jackson cross cylinder- Full Explanation-How To Use

Friends, do you know what is a Jackson cross cylinder? And how to do Jackson cross cylinder and when to do it, so friends, I will tell you in today's blog. How do we use Jackson Cross Cylinder? Friends, before doing Jackson cross cylinder, we should first know that the power of our patient, whether he has cylindrical power or not, and if so, how have you found it? In objective refraction such as auto autorefractometer or retinoscopy, if you have done your patient, then you will come to know that there is cylindrical power in the power of glasses, if a cylindrical power is formed in the eye, then there is an access to that cylindrical power.

The Jackson cross cylinder is a lens used to determine a person's prescription for glasses. The lens has two cylinders, one with positive energy and the other with negative energy, placed at right angles to each other. There is four different axis positions that can be used to refine a person's prescription. 

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The Jackson cross is a great tool for mechanics, but it's important to use it properly and correctly.

Here are step-by-step instructions for using Jackson cross Cylinders:

Identify the person's current prescription:

Before starting, it is important to know the person's current prescription, including the sphere power, cylinder power, and axis position.

Determine the starting point:

Start with the sphere power from the current prescription and add the Jackson cross cylinder with the same axis as the current cylinder. For example, if the current prescription has a cylinder power of -1.00 diopters at an axis of 90 degrees, the starting point for the Jackson cross cylinder would be -1.00/-0.25 x180.

Place the Jackson cross cylinder in front of the person's eye: 

The Jackson cross cylinder is placed in front of one eye while the other eye is covered. Make sure the cylinder is oriented correctly so that the axis lines up with the correct axis position.

Ask the person to look at a distant object: 

The person should look at a distant object, such as a dots on an eye chart.

Determine the best axis position: 

Rotate the Jackson cross cylinder until the person sees the dots as clearly as darker, sharper and circular possible. Take note of the axis position where the dots is clearest.

As you have done through any objective method. How to fit that power in the trial frame on it?

Friends, as you have used objective refraction, whether it is a retinoscope. Should it be that too or should it be an auto refractometer. 

The cylindrical power of your objective refraction is -1.00 DC and the angle is 180 degrees. 

So friends, whenever you do axis refinement in JCC, what is the first thing you have to do?

When you start doing this, you should keep in mind that the chart that should be in front of your patient should be a dot chart. 

And you have to maintain at least six by nine (6/9) or 20/25 visions of your patient. After that we have to rotate the access 20 degrees. Now the first thing we need to do is fix the axes.

Now I've done the 20 degree axis now that I set it to 160 degrees. Now the JCC that you see in my hand, I will put it above the axis in the handle. That is, above 160 degrees, I will keep it in the handle.

Now look carefully, you can see these two dots inside the JCC. There can also be color changes of dots in JCC. There can be white instead of green and there can be black instead of red.

You have to take any one dot as you see, I have accepted the dot here. 

Refine the sphere power: 

Remove the Jackson cross cylinder and adjust the sphere power until the person sees the letter as clearly as possible.

Repeat the process for the other eye: Once the prescription for one eye has been determined, repeat the process for the other eye.

Points to Remember:

• Always make sure the Jackson cross cylinder is oriented correctly so that the axis lines up with the correct axis position.
• Start with the sphere power from the current prescription and add the Jackson cross cylinder with the same axis as the current cylinder.
• Rotate the Jackson cross cylinder until the person sees the letter as clearly as possible and take note of the axis position.
• Refine the sphere power after determining the best axis position.

By following the steps outlined above and remembering the key points, optometrists can use the Jackson cross cylinder to accurately and efficiently determine a person's prescription.

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