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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 113  |  Issue : 2  |  Page : 54-68

The effect of pupillary dilatation on visual field testing in glaucoma


1 Ophthalmology Department, Dar El Shefaa Hospital, Cairo, Egypt
2 Department of Ophthalmology, Faculty of Medicine, Ain Shams University, Cairo, Egypt

Date of Submission29-Mar-2020
Date of Acceptance04-Apr-2020
Date of Web Publication10-Jul-2020

Correspondence Address:
MSc, MD, PhD Mervat S Mourad
Department of Ophthalmology, Faculty of Medicine, Ain Shams University, Cairo
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ejos.ejos_15_20

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  Abstract 

Introduction The concern on the effect of pupillary dilatation on visual field parameters in patients with glaucoma comes from the fact that patients usually seek field examination after their pupils have been dilated for fundus examination.
Aim To investigate the influence of pupillary dilatation on visual field testing in patients with glaucoma, by using automated static perimetry.
Patients and methods A prospective comparative noninterventional clinical study was conducted on 20 eyes (11 patients) with open-angle glaucoma. Two consecutive visual field examinations were performed on each eye of all participants. The first was done on the undilated normal pupil size, whereas the second was done after dilating the pupil to 6–8 mm.
Results After pupillary dilatation, fixation losses were significantly higher. There was no significant difference in false-negative or false-positive results. There was improvement in the mean deviation with no statistical significance. Pattern standard deviation showed also improvement, which was statistically significant.
Discussion and conclusion It was found that pupillary dilatation caused variability and difference in the visual field parameters, which emphasizes the importance of consistent pupillary size in performing the serial automated visual field tests, especially in patients with glaucoma to allow standardized judgment on the patient’s progression.

Keywords: field of vision, glaucoma, pupillary dilatation


How to cite this article:
Salem DG, Mourad MS, Hamid MA. The effect of pupillary dilatation on visual field testing in glaucoma. J Egypt Ophthalmol Soc 2020;113:54-68

How to cite this URL:
Salem DG, Mourad MS, Hamid MA. The effect of pupillary dilatation on visual field testing in glaucoma. J Egypt Ophthalmol Soc [serial online] 2020 [cited 2020 Aug 14];113:54-68. Available from: http://www.jeos.eg.net/text.asp?2020/113/2/54/289486


  Introduction Top


It is frequently noticed that some of the patients prefer to undergo visual field testing, after having a previous fundus examination with pupillary dilatation, preferring not to wait to another appointment, which raises concerns on the effect of pupillary dilatation on visual field parameters in patients with glaucoma. Many studies have either investigated the effect of pupillary dilatation on visual field in normal participants or its effect in patients with glaucoma taking miotics, but still there existed few studies investigating the effect of pupillary dilatation in patients with glaucoma not taking miotics [1].

In a study conducted on both mydriatic and miotic pupils in normal people, the isopter area of the dilated pupil generally decreased. Therefore, careful attention should be paid to changes in the isopter area associated with changes in the pupil size [2].


  Aim Top


The aim of the study is to investigate the influence of pupillary dilatation on visual field testing in patients with glaucoma, by using automated static perimetry.


  Patients and methods Top


This prospective comparative noninterventional clinical study was conducted on patients attending the Ophthalmology Outpatients’ Clinics of Ain Shams Specialized Hospital. The patients included in this study were clearly informed about the purpose of the study and the steps of examination and had to sign an informed consent before inclusion. Data collection was following the laws of Egypt and was compliant with the principles of the Declaration of Helsinki. It included 20 eyes (11 patients) with open-angle glaucoma. There were eight males and three females, and their ages ranged from 27 to 65 years.

Inclusion criteria

The following were the inclusion criteria:
  1. Age from 20 to 65 years.
  2. Patients with open-angle with glaucoma.
  3. Clear optic media.
  4. Best-corrected visual acuity more than 6/12.


Exclusion criteria

The following were the inclusion criteria:
  1. Opaque media.
  2. Best-corrected visual acuity less than 6/12.


Each patient included in this study was subjected to the following.

Ophthalmological examination

  1. Best-corrected visual acuity.
  2. Ocular tension measurements using Goldmann applanation tonometer.
  3. Slit-lamp examination to assess anterior segment, and exclude media opacity.
  4. Fundus examination using slit-lamp biomicroscopy.


Standard automated perimetry using Humphrey visual field analyzer (24-2, Stat Pac Program, Sita standard strategy, stimulus size III, white light, background illumination 31.5 Asb. Blind spot check size III).

Each participant underwent a manifest refraction for emmetropia, and their presbyopic correction was added in the perimetry lens frame, according to age. Then two consecutive visual field examinations were performed on each eye of all participants. The first examination was for undilated normal pupil size. For the second examination, tropicamide 1% (Mydriacyl 1%) eye drops were instilled in each eye, and the test was done after ensuring that each participant’s pupil size became at least 6–8 mm.

Procedures for examination using automated perimetry

  1. Instrument setup:
    1. Field analyzer was turned on.
    2. New patient data were entered.
    3. Corrective lenses was inserted in holder.
    4. Selecting the central 24-2 threshold program.
  2. Patient setup
    1. The patient was seated.
    2. Special occluder was fitted on the nontested eye.
    3. Test procedure was explained in detail.
    4. The patient was positioned: Chin rest, headrest adjustable up-down/back-forth.


Testing

  1. The test procedure was first demonstrated: demo test that lasts 1 min unless start is hit first where the field analyzer present test points, but the result will not be recorded during the demonstration test.
  2. Then the test was started.
  3. The test on the nondilated pupil was started with, then was followed by the test after pharmacological pupillary dilatation (separated by a 30-min rest). Both eyes were respectively tested.


Printing the test results

The results from the threshold test screen were printed immediately.


  Results Top


This study was conducted on patients attending the Ophthalmology Outpatient’s Clinics of Ain Shams Specialized Hospital. It included 20 eyes (11 patients) with open-angle glaucoma. There were eight males and three females ([Figure 1] and [Table 1]). Their ages ranged from 27 to 65 years, with a mean age of 49.05 years ([Table 2]) with SD 12.6. The visual fields were studied before and after pupillary dilatation.
Figure 1 Percentage of males and females in the current study.

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Table 1 Number and percent of males and females

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Table 2 Age range and mean

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The summary of the data before and after the pupillary dilatation and their mean difference and the probability value are shown in [Table 3].
Table 3 Summary of the results with mean difference and SD of the data before and after pupillary dilatation

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The reliability of each visual field test was assessed, and the test was considered reliable only if false-positive and false-negative rates were less than 25%. Those exceeding 25% were considered unqualified and were excluded. During the study, the fixation losses were significantly increased in patients after pupillary dilatation.

Fixation losses

Upon comparison between measurements before and after, there was a difference in fixation losses, being significantly higher after pupillary dilatation ([Table 4] and [Figure 2]).
Table 4 Fixation losses increased after pupillary dilatation with statistically significant value

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Figure 2 Fixation losses before and after pupillary dilatation.

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Examples of fixation losses from the study before and after pupillary dilatation are shown in [Figure 3] and [Figure 4].
Figure 3 Fixation losses before pupillary dilatation.

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Figure 4 Fixation losses in the same patient after pupillary dilatation.

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False positive

Upon comparison between measurements before and after, there was no significant difference in false-positive results ([Table 5] and [Figure 5]).
Table 5 False-positive results before and after pupillary dilatation

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Figure 5 False-positive results before and after pupillary dilatation.

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False negative

Upon comparison between measurements before and after pupillary dilatation, there was no significant difference in false negative results ([Table 6] and [Figure 6]).
Table 6 False-negative results before and after pupillary dilatation

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Figure 6 False-negative results before and after.

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Mean deviation

There was improvement in the mean deviation (MD) after pupillary dilatation, with no statistical significance, as in [Table 7], [Figure 7] and [Figure 8].
Table 7 Mean deviation before and after pupillary dilatation with no significant difference

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Figure 7 Mean deviation before and after pupillary dilatation.

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Figure 8 MD before and after pupillary dilatation. MD, mean deviation.

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The comparison of MD values before and after dilation is plotted in [Figure 8] (r=0.52, P=0.25).

Twelve (60%) eyes showed improvement in MD after pupillary dilatation, whereas eight (40%) had worsened MD after pupillary dilatation. [Figure 9] and [Figure 10] show examples of MD improvements before and after pupillary dilatation.
Figure 9 Mean deviation in one patient before pupillary dilatation with significant double arcuate scotoma, GHT is outside normal limits, and high PSD. GHT, glaucoma hemifield test; PSD, pattern standard deviation.

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Figure 10 Mean deviation in the same patient after pupillary dilatation with improvement in the mean deviation, and decrease in the depth and extent of the scotoma according to the pattern deviation plot. GHT shows general reduction of sensitivity, and also there is reduction in the PSD. GHT, glaucoma hemifield test; PSD, pattern standard deviation.

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Among the 12 eyes that showed improvement in the MD after pupillary dilatation, analysis showed that the MD and pattern standard deviation (PSD) had statistically highly significant improvement. The false-negative and fixation loss parameters showed statistically significant changes before and after pupillary dilatation. However, the false-positive showed no statistical significant changes ([Table 8]).
Table 8 Different data in the eyes which showed mean deviation improvement after pupillary dilatation

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The eight eyes that showed worsening of MD after pupillary dilatation had no statistically significant difference in any parameter before and after pupillary dilatation except for the MD, which showed highly statistically significant change ([Figure 11] and [Figure 12]).
Figure 11 Mean deviation in a male patient before pupillary dilatation, with P value less than 5%, reliable test with very low probability scotomata, and GHT test is within normal limits. GHT, glaucoma hemifield test.

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Figure 12 MD in the same male patient after undergoing pupillary dilatation is significantly worsened, with P value less than 0.5%. GHT became outside normal limits. Pattern deviation plot showing starting early upper arcuate scotoma, nasal step, and paracentral scotoma, all are characteristic of glaucoma defects. GHT, glaucoma hemifield test; MD, mean deviation.

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Pattern standard deviation

There was a statistically significant improvement in the PSD after pupillary dilatation (P<0.05) ([Table 9] and [Figure 13]).
Table 9 Pattern standard deviation before and after pupillary dilatation with statistically significant difference

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Figure 13 PSD before and after pupillary dilatation. PSD, pattern standard deviation.

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Among the 16 eyes that showed improvement in PSD after pupillary dilatation ([Figure 14] and [Figure 15]), the analysis showed that only the PSD and the fixation loss had statistically significant change before and after pupillary dilatation ([Table 10]).
Figure 14 PSD of a female patient’s right eye before pupillary dilatation. GHT outside normal limits, with double arcuate scotoma and enlargement of the blind spot. GHT, glaucoma hemifield test; PSD, pattern standard deviation.

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Figure 15 PSD of the same patient after pupillary dilatation showing improvement. PSD, pattern standard deviation.

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Table 10 Statistical data in eyes showing improvement in pattern standard deviation

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The four eyes that showed worsening of PSD after pupillary dilatation had no statistically significant difference in any parameter before and after pupillary dilatation. This is probably owing to the small sample size ([Figure 16] and [Figure 17]).
Figure 16 PSD in a patient before pupillary dilatation (P value less than 1%), with double arcuate scotoma (more dense) in the inferiorly, and GHT is outside normal limits. GHT, glaucoma hemifield test; PSD, pattern standard deviation.

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Figure 17 PSD in the previous patient after pupillary dilatation, with P value less than 0.5%. PSD, pattern standard deviation.

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  Discussion Top


The normal range of physiological changes in the size of the pupil, which ranges between 2 and 4 mm, does not have a noticeable influence on the retinal sensitivity [3].

The effect of pupillary dilatation on perimetric results was studied in a very similar study to this current study, where glaucomatous patients on timolol were tested before and after pharmacological mydriasis, which reported decrease in threshold values in patients with glaucoma [4].

Other studies included normal participants before and after mydriasis [1],[5]. Patients with glaucoma were not chosen OWING to the difficulty in examining the visual field several times in old patients with glaucoma, as the results may be less reliable owing to fluctuations in glaucomatous eyes, and the visual field defects would be varied according to the patient’s pathological status [5]. However, the main aim of this study was to investigate the effect of mydriasis on perimetry of patients with glaucoma specifically, to verify whether it is acceptable or not to undergo perimetry with dilated pupil, as part of glaucoma follow-up.

This study included 20 eyes of 11 patients with glaucoma, receiving different intraocular pressure lowering eye drops, comprising eight males and three females, with ages ranging from 27 to 65 years. Other studies included 23 patients with primary open-angle glaucoma treated with timolol, with mean age of 59.4±9.81 years [4], 18 patients with glaucoma receiving pilocarpine treatment [6], 36 eyes in 21 normal volunteers with mean age 30.1 years, ranging from 23 to 40 year [5], and 23 normal participants [1].

Variables in patients’ selection might account for the different results obtained from this study in contrast to other studies.

In this study, 24-2 program was chosen to decrease test time and also minimize fatigue effect as possible, without losing the essential data needed for follow-up of patients with glaucoma. The 24-2 testing strategy provides information comparable to that provided by the 30-2 strategy, in a shorter time and with less variability [7].

Results were compared using the paired Student’s t test. P value less than 0.05 was considered statistically significant.

Upon comparison between measurements before and after mydriasis, there was no significant difference between false positive and false negative, whereas there was difference in fixation losses, being significantly higher after mydriasis.

The percentage of false-positive strongly influence the MD with a 1 dB increase in MD per 10% increase in false positive [8].

Other studies did not find any differences in fixation losses, as well as false positive or false negative results before and after pupillary dilation [1],[4],[5],[6].

In spite of all the measures taken to reduce the fixation losses in the retests, such as eye tracker, head fixation, verbal commands, and repeating the blind spot calculation with carefully controlling fatigue, yet it was found that there was a significant increase in the fixation losses in the retests done. This does not match with any of the similar previous studies [1],[4],[5],[6].

As for fixation losses and variability of perimetry results, the isolated scotomata found in the visual fields of patients with glaucoma often have steep sensitivity profiles. Small inaccuracies of fixation can result in a stimulus falling inside a deep scotoma from a normal area or vice versa. In the presence of steep sensitivity profiles, inaccuracies of fixation can, therefore, result in an increase in variability when multiple estimates of threshold are made, a relationship between the number of edges in the visual field and test–retest variability [9], and the effects of fixation instability quantified in both normal experienced observers [10].

Fixation errors, though contributing to variability, are not the major cause of the increased variability seen at locations with reduced sensitivity [11].

Mydriasis is thought to have a minimal influence on visual field performance in healthy participants, other than reduced accommodation requiring appropriate correction. Accommodative dysfunction was carefully corrected in this study, by performing a manifest refraction before each visual field study.

With increased retinal illumination on pupillary dilatation, threshold sensitivity values would be expected to improve. This expected improvement may be reduced or eliminated by the Stiles-Crawford effect: rays of light entering the eye through the center of the pupil elicit a greater sensation of brightness than rays of light that pass through the pupil eccentrically [12].

The previous hypothesis cannot explain the insignificant improvement found in MD in this study.

In this study, mydriasis resulted in an insignificant improvement of MD, with difference of 0.31 dB (SD 2, P=0.25) between MD before and after mydriasis. This is in contrary to other studies that showed worsening of 0.73±0.87 dB (P=0.0001) [5]; also in another study, the MD worsened with a mean decrease of 0.27 dB (P=0.001) [13]; and another study showed MD loss of 1.15 dB (P=0.0001) [1]. There was also recorded significant impairment of the mean defect with an average decrease of 3.01 dB (SD 1.52 dB, P<0.001) [4].

Patient-specific information in this study showed that dilation with tropicamide 1% caused improvement of the MD in 12 (60%) eyes, whereas eight (40%) eyes had worsening of the MD after dilatation. However, in another study [4] that used phenylephrine for pupillary dilatation, false negatives on patient-specific information showed impairment of the mean defect in 100%, representing 23 eyes.

Worse MD and PSD are strongly correlated with increased false negatives which might be attributable to test fatigue [14].

The results of the current study shows increased variability in testing visual field of patients with glaucoma.

In this study, attempts to limit intertest variability were made, by testing and retesting within a short period. Patients also were monitored closely during the visual field examinations and were allowed rest periods as needed to minimize fatigue. Moreover, a comparison was made between the parameters in the first eye versus the second eye in dilated and undilated status to look for fatigue effects.

Han et al. [15], found no significant learning effect seen in the undilated eye, with no improvement in threshold sensitivity. In the current study, all patients had previous experience with computed threshold perimetry, and most of them had undergone many examinations of this type. In this group of participants, there was no apparent learning absence or fatigue effect between first and second eye tested.

The PSD best quantifies the amount of loss as well any progression of glaucoma in the early stages. Note that the PSD is not helpful in tracking advanced glaucomatous defects [16].

There was a statistically significant improvement in the PSD with mean 1.59 dB (SD 2.07, P<0.01). Other studies also found an improvement in the PSD, with a mean of 0.10 (P=0.199) after dilation, which was not statistically significant [13]. Improvement in the PSD and the corrected PSD was also reported with dilation by 1.42 dB (P<0.01) and 1.73 dB (P<0.05), respectively, after dilation with phenylephrine 10% [6]. However, other studies found impairment of the PSD [1],[5]. The PSD impairment reached 1.51 dB (SD 1.78 dB, P<0.01) [4]).

This study emphasizes the importance of consistent pupil diameter in serial visual field testing, because the interpretation of serial visual fields can be an invaluable aid to the physician in determining an appropriate intervention. It is imperative that test conditions that affect the outcome parameters, such as miosis and mydriasis, which is the main concern in this study, should be carefully controlled and monitored with successive follow-up tests.


  Conclusion and recommendations Top


It was found that pupillary dilatation after tropicamide 1% caused variability and difference in the visual field parameters, MD was not statistically altered, but the PSD showed statistically significant difference.

Therefore, this study emphasizes the importance of consistent pupillary size in performing the serial automated visual field tests, and patients with glaucoma must not undergo visual field testing with mydriasis, as it was found to affect the perimetric results, which can affect the clinician judgment on the patient’s progression.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Kudrna GR, Stanley MA, Remington LA. Pupillary dilation and its effects on automated perimetry results. J Am Optom Assoc 1995; 66:675–680.  Back to cited text no. 1
    
2.
Hirasawa K, Shoji N, Kobashi C, Yamanashi A. Effects of mydriasis and miosis on kinetic perimetry findings in normal participants. Graefes Arch Clin Exp Ophthalmol 2015; 253:1341–1346.  Back to cited text no. 2
    
3.
Wood JM, Wild JM, Bullimore MA, Gilmartin B. Factors affecting the normal perimetric profile derived by automated static threshold LED perimetry. I. Pupil size. Ophthalmic Physiol Opt 1988; 8:26.  Back to cited text no. 3
    
4.
Mendivil A. Influence of a dilated pupil on the visual field in glaucoma. J Glaucoma 1997; 6:217–220.  Back to cited text no. 4
    
5.
Park HJ, Youn DH. Quantitative analysis of changes of automated perimetric thresholds after pupillary dilation and induced myopia in normal subjects. Korean J Ophthalmol 1994; 8:53–60.  Back to cited text no. 5
    
6.
Rebolleda G, Munoz FJ, Femandez Victorio JM, Pellicer T, del Castillo JM. Effects of pupillary dilation on automated perimetry in glaucoma patients receiving pilocarpine. Ophthalmology 1992; 99:418–423.  Back to cited text no. 6
    
7.
Khoury JM, Donahue SP, Lavin PJ, Tsai JC. Comparison of 24-2 and 30-2 perimetry in glaucomatous and nonglaucomatous optic neuropathies: The Official Journal of the North American Neuro-Ophthalmology Society, 1999; 19:100–108.  Back to cited text no. 7
    
8.
Montollio FGJ, Wesselink C, Gordijn M, Jansonius NM. Factors that influence standard automated perimetry test results in glaucoma: test reliability, technician experience, time of day, and season. Invest Ophthalmol Vis Sci 2012; 53:7010–7017.  Back to cited text no. 8
    
9.
Henson DB, Bryson H. Is the variability in glaucomatous field loss due to poor fixation control. In Mills RP, Heijl A, eds. Perimetry update 1990/1991. Amsterdam: Kugler & Ghendini; 1991. 217–220  Back to cited text no. 9
    
10.
Vingrys AJ, Demirel S. The effect of fixational loss on perimetric thresholds and reliability. In: Mills RP, ed. Perimetric update 1992/1993. Amsterdam: Kugler & Ghendini: 1993. 521–526  Back to cited text no. 10
    
11.
Henson DB, Evans J, Lane CM. Fixation accuracy of patients with glaucoma during full threshold perimetry. In: Mills RP, Wall M, eds. Perimetric update 1994/95. Amsterdam: Kugler; 1995. 241–248  Back to cited text no. 11
    
12.
Records RE, Brown JL. Light and photometry. In: Duane TO, Jaeger EA, eds. Biomedical foundations of ophthalmology. Philadelphia: JB Lippincott Co 1988. 2.  Back to cited text no. 12
    
13.
Suram V, Chadaram B, Raj Kathuri P. Changes in the visual fields before and after pupillary dilatation. Int J Pharma Med Res 2015; 3:1.  Back to cited text no. 13
    
14.
Swaminathan S, Greenberg MB, Vanner EA, Cavuoto KM, Wellik SR, Chan CT. The effect of patient characteristics and sleep quality on visual field performance reliability. J Ophthalmol 2018; 2018:2731260.  Back to cited text no. 14
    
15.
Han RC, Jolly JK, Xue K, Maclaren RE, Phill D. Effects of pupil dilation on MAIA microperimetry. Clin Exp Ophthalmol 2017; 45:489–495.  Back to cited text no. 15
    
16.
Chaglasian M. (2013): Sharpen Your Visual Field Interpretation Skills. Review of Optometry. Retrieved February 2020, from https://www.reviewofoptometry.com/article/sharpen-your-visual-field-interpretation-skills.  Back to cited text no. 16
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10]



 

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