1. Overview of basics and considerations for fitting
Contact Lenses
Overview of basics and considerations for fitting

2. Outline Solutions Soft Lenses RGP Lenses Contacts and the presbyope
When to use
RGP Lenses
Contacts and the presbyope
Other

3. Contact lens solutions
Soft lens solutions
Rigid gas permeable lens solutions
Compliance always an issue

4. CL history is key How many years How many days/week What brand
Do you use EW
Do you swim
How do you clean
Are you having any problems?

5. Types of soft lenses Spherical Toric truncated Aphakic Extended wear
prism ballast
thin ballast
Aphakic
Extended wear
Bifocal
Bandage lenses
High dK/l
Colored/cosmetic
Colored/prosthetic
Different polymers
Ionic high water
Ionic low water
Non-ionic high water
Non-ionic low water
Newer silicone

6. Types of soft lenses Conventional (sphere/toric)
Keep for a year
Bifocals
Higher powers/cyl
Disposable (sphere/toric/bifocals)
Quarterly
Monthly
Weekly or Two week
Daily

7. Why/Why not soft lenses?
Advantages
Comfortable
Available
Easy to fit
Good for social use
Better for internal cyl
Disadvantages
More risk of infection
Dry out
Prone to rotation (toric)
Get dirty quickly
Noncompliance
Poor Oxygenation
GPC

8. Fitting the spherical pt
Use soft spheres if cyl is < .75D
Get good MR, switch to minus cyl form
Find the SE
Vertex
Keratometry: is K flat or steep
Select material
Select BC/diameter

9. Fitting the Soft Sphere
Place lens on eye, best to wait 15 to 20 min to assess fit
VA (D) and sometimes VA (N)
Over refract to check your power
Assess fit/movement
loose (flat fit)
Tight (steep fit)
Centration
Coverage (at least .5mm all around)
Stability (.5mm in primary, .75mm in upward)
Is pt comfortable?

10. Soft CL problem- sphere
Patient’s Rx is x 090 all cyl is corneal
K’s 44.50/45.50
Patient cannot afford toric lenses- what do you prescribe?

11. Fitting the astigmat with soft lenses
Indications
Cyl >.75D, but if too large may not be successful d/t rotation effects (blinking dynamics)
K plus lenticular cyl, esp ATR
NOT good for pts with irregular corneas
Becherer Twist Test
20deg rot OK=90%
15 deg rot OK=90% with 2 lenses
10 deg rot OK=70% with 3 lenses
5 deg rot OK=pt must accept variable vision with soft toric

12. Fitting the astigmat with soft toric lenses
Methods for lens stabilization
Prism ballast with prism or truncation
Thin zones u/l

13. Fitting method Best to use trial lenses! Select BC first
Then axis (+/- 20)
Cyl power (lower better)
Sph power (least minus)
Wait min.

14. Fitting considerations for the astigmat
Assess fit/movement
loose (flat fit) - will rotate
Tight (steep fit)- reduce rotation but harmful
Centration- same as sphere
Coverage (at least .5mm all around but sometimes bigger is more stable)
Stability (.5mm in primary, .75mm in upward)
Rotation in primary gaze should not exceed 15 degrees

15. Fitting the astigmat with soft lenses
To determine final cl power
Sphero cyl OR then place trial cl power and OR power in lensometer.
LARS (each clock hour is 30 degrees
If lens base rotates to your Left X degrees, Add X to spectacle cyl
If lens base rotates to your right X degrees, subtract X from spectacle cyl

16. Summary
Even when optimally fitted, vision will be worse than with glasses
Consider first lens will be a trial, rarely one lens is sufficient
Failure rate is about 10%

17. Toric Soft CL problem Patient’s Rx: -6.50+2.00x045
K readings:
-What power CL?
- What bc? (choice is 8.7 or 8.2)
- Say CL OR is – 0.50 x 040 what do
you do?
-What if OR is x 090?
- What if lens is rotating 20 degrees nasal?

18. Outline Optics of contacts Soft Lenses RGP Lenses Bifocal Lenses
Fitting procedures

19. Types of RGP’s Spherical Aspheric Toric Bifocal Aphakic
Back surface toric
Front surface toric
Bitoric
SPE
CPE
Bifocal
Segmented
Aspheric and segmented
Aphakic
Reverse geometry
Intralimbal
Mini-scleral
Scleral

20. Anatomy of RGP CL
Bc/power/diameter/optic zone/peripheral curves/ CT/material/color

21. RGP why/why not? Disadvantages Advantages Adaptation Chair time
More Oxygen
Cheaper
Less surface area
Better for dry eye
Masks corneal cyl
Compliance
Rare sleeping
Rare infection
Superior optics
K neo recedes
Less abuse
Disadvantages
Adaptation
Chair time
Misconception
Learning to fit

22. Fitting Philosophies Lid Attachment Interpalpebral
Fit is under the lid
Moves with blink
More comfortable
Less GPC
Interpalpebral
Wide eyes
Must have good recovery
Torics

23. RGP spherical fits High myopia FT contact lens wear
Corneal cyl up to 2.50D (if more, then the lens doesn’t fit well)
Not great for lenticular cyl

24. RGP sphere fit method
Refraction- minus power form, SE, vertex dist corrected as for soft lenses
Keratometry VERY IMPORTANT!!!!!!!!!!!!!!!
Select design- try on if possible
Std v aspheric
Material (high dK means flexure, may need to increase CT .03mm)
Consider pupil size for OZ
Thin flex (intentional flexure)
1D k cyl WTR or ATR residual cyl

25. Fluorescein Patterns too flat wtr alignment too steep
                                                                                                                                                          
Alignment pattern Even pattern centrally with slightly greater clearance peripherally
Spherical BC on 3D WTR astigmatic cornea Horizontal bearing and excessive vertical pooling is observed
                                                                                                                                                          
Alignment pattern Even pattern centrally with slightly greater clearance peripherally
Spherical BC on 3D WTR astigmatic cornea Horizontal bearing and excessive vertical pooling is observed
                                                                                                                                                          
Alignment pattern Even pattern centrally with slightly greater clearance peripherally
Spherical BC on 3D WTR astigmatic cornea Horizontal bearing and excessive vertical pooling is observed
     
Next  >>
More Fluorescein Patterns:     1     2     3
Making Lens Design Changes
Fitting Pearls
     
Next  >>
More Fluorescein Patterns:     1     2     3
Making Lens Design Changes
Fitting Pearls
                                                                                                                                                          
2D flatter than "K" Excessive apical bearing, excessive inferior edge standoff
2D steeper than "K" Excessive peripheral sealoff
1D flatter than "K" Excessive apical bearing, excessive inferior edge standoff
1D steeper than "K" Mild peripheral sealoff
Alignment pattern Even pattern centrally with slightly greater clearance peripherally
Spherical BC on 3D WTR astigmatic cornea Horizontal bearing and excessive vertical pooling is observed
                                                                                                                                                          
2D flatter than "K" Excessive apical bearing, excessive inferior edge standoff
2D steeper than "K" Excessive peripheral sealoff
1D flatter than "K" Excessive apical bearing, excessive inferior edge standoff
1D steeper than "K" Mild peripheral sealoff
Alignment pattern Even pattern centrally with slightly greater clearance peripherally
Spherical BC on 3D WTR astigmatic cornea Horizontal bearing and excessive vertical pooling is observed
Fluorescein Patterns
too flat
wtr
too steep
alignment

26.     
Observe apical clearance and insufficient peripheral clearance
On K 95/84
More alignmet with greater
Peripheral clearance
On K 95/76
Good edge, bit narrow
Bicurve design with a 10.0mm PCR; .5mm wide
An increase in edge clearance can be observed
Bicurve design with a 10.0mm PCR; 1.0mm wide
Insufficient edge clearance can be observed
Bicurve design with a 9.0mm PCR; .8mm wide
Observe greater clearance
12mm PCR, .8mm wide

27. Lacrimal Lens A rgp interacts with the tears
This is why keratometry becomes important
As long as rgp maintains it’s bc, the interface between the lens and the tears is spherical (elimiates astigmatism)
Rgp does not affect internal astigmatism!!

28. Lacrimal Lens Steeper contact creates a + power LL
Flatter contact creates a – power LL
For every BC change, and equal and opposite change of power is needed .05mm=0.25D

29. Lacrimal Lens Problem CL parameters: 7.50/-6.00/95
Need to steepen BC .5D what is new power?
Need to flatten BC by .75D what is new power?

30. Flexure RGPs Flex to the steepest meridian
Wtr cornea, lens steepens in the vertical and slightly flattens in the horizontal.
Measured as toricity with over-K’s
Calculated effect is to lessen the minus power of the LL in the steepest meridian

31. RGP Problem
Rx: -8.50DS K:
What power?
What BC?

32. How to manipulate fit To center the lens steepen bc decrease diameter
To make lens LA fit
flatter bc
increased diameter
Pay attention to the periphery (tear meniscus)
Too tight
Too loose
Insufficient edge clearance can be observed
Bicurve design with a 9.0mm PCR; .8mm wide
Observe greater clearance
12mm PCR, .8mm wide

33. Astigmatism and RGPs Back surface toric
Toricity on back, sphere on front
use with lots of k cyl (2D or more) will provide a better fit to produce alignment
LL is altered, filled with plastic
Higher (n) so greater refractive effect

34. Back surface toric Determine BC first (need accurate K’s)
.25D flatter than flat K
Steep K determined by making toricity ¾ of K cyl (flat BC + ¾ change in BC)
Power is toric and specified for each meridian
LL in flat meridian, leave power for steep meridian unspecified
Make toric peripheral curves to create a round OZ

35. Back surface toric Assess fit- should look aligned
Dot flat meridian to assess rotation- should align with flat meridian and not rotate.
Perform spherocyl OR

36. Bitoric
SPE (spherical power effect) bitoric has both front and back toric surfaces.
Fits like a toric, but has the optics of a sphere when combined with the LL
Indications:
K cyl >2D
Refractive astig w/in .75D of K cyl
Good vision with sphere but poor fit
Lens can rotate around w/o affecting vision

37. Bitoric CPE (cylinder power effect)
Use for eyes with significant K (1.5D) and internal cyl (>.75D).
Back surface corrects the K cyl, the front surface corrects the internal cyl.
The toricity of BC and power are different, so must be stabilized
Lens can’t rotate
Prism.

38. Front surface toric
Signficant internal astigmatism with a relatively spherical cornea (less than 1.5D)
Fits like spherical lens on back, but toric surface on the front. Front power is the cyl that is left over on the OR
Has to be stabilized with prism

39. RGP Problem Rx: -3.00 + 6.00 X 090 K: 42.50/47.75@180 What bc (spe)?
What power?

40. Therapeutic fits Irregular corneas KC Pellucid K lacs
Refractive induced keratoectasia
Post grafts

41. Therapeutic RGP fits Use topography and SLE to assess K
Where are scars
What is steep/flat etc.
Goal is to fill in irregular part with tears
Pick steepest K as starting point
Just fit the lens and then OR to get power

42. Therapeutic fits
Irregular corneas may require larger diameter lenses with multiple peripheral curves
Intralimbal
Miniscleral
Scleral

43. Therapeutic fits Pt expectations critical Vision improves BUT
Lenses take time to get used to
Careful f/u is necessary
Lenses are usually NOT covered by insurance

44. Aphakia
Soft lenses
Rigid lenses

45. CLS and the presbyope Monovision is the easiest/cheapest
Best for those under 40
Without stereo vision needs
Not too picky
OK with part time glasses

46. Monovision fit 48 yo female, OD dominant
RX: x 180 ADD +1.50
-4.25 DS ADD +1.50
What would you prescribe?
Same for lasik/refractive pts

47. Bifocals – soft lenses modified monovision D Simultaneous vision D N N
aspheric

48. Bifocal RGP n
aspheric
aspheric d

49. Bifocal RGP fitting Many different brands Proprietary
Fitting is specific to brand/ type
Many potential changes
Set realistic expectations
Acknowlegde time investment
$350 fit/$300 lenses- self pay

50. CRT Use of high dK,RGP cl at nighttime Reverse geometry design
Advances in topography
Nothing is worn during the day
Moulds the cornea much like braces retainer

51. crt
rgp

52. CRT

53. THE BASICS Details of previous cl wear What are the problems?
When/how do you wear them?
Careful refraction (vertex over +/-4D)
Keratometry or topography
Examination of the cornea, lids, lashes
Dryness…..? MUST FIX.
Pupil size (dim/light)
Palpebral Apeture/ characteristics –tight/loose etc.
Iris Diamter

54. CL fitting Fit the lens Follow up in 2-4 weeks
Tell pts which solutions to use
Refit if needed

55. The Basics Technicians are key to profitability
Insertion/removal training
Lens hygiene teaching
Patient follow up- phone calls
FOLLOW UP IS IMPERATIVE…