Clinical and Epidemiologic Research Quantitative Analysis of Functional Changes Caused by Pinhole Glasses Won Soo Kim,1 In Ki Park,2 and Yeoun Sook Chun1 1Department of Ophthalmology, Chung-Ang University College of Medicine, Chung-Ang University Hospital, Seoul, Korea 2Department of Ophthalmology, KyungHee University College of Medicine, KyungHee Medical Center, Seoul, Korea Correspondence: Yeoun Sook Chun, PURPOSE. To quantify the visual functional changes caused by pinhole glasses. Department of Ophthalmology, Chung-Ang University College of METHODS. Healthy subjects underwent ophthalmic examinations including uncorrected distance Medicine, Chung-Ang University visual acuity (UDVA) and corrected near visual acuity (CNVA), pupil size, depth of focus (DOF), Hospital, 102 Heukseok-ro, Dongjak- accommodative amplitude, visual field (VF) test, contrast sensitivity (CS), and stereopsis. gu, Seoul 156-755, Korea; Subjects underwent the same examinations while wearing pinhole glasses 1 week later. [email protected]. RESULTS. Forty-eight eyes of 48 subjects (24 male and 24 female) with a mean age of 35.5 6 6.7 Submitted: May 15, 2014 years and a mean spherical equivalent of À2.4 6 3.3 diopters (D) were enrolled. The pinhole Accepted: July 31, 2014 glasses significantly improved UDVA and CNVA (logMAR) from 0.44 6 0.46 and 0.26 6 0.40 Citation: Kim WS, Park IK, Chun YS. to 0.19 6 0.25 and 0.14 6 0.22, respectively. The pinhole glasses markedly enlarged pupils Quantitative analysis of functional from 3.6 6 0.5 mm photopic size to 6.0 6 0.5 mm, very close to the mesopic size of 6.2 6 changes caused by pinhole glasses. 0.6 mm. Mean DOF and accommodative amplitude also significantly increased by Invest Ophthalmol Vis Sci. approximately 50%, while VF featured a general reduction of sensitivity. Mean deviation 2014;55:6679–6685. DOI:10.1167/ (MD) significantly decreased from À0.48 6 1.57 to À4.22 6 1.66 dB, and visual field index iovs.14-14801 (VFI) decreased from 99.4 6 0.7% to 98.4 6 1.3%. The CS decreased significantly at all four spatial frequencies, and stereopsis deteriorated with pinhole glasses. CONCLUSIONS. The pinhole glasses improved visual acuity, DOF, and accommodative amplitude; however, they resulted in decreased visual quality including general reduction of VF sensitivity, CS, and stereopsis. Therefore, particular attention is needed when wearing pinhole glasses while driving, playing sports, or working with instruments. (ClinicalTrials.gov number, NCT02111356.) Keywords: accommodative amplitude, functional changes, pinhole glasses, visual acuity, visual field test he single pinhole occluder is a simple device used by Advertisements have suggested that these types of pinhole T ophthalmologists and optometrists for diagnosis of refrac- glasses help exercise and relax eye muscles. However, there is tive errors. Due to its easy handling and short examination no scientific evidence that continuously wearing these glasses time, it has been widely used for rapid screening of visual acuity will result in permanent correction of ametropia and presby- impairment and measurement of visual acuity in large-scale opia. Furthermore, there are few clinical studies regarding epidemiological studies.1–4 Recently, the insertion of a small- visual functional changes with pinhole glasses. aperture corneal inlay functioning like a pinhole occluder for Accordingly, the purpose of this study was to evaluate the influence of pinhole glasses on visual function as measured by the correction of presbyopia has heightened interest in pinhole visual acuity, pupil size, depth of focus, accommodative effects.5–8 amplitude, visual field, contrast sensitivity, and stereopsis. Pinhole occluders may improve vision by reducing blur circle by narrowing the beam of light entering the eye,9,10 11–13 blocking peripheral aberration, and increasing depth of METHODS focus.14,15 Therefore, pinhole occluders can make images clearer and widen the range of focus. However, they can also This study was approved by the Chung-Ang University Hospital induce reduction of the amount of light reaching the retina,9 Institutional Review Board and adhered to the tenets of the diffraction blurring,16,17 and visual field restriction.16 Declaration of Helsinki. Informed consent was obtained from all participants. Clinical trial registration was done at www. Given these problems, pinhole glasses with a series of ClinicalTrials.gov (Identifier: NCT02111356). We recruited multiple, equally sized, regularly placed pinholes have some subjects who visited our clinic for ocular examination. Subjects advantages. Multiple pinholes make it easier to find a hole were included if they were between 20 and 50 years of age and centered on the pupils. They can increase the incident light had spherical equivalents within 66.0 diopters (D), correctable rays to improve brightness and may improve visual field distance and near visual acuity by glasses up to 20/20, normal restriction. On the other hand, multiple pinholes can disturb intraocular pressure, optic discs with a healthy appearance, and images owing to multiple images and eyestrain due to normal ocular alignment. Subjects were excluded if they had afterimage of the rim of each hole. disturbance of accommodation due to an Adie’s pupil or Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc. www.iovs.org j ISSN: 1552-5783 6679 Downloaded from iovs.arvojournals.org on 10/01/2021 Quantitative Analysis of Functional Changes Caused by Pinhole Glasses IOVS j October 2014 j Vol. 55 j No. 10 j 6680 FIGURE 1. (A) Pinhole glasses with 125 pinholes in each glass lens. The pinholes with a 0.9-mm aperture were separated by 3 mm horizontally and vertically and 3.5 mm diagonally. (B) Pupil size while wearing the pinhole glasses was checked by the ruler attached to the lateral rim of the glasses. Parkinson’s disease, previous ocular surgery, a history of ocular À3.0 to þ3.0 D in 0.5-D increments in a randomized order. The trauma, a history of systemic or topical medication that might range of added lenses that maintained visual acuity of 20/25 or affect accommodation, corneal pathologic features, glaucoma- better during defocus was recorded. For example, if a subject tous optic disc, glaucoma, cataracts of grade II or greater by the could read 20/25 or better with an added lens from À1.5 to Lens Opacities Classification System III (LOCS III),18 vitreous þ1.0 D, his or her DOF was 2.5 D.19 opacity, or retinal abnormalities that might limit the accuracy The monocular near point of accommodation (NPA) was of testing. obtained using Donder’s push-up method.20 The subject was All healthy participants underwent ophthalmic examination instructed to view the target letter (20/20 reduced Snellen including manifest refraction, uncorrected distance visual number), which initially was positioned at approximately 40 acuity (UDVA), uncorrected near visual acuity (UNVA), correct- cm. The target then was moved progressively closer to the ed distance visual acuity (CDVA), corrected near visual acuity patient’s eye at approximately 5 cm/s until the subject noticed (CNVA), pupil size, depth of focus (DOF), accommodative the target starting to blur. The distance between the point of amplitude, standard automated perimetry, contrast sensitivity blurring and the spectacle plane in meters was measured, and (CS), and stereopsis. Subjects underwent the same examina- the inverse of the distance was calculated as diopters. tions while wearing pinhole glasses 1 week later. Although both Measured accommodative amplitude while wearing pinhole eyes of subjects were examined, only right eye data were glasses was a combination of pseudoaccommodation induced included in the analysis for all measurements except stereopsis. by pinhole glasses and real accommodation. Real accommoda- Applied pinhole glasses (Trayner Pinhole Glasses; Trayner tion was included in both conditions, with and without Glasses, Ivybridge Devon, UK) had two 5.2- 3 4.5-cm opaque pinhole glasses. Therefore, the difference between accommo- black plastic discs of 1.7-mm thickness with 125 pinholes in dative amplitude with and without pinhole glasses represents each glass lens. The pinholes are lined up in 11 parallel the pseudoaccommodative power induced by pinhole glasses. horizontal rows, with each row displaced laterally by one-half We defined this pseudoaccommodative power as an accom- spacing between holes. Pinholes had a 0.9-mm aperture and modative amplitude pinhole (AApinhole). were separated by 3 mm horizontally and vertically and 3.5 mm Visual field (VF) test was performed with a Humphrey diagonally (Fig. 1). Visual Field Analyzer (Carl Zeiss Meditec, Inc., Dublin, CA, USA) using the 30–2 Swedish interactive threshold algorithm. Ophthalmic Examination Test time, visual field index (VFI), mean deviation (MD), and pattern standard deviation (PSD) were recorded. Uncorrected distance visual acuity, CDVA, and distance visual The monocular CS test was performed using a CSV-1000E acuity with the pinhole glasses (PinholeDVA) were measured Contrast Testing Instrument (VectorVision, Dayton, OH, USA) using Snellen chart (Precision Vision, La Salle, IL, USA) at 4 m. at 2.5-m distance under standard brightness (85 cd/m2). This Uncorrected near visual acuity, CNVA, and near visual acuity test was composed of the following four spatial frequencies: A with the pinhole glasses (PinholeNVA) were measured using (3 cycles per degree [cyc/deg]), B (6 cyc/deg), C (12 cyc/deg), Logarithmic Visual Acuity Chart 2000 (Precision Vision) at 40 and D (18 cyc/deg). The result was converted to a log scale. cm. Visual acuity was converted to a logarithm of the minimal For the measurement of stereopsis, the Randot Stereotest angle of resolution score (logMAR). (Stereo Optical Co., Chicago, IL, USA) was used. This test was Pupil size was measured using a WASCA Analyzer (Carl Zeiss performed at 40 cm with the subject wearing the polarizing Meditec, Oberkochen, Germany) at photopic and mesopic spectacles. The booklet was held at 40 cm perpendicular to the conditions (85 and 5 cd/m2, respectively).