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.
TEST PROCEDURES, FITTING/REFITTING, DESIGN AND ORDERING
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 flat K was selected to avoid excessive central vaulting with the large lens. Lenses of the following parameters were designed empirically and ordered:
Base Curve OAD BVP ct Material
R 7.85mm (43.00D) 9.5 -3.75 .15 HDS
L 7.85mm (43.00D) 9.5 -3.25 .15 HDS
Dispensing:
Prior to lens application the patient was informed we were instilling a drop to help him get used 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 fit was assessed:
Visual acuities with CL’s:
OD 20/30
OS 20/30
Lens fit assessment:
OD: Lens rode high and nasal, lid attached, slightly flat, good to excessive movement associated with moderate tearing
OS: Lens rode somewhat high, lid attached, slightly flat, good to excessive movement associated with moderate tearing
The patient was instructed on lens application and removal techniques (see Care and Handling Tips sidebar), provided a care system and instructed in its use, 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
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 (eg. 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 patient 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 patients Mom reported C.T. was squinting when lenses were in and he was having difficulty with removal. C.T. reported good vision with his lenses. Lenses had been worn up to 12 hours maximum and had been in 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 20/25
Lens fit assessment:
OD: Lens rode high and nasal, lid attached, flat, good movement
OS: Lens rode high and nasal, lid attached, flat, good movement
Impression:
Lenses were reordered smaller and steeper 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:
Base Curve OAD BVP ct Material
R 7.71mm (43.75D) 9.0 -4.25 .09 HDS
L 7.71mm (43.75D) 9.0 -4.00 .09 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 fit assessment:
OD: Lens rode slightly up and nasal, lid attached, near alignment, good movement
OS: Lens rode 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 chief 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.
No Brainer Beneficiaries of Gas Permeable Lenses:
- astigmats (especially with-the-rule)
- progressive myopes
- presbyopes (especially those with astigmatism greater than 0.75 D)
- patient’s with irregular corneas
- keratoconics
- post-refractive surgery patients
- corneal dystrophy patients
Other good candidates:
- patient’s with a small palpebral aperture
- patient’s with high visual demands
- patient’s with physiological compromise from soft contact lens wear
- patient’s who have difficulty handling or are constantly tearing soft lenses
