Evidence map›Paper›PMID 39450682›Full record

ArticleOphthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists)2025

Viewing distance, font size and symptoms of eyestrain in non-presbyopic and presbyopic smartphone users.

Shivani Naipal, Nqobile Khumalo, Muhammad Rahmtoola, Sinoxolo Chagi, Luyanda Didi, Sandile Mthethwa, Simmy Ndhlovu, Bhavna Persadh, Nishanee Rampersad

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists), 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

0numbers the graph read from it
0cells of the map it votes in
2citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

2 citing papers in PubMed.

  1. Early-onset Presbyopes: Functional Impact and the Need for Clinical Recognition.Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) · 2026
    Article
  2. Viewing distance, font size and symptoms of eyestrain in non-presbyopic and presbyopic smartphone users.Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) · 2025
    Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

9 authors.

Shivani NaipalDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Nqobile KhumaloDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Muhammad RahmtoolaDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Sinoxolo ChagiDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Luyanda DidiDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Sandile MthethwaDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Simmy NdhlovuDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Bhavna PersadhDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Nishanee RampersadDiscipline of Optometry, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.ORCID 0000-0002-6873-5375

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeSmartphones are the most frequently used digital devices globally with ~6.80 billion users. Despite the ubiquitous use of smartphones, limited information is known on the preferred viewing distance and font size of smartphone users. This study investigated viewing distance, font size and symptoms of eyestrain in non-presbyopic and presbyopic smartphone users.

methodsIn this quantitative research study, viewing distance and font size were measured in a group of non-presbyopes (n = 107) and presbyopes (n = 53), whilst participants viewed a text message and a web page on their own smartphone. Subjects also responded to a verbal questionnaire related to the characteristics of their smartphone and the computer vision syndrome questionnaire to assess symptoms of eyestrain. Data were analysed using descriptive and inferential statistics.

resultsFor the total sample, the mean viewing distance for a text message was 37.13 ± 8.82 cm (median 36.00 cm), and for a web page was 36.11 ± 7.98 cm (median 36.00 cm). Presbyopes had longer median viewing distances compared with non-presbyopes for a text message (41 cm vs. 34 cm, p < 0.001) and web page (40 cm vs. 34 cm, p < 0.001). The font size for non-presbyopes were <1.0 M whilst for presbyopes were >1.2 M. More than twice the percentage of non-presbyopes were classified with digital eyestrain (DES) compared with presbyopes.

conclusionsNon-presbyopes used shorter viewing distances, smaller font sizes and were more predisposed to DES than presbyopes. The viewing distances adopted by presbyopes were similar to the conventional near-working distance of 40 cm. Eye care practitioners should consider viewing distances when assessing near-visual functions and prescribing a near refractive correction, particularly in non-presbyopes. There should be greater awareness of the importance of adopting appropriate viewing distances when using smartphones.

Indexed as

PresbyopiaSmartphoneAdultAgedAsthenopiaFemaleHumansMaleMiddle AgedSurveys and QuestionnairesVisual AcuityYoung Adultdigital devicesfont sizesmartphonessymptoms of eyestrainviewing distance

Identifiers

PMID39450682
PMCPMC11629835

What OpenQuestion holds

Textmetadata
LicenceCC BY-NC-ND
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.