TRIAL CASE

PRENTER:- PARESH PRENTER:- PARESH MHATREMHATRE

MODERATOR:- KUNAL MODERATOR:- KUNAL KISHORKISHOR

TRIAL CASE

It contains the set of spherical and cylindrical lenses of known power.

Components present in Trial set areo Spherical lenses.o Cylindrical lenses.o Prism.o Accessories.

Reduce APERTURE LENSES

Always Plano convex & Plano concave. Diameter of the lens is 20mm.These lenses probably gives the best

approximation.

Use of the lens is neutralize the spectacle lens with their opposite sign.

FULL APERTURE LENSES.

Full aperture:

Always Bi-convex & Bi-concave. Diameter of the lens is 38mm.

Spherical lenses

Present in plus and minus formRange: +& -0.12D to +& - 20.00D.Variation:- 0.25 to 4.00D in increment of 0.25D 4.00 to 6.00D in increment of 0.50D 6.00 to 14.00D in increment of 1.00 D 14.00 to 20.00D in increment of 2.00D

Cylindrical lenses

Present in plus & minus form.Range:- +&-0.25D to +&-6.00D.

Variations:- 0.25 to 3.50D in increment of 0.25D 3.50 to 6.00D in increment of 0.50D

Principle:-

Displace image towards apex.

PRISM

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Prisms up to 10 prism diopter with addition of 15to20prism diopter.

Range:-0.50,1,2,3,4,5,6,8,10,12 prism dioptre. It is Plano thickness gradient prism.

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There are mounted with base apex notation.

Use:To measure small squint. To prescribe prism in spectacle.

ACCESSORIES

Trial frame

Jackson cross cylinder

Occluder

Pin hole

Stenopic slit

Maddox rod

Red & Green filter

Trial frameTrial frame

TRIAL FRAMETRIAL FRAME

It is made up of metallic/plastic frame.

Ideal trial frame features are:-

1.Light weight with comfortable nose rest

2.At least 3 compartment one each forspherical lensescylindrical lensesoccluder

Continue…Continue…Compartment of cylindrical lens has smooth and

accurate rotation.

Properties of ideal frame:-

Non allergic material.Nose bridge & temple are adjustable according

to patient face.

JACKSON’S CROSS-CYLINDERJACKSON’S CROSS-CYLINDER

The cross cylinder is a combination of two cylinders.

Their axis at right angles to each other and mounted in a handale.

The commonly used cross cylinders are of

+&-0.25 or +&-0.50.It is used for Astigmatic refraction.

Continue..Continue..The cross cylinders usually used to refine

cylindrical axis and power of lens.

OCCLUDEROCCLUDER

It is black opaque disc & mounted in metal/plastic rim.

It is used for uniocular testing and to occlude light reaching the eye.

PIN HOLE

PIN HOLEPIN HOLEPinhole:-It is black opaque disc with central pinhole

of 1 to 2 mm.Ideal central pinhole diameter is 1.42mm.

PRINCIPLE:-It allowed only one ray of light to passed

through along the principle axis of eye.

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USES:-To see best corrected visual acuity.Used for macular function test.To analyzed opacity of cornea is central or

Para central.

STENOPIC SLIT

STENOPIC SLITSTENOPIC SLITIt is made of black opaque with slit aperture.Slit aperture with 15mm length and 1mm width.

It allowed ray of light to passed through only 1 meridian.

Continue..Continue..USES:-To record V/A in 1 meridian.To find axis of cylinder.To find principle meridian.

MADDOX ROD

MADDOX RODMADDOX ROD

It is the series of high power convex cylinder mounted with their axis parallel to each other.

This available in red and green colours.

Principle:-It convert spot light into a line.

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USES:-To diagnose & measured phoria.To measure conversion.

GREEN & RED FILTERS.GREEN & RED FILTERS.

GREEN & RED FILTERS.GREEN & RED FILTERS.

Green & Red filters:- This are red glasses of 640nm & green 535nm

wavelength.Red filter in front of the RE and Green filter for the

LE.

Principle:-This dissociate the eye using colour sense.

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In WFDT. (Worth for dot test)Diplopia charting

Thank you