2. CONTACT LENS FITTING
PRE-FIT CONSULTATION
Complete history
Detailed eye examination
KERATOMETRIC METHOD
Pupil diameter [with IPD scale] is
measured.
HVID is measured.
Corneal diameter is measured.
Radius of curvature is measured with a
keratometer.
3. KERATOMETRIC METHOD
BASE CURVE, back surface of lens.
Rest on cornea responsible for good fit.
Long radius of curvature – flatter base curve.
TD depends upon lid diameter & corneal
diameter OR HVID.
Optical zone should be at least 7 mm.
Posterior surface – Aspheric.
Anterior surface –convex with power.
CONTACT LENS FITTING
4. TRIAL LENS METHOD
Various lens from trial set tried until
appropriate B.C. achieved.
Very tedious and cumbersome
A large trial set has to be maintained
INVENTORY FITTING METHOD
Combination of both above
More time efficient and more convenient to
patient.
CONTACT LENS FITTING
5. FACTORS TO BE KEEP IN MIND
The total diameter should 1-1.5 mm greater
than HVID.
BC should be 0.3-0.6 mm flatter than the
flattest k reading.
DETERMINATION OF LENS POWER
• Spherical power + ½ cylindrical power [ if
cyl is b/w 0.5D to 2.00D ]
• If cyl is < 0.5D Drop cylinder.
• If cyl is > 2.00D , go for toric CL.
6. Lens coverage-uniform
Movement <0.5 mm
Fluctuating vision clears on
blinking
Progressive discomfort on
wearing
Circumciliary congestion
Edge indentation of limbus
Retinoscopic image is fuzzy
T
o correct this-
Increase B.C. by 0.2-0.3
mm
SIGN OF TIGHT FIT
7. SIGN OF LOOSE FIT
⚫ Poor centration
⚫ Movement >1 mm
⚫ Variable vision blurs on
blinking
⚫ Edges stand off , ejection
of lens
⚫ Retinoscopic image blur on
blinking
⚫ To correct this-
Increase T.D. by 0.5-1 mm
Decrease B.C. by 0.2-0.3
mm
8. ⚫After fitting ½ hour to 1 hour should be
given for subside reflex lacrimation.
⚫TOTAL PUPILLARY CAPTURE
should be.
⚫Movement of lens- opposite the
movement of eye
⚫On blinking lens should move upward.
CONTACT LENS FITTING
9. Schematic flow chart of soft contact lens fitting procedure
2. Slit lamp examination
-Corneal coverage
-Edge alignment
-Primary gaze movement
-Centration
-Push-up test
1. Insert trial lens
symptom
-comfort
-visual
Assessment of initial fit
-vision assessment
-visual acuity
-over refraction
Sub-optimal
result
11. CORNEAL EDEMA
⚫Incidence: 2,000,000 new patients
annually .
⚫Causes
⚫ Cataract surgery,
⚫ Trauma,
⚫ Infection,
⚫ or secondary to a genetic defect in the corneal
endothelium.
⚫ To date, there is no effective treatment for corneal
edema besides transplant from a human donor.
HYPER OSMOTIC CONTACT LENS
12. ⚫It enables extraction of fluid from the
corneal stroma, combined with
increased evaporation over the lens
surface.
⚫It is disposable and reusable up to two
weeks.
HYPER CL
13. The dual base
curve combined
with the groove and
the holes inside the
lens creates a
micro-environment
above the center of
cornea that holds
fluid with high ionic
concentration and
thereby absorbs
HYPER CL
14. HYPER CL DESIGN
⚫ The Hyper-CL™ design includes
the following characteristics :
⚫ 1) Two different base
curves, which create a
tear reservoir.
⚫ 2) A peripheral groove including
4-16 fenestrations,
which increase tear
exchange and accessibility.
15. ⚫The application of hyper osmotic drops
result in extraction of fluids from the
cornea, reducing corneal edema
OPERATION PRINCIPLE
![CONTACT LENS FITTING
PRE-FIT CONSULTATION
Complete history
Detailed eye examination
KERATOMETRIC METHOD
Pupil diameter [with IPD scale] is
measured.
HVID is measured.
Corneal diameter is measured.
Radius of curvature is measured with a
keratometer.](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)