Presentation on theme: "SOFT LENS MATERIAL FITTING & FOLLOW-UP EVALUATION University of Missouri-St. Louis College of Optometry."— Presentation transcript:
SOFT LENS MATERIAL FITTING & FOLLOW-UP EVALUATION University of Missouri-St. Louis College of Optometry
Advantages Initial comfort Little lag Simple to fit Inventory Quick adaptation Occasional wear Hard to dislodge Difficult to get trapped FB Rarely causes tearing Cosmesis
Disadvantages Bacterial contamination/greater risks with noncompliance Care? Durability Prone to deposits Reduced oxygen permeability with hydrogel materials Quality of vision Difficult to verify Limitations of correction
Materials Chemical monomers linked to form chains of polymers, cross-linked loosely polyHema Add other monomers to improve HEMA MAA, MMA, GMA, PVA Silicone Hydrogels
Monomer Characteristics HEMA – hydrophilic, soft, wettable, low Dk EGDMA – Stable, low Dk MAA – hydrophilic, pH sensitive MMA – Hard, no Dk, machinable, optical clarity, stable NVP – Hydrophilic, wettable, high water uptake, High Dk, pH sensitive
Monomer Characteristics GMA – Wettable, deposit resistant, low Dk PVA – Hydrophilic, high water uptake, Deposit resistant Silicone – hydrophobic, High Dk
The Science Behind the Lenses HEMA-based materials –Positives Easily fabricated into CL’s Relatively cheap to produce Highly flexible Dimensionally stable to changes in pH & temp. –Negatives Reliance on H 2 O to transport O 2 –Limitation to amount of O 2 transmitted to cornea –Corneal oxygen deficiency
O 2 transport – HEMA materials
Silicone Hydrogels Available Focus Night & Day O2 Optix & Air Optix Aqua AV Advance AV Oasys PureVisionBiofinity Material Lotrafilcon A Lotrafilcon BGalyfilcon A Senofilcon A Balafilcon AComfilcon A Dk Dk/t Water content 24%33%47%38%36%48% Powers+6 to to to to -10 BCR8.4, , , , ReplaceMonthly2-4 weeks2 weeks Monthly
Silicone Hydrogels Available AvairaO2 Optix Custom Premi O Material Enfilcon ASifilcon AAsmofilcon A Dk Dk/t Water content 46%32%40% Powers-0.25 to to -20 BCR to 9.2 Replace2 weeks3 months2 weeks
Other Dk/t Values Soflens 38 = 21 AV2 = 20 Focus Monthly = 15 Focus Dailies = 27 SF 1 Day = 16 Proclear = 30
Pure Vision (B&L) Performa surfacing process Do not use abrasive cleaners, H 2 O 2, Miraflow Glassy islands Available in toric & multifocal DW/EW/CW
Focus Night & Day, Air Optix Aqua O2 Optix & O2 Optix Custom (Ciba) No restrictions on care solutions Plasma coating Surface chemically uniform Uniformly coated with hydrophilic polymer N&D DW/EW/CW, Air & O2Optix DW/EW, O2 Optix DW, Air Optix for Astigmatism
Acuvue Advance & Oasys (Vistakon) AV2 design, UV blocker No coating, Hydraclear wetting agent on surface and throughout lens AV Adv. DW, Oasys DW/EW Toric and Multifocal
Biofinity & Avaira (CooperVision) Company reports no surface treatment or wetting agents Aquaform comfort science DW at this time
Surface Modifications O 2 OPTIXNIGHT & DAY PureVision ACUVUE AdvanceACUVUE OASYS Permanent, chemically bonded plasma treatment for a smooth, continuous surface Surface made up of silicate islands that do not completely cover the surface No permanent plasma treatment All photos 5 x 5 micron resolution
Oxygen Permeability Increases with water content in HEMA lenses Increases as water content decreases in Silicone Hydrogels Oxygen transmission increases with decreases in CT Dk ranges 8.3 to >100 Tear exchange 1-2%
Career Enhancing Athletes Actors Models Eye Changing Tints Fountain of Youth
Responsibility Age restrictions Participation in the costs of the lens
Essentially every other SCL patient entering your office desires the freedom and flexibility of sleeping in their lenses, at least occasionally. Don’t want to sleep in their lenses 54% Want to sleep overnight in their lenses occasionally 21% Variability in Lifestyle Source: CIBA Vision, data on file, % Want to sleep overnight in their lenses on a regular basis
Most who sleep in their lenses do so frequently – average is 21 nights/month 41% of those sleeping in their lenses do so for more than 7 nights continuously –Many (28%) are wearing lenses not approved for such use 84% of soft contact lens wearers accidentally fall asleep or nap with their lenses Sleeping in lenses (Source: CIBA Vision, data on file)
Contraindications Inflammation/Disease of Anterior Seg Systemic disease Pregnancy Poor hygiene Lack of motivation Irregular cornea RK Chronic allergies Chronic use antihistamines GPC Astig.>1D Work environment Poor tears
Preliminary evaluation is important for determining patient suitability
Case 1 35 y.o male banker Desires CL’s for occasional sports activities
Case 2 24 y.o female Wants CL’s 1 st time 3 months pregnant
Case 3 Auto mechanic Wants CL’s Poor hygiene
Lens Selection Lens Type DW, FW, EW, CW Replacement schedule Tints What is the patient interested in?
DW, FW, EW, CW Wear hours a day Remove daily Occasional overnight wear Full time overnight wear 7 days/6 nights 30 day wear
Educate and Set Proper Expectations- Making the switch Oxygen Transmission Corneal Health Modulus Replacement schedule Discuss going from hydrogel EW to SiHy EW or CW Give the patient 1-2 weeks
CW Patient Education Use appropriate solutions for SiHy’s Rub the lenses to clean, except ClearCare Do not swim in lenses and do not sleep in lenses after swimming Clean & disinfect upon removal Need back-up glasses with updated Rx Examine every 6 mths. Bring glasses and solutions to visits Remove when ill and do not sleep in them Must be 100% healthy to wear CW Remove if dirty or FB sensation to clean & disinfect Replace with fresh, clean lenses each month Showering in lenses?
Even in a BMW, you need to slow down when it is icy. - Dr. Ghormley
BCR 4-5D flatter than flat K Steepest BCR = flat K >45D Middle BCR = flat K 41-45D Flat BCR = flat K < 41D
Lens Diameter HVID +2 = Lens Diameter mm
Lens Power Vertex > + 4D Spherical equivalent for < 1D cyl Residual astigmatism = Refractive cylinder
Center Thickness Greater minus – Thinner Greater plus – Thicker Thicker lenses are easier to handle Thinner lenses provide greater oxygen transmission
Fitting Evaluation Empirical vs. Diagnostic
Case 1 OU OD –2.00D OS – X180
Case 2 OD Sph. OS OD –4.50 OS – X180
Fitting Insert lenses and let settle minutes Assess position, coverage and movement Centration- centered Complete corneal coverage 0.5-1mm lag, Push-up test
Too tight Conjunctival drag Negative push-up test No movement
Too loose > 2mm lag Moving off cornea Decentered inferiorly Edge lift Slides inferior on superior gaze
Determine visual acuity and lens power by best sphere & sphero-cylindrical over-refraction
Over-keratometry Flat Fit Mire distortion which becomes more distorted on blink Steep Fit Clear mire on blink which becomes distorted
Assess Patient Comfort Dispense out of Inventory/Trials? Parameters required to order (BCR, Rx, Material name, diameter?, CT?, tint) Verify lens specifications prior to dispensing
Patient Education Provide written instructions Don’t bombard them with info Give them nuggets Provide wearing schedule Teach I & R Provide Informed Consent Teach lens & case care Teach how to open blister pack
Nuggets Use a rewetting drop prior to removal Dial toric lenses prior to removal FB under lens, pull onto sclera and blink back on Use viscous solution like daily cleaner to unroll edges
Lens Insertion tips Fingers dry Make sure lens is not inverted Inspect lens Place on sclera or directly on cornea
Lens Removal tips Slide the lens off onto sclera Pinch off with the finger pads
Informed Consent should cover: Specifies patient taught I&R, care Emergency phone number Risks Dr. copy & patient copy
Progress Evaluations Case Hx VA Over-Ks SLE lenses on & off K’s with lenses off Refraction RTC schedule
Case History Problems/complaints WT Solutions: Are they compatible? Have they switched? Are they disinfecting, enzyming, cleaning? Are they compliant?
SLE with lenses Clear, white eye Position Coverage Movement Defects in the lens
SLE without lenses Edema (microcysts, striae, polymegethism) Neovascularization Limbal engorgement Injection Lid eversion Fluorescein Evaluation (Rinse out)
Case 1 A patient is fit in a Frequency 55 lens, base curve radius of 8.4mm, worn DW. It is a group 4 lens with a water content of 55%. It comes in base curve radii of 8.4, 8.7 & 9.0. RTC in 2 wks with trial lens. Upon the return visit, engorged limbal vessels and conjunctival drag. What do you plan to do?
Case 2 Focus Monthly wearer, DW basis Group 4, BCR 8.6 Using Complete, appears compliant but has deposits Name other options for this patient?
Case 3 Your patient works at a computer at work. She uses frequent rewetting drops. She experiences dryness. What might be helpful for her?
Case 4 Patient is wearing AV lenses 2-3 weeks continuously. Some signs of edema. What lens options might you want to discuss with the patient?
Case 5 Patient is interested in obtaining soft extended wear tinted bifocal toric lenses.
Case 6 Patient had ocular trauma to the left eye which resulted in a large distorted pupil. The patient is unhappy with the cosmetic appearance. The iris color of the OD is blue.
Case 7 Patient desires to wear soft lenses; however, he desires very little care regimen.
Case 8 Patient is being fit for CL’s for the 1 st time. She loves monovision; however, she has trouble seeing the lenses when handling. What would you do for her?
Case 9 Patient was fit in Focus Night & Day. They previously wore AV 2 for 1-2 weeks EW. They return for a 1 week check. They are complaining of lens awareness. SLE findings are normal.
Case 10 Patient is wearing PureVision lenses. At their 2 week follow-up visit you notice a mild coating on the lenses. The patient is using Aquify with their lenses. Any thoughts on what might be happening?