NZ Optometry Registration cheat sheet

Corneal layers (external to internal): epithelium, Bowman's layer, stroma, Descemet's membrane, endothelium; endothelial cells do not regenerate, so loss is permanent.

Aqueous outflow: trabecular meshwork to Schlemm's canal to collector channels to episcleral veins (conventional, ~80-90%); uveoscleral route is the remainder.

Retinal layers supplied by two circulations: inner retina by central retinal artery branches, outer retina (photoreceptors, RPE) by choriocapillaris.

Fovea has no inner retinal layers (foveal pit) and relies on choroidal supply; hence high acuity but vulnerability to vascular and toxic insult.

Lens transparency depends on ordered crystallin packing and relative dehydration; osmotic stress from sorbitol/polyol accumulation underlies diabetic and galactosaemic cataract.

Optic nerve head has no myelin anterior to the lamina cribrosa; myelination begins behind it, so demyelinating disease spares the intraocular nerve head.

Pathology patterns: oedema (intra/extracellular fluid), ischaemia (coagulative necrosis), inflammation (acute vs chronic infiltrate), and neoplasm (benign vs malignant, local vs metastatic).

Conjunctiva is highly vascular and lymphoid-rich; cornea is avascular and immune-privileged, which explains the corneal graft survival advantage and the absence of classic corneal inflammation signs.

Spherical equivalent = sphere + (cylinder / 2); used when a single power estimate is needed, e.g. for retinoscopy comparison or pre-operative planning.

Vergence formula: L = L' + F, where L is incident vergence (n/d), L' emergent vergence, F surface power; thin lens uses the same relationship.

Snellen acuity fraction: VA = test distance / distance at which the letter subtends 5 minutes of arc; 6/6 means 5 arcmin total letter, 1 arcmin stroke.

Jackson cross-cylinder: with handle at axis, it identifies astigmatism axis; with handle 45 degrees to axis, it refines cylinder power.

Duochrome (red-green) test exploits longitudinal chromatic aberration: red focuses behind, green in front; in myopia the red is clearer, in hyperopia the green.

Asthenopic symptoms with normal acuity suggest latent hyperopia; cycloplegic refraction (cyclopentolate or tropicamide) unmasks it, especially in children.

Anisometropia >1 D in children warrants correction and amblyopia surveillance; aniseikonia risk rises with spectacle correction of high anisometropia, favouring contact lenses.

Near point of convergence (NPC) normal is <=6 cm (break); receded NPC with exodeviation suggests convergence insufficiency.

AC/A ratio (heterophoria method) = (near deviation - distance deviation) / accommodative demand in dioptres; normal ~4-6 prism dioptres per dioptre.

Cover test interpretation: esophoria on alternate cover, exophoria on alternate cover; a tropia is seen on unilateral cover as the uncovered eye moves to take up fixation.

Amplitude of accommodation (push-up or minus lens) declines with age; Hofstetter's minimum = 15 - 0.25 x age, average = 18.5 - 0.3 x age.

Convergence insufficiency signs: exophoria greater at near than distance, reduced positive fusional vergence, receded NPC, symptoms with near work.

Accommodative insufficiency: reduced amplitude for age, normal AC/A, blurred near vision; distinguish from convergence insufficiency by NPC and phoria pattern.

Stereopsis thresholds: Titmus fly/animal ~3000-4000 arcsec, circles 400-40 arcsec, Randot similar; TNO uses random dot and requires no monocular cues, threshold to 15 arcsec.

Red flags for urgent referral: sudden painless vision loss (vascular occlusion, retinal detachment), painful red eye with decreased vision (keratitis, uveitis, acute angle closure), and trauma.

Acute angle closure: mid-dilated fixed pupil, corneal oedema, shallow anterior chamber, IOP often >40 mmHg; urgent IOP lowering and referral for laser peripheral iridotomy.

Bacterial keratitis: contact lens wear, corneal infiltrate with overlying epithelial defect; culture if severe or contact lens-related, treat with fluoroquinolone and refer.

Diabetic retinopathy grading: mild/moderate/severe non-proliferative (microaneurysms, haemorrhages, hard exudates, IRMA) and proliferative (NVD/NVE); refer for laser or anti-VEGF.

Age-related macular degeneration: dry (drusen, RPE atrophy) vs wet (choroidal neovascularisation, subretinal fluid/haemorrhage); wet needs urgent referral for anti-VEGF.

Glaucoma: optic disc cupping (CDR >0.6, asymmetry >0.2), neuroretinal rim thinning, RNFL defect; IOP is a risk factor, not a diagnostic criterion alone.

Retinal detachment: flashes, floaters, curtain, visual field defect; fundus shows elevated retina with corrugated folds; urgent referral for repair.

Dk/t is the oxygen transmissibility; for daily wear, Dk/t >=24 and for extended wear >=87 (units 10^-9 cm mL O2 / s mL mmHg) are common minimum benchmarks.

Base curve selection: steeper lens = tighter fit; fluorescein pattern shows central pooling with steep fit, central bearing with flat fit.

Scleral lens fitting: vault over cornea, landing zone on sclera, fluid reservoir; assess with OCT or slit lamp and check for conjunctival compression.

Keratoconus: rigid gas-permeable lenses or sclerals; avoid soft toric lenses unless mild; monitor for corneal hydrops and apical scarring.

Contact lens-related microbial keratitis risk rises with overnight wear, poor hygiene, and smoking; advise daily disposable or strict care regimen.

Presbyopic contact lens options: multifocal soft (centre-near or centre-distance), translating RGP, or monovision; assess binocular summation and contrast sensitivity.

Orthokeratology: overnight rigid lens reshapes corneal epithelium; requires baseline topography, regular follow-up, and vigilance for microbial keratitis.

Topical anaesthetic (proparacaine, oxybuprocaine): rapid onset, short duration; for tonometry and foreign body removal only, not for chronic pain.

Mydriatics vs cycloplegics: phenylephrine is a mydriatic (alpha-1), tropicamide and cyclopentolate are cycloplegic (antimuscarinic); atropine is longest-acting cycloplegic.

Topical beta-blockers (timolol) reduce IOP by decreasing aqueous production; contraindicated in asthma, heart block, and bradycardia.

Prostaglandin analogues (latanoprost) increase uveoscleral outflow; side effects include iris darkening, eyelash growth, and periorbital fat atrophy.

Topical corticosteroids (prednisolone, dexamethasone) suppress inflammation; monitor for IOP rise, cataract, and infection; taper to avoid rebound.

Antibiotic choice: fluoroquinolones (ciprofloxacin, ofloxacin) for bacterial keratitis; chloramphenicol for conjunctivitis; avoid aminoglycosides in epithelial defect due to toxicity.

Prescribing in New Zealand: optometrists with therapeutic endorsement may prescribe scheduled medicines; check scope of practice and standing orders.

Amblyopia critical period: visual development to ~7-9 years; treat with occlusion or atropine penalisation, plus refractive correction.

Leukocoria (white pupillary reflex) differential: retinoblastoma, congenital cataract, Coats disease, persistent fetal vasculature; urgent referral.

Strabismus in children: congenital esotropia needs early surgery; accommodative esotropia managed with hyperopic correction and amblyopia therapy.

Retinoscopy in children: use cycloplegia (cyclopentolate 1%) to relax accommodation; retinoscopy is the primary objective refraction method.

Low vision aids: magnifiers (handheld, stand), telescopes (distance), electronic video magnifiers; magnification = reference acuity / required acuity.

Visual acuity in preverbal children: preferential looking (Teller cards), optokinetic nystagmus, and fix-and-follow; compare with age norms.

Colour vision testing: Ishihara for red-green defects; Farnsworth-Munsell for acquired defects; important for occupational screening.

Diabetes: diabetic retinopathy, macular oedema, cataract, and cranial nerve palsies; HbA1c control reduces progression; screen annually.

Hypertension: arteriolar narrowing, AV nicking, flame haemorrhages, cotton wool spots (malignant hypertension); refer if grade III/IV.

Thyroid eye disease: proptosis, lid retraction, restrictive myopathy; monitor for optic neuropathy (colour vision, visual fields).

Giant cell arteritis: >50 years, headache, jaw claudication, visual loss; urgent ESR/CRP and high-dose steroids to prevent bilateral blindness.

Multiple sclerosis: optic neuritis (pain on movement, RAPD, colour desaturation); MRI and neurology referral.

Sarcoidosis: granulomatous uveitis, conjunctival nodules, lacrimal gland enlargement; chest X-ray and serum ACE.

HIV: CMV retinitis (CD4 <50), cotton wool spots, Kaposi sarcoma; refer for systemic management.

Visual acuity: Snellen or logMAR at 6 m; pinhole improves refractive error but not media or retinal causes.

Slit lamp: diffuse, direct focal, indirect, retroillumination, and sclerotic scatter; use optic section to assess corneal depth.

Goldmann applanation tonometry: 3.06 mm diameter applanated area; calibrate, use fluorescein, avoid in corneal oedema or irregular surface.

Pachymetry: central corneal thickness affects IOP reading; thin corneas underestimate IOP, thick overestimate.

Gonioscopy: Shaffer grading (0-4); identify angle structures (Schwalbe's line, trabecular meshwork, scleral spur, ciliary body band).

OCT: retinal nerve fibre layer and macular thickness; useful for glaucoma and macular disease monitoring.

Visual field: Humphrey 24-2 or 30-2; reliability indices (fixation losses, false positives/negatives) must be checked.

Optometrists are regulated under the Health Practitioners Competence Assurance Act 2003 (HPCA Act); the Optometrists and Dispensing Opticians Board (ODOB) sets standards.

Annual practising certificate (APC) requires continuing professional development (CPD) and compliance with ODOB recertification requirements.

Informed consent: patient must understand procedure, risks, benefits, and alternatives; document consent, especially for invasive or research procedures.

Privacy Act 2020 and Health Information Privacy Code: patient records are confidential; disclose only with consent or legal obligation.

Referral obligations: refer when condition exceeds scope of practice; keep records and communicate findings to the patient and referrer.

Cultural safety: recognise the impact of the practitioner's own culture and bias on care; Te Tiriti o Waitangi principles (partnership, participation, protection) guide practice.

Advertising and professional conduct: no misleading claims; maintain professional boundaries and declare conflicts of interest.

Cultural safety in New Zealand: acknowledge Māori as tangata whenua; use Te Tiriti principles to guide equitable care and engagement with whānau.

Health literacy: use plain language, teach-back, and visual aids; confirm understanding rather than assuming.

Shared decision-making: present options with risks and benefits, elicit patient values, and document the agreed plan.

Interpreter use: for limited English proficiency, use professional interpreters rather than family members, especially for consent.

Breaking bad news: use a structured approach (e.g., SPIKES) with privacy, empathy, and clear next steps.

Patient-centred communication: open-ended questions, active listening, and addressing emotional concerns alongside clinical findings.

Equity: recognise barriers (cost, transport, disability, rurality) and offer solutions such as telehealth or community outreach.

Cultural safety in New Zealand: acknowledge Māori as tangata whenua; use Te Tiriti principles to guide equitable care and engagement with whānau.

Health literacy: use plain language, teach-back, and visual aids; confirm understanding rather than assuming.

Shared decision-making: present options with risks and benefits, elicit patient values, and document the agreed plan.

Interpreter use: for limited English proficiency, use professional interpreters rather than family members, especially for consent.

Breaking bad news: use a structured approach (e.g., SPIKES) with privacy, empathy, and clear next steps.

Patient-centred communication: open-ended questions, active listening, and addressing emotional concerns alongside clinical findings.

Equity: recognise barriers (cost, transport, disability, rurality) and offer solutions such as telehealth or community outreach.