A trial lens set contains various lenses, frames, and accessories used to test a patient's vision and refractive error. It includes positive and negative spherical and cylindrical lenses, prisms, an occluder, pinhole, Maddox rod, stenopic slit, and Jackson Cross cylinder. The trial frame holds the lenses and allows them to be rotated for testing. Lenses range in powers from +20 to -20 diopters and cylinders from 0.25 to 6 diopters. Prisms range from 0.5 to 12 prism diopters. The set allows comprehensive refraction and assessment of binocular vision.

1. TRIAL LENS SET OR TRIAL BOX
MEHEDI HASAN

2. TRIAL LENS SET OR TRIAL BOX
• A Trial Lens set is a box or case containing positive (convex) and
negative (concave) sphere and cylinder lenses arranged in pairs, A trial
spectacle frame, thin prism lenses, Occluder, Pin hole, And accessory
lenses etc. are the contents of the case or box and referred to as a Trial
Set.
• According to different usage there are basically 68 lens set, 90 lens set,
104 lens set, 158 lens set, 232 lens set and 266 lens set.

3. TRIAL LENS SET OR TRIAL BOX

4. • Contents of the Trial Lens Set :
1. Spectacle trial frame
2. Spherical lenses
3. Cylindrical lenses
4. Prisms
5. Occluder
6. Pin hole
TRIAL LENS SET OR TRIAL BOX

5. • Contents of the Trial Lens Set :
7. Plano lenses
8. Red and Green filter
9. Maddox rod
10. Stenopic slit
11. Jackson Cross cylinder
TRIAL LENS SET OR TRIAL BOX

6. • Spectacle Trial Frame : It is made up of metallic or plastic frame. It is
light weight with comfortable nose rest. It has usually three
compartments one each for spherical lenses, cylindrical lenses and
occluder. Compartment of cylindrical lens has smooth and accurate
rotation. Nose bridge and temple are adjustable according to patient
face.
TRIAL LENS SET OR TRIAL BOX

7. TRIAL LENS SET OR TRIAL BOX

8. • Spherical lenses : Present in plus (convex) and minus (concave) form.
• Range : + & - 0.12 to + & - 20.00 D
• Variations :
0.25 to 4.00 in increment of 0.25D
4.00 to 6.00 in increment of 0.50D
6.00 to 14.00 in increment of 1.00D
14.00 to 20.00 in increment of 2.00D
TRIAL LENS SET OR TRIAL BOX

9. • Spherical lenses : covex (+) numbered black and concave (-)
numbered red.
TRIAL LENS SET OR TRIAL BOX

10. TRIAL LENS SET OR TRIAL BOX
• Plus(convex) spherical :- Minus(concave) spherical :-

11. • Cylindrical lenses : Present in plus (convex) and minus (concave) form.
Range : + & - 0.25D to + & - 6.00D
Variations : 0.25 to 4.00 in increment of 0.25D
4.00 to 6.00 in increment of 0.50D
TRIAL LENS SET OR TRIAL BOX

12. TRIAL LENS SET OR TRIAL BOX
• Cylindrical lenses :-

13. TRIAL LENS SET OR TRIAL BOX
• Prisms : Prisms displace the image towards apex.
• Range : 0.50,1,2,3,4,5,6,8,10,12
• Prisms are arranged by base apex notation
• Use: To measure small squint
To prescribe prisms in spectacle
Convergence relaxation and reducing diplopia

14. TRIAL LENS SET OR TRIAL BOX
• Prisms :-

15. TRIAL LENS SET OR TRIAL BOX
• Jackson Cross Cylinder : It is actually a combination of two cylinders of
equal strength but opposite signs placed with their axis at 90 degrees to
each other and mounted in a handle. Usually the cross cylinders are of +
& - 0.25 or + & - 0.50.
• It is used for Astigmatic refraction. It refines Cylindrical axis and power of
lens.

16. TRIAL LENS SET OR TRIAL BOX
• Jackson Cross Cylinder :

17. TRIAL LENS SET OR TRIAL BOX
• Occluder : It is a black opaque disc and made up of metallic or plastic
rim.
• It is used for uniocular testing and to intercept light reaching to the eye.

18. TRIAL LENS SET OR TRIAL BOX
• Pin hole : It a black opaque disc with a central pinhole of 1 to 2 mm.
Commonly used to see Best Corrected Visual Acuity.
• Ideal central pinhole diameter is 1.42mm

19. TRIAL LENS SET OR TRIAL BOX
• Stenopic slit : It is made up of black opaque disc with slit aperture. The
slit is usually 1mm in wide. It allows the rays of light to pass through
only by one meridian. It is used to find the axis of the cylinder.

20. TRIAL LENS SET OR TRIAL BOX
• Maddox rod : The Maddox rod is a handheld instrument composed of
red parallel plano convex cylinder lens, which refracts light rays so that
a point source of light is seen as a line or streak of light. Due to the
optical properties, the streak of light is seen perpendicular to the axis of
the cylinder.
• A spot of light viewed through the Maddox rod appears as an elongated
streak.
• The Maddox rod is usually colored red or green.
• It is used to find out the presence of heterophoria or heterotropia.

21. TRIAL LENS SET OR TRIAL BOX
• Maddox rod :-

22. TRIAL LENS SET OR TRIAL BOX
• Red and Green filters : Are used for WFDT (WORTH FOUR DOT TEST)
and Diplopia charting.

23. TRIAL LENS SET OR TRIAL BOX
• Plano lenses : A pair of plano lens are also given in a set of a Trial box.

24. TRIAL LENS SET OR TRIAL BOX
Thank You.