The effect of pinholes of different sizes on visual acuity under different refracting states and ambient lighting conditions*

Abstract

Purpose: The purpose of this pilot study was to investigate the effect of different size pinholes on visual acuity (VA) at near (0.4 m) while various factors were altered. The alterations made involved accommodation and illumination. Method: Four subjects were selected and their ages ranged from 7 to 14 years. Subjective refractions were performed and then near visual acuities were measured at 0.4 m under two different lighting conditions (460 lux and 1 lux) by adding stigmatic (or spherical) lenses of positive and negative powers in front of pinholes of diameters 1.5 mm and 2 mm. Results: The results showed that there was an improvement in VA in most, however, the size of the pinhole played a minor role. Low illumination did have a drastic effect on our results not only by decreasing the amount of lenses used for near that gave more positive results, but also when the pinhole was placed in front of the subjects. According to Borish, the pinhole does improve VA by a straight forward process of elimination produced by spherical aberrations of the eye. However, this did not seem to be the case in this study under conditions of low illumination. Conclusion:The pinhole effect offers improvement in VA at near by reducing the amount of blur presented to the retina. This study showed that all subjects had an improvement in VA of at least two lines in high illumination. Pinhole size did not alter the results sufficiently thus suggesting that a pinhole, no matter the size, should increase the VA. However this was not the case when illumination was decreased.

Results of the Pinhole Test Correlate with Hybrid Contact Lens Visual Acuity in Patients with Visual Impairment due to Corneal Diseases

“…Pinhole occluders can improve VA by reducing retinal blur presented by narrowing the beam of light entering the eye [31,32], cutting o peripheral aberration [33], and increasing the depth of focus [34,35]. erefore, contact lenses, corneal inlays, and intraocular lenses employing the pinhole principle have been designed and are commercially available [13,36,37].…”

Comparison of Objective and Subjective Changes Induced by Multiple-Pinhole Glasses and Single-Pinhole Glasses

“…A smaller aperture than the pupil can reduce the blur circle (39) and block aberrant incident rays from the peripheral cornea and lens (101112). Hence, pinhole glasses improved distant and near VA.…”

Quantitative Analysis of Functional Changes Caused by Pinhole Glasses

“…Therefore, the entire retinal image becomes sharper. 9,10 In addition, small apertures block aberrant rays emanating from the periphery, [11][12][13] decreasing retinal blur circles. Unfortunately, small aperture size is not without limitations.…”

“…[1][2][3][4] Recently, the insertion of a smallaperture corneal inlay functioning like a pinhole occluder for the correction of presbyopia has heightened interest in pinhole effects. [5][6][7][8] Pinhole occluders may improve vision by reducing blur circle by narrowing the beam of light entering the eye, 9,10 blocking peripheral aberration, [11][12][13] and increasing depth of focus. 14,15 Therefore, pinhole occluders can make images clearer and widen the range of focus.…”