens closer to the eye eye causes the lens to effectively be causes the lens

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