BACKGROUND
RG, a 44 year old female presented with a history of poor
vision with soft spherical and toric lenses.over a 14 year period. She
had tried four different soft toric designs prior to her visit, but was
unable to achieve rotational stability with any of them.
Manifest Refraction:
OD -3.00 - 1.50 X 105 20/25+
OS -3.50 - 2.50 X 090 20/20-
Keratometry Readings:
OD 46.37 @ 155/47.00 @ 065
OS 46.37 @ 180/45.87@ 090
Original keratometry readings from 14 years previous were:
OD 45.00/44.75 (no axis indicated)
OS 45.25/44.75 (no axis indicated)
Slit lamp Examination:
Neovascularization inferonasally OU; no visible corneal edema,
but hypoxia due to lens overwear suspected.
PATIENT CONSULTATION AND EDUCATION
This patient was advised to discontinue soft lens wear and
return for a GP fitting in two weeks. RG was told that the steepness of
her corneas precluded successful soft toric fitting with stable visual
acuity at this point in time. Advantages of GP lens wear, especially
the increased oxygen transmission and better visual acuity were
discussed. At the follow-up visit, new keratometry readings and
manifest refraction were performed. Residual astigmatism and the need
for a special front toric design for the left eye were explained to the
patient.
Manifest Refraction
OD -3.00 - 0.75 X 105
OS -2.25 - 1.50 X0 90
Keratometry:
OD 45.37 @ 175/46.12 @ 085
OS 45.37 @ 090/45.62 @ 180
Lenses Ordered:
BCR(mm) Power(D)
OAD(mm) Material
OD 7.50
-2.75
9.6
Boston ES
OS 7.55
-2.00 -1.00 X 90
9.6
Boston ES
DISPENSING VISIT
Visual Acuity:
OD 20/20 with effort
OS 20/20
Slit Lamp Examination:
Lid attachment and alignment with fluorescein OU
FOLLOW-UP CARE/FINAL OUTCOME
The lenses were dispensed with the Boston Advance cleaner and
the Boston Original Conditioning solution. RG adapted rapidly and
appreciated the crisp acuity with her new GPs. Initially, she still had
enough accommodation to read with her contact lenses, but over time,
she purchased drugstore reading glasses. Three years after her GP
refit, we suggested trying multifocal GPs.
Manifest Refraction:
OD -2.50 -1.25 X 95
OS -1.75 -0.25 X 88
Add +2.25 OU
Keratometry Readings:
OD: 45.25@90º/45.62@180º
OS: 45.62@90º/45.62@180º
The near-spherical refraction of RG’s left eye
surprised us, and made the fitting of multifocal GP lenses much
simpler. RG was fit with Art Optical Magniclear Plus front surface
multifocals. These lenses are fit conventionally and combine the
principle of simultaneous vision for distance and intermediate with
that of translation for near vision. They have a low negative
eccentricity 7.0 mm distance zone and a spherical near zone that is
controlled independently of the distance/intermediate zones with no
image jump.
This fitter has found that most patients require a significantly
greater add power with these lenses than they have in their spectacles.
Lenses ordered for RG were:
Magniclear Plus:
BCR(mm) Power(D)
OAD(mm) Add(D) Material
OD:
7.50
-2.25
9.5
+3.75
Boston EO 20/20 J2
OS:
7.50
-2.50
9.5
+3.75
Boston EO = 20/20 J2
DISCUSSION, ALTERNATIVE MANAGEMENT OPTIONS
Some fitters hesitate to recommend GP lenses to mature adults
because they think they will not be able to adapt to a rigid material
at this point in life. By leaving these patients in soft lenses, both
visual acuity and corneal health are compromised. Placing a diagnostic
GP lens on astigmatic patients’ eyes will often achieve a
“WOW” factor when they realize how sharp and stable their
vision is. Patients with keratometry values greater than 45.00D in both
principal meridians are often unable to achieve rotational stability
with soft toric lenses. Many of these patients, if they have worn soft
toric lenses (especially low-water-content torics) in the past, will
also show signs of corneal hypoxia, including neovascularization
and even corneal ectasias that resemble early keratoconus under the
base of the prism.
As astigmatic patients enter their presbyopic years they will find soft
lens options even more limited. A multitude of excellent GP multifocal
lenses are available in anterior and posterior surface designs. Some of
the posterior surface designs allow fitters to incorporate an
additional concentric zone of add power on the anterior surface of the
lenses for mature presbyopes. As most patients today spend time
at a computer, this fitter prefers using a multifocal GP to an
alternating vision bifocal design whenever possible.
We explain to our patients that their entire multifocal prescription is
compressed into less than 9.5 mm of space, including the bevels, and
that they might occasionally need to use a pair of low-power
“booster glasses” to see very tiny print. Surprisingly few
GP wearers actually need this supplementary power compared with soft
lens multifocal wearers, but it does emphasize that patients need to
have realistic expectations about presbyopic contact lens correction.
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