trial set
TRANSCRIPT
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.
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
continue..continue..
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.
Continue..
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
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.
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 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.
Continue …Continue …
USES:-To see best corrected visual acuity.Used for macular function test.To analyzed opacity of cornea is central or
Para central.
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 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.
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.