Quantitative Analysis of Functional Changes Caused by Pinhole Glasses

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 2.4 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 0.48 6 1.57 to 4.22 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

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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 3.0 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 1.5 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). In addition, pupil subject’s visual axis, especially while wearing pinhole glasses. size while wearing pinhole glasses under photopic conditions Subjects were asked to identify the one circle that popped out was measured with the ruler attached to the lateral rim of the of the page in each set. Threshold of stereopsis was recorded glasses (Fig. 1). Pinhole pupil size was measured indirectly in seconds of arc. from the side; therefore, the measurement was inevitably approximate. Statistical Analysis The monocular DOF was measured with a 4-m logMAR Snellen chart under distance correction without cycloplegics. Paired t-test was used to compare the differences between Spherical defocus was induced by adding spherical lenses from wearing and not wearing the pinhole glasses in all exams.

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TABLE 1. Clinical and Demographic Characteristics of the Subjects

Characteristic Value

Number of subjects 48 Male:female 24:24 Mean age, y (range) 35.5 6 6.7 (27–44) Mean spherical equivalent, D (range) 2.4 6 3.3 (6.0 to þ2.0) Mean UDVA/UNVA, logMAR 0.44 6 0.46/0.26 6 0.40 Mean CDVA/CNVA, logMAR 0.00 6 0.00/0.00 6 0.00 Mean PinholeDVA/PinoleNVA, logMAR 0.19 6 0.25/0.14 6 0.22 Mean pupil size, mm (range) Photopic 3.6 6 0.5 (3.1–4.8) Mesopic 6.2 6 0.6 (5.3–7.2) Pinhole glasses 6.0 6 0.5 (5.0–6.5) Values are expressed as mean 6 standard deviation.

FIGURE 2. Bar graph showing the effects of pinhole glasses on distance Correlation between pupil size and visual acuity change was and near visual acuity. PinholeDVA and PinholeNVA were better than evaluated using Pearson correlation test. Statistical analyses UDVA and UNVA, respectively (paired t-test, P < 0.001 and P ¼ 0.002, were performed using SPSS software (ver. 19.0 for Windows; respectively). UDVA, uncorrected distance visual acuity; PinholeDVA, SPSS, Inc., Chicago, IL, USA). Statistical signiﬁcance was distance visual acuity with pinhole glasses; UNVA, uncorrected near visual acuity; PinholeNVA, near visual acuity with pinhole glasses. accepted for P values < 0.05.

RESULTS was 3.56 D (from 9.56 6 2.04 to 13.12 6 2.89 D). The older group contained 16 subjects with a mean age of 43.5 6 0.5 Table 1 shows the characteristics of the 48 eligible subjects. years, and the mean AApinhole was 4.72 D (from 6.24 6 1.83 Thirty-four of 48 subjects (71%) had myopia, 8 (17%) had to 10.96 6 3.49 D). There was no significant difference emmetropia, and only 6 (12%) had hyperopia. All subjects had between the two groups (3.56 vs. 4.72 D, respectively, P ¼ 20/20 CDVA and CNVA. Mean pupil size with pinhole glasses 0.063, Mann-Whitney U test). under photopic conditions was considerably enlarged compared with photopic pupil size (6.0 vs. 3.5 mm, P < 0.001). Furthermore, pinhole pupil size was very close to the mesopic Visual Field pupil size (6.2 mm); the difference between the two values Visual field constriction within the central 308 was not seen in was not statistically significant. any subject. Mean VF test time was prolonged with the pinhole glasses from 359 6 34 to 420 6 30 s (P < 0.001). Mean VFI, Visual Acuity MD, and PSD while wearing pinhole glasses also changed Mean UDVA and PinholeDVA were 0.44 6 0.46 and 0.19 6 significantly. Among these values, the MD value showed the 0.25, respectively. Distance visual acuity improved significantly largest change (decreased by 783%), and VFI showed the while wearing pinhole glasses (P < 0.001). Visual acuity of all smallest change (decreased by 1%). All subjects showed similar subjects with pinhole glasses was better or the same when patterns of VF change; test time increased, MD values compared to that without pinhole glasses. Visual acuity of 12 decreased, PSD values increased, and VFI values changed subjects did not show any change. Ten of these had spherical minimally (Table 2). Therefore, VF while wearing pinhole equivalents in the 0.50 to þ0.50 D range, and their UDVA was glasses featured a generally reduced sensitivity. It was more 20/20. prominent in the peripheral fields than in the central field (Fig. Mean UNVA and PinholeNVA were 0.26 6 0.40 and 0.14 6 4). 0.22, respectively. Near visual acuity improved significantly while wearing pinhole glasses (P ¼ 0.002). No subject had decreased near visual acuity with pinhole glasses. Twenty-two subjects with 20/20 UNVA showed no change with pinhole glasses (Table 1; Fig. 2).

Depth of Focus and Accommodative Amplitude Mean DOF with and without the pinhole glasses was 3.90 6 1.68 and 2.60 6 1.66 D, respectively. All subjects showed increased DOF with pinhole glasses, and the average DOF increase was 1.30 D (P < 0.001) (Fig. 3). Mean accommodative amplitude without pinhole glasses was 8.35 6 2.53 D. With pinhole glasses, it increased to 12.34 6 3.26 D (P < 0.001), which is a mean AApinhole in all subjects of 3.99 D. All 48 subjects experienced improvement in NPA while wearing pinhole glasses. Participants were subdivided into two groups according to age: a 20- to 39-year-old (younger) group and a 40- to 50-year- old (older) group. The younger group consisted of 32 subjects FIGURE 3. Bar graph showing signiﬁcantly improved depth of focus with a mean age of 30.4 6 2.8 years, and the mean AApinhole and accommodative amplitude while wearing pinhole glasses.

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TABLE 2. Change of Parameters of Visual Field Tests Before and After Correlation Between Pupil Size and Visual Acuity Wearing the Pinhole Glasses Change Without With We determined the correlation between pupil size and the Pinhole Pinhole Percentage P difference of distance visual acuity (UDVA PinholeDVA). Glasses Glasses Change* Value† Mesopic pupil size and visual acuity improvement with pinhole Test time, s 359 6 34 420 6 30 þ17 <0.001 glasses showed a significant positive correlation (R ¼ 0.724, P VFI, % 99.4 6 0.7 98.4 6 1.3 1 <0.001 < 0.001). After excluding 10 participants who had 20/20 UDVA MD, dB 0.48 6 1.57 4.22 6 1.66 783 <0.001 at baseline and 20/20 with pinhole glasses, the correlation PSD, dB 1.89 6 1.52 2.26 6 0.71 þ20 0.007 between pupil size and visual acuity change became more positive (R ¼ 0.868, P < 0.001). Pinhole pupil size and visual * þ, increase; , decrease. acuity improvement with pinhole glasses also showed a † P value by paired t-test. significant positive correlation (R ¼ 0.700, P < 0.001), but photopic pupil size did not show any correlation with the Contrast Sensitivity change in distance visual acuity while wearing pinhole glasses (R ¼ 0.211, P ¼ 0.218) (Fig. 6). The decrease of CS was statistically significant at all spatial frequencies (A, B, C, and D) while wearing pinhole glasses (Table 3; Fig. 5). The higher the frequency, the greater the DISCUSSION decrease in CS while wearing pinhole glasses (Table 3). In the current study, we determined the influence of pinhole Stereopsis glasses on eye function. The pinhole glasses improved uncorrected distance and near visual acuity, increased DOF Mean stereopsis with and without pinhole glasses was 44 6 12 and pseudoaccommodative power, and enlarged pupil size; and 90 6 57 seconds of arc, respectively. Therefore, stereopsis however, CS, stereopsis, and VF indicators including MD, PSD, decreased significantly with pinhole glasses (P < 0.001). No VFI, and test time deteriorated. To our knowledge, this is the subject had better stereopsis while wearing pinhole glasses. first report regarding the visual functional changes that occur Only eight of 48 (17%) subjects maintained the same stereopsis while wearing pinhole glasses. values; the other 40 subjects (83%) had deteriorated stereopsis We think that visual acuity with pinhole glasses improved values. due to the original pinhole effects. Small pinhole aperture

FIGURE 4. Visual field tests without (A) and with (B) pinhole glasses. Mean deviation decreased significantly from 0.73 to 4.86 dB, and PSD increased from 1.20 to 2.14 dB. Visual field index changed from 100% to 99%. Abnormalities of retinal sensitivity were observed at the peripheral field area. MD, mean deviation; PSD, pattern standard deviation; VFI, visual field index.

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TABLE 3. Changes of Contrast Sensitivity Before and After Wearing the Pinhole Glasses

Without With Pinhole Pinhole Percentage P Glasses* Glasses* Change† Value‡

A, 3 cyc/deg 1.81 6 0.17 1.60 6 0.22 11.6 0.002 B, 6 cyc/deg 2.10 6 0.15 1.78 6 0.15 15.2 <0.001 C, 12 cyc/deg 1.78 6 0.15 1.30 6 0.19 26.5 <0.001 D, 18 cyc/deg 1.33 6 0.19 0.87 6 0.2 34.6 <0.001 * Values are log scale. † , decrease. ‡ P value by paired t-test.

narrows the envelope of the incident rays, so the size of the retinal blur circle becomes proportionally smaller. Therefore, FIGURE 5. Graph showing decrease of contrast sensitivity at all four the entire retinal image becomes sharper.9,10 In addition, small spatial frequencies while wearing pinhole glasses. cpd, cycles per apertures block aberrant rays emanating from the periph- degree. ery,11–13 decreasing retinal blur circles. Unfortunately, small aperture size is not without limitations. Very small aperture size can induce diffraction and visual acuity decrease. One was the largest. It decreased from 0.48 to 4.22 dB, or 783%. report showed that aperture size smaller than 0.75 mm causes This change is explained by reduced luminance because considerable diffraction blurring, while aperture size larger decrease of MD is similarly shown in central cataract patients. than 2.0 mm causes no diffraction-related problems.16 There- A decibel is 0.1 logarithmic unit, so a change of 3.74 dB fore, it is important to set the appropriate aperture size to represents a 2.4-fold decrease of stimulus attenuation. Howev- simultaneously achieve ideal pinhole effects and avoid er, luminance attenuation was not even for the whole field. diffraction blurring. In this study, we used pinhole glasses Rather, it was more prominent on peripheral fields (Fig. 4). with 0.9-mm pinholes (definitely smaller than the average 3.6- Therefore, mean VFI, which is independent of cataracts and mm photopic pupil), which resulted in improvement of visual puts weight on central field over peripheral fields,25 decreased acuity. by just 1% (Table 2). This result can be explained as follows. Our study demonstrated an increase in DOF (1.30 D) when Rays of light traverse the multiple pinholes from various subjects wore pinhole glasses. There are several factors that directions. The rays pass through cleanly when they are may influence the DOF, including the visual target, luminance, released perpendicularly to the pinhole aperture. However, contrast, spatial frequency, visual acuity, and pupil size. Among when the rays pass through from the periphery, they may slant these, decreased aperture size and decreased luminance from and encounter interference at the aperture or be blocked by wearing pinhole glasses have been shown to result in an the side of the pinhole. The more peripheral the rays, the 21,22 increased DOF. fewer incident rays pass through (Fig. 7). Finally, decreased Pinhole glasses changed accommodative amplitude from sensitivity was more prominent at peripheral fields than at the 8.35 to 12.34 D. That is, the pseudoaccommodative power central field. Although the VF had a generally reduced induced by pinhole glasses was 3.99 D. This effect may be sensitivity with pinhole glasses, VF constriction within the explained by the small aperture of the pinhole glasses central 308 was not shown in any subject. requiring less accommodative power for the same stimulus. Contrast sensitivity while wearing pinhole glasses de- As a result, subjects can generate the maximal amplitude of creased significantly at all four spatial frequencies. The accommodation for a particular stimulus.23 These effects of decrease was more marked with increasing frequency. Similar pinhole glasses can support presbyopia, and this concept led results have been observed in previous studies.6,7 Decrease of to the development of a small-aperture corneal inlay.5–7 luminance was related to deterioration of CS.26,27 Pupil or Image quality increased by a pinhole can be diminished when the level of illumination reaching the retina is pinhole size has a large effect on the optical transfer function 24 of the eye, and if the pupil or pinhole size is fixed, transfer rate attenuated. In this situation, pinhole glasses with a series of 28,29 equally sized, regularly placed pinholes are better than a single decreases more as frequency increases. Accordingly, in our pinhole occluder. Multiple pinholes increase the incident light study, decrease of luminance by pinhole glasses caused general rays and can improve luminance. Nevertheless, the area of the reduction of CS. Since the small aperture of the pinhole played opaque portion of the glasses is still larger than that of the the role of a low-pass filter, decrease of CS was more definite at perforated portion. Therefore, pinhole glasses with 125 high spatial frequency. Stereopsis also decreased with pinhole 0.9-mm pinholes reduce the brightness and enlarge mean glasses. This result is explained by the fact that luminance 30,31 pupil size from 3.6 to 6.0 mm, which is very close to mesopic affects stereopsis and is directly proportionate. pupil size. The impacts of decreased luminance were well Improvement in UDVA while wearing pinhole glasses was demonstrated in test results for VF, CS, and stereopsis. For this markedly related to pupil size. The larger the pinhole pupil size reason, visual quality was markedly decreased if subjects used or mesopic pupil size, the greater the improvement in visual the pinhole glasses under dim illumination, and particular acuity. As mentioned earlier, mean pupil size with pinhole attention is needed when wearing the pinhole glasses under glasses was similar to mesopic pupil size; therefore, mesopic this condition. Considering this aspect, we strictly maintained rather than photopic pupil size might show a positive the room illumination constant during the ocular examina- relationship. We propose the following reasons for this finding. tions. First, a large mesopic pupil size permits a large amount of Visual field index, MD, and PSD of the VF test deteriorated incident rays. Therefore, luminance behind the pinhole glasses with pinhole glasses. Among these changes, the MD change increases. Second, a large pupil reduces diffraction blurring.

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FIGURE 6. Graphs show correlation between pupil size and change of distance visual acuity while wearing pinhole glasses. (A) The larger the mesopic pupil size, the greater the improvement in distance visual acuity (Pearson correlation coefﬁcient, R ¼ 0.724, P < 0.001). (B) Similar correlation was found between pinhole pupil size and the improvement in distance visual acuity (R ¼ 0.700, P < 0.001). (C) Photopic pupil size had no relationship to the change in distance visual acuity (R ¼ 0.211, P ¼ 0.218). Difference in DVA (distance visual acuity) ¼ UDVA (logMAR) distance visual acuity with the pinhole glasses (logMAR).

Third, a large mesopic pupil can include multiple pinholes, no learning effect except for the VF test. Moreover, results making it easier to find a hole centered on the pupil. related to the VF test while wearing pinhole glasses worsened Therefore, the manufacturing features of pinhole glasses despite any learning effect. Therefore, the examination order must be considered in the interpretation of our results. These related to pinhole glasses would not affect the validity of the features include total number of pinholes, size of pinhole results. Another limitation is that objective DOF should be apertures, and separation interval between multiple pinholes. evaluated under the condition of accommodation paralysis Patient characteristics, including vertex distance and the using cycloplegics. However, other studies have shown that the results from DOF studies with and without cycloplegia are mesopic pupil size, should also be considered because if 32 vertex distance increases, awareness of the multiple pinholes similar, and the eye accommodates the minimum amount to place the target within its depth of field to see the object increases. In situations with an enlarged pupil, the eye would clearly, independent of the viewing distance.33 Therefore, it then perceive multiple apertures. can be inferred that evaluation of DOF without cycloplegics Our study has some limitations. All participants underwent would be less affected by accommodation, and thus the results the same ophthalmic examination while wearing pinhole obtained here would be acceptable for measuring DOF. glasses 1 week later. Therefore, some of the differences In conclusion, pinhole glasses have some advantages, between the two conditions could be attributed to the fact including improvement of visual acuity for patients with a that subjects were always tested in the same, rather than UCVA < 20/20, DOF, and amplitude of accommodation; random, order. However, examinations comprised tests with however, they also have disadvantages including general reduction of VF sensitivity, deteriorated contrast sensitivity, and reduction of stereopsis. Therefore, particular attention is needed when wearing the pinhole glasses while driving, playing sports, or working with instruments. Furthermore, pinhole glasses are more beneficial for subjects with larger mesopic pupil size.

Acknowledgments Disclosure: W.S. Kim, None; I.K. Park, None; Y.S. Chun, None

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