Intermediate Presbyopia (Previous Soft or Monovision Wearer): Susan A. Resnick, OD, FAAO
J.G., a 50-year old homemaker presented for routine contact lens evaluation. She had been a GP lens wearer for over 30 years, the last five years with a mild monovision correction. She reported good distance and intermediate vision, but as an avid reader, was increasingly uncomfortable with near vision. She desired better reading vision without having to use reading glasses.
Her near visual acuity was OU J4. The lenses centered well, exhibiting a lid attached fit with a corneal alignment fluorescein pattern. Her current care system was the Boston Conditioning Solution and the Boston Cleaner (Bausch + Lomb). She wore her lenses 12 to 14 hours per day and had no comfort problems.
Test Procedures, Fitting/Refitting, Design and Ordering
J.G. was right eye dominant. Since increasing the monovision correction was a first option, a +0.75D trial lens was held over her left eye in normal room illumination. Her near acuity improved to J2 but she reported slight diplopia. She also perceived an undesirable reduction in distance acuity.
Her horizontal visible iris diameter (HVID) measured 11.5mm. The patient’s upper lid overlapped the superior limbus by 2mm and her lower lid was positioned 0.5mm above the lower limbus. Her pupil diameter was 4.0mm in normal room illumination.
Slit lamp evaluation:
Corneas, lids, lashes and tarsal conjunctivae were within normal limits OU. Tear Break-Up-Time (TBUT) was 10 seconds bilaterally.
Centered corneal apices bilaterally with an eccentricity value of .50 OU.
These visual and anatomical findings indicated GP aspheric multifocals to be a very suitable option. The Tangent Streak No Line design was selected for trial fitting without topical anesthetic. It is a posterior aspheric design of moderate eccentricity.
The Tangent Streak No Line is ideal for:
- Presbyopic patients with spherical distance needs greater than 1.00D
- Up to 3.00D of corneal astigmatism
- Intermediate distance requirements
- Monovision failures
- Add powers up to +2.25D
- Soft bifocal failures
A well fitted aspheric GP lens will exhibit apical clearance with midperipheral alignment and good and wide peripheral clearance. The true base curve of the Tangent Streak No Line is approximately .16mm steeper than the fitting base curve. The lens should position centrally to slightly superiorly and translate in downgaze. The distance power is in the center of the lens and the add power increases away from the optical center.
OD: -2.75 – 1.00 x 180 20/20 ADD +1.75 J1
OS: -3.00 – 0.50 x 180 20/20 ADD +1.75 J1
OD: 44.00@180/45.25@90 7.67mm/7.46mm
OS: 44.50@180/45.25@90 7.58mm/7.46mm
Trial lens parameters:
|Fitting Base Curve
Lens-to-Cornea Fitting Relationship:
The lenses positioned and translated well, exhibiting slight apical clearance. Initial comfort was excellent. The patient expressed satisfaction with her intermediate vision, which was demonstrated at a computer workstation in the examination room.
The lenses were ordered as above except for a change in the power of the left lens. A –4.00D lens was ordered for a slight monovision effect to enhance near visal acuity. Upon dispensing, binocular acuity at distance and near was 20/20/J1.
Patient Consultation and Education
The patient was told of the likely occurrence of increased post lens wear corneal molding and the fact that her vision might be blurry through her glasses for an hour or two after lens removal. She was also told of the possibility of slightly increased glare when driving at night. Finally, she was educated regarding the potential need for auxiliary reading glasses for very fine print or in conditions of reduced illumination.
The advantages of better binocular vision and the likely significant delay of the need for reading glasses outweighed any of the above concerns and the patient elected to proceed with the refit.
Follow-Up Care/Final Outcome
J.G. was seen two weeks post fitting, again at three months, and semi-annually thereafter. She reported excellent comfort. She was pleased with her vision at all distances. She reported moderate spectacle blur lasting until bed at the three-month visit. An early evening post lens removal refraction was performed at this time and a new pair of glasses was prescribed for use after her she removed her lenses. At one and a half years post fitting, she still did not find the need to use auxiliary reading glasses.
Visual acuity at all follow-up visits with lenses was OD 20/20 OS 20/25 (-0.25sph 20/20). Near visual acuity was J1 binocularly. The lenses centered slightly superiorly in primary gaze and exhibited a mild apical clearance fluorescein pattern. There was 1mm movement with the blink. The lenses translated 2mm superiorly in downgaze. Surfaces remained clean, with good wettability. The corneas remained clear without significant staining. Keratometry and corneal topography values remained stable to within 0.50 D of the pre-fit values in both meridia when rechecked at an early morning appointment prior to lens insertion.
Discussion/Alternative Management Options
Aspheric multifocals are a good option with early-to-moderate presbyopes who do not have a highly critical distance demand. While earlier designs had higher eccentricity posterior aspheric surfaces, many of the newer designs are of low-to-moderate eccentricity which decreases spectacle blur and the need to fit the lens much steeper than K. Several designs are available – both posterior aspheric and anterior aspheric – that allow for selection of the distance optical zone size, as well as providing higher add powers through a modification of the front surface. Patients such as J.G., who have been single-vision GP wearers, are often excellent candidates for aspheric multifocal lenses because the lens designs are thin and the fitting relationship is not much different from their previous lenses.
Alternative management options in this case might have been a translating design or other aspheric as described above. Since J.G. had been a previously successful monovision patient, the Tangent Streak No-Line was selected due to its thin profile, and relatively high effective add without significant reduction of optical zone size. This lens can be ordered in higher Dk materials if desired. The Boston ES was chosen, as this was the material from which the patient’s original lenses were designed and she was doing well physiologically. As J.G.’s presbyopia advances, a slight increase in under-correction of her left eye can be considered.
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