Introduction to contact lens fitting

1. Contact Lens Fitting
1. Introduction to Contact Lens Fitting

2. CONTACT LENS FITTING –
PROTOCOL
Patient screening
Preliminary examination &
measurements
Trial lens fitting
Lens dispensing
After-care

3. PATIENT SCREENING
Establish why the patient wants CLs
Is the patient suitable for CLs ?
Obtain baseline information
Advise patient of their options

4. PRELIMINARY EXAMINATION
AND MEASUREMENTS
 A slit-lamp examination of the anterior
segment.
 Keratometry.
 Corneal and pupil size measurements.
 Assessment of lid characteristics.
 A tear assessment.
 A spectacle refraction and calculation of
the ocular Rx (corneal-plane refraction).

5. KERATOMETRY
 Corneal curvature is the most important
measurement needed before starting CL
fitting.
 Measures only 3 mm of the corneal curvature
 Corneal topography gives the complete
mapping of the cornea.
 KR measurement is sufficient in most of the
fittings.

6. Corneal irregularity also noted.
The reading also tell us about the
degree of corneal astigmatism.
The BC of the CL is determined by
the corneal curvature
measurements.

7. CORNEAL DIAMETER
 HVID – Horizontal Visible Iris Diameter
 VVID – Vertical Visible Iris Diameter
 With a simple millimeter scale ,measuring
the limbus to limbus size both across the
horizontal and vertical lengths.
 The corneal diameter aids in
determination of the total diameter of the
CL.

8. PUPIL SIZE
 The diameter of the pupil is measured by
a simple millimeter scale both in standard
room illumination and low illumination .
 This aids in determining the optic zone
size of the CL.

9. TRIAL FITTING: ROUTINE
 Diagnostic fitting
A diagnostic or trial fitting uses a series of
lenses, chosen on the basis of the findings of
the preliminary examination.
Lenses are assessed sequentially until a
desirable fit is obtained.
The aim of the trial fit is ensure a good lens-
cornea relationship with the design chosen
and to confirm the final Rx required.
 Final lens order

10. TRIAL FITTING: LENS SELECTION
Back optic zone radius (BOZR).
Total diameter (TD).
Water content (for soft contact lenses).
Lens design (lenticular, multicurve,
surface shape, etc.).
Lens type (spherical, toric, bifocal, etc.).
Lens material.
BVP

11. TRIAL FITTING: PROCEDURE
 Initial lens selection.
 Trial lens fitting and vision assessment.
 Subsequent trial lens selection.
If Trial lens required is not available:
Empirical Prescribing

12. TRIAL FITTING: DESIRED RGP
LENS FIT
 Central alignment. (BOZR of the lens closely
matches the central corneal curvature)
 Moderate edge clearance
 Good centration.
 Corneal Coverage (SCL)
 Adequate movement
 Comfort

13. TRIAL FITTING: FINAL LENS
ORDER
 Lens parameters
 Lens material and type
 Special requirements
 Delivery date required

14. LENS DISPENSING
 •Provide information on the lens care regimen
 • Practise insertion and removal techniques
 • Provide information on adaptation
 • Provide information on signs of complications
 • After-care visit schedule

15. AFTER-CARE
 Investigate complaints
 Perform general ocular examination:
 - Over-refraction
 - Slit-lamp microscopy
 - Other tests particular to the patient
 Assess lens fit
 Review lens care regimen
 Schedule next after-care visit

16. THANK U