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Visual field interpretation.

Although typically used to aid in diagnosing or monitoring glaucoma, a visual field plot often tells us more than this. Practitioners should use their clinical expertise to interpret the field plots presented.

Optometrists

Therapeutic optometrists

01 What typically gives rise to the field plot shown in the image?

a) Lens rim artefact in high hyperopia

b) Lens rim artefact in high myopia

c) High astigmatism

d) Presbyopia

02 What does a sensitivity value of 'OdB' or '<0dB' mean on any perimetric instrument?

a) The patient has no vision at this location

b) The patient did not respond to the brightest stimulus presented by the perimeter

c) The patient did not respond to a stimulus of 3183.1 cd/[m.sup.2]

d) All of these options

03 How many sectors does the Glaucoma Hemifield Test (GHT) compare between the upper and lower hemifields in the Humphrey Field Analyzer?

a) 3

b) 4

c) 5

d) 6

04 The results from the GHT have been omitted from this image. What would it show for this patient?

a) Outside normal limits

b) General reduction of sensitivity

c) Abnormally high sensitivity

d) Borderline

05 What is the most accurate interpretation of the visual field defect shown in the image?

a) A nasal step

b) A general reduction in sensitivity likely caused by an optical factor, for example cataract, plus a nasal step

c) A quadrantanopia

d) The patient is 'trigger-happy'

06 What is the most appropriate course of action to take for this patient?

a) Dilate the pupils

b) Refer routinely

c) Refer urgently

d) Repeat the test

07 This patient presented with reduced visual acuity in the right eye. The visual field was full in the left eye. Dilated ocular examination was unremarkable and intraocular pressure was normal in both eyes. The patient had not experienced any previous ocular problems. What other test would aid diagnosis for this patient?

a) Colour vision

b) Stereoacuity

c) Gonioscopy

d) Pachymetry

08 How urgently should you refer this patient to an ophthalmologist (according to the College of Optometrists' guidelines)?

a) Within 24 hours (emergency referral)

b) Within one week (urgent referral)

c) Within three months (routine referral)

d) I would not refer this patient to an ophthalmologist

09 Should you refer this patient to another medical professional?

a) Yes, to their GP

b) Yes, to a neurologist

c) Yes, to a cardiologist

d) No

10 This patient has a homonymous quadrantanopia. Given the visual field shown for the left eye, what visual field defect would be found in the right eye'

a) Supero-nasal defect

b) Supero-temporal defect

c) Infero-nasal defect

d) Infero-temporal defect

11 Where in the visual pathway would you expect a lesion to cause a visual field defect of this type?

a) Pre-chiasmal

b) Chiasmal

c) Optic radiations

d) Visual cortex

12 What is the most common cause of this type of defect?

a) Trauma

b) Diabetes

c) Stroke

d) Tumour

Acknowledgements

Images courtesy of Heijl A, Patella VM, Bengtsson B (2012), The field analyzer primer: Effective perimetry. Carl Zeiss Meditec, Inc.

Exam questions

Under the enhanced CET rules of the GOC, MCQs for this exam appear online at www.optometry.co.uk. Please complete online by midnight on 26 July 2019. You will be unable to submit exams after this date.

Dr Lindsay Rountree BSc, PhD, MCOptom

* Dr Lindsay Rountree is an optometrist and post-doctoral research associate at Aston University. Her research interests include visual function, and how this is affected by disease or other factors.

Course code: C-70901 Deadline: 26 July 2019

Learning objectives

* Be able to interpret visual field plots (Group 3.1.5)

* Be able to interpret visual field plots and manage the patient appropriately (Group 2.1.2)

Caption: Image A

Caption: Image B

Caption: Image C

Caption: Image D
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Title Annotation:Visual fields
Author:Rountree, Lindsay
Publication:Optometry Today
Date:Jun 1, 2019
Words:632
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