Font Size and Viewing Distance of Handheld Smart Phones

State University of New York, SUNY State College of Optometry, New York, New York 10036, USA.
Optometry and vision science: official publication of the American Academy of Optometry (Impact Factor: 1.6). 04/2011; 88(7):795-7. DOI: 10.1097/OPX.0b013e3182198792
Source: PubMed


The use of handheld smart phones for written communication is becoming ubiquitous in modern society. The relatively small screens found in these devices may necessitate close working distances and small text sizes, which can increase the demands placed on accommodation and vergence.
Font size and viewing distance were measured while subjects used handheld electronic devices in two separate trials. In the first study (n=129), subjects were asked to show a typical text message on their own personal phone and to hold the device "as if they were about to read a text message." A second trial was conducted in a similar manner except subjects (n=100) were asked to view a specific web page from the internet.
For text messages and internet viewing, the mean font size was 1.1 M (range, 0.7 to 2.1 M) and 0.8 M (range, 0.3 to 1.4 M), respectively. The mean working distance for text messages and internet viewing was 36.2 cm (range, 17.5 to 58.0 cm) and 32.2 cm (range, 19 to 60 cm), respectively.
The mean font size for both conditions was comparable with newspaper print, although some subjects viewed text that was considerably smaller. However, the mean working distances were closer than the typical near working distance of 40 cm for adults when viewing hardcopy text. These close distances place increased demands on both accommodation and vergence, which could exacerbate symptoms. Practitioners need to consider the closer distances adopted while viewing material on smart phones when examining patients and prescribing refractive corrections for use at near, as well as when treating patients presenting with asthenopia associated with nearwork.

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    • "Furthermore, spinal structures are connected to one another and deformation of the cervical position can affect the lumbar vertebrae negatively8). Neck flexion is expected to increase due to the frequent use of the relatively small screen of a smartphone compared to that of a desktop computer9). One study reported that the long and continuous use of a smartphone not only incurred pain in the neck and waist but also impaired proprioception10). "
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    ABSTRACT: [Purpose] The purpose of this study was to compare cervical repositioning errors according to smartphone addiction grades of adults in their 20s. [Subjects and Methods] A survey of smartphone addiction was conducted of 200 adults. Based on the survey results, 30 subjects were chosen to participate in this study, and they were divided into three groups of 10; a Normal Group, a Moderate Addiction Group, and a Severe Addiction Group. After attaching a C-ROM, we measured the cervical repositioning errors of flexion, extension, right lateral flexion and left lateral flexion. [Results] Significant differences in the cervical repositioning errors of flexion, extension, and right and left lateral flexion were found among the Normal Group, Moderate Addiction Group, and Severe Addiction Group. In particular, the Severe Addiction Group showed the largest errors. [Conclusion] The result indicates that as smartphone addiction becomes more severe, a person is more likely to show impaired proprioception, as well as impaired ability to recognize the right posture. Thus, musculoskeletal problems due to smartphone addiction should be resolved through social cognition and intervention, and physical therapeutic education and intervention to educate people about correct postures.
    Journal of Physical Therapy Science 04/2014; 26(4):595-8. DOI:10.1589/jpts.26.595 · 0.39 Impact Factor
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    • "To reduce this ambiguity, we consider the usage of cameras as a source of detection information. Our approach is based on recent statistics that show that a smart phone user holds the smart phone at 12.5 inches from her eyes while surfing and at 14.1 inches away from her eyes while texting [3]. At these distances, if the smart phone user is watching the TV, the TV will either partially or fully appear within the camera's frame. "
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    ABSTRACT: Recent studies show that the TV viewing experience is changing giving the rise of trends like "multi-screen viewing" and "connected viewers". These trends describe TV viewers that use mobile devices (e.g. tablets and smart phones) while watching TV. In this paper, we exploit the context information available from the ubiquitous mobile devices to detect the presence of TVs and track the media being viewed. Our approach leverages the array of sensors available in modern mobile devices, e.g. cameras and microphones, to detect the location of TV sets, their state (ON or OFF), and the channels they are currently tuned to. We present the feasibility of the proposed sensing technique using our implementation on Android phones with different realistic scenarios. Our results show that in a controlled environment a detection accuracy of 0.978 F-measure could be achieved.
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    • "이렇듯 척추 구조물은 서로 사슬 (chain)과 같이 연결되어 목뼈 자세의 변형은 허리뼈 자세까지 영향을 미칠 수 있다(Page 등, 2009). 이전 연 구에서는 영상단말기 사용시간이 길어질수록 목과 체간 의 굽힘은 더욱 증가된다고 보고하였으며(Lee 등, 2011), 스마트폰과 같은 영상단말기는 일반적인 컴퓨터 에 비해 상대적으로 작은 화면 때문에 목 굽힘이 더욱 증가될 것이라고 하였다(Bababekova 등, 2011; Szeto 등, 2002 "
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    ABSTRACT: The purpose of this study was to assess the influence of the duration of smartphone usage on cervical and lumbar spine flexion angles and reposition error in the cervical spine. The study included 18 healthy smartphone users (7 males and 11 females). We measured the kinematics of the upper and lower cervical and lumbar spine flexion angles and the reposition error of the upper and lower cervical spine after 3 s and 300 s smartphone use in sitting. A paired t-test was used to compare the effects of the duration of smartphone usage on the kinematics of cervical and lumbar spine flexion angles and reposition error. The flexion angles of the lower cervical and lumbar spine and the reposition error in the upper and lower cervical spine were significantly increased after 300 s smartphone of use (p.05). These findings suggest that prolonged use of smartphones can induce changes in cervical and lumbar spine posture and proprioception in the cervical spine.
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