MIME-Version: 1.0 Content-Location: file:///C:/D157B22B/FittingCharacteristics&TroubleShooterforSoftLensesHyperlink.htm Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii" Fitting Characteristics & Trouble Shooter for Soft Lenses

Fitting Characteristics & Trouble Shooter for Soft Lenses=

 

When evaluating the fit of a soft contact le= ns, it is essential that, the lens is allowed to remain in the eye long enou= gh to replace the free water with tear fluid from the patient’s eye = and settle down. A minimum of 25 minutes is recommended.

If fitting a low water lens (38%), evaluate the fitting using a low water trial lens, similarly fitting= a high water lens (72% +) use a high water trial lens. =

CHARACTERISTICS

GOOD FIT

STEEP FIT

FLAT FIT

Comfort.

Good.

Good initially.

Poor.

Centration.

Good with complete corneal coverage.

Usually good,

May be decentered,

No movement on blinking.

Poor.

Movement on blinking.

Up to 1.00 mm

Less than 0.50 mm

Excessive, over 2.00 mm

Movement on upward gaze.

Up to 1.50 mm

Little or none.

Excessive, over 3.00 mm

Movement on lateral gaze.

Up to 1.50 mm

Little or none.

Excessive, over 3.00 mm

Vision.

Good.

Poor and variable, momentary improvement on blinking.

Variable, may improve on staring after blinking

Over refraction.

Precise end point, power correlates with BVP of spectacle Rx. <= /p>

Poorly defined end point, positive liquid lens.

Variable, negative liquid lens.

Retinoscopy reflex.

Clear reflex, before and after blinking.

Poor & distorted, central shadow, momentarily improves on blinking. <= /o:p>

Variable, may be clear centrally with peripheral distortion.

Slit lamp after settling (lens in the eye min 25 minutes)

No limbal injection or scle= ral injection.

Conjunctival or limbal injection, scleral indentation.

Localised limbal inject= ion, possible edge standoff

“K” mires (with lens in situ).

Sharp, stable before and after blinking.

Irregular, momentary improvement on blinking.

Variable & eccentric, changing on blinking.

Placido disk.

Regular image.

Irregular image anywhere but at the edge of the lens.

Irregular image, often peripheral occasionally central.

 

Do not use a low powered lens for fitting hi= gh powered correction. A large difference in power means a different lens geometry, which affects the fit.