Common "Snellen Chart" queries answered by top doctors | iCliniq

Snellen Chart

A Snellen chart is an eye chart used by ophthalmologists to measure visual field acuity. This chart consists of 11 rows of the English alphabet written in capital letters; the first row depicts larger letters, and the size of the letters decreases with each row. In a Snellen chart test, the patient will be asked to stand 20 feet away from the chart and read the letters without glasses or lenses. The doctor measures the visual acuity by analyzing how efficiently the patient reads the letters.

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All the answers published in this website are written by verified medical doctors, therapists and health experts. The Content has been moderated by iCliniq medical review team before publication. Post your medical clarifications on iCliniq by choosing the right specialty and get them answered. Your medical queries will be answered 24/7 by top doctors from iCliniq.

Why is there a difference between axis given by doctor and autorefractometer?

Query: Hi doctor, My cylindrical power in the right eye is -0.5 D and the axis of the power is coming 30 in the auto refractometer. But, my doctor prescribed me the axis of the power 180, and I could see even the smallest letters in the Snellen's chart with that glass. So, I want to know why there is a hug...  Read Full »


Dr. Rasmi Abo Touk Rifai

Answer: Hi, Welcome to icliniq.com. You see, ten by ten or six by six mean the glasses are good and suitable. For the difference, actually, the difference is 30 and not 150 and I will explain it to you. The cylinder and its axis is a piece of the rod without base and head, both ends are same. Now imagine ...  Read Full »

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