PINHOLE DISK USED IN OPHTHALMIC PRACTICE

 PINHOLE DISK USED IN OPHTHALMIC PRACTICE 

Pinhole disk is a small disk with central opening that prevents peripheral rays of light to pass through. 

The optimal size of the central opening is 1.2mm. Larger size pinholes do not effectively neutralize refractive error and smaller size pinholes significantly increases diffraction and decreases the amount of light entering the eye. 

Some trial lens set also contains multiple pinhole disk which also serves the same purpose. 

The patient finds easier to use multiple pinhole disk as he does not require searching for a single tiny hole.

 The disk permits the examiner to differentiate between the reduced visual acuity caused by refractive error and the reduced visual acuity caused by some pathological changes within the eyes.

 In general visual acuity that is not improved with pinhole disk, cannot be improved by the use of lenses.

OPTOMETRY-SHARP VISION

Optometrist