Introducing the envista IOL Dr Kerrie Meades PersonalEYES Pty Ltd
envista IOL Basic Features Hydrophobic acrylic IOL, single piece 6.0mm aspheric neutral optic, modified C haptic 12.5mm overall length 0 to 34.0 diopters (0 10D, 30 34D in 1.0D; 10 30 in 0.5D) Fenestrated haptics design to evenly transmit forces 360 o posterior square edge UV block
envista IOL Basic Features 2.2 mm wound assisted 6.0 mm
Hydrophobic vs Hydrophilic
Hydrophobic IOLs Advantages Higher refractive index Excellent optical clarity Excellent biocompatibility Better PCO prevention Excellent for surface engineering (toric, diffractive etc) Disadvantages Must be purpose made High tech molecules More expensive
Hydrophobic vs Hydrophilic Acrylic Hydrophilic more flexible lower reflective index PCO rate? higher glistening? Hydrophobic more rigid higher reflective index PCO rate? lower glistening more likely
envista Polymer Novel HEMA styrene copolymer, cross linked polymer, UV blocker 4% water content Refractive index of 1.54 (AcrySof: 1.55, Tecnis: 1.47, Rayner HEMA: 1.46) Glass transition temperature of 30 C
Features of the envista IOL High refractive index thin optic Hard surface difficult to scratch Controlled unfolding 360 square edge favourable for prevention of PCO No glistenings
Nanoindentation Measurement of surface hardness
Nanoindentation Measurement of surface hardness 1 12 10 8 MPa 6 4 2 0 Acrysof envista Sensar Hoya 1 Mentak K et al, ESCRS 2007
envista IOL Very hard, scratch resistant surface High tensile strength
envista IOL
What is glistening? Small fluid filled pockets ( vacuoles / cavitations ) form within the superficial layer of the acrylic IOL Fluid, in the form of vapour, condenses then lines the wall of vacuoles Observed in all types of IOL, primarily in hydrophobic acrylic lenses First clinicopathologic study reported by Nichamin/Apple in ASCRS 1994.
Grade 3+ glistenings Images courtesy of Dr D Chan, Singapore
Case 1 = 20/30 but miserable and explanted Images courtesy of Dr D Chan, Singapore
case 2 case 3 case 4 case 5 case 6 20/20 but miserable Courtesy of Prof D Apple, AAO 2008
Is glistening common? Published studies on glistening formation rates of a very common hydrophobic acrylic one piece IOL Study 1: Nearly 60% between 4 and 22 months postoperatively 1 Study 2: 29.5% (38 cases from 129 eyes) 2 Study 3: 60.4% (157 cases from 260 eyes) 3 FDA Web site, search for intraocular lens glistenings Up to June 2009 : 106 records To date : 223 records 1. Trattler. Identifying the best acrylic IOL materials and assessing the visual significance of glistenings http://www.eyeworld.org/ewsupplementarticle.php?id=261. 2. Moreno Montanes et al. J Cataract Refract Surg. 2003. 3. Colin et al. J Cataract Refract Surg. 2009.
Grading of Glistening Grade Scattering area (% of 2x2mm2) Number Typical sizes Description 1 < 0.5% 0 50 20μ Mild 2 < 2% 51 250 20μ Moderate 3 <10% 251 2500 20μ High 4 > 10% > 2500 10μ Severe
Images courtesy of Dr R Olson
What causes glistening? Manufacturing causes Non uniformity of material 1 Material composition 2 Manufacturing technique 2 Sterilization1 Temperature change Packaging 2 Pre implantation causes Warming 1 Handling 1 1 Shiba et al. Eur J Ophthalmol. 2003. 2 Dhaliwal et al. J Cataract Refract Surg. 1996. 3 Colin. J Cataract Refract Surg. 2009. 4 Wester. J Cataract Refract Surg. 2010.
What causes glistening? Post implantation causes Temperature changes Water vacuoles due to hydrates of IOL 2 IOL power 3 Glaucoma 3 Other conditions leading to breakdown of postoperative visual function and/or the blood aqueous barrier 4 1 Shiba et al. Eur J Ophthalmol. 2003. 2 Dhaliwal et al. J Cataract Refract Surg. 1996. 3 Colin. J Cataract Refract Surg. 2009. 4 Wester. J Cataract Refract Surg. 2010.
Pre hydration How to avoid glistening Traditional hydrophobic IOL : 0.3% 0.5% H 2 O evvista IOL : 4% H 2 O (at equilibrium with NaCL) Packaging 0.9% NaCl solution at equilibrium, no water movement in and out of IOL In aqueous humor: 0.9% salinity again, no water movement in and out of IOL
envista US Pivotal Study 1 IOL glistenings were evaluated via the traditional method of retroillumination slit lamp examination utilizing a photographic grading scale provided in the protocol. The grading scale consisted of (in order of severity), none, grade 0 (trace), grade 1, 2, 3, or 4 No glistenings were reported at any time point Visit 3 (4 Months) Grading Scale N % N % Trace 0 0.0 0 0.0 Mild 0 0.0 0 0.0 Moderate 0 0.0 0 0.0 Severe 0 0.0 0 0.0 Very severe 0 0.0 0 0.0 None 122 100 118 100 Total graded 122 118 Visit 4 (6 Months) 1 Data on file, Bausch and Lomb. Final Clinical Study Report: A prospective multicenter clinical study to evaluate the safety and effectiveness of a Bausch + Lomb one piece hydrophobic acrylic intraocular lens in subjects undergoing cataract extraction.
Posterior Capsular Opacification Designed to Minimise PCO Modified C haptics posterior vault, tight opticcapsule contact 360 o square posterior edge inhibits LEC migration
Hydrophobic, capsule friendly The mean EPCO score at Form 4 (6 months) was 0.032 (SD = 0.101) 1 EPCO Capsulorhexis Score a Form 4 (Days 120-180) Mean (SD) 0.032 (0.101) Min, Max (0.000, 0.726) 95% CI (0.013, 0.050) Distribution of Scores (n, [%]) Within 0.5 116 (98.3) Within 1.0 118 (100.0) N b 118 N missing c 3 Total d 121 1 Data on file, Bausch and Lomb. Final Clinical Study Report: A prospective multicenter clinical study to evaluate the safety and effectiveness of a Bausch + Lomb one piece hydrophobic acrylic intraocular lens in subjects undergoing cataract extraction.
envista IOL Summary Hydrophobic acrylic IOL presents in saline Glistenings: no reports at any time Aspheric UV block optics, 2.2mm incision Safety and effectiveness: superior to FDA grid of historical controls
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