BACKGROUND
C.T. was a 7 year old whose mother was quite concerned about
C.T.’s progressive myopia. Prior use of bifocal spectacles
had failed to have a significant impact. C.T.’s father was a
-7.00D myope who wore GP contact lenses.
C.T.’s mother was advised that GP contact lenses
and corneal reshaping devices may help slow further myopic development.
In addition, either of these devices would be much easier for C.T. to
apply and remove from his eyes than soft lenses in light of his narrow
aperture size (see photo). The mother elected to pursue GP contact
lenses.
Example of narrow apertures favorable for GP lenses
TEST PROCEDURES, FITTING/REFITTING, DESIGN AND ORDERING
Manifest Refraction and Visual Acuity:
OD -4.25 - 0.25 x 069 20/25
OS -3.75 DS
20/25
Keratometry:
OD: 43.50 @ 042/44.25 @ 132
OS: 43.50 @ 152/44.25 @ 062
Lens selection:
Although C.T. had a narrow aperture, a large (9.5 mm) lens
diameter was selected to promote lid attachment and thereby minimize
interaction between the upper eyelid and the lens edge. A base curve
0.50D flatter than "K" was selected to avoid excessive central vaulting
with the large lens. Lenses of the following parameters were designed
empirically and ordered:
BCR
OAD
BVP
CT
Material
OD 7.85mm
(43.00D) 9.5mm
-3.75D
.15mm Paragon HDS
OS 7.85mm
(43.00D) 9.5mm
-3.25D
.15mm Paragon HDS
BCR = Base Curve Radius
OAD = Overall Diameter
CT: Center Thickness
Dispensing:
Prior to lens application the patient was informed we were
instilling a drop to help him get accustomed to his new lenses and one
drop of Fluress was instilled in each eye.
After lenses were applied, room lights were dimmed and the
patient was instructed to keep his chin up, but look down, to minimize
upper lid awareness of the lenses. After 10 minutes the
lens-to-cornea fitting relationship was assessed:
Visual Acuities with Contact Lenses:
OD 20/30
OS 20/30
Lens-to-Cornea Fitting Relationship:
OD: Lens positioned high and nasal, lid attached,
slightly flat, good-to-excessive movement associated with moderate
tearing.
OS: Lens positioned somewhat high, lid attached,
slightly
flat, good -to-excessive movement associated with moderate tearing.
PATIENT CONSULTATION AND EDUCATION
The patient was instructed on lens application and removal
techniques (see Care and Handling Tips sidebar), provided a care system
and instructed in proper usage, and given a wearing schedule as follows:
Day 1
2 3
4
5 6
7 8
9
Hours of
wear 4
7
10 12 Hold at 12 hrs
until next visit
SIDEBAR: Care and Handling Tips
1. With young patients it is especially important to emphasis
good hygiene, such as thorough hand washing prior to lens handling.
2. Instruct the patient to dry hands with a lint free towel.
If fingers need to be dried during the application process, do so by
wiping the fingers on the back of the opposite hand to minimize the
risk of getting lint on the fingertip and in the eye.
3. Instruct the patient always put the same lens in first (e.g., the
right lens) to avoid mixing and to “pay attention”
with their left eye as they apply the lens to the right eye and visa
versa.
4. Instruct the patient to “gently place”
the lens on the eye. This is important because young patients
often try to “pop” the lens on the eye, which is
generally not successful. Placing the lens on the eye is more
controlled, creating less apprehension and resulting in greater success.
5. Once the lens is applied, instruct the patient to look
down before blinking. This helps prevent lens ejection or
mislocation on the eye.
FOLLOW-UP CARE/ FINAL OUTCOME
Follow-up Visit #1 (10 days post-dispensing):
The patient’s mother reported C.T. was squinting
when lenses were in and he was experiencing difficulty with
removal. C.T. reported good vision with his
lenses. Lenses had been worn up to 12 hours maximum
and had been worn for 3 hours at the time of the visit.
Spherical Over-Refraction and Visual Acuities with Contact
Lenses:
OD: +0.25 D 20/25
OS: Plano
20/25v
Lens-to-Cornea Fitting Relationship:
OD: Lens positioned high and nasal, lid attached,
flat, good movement
OS: Lens positioned high and nasal, lid attached,
flat, good movement
Impression:
Lenses were reordered smaller in diameter and steeper in base curve
radius to improve centration and promote easier removal. The
right lens was ordered 0.75D steeper but the power was adjusted -0.50D
due to the +0.25 over-refraction. The left lens was also
ordered 0.75D steeper and power was adjusted -0.75D. Also, a
thin lens design was ordered to enhance comfort.
New lens parameters:
BCR
OAD
BVP
CT
Material
OD 7.71mm
(43.75D)
9.0mm
-4.25D .09mm Paragon
HDS
OS 7.71mm
(43.75D)
9.0mm
-4.00D .09mm Paragon
HDS
Lens dispensing #2:
The new lenses were applied and allowed to settle for 10
minutes. C.T. reported “These feel
better”.
Spherical Over-Refraction and Visual Acuities with Contact
Lenses:
OD: plano
20/25
OS: plano
20/25
Lens-to-Cornea Fitting Relationship:
OD: Lens positioned slightly up and nasal, lid
attached, near alignment, good movement
OD: Lens positioned slightly up and nasal, lid
attached, near alignment, good movement
Lens application and removal techniques were reviewed and the
patient was instructed to return in two weeks.
Follow-up visit #2 (One month later)
C.T. returned reporting good vision, improved comfort and lens
handling with average wearing time of 10 hours per day. No
significant changes in clinical performance were noted and the patient
was released for follow-up in 6 months.
DISCUSSION/ALTERNATIVE MANAGEMENT OPTIONS
Soft contact lenses were not recommended for the patient because the
primary motivation for contact lens correction was to help slow myopic
changes and soft lenses are ineffective in this regard. Additionally,
GP lenses are much easier to apply and remove from the eye in the
presence of a small aperture.
When working with a young patient it is particularly important to
project a calm demeanor and approach the fitting process methodically.
Keeping the young patient informed with each step helps calm fears and
improves cooperation.
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