By Richard W. Baker, OD, FAAO
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.
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.
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
OD 42.25 / 42.75 @ 85 D/0
OS 42.50 / 42.87 @ 90 D/0
Maps for both eyes showed no signs of central or peripheral distortion and the sim Ks were similar to the manual keratometry readings.
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.
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.
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.
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
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.
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?
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.
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
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
OD 44.12 / 44.87 @ 89 D/o
OS 44.50 / 45.12 @ 90 D/o
Maps in axial and tangential format did not show any significant corneal asymmetry.
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.
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.”
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.
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
Distance OD 20/20-, OS 20/25
Near OD 20/20-, OS 20/25
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.
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?