Mini trial lens kit

Line up the lines on cylinder lenses with the axis of astigmatism. There may be a dial that helps rotate the cylinder lens. Flip lenses are designed to be hand held in front of the trial lens or customary lenses and test plus vs minus at a set power. Can be used to determine if the customary lenses need tweaking up or down.

They may be monocular or binocular They are also used in vision training. Testing for astigmatism is tricky, and you should master testing for myopia first. Errors such as being off by 90 degrees are common. The JCC Lens has two cylinders at opposite angles and powers. By holding the lens in different ways over a trial cylinder lens, you can determine if the angle or power of the cylinder lens should be changed. This is the part of the refraction test where the doctor is happy if both options are equally blurry.

A stenopeaic slit is just an opaque disk with a slit in it. By putting the slit at different angles and taking standard myopic refraction, one can calculate the angle and power cylinder needed.

The use of a Stenopeaic slit vs a JCC lens seems to be cultural. The stenopeaic slit may be more useful for very high astigmatism. For DIY types, the stenopeaic slit is easy to make at home and is compatible with the simpler cm measurement when a full trial lens kit is not available. The pinhole accessory in many trial lens sets may help distinguish between refractive issues and medical issues. If the vision does not improve or gets worse with use of the pinhole lens, this is an issue that should be addressed by an optometrist.

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