Pin Hole Test
Do this test if your Distance Vision Test result is worse than 6/6.
You will first need to make a pinhole eye occluder. This can be simply made by cutting out an 8cm by 12cm piece of card paper and punching a 1.5 mm diameter pinhole through it as shown
To do the Pin Hole Test, the Distance Vision Test is simply repeated with the eye looking through the pinhole.
- Click “Start Test” and a testing chart will be loaded. Measure the height of the biggest number (i.e. 5) in centimeters.
- Multiply the height with 0.72. (example: if the height of the biggest number is 4.2cm, take 4.2 x 0.72 = 3.02 meters. This means you should stand 3 meters away when testing your vision.
- If you wear glasses, do the test wearing your normal DISTANCE prescription glasses, looking through the pinhole.
- Stand at the calculated distance from the monitor and read down to the smallest row of numbers that you can see.
Interpreting the results
This is a very useful test that supplements the distance vision test. It is done when visual acuity is found to be sub-normal i.e. 6/9 or worse. The test is helpful in differentiating whether the sub-normal visual acuity is due to uncorrected refractive errors or due to an eye disease.
If the visual acuity improves looking through the pin hole by one or more rows down the chart then it is likely that the sub-normal vision is probably due to uncorrected refractive errors and the visual acuity should be correctable to normal with corrective lenses.
If the sub-normal visual acuity is not improved at all looking through the pinhole, it is likely that an eye disease is present so an eye doctor should be consulted soon.