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2/22/96 Chapter 9 Contact Lens Fit Assessment page 9-7
9.4 Protocol for Habitual Contact Lens Fit Assessment
In rigid contact lens-wearing CLEK Study patients, the Clinician assesses the
apical and peripheral fit of the patient’s habitual rigid gas permeable contact lenses. The
Clinician enters these data onto the CLEK Examination Form. Fluorescein photographs
are taken of the patient’s habitual contact lens fit, according to the Fluorescein
Photography protocol detailed in Chapter 10 of this Operations Manual.
9.5 Lens Verification Protocol
Accurate analysis and verification of CLEK Study patients’ habitual contact lens
parameters are important.
Table 9-3 lists the Study lens parameters to be verified and the instrumentation to
be utilized. Data are recorded on the CLEK Examination Form.
Table 9-3. CLEK Study contact lens verification.
Lens Parameter
Verification Instrument
Base curve
Radiuscope, keratometer, handheld keratometer
Lens power
Lensometer
Overall diameter
Hand-held 7X reticule
Optic zone diameter
Hand-held 7X reticule
Center thickness
Thickness gauge
9.6 Summary
The assessment of CLEK Study patients involving rigid contact lenses can be
summarized as follows. Steps 1 and 2 are performed on rigid lens-wearing CLEK Study
patients only. Steps 3-7 are performed on all CLEK Study patients.
(1) Assess and photodocument the fluorescein patterns of the patient’s habitual
rigid gas permeable contact lenses. Enter the assessment of central and peripheral fit on
the CLEK Examination Form.
(2) Completely analyze the patient’s habitual contact lenses and enter the
parameters on the CLEK Examination Form. Parameters to be analyzed are base curve
radius, contact lens power, overall diameter, optic zone diameter, and center thickness.
(3) Follow the protocol in Section 9.2 of this Operations Manual to determine the
First Definite Apical Clearance Lens.
(4) Enter the labeled base curve radii of each diagnostic lens applied and record
the apical relationship and peripheral clearance in the spaces provided on the CLEK
Examination Form.