Bifocal and multifocal contact lenses

1. Presbyopic contact lenses
Rabindra Adhikary
ravinems@iom.edu.np

2. History
 Feeinbloom, 1938
 First reference to bifocal (scleral CL) (New York)
 Williamson Noble (1951)
 Bifocal CL with small convex central near portion on the front
surface
 Freeman 1953
 Pinhole lenses for presbyopic correction
 De Carle 1957
 Concentric bifocal with distance portion in the center (small) for
“Simultaneous Vision” .
 Wesley & Jessen 1957-58
 Concentric Bifocal with distance portion in the Center (larger)
 Jessen 1958
 1st
multifocal CL later named as aspheric bifocal CL in 1961

3. Introduction
 Treatment for
presbyopia, but,
 Some compromise
may be necessary.
 Adaptation is
variable among
patient.

4. Why presbyopic contact
lenses??

Bifocal spectacles/reading glasses
 Head tilting to see near
 Restricted field of view
 Outward symbol of aging
 Switching glasses for reading
 Distorted optics of progressive bifocals
 Weight of spectacles
 Magnification
 Image jump

5. Indication for Bifocal CLs
 Favourable
 Eyelids in normal position
 Average or smaller than average pupil size
 Motivated Patient
 Unfavourable
 Abnormal eyelid position (Very high/low)
 High lid laxity
 Large pupil
 Binocular imbalance
 Residual astigmatism
 High degree of corneal astigmatism
 Narrow palpebral fissure

6. Ideal Candidate Guidelines
Lifestyles
 Occupational requirements
 Cosmetic appearance
 Hobbies and interests
 Avoid “Perfect” vision tasks
Physiological
 -6.00D and +4.00D
prescription (vertex
adjusted)
 Refractive ADDs up to
+2.50D
 Cylinder correction of -0.75D
or less
 Acceptable corneal health

7. Contact Lens Options
1. CL for distances & Single vision Spectacles for near
2. Monovision –

Single vision lenses correcting one for distance & one for near
1. Modified Monovision

Combination of single vision and multifocal CL
1. Bifocal or multifocal CL

Simultaneous vision or Bivision

Translating or Alternating Vision

Multizone bifocals (Aspheric)
1. Non-refractive bifocals

Multiple Pinhole lenses

Spherical aberration correcting lenses

Concentric aspheric’ multifocal lenses’

Diffractive lenses

8. Principle of Fitting Bifocal CLs
 Two Principle
 Simultaneous Vision
 Alternate Vision

9. Simultaneous or Bivision bifocals
 Bifocal lenses in the both eyes
 Can use unequal adds
 Use only the amount of add needed
 Blurred image superimpose in either cases
distance or near focus
 Depends on entrance of light and pupil size
 The size of central distance portion should be
of 2.25 mm to 3.00 mm.

11. Modified bivision
 Bifocal lens in both eyes.
 Over plus one eye at distance
 to increase effective add &
 to improve intermediate vision

12. Alternating vision bifocals
 These bifocals provide alternating
vision
 Distance portion for distance vision
 Lens should move upward while near
work for near vision
 A prism ballast of 1.5 pd base down is
placed to orient the lenses and
sometimes truncated.

13. Translating Bifocal CL Design
The near prescription
is on the bottom.
Truncated to avoid
lens rotation with

14. Monovision
 The most common contact lens treatment for
presbyopia
 uses a single vision contact lens in each eye or, a
lens in only one eye.
 The dominant eye is generally corrected for
distance viewing;
 the fellow eye, for near.
 Modest decreases in contrast sensitivity &
stereopsis occur
 affect the patient's driving & on-the-job performance.

15. Monovision
 Even a mild loss of stereopsis and
report spatial disorientation
 Patients report difficulty performing critical
distance vision tasks.
 The reported rates of success range
from 60 to 80 percent.

16. Modified monovision
 Distance lens in one eye
 Bifocal lens in other eye

17. Multizone bifocals
 Concentric rings alternately powered for
distance & near adjacent zones interfaced
continuously ; no steps
 Large number of distance and near reading
portions, pupil size maintain 50:50 comfort
 Easy to fit – concerned on correct near
addition, good centration & minimal
movement.

18. 8 mm optic zone
Distance
-3.00 -
-2.00 -
-1.00 -
1 2 3 40
Power
mm from center
Power -3.00 / +2.00D
ACUVUE BifocalACUVUE Bifocal power changepower change
Near

19. Multifocal contact lenses

20. Non-refractive Bifocals
 Acts both for distance and near with
either no corrective power in the lens or
only a single vision prescription.
 Pin Hole lenses – only used for academic
purpose
 Spherical aberration correcting lens – a
front aspheric surface help to improve presbyopia
and astigmatism. Useful up to +1.50D.
 Concentric aspheric ‘multifocal lenses’

21. Non-refractive Bifocals
 Diffractive bifocals
 Diffraction cause change in the power.
 e. g. +2.00D (Blue) +3.50D (red)
 But chromatic aberration of the eye
neutralizes it.
 No longer available- Diffrax RGP lens

22. Bifocal choices
 Good distance vision (flying, driving)
 Avoid concentric lenses with small distance
portion in the center
 Prefer for aspheric lenses / prism ballasted
lenses
 Very good near vision (copy editor)
 Rigid concentric lenses with small distance
portion in the center & use of prism ballast

23. Bifocal choices
 Good intermediate vision below eye level
(word processor operator, musician)
 Aspheric bifocal
 Lens with addition used in dominant eye for
distance & non-dominant for near.
 Good intermediate vision above eye level
(chemist)
 Concentric lenses with addition for intermediate
focus in dominant eye.
 Aspheric lenses to both eyes

24. Bifocal choices
 Good intermediate vision above eye level
(librarian)
 Concentric bifocal with peripheral near portion
 Aspheric lenses to both eyes
 Lenses required for social reasons
 Monovision or aspheric lenses in both eyes
 Concentric bifocal or
 Two different powered lenses one in each eye for
intermediate and near vision

25. Measurements
 Much important measurement:
 Pupil diameter
 Position and tightness of lower lid
 Near addition
 Size & shape of segment
 Height of segment above the lower edge of the lens
 Amount of prism ballast and thickness of lower
edge
 Vertical total diameter
 Stabilization

26. Bifocal Candidates
 Good bifocal contact lens candidates
 Average visual demands
 Realistic expectations
 Distance & near correction
 Motivated
 Normal tear & lid function
 Poor bifocal contact lens candidates
 No distance correction
 Not motivated
 Happy with Monovision
 Abnormal tear & lid function

27. Rigid Bifocal- alternating
vision
 Useful for significant corneal astigmatism
 Need for high adds
 Useful for critical near work
 Designs:
 Executive
 Crescent
 Fused segment
 Problem – loose / tight lids
 Need lower lid at inferior limbus

28. Rigid Bifocal- simultaneous
 Concentric
 Aspheric
 Diffractive
 Multi-zone

29. Aspheric soft bifocal lenses
 Center near aspheric bifocal soft lens
 Maximum plus power centrally
 Progressive power effect
 Good for early presbyopes
 Need good centration
 Center distance aspheric bifocal soft lens
 Maximum plus peripherally
 Provide good distance acuity
 Limited add
 Need larger pupils

30. Aspheric Bifocal CL Design
The near and distance
prescriptions are both
near the pupil

31. Concentric soft bifocal CL
 Concentric center near bifocal soft CL
 Pupil size is critical
 Available in different add zones
 Use different add zone for each eye if needed
 Centration critical
 Higher adds available
 Concentric center distance bifocal soft CL
 Less frequently used
 Two rings
 Centration critical

32. Concentric Bifocal Design
The near prescription in the
middle & far is on the outside,
•can be reversed

33. Others
 Diffractive
 Full pupil design
 Multi-zone
 Multiple alternating rings of correction
 Good distance vision especially with lower
adds
 Blending of zones improves intermediate
vision & reduces glare

34. Key to success
 Practitioner should have good and
perfect knowledge
 Detail eye examination is must
 Patient should be properly explained
about adaptation period, cleaning
regiments and duration of the lens

35. Bifocal fitting tips
 Let the lens settle first
 Use loose trial lenses to over-refract
contact lens
 Check vision binocularly
 Avoid checking vision in a dark room
 Push plus
 Consider unequal adds

36. Success Steps for Fitting Bifocal
 Manage patient expectations for
adaptation required for all Presbyopia
correction options.
 Perform current Spectacle refraction with
binocular balanced prescription
 Check Dominant eye by at least two
methods

37.  Calculate Bifocal trial lens Rx
 Round up Near Add power to higher + 0.25 value.
 Calculate Spherical equivalent (Best sphere value)
for toric Rx's.
 Round-up spherical value to higher - 0.25 step
 .
 Apply vertex calculations for Distance sphere
powers

38.  Check Binocular Visual performance –
 Overall subjective performance for distance and
near activities
 Allow adaptation for 30 minutes
 Carefully note down start up trial lens power for
each eye
 If visual performance is "acceptable" for patient
- dispense trial lens for 5 days home trial
 "Acceptable" performance is Binocular
distance vision 6/9 & near N8

39. If distance vision is poor
 Add –0.25DS for distance power of the
dominant eye, if not good.
 Reduce near add by +0.50DSfor
dominant eye, if not good.
 Go to enhanced monovision (Dominant
eye with SV distance Rx and non-
dominant eye with bifocal).

40. If near vision is poor
 Add +0.25DS for near power of non-
dominant eye, if not good.
 Increase near add by +0.50DS for non-
dominant eyes, if not good.
 Increase near add by +0.50DS for both
eyes, if not good.
 Go to enhance monovision (Dominant
eye with bifocal and non-dominant eye
with single vision near Rx)

41. If distance and near vision both are poor
 Add –0.25DS for distance power of
dominant eye and add +0.25DS for
near power of non-dominant eye, if not
good.
 Increase near add by +0.50DS for non-
dominant eye and reduce near add by
+0.50DS for dominant eye
 Go to enhance monovision.

42. Introducing ACUVUE
BIFOCAL
8.5 Base Curve / 14.20 Diameter8.5 Base Curve / 14.20 Diameter
Distance Power: + 4.00 to - 6.00 DDistance Power: + 4.00 to - 6.00 D
- 0.25 D steps including plano- 0.25 D steps including plano
Near Add Power: +1.00 to + 2.50 DNear Add Power: +1.00 to + 2.50 D
+ 0.50 D steps+ 0.50 D steps