The document discusses contact lens fitting and the use of hyper osmotic contact lenses to treat corneal edema. It describes the standard process for contact lens fitting including pre-fit consultation, measurement of eye parameters, determining the appropriate base curve and lens power. It also outlines factors to consider for a proper fit and signs of tight versus loose fits. For treating corneal edema, it explains that the unique dual base curve design of hyper osmotic contact lenses creates a micro-environment that absorbs fluid from the edematous cornea through osmosis when used with hyper osmotic drops.

1. CONTACT LENS FITTING

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

10. HYPER OSMOTIC CONTACT LENS
A NEW TREATMENT MODALITY FOR
CORNEAL EDEMA

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