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OCANZ COE study materials
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OCANZ COE practice questions

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Question 1Written examination (optometry knowledge and clinical reasoning)

Which corneal layer is primarily responsible for maintaining corneal transparency by regulating its hydration through a sodium-potassium ATPase pump?

  1. Corneal epithelium
  2. Bowman's layer
  3. Corneal endothelium Correct answer.
  4. Stroma

Explanation

The corneal endothelium is a single layer of cells on the posterior cornea that actively pumps fluid out of the stroma via Na+/K+-ATPase, keeping the stroma relatively dehydrated and thus transparent. Its barrier and pump functions are essential because endothelial cells do not regenerate appreciably in humans.

Question 2Written examination (optometry knowledge and clinical reasoning)

A patient reports sudden onset of a curtain-like shadow over the superior visual field that progressed over hours. Which condition should be highest on the differential?

  1. Retinal detachment Correct answer.
  2. Central serous chorioretinopathy
  3. Open-angle glaucoma
  4. Vitreous haemorrhage

Explanation

A painless, progressive curtain or shadow across the visual field is a classic symptom of retinal detachment, reflecting separation of neurosensory retina from the retinal pigment epithelium. Urgent dilated fundus examination and referral are required because delay risks permanent macular involvement.

Question 3Written examination (optometry knowledge and clinical reasoning)

Which structure produces the aqueous humour that fills the anterior chamber?

  1. Trabecular meshwork
  2. Ciliary epithelium Correct answer.
  3. Lens capsule
  4. Schlemm's canal

Explanation

Aqueous humour is secreted by the ciliary epithelium covering the ciliary processes, then flows through the pupil into the anterior chamber. It drains mainly via the trabecular meshwork into Schlemm's canal, so secretion and outflow together determine intraocular pressure.

Question 4Written examination (optometry knowledge and clinical reasoning)

A 6-year-old presents with reduced distance acuity, normal near acuity, and an esotropia at near fixation. Which refractive correction is most likely indicated?

  1. Full myopic correction
  2. Full hyperopic correction Correct answer.
  3. No correction if acuity is 6/9
  4. Partial hyperopic undercorrection

Explanation

Accommodative esotropia is driven by excessive accommodative convergence in uncorrected hyperopia, so the full cycloplegic hyperopic refraction is prescribed to relax accommodation and align the eyes. Undercorrection may leave residual esotropia and amblyopia risk.

Question 5Written examination (optometry knowledge and clinical reasoning)

Which visual field defect is most characteristic of a lesion at the optic chiasm?

  1. Homonymous hemianopia
  2. Central scotoma
  3. Altitudinal defect
  4. Bitemporal hemianopia Correct answer.

Explanation

The chiasm contains decussating nasal fibres from each eye, so a midline compressive lesion such as a pituitary adenoma produces loss of both temporal fields. Post-chiasmal lesions instead cause homonymous defects respecting the vertical midline.

Question 6Written examination (optometry knowledge and clinical reasoning)

A patient using topical timolol reports new wheeze and shortness of breath. What is the most appropriate action?

  1. Reassure that respiratory effects are unrelated to the drops
  2. Discontinue timolol and consider a topical carbonic anhydrase inhibitor Correct answer.
  3. Switch to topical latanoprost and double the timolol dose
  4. Continue timolol and add a bronchodilator

Explanation

Timolol is a non-selective beta-blocker that can be systemically absorbed and provoke bronchospasm, so it should be stopped in a patient with reactive airway symptoms. An alternative agent such as a topical carbonic anhydrase inhibitor avoids beta-blockade.

Question 7Written examination (optometry knowledge and clinical reasoning)

Which type of contact lens is generally best suited to correct irregular astigmatism from keratoconus?

  1. Scleral soft lens
  2. Soft toric lens
  3. Rigid gas-permeable corneal lens Correct answer.
  4. Soft spherical lens

Explanation

A rigid gas-permeable lens creates a tear lens that masks irregular corneal surface irregularity, restoring a smooth refracting surface. Soft lenses drape over the irregularity and therefore transmit much of the distortion.

Question 8Written examination (optometry knowledge and clinical reasoning)

Which colour vision defect is inherited in an X-linked recessive pattern?

  1. Blue-yellow acquired defect
  2. Protan deficiency Correct answer.
  3. Tritan deficiency
  4. Autosomal dominant achromatopsia

Explanation

Red-green defects, including protan and deutan types, are inherited in an X-linked recessive manner because the relevant opsin genes lie on the X chromosome, making males far more commonly affected. Tritan defects and most acquired dyschromatopsias follow different patterns.

Question 9Written examination (optometry knowledge and clinical reasoning)

A 55-year-old reports painless, gradual loss of central vision with distortion and a normal peripheral field. Which test is most likely to reveal the abnormality?

  1. Confrontation field testing
  2. Amsler grid testing Correct answer.
  3. Pupil light reflex testing
  4. Cover test

Explanation

Metamorphopsia with central visual loss suggests macular disease such as age-related macular degeneration, and the Amsler grid is designed to detect central distortion and scotomata. Peripheral field testing and alignment tests do not target macular function.

Question 10Written examination (optometry knowledge and clinical reasoning)

Which instrument principle underlies Goldmann applanation tonometry?

  1. Rebound of a probe from the cornea
  2. Force required to flatten a fixed area of cornea Correct answer.
  3. Resistance to indentation of the sclera
  4. Time taken for a puff of air to deform the cornea

Explanation

Goldmann tonometry measures the force needed to flatten a standard circular area of cornea, using the Imbert-Fick principle as applied to a calibrated tip. Corneal thickness and curvature can bias the reading.

Question 11Written examination (optometry knowledge and clinical reasoning)

A patient with long-standing diabetes reports sudden painless loss of vision with a large preretinal haemorrhage. Which process most likely explains this?

  1. Proliferative diabetic retinopathy Correct answer.
  2. Nuclear cataract
  3. Diabetic papillopathy
  4. Background diabetic maculopathy

Explanation

Proliferative diabetic retinopathy generates fragile new vessels that can bleed into the vitreous or preretinal space, causing sudden painless visual loss. Prompt referral is needed because of tractional and haemorrhagic risk.

Question 12Written examination (optometry knowledge and clinical reasoning)

Which finding best distinguishes a nuclear sclerotic cataract from a cortical cataract on slit-lamp examination?

  1. Peripheral wedge-shaped cortical water clefts
  2. A dense white capsular plaque
  3. Radial spoke-like opacities in the cortex
  4. Yellow-brown discolouration of the central lens nucleus Correct answer.

Explanation

Nuclear sclerosis produces a yellowish to brownish hardening and colour change of the central nucleus, often with increased refractive index. Cortical cataracts instead show radial or wedge-shaped opacities and water clefts in the cortex.

Question 13Written examination (optometry knowledge and clinical reasoning)

A patient has a painful red eye with a fluorescein-staining dendritic corneal lesion. Which management is most appropriate?

  1. Occlusive patching without referral
  2. Topical steroid alone
  3. Urgent referral for antiviral therapy Correct answer.
  4. Topical antibiotic and review in one week

Explanation

A dendritic ulcer indicates herpes simplex keratitis, which requires antiviral treatment and ophthalmological review because of risk of stromal involvement and scarring. Steroids alone can worsen active viral disease.

Question 14Written examination (optometry knowledge and clinical reasoning)

Which statement about the near triad is correct?

  1. It comprises accommodation, convergence, and pupillary dilation
  2. It comprises accommodation, convergence, and pupillary constriction Correct answer.
  3. It comprises accommodation, divergence, and pupillary dilation
  4. It comprises only accommodation and convergence

Explanation

The near response consists of accommodation, convergence, and miosis, all occurring together when fixation shifts to a near target. The coordinated triad optimises retinal image quality and binocular alignment at near.

Question 15Written examination (optometry knowledge and clinical reasoning)

A patient with a known pituitary tumour reports difficulty seeing objects on both sides of the face. Which explanation best fits this complaint?

  1. Occlusion of the central retinal artery
  2. Lesion of the temporal lobe
  3. Ischaemia of the optic nerve head
  4. Compression of decussating nasal fibres at the chiasm Correct answer.

Explanation

A pituitary mass expands upward and compresses the optic chiasm, damaging crossing nasal fibres and producing bitemporal field loss that impairs peripheral vision on both sides. This explains the patient's difficulty with objects to either side.

Question 16Written examination (optometry knowledge and clinical reasoning)

Which factor most increases the risk of a contact lens-related microbial keratitis?

  1. Use of daily disposable lenses
  2. Regular hand washing before handling
  3. Daily replacement of lenses
  4. Overnight wear of lenses Correct answer.

Explanation

Extended or overnight wear is the strongest modifiable risk factor for microbial keratitis because the closed eye reduces tear exchange and corneal oxygenation while allowing organisms to accumulate. Good hygiene and frequent lens replacement reduce risk.

Question 17Written examination (optometry knowledge and clinical reasoning)

A patient with early open-angle glaucoma has an intraocular pressure of 24 mmHg and a thin central cornea. How should corneal thickness influence interpretation?

  1. Corneal thickness has no effect on applanation readings
  2. Thin cornea only matters for rebound tonometry
  3. A thin cornea suggests true pressure may be overestimated
  4. A thin cornea suggests true pressure may be underestimated Correct answer.

Explanation

Applanation tonometry can underestimate true intraocular pressure in eyes with thin central corneas because less force is needed to flatten the cornea. This makes the measured 24 mmHg potentially higher in reality, increasing concern in glaucoma risk assessment.

Question 18Written examination (optometry knowledge and clinical reasoning)

Which refractive error is most consistent with an uncorrected eye that has clear distance vision but blurred near vision at age 45?

  1. Astigmatism
  2. Myopia
  3. Emmetropia with presbyopia Correct answer.
  4. Hyperopia with excess accommodation

Explanation

An emmetropic eye focuses distant objects clearly, but as accommodative amplitude declines with age, near focus becomes insufficient, producing presbyopic symptoms around the mid-forties. Distance acuity remains normal.

Question 19Written examination (optometry knowledge and clinical reasoning)

A patient presents with a sudden, painless, complete ptosis and a fixed dilated pupil. Which diagnosis must be excluded urgently?

  1. Myasthenia gravis
  2. Bell's palsy
  3. Third nerve palsy from a compressive lesion Correct answer.
  4. Horner syndrome

Explanation

A painful or painless third nerve palsy involving the pupil raises concern for a compressive lesion such as an aneurysm, which is a neurosurgical emergency. The combination of ptosis, a fixed dilated pupil, and motility deficit localises to the oculomotor nerve.

Question 20Written examination (optometry knowledge and clinical reasoning)

Which test is used to assess binocular single vision at near with a patient wearing their habitual correction?

  1. Ishihara plates
  2. Near cover test with prism neutralisation Correct answer.
  3. Schirmer test
  4. Amsler grid

Explanation

The cover test with prism neutralisation measures the magnitude and direction of a near deviation, allowing assessment of binocular alignment under habitual conditions. It directly evaluates motor fusion status at near.

Question 21Written examination (optometry knowledge and clinical reasoning)

A patient reports glare and haloes around lights at night with reduced contrast sensitivity but good Snellen acuity. Which condition is most likely?

  1. Early cataract Correct answer.
  2. Retinitis pigmentosa
  3. Macular hole
  4. Optic neuritis

Explanation

Lens opacification scatters light, producing glare and haloes particularly in dim illumination, and contrast sensitivity may fall before high-contrast Snellen acuity does. These symptoms fit early cataract formation.

Question 22Written examination (optometry knowledge and clinical reasoning)

Which property of a rigid gas-permeable lens material is most important for corneal health during daily wear?

  1. High water content
  2. Low modulus
  3. High oxygen permeability Correct answer.
  4. High surface wettability alone

Explanation

Rigid lens materials are not water-containing hydrogels, so oxygen transmission depends on the material's Dk, its oxygen permeability. Adequate oxygen flux to the cornea is essential to avoid hypoxic complications during daily wear.

Question 23Written examination (optometry knowledge and clinical reasoning)

A patient with type 2 diabetes has no retinopathy on dilated examination. What is the recommended general approach to follow-up?

  1. Immediate laser treatment of both eyes
  2. Annual screening only if HbA1c is normal
  3. No further screening until visual symptoms occur
  4. Regular dilated retinal screening at intervals based on risk Correct answer.

Explanation

Patients with diabetes but no retinopathy still require ongoing dilated retinal screening at guideline-defined intervals, because retinopathy can develop and progress before symptoms appear. Screening intervals are adjusted for risk factors and prior findings.

Question 24Written examination (optometry knowledge and clinical reasoning)

Which finding on a visual field test suggests a non-organic or unreliable response?

  1. Bitemporal hemianopia
  2. Arcuate scotoma
  3. Clover-leaf pattern respecting neither vertical nor horizontal midline Correct answer.
  4. Enlarged blind spot

Explanation

A clover-leaf or spiral field that does not respect known neural pathway boundaries suggests unreliable or non-organic testing. Genuine field defects usually respect the vertical or horizontal midline according to the anatomical lesion site.

Question 25Written examination (optometry knowledge and clinical reasoning)

Which mechanism best explains the reduced vision in amblyopia?

  1. Retinal detachment
  2. Diffuse corneal scarring
  3. Abnormal cortical visual development during the critical period Correct answer.
  4. Optic nerve demyelination

Explanation

Amblyopia results from abnormal visual experience during the sensitive period, disrupting cortical development of visual processing rather than causing structural eye disease. Treatment aims to restore balanced input before the critical period closes.

Question 26Written examination (optometry knowledge and clinical reasoning)

A patient has a spherical equivalent of -4.00 D and reports blurred distance vision without correction. Which optical correction is appropriate?

  1. A cylindrical lens only
  2. A concave (minus) lens Correct answer.
  3. A convex (plus) lens
  4. A plano lens

Explanation

A myopic eye has too much converging power relative to its axial length, so parallel light focuses in front of the retina. A diverging concave lens shifts the focal point back onto the retina. Convex lenses are used for hyperopia, cylindrical lenses correct astigmatism, and a plano lens has no power.

Question 27Written examination (optometry knowledge and clinical reasoning)

Which ocular structure has the highest refractive index in the normal eye?

  1. The vitreous humour
  2. The crystalline lens cortex
  3. The corneal stroma
  4. The crystalline lens nucleus Correct answer.

Explanation

The lens nucleus is the densest refractive element, with an index of about 1.41, higher than the cortex and cornea. The cornea and aqueous are around 1.376, and the vitreous is about 1.336. This gradient within the lens contributes to its total power.

Question 28Written examination (optometry knowledge and clinical reasoning)

Which extraocular muscle is primarily responsible for elevation of the eye when it is in the adducted position?

  1. Superior oblique
  2. Inferior rectus
  3. Superior rectus
  4. Inferior oblique Correct answer.

Explanation

In adduction the superior rectus acts mainly as a torsional muscle, whereas the inferior oblique's line of action aligns with elevation. The inferior oblique therefore becomes the principal elevator in the adducted position. This relationship is used clinically when testing individual muscles.

Question 29Written examination (optometry knowledge and clinical reasoning)

A patient reports transient visual obscurations lasting seconds, worse on bending forward. Which underlying mechanism is most likely?

  1. Accommodative spasm
  2. Retinal ischaemia from carotid disease
  3. Raised intracranial pressure with papilloedema Correct answer.
  4. Vitreous traction on the retina

Explanation

Brief bilateral obscurations provoked by posture change are a classic feature of papilloedema from raised intracranial pressure. Bending or straining transiently reduces perfusion to a swollen optic nerve head. Carotid disease typically causes amaurosis fugax lasting minutes, and vitreous traction causes flashes rather than obscurations.

Question 30Written examination (optometry knowledge and clinical reasoning)

Which finding on direct ophthalmoscopy indicates glaucomatous optic nerve damage?

  1. Cupping with thinning of the neuroretinal rim Correct answer.
  2. Spontaneous venous pulsation
  3. Swelling of the disc margins
  4. A pale disc with normal cupping

Explanation

Glaucomatous damage produces loss of retinal ganglion cell axons, which manifests as enlargement of the cup and thinning of the neuroretinal rim, often respecting the vertical poles. The cup-to-disc ratio increases and rim tissue is lost. Pallor without cupping suggests a non-glaucomatous optic neuropathy.

Question 31Written examination (optometry knowledge and clinical reasoning)

A patient with a painful red eye after sleeping in hydrogel lenses has a corneal infiltrate with an overlying epithelial defect. Which management is most appropriate?

  1. Continue lens wear and review in one week
  2. Prescribe a topical steroid alone
  3. Advise lubricants only and review in 48 hours
  4. Remove lenses and start intensive topical antibiotic therapy urgently Correct answer.

Explanation

A corneal infiltrate with epithelial defect in a contact lens wearer raises concern for microbial keratitis, especially with overnight hydrogel wear. Lenses should be removed and intensive broad-spectrum topical antibiotics started promptly, with same-day ophthalmological review. Steroids alone are contraindicated because they can worsen infection.

Question 32Written examination (optometry knowledge and clinical reasoning)

Which test is used to detect a relative afferent pupillary defect?

  1. The cover-uncover test
  2. The swinging flashlight test Correct answer.
  3. The Worth four-dot test
  4. The Maddox rod test

Explanation

The swinging flashlight test compares the direct response of each eye to light. A pupil that dilates when light swings to that eye indicates a relative afferent pupillary defect, reflecting asymmetric optic nerve or retinal disease. The other tests assess ocular alignment or binocular vision.

Question 33Written examination (optometry knowledge and clinical reasoning)

A patient with a long-standing esotropia suppresses one eye. Which adaptation is expected on the deviating eye?

  1. Development of a larger angle
  2. Enhanced colour discrimination
  3. Improved visual acuity
  4. Loss of binocular stereopsis Correct answer.

Explanation

Suppression eliminates the conflicting image from the deviating eye to avoid diplopia. Because the eyes are no longer aligned, stereopsis, which requires overlapping binocular input, is lost. Suppression may also lead to amblyopia rather than improved acuity.

Question 34Written examination (optometry knowledge and clinical reasoning)

Which type of age-related macular degeneration is characterised by choroidal neovascularisation?

  1. The dry atrophic form
  2. The reticular pseudodrusen form
  3. The neovascular (wet) form Correct answer.
  4. The peripheral drusen form

Explanation

Neovascular or wet AMD involves growth of abnormal choroidal vessels beneath the macula, which leak fluid and blood and cause rapid central vision loss. The dry form involves drusen and geographic atrophy without neovascularisation. Anti-VEGF therapy targets the neovascular form.

Question 35Written examination (optometry knowledge and clinical reasoning)

Which feature on a visual field printout most suggests a defect caused by a lesion anterior to the chiasm?

  1. A central scotoma respecting the horizontal midline
  2. A homonymous hemianopia
  3. A defect respecting the vertical midline and corresponding to the optic nerve Correct answer.
  4. A bitemporal hemianopia

Explanation

Pre-chiasmal lesions affect the optic nerve or retina and produce defects confined to one eye that respect the vertical midline. Chiasmal lesions produce bitemporal defects, and retrochiasmal lesions produce homonymous defects. Central scotomas respecting the horizontal midline are characteristic of retinal vascular or macular disease rather than optic nerve lesions.

Question 36Written examination (optometry knowledge and clinical reasoning)

Which clinical sign is most characteristic of keratoconus on retinoscopy?

  1. A bright red reflex
  2. A normal with-the-rule reflex
  3. A dull grey reflex
  4. A scissoring reflex Correct answer.

Explanation

Keratoconus produces irregular corneal astigmatism that causes the retinoscopic reflex to appear as a scissoring or split movement. This makes refraction difficult and is an early clinical clue. A bright red reflex is normal, and dull reflexes occur in media opacities.

Question 37Written examination (optometry knowledge and clinical reasoning)

A patient with a staphylococcal marginal ulcer has a painful red eye with a small peripheral infiltrate. Which feature distinguishes this from a sterile marginal infiltrate?

  1. An intact overlying epithelium with a quiet anterior chamber
  2. An epithelial defect with anterior chamber reaction Correct answer.
  3. Bilateral symptoms
  4. Presence of superficial punctate staining

Explanation

Marginal keratitis is typically a sterile hypersensitivity response to staphylococcal antigens, with an intact epithelium and minimal anterior chamber reaction. An epithelial defect with cells in the anterior chamber suggests infection and warrants antimicrobial treatment. The distinction guides whether steroids or antibiotics are appropriate.

Question 38Written examination (optometry knowledge and clinical reasoning)

Which finding indicates a carotid-cavernous fistula in a patient with a red eye?

  1. A dendritic corneal lesion
  2. A fixed constricted pupil
  3. A dilated, tortuous episcleral vessel with elevated intraocular pressure Correct answer.
  4. A sectoral iris atrophy

Explanation

A carotid-cavernous fistula raises episcleral venous pressure, producing arterialised, tortuous episcleral vessels and elevated intraocular pressure. It may also cause proptosis and a bruit. Dendritic lesions indicate herpes simplex, and a constricted pupil suggests Horner syndrome.

Question 39Written examination (optometry knowledge and clinical reasoning)

Which drug class is used topically to reduce aqueous production in glaucoma by blocking beta-adrenergic receptors?

  1. Carbonic anhydrase inhibitors
  2. Alpha-2 agonists
  3. Prostaglandin analogues
  4. Beta-blockers Correct answer.

Explanation

Topical beta-blockers such as timolol reduce aqueous humour production by blocking beta receptors on the ciliary epithelium. Prostaglandin analogues increase uveoscleral outflow, alpha-2 agonists both reduce production and increase outflow, and carbonic anhydrase inhibitors reduce production by enzyme inhibition.

Question 40Written examination (optometry knowledge and clinical reasoning)

A patient with acute anterior uveitis has photophobia and a miotic pupil. Which mechanism explains the miosis?

  1. Sympathetic denervation of the dilator
  2. Reduced aqueous production
  3. Parasympathetic overactivity from iris sphincter stimulation Correct answer.
  4. Mechanical stretching of the iris by synechiae

Explanation

Inflammation in anterior uveitis irritates the iris sphincter and ciliary body, producing a miotic pupil and photophobia. This is why cycloplegic drops relieve symptoms by relaxing the sphincter and ciliary muscle. Sympathetic denervation causes Horner syndrome, and synechiae may distort rather than dilate the pupil.

Question 41Written examination (optometry knowledge and clinical reasoning)

Which method is most appropriate for measuring visual acuity in a three-year-old child?

  1. Lea symbols or matching cards Correct answer.
  2. Amsler grid
  3. Ishihara colour plates
  4. Snellen letter chart at six metres

Explanation

Young children who cannot yet read letters are best assessed with symbol tests such as Lea symbols or matching cards, which use recognisable shapes. Snellen letters require letter knowledge, Ishihara plates test colour vision, and the Amsler grid tests central field. Age-appropriate testing improves reliability.

Question 42Written examination (optometry knowledge and clinical reasoning)

A patient has a total power of the eye of about 60 D, with the cornea contributing around 43 D. Which structure contributes most of the remaining power?

  1. The retina
  2. The vitreous
  3. The iris
  4. The crystalline lens Correct answer.

Explanation

The cornea provides roughly two-thirds of the eye's refractive power and the crystalline lens most of the remainder, about 19 to 20 D when unaccommodated. The vitreous, iris, and retina have little or no refractive power. This division is important when calculating intraocular lens power after cataract surgery.

Question 43Written examination (optometry knowledge and clinical reasoning)

Which condition is most strongly associated with a painful, deep, boring eye pain worse at night in an older adult?

  1. Giant cell arteritis Correct answer.
  2. Angle-closure glaucoma
  3. Dry eye disease
  4. Posterior scleritis

Explanation

Giant cell arteritis in older adults can cause severe headache, jaw claudication, and visual loss, and ocular ischaemia may produce deep pain. It is a medical emergency requiring urgent steroids and investigation. Dry eye causes irritation rather than boring night pain, and angle closure presents acutely with a red eye.

Question 44Written examination (optometry knowledge and clinical reasoning)

Which type of lens is used to neutralise a hyperopic refractive error in retinoscopy?

  1. A prism
  2. A concave lens
  3. A convex lens Correct answer.
  4. A cylindrical lens

Explanation

Hyperopia requires converging power, so a convex plus lens neutralises the with-movement reflex seen in retinoscopy. Concave lenses neutralise myopia, cylindrical lenses correct astigmatism, and prisms deviate light without changing vergence.

Question 45Written examination (optometry knowledge and clinical reasoning)

A patient wears a rigid gas-permeable lens that decentres superiorly. Which lens parameter adjustment is most likely to improve centration?

  1. Decrease the lens diameter
  2. Increase the optical zone
  3. Increase the lens diameter Correct answer.
  4. Increase the base curve radius

Explanation

A larger diameter increases lid interaction and helps hold the lens centred, reducing superior decentration. A flatter base curve may also improve fit. Decreasing the diameter reduces stability, and the optical zone affects optics rather than centration.

Question 46Written examination (optometry knowledge and clinical reasoning)

Which statement about the normal ageing changes of the crystalline lens is correct?

  1. The lens nucleus hardens and accommodative amplitude falls Correct answer.
  2. Lens elasticity increases with age
  3. The lens capsule thins markedly in all older adults
  4. The lens becomes more transparent with age

Explanation

With age the lens nucleus becomes denser and less elastic, reducing accommodative amplitude and producing presbyopia. Lens transparency also declines, contributing to cataract. The capsule does not uniformly thin in all older adults.

Question 47Written examination (optometry knowledge and clinical reasoning)

A patient reports a sudden onset of floaters and flashes with a curtain over part of the visual field. Which action is most appropriate?

  1. Perform a routine refraction
  2. Prescribe artificial tears
  3. Reassure and review in six months
  4. Arrange urgent dilated fundus examination Correct answer.

Explanation

Sudden floaters, flashes, and a visual field curtain suggest a posterior vitreous detachment with possible retinal tear or detachment. Urgent dilated fundus examination is required because a retinal detachment is sight-threatening and needs prompt treatment. Delay risks permanent visual loss.

Question 48Written examination (optometry knowledge and clinical reasoning)

Which factor most reduces the reliability of a visual field test?

  1. A refractive error corrected with glasses
  2. High fixation losses and false-positive responses Correct answer.
  3. Testing in the morning
  4. A small pupil of 3 mm

Explanation

High fixation losses indicate poor fixation, and frequent false-positive responses suggest the patient is pressing the button without seeing the stimulus. Both reduce test reliability and require caution when interpreting the field. A small pupil, corrected refractive error, and time of day have less influence on reliability indices.

Question 49Written examination (optometry knowledge and clinical reasoning)

A patient has a corneal foreign body with a rust ring after grinding metal. Which management is most appropriate?

  1. Prescribe a topical steroid alone
  2. Patch the eye without removal
  3. Prescribe lubricants and review in one week
  4. Remove the foreign body and rust ring under magnification and treat the epithelial defect Correct answer.

Explanation

A metallic foreign body with a rust ring should be removed under magnification, including the rust ring, to prevent inflammation and scarring. The resulting epithelial defect is then treated with antibiotic cover and review. Leaving the rust ring or patching without removal risks corneal damage.

Question 50Written examination (optometry knowledge and clinical reasoning)

Which property of the corneal endothelium is essential for maintaining corneal transparency?

  1. Its ability to regenerate rapidly after injury
  2. Its active fluid pump that keeps the stroma dehydrated Correct answer.
  3. Its production of aqueous humour
  4. Its pigmentation

Explanation

The corneal endothelium actively pumps fluid out of the stroma, keeping the cornea relatively dehydrated and transparent. Human endothelial cells have limited regenerative capacity, so loss of cells can lead to corneal oedema. The endothelium does not produce aqueous or contain pigment.