AOV - MST2

range of pupil diameter and retinal illuminance.

Diameter ranges from approx. 2 to 8 mm → 16-fold change in retinal illuminance, within 1-3 seconds

area is squared ---> 2 squared = 4, 8 squared = 64.... 64/4 = 16

this is where the 16 comes from

small v large pupil

• diffraction v aberrations

• depth of focus

small pupil

• Vision through a small pupil is limited by diffraction

• large depth of focus

large pupil

• Vision is limited through a large pupil by aberrations

• limited range. when u move off focus distance is blurred

what is the optical pupil size for limiting diffraction and aberrations

~3-4 mm

what does the posterior iris rest on?

lens

myosis vs mydriasis - pupil size

< 4 mm = “miosis” (constricted), > 4 mm = “mydriasis” (dilated)

physiological vs non-physiological anisocoria. pupil size

physiological anisocoria: normal difference in pupil sizes

• less than 1 mm

• most ppl have some asymmetry

non-phyiological (abnormal)

• more than 1 mm

difference in brown, blue and green irises

Melanocytes (determine eye colour)

• Lots → absorption → brown

• None → scatter → blue

• Some → brown + blue → green

does colour eyes affect drug absorption?

yep

lighter iris = more effective drops

Dilator pupillae:

• innervation

• neurotransmitter

• receptor

• muscle type

• action

• Radial muscle (fibres oriented like spokes, towards/away from pupil)

• Sympathetic innervation

  • Neurotransmitter: noradrenaline

  • Receptor: adrenergic (α₁)

• Action

  • Dilation (mydriasis): Activation of the dilator

  • Constriction (miosis): Relaxation of the dilator

Sphincter pupillae:

• innervation

• neurotransmitter

• receptor

• muscle type

• action

• Circular muscle (fibres oriented around the pupil)

• Parasympathetic Innervation

  • Neurotransmitter: acetylcholine

  • Receptor: muscarinic

• Actions:

  • Constriction (miosis): Activation of the sphincter

  • Dilation (mydriasis): Relaxation of the sphincter

3 types of input the pupil responds to

1. Light reflex (both direct and consensual)

2. near reflex

3. autonomic arousal

• fight or flight

• fear

• sex

• startle

• maximise retinal illumination when under pressure

• pupil constricts when tired or non-aroused

is depth of field greater at near or distance?

NEAR

• pupil constricts and increases depth of field

Afferent (sensory) limb - pupillary light reflex pathway

• This is the pathway for:
  “Shine light in the eye → pupils constrict.”

light enters retina:

• retina

• retinal ganglion cells

• optic nerve (CN II)

• optic chiasm (decussation)

• optic tract

• pretectal nucleus (midbrain)

• this tells the brain: light has entered this eye

Efferent (motor) limb - motor output pathway from brain back to eye

This is the pathway for:
“Shine light in the eye → pupils constrict.”

• from central pathway (pretectal nucleus)

• what reflex is this? What causes the direct and concensual response

central pathway:

Pretectal nucleus → both Edinger-Westphal nuclei (bilaterally)

efferent pathway:

oculomotor nerve CN III (parasympathetic fibres) → ciliary ganglion (preganglionic synapse) → short ciliary nerves → sphincter pupillae → constriction

The key point is both Edinger-Westphal nuclei are activated, so both pupils constrict.

• this is due to decussation!

• this is parasympathetic light reflex

what is the near triad

• Accommodation

• Convergence

• Pupillary constriction

Pupillary near reflex pathway

Afferent (Sensory) Limb

• pupil constriction

• accommodation

Retina → Retinal ganglion cells → Optic nerve (CN II) → Optic chiasm → Optic tract → Lateral geniculate nucleus (LGN) of thalamus → Primary visual cortex (V1) (occipital lobe) → Superior colliculus and parietal cortex (accommodation centres)

Pupillary near reflex pathway

Efferent (Motor) Limb

• pupil constriction

• accommodation

• what

central pathway:

Visual cortex and parietal cortex neurons → both Edinger-Westphal nuclei (bilaterally)

efferent pathway:

oculomotor nerve CN III (parasympathetic fibres) → ciliary ganglion → short ciliary nerves → sphincter pupillae → constriction

• Short ciliary nerves → Ciliary muscle Lens accommodation → constriction

• this is parasympathetic near reflex (ACh - mediated)

• antagonistic pathway to accommodation = sympathetic innervation (noradrenaline mediated)

main difference between near and light pupillary reflex

Main difference:

Reflex	Main pathway
Light reflex	Retina → pretectal nucleus → Edinger-Westphal
Near reflex	Retina → LGN → visual cortex/parietal areas → Edinger-Westphal

Both eventually use the same final parasympathetic output:

Edinger-Westphal → CN III → ciliary ganglion → short ciliary nerves → sphincter pupillae.

If the pretectal nucleus is damaged, what will it impact?

• we will have issues with direct and consensual light reflexes but not near

• the near pathway does not pass the pretectal nucleus!

passive vs volitional:

• light reflex

• near reflex

light reflex = passive

near reflex = volitional (but even blind ppl can do this 🙂 don’t have to be able to see)

types of pathways:

light

near

arousal

pupil is innervated by the autonomic nervous system

light = parasympathetic (constrict)

near = parasympathetic (constrict)

arousal = sympathetic (dilate)

Sympathetic Pathway

• EFFERENT (MOTOR) LIMB PATHWAY ONLY!

This is the pathway for:
Arousal/fight-or-flight/darkness → pupil dilates.

Hypothalamus → Sympathetic preganglionic neurons in intermediolateral column (T1-T2 spinal cord)

Preganglionic Fibres: Exit via T1-T2 spinal nerves → Superior cervical ganglion (in neck)

Postganglionic Fibres: Travel along internal carotid artery → Cavernous sinus → Ophthalmic division of CN V → Long ciliary nerves → Dilator pupillae muscle Pupil dilation

• T1/T2 are near the lung

• travel up the neck and synapse

what nerves are involved in:

• light

• near

• arousal (sympathetic) pathways

Light

• afferent: Optic nerve (CN II)

• efferent: Oculomotor nerve (CN III)

Near

• afferent: Optic nerve (CN II)

• efferent: Oculomotor nerve (CN III)

Arousal

• efferent: Trigeminal nerve (ophthalmic division) (CN V)

Where do the efferent pathways for parasympathetic and sympathetic innervation of the pupillary muscles meet? Where do they travel?

Ciliary ganglion

• The sympathetic fibres do not synapse here, but “tag along” for the ride

• Together they travel as the short ciliary nerve, to supply the iris sphincter and ciliary body (parasympathetic fibres) and the iris dilator (sympathetic fibres)

• i think the dilator goes thru long fibres

Describe supranuclear inhibition of the pupil. Inhibition of pupil constriction to light (what structures are involved… 2)

• give some examples of when we’d do this (3)

• higher brain centres can override pupillary light reflex thru descending inhibitory pathways to the pretectal nucleus and Edinger-Westphal nucleus

• inhibit parasympathetic output = reduced/absent pupil constriction

examples:

• near response: accommodation - pupil constricts in dim light

• arousal/attention - sympathetic activation dilates pupil overriding light reflex

• ciliospinal reflex - neck pinch causes dilation, suppressing light response

Through pupil testing we can determine the function of (3)

• Afferent nerves (leading away from the eye)

• Efferent nerves (leading towards the eye)

• Pupillary muscle function and other iris abnormalities

what target do we use when measuring pupil size

distant target

What kind of problem is it when anisocoria is greater in bright light? (diff pupil size in bright light)

• what are potential diagnoses’ ?

suggests a parasympathetic problem

• Bright light normally makes pupils constrict.

• So if the difference is bigger in bright light, the larger pupil is suspicious because it is not constricting properly.

• That suggests a parasympathetic problem.

Diagnosis

• CN3 palsy

• Aides tonic pupil

  • constricts a bit in light, but other eye constricts more due to concentric response

• Traumatic iris damage

• angle closure glaucoma (ACG)

• pharmacologic pupil dilation

  • optom/med/nursing students, malingerers (pupil tyring to fake neurological condition)

What kind of problem is it when anisocoria is greater in dim light? (diff pupil size in dim light)

• what is one diagnoses and three symptoms of this condition

suggests a sympathetic problem

• one eye is not dilating as well when light removed

Diagnosis

• HORNERS syndrome

  • Miosis (pupil constriction) – loss of sympathetic innervation to dilator pupillae

  • Ptosis (eyelid drooping) – loss of sympathetic innervation to Müller’s muscle

  • Anhidrosis (decreased sweating) – loss of sympathetic innervation to sweat glands

pupil reaction: speed of constriction and dilation

• draw graph

pupils are slow

• takes nearly a second for the pupil to constrict to about 90% of maximum

• re-dilation is slower, not being able to complete even after 3 seconds

• important for flashlight test!! Don’t want to go to quickly

what do u test RAPD in dim conditions?

• don’t want the pupils to already be constricted

RAPD swinging flashlight test: describe the direct and consensual responses when light is removed and shone into eyes.

• healthy vs diseased patient

• how long do u shine light into each eye

• When it first lands on one eye, there is a stimulus to dilate (consensual, due to light removed from the other eye) as well as to constrict (direct)

• In a healthy patient, there is net constriction since the direct pathway is stronger

Marcus Gunn Pupil

• represents a problem with the afferent system

• In diseases of the optic nerve/retina, the affected side (or worse side if bilateral) produces a weak direct response (or none, if severe)

• This allows the consensual response to dominate, so the worse eye dilates when the light is shone onto it! (grade 3-4+)

• In less severe cases, we see a small constriction (grade 1), or a pause (grade 2), followed by a greater re-dilation

• shine light into each eye for 3 seconds!

Pupil constricts to near (accommodation) but fails to constrict to light, despite intact afferent pathway

• what is affected and why?

Light and near reflexes use different neural pathways after the optic nerve

• Light reflex: Optic nerve → Pretectal nucleus → EWN

• Near reflex: Optic nerve → LGN → Visual cortex → EWN

Light reflex: Absent/reduced

Near reflex: Normal

Pretectal pathway damage with preserved cortical pathway = light-near dissociation

Causes

• Classic Causes‒ Argyll Robertson pupil (neurosyphilis) bilateral, small, irregular pupils

• Dorsal midbrain syndrome (Parinaud) pineal tumour, upward gaze palsy

• Diabetes, MS, midbrain stroke, trauma

Why is it important to understand pupil pathways

• help interpret any abnormal pupil results

What is the visual field?

The area of one’s surroundings that is visible at one time, with a steadily fixating eye

what does the Amsler grid detect? What are two examples?

central visual disturbances

• Scotomas (missing areas in vision) – severe retinal/optic nerve disease

• Metamorphopsia (distorted lines) – subtle macular disorders

When would you use an Amsler grid on a patient?

Patients with central visual symptoms, such as:

Unexplained decreased visual acuity

Macular pathologies, (eg: age-related macular degeneration)

How much does each square subtend?

1 degree. Central is 10 degree radius from the middle.

The standard chart used in every case. Consists of a 5mm square, white grid each subtending approximately 1°, on a black background with a central, which fixation target.

Amsler grid:

• distance

• Rx or no?

• monocular or binocular?

• wear habitual reading prescription, view monocularly

• held 28-30 cm away

• view monocularly

Amsler grid procedure

Monocular!

Ask the patient to always fixate on the central black dot

1. is the central dot clear and single?

2. Can you see all 4 corners of the larger square?

3. Are any of the vertical/horizontal lines missing, wavy or distorted?

4. Are there any black or missing patches?

Repeat for the other eye!

What can confrontation detect? What does it test for? What is it effective and not effective for detecting?

large, absolute scotomas. tests for neglect and extinction

• highly effective for post chiasmal defects (detects 9 out of 10)

• less sensitive for pre chiasmal defects (detects 1 out of 3)

what is the minimum mandatory evaluation for visual field assessment in driving license requirements?

confrontation

confrontation

• distance

• with or without Rx?

• monocular or binocular

• repeat how many time?

• must be at eye level with hands 50 cm from Px

• habitual Rx

• monocular

• test both hemi-fields twice to confirm, and repeat for other eye

what is neglect and extinction: confrontation

Neglect - The patient misses one side/quadrant even when you test it by itself.

Example:

• Left target alone → misses it

• Right target alone → sees it

• Left + right together → misses left again

Extinction - The patient can see both sides when tested separately, but when you show both at the same time, one side “loses the competition.”

Example:

• Left target alone → sees it

• Right target alone → sees it

• Left + right together → only reports right

Red cap

• distance

• what it test

• monocular or binocular?

• 40 cm

• monocular

• function of optic nerve

red cap procedure

• normal reading?

1. start with good eye

2. Tell me what colour this cap is

3. On a scale of 1 to 10, with 1 being the dimmest and 10 being the brightest, if this is 10/10 (present to one eye), how would you rate the brightness of this red cap in the other eye (present to other eye)?”

• An asymmetry of >2 between the eyes is a fail

What does perimetry measure? What are the 2 types of perimetry?

Measure of visual function (sensitivity) outside the fovea (i.e. across the visual field)

2 types: static and kinetic

• static what we usually use

What disease is perimetry essential for detecting and managing?

Glaucoma

• also useful for detection of neurological disorders and retinal disease

IF a disorder is detected using perimetry, what is the next step

Neuroimaging (MRI, CT-scan) used once disorder detected

what is the Bjerrum Screen?

a form of kinetic perimetry

• mostly used in research. sometimes used in low vision cases with large areas of vision loss

• useful for central scotoma

  • -Tangent screen (at 1 to 3 m)- Limited to central 30° to 50°- Must use 3 targets to fully evaluate scotoma

  • Target Size (mm)/Test distance (mm) COLOUR- e.g. 1/1000 W

3 types of perimetry that we learned in this lecture

1. Bjerrum screen (form of kinetic perimetry)

2. Goldmann perimeter

3. Standard automated perimetry

• first one mostly used in research, second not used as much

what is the goldmann perimeter used for monitoring?

retinal degenerations

• advance target of specific size and intensity inward until patient sees

describe standard automated perimetry. What is performance compared to?

• Measures sensitivity to small white lights against a dimly illuminated background

• look at orange dot, click when you see lights

• make them dimmer until they can’t see

• Performance is compared to an age-matched normative database

3 types of perimetry field analysers?

1. Humphrey visual field analyser

2. medmont visual field analyser

3. melbourne rapid fields

label….

• if we want to measure the right eye what side would chin go on

what are the 2 typical test patterns for the Humphrey Field Analyser (standard automated perimetry)

Humphrey Field Analyzer (HFA) uses a grid pattern

Patterns specified as X-Y:

• where X is the extent of coverage (deg)

• Y is 1 if on midlines or 2 if offset from midlines

what are the 4 test patterns for the Medmont visual field analyser? What degrees are they at (standard automated perimetry)

Medmont uses a radial pattern

Patterns specified as:

• Macular = 10°

• Central = 30°

• Glaucoma = central 30°and out to 50° nasally

• Peripheral = 50°

What are the 2 types of Test Protocol for Standard Automated Perimetry?

1. Screening - cannot be used to diagnose

2. Threshold - diagnostic

4 principal aspects of eye examination. What impacts this?

1. refractive status

2. binocular vision

3. Ocular health discussion

4. Review discussion

• but should be led by the patient

• age helps define the examination! Also accommodation?

where do we get information on what a clinical guidelines on routine exams?

Optometry Australia

• determine competency standards

medicare item number description

• should be longer than 15 mins

what competency standard domains does Optometry Australia account for?

1. Clinical care provider (look at this particularly!)

• history

• plan exam based on history taking

• establish diagnosis

• implement an appropriate management and treatment plan. management plan can be broad!! NOT JUST SPECS

• prescribe optical devices and medicines appropriately

• record all relevant info

1. professional and ethical practitioner

2. communicator and collaborator

3. scholar and lifelong learner

4. quality and risk manager

Factors of condition that impact examination

• how common is condition

• to dilate or not to dilate? Use of OCT?

• The value of early detection

• Time - can’t do everything!

what do we swear by in the code of ethics?

to keep the visual welfare of the patient uppermost at all times

structure of general eye examination

1. History taking

2. Measure of VA

3. screening tests (OM, NPC, CT, pupils, PD, confrontation/red cap, stereo, amsler, colour vision)

4. Retinoscopy

5. Refraction - distance

• more that we haven’t learned yet!

what are the 3 bodies and what they do?

AHPRA: Australian Health Practitioner Regulation Authority - Regulatory body

• optometry board of Australia is part of AHPRA

• determine record keeping rules of optometrist

OCANZ: Optometry Council of Australia and New Zealand - Accreditation body

OA: Optometry Australia - professional body

5 areas of history

Presenting Complaint (PC)

Patient ocular history (POH)

Family ocular history (FOH)

General Health (GH)

Visual tasks (VT)

Presenting complaint questions:

Some use LOFTSEA

Location/laterality

Onset

Frequency/progression

Type/Severity

Self treatment and its effectivity

Effect on patient

Associated signs or symptoms

Questions to ask if they are not presenting complaint

How is your vision?

• distance - driving, TV

• near - phone/reading

• intermediate - computer

• do you use glasses for these tasks

Symptoms to ask everyone

• sore eyes, red eyes, itchy eyes

• flashes floaters

• HA related to eyes

• Double vision

questions to ask in POH (patient ocular history)

Previous visits

Eye operations

Eye injuries

Eye infections

First glasses

Previous practitioners

Turned lazy eye (children maybe adults) - not a routine question

what to ask for in FOH (family ocular history) `

Glaucoma, Cat, Macular Degeneration

Turned/lazy eye/patching (if child)

diabetes, hypertension, heart disease

High rx or Blindness - not always routine

General health/Medical history questions - history taking

Start with open question

• how is your general health?

• history of diabetes, high blood pressure (heart disease sometimes asked but not usually)

• Medications?

• Allergies

• Smoking - sometimes

• GP name and address, how often they see - sometimes I think

Visual task questions - history taking

• driving - with or without Rx

• Occupation - computer use - idk most ppl are…. maybe don’t ask abt computers unless natural

• Hobbies with visual demand

If patients present with particular problem (flashes/floaters, double vision), what are the MAIN important next questions:

Eg flashes and floaters

• floaters = less worrysome

• might be how long do flashes last?

• What colour are the flashes?

Eg double vision might be

• Want to be sure that you are really getting double vision vs blur so are we definitely seeing two images or one with a fuzzy second

• Is the double vision two images side by side or two images once above the other

when is a good time to use open ended questions - history

at the beginning!

leading vs direct vs indirect questions

• I think generally:

  • leading points you in a specific direction

  • direct is usually yes or no

  • indirect has to give some sort of other response

3 professionalism themes

1. Providing care that is in the best interests of patient and their carers, and warrants the respect and trust of the community

2. Practicing in a manner that is consistent with the regulatory and professional requirements

3. Engaging in reflective and evidence-based practice to continually improve knowledge and skills and providing care that prioritises effective and equitable use of health resources

5 Professionalism themes when should be able to unpack

1. Define a profession and describe professionalism

2. identify professional behaviours and how they apply to interaction with peers

3. Recognise the impact of bias including unconscious bias in healthcare

4. Define honesty, respect, integrity and responsibility in healthcare

5. Identify the diverse nature of optometric patients and describe additional needs that may be requeired when providing care

define unconscious bias

subconscious attitudes, stereotypes, and automatic assumptions people hold about others based on factors like race, gender, age, or appearance

what is screening (Test Protocol for Standard Automated Perimetry) good for and not good for?

• not diagnostic!

good for:

• elderly, cortical defects, learning/training

not good for:

• subtle defects

• diagnosis

• monitoring disease progression

what is threshold (Test Protocol for Standard Automated Perimetry) good for and not good for?

Must be used if you are:

• Confirming a defect Monitoring for stability (treatment effectiveness)

• Monitoring for progression

Might not be suitable for:

• Patients with limited attention spans

• Patients with a disability (e.g. shaking palsy, tremor)

difference between screening and threshold - Standard Automated Perimetry

screening

• stimulus of fixed intensity - lights of fixed intensity

• approx 2 mins per eye

• can’t be used to diagnose

dignostic

• making lights dimmer and dimmer until patient doesn’t click anymore

• uses a test strategy (faster = less reliable). A bit of a trade off

What can defects tell us about where in the visual pathway it is

Depending on the test and stuff, and failed, then did SAP to investigete. Good chance you could trace it back to part in the visual pathway depending on where the defect is!

What is the most important sections of the standard automated perimetry print out? (3)

1. Pointwise analysis

• Patient threshold values compared to age-matched norms.

• A cluster of dark boxes on the probability maps could indicate visual field loss

2. Regional analysis

• Glaucoma Hemifield Test. Looks for differences between the superior and inferior visual field

2. Global indices

• three values:

  • 1. Visual Field index

  • Mean Deviation

  • Pattern Std Deviation

  • these indices consider all points in the visual field and compares to age-matched norms

• general info. Higher numbers indicate dim light could be detected, lower corresponds to brighter lights

• there are reliability indices that are indicators of reliability

• greyscale plot just for info

What doe