5,557

Comparison of Amplitude of Accommodation in Different Room Illumination while Using VDU as a Target

Chiranjib Majumder, Nur Zafirah Zaimi

Chiranjib Majumder, Twintech International University College of Technology, PersiaranIndustri, Bandar Sri Damansara, 52200 Kuala Lumpur, Malaysia
Nur Zafirah Zaimi, Twintech International University College of Technology, Kuala Lumpur, Malaysia

Conflict-of-interest statement: The author(s) declare(s) that there is no conflict of interest regarding the publication of this paper.

Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http: //creativecommons.org/licenses/by-nc/4.0/

Correspondence to: Chiranjib Majumder, M.Optom, ORBIS fellow in pediatric optometry and Orthoptics, RJN school of Optometry, 18 Vikas Nagar, Near Sai baba Mandir, Kila gate Road, Gwalior-474002, India.
Email: chiranjib1284@gmail.com

Received: May 9, 2017
Revised: September 5, 2017
Accepted: September 6, 2017
Published online: September 18, 2017

ABSTRACT

AIM: To compare the amplitude of accommodation (AA) in different room illumination while using visual display unit (VDU) as a target.

METHOD: A non randomized, cross sectional study includes 32 Malaysians aged between 15 to 35 years despite of races and gender. Convenience sampling method applied. The data analysis carried out by using one way repeated measure ANOVA, to look into the changes in amplitude of accommodation in different illuminations (23 Lux, 17 Lux and 4 Lux).

RESULT: 32 subjects’ data analyzed. Amplitude of accommodation measured via minus-lens method. No significant change noted among three levels of room illumination (p > 0.05) with the mean difference of 0.222DS from the first room illumination to third room illumination. Further, to associate AA among genders, age groups, race and refractive error for different levels of room illumination was not significant (p > 0.05). However, amplitude of accommodation between 15-21years and 22-28 years showed significant (p = 0.047) difference for the first room illumination.

CONCLUSION: The illumination has no clinically significant effect on amplitude of accommodation.

Key words: Amplitude of Accommodation; Room illumination; Visual display unit (VDU); Minus lens method

© 2017 The Author(s). Published by ACT Publishing Group Ltd. All rights reserved.

Majumder C, Zaimi NZ. Comparison of Amplitude of Accommodation in Different Room Illumination while Using VDU as A Target. International Journal of Ophthalmic Research 2017; 3(3): 243-248 Available from: URL: http: //www.ghrnet.org/index.php/ijor/article/view/2070

INTRODUCTION

Since 1972, research into the effects of the VDU on the eye expanded[1]. Due to technological advances, millions of people such as office worker and college students are using computers for prolonged hours. However, after prolonged uses of these visual display units, the symptoms reported were eyestrain, tired eyes, headache, blurred vision, irritation, burning sensation, redness, double vision, neck pain, backache which might caused by combination of individual visual problems, poor workplace conditions and improper work habits[2-3]. On top of that, eye related symptoms reported as the most common health problem among VDT users[4-6].

To measure amplitude of accommodation is one of the necessary part of an eye examination to find out optimal refractive corrections and to reduce the eye related symptoms when doing near work especially while using visual display unit as a target. In addition, accommodation was proven to have association with the symptom of visual fatigue and asthenopia while doing near work. Abnormality associated with accommodation such as accommodative insufficiency, accommodative infacility and lag of accommodation reported among video display terminal (VDU) users in Nepal[7].

Several other studies have shown that visual tasks using visual display unit (VDU) terminals may induce temporary effects in the visual accommodation system[8-9]. However, there are studies which suggest that other causes such as work station lighting and screen quality may induce visual problem of the task[9].

As mentioned above, use of visual display unit not only limited among computer workers, but also among teenagers and youth who use it for entertainment or doing college works. These different groups of people may perform their near work with visual display unit under variable room illumination. Previous study showed that accommodation fatigue causes decrease of visual performance due the variety of room illuminations[10]. However, according to Shahnavaz et al there is no significant correlation between accommodation changes and workstation lighting with the visual fatigue among visual display unit users[11]. So, the aim of this study is to find out any change in amplitude of accommodation occurs or not under different room illuminations, while using the visual display unit as a target.

Material and Methods

Study design and sampling

A cross-sectional study performed with the help of 32 Malaysian subjects, aged 15 to 35 years. The duration of the study period was six months (January 2015 to June 2015) and the study conducted at Twintech Vision Care Center, Malaysia. All the participants need to sign written informed consent before carrying out the study. Permission to conduct the study obtained from the institute and all procedures performed after following the declaration of Helsinki. A convenient sampling technique used.

Inclusion and exclusion

The inclusion criterion of the study was subjects with a best corrected visual acuity of 6/6 and N6. Subjects with any ocular pathology, presbyopia, eye movement disorder, binocular vision anomaly, systemic illness, and contact lens wearers excluded.

Procedure

Detailed history obtained from each subjects followed by measurement of visual acuity, objective and subjective refraction, pupillary evaluation, Near point of accommodation, Near point of convergence, Negative and positive relative accommodation, Negative and Positive fusional vergence for both distance and near, accommodation and vergence facility, Monocular estimation method, cover test, version and duction eye movements, slit lamp examination, and fundus examination. Those who successfully complete early assessments included in the study. “Minus lens method” used to measure amplitude of accommodation under three different room illuminations using VDU as a target. The room attuned with three different levels of room illuminations: 23 Lux (1st), 17 Lux (2nd) and 4 Lux (3rd) based on the availability of illumination in the clinical set up. All measurements done from high to low levels of illumination. Three marks drawn in the illumination adjusting unit and whenever the starting point mark of the rotating knob coincides with those three (fixed) different markings, illumination measured with the help of Lux meter for each marking. A table equipped with a chin rest and an adjacent protector to make a constant viewing distance (33 cm) and viewing angle (30 degrees). A horizontal target of N6 size given on a VDU with a constant brightness (80%) which was same throughout the test. The subject asked to place their chin over the chin rest and the viewing angle of 30 degree adjusted from the outer canthus with the help of a protractor during each measurement to avoid bias. The testing distance fixed and measured with a ruler. All measurements taken from the plane of trial frame. Patients those who wear spectacles, their refractive correction substituted to the trial frame before measuring the amplitude of accommodation. Subjects positioned in a headrest to ensure consistency of eye and head position. The target used was a visual display unit (Apple I-pad 2, with height of 9.50 inches and width of 7.31 inches) with a screen display of 9.7-inch (diagonal) LED-backlit glossy widescreen Multi-Touch display with IPS technology and screen resolution of 1024-by-768-pixel resolution at 132 Pixels Per Inch (PPI). Subjects tested with their best refractive correction. Measurements made on right eyes with left eyes occluded and the order reversed. Throughout the research, target remains at a fixed position (33cm and 30 degree downward gaze). The minus lenses offered in 0.25Ds step and a constant vertex distance of 12mm preserved throughout the research. The subjects asked to inform the first noticeable, continued blur that cannot cleared by conscious effort. The amplitude of accommodation is combining minus lens power introduced plus the 3.00Ds needed to focus initially on the target. The target distance of 33cm maintained rather than 40cm to compensate the minification effect induced by minus lens and reduce the possibility of getting underestimated amplitude of accommodation. In addition, a constant viewing distance and angles can achieved easily by using the minus lens rather than the push-up method.

Statistical Analysis

The Statistical analysis done by using statistical software package Statistical Package for Social Science software (SPSS Inc., Chicago, IL, USA) version 22.0 and Microsoft Office Excel 2007. Shapiro-Wilk test was done to check the normality of the data. The results expressed as mean ± standard deviation if the variable is continuous and as number (percentage) if the categorical, unless otherwise mentioned. To assess the amplitude of accommodation changes among refractive error groups, age groups and three different room illuminations, one way repeated measure ANOVA performed. Post hoc analysis also performed to find out the potential differences within the groups. To evaluate the changes in amplitude of accommodation for gender and race, T-test performed. A p value of less than 0.05 considered significant.

RESULTS

This study had 32 subjects; 19 subjects were male (59.4%) and 13 subjects were females (40.6%) which shown in figure 1. All subjects were within an age group of 15 to 35 years. Subjects grouped into two races: Malay (81.3%) and Non Malay (18.7%) as shown in figure 2. Distribution of refractive error showed more or less equal distribution of myopia (34.4%), hypermetropia (32.8%) and emmetropia (32.8%) as shown in figure 3. Table 1 showed no statistically significant difference (p > 0.05) for amplitude of accommodation in different room illumination for gender. Comparison of amplitude of accommodation within three different age groups also showed no statistically significant difference (p > 0.05) as shown in Tables 2 and 3. However, amplitude of accommodation between 15-21years and 22-28 years showed significant (p = 0.047) difference for the first room illumination. Comparison of amplitude of accommodation with race and refractive error showed no statistically significant differences for three different room illuminations as shown in Tables 4 and 5 respectively. Table 6 showed no significant relationship within the refractive error groups for different levels of illumination. Amplitude of accommodation and illumination levels has no significant relationship as shown in Tables 7 and 8.

Figure 1 Showed distribution of gender where 59.4% are male and 40.6% are female.

Figure 2 Showed distribution of race where81.3% is Malay and 18.7% is non-Malay.

Figure 3 Showed distribution of refractive errors where 32.8% is emmetropia, 34.4% is myopia, and 32.8% is hyperopia.

Table 1 Comparison of amplitude of accommodation in different room illumination between genders
Illumination levelGenderMean ± SDp value
1stMale9.5089 ± 2.305810.529
 Female9.1204 ± 2.47685 
2ndMale9.7437 ± 2.565330.459
 Female9.2612 ± 2.52262 
3rdMale9.8321 ± 2.566220.302
 Female9.1935 ± 2.29448 
p< 0.05 is considered significant.

Table 2 Comparison of amplitude of accommodations within three different age groups in three different room illuminations
IlluminationAgeMean ± SDp value
1st15-219.7046 ± 2.564850.049
22-289.0513 ± 0.58068
29-357.5300 ± 1.04369
2nd15-219.8904 ± 2.780310.067
22-289.3838 ± 0.54809
29-357.6550 ± 0.94491
3rd15-21 9.8354 ± 2.718790.123
22-28 9.6550 ± 0.42258
29-357.9138 ± 1.03695
p< 0.05 is considered significant.

Table 3 Post hoc test showed no significant difference within age groups for levels of illumination
Dependent Variable(I) Age of participant(J) Age of participantMean Difference (I-J)Std. ErrorSig.95% Confidence Interval
Lower BoundUpper Bound
AA in 1st illumination15-2122-280.653330.873531-1.49712.8038
29-352.17458*0.873530.0470.02414.325
22-2815-21-0.653330.873531-2.80381.4971
29-351.521251.143710.565-1.29434.3368
29-3515-21-2.17458*0.873530.047-4.325-0.0241
22-28-1.521251.143710.565-4.33681.2943
AA in 2nd illumination15-2122-280.506670.942631-1.81392.8272
29-352.235420.942630.063-0.08514.556
22-2815-21-0.506670.942631-2.82721.8139
29-351.728751.234190.499-1.30964.7671
29-3515-21-2.235420.942630.063-4.5560.0851
22-28-1.728751.234190.499-4.76711.3096
AA in 3rd illumination15-2122-280.180420.922791-2.09132.4521
29-351.921670.922790.125-0.35014.1934
22-2815-21-0.180420.922791-2.45212.0913
29-351.741251.208220.464-1.23314.7156
29-3515-21-1.921670.922790.125-4.19340.3501
22-28-1.741251.208220.464-4.71561.2331
*. The mean difference is significant at the 0.05 level.

Table 4 Comparison of amplitude of accommodation with race in three different room illuminations
Illumination levelRace of participantMean ± SDp value
1stMalay9.3210 ± 2.490920.799
 Non-malay9.4817 ± 1.80223
2ndMalay9.5165 ± 2.698640.796
 Non-malay9.6825 ± 1.77085
3rdMalay9.4671 ± 2.595660.379
 Non-malay 10.0300 ± 1.78058
p< 0.05 is considered significant.

Table 5 Comparison of amplitude of accommodation with refractive errors in three different room illuminations.
Illumination levelRefractive errorMean ± SDp value
1stEmmetrope10.2200 ± 1.50870 
8.9336 ± 2.935720.121
8.9195 ± 2.26174 
2ndEmmetrope10.4071 ± 1.75534 
9.2500 ± 2.904520.159
9.0000 ± 2.67987 
3rdEmmetrope10.6414 ± 1.83415 
9.0941 ± 2.579290.05
9.0052 ± 2.63437 
p< 0.05 is considered significant.

Table 6 Post hoc test showed no significant difference within refractive errors for levels of illuminations.
Dependent Variable

(I) Refractive error

of participant

(J) Refractive error

of participant

Mean Difference

(I-J)

Std. ErrorSig.95% Confidence Interval
Lower BoundUpper Bound
AA in 1st illuminationemmetropemyope1.286360.708320.223-0.45743.0301
hyperope1.300480.716510.223-0.46343.0644
myopeemmetrope-1.286360.708320.223-3.03010.4574
hyperope0.014110.708321-1.72961.7578
hyperopeemmetrope-1.300480.716510.223-3.06440.4634
myope-0.014110.708321-1.75781.7296
AA in 2nd illuminationemmetropemyope1.157140.763870.405-0.72333.0376
hyperope1.407140.77270.221-0.49513.3094
myopeemmetrope-1.157140.763870.405-3.03760.7233
hyperope0.250.763871-1.63052.1305
hyperopeemmetrope-1.407140.77270.221-3.30940.4951
myope-0.250.763871-2.13051.6305
AA in 3rd illuminationemmetropehyperope1.636190.734760.089-0.17263.445
myope-1.547340.726360.112-3.33550.2408
myopehyperope0.088850.726361-1.69931.877
emmetrope-1.547340.726360.1120.2408-3.3355
hyperopemyope-0.088850.726361-1.8771.6993
emmetrope1.636190.734760.0893.445-0.1726
*. The mean difference is significant at the 0.05 level.

Table 7 Comparison of Amplitude of Accommodation in three different room illuminations.
Illumination levelAmplitude of Accommodation (D) Mean ± SDp value
1st9.3511 ± 2.36516 
2nd9.5477 ± 2.539150.118
3rd9.5727 ± 2.46105 
p< 0.05 is considered significant.

Table 8 Post hoc test showed no significant difference within Amplitude of Accommodation for levels of illumination.
Pairwise Comparisons
(I) AA(J) AAMean Difference (I-J)Std. ErrorSig.a95% Confidence Interval for Differencea
Lower BoundUpper Bound
1st2nd-0.1970.0990.158-0.4410.048
 3rd-0.2220.140.352-0.5650.122
2nd1st0.1970.0990.158-0.0480.441
 3rd-0.0250.0961-0.2610.211
3rd1st0.2220.140.352-0.1220.565
 2nd0.0250.0961-0.2110.261
p< 0.05 is considered significant.

DISCUSSION

The objective of this study is to find out the relation between amplitude of accommodation and room illumination. This study also tried to prove another interesting relationship between gender, age, race and refractive error with amplitude of accommodation at three different room illuminations. No statistically significant difference in amplitude of accommodation between gender for three different room illuminations (p > 0.05) noted. Our study finding supported by Yavas et al’s study (p = 0.54) although both the study uses different techniques to measure amplitude of accommodation (i.e. minus lens technique and infra-red photorefractor technique respectively)[12]. However, this study noted the difference of amplitude of accommodation for three different room illuminations at 30° downward gaze in compare to Yavas et al’s study where they have viewed the difference of amplitude of accommodation at primary gaze[12]. There is no previous study which can contradict or support our study for amplitude of accommodation at three different illumination level and gender.

When amplitude of accommodation for three age groups (15-21, 22-28, 29-35 years) compared, no statistically significant difference in amplitude of accommodation found among three groups for second room illumination (p = 0.067) and third room illumination (p = 0.123), but a significant difference noted for the first room illumination (p = 0.049). This study results contradict Atchison et al’s result where they found a significant relation between age group and eye gaze direction for both nearpoint and amplitude (p < 0.05) but not for far point (p = 0.31)[13]. The age group of 15-35 recruited for our study because normal amplitude of accommodation need to be measured. Unequal distribution of subjects is the reason why we did not find any significant difference between the amplitude of accommodation for second and third room illuminations and age group compared to Atchison et al’s study[13]. In this study most of our subjects fall under the age group of 15-21 years. Further, Atchison et al study measures amplitude of accommodation in different eye gaze done by using push-up method whereas minus lens technique used for this study for three illumination, which could be the possible reasons for the discrepancy between our findings and Atchison et al’s study findings.13 Besides, we didn’t find any study that either agree or contradict our results about the significant interaction between the room illumination and the age groups.

This study didn’t show any significant difference in the amplitude of accommodation among race for three different room illumination ( first room illumination p = 0.799, second room illumination p = 0.796 and third room illumination p = 0.379). This study finding for the amplitude of accommodation among race contradicts Edwards et al’s study,where the effect of race has reported to influence the amplitude of accommodation. Caucasion subjects having higher amplitude of accommodation than Chinese subjects[14]. The possible difference between our study and Edwards et al’s st is because of the method and ethinicity difference. This study used minus lens technique whereas Edward et al used push up technique to measure ampitude of accommodation. Moreover, in this study majority of the subjects were Malay in compare to Edward et al’s study where chinese predominance was more. This study didn’t show any statistically significant difference in the amplitude of accommodation among different refractive error groups for three different room illuminations (first room illumination p = 0.121,second room illumination p = 0.159 and third room illumination p = 0.050)[14]. However, there is no previous study is there to support or contradict our results in a sense to prove a significant interaction between refractive error and amplitude of accommodation for three different room illumination.

Although the main purpose of this study is to find out the relationship between amplitude of accommodation and different room illumination. There is no statistically significant relationship exists between amplitude of accommodation and different room illumination (p = 0.118). Furthermore, we have established that amplitude of accommodation increases from the first room illumination to the third room illumination with the mean difference of 0.222DS. This study finding contradicts Gur et al’s finding where amplitude of accommodation decreased of 0.69DS among the VDU workers, before and after work examination with significance value of (p < 0.0001)[15]. Due to the method difference a large discrepancy exists between the two study result. This study used minus lens technique whereas Gur et al’s study used push-up method with non-illuminated target to measure the amplitude of accommodation. Besides that, measurement of AA done under three different room illuminations for this study but Gur et al study was performed under fixed room illumination[15]. In another study by M Shivaram et al also showed no significant difference in NPA (p = 0.43) with different spectral distribution of light which supports our study findings[16].

Conclusion

Changing the level of room illumination has no significant effect on amplitude of accommodation, although amplitude of accommodation (AA) increased with a decrease of room illumination. In addition to that age group, gender, race and refractive error also showed no significant effect on amplitude of accommodation for three different room illuminations except age group for the first room illumination.

Acknowledgements

I would like to thank all my colleagues for their valuable guidance and advice throughout the research. I am grateful to our Dean and Vice chancellor of our university for giving me the opportunity to conduct this research. Special thanks to all my subjects who had participated to make this research complete.

REFERENCES

1. Matula R A. Effects of visual display units on the eyes: A bibliography (1972- 1980). Human Factors 1981; 23: 581-586; [PMID: 7033106]; [DOI: 10.1177/001872088102300507]

2. Cole BL, Maddocks JD, Sharpe K. Effect of VDUs on the eyes- report of a six-year epidemiological study. Optom Vis Sci 1996; 73: 512-528; [PMID: 8869982]

3. Collins MJ, Brown B, Bowman KJ, Carkeet A. Symptoms associated with VDT use. Clin Exp optometry 1990; 73: 111-118; [DOI: 10.1111/j.1444-0938.1990.tb03864.x]

4. Sheedy JE. Vision problems at video display terminals: A survey of optometrists. J Am Optom Assoc 1992; 63: 687-692; [PMID: 1430742]

5. Costanza MA. Visual and ocular symptoms related to the use of video display terminals. J Behav Optom. 1994; 5: 31-36

6. Thomson WD. Eye problems and visual display terminals – the facts anad fallacies. Ophthalmic Physiol Opt. 1998; 18: 111-119; [PMID: 9692030]

7. Shrestha GS, Mohamed FN, Shah DN. Visual problems among video display terminal (VDT) users in Nepal. J Optom. 2011; 4(2):56-62; [PMCID: PMC3974381]; [DOI: 10.1016/S1888-4296(11)70042-5]

8. Holler H, Kundi M, Schmid H, Stidl H G, Thaler A, Winter N. Arbeitsbeanspruchung und Augenbelastung an Bildschirmgeraten. Ed. Automationsausschuss des Gewerkschaftsbundes. Altmannsdorfer Strasse 154, A-1232 Wien. 1975.

9. Laubli T, Hunting W, Grandjean E. Visual impairments in VDU operators related to environmental conditions. Ergonomic aspects of visual display terminals. 1980 Mar: 85-94.

10. Simonson E, Brozek J. Effects of illumination level on visual performance and fatigue. JOSA. 1948 Apr 1; 38(4): 384-397. [PMID: 18913499]

11. Shahnavaz H & Hedman L. Visual Accommodation Changes In Vdu-Operators Related To Environmental Lighting And Screen Quality. Ergonomics 1984; 27:10, 1071-82; [PMID: 6510407]; [DOI: 10.1080/00140138408963586]

12. Yavas G.F, Ozturk F, Kusbeci T, Inan UU, Kaplan U, Ermis SS. (23 May 2008). Evaluation of the change in accommodation amplitude in subjects with pseudoexfoliation. Eye. 2009; 23: 822-26; [PMID: 18497833]; [DOI: 10.1038/eye.2008.143]

13. Atchison DA, Claydon CA, Irwin SE. Amplitude of accommodation for different head positions and different directions of eye gaze. Optom Vis Sci. 1994; 71: 339-45; [PMID: 8065710]

14. Edwards MH, Law LF, Lee CM, Leung KM. & Lui WO. Clinical norms for amplitude of accommodation in Chinese. Opthal Physiol Opt 1993; 13: 199-204; [PMID:8265157]

15. Gur S, Ron S and Heicklen-Klein A. Objective evaluation of visual fatigue in VDU workers. Occup. Med. 1994; 44: 201-04; [PMID: 7949062]

16. Male SR, Bhardwaj R, Majumder C. Influence of spectral distribution on accommodation—vergence and reading performance. Ann Eye Sci 2017; 2: 29; [DOI: 10.21037/aes.2017.06.01]

Peer reviewer: Male Shiva Ram

Refbacks

  • There are currently no refbacks.

Comments on this article

View all comments