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RGP’s from small to large Regular corneas: Spherical and aspheric lenses Irregular corneas: Small, medium and large lenses Individual custom designs & RGP care and maintenance RGP’s – from small to large Kate Johnson, Brisbane, Australia [email protected] Terminology by size Fitting terminology BOZR / TD / BOZD / PCR1 x PCW1 / BVP PCR2 x PCW2 PCR3 x PCW3 OR BOZR / TD / DESIGN / BVP Fit by changing: CENTRE – back optic zone radius (base curve) – back optic zone diameter PERIPHERY – peripheral curves / eccentricity / sagittal height – total diameter Regular corneas – spherical lens ﬁtting Regular or irregular corneas – aspheric / eccentricity / sagittal lens ﬁtting 7.8 / 9.5 / 7.5 / +0.5 8.3 xx 80.3 .4 / -‐6.00 +1.0 8.8 xx 80.9 .3 +2.0 9.8 xx 90.5 .3 © copyright Kate Giﬀord 2014 1 Eccentricity – 0.5e is average Aspheric / eccentricity / sagittal ﬁtting Sag Regular corneas – spherical lenses 7.8 / 9.5 / 7.5 / 8.3 x 8.3 / -‐6.00 8.8 x 8.9 9.8 x 9.5 Central alignment but periphery is loose Try the 7.5 lens – periphery ideal. Over-‐refraction +4.25 (+4.50) 7.8/9.5/7.5/ 8.0x8.3 / 8.5x8.9 / 9.5x9.5 / -‐1.50 Decrease eccentricity Decrease sag Increase eccentricity Regular corneas – aspheric lenses Modcon (Capricornia) comfort and vision. Upper lid attachment ﬁt ideal. +0.5 x 0.4 +1.0 x 0.3 +2.0 x 0.3 Ê  Can also change back optic zone diameter = steeper = ﬂatter Increase sag Flatten centre Ê  Total diameter 1.50mm less than HVID – larger is better for Ê  Tighten or loosen ﬁt using back optic zone radius (base curve) Ê  Smaller Steepen centre Looser periphery Ê  Tangential peripheral design Modcon (Capricornia) Ê  Larger Tighten periphery Amount of Corneal toricity Initial BOZR (assumes 10.00mm TD)
0.0 to 0.15mm on ﬂat K 0.15 to 0.30mm ﬂat K-‐0.05mm 0.30 to 0.50mm ﬂat K-‐0.10mm >0.50mm toric design indicated Regular corneas – average or not Ê  Trial lens ﬁtting of standard lens àaverage shaped cornea Ê  If these don’t work à non-‐average cornea = tighter = looser Corneal warping Ê  Calculate lens power from trial lens ﬁtting and over-‐
refraction, taking into account vertex distance changes Ê  Look for minimal apical clearance pattern, even alignment pool and 0.4mm wide band of edge clearance Pterygium Pterygium Ê  Centration should be central or slightly high. © copyright Kate Giﬀord 2014 2 The non-‐average cornea Capricornia GBA lens General Bi-‐Aspheric Irregular corneas – small to large lenses KBA 9.0-‐10.2mm R 7.8 / 9.8 / GBA 0.3 / -‐3.25 Epicon 13.5mm KATT 16.5mm L 7.6 / 9.8 / GBA 0.3 / -‐1.00 à R diameter changed to 9.3 Irregular corneas – small to large lenses Bitoric and Post-‐graft RGP’s Keratoconus Irregular corneas – small to large lenses KBA 9.0-‐10.2mm Tricky cyls Capricornia KBA and Advanced KBA KBA – Keratoconic Bi-‐Aspheric central aspheric zone to 0.5mm from edge standard edge lift 0.5mm wide x 9.75mm 10.2 diameter and 0.98 back surface eccentricity standard front surface compensating asphere – sphere on eye KBA ﬁtting Ê  d Advanced KBA allows for two zones of diﬀering e-‐values – BOZD and peripheral curve. can alter BOZR, BOZD and e, PCR and e. © copyright Kate Giﬀord 2014 3 Capricornia KBA & A-‐KBA lenses DD was wearing standard lenses ﬁtting ﬂat. R lens on eye R
-‐13.00 / -‐4.50 x 176 6/15 7.35 / 9.2 / -‐9.50 TLT 6/12-‐2 © copyright Kate Giﬀord 2014 L -‐10.50 / -‐2.00 x 4 6/9 -‐2
7.45 / 9.2 / -‐8.25 TLT 6/9-‐1 R KBA 6.50 / 9.2 / 0.95e L A-‐KBA 6.40 / 9.2 / 6.0 0.90e / 6.8 1.15e 4 Irregular corneas – small to large lenses Case one Epicon 13.5mm 24 year old male. Never worn glasses. Apex of cone R&L 62.0D R -‐1.75 / -‐5.00 x 30 6/24 L -‐1.25 / -‐8.00 x 157 6/60 Case two Case three 19 yr old female. 40 year old female. R keratoconus; L post graft. Rx: R -‐1.75 6/12 L +5.00 / -‐7.75 x 105 6/9-‐ Rx: R +7.00 / -‐3.75 x 145 6/12+1 L +6.25 / -‐3.50 x 30 6/9-‐2 Corneal cyl: R 3.9D @ 60 L 4.6D @ 112 Hypoxia problems with conventional SCL’s; corneal warpage with previous bitoric RGP’s. What do they have in common? Capricornia Epicon lens Large diameter (13.5mm trial) RGP lenses with ‘mini-‐scleral’ eﬀect. Fit central cornea (8.0mm optic zone); then Fit periphery independently – A, B, C, D, E (each 150 um looser) Can also get the lens ‘tucked’ inferiorly under the keratoconic cone, to avoid interaction with lower lid. © copyright Kate Giﬀord 2014 Case one 24 year old male. Never worn glasses. Apex of cone R&L 62.0D R -‐1.75 / -‐5.00 x 30 6/24 L -‐1.25 / -‐8.00 x 157 6/60 Fit with EpiCon R 6.7 / 13.5 / F with E tuck / -‐5.50 6/7.5 L 6.6 / 13.5 / F with E tuck / -‐7.00 6/7.5 5 Case two Case three 19 yr old female. Rx: R +7.00 / -‐3.75 x 145 6/12+1 L +6.25 / -‐3.50 x 30 6/9-‐2 Corneal cyl: R 3.9D @ 60 L 4.6D @ 112 Fit with EpiCon R 7.4 / 13.0 / F / +4.75
L 7.5 / 13.0 / F / +3.50
BCVA with RGP’s Over Ret: R -‐0.75 x 145 L -‐1.25 x 30
6/12+ 6/9+ 40 year old female. R post graft; L KC. Rx: R -‐1.75 6/12 L +5.00 / -‐7.75 x 105 6/9-‐ Fit with Epicon R 7.70 / 13.5 / C with Z tuck / +1.50
L 6.85 / 13.5 / D with B tuck / -‐3.00
6/6 6/6 6/9 6/9+ Irregular corneas – small to large lenses KATT lens – vaults over the cornea KATT 16.5mm KATT lens design Anterior chamber depth (sagittal height) Ê  Spherical or aspheric optic zone (10mm) Ê  Tangent curve parallel to ocular surface (14mm) Ê  Second tangent curve for sag variation (15mm) Ê  Peripheral curve that meets the sclera (15.0-‐16.5mm) © copyright Kate Giﬀord 2014 6 Smith technique – estimating ACD Smith technique – estimating ACD *Slit beam horizontal *Set illumination arm at 60 degrees temporal *Start with small slit and increase size until the anterior lens image and reﬂected corneal image meet in the centre of the lens. Smith technique vs Orbscan Conversion factor: 1.22 x slit length = ACD in mm KATT lens – sagittal ﬁtting Ê  Fitting based on matching the sag of the eye at a chord of 15mm, with allowance for apical clearance Ê  Apical clearance 200-‐300 microns Ê  Limbal clearance 80-‐200 microns Ê  Select trial lens with next highest sag Ê  Trial set 6.0mm (sag 5.715mm) to 8.0mm (sag 3.9844mm) Ê  Observe centre and periphery of lens – allow 30 min settling time KATT lens – assessment KATT lens – assessment Ê  Known centre thickness of 300 microns – slit lamp & OCT © copyright Kate Giﬀord 2014 7 Handling Ê  Insert lens in downgaze Ê  On ﬁtting – ﬁll with saline and ﬂuorescein Miniscleral RGP lenses Ê  Excellent comfort Ê  No lens edge awareness Ê  Use suction cap or 2-‐3 ﬁngers Ê  Excellent vision & stability Ê  Must be inserted bubble free Ê  No dust behind lenses Ê  Remove with suction cap after Ê  Harder to lose pushing bubble up under lens with bottom lid Ê  Handling is diﬃcult to start with Ê  Must be inserted with saline, no bubbles, no debris Ê  Stagnant tear ﬁlm can cause fogging (ocular allergy) Conjunctival blanching Managing ﬁt Change tangents by 1 degree = 30 microns of clearance R 6.0 / 16.5 / 50 / 45 / -‐12.50 T1 (scleral) 50 à 54 = 120um less clearance (ﬂatter) in blanching zone T2 (limbal) 45 à 41 = 120 um more central and limbal clearance R 6.0 / 16.5 / 54 / 41 / -‐12.50 Loosen lens edge at 15.0-‐16.5mm zone KATT lens – long term wear Ê  Vision, comfort, wearing time good and eye is white: © copyright Kate Giﬀord 2014 (maintaining central clearance) Individual designs for irregular corneas Radial keratotomy in 1996 for R -‐5.50 L -‐2.50 R +2.00 / -‐3.75 x 23
6/9 “ghosting” L +1.00 / -‐0.50 x 15
6/6+ 8 RGP post radial keratotomy Boston XO Blue R 8.7 / 5.5 / 10.5 / 7.2 x 0.5 / 8.8 x 1.0 / 10.0 x 1.0 R RGP acuity 6/6+ -‐ “no ghosting” Individual custom designs Ê  Peripheral regularity / irregularity determines lens landing and therefore lens size Highly irregular corneas Ê  Diﬃcult to predict a successful ﬁt – Decentration / limbal coverage / excessive edge lift RGP care and maintenance Hydrogen Peroxide – preservative free Multipurpose RGP solutions – one step Ê  Boston Simplus
Ê  AMO Total Care Two step RGP systems Ê  Boston Advance Cleaner and Conditioning Solution RGP care – Menicon Progent Protein remover, disinfectant and intensive cleaner compatible with all RGP contact lenses. Can be dispensed to patient or done as in-‐oﬃce treatment. Image credits and useful websites Ê  www.sclerallens.org Ê  www.netherlens.com Ê  www.reviewofcontactlenses.com Ê  www.gpli.org Ê  www.contactlenses.org Ê  www.keratoconusinfo.wordpress.com (patient info/blog) Ê  Additional image credits: Richard Vojlay, Melbourne, Australia. © copyright Kate Giﬀord 2014 9 RGP’s – from small to large Kate Johnson, Brisbane, Australia [email protected] © copyright Kate Giﬀord 2014 10

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