Anxiety in Visual Field Testing

Downloaded from http://bjo.bmj.com/ on August 30, 2016 - Published by group.bmj.com Clinical science Anxiety in visual ﬁeld testing Shenton S L Chew, Nathan M Kerr, Aaron B C Wong, Jennifer P Craig, Chi-Ying Chou, Helen V Danesh-Meyer

▸ Additional material is ABSTRACT field reliability. One such potential variable is published online only. To view Background To determine if Humphrey visual field anxiety, which is known to adversely affect general- please visit the journal online 5 (http://dx.doi.org/10.1136/ (HVF) testing induces anxiety and how anxiety relates to ised test performance. bjophthalmol-2015-307110). visual field parameters of reliability and severity. This prospective cohort study was therefore Design A prospective cohort study at a university designed to establish if Humphrey visual field Department of Ophthalmology, fi University of Auckland, af liated private ophthalmic practice. (HVF) testing induces anxiety and whether this Auckland, New Zealand Participants 137 consecutive age-matched and may influence the reliability of the test. In addition, gender-matched patients with glaucoma undergoing the anxiety level induced was compared with that Correspondence to either HVF testing only (n=102) or Heidelberg retinal induced by Heidelberg retinal tomography (HRT) Professor Helen V Danesh- Meyer, Department of tomography (HRT) only (n=35) were enrolled. which requires minimal patient input. Ophthalmology, University of Methods Prior to testing, participants completed the Auckland, Private Bag 92019, State-Trait Anxiety Inventory questionnaire. A 5-point MATERIALS AND METHODS Auckland 1142, New Zealand; Likert scale was used to grade pretest anxiety and was Subjects [email protected] repeated after testing to grade intratest anxiety. Patients attending a glaucoma clinic at a fi Received 18 May 2015 Subjective discomfort parameters were also recorded. university-af liated private ophthalmic practice Revised 21 September 2015 Main outcome measures Anxiety scores were used were invited to participate in the study. The study Accepted 27 October 2015 to make non-parametrical comparisons and correlations adhered to the tenets of the Declaration of Published Online First between cohorts and also against visual field reliability Helsinki. In total, 137 patients provided informed 25 November 2015 and severity indices. consent to participate and participants comprised Results Trait anxiety (p=0.838) and pretest anxiety two cohorts: 102 (49 men, 53 women, mean age (p=0.802) were not significantly different between test ±SD of 62.5±11.9) who underwent anxiety ana- groups. Within the HVF group, intratest anxiety was 1.2 lysis before and immediately after HVF testing and times higher than pretest anxiety (p=0.0001), but was 35 (19 men, 16 women, mean age±SD of 64.1 not significantly different in the HRT group (p=0.145). ±12.3) who underwent an identical analysis before Pretest anxiety was correlated with test unreliability and after HRT testing. None of the participants (Spearman’s r=0.273, p=0.006), which was predictive of had known or treated anxiety disorders. worse test severity (p=0.0027). Subjects who had undergone more than 10 visual field tests had Pretest evaluation significantly lower pretest and intratest anxiety levels All subjects completed a pretest questionnaire com- than those who had not (p=0.0030 and p=0.0004, prising demographic information including age, respectively). gender, duration of follow-up for glaucoma or sus- Conclusions HVF testing induces more anxiety than picion of glaucoma and the number of previous HRT. Increased pretest anxiety may reduce HVF test HVF or HRT tests performed. To confirm parity of reliability. Increased test experience or interventions existing anxiety traits between HVF and HRT aimed at reducing pretest anxiety may result in improved groups, participants underwent an assessment of test reliability and accuracy. their anxiety traits by the State-Trait Anxiety Inventory (STAI) 2 test,6 (see online supplementary appendix 1) a 20-question test to measure ‘trait INTRODUCTION anxiety’ which evaluates a chronic proneness to Glaucoma is primarily a disease of the middle-aged anxiety or a propensity to experience state anxiety and elderly, and the second leading cause of blind- in provocative situations.56The responses to this ness worldwide.12Visual field testing is an integral widely used, validated questionnaire78were component of the clinical assessment of glaucoma recorded on a standard 4-point scale, as ‘almost and is often the basis on which disease progression never’, ‘sometimes’, ‘often’ or ‘almost always’. is monitored and treatment is instigated or modi- Participants then completed a validated assess- fied.1 It is therefore crucial that accurate and reli- ment to measure their pretest ‘state’ anxiety which able results are obtained during visual field testing describes transient feelings of apprehension in in order for patients to receive the most appropri- response to a situation at a given moment in time. ate management. This was recorded on a 5-point Likert scale, However, it has been identified that visual field ranging from ‘not anxious at all’ to ‘extremely testing is a patient’s least preferred clinical test used anxious’9 (see online supplementary appendix 2). in glaucoma management.34Visual field tests require active patient participation and conse- Post-test evaluation fl To cite: Chew SSL, quently may be in uenced by variables that affect Immediately after the clinical testing procedure Kerr NM, Wong ABC, et al. patient attention, concentration or physical ability (either HVF or HRT), the subjects completed an Br J Ophthalmol to perform the tests. Despite this, there is limited identical 5-point Likert scale questionnaire grading – 2016;100:1128 1133. research regarding such variables that affect visual their intratest anxiety (anxiety experienced during

1128 Chew SSL, et al. Br J Ophthalmol 2016;100:1128–1133. doi:10.1136/bjophthalmol-2015-307110 Downloaded from http://bjo.bmj.com/ on August 30, 2016 - Published by group.bmj.com Clinical science the test). Likert scales were selected over the 20 question STAI cooperation and takes approximately 5–7 min per eye, including ‘state anxiety’ questionnaire as it was felt that the significantly set-up and preparation time. Again, the eye that was tested first shorter completion times would result in a more accurate repre- was randomised. sentation of anxiety levels, given the short duration of HVF and HRT testing. Similarly, discrete scoring was used rather than a continuous visual analogue scale to simplify the recording Statistics process for subjects. A biostatistician, using SAS V.9.1.3, evaluated ordinal data non- In addition, five subjective discomfort parameters including parametrically. Spearman’s distribution-free correlation coeffi- how difficult, tiring, long, physically uncomfortable and cient was calculated, and groups compared by Wilcoxon test unpleasant the participant had found the test were also recorded (continuous non-normally distributed data), Student’s t test 2 on 5-point Likert scales (see online supplementary appendix 2). (continuous normally distributed data) or using the χ test for categorical data. Standard multiple linear regression was used to analyse multivariate models. Models were constructed using Test parameters iterative procedures (stepwise, forward and backward selection) One hundred and two participants underwent HVF testing, but encompassing the following variables: age, pretest anxiety, not HRT testing, by standard automated white-on-white perim- average test duration and subjective reporting of tests being diffi- 2 etry on a 10 cd/m background, with a Humphrey Field cult, tiring, long, uncomfortable and unpleasant. These variables Analyzer II (Carl Zeiss Meditec, Dublin, California, USA) using were included based on external clinical judgement and have the SITA 24-2 standard algorithm. Test duration was approxi- been identified by participants as relevant factors in a qualitative mately 5 min per eye. HVF parameters recorded included mean investigation into HVF testing.4 deviation (MD), pattern SD (PSD), fixation losses (FLs), false positives (FPs), false negatives (FNs) and test duration. Visual fields were considered unreliable if FP or FN exceeded 33% or – FL exceeded 20%.10 12 HVF data for right and left eyes was averaged for correlation with anxiety and discomfort scores. The eye that was tested first was randomised. Participants were tested in individual rooms with distractions kept to a minimum. A technician was present with the patient at all times. As a basis for comparison, 35 participants underwent HRT testing (HRT-3, versions 2.01/3.04 HRT; Heidelberg Engineering, Heidelberg, Germany) but not HVF testing. HRT-3 is a confocal scanning laser ophthalmoscope that images the optic nerve head. Image acquisition requires minimal patient

Table 1 Demographics for HVF and HRT groups HVF HRT

Demographic Age (years) 62.7 (27–92) 64.1 (35–86) Gender (M:F) 0.92:1 1.19:1 Duration since diagnosis First visit 8% 20% <2 years 29% 26% 2–5 years 35% 40% >5 years 27% 14% Previous number of tests 0 2% 23% 1 15% 11% 2–5 43% 54% 6–10 22% 11% >10 17% 0% Trait anxiety (out of 80)* 33 (20–60) 33 (22–48) Reliability Average fixation losses (%) 7.7 (0–56.2) – Average false positives (%) 2.8 (0–18.0) – Average false negatives (%) 3.1 (0–34.5) – Severity Mean deviation (dB) −3.4 (−27.6 to 2.1) – Pattern SD (dB) 3.9 (1.2–12.9) – Average test duration (seconds) 329 (249–513) – Values in parentheses represent the range of the demographic. Figure 1 (A) Trait anxiety and pretest anxiety for Humphrey visual *Median values for ordinal and categorical data. ﬁ HRT, Heidelberg retinal tomography; HVP, Humphrey visual field. eld participants, r=0.18, p=0.068. (B) Trait anxiety and pretest anxiety for Heidelberg retinal tomography participants, r=0.28, p=0.101.

Chew SSL, et al. Br J Ophthalmol 2016;100:1128–1133. doi:10.1136/bjophthalmol-2015-307110 1129 Downloaded from http://bjo.bmj.com/ on August 30, 2016 - Published by group.bmj.com Clinical science

RESULTS trend of decreased intratest anxiety compared with pretest Demographics anxiety (p=0.145) (figure 2A, B). Intratest anxiety was found to All subjects (n=137), who consented to participate, completed be correlated with the pretest anxiety, for the HVF and HRT the study. Average age was 62.7 years (SD, 11.9; range, 27–92) groups. (HVF, Spearman’s r=0.654, p<0.0001; HRT, in the HVF group, which was not significantly different from Spearman’s r=0.524, p=0.001). 64.1 years (SD 12.3; range 35–86) in the HRT group (t=0.69, Stratification of the data by gender and duration since diagno- p=0.476). Similarly the ratios of men to women (HVF, 0.92:1; sis did not show any significant difference in trait anxiety, HRT 1.19:1; χ2=0.41, p=0.524) and duration since glaucoma pretest anxiety or intratest anxiety for the HVF and HRT diagnosis of participants (HVF, 2–5 years; HRT, 2–5 years; groups (p>0.05 in all cases). However in the HVF group, strati- χ2=2.57, p=0.13) were not significantly different between the fication by the number of previous tests showed that experience groups undergoing HVF and HRT testing (table 1). of >10 tests was associated with significantly reduced pretest and intratest anxiety (32% reduction, p=0.003; 39% reduction, p<0.001, respectively), but not trait anxiety (Z=−1.793, Anxiety p=0.072) when compared with less experienced participants Trait anxiety, as defined by the STAI score, was not significantly (≤10 tests). The HRT group did not show any significant differ- different between the HVF and HRT groups (p=0.838). Values ences in trait anxiety, pretest anxiety, or intratest anxiety when for both groups were comparable to normative data for age- stratified by number of previous tests (p>0.05 in all cases). matched individuals.6 Trait anxiety did not correlate with Additionally, there was no correlation between age and trait pretest anxiety for either HVF (p=0.068) or HRT (p=0.101), anxiety (HVF, p=0.562; HRT, p=0.282), pretest anxiety (HVF, however the trend (figure 1A, B) was for a positive correlation. p=0.719; HRT, p=0.656) or intratest anxiety (HVF, p=0.575; Trait anxiety did correlate with intratest anxiety for the HVF HRT, p=0.844) for either the HVF or HRT groups. group (Spearman’s r=0.268, p=0.006), but not the HRT group (p=0.494). Other discomfort parameters While there was also no statistically significant difference in The HVF group reported their test experience to be 1.6 times pretest anxiety between the two groups, (Z=−0.248, p=0.802), more difficult, 1.8 times more tiring, 1.8 times longer, 1.6 times intratest anxiety was 1.3 times higher (Z=−2.518, p=0.012) in more uncomfortable and 1.3 times more unpleasant than the the HVF group (1.69, 95% CI 1.52 to 1.85) than the HRT HRT group (p≤0.005 in all cases) (table 2). group (1.29, 95% CI 1.13 to 1.44). Looking specifically at the HVF group, intratest anxiety was Reliability 1.2 times higher (p=0.0001) than pretest anxiety (1.46, 95% For the reliability analysis, HVF subjects with >33% FPs, 33% CI 1.33 to 1.60). Comparatively, the HRT group showed a FNs or 20% FLs were included. In analysis of individual reliability indices (table 3), the average fixation loss rate was 7.7% (SD, 9.9%; range, 0– 56.2%), FP rate was 2.8% (SD, 3.2%; range, 0–18%) and FN rate was 3.1% (SD, 5.1%; range, 0–34.5%). The FP rate was found to correlate positively with pretest anxiety (Spearman’s r=0.313, p=0.001) and average MD (Spearman’s r=0.210, p=0.035). However, multiple linear regression analysis showed that pretest anxiety was the strongest predictor of a high FP rate (p=0.002). FN rate correlated with intratest anxiety (Spearman’s r=0.261, p=0.008), average MD (Spearman’sr=−0.566, p<0.0001), average PSD (Spearman’s r=0.525, p<0.0001), average test duration (Spearman’s r=0.602, p<0.0001) and age (Spearman’s r=0.288, p=0.003). Percentage of FL did not show any statistically significant correlations to the analysed parameters, however pretest anxiety was the strongest predictor of high FL to multiple linear regression analysis (p=0.072). To determine if any generalisation about the effect of anxiety on unreliability could be made, a composite parameter, ‘unreliability’, was calculated from an intereye average of all three reliability indices. Unreliability was found to correlate positively and significantly with pretest anxiety (Spearman’s r=0.273, p=0.006) and with test duration (Spearman’s r=0.309, p=0.002) (figure 3). Multiple linear regression analysis confirmed that these two variables were predictive of ‘unreliability’ (pretest anxiety, p=0.083; test duration, p=0.0016).

Figure 2 (A) Pretest and intratest anxiety in the Humphrey visual Severity field group. Grey represents pretest responses and black represents Twelve participants were excluded because of unreliable visual intratest responses. (B) Pretest and intratest anxiety in the Heidelberg fields (>20% FL or >33% FN or >33% FP) as the MD and retinal tomography group. Grey represents pretest responses and black PSD would be misleading. In this modified cohort, average MD represents intratest responses. was −3.4 dB (SD 5.0; range −27.6–2.1) and average PSD was

1130 Chew SSL, et al. Br J Ophthalmol 2016;100:1128–1133. doi:10.1136/bjophthalmol-2015-307110 Downloaded from http://bjo.bmj.com/ on August 30, 2016 - Published by group.bmj.com Clinical science

Table 2 Percentage of subjects scoring positively (≥Likert 2) with respect to the subjective measures for each of the tests Subjective measure/descriptor HRT (subjects≥Likert 2) (%)* HVF (subjects≥Likert 2) (%)* HVF: HRT ratio Z-score† p Value†

Pretest anxiety 34 36 1.0x −0.233 0.8016 Intratest anxiety 29 49 1.3x −2.498 0.0117 Difficult 43 74 1.6x −4.971 <0.0001 Tiring 9 63 1.8x −5.392 <0.0001 Long 11 64 1.8x −5.289 <0.0001 Uncomfortable 6 49 1.6x −4.461 <0.0001 Unpleasant 14 38 1.3x −2.834 0.0046 *Likert scale: 1=not at all, 2=a little, 3=moderately, 4=very, 5=extremely. †Mann-Whitney test: statistical significance, p<0.05. HRT, Heidelberg retinal tomography; HVF, Humphrey visual field.

3.9 dB (SD 2.8; range 1.2–12.9). MD and PSD were not signifi- high pretest anxiety, indicating that the participants most cantly different between men and women (p=0.43, p=0.97, anxious about their impending visual field test exhibited the respectively). Worsening MD and PSD were correlated with age highest combination of FL, FP and/or FN. Interestingly, reliabil- (Spearman’sr=−0.354, p=0.0003; Spearman’s r=0.384, ity was expressed in different ways depending on whether the p<0.0001, respectively), test duration (Spearman’sr=−0.832, patient was more anxious before the test or during the test. p<0.0001; Spearman’s r=0.835, p<0.0001, respectively), and Pretest anxiety was found to be a significant predictor of the FP FN rate (Spearman’sr=−0.566, p<0.0001; Spearman’s rate, perhaps reflecting a more ‘trigger-happy’ nature, while r=0.525, p<0.0001, respectively). Despite exclusion of partici- those more anxious during the test exhibited increased numbers pants with unreliable HVFs, multiple linear regression analysis of FN, missing points they should have responded to. highlighted ‘unreliability’ as a significant predictor of worse MD Pretest and intratest anxieties were not the only variables (p=0.0027) and confirmed age (p=0.0442) and test duration associated with poor reliability in visual field performance. FPs (p<0.0001) as significant predictors. correlated with worsening MD, as did FNs, which also correlated with worsening PSD, longer test duration and increasing DISCUSSION age. While it is unsurprising that older participants, with more fi Glaucoma is a chronic disease, which results in visual field loss severely depressed visual elds and who took longer to perform fi and may reduce quality of life.13 14 Visual field testing is an inte- the testing, had less reliable elds in terms of FPs and FNs, gral component of glaucoma management,15 but anecdotally interestingly these did not correlate with FLs. It should be noted many patients describe the testing procedure as a distressing or that the strong correlation found between FNs and worsening fi unpleasant experience. Recent research shows that patients rank MD corroborates the ndings of previous evidence showing that fi FNs correlate with disease severity in glaucoma, and thus repre- visual eld testing among the least popular procedures for evalu- 17 ating glaucoma progression.316 sent ocular rather than patient status. It is thought that the fi Generally, anxiety is acknowledged to negatively affect test higher FNs seen in eyes with glaucomatous eld loss may be performance.5 However, the present study is the first to quantify explained by increased variability in threshold sensitivities the magnitude of anxiety induced by visual field testing and during automated perimetry. Given the recognised relationship between age and trait document that heightened anxiety levels negatively impact on 18 reliability indices during visual field testing. In our study, unreli- anxiety, a baseline trait anxiety test was evaluated with age- ability in visual field testing was found to be associated with matched HVF and HRT groups. The trait anxiety level of the study sample was found to compare well with the normal population,6 and the two groups undergoing HVF or HRT testing were found to compare well with each other in their trait and pretest anxiety scores. However, despite the similarity in baseline trait scores and comparable levels of anxiety in anticipation of the test about to be undertaken, significant differences in response to the testing procedures were observed. The subjects in the HVF group, which requires significant levels of concentration and participation,19 20 reported significantly higher intratest anxiety than those in the HRT group, a test involving less active patient interaction.21 Looking more closely at each group, participants undergoing HVF testing had an increase in intratest anxiety compared with pretest scores indicating the experience may have been more stressful than expected. By comparison, those undergoing HRT testing showed a trend of decreased intratest anxiety compared with pretest scores, which is suggestive of the con- verse. Finally, those in the HVF group reported the test to be 60% more difficult, 80% longer, 80% more tiring and 80% more uncomfortable than those in the HRT group. Figure 3 Correlation between Test ‘Unreliability’ and Pretest Anxiety. Researchers have observed a learning effect in some patients Spearman’s r=0.27, p=0.06. with respect to perimetry,19 20 but this has typically been

Chew SSL, et al. Br J Ophthalmol 2016;100:1128–1133. doi:10.1136/bjophthalmol-2015-307110 1131 Downloaded from http://bjo.bmj.com/ on August 30, 2016 - Published by group.bmj.com Clinical science

Table 3 Spearman’s correlation coefficients for HVF reliability factors Pretest anxiety Intratest anxiety Average MD Average PSD Average test duration Age Sex

Fixation losses Spearman’s r 0.172 0.035 0.102 −0.040 0.069 0.061 −0.013 p Value 0.084 0.724 0.309 0.688 0.490 0.542 0.895 False positives Spearman’s r 0.313 0.138 0.210 −0.087 0.020 0.069 0.040 p Value 0.001 0.166 0.035 0.386 0.841 0.490 0.691 False negatives Spearman’s r 0.114 0.261 −0.566 0.525 0.602 0.288 −0.038 p Value 0.253 0.008 <0.0001 <0.0001 <0.0001 0.003 0.705 ‘Unreliability’ Spearman’s r 0.273 0.157 −0.089 0.178 0.309 0.194 −0.033 p Value 0.006 0.120 0.381 0.078 0.002 0.054 0.746 HVF, Humphrey visual field; MD, mean deviation.

measured in terms of establishing an adequate baseline rather such as duration since previous testing and whether patients than against reliability indices or anxiety. In the current study, knew what testing would be required are likely to affect significant decreases in reported pretest and intratest anxiety anxiety.4 Although pretest anxiety did not differ significantly levels occurred after exposure to 10 or more procedures. While between the HVF and HRT groups, the impact of these factors repeated testing may be of benefit, the completion of 10 tests to on multivariate models of anxiety in HVF testing would benefit overcome anxiety effects would be difficult to justify, but it does from being further elucidated. suggest a potential benefit of allowing patients the opportunity In conclusion, this study confirmed that automated visual to practise the test. field testing induces anxiety and that this has an impact on test The recognition that visual field testing induces anxiety is the reliability. Clinicians should acknowledge this anxiety with their first step in developing targeted strategies to improve test reli- patients and make attempts to reduce it in order to improve ability and overall patient experience. A qualitative survey of patient experience and test reliability. Patients with considerable patients undergoing visual field testing raised interesting insights experience of the test procedure were less anxious, showing into factors that patients believed to hinder their test perform- scope for improving test reliability through decreased anxiety. ance.4 Environmental factors such as increasing number of Further research should be directed at pretest interventions and other patients in the room, staff members talking loudly and the measurement outcomes to evaluate the efficacy of these time of day were identified as important interfering factors. initiatives. Patients also reported that they found it reassuring to have a staff member with them during testing. Effective task communi- Contributors Substantial contributions to the conception or design of the work: fi SSLC, NMK, HVD-M, JPC; acquisition, analysis or interpretation of data for the work: cation was identi ed as an important factor in test performance SSLC, NMK, C-YC, HVD-M; drafting the work or revising it critically for important and simple strategies such as the use of a standardised pretest intellectual content: SSLC, NMK, ABCW; and final approval of the version to be instructional video has been shown to increase test reliability.22 published: SSLC, NMK, JPC, HVD-M. This communication also extends to explanation of the results Funding The Allergan NZ Optic Nerve Clinical Research Fellowship in part and hence it was suggested by Glen et al4 that development of supported this work. simplified results specifically for patients might aid patient Competing interests None declared. understanding. Patient consent Obtained. There are some limitations to this study that we acknowledge. Ethics approval Health and Disability Ethics Committee New Zealand. It was necessary to exclude 12 participants with unreliable visual fields from our severity analysis, however we acknowledge Provenance and peer review Not commissioned; externally peer reviewed. that this risks excluding a proportion of participants with severely affected visual fields from glaucoma who, as previously fl REFERENCES mentioned, can have an elevated FN rate due to uctuating 1 Giangiacomo A, Garway-Heath D. Diagnosing glaucoma progression: current 17 threshold sensitivities from the disease process. Similarly, practice and promising technologies (vol 17, pg 153, 2006). Curr Opin Ophthalmol this may have affected our combined index of ‘unreliability’, 2006;17:325–5. which simplifies the effect of anxiety on overall reliability. Also, 2 Kwon YH, Fingert JH, Kuehn MH, et al. Mechanisms of disease: primary open-angle glaucoma. N Engl J Med 2009;360:1113–24. almost all of our participants undergoing HVF testing (98%) 3 Gardiner SK, Demirel S. Assessment of patient opinions of different clinical tests had undergone previous HVF testing and thus our results are used in the management of glaucoma. Ophthalmology 2008;115:2127–31. not reflective of anxiety induced by a new test. This discrepancy 4 Glen FC, Baker H, Crabb DP. A qualitative investigation into patients’ views on in experience level between the HVF and HRT groups may visual field testing for glaucoma monitoring. Bmj Open 2014;4:e003996. have also lead to an underestimation of the magnitude by which 5 Frierson HT Jr, Hoban JD. The effects of acute test anxiety on NBME Part I performance. J Natl Med Assoc 1992;84:686–9. anxiety increases in HVF testing. It was shown in the current 6 Spielberger C. Manual for the State-Trait Anxiety Inventory. Palo Alto, CA: study that more experienced participants (>10 previous HVF Consulting Psychologists Press, 1983. tests) had decreased intratest anxiety hence if HVF participants 7 Donham GW, Ludenia K. Cross-validation of the State-Trait Anxiety Inventory with – with similar levels of experience to the HRT group had been an alcoholic population. J Clin Psychol 1984;40:629 31. 8 Quek KF, Low WY, Razack AH, et al. Reliability and validity of the Spielberger recruited, we might have expected observation of an even larger State-Trait Anxiety Inventory (STAI) among urological patients: a Malaysian study. difference in anxiety. Qualitative studies have shown that factors Med J Malaysia 2004;59:258–67.

1132 Chew SSL, et al. Br J Ophthalmol 2016;100:1128–1133. doi:10.1136/bjophthalmol-2015-307110 Downloaded from http://bjo.bmj.com/ on August 30, 2016 - Published by group.bmj.com Clinical science

9 Davey HM, Barratt AL, Butow PN, et al. A one-item question with a Likert or Visual 16 Danesh-Meyer HV, Papchenko T, Savino PJ, et al. In vivo retinal nerve fiber layer Analog Scale adequately measured current anxiety. J Clin Epidemiol thickness measured by optical coherence tomography predicts visual 2007;60:356–60. recovery after surgery for parachiasmal tumors. Invest Ophth Vis Sci 10 Bicklerbluth M, Trick GL, Kolker AE, et al. Assessing the utility of reliability indexes for 2008;49:1879–85. automated visual-fields—testing ocular hypertensives. Ophthalmology 1989;96:616–19. 17 Bengtsson B, Heijl A. False-negative responses in glaucoma perimetry: Indicators of 11 Birt CM, Shin DH, Samudrala V, et al. Analysis of reliability indices from Humphrey patient performance or test reliability? Invest Ophth Vis Sci 2000;41:2201–4. visual field tests in an urban glaucoma population. Ophthalmology 18 Barnes LLB, Harp D, Woo SJ. Reliability generalization of scores on the spielberger 1997;104:1126–30. state-trait anxiety inventory. Educ Psychol Meas 2002;62:603–18. 12 Katz J, Sommer A, Witt K. Reliability of visual field results over repeated testing. 19 Heijl A, Lindgren G, Olsson J. The effect of perimetric experience in normal subjects. Ophthalmology 1991;98:70–5. Arch Ophthalmol 1989;107:81–6. 13 Béchetoille A, Arnould B, Bron A, et al. Measurement of health-related quality of 20 Kulze JC, Stewart WC, Sutherland SE. Factors associated with a learning effect in life with glaucoma: validation of the Glau-QoL 36-item questionnaire. Acta glaucoma patients using automated perimetry. Acta Ophthalmol (Copenh) Ophthalmol 2008;86:71–80. 1990;68:681–6. 14 McKean-Cowdin R, Wang Y, Wu J, et al. Impact of visual field loss on 21 Rohrschneider K, Burk RO, Völcker HE. Reproducibility of topometric data health-related quality of life in glaucoma: the Los Angeles Latino Eye Study. acquisition in normal and glaucomatous optic nerve heads with the laser Ophthalmology 2008;115:941–8.e1. tomographic scanner. Graefes Arch Clin Exp Ophthalmol 1993;231:457–64. 15 Sample PA. What does functional testing tell us about optic nerve damage? Surv 22 Shearfat H, Spry PGD, Waldock A, et al. Effect of a patient training video on visual Ophthalmol 2001;45(Suppl 3):S319–24; discussion S32–4. field test reliability. Brit J Ophthalmol 2003;87:153–6.

Chew SSL, et al. Br J Ophthalmol 2016;100:1128–1133. doi:10.1136/bjophthalmol-2015-307110 1133 Downloaded from http://bjo.bmj.com/ on August 30, 2016 - Published by group.bmj.com

Anxiety in visual field testing

Shenton S L Chew, Nathan M Kerr, Aaron B C Wong, Jennifer P Craig, Chi-Ying Chou and Helen V Danesh-Meyer

Br J Ophthalmol 2016 100: 1128-1133 originally published online November 25, 2015 doi: 10.1136/bjophthalmol-2015-307110

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