SOFT LENS MATERIAL FITTING & FOLLOW-UP

EVALUATION

University of Missouri-St. LouisCollege 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 H2O to transport O2

– Limitation to amount of O2 transmitted to cornea

– Corneal oxygen deficiency

2006-01-0004

O2 transport – HEMA materials

2006-01-0004

Silicone Hydrogels Available

Focus Night & Day

O2 Optix & Air Optix Aqua

AV Advance

AV Oasys

PureVision Biofinity

Material Lotrafilcon A

Lotrafilcon B Galyfilcon A

Senofilcon A

Balafilcon A Comfilcon A

Dk 140 110 60 103 101 128

Dk/t 175 138 86 147 110 160

Water content

24% 33% 47% 38% 36% 48%

Powers +6 to -10 +6 to -10 +8 to -12 +8 to -12 +6 to -12 -0.25to -10

BCR 8.4, 8.6 8.6 8.3, 8.7 8.4, 8.8 8.3, 8.6 8.6

Replace Monthly 2-4 weeks 2 weeks 2 weeks Monthly Monthly

Silicone Hydrogels Available

Avaira O2 Optix Custom

Premi O

Material Enfilcon A Sifilcon A AsmofilconA

Dk 100 82 129

Dk/t 125 117 161

Water content

46% 32% 40%

Powers -0.25 to -6 +20 to -20

BCR 8.5 7.4 to 9.2

Replace 2 weeks 3 months 2 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, H2O2, 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

Lens Surface Modifications

• Silicone elastomer materials generally display:– Decreased surface wettability– Increased lipid interaction– Accentuated lens binding

• Require “surface modification”

2006-01-0004

Surface Modifications

O2OPTIX NIGHT & DAY

PureVision ACUVUE Advance ACUVUE 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

2006-01-0004

Surface ModificationsFocus N&D, O2 Optix, Air Optix

O2 Optix Custom

PureVision AV Advance,

AV Oasys

Biofinity, Avaira

PremiO

Ciba Vision Bausch & Lomb

Vistakon CooperVision Menicon

Plasma coating

Plasma oxidation

Internal Wetting agent-

polyvinyl pyrrolidone (PVP)

None Nanogloss

Biofinity

Siloxane molecules attract and bond to surrounding water molecules, continuously wetting and lubricating the material (Courtesy CooperVision)

Increased Modulus

• Mucin Balls

• GPC/CLPC

• SEALs

• Edge Fluting

ModulusMaterial Hydrogel/SiHy Modulus (MPa)

HEMA Hydrogel 0.50

AV Advance SiHy 0.4-0.43

Avaira SiHy 0.5

AV Oasys SiHy 0.6-0.72

Biofinity SiHy 0.75-0.8

PremiO SiHy 0.9

O2Optix/Air Optix SiHy 1-1.2

PureVision SiHy 1.1-1.25

Focus N&D SiHy 1.4-1.52

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

40 60 80 100 120 140 160

O2Optix

Purevision

Oasys

Advance

Mod

ulus

(MPa

)

Dk

SiHDk & MODULUS

Night&Day

An increased Dk is linked with an increase in modulus

biofinity

Courtesy CooperVision

Comfort?

• Silicone hydrogel lens materials are different from conventional HEMA-based materials

• Some patients will experience increased “awareness” when refit

2006-01-0004

Dailies with AquaRelease(Ciba)

AV 1Day Moist(Vistakon)

Water content = weight of water in lens/ total lens

weight X 100

Water Content

• Range of water content 24-79%

• HEMA by itself has 38% water

• Plays a role in determining:

Dk/t, durability, stability, deposit formation, pore size

Silicone Hydrogels

• Hema – Hydrophilic

• Silicone – Hydrophobic

• Dk-Hema = 10

• Dk-Silicone = 250

Dk compared with % Water

27

55

28

55

32

66

26

58

86

47

101

36

138

33

147

38

175

24

0

20

40

60

80

100

120

140

160

180

Dk/t H20

Dk/t and HDk/t and H22OO

Conventional Lenses Silicone Hydrogels

ACUVUE®

OASYS

™

PureV

isio

n®

NIGHT

& DAY

®

Frequen

cy® 5

5.

Bio

med

ics

®

Soflens

® 66

ACUVUE® 2

O 2O

PTIX™

ACUVUE

®

Advance

™

2006-01-0004

FDA Classification

• Group 1 – nonionic, low water

• Group 2 – nonionic, high water

• Group 3 – ionic, low water

• Group 4 – ionic, high water

• Group 5 - ???????

Groups 2 & 4 avoid

• Heat disinfection

• Sorbic acid/potassium sorbate

• Deposit-prone patient

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%

Oxygen Profiles (-3.00 sph.)

2006-01-0004

Examples

• Hydrocurve II 45%, Dk 12, CT .05, Dk/t 24

• Hydrocurve II 55%, Dk 22, CT .05. Dk/t 44

• Optima 38, Dk 8.5, CT .06, Dk/t 14

• Optima FW, Dk 8.5, CT .035, Dk/t 24

• B&L 70, Dk 33.8, CT .1, Dk/t 33.8

Wettability

• Aids in lid closure and comfort

• Contaminants adhere to surface

• Increase sensitivity to preservatives

Internal Wetting Agents

• Polyvinyl pyrrolidone (PVP)

• Polyvinyl alcohol (PVA)

Material Selection• Patients with Ocular Compromise• Refractive Error including astigmatism• Deposit-prone patients• Age• Lens Handling• Part-time Wearers• Compliance• Oxygen requirements• Patient’s Interest• Dry Eye

Soft Lenses for Dry Eye

• Proclear• Extreme H2O• AV Advance• Preference• CSI• Dailies with

Aquarelease• AV 1 day Moist

• O2 Optix/Air Optix Aqua

• Focus N&D• AV Oasys• Purevision• Biofinity• Frequency ?

Why decreased dryness in SiHy?

• Low Dk of hydrogels leads to hypoxia– Decreased corneal sensitivity, decreased tear

flow– Leads to inflammation and ocular surface

damage– Leads to lacrimal damage

Lens Design

• Lathe-cut

• Cast molded

• Spun-cast

• Lathe-cut back & spun-cast front

Optics

• Aspheric lenses to optimize spherical clarity or correct spherical aberration

• Focus N&D, Air & O2 Optix, PureVision, Frequency Aspheric, Biofinity, Avaira

FITTINGPatient Selection

Indications

• Spherical RE• Low astigmats• Lenticular astigmatism• Career enhancing• Occasional wear

• Inability to adapt to GP’s

• Responsibility• Motivation• Chronic GP

complications

Low astigmats

• Spherical equivalent

• Soft Toric

• Aspheric design

Career Enhancing

• Athletes

• Actors

• Models

• Eye Changing Tints

• Fountain of Youth

Responsibility

• Age restrictions

• Participation in the costs of the lens

• 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)(Source: CIBA Vision, data on file)

2006-01-0004

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

Systemic diseases

• Epilepsy

• Diabetes

• Mental incompetency

Pregnancy complications

• Dry eyes

• Refractive changes- Corneal thickness changes

• Decreased corneal sensitivity

• Increased tear viscosity

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 1st 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 12-14 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

CW Wearing Schedule

• New CL patient – Immediate CW

• Follow-up: 1wk, 3wk, 6wk, 6mth

• DW SCL patient – 3 days DW, CW

• Follow-up: 10 days, 3 wk, 6wk, 6mth

• EW SCL patient – 1 week DW, CW

• Follow-up: 2wk, 3wk, 6wk, 6mth

Replacement Schedule

• Daily

• Weekly

• Every 2 weeks

• Monthly

• Every 2 months

• Quarterly

• Traditional/Conventional

Tints

• Handling

• Enhancing

• Opaque

• Opaque wild & crazy

Lens Inversion Markings

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

• 13.8-15mm

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

39.50/40.00 @90 OUOD –2.00D

OS –1.75-0.50 X180

Case 2

OD 43.00 Sph.OS 42.50/43.50 @90

OD –4.50OS –4.50-1.00X180

Fitting

• Insert lenses and let settle 10-15 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

Edge fluting

www.siliconehydrogels.org

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

Follow-Up Evaluations

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 1A 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 1st 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?