Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Care and maintenance of contact lenses


Published on

  • Login to see the comments

Care and maintenance of contact lenses

  1. 1. CARE AND MAINTENANCE OF CONTACT LENSES MANOJ ARYAL B. Optometry IOM, Maharajgunj Medical Campus
  2. 2. PRESENTATION LAYOUT • Introduction • Overview of care and maintenance  Care and maintenance of soft contact lenses  Care and maintenance of RGP contact lenses  Lens deposits  Patient education and compliance: use and care of contact lenses  Discussion
  3. 3. Introduction  Most crucial aspect of contact lens wear  Influence the success of contact lens wear and patient’s satisfaction with their lenses
  4. 4. Overview Of Care And Maintenance  Purpose: Clean lens Good comfort Good vision Safe lens wear
  5. 5. Components:  Cleaner Daily cleaner Weekly/protein cleaner  Rinsing solution  Disinfecting solution  Lubricating/Re-wetting solution  Lens storage cases
  6. 6. Cleaners Most common components  Surfactants(surface active agents) Non-ionic Ionic Anionic Cationic Amphoteric  Buffers  Osmolality adjusting agents  Preservatives  Chelating agents  water
  7. 7.  Cationic surfactants are not normally used with SCLs bcz.  They may be bind with lens particles  Preservatives are primarily used to protect the cleaning solutions from microbial contaminations after opening
  8. 8.  Surfactant cleaners:  Normally used in conjunction with finger rubbing  Rubbing step is always followed by rinsing step  Rubbing: dislodges the contaminants  Rinsing: removes the displaced contaminants
  9. 9. Daily Cleaner Function  To remove:  Loosely bound foreign matter  Cell debris  Mucus,lipid, protein  Cosmetics or other surface contamination
  10. 10. Dailey cleaners Contains friction enhancing agents/polymeric beads  These are the small solid particles that behave as a mild abrasive but which do not affect lens surface  Eg. Allergan LC 65&B&L sensitive eye daily cleaners
  11. 11.  Extra strength daily cleaner  Alcon Opti-clean, Polycleans ii  B&L Concentrated cleaner  CIBA Miraflow
  12. 12.  General procedure:  Wash hands  Place lens in palm of hand  Place 2-3 drop of cleaner on each lens  Rub with forefinger for about 15 seconds per side using a to and fro and fro action. Rolling the forefinger in both directions cleans the lens periphery
  13. 13. Weekly cleaners: Usually formulated for protein removal Sometimes called enzymatic cleaners bcz. most contains one or more proteolytic enzymes
  14. 14. Rinsing Solutions Function:  Removal of loosened lens contaminants  Removal of residual cleaners  Rehydrate lens  Resolve enzyme tabs Most common and most economical rinsing solution is saline
  15. 15.  Saline:  Isotonic saline can also be used:  As a medium for enzyme treatment in some regimens  To elute unbound adsorbed or absorbed lens contaminants  To rehydrate lens
  16. 16. Disinfectio nFunctions:  Kill or deactivate potentially pathogenic organisms includes  Bacteria  Fungi  Virus  Amoebas  Maintain lens hydration
  17. 17.  Types  Thermal  Chemical Conventional Polymeric Tablet  Hydrogen peroxide
  18. 18. Thermal Disinfection  High temperature kill micro-organism by:  Denaturation of cell components  Disruption of plasma membranes  DNA damage  2 methods of applying heat to lenses in a lens storage case
  19. 19.  Wet:  immersing the lens case in water at or near its boiling point or  Placing the lens case above boiling water  Dry:  direct heating of lens case by a matching, snug fitting, electrically heated device  After heating cycle allow lens to cool before use
  20. 20. Advantages  Short disinfection cycle times(10-30)  Very effective in destroying microorganisms  Low risk of toxic or allergic reactions Disadvantages  Incompatible with some lenses(usually SCLs)  Suitable electrical power for heat units may not always be available  Can cause lens discoloration  Increased protein deposition
  21. 21. Chemical Disinfection  Conventional Chemicals:  Thimerosal  Chlorhexidine  Sorbic acid  Benzalconium chloride  Iso-propyl alcohol
  22. 22.  Thimerosal:  Effective as anti-fungal agent  Reduced effect when combined with EDTA  Cytotoxic to corneal epithelium  Chlorhexidine gluconate:  Antibacterial agent  Leaches from Group 1 to Group 4
  23. 23.  Benzalkonium chloride  Antibacterial agent  Cytotoxic  Sorbic acid  Anti bacterial with limited antifungal activity  Not cytotoxic  Causes discolouration of lenses
  24. 24.  Alcohol:  Cleaners: isopropyl alcohol and ethanol  Disinfection : isopropyl alcohol  E.g.CIBA Miraflow used in disinfecting solutions  Both disinfectants and cleaners contain large conc. of alcohol  Cleaner 20%  Disinfectant 17%
  25. 25. Chemical Disinfection: Disinfectant Sensitivity Symptoms  Sudden decrease in ocular tolerance  Decreased wearing time(2- 4 hour)  Burning, grittiness, dry sensation Signs  Conjunctival redness  Epithelial damage  Corneal inflammation
  26. 26. diffuse corneal staining resulting from a reaction to a disinfectant or a preservative. A mild red eye (conjunctival hyperaemia) due to sensitivity to a solution component, usually the disinfectant.
  27. 27.  Disinfectant sensitivity depends upon:  Preservative type  Preservative concentration  Lens material  Soaking time Lens age  Patient susceptibility
  28. 28. Polymeric Disinfection  Relatively recent class of disinfection  Most common examples are  PHMB  Polyquaternium-1  Used in multipurpose solution
  29. 29.  E.g B&l Mps ReNu,Alcon Opti-Free, Allergan Complete ,CIBA Solo care soft  Disadvantages  Reduced disinfecting power  Rub/rinse still required  Compliance is more important
  30. 30. Tablet Based System  Chlorine tablet system  Halane(sodium dichloroisocyanurate)  Halazone(poly(dichlorosulphanoyl)benzoi c acid)  E.g Alcon Softab, Sauflon Aerotab  Chlorhexidine  E.g Optim eyes
  31. 31. Hydrogen Peroxide Disinfection  Along with thermal disinfection is one of the earliest SCLs disinfection method  Hydrogen peroxide:  Produces free oxygen radicals which are very reactive and quickly bind to many cell components  Decomposes to water and oxygen  Requires neutralization  Can be formulated preservative free  Can be supplied in one-step form  Must be stabilized
  32. 32. Hydrogen peroxide: neutralization Non selective anti-microbial agent Minimum 3 hr in 3%h2o2 recommended Bacteria 10-15 min Fungi 60 min Acanthomoeba 3-6 hour Neutralization: 2-step peroxide disinfection 1-step peroxide disinfection
  33. 33.  Neutralizers:  Sodium pyruvate: Na2C3H3O3+H2O2=NaC2H3O2+H2O+CO 2  Sodium sulphite: Na2SO3+H2O2=Na2SO4+H2O  Sodium thiosulphate: 2Na2S2O3+H2O2=Na2S4O6+2NaOH  Sodium tetrathionate  Highly deleterious to cornea 2-step peroxide neutralization: stoichiometric(reactive) Neutralization
  34. 34. 2-Step H2O2 Systems: Catalytic Neutralization  Have longer neutralization time  In either tablet or solution form, neutralization and equilibrium time of 10-15 minutes are generally adequate for low water content lenses Higher water SCLs require longer times of up to 1 hour  Neutralizers:  Catalytic disc in second lens case  Catalase solution or tablet
  35. 35. 2- Step Peroxide Disinfection Advantages  Can vary time of disinfection  Concurrent protein removal possible  Suited to occasional wear Disadvantages  Less convenient  Some have preserved neutralization solution  Potential for irritation  expensive
  36. 36. 1-step neutralization system  Formulated so that the peroxide disinfection and neutralization are performed during the recommended time  With tablet using system a delay is applied to the neutralization phase  With disc-based systems, no delay is applied to the neutralization phase  When neutralization is performed as separate step, the system is called atwo-step neutralization
  37. 37.  Disadvantages:  Inflexible neutralization time  H2o2 concentration decreases rapidly(3%-1%in less than 10 min)  Not effective against fungi and acanthamoeba species  Catalytic disc needs regular replacement  Potential for irritation  Possible recontamination
  38. 38.  In systems using catalytic disc, whenever H2O2 is in contact with the disc, the concentration is decreasing  User of disc based 1- step systems should be instructed to place their lenses in lens baskets before pouring peroxide solution into the case  If not, much of the peroxide is neutralized by exposure to the disc before lenses are immersed
  39. 39. H2O2: Effect On Lens Parameters  May cause reversible parameters changes in high water lenses  HWC requires longer soaking time to reverse  Caution:  Discomfort and irritation follow lens insertion if residual peroxide present  No permanent damage to normal ocular tissues  Corneal staining might be observed
  40. 40. Protein Removers  Most protein removers are based on enzymes  Enzymes cleaners work by leaving substrate specific enzymes break down their target molecules, thereby facilitating their removal Protease target proteins Lipase target lipids  While amylase targets polysaccharides
  41. 41.  Enzymes can also remove other types of deposits if they are incorporated in the protein deposits  Enzymes may also break bonds between the lens materials and proteins  Enzymatic cleaning does not replace the disinfection system
  42. 42.  Procedure:  Used regularly, after the daily cleaner and rinsing step  Lenses should be soaked in enzyme dissolved in solution/saline for 15 min to overnight, depending upon manufacturer  Lenses should be thoroughly rubbed and rinsed again afterwards
  43. 43.  Enzymatic protein removers Contain one of the following  Papain  Pancreatin  Subtilisin A &B
  44. 44.  Papain:  protease i.e. enzyme that act as protein specifically  Derived from papaya plant  Usually have a slightly unpleasant odour due to the inclusion of cysteine  Binds to contact lens material and can cause sensitivity reaction  Short 15 min soaking time possible E.g. Allergans Soflens enzymatic cleaner or Profree
  45. 45.  Subtilisin A&B:  Proteases  Subtilisin A formulated specifically for use in hydrogen peroxide lens care systems  Subtilisin B is formulated for use in conventional chemical and thermal systems
  46. 46. Re-wetting/ Lubricating Drops  Used for:  Promote comfort  Reduce deposit induced friction b/w eyelids and corneal surface  Rehydrates the lens  Lubricating and re-wetting eye drops are formulated with viscosity-enhancing agents(commonly polyvinyl alcohol, methylcellulose etc)
  47. 47. Lens Storage And Cases  To avoid contamination, lens cases should be rinsed after every use and the lenses stored in fresh solution  Acanthamoeba and other free living protozoans are especially prevalent among those using tap water for rinsinf their lens cases, using home made saline as a rinsing solution for contact lenses, or swimming with contact lenses.  Biofilm or glycocalyx formation on the surface of contact lens storage cases can horbour pseudomonas aeruginosa and serratia marcesens
  48. 48.  Care of lens cases:  Discard used solutions  Scrub with a toothbrush and detergent weekly.oil free soaps or detergents are recommended  Rinse with hot water and rub thoroughly with a clean, dry tissue
  49. 49. Lens replacement schedule and care regimen  Daily disposable:  Does not require use of surfactant cleaner, disinfecting solution or weekly enzyme  If needed the patient can use in eye re wetting drops or sterile saline for rinsing prior to insertion  Regular disposables  Suitable care includes multi-purpose solutions  No weekly protein removal is needed  Other options:  Surfactant cleaners  1-step hydrogen peroxide disinfection  Lubricating/re-wetting solutions
  50. 50. Care regimen guidelines for frequently replaced lenses,conventional lens wearers
  51. 51. In-office diagnostic(trial set) lenses SCL use heat if possible otherwise peroxide  RGP use peroxide or store lens dry  Re-disinfect non disposable inventory trial lenses at least once a month  In-office procedures  Oxidising agents  Standing waves  Ultrasound  Ultraviolet  Microwave Common oxidizing agents used are LiprofinTM, 6 or 9% peroxide
  52. 52. Care and maintenance  Important steps for patients  Wash hand prior to handling lenses  Rub each side of each lens for 10-15 seconds using a surfactant cleaner  Rinse each lens thoroughly in normal saline  Disinfect contact lenses in fresh disinfecting solution in a clean storage case  Remember  Do not mix solution type and brands  Assess patients compliance  Repeat instructions and assess demonstration to patient  Remind patient to clean lens case weekly
  53. 53. The Message  C lean  R inse  A nd  D isinfect  L enses  E very time
  54. 54. RGP Care And Maintenance  Purpose:  Minimize deposit accumulation  Increase lens wettability  Facilitate comfort and vision during lens wear  Deposits: RGP material containing Siloxane are more prone to protein deposits Fluorine are more susceptible to lipid coating
  55. 55.  Practitioner choose low Dk over high Dk RGP material despite the benefits of higher oxygen permeability  The high Dk RGP lenses are more susceptible to lens surface deposits than their low to moderate Dk counterparts  Cleaner :  daily surfactants  Protein removers  Disinfecting or soaking solution  Wetting solution  lubricants
  56. 56.  Daily surfactant:  Similar to their SCL counterpart  An alcohol based cleaner is well suited to fluorosiloxane lenses which tend to acquire lipid deposits  Patient should be cautioned against soaking RGP lenses in alcohol based cleaner  Further, they should be adjusted to rinse their lenses thoroughly immediately after using such cleaners bcz. they have been shown to alter lens parameters if allowed to remain in contact with the lenses
  57. 57.  Enzyme: recommended for protein removal in deposit prone wearers  Polish: may be necessary for lenses over 12-18 months old  Cleaning pad; may be effective in removing some deposits from RGP lenses  Avoid:  Vigorous rubbing  Excessive pressure on lens  Prolonged cleaning with mildly abrasive cleaners
  58. 58.  Recommended technique:  Place the lens in the palm of hand  Rub lens with finger for minimum of 10 seconds  Rinse with saline or tap water approved for drinking
  59. 59. Disinfectio n Although microorganisms can not readily attach to RGP lens surfaces , they can attach to deposits  RGP lens should not be thermally disinfected As this can cause warpage  Soaking time (4hour to overnight or as recommended)
  60. 60.  Preservatives used includes:  Thimerosal  Phenyl mercuric nitrate  Benzalkonium chloride  Chlorhexidine  Poly(amino propyl bigunide)  And polyquaternium-1 H2O2 IS NOT NORMALLY USED GOR RGP LENSES
  61. 61.  Wetting and soaking:  It is better for RGP lens wearer to wet-store their lenses  If RGP lens are stored dry, parameters such as BOZR will invariably flatten and the lens surfaces may not wet properly  Wet storage also improves initial on eye comfort and greatly assists microbial control of lens storage conditions
  62. 62.  RGP wetting and soaking solution contains:  Antimicrobial agents to disinfect the lenses and to preserve the solution after initial opening  Wetting agent to improve lens wettability  Viscosity-enhancing agent to thicken the formulation  Buffer system to adjust and maintain solution pH  Salts to adjust solution osmolality
  63. 63.  Wetting agents:  Better wetting result in better vision and greater comfort  Improve the wetting characteristics of the lens surface:  Convert hydrophobic surface to hydrophilic  Assist tear film to spread more easily and evenly on lens surface  Increase comfort on insertion  E.g. Poly vinyl alcohol, Polyvinyl pyrolidone, Polysorbate
  64. 64.  RGP lens non-wetting areas due to:  Deposits  Manufacturing process  Polishing compounds  Surface combinations  Rinsing solutions  RGP lens can be inserted directly into the eye after soaking in appropriate wetting/soaking solutions  Burning on insertion: change to a less viscous solutions  Stinging on insertion: change solution
  65. 65.  RGP-MPS  One bottle system(OBS)  Combination of cleaning, disinfecting, and soaking functions  E.g. Allergan Total, Boston Simplicity, CIBA SOLO-care-hard  Lubricating drops:  Used during lens wear to:  Improve comfort  Clean lens surface  Maintain lens wettability
  66. 66. Trial Set Disinfection/Storage  RGP trial lens disinfection: the method recommended is:  Clean with alcohol-based cleaner immediately after use  Place in a clean container  Wet storage in a soaking solution when lens is not being used  Clean the storage solution periodically(monthly)  Clean lens again immediately before next use
  67. 67. Summery  Because of their non-absorbent nature, surface properties, rigidity and durability RGP lenses are easier to care for  Clean ,rinse and disinfect lens every time(CRADLE)  RGP lens kept in use longer than SCLs Therefore efficacious lens care area more important  Consider a programmed replacement scheme
  68. 68. Contact Lens Deposits  Definition: Any lens surface coating or lens matrix formation which is not flushed or rinsed from the lens by the tears during blinking. In effect, anything that remains on the surface despite blinking is a deposit
  69. 69. Deposit formation:  Tear protein(lysozyme) are attached to the lens  Tear evaporates and leave residue on the lens  After protein are deposited, other components of the tear film (such as mucin) may adhere to protein  Over time. Layers build up and structural changes take place(e.g. Denaturation) Factors influencing lens deposition:  Individual difference in tears  Lens materials  Care system  Wearing schedule EW might induce more deposits than DW  Environment  Patient hygiene
  70. 70. Types Of Deposits Teal related  Protein  Lipid  Jelly bumps  Inorganic deposits Non-tear related  Fungi  Lens discoloration  Mercurial deposits  Cigarette residues  Surface combination  Rust spots
  71. 71.  Protein deposits:  Are a semi-opaque or translucent film usually thin whitish and superficial  Have a frosted glass appearance  may cover lens surface partially or full  Cause the lens surface to become hydrophobic  Can crack and peel if thick
  72. 72.  Factors favouring a build up of protein on a contact lens:  short BUT  Ionic binding capacity  Inadequate cleaning especially of the lens periphery  Altered blinking  Heat disinfection  Tear deficiency or altered tear composition  Chronic allergies and GPC
  73. 73. Lipid Deposits  Appears as greasy, smooth, and shiny adherent films on both RGP and soft contact lenses  Best observed between blinks  Appears as a thick ,oily coating  Lipids involved includes: phospholipids, neutral fats, triglyceride, cholesterol, cholesterol esters, and fatty acids  Origin: mainly from meibomian gland
  74. 74.  Predisposing factors:  Tear film quality  Slow blink pattern  Poor lens compliance  Careless use of inappropriate cosmetics/lotions
  75. 75. Jelly Bumps  Appear as a clumps of raised transluscent mulberry like deposits  Typically form in inferior, exposed portion of lens  Occur more frequently in high water, ionic, EW lenses
  76. 76. Predisposing factors  Quality of tear film  Poor blinking  Lens surface contamination  HWC>LWC  Aphakia cleaning consequences  Large and numerous jelly bumps lead to wearer discomfort  Large deposits can cause the lens to attach to the upper lid so that each blink causes excessive lens movement  When located within pupil zone-visual acuity can fluctuating  Maya also cause mechanical irritation of tarsal conjunctiva  In extreme case, may cause CLPC
  77. 77. Inorganic Deposits  Calcium carbonate deposits  Calcium phosphate deposits  Appearance:  White crystalline specks  Can be small or large  Rough surface  Penetrate lens surface if severs
  78. 78. Fungal Deposits  Appearance:  Filamentary growth on and into lens  Usually white, brown or black  Fungal formation  Spores on lens surface from eye or environment  Proliferates to large visible growth  Penetrate lens matrix  Contact lens good medium for fungal gruwth
  79. 79. Lens Discoloration  Can result from:  Natural lens ageing  Surface contamination  Mercurial deposits
  80. 80. Mercurial deposits:  Appear as a greyish to black discoloration  Reuse of thimerosal containing solution is one cause  To prevent avoid mercury based preservatives Ageing  Polymer breakdown  Chemical absorption  Handling  Stress and strain  deposition
  81. 81.  Surface contamination  Make up  Moisturizing lotions  Hairspray  Chemical fumes
  82. 82.  Management  Advice patient on good hygiene  Proper care and maintenance  Do not reuse solutions  Smokers should be warned
  83. 83. Lens Deposition :Rust spots  Appearance:  Small superficial raised spots  Colored orange to black  Can be few to numerous
  84. 84. DISCUSSION Importance of rub and rinse in use of multipurpose contact lens solution. Optom Vis Sci. 2011 Aug PURPOSE : The introduction of contact lens multipurpose disinfection solution (MPDS) that can be used in conjunction with a "no-rub" regimen has simplified lens care requirements. Once adhered to a surface, microorganisms can become less susceptible to disinfection. The aim of the study was to evaluate the effect of various regimen steps on the efficacy of MPDS when used with silicone hydrogel and conventional lenses.
  85. 85. RESULTS: Overall, the greatest efficacy of MPDSs was observed when "rub and rinse" was performed before disinfection with each of the microorganisms tested, regardless of lens type. "No rub and no rinse" steps resulted in a greater load of microorganisms remaining on lenses compared with the other regimens (p < 0.05). When "rinse-only" was performed before disinfection, the MPDS containing polyquad performed generally better (p < 0.05) than MPDSs containing polyhexamethylene biguanide against bacteria. Significantly, less microorganisms were recovered from galyfilcon A than from other lenses (p < 0.05) when MPDSs were used with "rinse-only" step. CONCLUSIONS:  This study has demonstrated that "rub and rinse" is the most effective regimen and should be recommended in conjunction with all multipurpose lens care solutions and all contact lens types, particularly with silicone hydrogel lenses.
  86. 86. Comparative antimicrobial efficacy of multi-purpose lens care solutions using the FDA's guidelines  PURPOSE: evaluated six single-bottle, multi-purpose lens care solutions and a two component lens care system for disinfection efficacy according to the stand-alone primary criteria within the recently published U.S FDA Guidelines.
  87. 87.  RESULTS:  ReNu and ReNu MultiPlus met the FDA's acceptance criteria for stand-alone disinfectants against all challenge organisms: Staphylococcus aureus, Serratia marcescens, Pseudomonas aeruginosa, Candida albicans, and Fusarium solani. Opti-Free Express failed to meet the FDA's stand-alone disinfectant acceptance criteria for S. aureus, S. marcescens and C. albicans and Opti-Free Express with Opti-Free Supraclens failed to meet the acceptance criteria for either S. aureus and C. albicans. Opti-One failed to meet the FDA's stand-alone disinfectant acceptance criteria for C. albicans and F. solani. Both Complete and Solo-Care failed to meet the FDA's acceptance criteria for C. albicans.
  88. 88.  CLAO J. 2001 Jan;27(1):16-22.  Disinfection efficacy of contact lens care solutions against ocular pathogens  PURPOSE:  Three commercially available products labeled as multi-purpose contact lens solutions, one multi-purpose disinfecting solution, and a hydrogen peroxide system were evaluated for antimicrobial activity according to the current International Organization for Standardization (ISO) and the U.S. Food and Drug Administration (FDA) stand-alone procedure for disinfecting products. One multi- purpose solution was selected to assess its antimicrobial activity against two human corneal isolates of Pseudomonas aeruginosa.
  89. 89.  RESULTS:  ReNu MultiPlus (Bausch & Lomb, Rochester, NY), AOSEPT (CIBA Vision Corporation, Duluth, GA), and Opti-Free Express with Aldox (Alcon Laboratories, Ft. Worth, TX) were the only lens care products that met the stand-alone criteria for all required microorganisms within their minimum recommended disinfection time. Of these, ReNu MultiPlus provided the greatest overall antimicrobial activity. ReNu MultiPlus demonstrated a significantly higher mean log reduction of Staphylococcus aureus and Serratia marcescens than Opti- Free Express. ReNu MultiPlus also gave a higher mean log reduction of S. aureus and S. marcescens than AOSEPT, and a higher mean log reduction of Candida albicans and Fusarium solani than AOSEPT, Complete Comfort Plus (Allergan, Irivine, CA), and Solo- Care (CIBA Vision Corp.) (at 4 hours). Both Complete Comfort Plus and Solo-Care (at 4 hours) met the primary acceptance criteria for bacteria; however, neither product possessed enough antimicrobial activity to meet the minimum criteria for yeast or mold. ReNu Multiplus was effective against corneal isolates of P. aeruginosa.  CONCLUSION:  ReNu MultiPlus, AOSEPT, and Opti-Free Express met the requirements of the stand-alone primary criteria for disinfecting solutions. ReNu MultiPlus demonstrated the greatest overall disinfection efficacy, as well as excellent activity against clinical strains of P. aeruginosa
  90. 90.  Contact lens care products effect on corneal sensitivity and patient comfort  PURPOSE:  To evaluate the possible effect of two leading soft contact lens care products on corneal sensitivity, relative comfort, and superficial corneal staining in adapted disposable soft contact lens wearers.
  91. 91.  RESULTS:  Patients habitually using OPTI-FREE Express reported higher comfort ratings than did patients using ReNu MultiPlus. On crossover, patients who initially used ReNu MultiPlus experienced similar comfort when using OPTI-FREE Express, but OPTI- FREE Express users experienced a substantial decrease in comfort when switched to ReNu MultiPlus. Esthesiometry showed significant differences in average sensitivity in favor of OPTI-FREE Express (P=0.0041). Statistical trends supported observed increases in corneal sensitivity when switching to OPTI-FREE Express and decreased corneal sensitivity when switching to ReNu MultiPlus. ReNu MultiPlus was also associated with slightly more corneal staining.  CONCLUSIONS:  ReNu MultiPlus, a biguanide-based contact lens care product, was associated with decreased comfort during midday and end-of-day periods. ReNu MultiPlus was also associated with significant reduction in relative corneal sensitivity compared to Polyquad-based OPTI-FREE Express. Disturbance to normal corneal sensitivity may play a role in contact lens-related dry eye and discomfort. Further investigation is warranted
  92. 92. Care and maintenance of SCLs  SCLs are susceptible to deposits due to:  Lenses are covered by pre-lens film all the times  The tear film undergoes hydration and dehydration cycle as a result of blinking and evaporation bw blinks  Lens is a subject to atmospheric changes and pollutants  Decreased surface wettability is likely to accelerate deposition
  93. 93. Deposits: Complications  Irritation and reduced comfort  Reduced visual acuity  Shortened lens life  Increased potential for infection  Increased incidence of GPC