Many people believe that simply reading the lines on a vision chart is enough to be assured of their eye health. However, this test primarily assesses image sharpness and cannot detect all abnormalities in the retina, optic nerve, or other eye structures within the eye.

10/10 vision only reflects a partial aspect of sight

According to WebMD, vision is the ability to see details clearly at a specific distance. A 10/10 result typically indicates a corresponding normal level of vision.

During an eye exam, individuals are usually asked to read letters or identify symbols that gradually decrease in size on a chart. The results indicate how well the eyes can distinguish small details under test conditions, thereby helping to detect refractive errors such as nearsightedness, farsightedness, and astigmatism.

Some individuals with eye diseases may still have clear vision even if certain retinal damages have not yet caused obvious symptoms. Illustration: AI

However, vision encompasses many other functions, including peripheral vision (the ability to see objects to the sides without turning your head), color perception, depth perception, accommodation, and binocular coordination. An individual might read a vision chart clearly yet still experience issues with one or more of these functions.

A standard vision chart does not fully assess the internal structures of the eye. Therefore, a good vision test result cannot replace a comprehensive eye examination, especially for individuals with risk factors or underlying health conditions affecting the eyes.

Glaucoma can cause silent damage

Glaucoma is an eye disease that can progress with few obvious symptoms in its early stages. According to the American Academy of Ophthalmology (AAO), the disease can damage the optic nerve, and those affected often do not notice vision changes until the damage is significant.

In open-angle glaucoma, damage often progresses slowly and may affect peripheral vision before causing a noticeable decline in central vision. Patients can still read books, use phones, or recognize objects directly in front of them relatively normally, even while a portion of their side vision is already impaired.

To assess glaucoma risk, a doctor may check intraocular pressure, observe the optic nerve, measure the visual field, and perform additional tests as needed.

Retinal diseases can be hard to detect

The retina is a light-sensitive tissue layer at the back of the eye, responsible for receiving images and transmitting signals to the brain. Some diseases affecting the retina can progress for a long time before individuals notice significant changes in their vision.

Diabetic retinopathy is one example. Prolonged high blood sugar can damage the small blood vessels in the retina. In the early stages, patients may not notice obvious symptoms, even though changes in the fundus (back of the eye) have already appeared.

Individuals with diabetes must adhere to their doctor's recommended eye exam schedule, even if they have clear vision in daily activities. The timing and frequency of follow-up exams depend on the type of diabetes, duration of the disease, previous exam results, and the individual's overall health.

Some conditions affecting the retina or macular region can impact central vision, detail recognition, or the ability to see straight lines. These changes are not always detected by a standard vision test.

Bao Bao (Compiled)