HYDROGEL LENS FITTING AND EVALUATION
I. PATIENT SELECTION
A. Indications
1. Spherical refractive errors
2. Low astigmats
a. Spherical equivalent used as
contact lens Rx
b. Hydrogel toric lenses
3. Patients with lenticular astigmatism
a. Hydrogel toric lenses
4. Athletes, actors, models
a. To eliminate spectacles
b. To look younger
c. To change eye color
d. Easier to wear for sports than
RGPs and spectacles
5. Occasional wear
6. Corneal sensitivity -unable to adapt to RGPs
7. Responsibility - Age restrictions
8. Motivation to wear, care and handle hydrogel lenses
9. Chronic RGP adherence or 3&9 staining
B. Contraindications
1. Inflammation or disease of the anterior segment
2. Any systemic disease which may be complicated by contact lens wear, such as diabetes,
epilepsy, mental incompetency
3. Pregnancy
a. Dry eyes
b. Changes in corneal shape due to
edema and refractive changes due to increased
corneal
thickening
c. Decreased corneal sensitivity
d. Increased tear viscosity, which
increases deposits
e. Exceptions, such as, long-term
wearer who needs replacement lenses
f. First time fits/Patients
experiencing difficulties with dryness, variable vision, etc.
should wait 6
weeks post-partum or 6 weeks after they have ceased breast-feeding
to reduce the
risk of a re-fit.
4. Poor hygiene
5. Lack of motivation
6. Irregular corneas (keratoconus, ocular trauma)-exceptions are cosmetically covered
ocular
trauma.
7. Radial keratotomy
8. Chronic allergies
9. Chronic antihistamine use
10. Giant Papillary Conjunctivitis or Contact Lens-Related Papillary Conjunctivitis (GPC
or
CLRPC)
11. Corneal astigmatism greater than 1D
12. Work environment- dry, dusty, dirty, unsanitary
13. Poor tear quality or quantity
C. Preliminary Evaluation is very important for giving the practitioner a feel for patient suitability
D. Cases
1. A 35 y/o male presents to your office desiring to be fit with contact lenses. He works at a bank and enjoys many sports in his spare time. He is happy with his glasses except that they get in the way when he participates in sports. He finds they are always getting broken from being knocked off while playing basketball, volleyball, etc. He wishes to wear contact lenses for these sporting activities.
2. A 24 y/o female presents to your office to be fit with contact lenses for the first time. Upon taking a case history, you discover she is 3 months pregnant.
3. Your auto mechanic finds out you specialize in contact lenses. He comes to your office desiring to be fit with contact lenses. At his visit, his hands are stained with grease and oil and his overall appearance is one of poor hygiene.
II. LENS SELECTION & FITTING
A. Empirical vs. Diagnostic Fitting
1. "U4 and out the door" philosophy Lens designed by use of K readings and
spectacle Rx - same method as determination of predicted power.
Case 1: Patient has 39.50/40.00 @90 K readings OU and a spectacle Rx of OD -2.00DS and OS -1.75-0.50 X 180. Empirically designed lenses: OD BCR 8.9mm, Rx -2.00D & OS BCR 8.9mm, Rx -2.00D
Case 2: Patient has K readings of OD 43.00D Spherical & OS 42.50/43.50 @ 90 and a spectacle Rx of OD -4.50D, OS -4.50-1.00 X 180. Empirically designed lenses: OD BCR 8.6mm, Rx -4.25D & OS BCR 8.6mm, -4.75D
b. Study done at UM-St. Louis comparing empirical vs. diagnostic fit RGP lenses revealed:
1) Patients
demonstrated greater confidence in lenses which were diagnostically fit.
They appreciated the time the
practitioner took to make sure lenses fit them
correctly.
2) Patients
fit empirically demonstrated lack of seriousness as compared to
diagnostically fit patients.
Diagnostically fit patients were conscientious about
coming to CL progress evaluations.
3) Greater
lens reorders with empirically fit lenses.
c. Predicted lenses dont always work out. There can be a small tear lens under the lens.
2. Diagnostically fit lenses
a. Predicted lens parameters are
selected in the same manner; however, trial lenses
are tried
on the patient to verify that predicted lens parameters are the lens
parameters
to dispense.
B. What type is the patient interested in?
1. Is it realistic?
C. Does the refractive error dictate a certain type of lens?
D. Are there predisposing conditions that warrant a certain type of lens?
1. Dry eyes
2. Prone to deposits
3. GPC
4. Corneal edema
5. Ocular trauma
6. Poor compliance
E. Fitting
1. Insert the patients lenses and allow the lens to settle 10-15 minutes.
2. Assess positioning, coverage & movement
a. Centered
b. Complete corneal coverage and
extending onto the sclera at minimum 0.5mm in all
directions
c. Movement 0.5-1mm in
straight ahead gaze is ideal. As much as 2mm movement
when gazing
superior.
1)
Too tight - Little to no movement, conjunctival drag, negative push-up test
2)
Too loose - Greater than 2mm movement, moving partially off the cornea,
decentered
inferiorly, edge lift inferiorly, slides inferiorly upon upward gaze
3)
Movement varies with lens thickness-Thin lenses move less (i.e., 0.5mm) &
thicker
lenses move more (i.e., 1mm)
4)
Push-up test
3. Determine visual acuity and over-refraction
a. Best sphere
b. Sphero-cylindrical
over-refraction
c. Is acuity stable?
d. Is visual acuity equal to or
very close to spectacle acuity?
4. Over-keratometry will aid in determination of fit
a. Steep fit - clear mire
immediately after blink which then becomes distorted and
blurry
b. Flat fit - Mire distortion which
becomes more distorted on blink
5. Assess Patient Comfort
6. Dispensing out of inventory
7. Parameters required to order lens
a. BCR
b. Power
c. Name of material
d. Name of manufacturer
e. Diameter (?)
f. CT (?)
g. Tint
Example: BCR 8.6mm, Rx -3.50D, CSI Clarity DW, WJ, Diameter 13.8mm, Tint-Visibility tint
BCR 8.7 (Sag I), Rx -4.00D, Optima 38, B&L, Tint-Visibility tint
8. Verify lens vial specifications prior to dispensing
III. DISPENSING
A. Evaluate lens performance
1. Visual Acuity
2. Position
3. Coverage
4. Movement
B. Educate the patient on lens care procedures
1. Provide the patient with written instructions
2. Dont bombard the patient with information
3. Nuggets
a. If minor FB in the eye and
cant remove the lens, push off on the sclera
b. If lens edges stick together,
roll apart with a viscous solution; for example, the daily
cleaner
C. Provide the patient with a wearing schedule
1. First time wearer - 4, 4, 6, 6, 8, 8 hrs. Remain at 8 hrs. until 1 week progress
examination
2. Previous wearer - Full time wear if going from 1 lens to another
D. Teach insertion and removal methods
1. Insertion
a. Fingers dry
b. Make sure the lens is right side
out
c. Inspect lens for damage or
deposits
d. Place lens on sclera and blink
lens into place or place directly on the cornea
2. Removal
a. Slide the lens down onto the
sclera and pinch off the sclera with the pads of fingers
E. Provide an informed consent for patients to sign
1. Specifies that patient was taught insertion, removal & lens care.
2. Patient copy and file copy
3. Telephone number to contact in an emergency
4. Risks
IV. PROGRESS EVALUATIONS
A. Case History
1. Problems/complaints
2. Wearing time (12-14 hours DW/ 3-7 days EW)
3. Solutions
a. Are they compatible?
b. Have they switched?
c. Are they disinfecting?
d. Are they enzyming?
e. Are they compliant?
B. Visual Acuity
1. 20/25 or better ideally
2. Over-refraction (best sphere/sphero-cylindrical)
C. Over-keratometry
D. Slit Lamp Evaluation with lenses on
1. Clear, white eye
2. Position
3. Coverage
4. Movement
5. Lens condition
E. Slit Lamp Evaluation upon lens removal
1. Edema (striae, microcysts, polymegethism)
2. Neovascularization
3. Limbal engorgement
4. Injection
5. Lid eversion
6. Fluorescein evaluation
a. Fluorescein strip
b. Fluorosoft - Large molecule,
less fluorescence
7. Rinse fluorescein out before inserting lenses or wait 2-4 hours before re-insertion.
8. Purging- 3 X 8 hours of distilled water, then place in saline or 2 X 10 minutes of
distilled water and 2 X 10 minutes of saline
a. Peroxide bleaching
F. Keratometry
G. Refraction check
1. Myopic creep
H. Frequency of progress evaluations
1. Daily wear -1 week, 1 month, 3 months, 6 months & every 6 months thereafter
2. Extended wear -1 week DW, 24 hours EW, 3 days, 1 week, 2 weeks, 1 month, 3 months &
every 3 months thereafter
V. Cases
A. Case 1: Patient is interested in obtaining soft extended wear bifocal toric lenses.
B. Case 2: Patient had ocular trauma to the left eye which resulted in a large distorted pupil. The patient is unhappy with the cosmetic appearance. The iris color of the OD is blue.
C. Case 3: Patient desires to wear hydrogel lenses; however, he desires very little care regimen.
D. Case 4: Patient is prone to GPC and protein deposits. He desires new hydrogel lenses. Previous lenses were Cibasoft. Lenses would become deposited after about 6 months.
E. Case 5: Patient returns to your office for 1 month progress examination. Slit lamp evaluation reveals red engorged limbal vessels and conjunctival drag.
VAH 1999
PATIENT EDUCATION CHECKLIST
(Taken from Chapter 10 of text Clinical Manual of Contact Lens,
Bennett & Henry)
Was the patient taught the following tasks:
Lens Insertion ____
Lens Removal ____
Taco Test or other method of determining lens inversion ____
Lens Care:
How to clean a lens ____
How to disinfect a lens ____
When to use saline ____
How to use the enzymatic cleaner ____
When to use a lens lubricant ____
Were the following topics discussed:
Hygiene ____
Swimming with lenses ____
Sleeping in lenses ____
Lens care products to use and not to use ____
Cosmetics ____
Case replacement and cleanliness ____
Lens replacement ____
Normal & abnormal adaptive symptoms ____
Risks of noncompliance ____
Emergency numbers ____
Was the patient reminded to call the office with any
questions regarding symptoms or lens care? ____