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Case Study 1
Initial Summary: This patient known as AB is a 55-year-old
bifocal soft daily wear contact lens patient who presented with
complaints of variable distance vision, inadequate near vision
and difficulty with dry eye problems especially when performing
near tasks for more than a few minutes.
History: AB is very active mother of two teenagers.
She works as a legal assistant and enjoys exercising and gardening
for her hobby.
Anterior Segment Evaluation: Lid, lashes, corneas and
conjunctivae were quiet and unremarkable. Her tear breakup time
was greater than 12 seconds per eye. There were some signs of
peripheral corneal staining related to the soft contact lens wear
which she replaced every two plus weeks.
Presenting Soft Multifocal Lens Design: B&L multifocal, high add
- OD 8.50 -2.25 DS High Add Dist VA 20/25+ Near 20/30-,
Over refraction +0.50 gave 20/20 @ near.
- OS 8.50 -2.75 DS High Add Dist VA 20/20- Near 20/30-,
Over refraction +0.50 gave 20/20 @ near.
Manifest Refraction:
- OD -2.00 –0.37 x 180 20/20 +2.25 Add 20/20
- OS -2.75 –0.25 x 175 20/20 =2.25 Add 20/20
Keratometry:
- OD 42.25 / 42.75 @ 85 D/0
- OS 42.50 / 42.87 @ 90 D/0
Corneal Topography: Maps for both eyes showed no signs of central or
peripheral distortion and the sim Ks were similar to the manual keratometry readings.
Ocular Measurements:
- Pupil Size were 4.0 Mesopic and 5.0 Scotopic, OU
- Corneal Diameters were 12..0, OU
- Palpebral Fissure Size were 10.5, OU
- Lower Eyelid Position was at the lower limbus margin.
Considerations for Lens Designs:
AB needed a lens that would give her stable distance and improved near vision.
She also wanted a lens that would give her all-day comfort and would not dry out
when performing her sustained near vision tasks, which include
computer vision distance and reading text at near.
Treatment: An evaluation of various types and designs of multifocal lenses was considered.
The designs that will give the best performance and vision will be gas permeable
due to the fact that we can get a lens that will give the desired power for
the reading add and full distance correction. The diagnostic lens that gave
the best optics for all the distances was an Essentials III with the CSA Enhancement.
AB was put on dry eye therapy, which included nightly lid soaks and scrubs.
Preservative-free TheraTears HS and AM. She was also instructed to take
omega 3 fatty acid supplement in capsule form daily.
Lens Design: The Essential CSA lens is a spherical base curve lens with an aspheric
peripherical curve system that has an additional aspheric add on the
front surface. This lens is manufactured by Blanchard Contact Lenses of
Manchester, New Hampshire. The result of this design gives a multifocal lens
with adequate distance vision, a good midrange and an effective add of +2.25
for extensive near point tasks.
Lens Parameters:
- OD 7.90 -3.25 9.80 Diam Essentials III CSA +.50 Boston XO
- OS 7.80 -3.50 9.80 Diam Essentials III CSA +.50 Boston XO
Visual Acuities:
- Distance OD, OS & OU 20/20
- Near OD, OS, & OU 20/20
Follow Up Visits: AB achieved good comfort with 12+ hrs. per day of wearing time. She
reported much less difficulty with dry eye symptoms. I feel that lid
soaks and scrubs and omega 3 fatty acid therapy also helped reduce her
symptoms.
Discussion: This case study demonstrates a patient that is a DW soft contact lens wearer
that has attempted to wear a soft multifocal but has difficulty with optics
especially when performing near tasks and problems with comfort related to dry eyes.
- Why this design?
- What alternative approaches could be considered?
- What about other multifocal designs?
- Other materials?
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Case Study 2
Initial Summary: This patient JL is a 57-year-old female.
She has worn gas permeable for 25 years. She had previously worn an
aspheric multifocal design gas permeable but was not satisfied with
her distance vision, especially when driving an automobile.
History: JL is a part-time realtor. Her avocations include tennis,
exercise and traveling. Her general health is unremarkable except for hormone
replacement therapy. Her ocular health is unremarkable. She is currently wearing
single vision GP lenses and wearing single vision reading specs for near tasks.
Anterior Segment Evaluation: Lids, lashes, corneas and conjunctivae
were quiet and unremarkable. Her tear breakup time was greater than 10 seconds,
and no contact lens-related staining was observed.
Presenting Gas Permeable Design: She was currently wearing single vision lenses
and using +2.00 DS reading spectacles over her lenses for reading.
- OD 7.53 BC -4.00 DS 9.20 / 7.80 10.20 / .6 .18 ct F-30 Dist VA 20/20
- OS 7.56 BC -4.00 DS 9.20 / 7.80 10.20 / .6 .18 ct F-30 Dist VA 20/20
Manifest Refraction:
- OD -3.75 -0.50 x 170 20/20-2 +2.00 ADD 20/20-
- OS -4.25 DS 20/25 +2.00 ADD 20/25
Keratometry:
- OD 44.12 / 44.87 @ 89 D/o
- OS 44.50 / 45.12 @ 90 D/o
Corneal Topography:
Maps in axial and tangential format did not show any significant corneal asymmetry.
Ocular Measurements:
- Pupil Size were 4.5+ Mesopic and 5.5 Scotopic, OU
- Corneal Diameters were 12+, OU
- Palpebral Fissure Size were 10.00, OU
- Lower Eyelid Position were 0.50 above lower limbus margin
Considerations for Lens Design:
JL needed a lens that would continue to give her the clear distance vision
that she was getting with her single vision GP lenses. She also wanted to
get clear near vision for reading. She does not use a computer. The needs
indicated the consideration of a translating design GP that would give maximum
distance vision and good near vision. Her previous experience with aspheric multifocals
ruled out the consideration of any of the aspheric designs.
Treatment:
An evaluation utilizing two translating designs. A tangent streak design was the
initial lens used. Excessive lens rotation that could not be eliminated
resulted in distance vision problems. The second lens designed utilized
was a crescent-shaped segment. This design eliminated the distance vision
difficulties due to the fact that lens rotation did not cause the segment
to move into the distance viewing area of the pupil. The lens utilized
was thinner and eliminated upper lid capture and improved lens comfort.
The patient reported that the "lens feels like my single vision lens."
Lens Design:
The Natural Vision Segmented lens design is a mono centric gas permeable lens.
It is manufactured by Con-Cise Contact Lens Co. Inc. of San Leandro, California.
It can be made in any of the currently available approved gas permeable materials.
Improved computer-controlled lathing techniques allow this design to be
made thinner than current prism-ballasted translating GP lenses.
Making the lens in a high dk material such as Boston XO allows for a
greater amount of oxygen to be available to the cornea.
Lens Design:
- OD 7.58 BC -3.75 DS 9.4 / 9.0 , 8.0 OZ / 12.25/.5 .41 CT +2.25 / 3.6 Seg /2.50 BD
- OS 7.56 BC –4.00 DS 9.4 / 9.0, 8.0 OZ / 12.25/.5 .42 CT +2.25 / 3.6 Seg /2.50BD
Visual Acuities:
- Distance OD 20/20-, OS 20/25
- Near OD 20/20-, OS 20/25
Followup Visits:
JL achieved good distance vision and reported very good near vision.
She reported that the new lenses were as comfortable as her
previous single vision lenses. She continued to wear her lenses 13+ hours per day.
Slit lamp evaluation did not show any signs of corneal
changes due to the thicker lens design that are related to
the translating lens design utilizing prism.
Discussion: This case demonstrates the effective use of a translating gas
permeable contact lens to achieve good distance vision and effective near vision.
It shows the importance of considering alternative designs that can work and how
improved manufacturing and design can make a translating multifocal contact lens
fit successful.
- What other designs could be considered?
- What is the importance of material when using translating design lenses?
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