Corneal physiology & contact lenses-2 Rigid contact lenses III RGP lens care & patient education INSTRUCTOR: AREEJ OKSHAH OTUM 19/11/2009

Care system i.e. care regimen Wetting & soaking Most solutions used for wetting & soaking of RGP lens have many functions in the same solution; enhance the wettability of the lens surface; maintain hydration state (as in the eye); disinfection The most important components in these solutions are the preservatives & wetting agents

……….Wetting & soaking Disinfection: using the lens care system to minimize the micro-organisms (e.g. could cause microbial keratitis & conjunctivitis) that challenge the eye especially in the presence of the lens Factors that enhance the contamination include: with the contact lens by way of patient’s hands; contaminated lens products; lens care packaging; lens case Disinfection of GP lens is accomplished by the presence of lens care product preservatives; lens disinfecting agent Preservatives are active chemical ingredients; either bactericidal (killing microbes) or bacteriostatic (inhibit their growth): preservatives should provide the required degree of infection (different environments); not cause toxicity; compatible with the tear film; compatible with the lens materials to avoid adverse effects. The most commonly used are BAK, chlorhexidine, thimerosal, EDTA (ethylenediamine tetra-acetate), benzyl alcohol, polyaminopropyl biguanide…..

……….Wetting & soaking Wetting agents Wetting/soaking solutions contain polyvinyl alcohol (PVA), or methylcellulose derivatives as wetting agent: PVA: is water soluble; relatively nonviscous; nontoxic to the eye; good wetting on the eye & the lens surface; Methylcellulose: retards the regeneration of corneal epithelium; preferable with more viscous RGP lens solutions

Cleaning Cleaners include: - Nonabrasive surfactants: i.e. detergent cleaning agent to move contaminants (lipid,mucoproteins,debris) from the lens surface; rubbing the or pressure should be applied to remove deposits from RGP lens - Abrasive surfactants: i.e. abrasive particulate matter as adjunctive agent in removing deposits that are difficult to remove by surfactants alone - Surfactant soaking & multipurpose lens care products: traditionally; separate soaking & cleaning solutions (2 bottles); now one-bottle GP lens regimen combining these. These are surfactant soaking and are intended to dissolve deposits during overnight soaking cycle so little pressure is needed - Enzymatic cleaning (liquid or tablets): using weekly enzymatic cleaning regimen for GP lens is important - Special techniques: e.g. cotton tipped applicator with few drops of abrasive surfactants to swab the inside of the lens in addition to the regular regimen & enzymatic cleaning; in case of build-up deposits - in-office polishing & cleaning can be done annually; but renew the lens the other year

Patients own lenses should be stored in hydrated state after removal to maintain hydration & disinfection & wettability & to minimize surface scratch of the GP lens because it’s used often or regularly For office or lab.: store in dry state: Disinfection(5- 10mins soak in H2O2 disinfecting system) then dry the lens,  cleaning & rinsing followed by wetting/soaking prior using dry GP lens

Compliance with lens care regimen Ocular complications associated with non-compliance are more common with soft lens wearers. However non-compliance with the recommended care guidelines for GP lenses causes problems as well.>>>examples for non compliance: Patients doesn’t clean the lens as desired doesn’t adhere to the prescribed wearing schedule doesn’t use disinfection properly doesn’t wash hand before lens handling using inappropriate wetting solution e.g. saliva or tap water (acanthamoeba infection) using expired solutions case is not cleaned or replaced regularly switching to another solution’s brand

Rewetting & lubrication Using a solution for rewetting the GP lens while it still on the eye to rewet the lens surface; to stabilize the tear film; to rinse debris; to break loosely attached deposits e.g. PVA, methylcellulose, preservative-free rewetting drops

Dispensing visit procedures V.A: reductio of V.A compared to the base line  do biomicroscopy to check the lens position & wettability Over-refraction: V.A should be almost equal to the expected V.A…. If not do monocular sphere over- refraction Biomicroscopy: to evaluate lens centration, lag, fluorescein pattern, wettabilty…. Wide beam; low intensity white light; low magnification

Important to patient's education Handling Insertion Removal Cleaning Care regimen Avoid scratch especially when dropping the lens on hard surface Foreign body particles like dust could cause discomfort  should remove the lens Cosmetics (could cause discoloration, damage, surface deposits  should applied after application of the lens) Swimming: not recommended to wear GP lenses; unless wearing goggles

Adaptation Tell the patient that adaptation may take from 10 days to 4 weeks until achieving of no lens awareness…evaluate tearing & discomfort Wearing schedule: Day 1: 4 hours Day 2: 4 hours Day 3: 6 hours Day 4: 6 hours Day 5: 8 hours Day 6: 8 hours Day 7: 10 hours Day 8: 10 hours But all-day RGP lens users should start to wear it 12hours a day Immediately

Visits schedule Daily RGP lens wearers (DW): Visit 1: 1 week after dispensing Visit 2: 1 month after 1 st visit Visit 3: 3 months after visit 2 Visit 4: 6 months after visit 3, then every 6 months Extended RGP lens wearers (EW): Visit 1: 1 week after dispensing (should wear daily wear lens firstly) Visit 2: 24 hours after initiating EW Visit 3: 1 week after initiating EW Visit 4: 2 weeks after visit 3 Visit 5: 1 month after visit 4 Visit 6: 3 months after visit 5, then every 3 months