Low Vision. Simplified.
6 Step Low Vision Assessment
- Determine goals
- Measure Near Acuity
- Test lighting and glare control
- Measure Distance Acuity
- Calculate Magnification Required to Meet Goals
- Find Devices to Help
Our Low Vision Assessment Worksheet is designed to walk you through the entire process step by step, prompting you for all of the information you'll need to know, and when you need to know it in the process.
1. Determine The Patient's Goals
There is no universal solution for low vision. Different devices and different magnification may be used to help a patient achieve their goals. Below are some common goals your patient may share with you. You may also want to ask them about these as a prompt as well.
|Near Goals||Distance Goals|
|Paying Bills||Seeing Signs|
|Painting Nails||Outdoors Viewing|
2. Measure The Patient's Near Acuity
Snellen charts are not helpful for visual acuity because they make an assumption of distance (20 feet). Measuring near acuity for low vision is best done using the M size. You can use the Tech Optics Printable Near Card or another near card that has M sizes. Record the M size they were able to read, and the distance in centimeters at which they were able to read it.
3. Test Lighting and Glare Control at Near
Does the near acuity or contrast improve under conditions of more or less lighting? Have the patient try reading closer to a bright light. Also have them try yellow and orange filters to see if they have a positive effect on contrast enhancement or visual acuity.
4. Measure Distance Visual Acuity
If you're doing a remote vision assessment, use a 5 foot card in a well lit area. Have the patient use a small tape measure (like the Tech Optics Low Vision Ruler) to measure out 5 feet. You may also want to have them try it with yellow, orange, brown, or grey glasses to see if light affects their distance acuity. Record the lowest line where the patient could read 3 or more letters.
5. Calculate Magnification Required to Meet Goals
Determining goal acuity for distance can be a bit of a challenge. A patient's description of their challenges might not translate to an eye chart. They might say something like "I have trouble seeing faces." Here's a list of some common challenges, and their target acuities.
|Seeing Street Signs||20/30 - 20/40|
|Reading Captions on TV||20/20 - 20/50|
|Seeing Detail of Faces||20/20|
|Improved Recognition of People||20/100|
Magnification Calculator for Distance
Enter the patient's measured acuity from step 4, and the acuity required from the above chart. Record the magnification required.
Near Magnification (Diopters Equivalent)
Rather than magnification, near devices should be selected based on their diopter equivalent. The actual magnification provided by a near device is extremely unpredictable. Diopters are a reliable method for measuring the effectiveness of near-based devices. Enter the M size read, the working distance, and the M size goal into this calculator to calculate diopter's equivalent. Also, if you plan on wearing glasses as a solution, adjust the slider factor in their Near RX.
Record the diopters equivalent for both devices and glasses.
6. Find Devices To Help
After completing the above five steps, you should know:
- The Patient's Goals
- How Much Lighting and Glare Control Help
- The Patient's Magnification Needs at Near and Distance
For Near Work
The most popular devices for near work are handheld magnifiers, stand magnifiers, and glasses. Depending on their goals, consider which of these types of devices may be the most helpful.
The most popular devices for distance use are telescopes. Telescopes can either be hand held, or worn on the face.
For watching TV or sports, a worn telescope is often used. For spot-viewing, like you might in a grocery store or a park, a handheld scope is preferred