It’s That Simple with Eye Charts from Danish ISOeyes:
With farsightedness and nearsightedness charts from ISOeyes, you can easily screen for both conditions using the two types of charts: the Distance Chart and the Near Vision Tester in combination. The two charts are precisely calibrated relative to each other, so the only difference in the test is the viewing distance. This provides the optimal basis for accurate vision measurements.
Signs of Nearsightedness:
If you achieve better vision results on the Near Vision Chart at a reading distance of 30 cm than on the Distance Chart at, for example, 3 meters, you are likely nearsighted. The degree of nearsightedness will determine if the screening warrants a visit to an eye doctor or optician.
No More Cryptic and Error-Prone Nearsightedness Tests.
This approach to addressing farsightedness and nearsightedness issues is precisely because we are dealing with two test situations that are calibrated in relation to each other. Unlike when the nearsightedness test involves a ‘Jaeger’ card with completely different units of measurement and lines of text, we offer a test where the only difference in the testing environment is the distance to the eye chart.
Read more about nearsightedness and farsightedness below…
How to Determine if You Have Nearsightedness or Farsightedness:
- If you can clearly see the symbols on the red LogMAR 0.0 line (equivalent to 6/6 or decimal 1.0) on the Near Vision Tester at a distance of 30 centimeters, but can only see the line with a value of LogMAR 0.2 or worse (6/9 and decimal 0.63) on the Distance Chart, it suggests that you are nearsighted.
- On the other hand, if you can only just see the symbols on the LogMAR 0.2 line on the Near Vision Tester at 30 centimeters, but achieve a better result on the Distance Chart and can see the line with a value of LogMAR 0.1 or better, it suggests that you are farsighted.
“It’s more important than ever to test for nearsightedness.
Approximately one in five children suffers from nearsightedness, and this number is increasing. Severe nearsightedness is associated with serious eye complications, and the dramatic rise in children’s screen time on iPads and mobile phones has been identified as a significant factor in this troubling development.
Nearsightedness can lead to fatigue, irritation, and headaches due to difficulties in seeing distant objects..
There should be no difference in how distance and near vision charts are constructed!
A chart for measuring nearsightedness (myopia) should fundamentally be constructed in the same way as a standard eye chart. Surprisingly, this simple rule has rarely been followed in the design of near vision charts.
A standard eye chart, like the ETDRS or HOTV, is designed to assess distance vision—typically at a distance of 3 or 6 meters. It measures how well you can see objects from a distance. In contrast, a near vision chart is used to assess vision at close range, typically for tasks like reading or using a computer—usually at a distance of about 30-40 cm, which is the typical reading distance.
Construction of a Near Vision Chart for Myopia:
Symbols, Font Size, and Line Spacing:
There should be no difference from standard eye charts, but the values must also be calculated based on the testing distance. Charts like Jaeger have complicated the process of conducting an accurate near vision screening.
Optical Correction:
If the purpose of the chart is to determine a person’s need for reading glasses or other correction for nearsightedness, the chart can be used with and without reading glasses to assess the difference in clarity.
In Summary:
A near vision chart is designed to assess nearsightedness and is constructed with smaller text or symbols and closer viewing distances compared to a standard eye chart used for testing distance vision. However, they should be constructed to the exact same standards as distance vision charts!
Therefore, it is essential to choose charts that comply with ISO 8596.
ISOeyes presents a near vision testing system (myopia) that is a natural and accurate extension of the ‘distance’ eye charts.
This handy backlit near vision tester from Danish ISOeyes is designed to comply with the revised guidelines from health authorities and operates on a logarithmic scale with CE-approved optotypes in accordance with ISO 8596.
The charts are double-sided and support both letters and symbols, including the Tumbling E, Wekey, OpticianA, and Similar. Regardless of age group, all are covered with the four options on the same handheld eye chart. These charts are calibrated relative to the distance vision charts and configured for a viewing distance of 30 cm.
This double-sided backlit eye chart from ISOeyes is ideal for testing nearsightedness in children and other age groups. With a height of 210 mm, a width of 122 mm, a depth of 15 mm, and a weight of 110 grams, it is easy to use. A charger is included, so it can be used with the provided battery.
The chart accommodates three different optotypes, so there’s no need to switch the chart face when testing different age groups or individuals with specific challenges, such as illiteracy.
When is a person considered nearsighted?
A person is typically considered nearsighted when they have a condition known as myopia. Nearsightedness occurs when the eye cannot focus clearly on distant objects but can focus well on objects that are closer. This usually happens when the eyeball is too long (axial myopia) or the cornea is too curved (corneal myopia).
Symptoms of nearsightedness include:
- Difficulty seeing distant objects clearly.
- Frequently squinting or straining to see distant objects clearly.
- Better vision at close range, such as for reading or screen work.
When nearsighted, light rays focus slightly in front of the retina, causing the focal point to miss the photoreceptors on the retina, resulting in a blurry image.
When is a person considered farsighted?
A person is typically considered farsighted when they have a condition known as hyperopia. Farsightedness occurs when the eye struggles to focus clearly on close objects but is better at focusing on distant objects. This usually happens when the eyeball is too short relative to its optical power, or when the cornea has less curvature.
Symptoms of farsightedness include:
- Difficulty seeing close objects clearly, especially when reading or doing close-up tasks.
- Possibly having trouble focusing on text or objects up close without extending the arms.
- Better vision at longer distances.
Farsightedness can also be corrected with glasses or contact lenses with a positive lens power (plus power) that helps shift the image back onto the retina for clear vision. An eye doctor can determine the exact power needed and recommend the appropriate correction. It is important to consult an eye doctor if you experience symptoms of farsightedness, as untreated hyperopia can cause discomfort and reduced near vision.
When farsighted, light rays focus behind the retina. This is because the cornea and lens’s refractive power is too weak relative to the eye’s length, often due to a shorter eye or incorrect corneal curvature.