BACKGROUND
DK was seen on 7/19/2001complaining of blurry near vision. Previously she wore gas permeable rigid lenses without visual problems
for twenty-four years. DK is on no medications and has no allergies. Family history was positive for glaucoma (paternal grandfather) and
mother had a stroke. This 44 year old computer programmer was forced to use reading glasses at work for manuscript reading. She experienced the
inconvenience of removing the glasses whenever the need to see things at a distance. DK goals were to wear contact lenses for distance,
intermediate and near visual requirements without the aid of reading glasses.
Previous contact lens specifications:
OD
OS
Base Curve
727
728
Center Thickness .13 .13
Overall Diameter 8.2
8.2
Power
-7.87
-7.75
Peripheral Curve 11.00/.4 11.00/.4
Material SGP II blue SGP II blue
Refraction:
O.D. -5.50 Sph Add +1.50 20/20 J2
O.S. -6.00 Sph Add + 1.50 20/20 J2
Keratometry (sim K’s)
O.D. 43.50 X 44.62
O.S. 44.12 X 44.75
IntraOcular Pressure
O.D. 06 mmHg
O.S. 07 mmHg
Pupil Size: 3.5mm (mesopic conditions); 4.2mm (scotopic conditions) Biomicroscopy: Upon lid eversion the tarsal conjunctiva exhibited
a mild Grade 1 injection with mild papillary hypertrophy. The inferior tear meniscus appeared to be clear and adequate in the height to
support contact lens wear. The Tear Break-Up-Time was 14 seconds O.D. and 15 seconds O.S. The Meibomian glands excreted clear fluid upon
gentle expression. No corneal staining was evident with fluorescein application. Lower lid was 2mm below the limbus.
FITTING/TROUBLESHOOTING
The Essential Extra trial lens was applied to each eye and an assessment was made on comfort and visual acuity. A 7.50 Base
Curve lens was selected and placed on both eyes. The diameter was 9.2 and the power -4.00. The lenses were allowed to equilibrate for a
period of ten minutes prior to evaluation. With biomicroscopy lenses exhibited good slightly superior centration and, upon both upward and
straight-a-head gaze, good vertical lens movement was present. Both lenses were also perceived as comfortable by the patient. An over
refraction was performed and loose trial lenses were place over each eye to test the near vision out of the phoropter. The resultant
distance vision was equivalent to her spectacles (i.e., 20/20 O.U.) The initial reading at near point was slightly blurry while the patient
held the reading material in the straight ahead position. A discussion was held with the patient explaining the operation of the bifocal. The
straight ahead position was configured for distance vision and as you look through a lower position of the lens vertically the near power is
increased in the lens which corresponds to a closer reading position. The patient was instructed as the near material is held closer the eyes
have to position lower in the lens. This can be accomplished by either tilting the chin up or holding the near material lower. The lens
centered and was unaffected by the lower lid positioned below the limbus.
Bifocal Contact Lens Specifications: Essential Extra
OD
OS
Base Curve
750
750
Center Thickness .13 .13
Overall Diameter 9.2
9.2
Power
-5.00
-5.75
Peripheral Curve 11.00/.4 11.00/.4
Series
II
II
Distance VA
20/20
20/20
Near
VA
J2
J 2
Material Boston XO ice blue Boston XO ice blue
Biomicroscopy revealed an on K with alignment fluorescein pattern with average peripheral pooling exhibiting good edge lift and pumping
action. The lenses displayed an average lag of 1.5mm with a central position for each lens. If the lens needed go position more superiorly
a flatter base curve would be selected. Conversely, if the lens needed a more inferior orientation a flatter base curve would be selected. The
goal of the fitting design is to have the lens center or slightly superiorly in order for the distant zone aligned centrally so with
downward gaze the lens would move upward to move into the near aspheric zone. The following contact lens design was ordered based on the above
clinical findings.
The Essential Extra lenses were dispensed and a patient re-education program was instituted for proper lens cleaning, disinfection and lens
handling. In addition Giant Papillary Conjunctivitis was explained to the patient and a prescription of Patenol was prescribed.
Our goal was to discuss the importance of lens hygiene and the direct cause of Giant Papillary Conjunctivitis. Boston wetting and
disinfection regime was chosen as the solutions. The positive experience of the re-education program and bifocal refitting turned a
potential contact lens drop out into a successful contact lens patient. Comprehensive patient education communicates the proper methods to
avoid misunderstanding and failure.
At the one week follow-up appointment DK visual expectations and goals were met.
DK was seen in the office the following two years for routine eye examinations and lens polishing. DK was seen in the office on 1/21/05 for
a routine annual examination. Patient experienced no problems with distance although near vision seemed to become difficult and slightly double.
Refraction:
O.D. -4.75 Sph Add +2.00 20/20 J2
O.S. -5.50 Sph Add + 2.00 20/20 J2
Keratometry (sim K’s)
O.D. 43.75 X 44.87
O.S. 44.12 X 44.75
IntraOcular Pressure
O.D. 09 mmHg
O.S. 09 mmHg
Pupil Size: 3.5mm (mesopic conditions); 4.2mm (scotopic conditions) Biomicroscopy: Upon lid eversion the tarsal conjunctiva exhibited
a mild Grade 1 injection with mild papillary hypertrophy. The inferior tear meniscus appeared to be clear and adequate in the height to
support contact lens wear. The Tear Break-Up-Time was 13 seconds O.D. and 14 seconds O.S. The Meibomian glands excreted clear fluid upon
gentle expression. No corneal staining was evident with fluorescein application.
DK was explained that the lens design was adequate although additional bifocal power was needed because of the natural aging
process. The Essential Extra lens design was still adequate with two possible alteration options. We could use the same distant and near
zones with an additional bifocal power on the front of the lens that would not change the distance quality of vision although improve the
near power. (Series II CSA) This option would place a plus annular add on the front of the lens in either a 4.0, 4.3 or 4.6 zone size. Another
option this lens design allows is to decrease the central distance zone resulting in an increase in the aspheric reading zone which has an
affect to improve the near vision. (Series III) By reducing the central distant zone size the patient has additional vertical reading
area to translate into additional near power. The second design modification could reduce the quality of the distance vision especially
when the pupil dilates during night vision creating halos and flare. The patient expectations was to be able to have clear distant and near
vision which ever lens design offered the best chance of success. Although the series III lens design would provided the best near
progressive vision for intermediate vision, the series II CSA lens design was ordered not to change the quality of distance vision. Both
options are contingent on pupil size. The patient was told if more reading power was needed a series III lens or a stronger CSA design
would be attempted. If one design did not meet the patients expectations then the other option would be exchanged with no additional charge.
Bifocal Contact Lens Specifications: Essential Extra CSA
OD
OS
Base Curve
750
750
Center Thickness
.13
.13
Overall Diameter
9.2
9.2
Power
-4.75
-5.50
Peripheral Curve 11.00/.4 11.00/.4
Series II
CSA +0.75 II CSA +0.75
Distance
VA
20/20
20/20
Near
VA
J2
J 2
Material Boston XO ice blue Boston XO ice blue
Biomicroscopy revealed an on K with alignment fluorescein pattern with good peripheral pooling exhibiting good edge lift and pumping action.
The lenses displayed central position for both lenses and good lens movement. The above contact lens design was ordered.
The Essential Extra lenses were dispensed. At the one week follow-up appointment DK described that her near point problems were alleviated
and was able to perform her near and intermediate work adequately.
This case demonstrates the flexibility in prescribing the Essential Extra family of lens products. The lower lid position does not affect
the lens designs fitting options. The Essential Extra lens comes in three different add powers resulting from a mix of decreased
distance zone sizes as well as increased lens e-values. This combination allows the practitioner to fit a wide variety of
patient’s distant, intermediate and near visual requirements with a variety of pupil sizes. When additional nearpoint power is needed
with a patient who has adequate distant and intermediate acuity, a CSA design will accomplish the increase nearpoint goals. By placing
additional add power in an annular configuration on the front of the lens the additive effect will improve near vision as well as a faster
translation into the intermediate power. Controlling both the aspheric zone size on the back of the lens and the annular add power on the
front of the lens gives me the ability to offer this bifocal lens design option to any patient with the goal of bifocal contact lens wear.
Reading Material
An "Essential" Approach to Multifocal Fitting. Robert Davis, OD, FAAO; Brad Cogswell, OD. Contact Lens Spectrum. November 2005
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