26/03/2018. Scratching the Surface Can the surface of a contact lens control ocular comfort?? Contact Lens Surfaces

Transcription

1 Contact Lens Surfaces Scratching the Surface Can the surface of a contact lens control ocular comfort?? James Wolffsohn PhD PgDipAdvClinOptom FAAO FBCLA FIACLE Ophthalmic Research Group Aston University, Birmingham, UK Brennan

2 Current Lens Surfaces Lens Conditioning

3 Lens Conditioning Solutions use can condition contact lenses (e.g. Simmons et al., 2001) A crosslinked into pema not released, but lowered contact angle and decreased protein adsorption (Van Beek et al., 2008) Blister pack carbomethylcellulose can increase comfort and lower staining (Coles et al., 2004) Si blister pack solutions vary mainly in osmolarity (Menzies and Jones, 2011) Lens Material Sustained release from even commercial lenses possible although not linked to comfort (e.g. Costa et al., 2010) Contact Lens Case Cleaning procedures affect storage solution p and osmolality (Abengozar-Vela et al., 2011) owever, lens care can interact with lens material increasing discomfort and staining (Willcox et al., 2000) Molecularly-imprinted contact lenses and nanotechnology has potential to control release better (Ali and Byrne, 2009; Alvarez-Lorenzo et al., 2010) Clear Care [CC] PureMoist [PM] Biotrue [BT] RevitaLens [RL] Saline solution [SS] Comfort Agents What polymers (macromolecules) that modify the surface of the lens. Why mimic some aspects of surface structures of hydrated natural tissue; can improve the sustainability of the hydrodynamic surface layer. assessed in vitro e.g. changes in wettability and friction, but no strong link to comfort summary: ow by adsorption at the surface (e.g. Soflens) by chemical attachment/entanglement at the surface (e.g. Acuvue Moist) or by elimination from the lens matrix. (e.g. Dailies variants) Problems principally persistence especially for surface adsorped systems; simple water-based attachment chemistry for covalent attachment; compatibility with the lens-forming chemistry for matrix modification. Surfactants (surface active agents) hydrophobically asymmetric and adsorb more effectively at surfaces than non-surface active (PMC, PVA, PVP) hydrophilic polymers. Macromolecular surfactants include the Pluronics/Tetronics (= poloxamers/poloxamines) in MPS improve substantivity, but persistence of hydrophilic polymers and surfactants is poor unless (e.g. Acuvue Moist) there is entanglement and chemical (e.g. charge-transfer) interaction. Botanicals and natural polymers e.g. Aloe Vera and hyaluronic acid - wide-spread interest; many products exist, but persistence & concentration issues. Nelfilcon A (Focus DAILIES ) uses soluble polyvinyl alcohol. Polyvinyl alcohol is a hydrophilic polymer that is used in various ophthalmic applications such as artificial tears and comfort drops. Etafilcon A (1-Day Acuvue ) uses polyvinyl pyrrolidone. Polyvinyl pyrrolidone is a hydrophilic polymer which is also used in ophthalmic applications. ilafilcon B (Soflens one day) uses Tetronic Tetronic 1107 is a hydrophilic surface active polymer based on chains of polyethylene oxide (PEO) and polypropylene oxide (PPO) block copolymer. * n * O P o ly v in y l A lc o h o l * n * N O P o ly v in y l P y r r o id o n e Initial Technology Nelfilcon A PVA release Winterton et al., 2007 in vitro demo of polymeric delivery vehicle (nonfunctionalized PVA) controlled by photo crosslinking a macromer species in lieu of monomeric polymerization. Consistent near zero order release over 20hrs Contralateral, masked, n=5 / n=34, comfort increased

4 Tear film stability Pre-Lens Tear film varied between DDs p<0.001 N=34 8, 12, 16 hours after insertion Conclusion Differences between lenses in TF stability not related to comfort Lens Surface and Coating Technology This study utilised a micron thickness coating technology to determine whether surface properties alone would affect ocular comfort, lens surface wettability and ocular physiology of a silicone hydrogel base material. Purpose Methods To determine whether coating technology can enhance the comfort and ocular physiology of a commercial soft contact lens in healthy wearers. Subjects 19 myopes (21.6±1.7 years, 17 female), masked to lens type Measures Evaluations: one week and one month after wearing each CL type, bilaterally in randomised order, each for one month. Subjective comfort (visual analog scale [VAS] & Contact Lens Dry Eye Questionnaire (CLDEQ-8) Objective non-invasive break-up time (NIKBUT) and ocular redness OCULUS Keratograph 5M. vs

5 Ocular redness no difference (P>0.05) 84% p x chose coated CL as final lens preference Method N=20 aged 21.1 ± 3.5 years Double-masked and randomised cross-over (separate full day s (12 hour wear, same time ±1 hours, 1 week apart) trial Senofilcon A base material Uncoated and with 4 different coatings Measures Bulbar and Limbal Redness (Keratograph 5m) NIKBUT; lens surface (Keratograph 5m) Ocular surface staining (fluorescein and lissamine green) Subjective assessment of wear comfort (VAS) On inserion Mid-day End of day No difference between lenses (F=1.627, p=0.219) or ocular surface region (F=0.749, p=0.398), but bulbar > limbal (F=185,357, p<0.001) Redness Grade (Efron scale) Bulbar Nasal Bulbar Temporal Limbal Nasal Limbal Temporal yperaemia No difference between lenses (F=1.511, p=0.208) Lens Surface Wettability Non-invasive Tear Breakup Time (secs) Coating A Coating B Coating C Coating ydropeg S Uncoated Coating A Coating B Coating C Coating ydropeg S Uncoated Coating can reduce resistant to end of day corneal desiccation (F=4.817, p=0.002) Lens Surface Damage No difference between lenses (F=1.885, p=0.165) or with time since insertion (F=0.884, p=0.431). Comfort Ocular Surface Staining (dots) Comfort score On insertion Mid-day End of day 0 0 Coating A Coating B Coating C Coating ydropeg S Uncoated Coating A Coating B Coating C Coating ydropeg D Uncoated

6 Conclusions Clever new technology to enhance lens surface Conditioning Coating Materials Which individuals need these advances can it be predicted in advance? ow can lenses enhance the ocular physiology as the day progresses? ow will you communicate this technology to your patients and adopt them into your practice? Scratching the Surface Can the surface of a contact lens control ocular comfort??