The Snellen chart is the most commonly used eye chart for eye exams. It typically features 11 rows of capital letters, and it can be used to perform an eye exam at home. This is especially useful during the coronavirus crisis, as instructions are provided for using a computer monitor or for printing an eye chart. The Snellen chart was created by Herman Snellen, and it standardized ophthalmology charts.
Before this, each ophthalmologist or eye doctor had their own preferred chart. However, eye charts are not able to detect any diseases such as glaucoma or retina problems. Although eye chart tests can identify refractive errors, they cannot detect any deficiencies in visual abilities or diseases such as glaucoma, cataracts, or macular degeneration. A thorough eye exam is necessary to detect any underlying diseases that may endanger vision and eye health, such as diabetes, high blood pressure, high cholesterol, tumors, autoimmune diseases, and thyroid disorders.
Early diagnosis and treatment of eye conditions is essential to ensuring long-term eye and eye health. For younger children who may not have learned to read or identify letters and numbers yet, ophthalmologists will use graphics with drawings or patterns instead of the Snellen chart. Safe Eyes America is a nonprofit organization dedicated to promoting the delivery of the highest quality medical and surgical eye care to the American public. During an eye exam, your Fishers ophthalmologist will ask you to look through a phoropter and at the Snellen chart placed 20 feet away.
The traditional eye chart features rows of large letters at the top that gradually get smaller as you go down. Acuity charts are used during many types of eye exams, such as eye refraction to determine the best prescription for glasses. The Snellen chart was revolutionary because it allowed a person to provide a standardized prescription from any eye care provider who chose any eyeglass manufacturer, and obtain the same optical lenses to accurately correct their vision. Some clinics do not have 6-meter eye lanes available, so a medium-sized board that subtends the same angles at 3 meters (9.8 feet) or an inverted table projected and viewed by a mirror is used instead.
Your ophthalmologist will prescribe lenses that give you clearer and more comfortable vision. When taking the test, a person covers one eye at a distance of 6 meters or 20 feet and reads aloud the letters in each row starting from the top. This helps ophthalmologists determine if you have an issue with your vision that needs correcting.
