Visual Disorders, Glasses, Contact Lenses and Eye Surgery

Q1 — Sample Band 6 response (8 marks), annotated

LASIK is highly effective for myopia correction: 94% of the myopia group achieved 6/6 uncorrected vision at 12 months, with only 6% requiring residual glasses. For hyperopia the effectiveness is lower but still substantial: 81% achieved 6/6, with 19% needing a residual correction. The difference between groups suggests that LASIK is more precise and reliable for myopia than for hyperopia at these prescription ranges. [2 marks — interprets both groups with cited figures and comparison]

Limitation 1 — Dry eye: 22% of the myopia group and 31% of the hyperopia group reported dry eye symptoms at 12 months. LASIK involves cutting a corneal flap, which severs corneal nerves that regulate tear production and blinking reflex; reduced neural input leads to decreased tear secretion and evaporative tear loss. Dry eye can cause discomfort, fluctuating vision, and — in severe cases — reduced quality of life despite technically successful surgery. [1 mark]

Limitation 2 — Residual correction / undercorrection: 19% of hyperopia patients still needed glasses after surgery. LASIK permanently removes corneal tissue; the correction cannot be added back. Undercorrection in hyperopia is more common because the ablation pattern for steepening the peripheral cornea is harder to calibrate precisely. While a second “enhancement” procedure may be possible, it is limited by remaining corneal thickness. [1 mark]

Reading glasses in the ≥40 subgroup: 38–41% of patients aged 40 and over required reading glasses by 12 months. This is explained by presbyopia, not by surgical failure. LASIK reshapes the cornea — it corrects the fixed curvature that was causing refractive error. However, it has no effect on the crystalline lens, which hardens and loses elasticity with age (presbyopia). In the mid-40s, the ciliary muscles contract but the sclerotic lens cannot increase its curvature to accommodate for near objects. LASIK patients over 40 will develop presbyopia just as those without surgery do; reading glasses provide the extra convergence the stiff lens can no longer supply. [2 marks — identifies presbyopia; explains lens sclerosis and accommodation failure]

Evidence-based judgement: The data most strongly support LASIK for adults under 40 with myopia of −1 to −9 D, stable prescription, adequate corneal thickness, and no significant dry eye. In this profile: 94% achieve 6/6, patient satisfaction is 91/100, and the individual is unlikely to require reading glasses within the surgical benefit period. LASIK’s lifestyle advantage over glasses (no device management, suitability for sport and water) and over contacts (no daily hygiene compliance, no infection risk) is maximised in younger myopic patients meeting all eligibility criteria. [2 marks — specific patient profile; justified against data and lesson evaluation framework]

Marking criteria:

• 2 marks — Interprets effectiveness data for both myopia and hyperopia groups, citing specific figures and comparing outcomes between groups.
• 1 mark — Identifies and explains Limitation 1 (dry eye: mechanism of nerve damage, tear reduction, clinical significance).
• 1 mark — Identifies and explains Limitation 2 (residual correction / undercorrection: irreversibility, higher rate in hyperopia, limited options post-surgery).
• 2 marks — Explains reading glasses requirement using presbyopia biology (lens sclerosis → accommodation failure → inability to focus near objects; LASIK corrects cornea, not lens; universal ageing process).
• 2 marks — Reaches a specific, evidence-based judgement naming the patient profile most favoured by the data, with justification from the table and lesson evaluation criteria.

Q2 — Sample Band 6 response (7 marks), annotated

Effectiveness in correcting −4.50 D myopia means moving the focal point of parallel light from distant objects from its current position in front of Marcus’s retina to land precisely on the fovea, enabling 6/6 uncorrected (or equivalent corrected) distance vision. [1 mark — defines effectiveness in context]

Mechanism: Spectacles place a −4.50 D concave lens ~12 mm from the eye; this diverges parallel light and moves the focal point back to the retina. Daily disposable contact lenses sit on the tear film overlying the cornea, applying the same optical correction but with better peripheral coverage and less frame obstruction. LASIK permanently flattens the central cornea using an excimer laser, removing the excess convergence and repositioning the focal point without any external device. All three are fully effective at −4.50 D if properly specified. [1 mark — mechanism of all three]

Risk — Marcus’s occupational context: Daily disposables in dusty, wet conditions carry a high risk of corneal keratitis (infection); particles trapped under the lens damage the epithelium, and pool/ocean water introduces microorganisms. Glasses break or fog in fieldwork. LASIK eliminates the need for any external device, and once healed carries no ongoing ocular risk related to the surgery itself. [1 mark — occupational risk comparison, all three referenced]

Reversibility: Spectacles and contacts are fully reversible (remove to return to uncorrected state); LASIK is irreversible. If Marcus’s prescription changes after surgery (unlikely at 32 with an 8-year stable history, but possible), he may require enhancement limited by remaining corneal thickness or return to glasses. [0.5 mark]

Cost: Daily disposables ~$500/year (within budget, ongoing); glasses ~$300–$500 every 2 years. LASIK for bilateral surgery ~$5,600–$7,000 (within his stated budget, one-off). Over 20+ years, LASIK is cost-neutral or favourable versus contacts. [0.5 mark]

Dry eye concern: Mild dry eye is listed as a LASIK contraindication in severe cases. Marcus has mild seasonal dry eye managed with lubricating drops. Mild dry eye does not absolutely rule out LASIK, but it means: (a) LASIK may worsen dry eye symptoms temporarily (corneal nerve sectioning during flap creation reduces tear reflex), and (b) he should be evaluated carefully by a refractive surgeon to assess whether his dry eye severity crosses the threshold for exclusion. If managed and documented as mild, LASIK is not automatically disqualifying. [1 mark — specific contraindication identified; assessed as not automatically disqualifying with monitoring]

Justified recommendation: LASIK is the most contextually appropriate technology for Marcus, given his occupational demands (dusty/underwater environments preclude contacts and make glasses impractical), his stable prescription, adequate corneal thickness, and budget. The irreversibility must be acknowledged and accepted through informed consent. A prerequisite is formal ophthalmological assessment confirming that his dry eye is sufficiently mild not to be a contraindication, and that he understands the elevated risk of dry eye symptoms post-surgery. If LASIK is assessed as contraindicated, daily disposable lenses with sealed goggle protection during training are the next-best alternative. Spectacles alone are least appropriate given his duties. This recommendation is contextually specific — it does not imply LASIK is universally superior. [2 marks — contextually appropriate, non-one-winner recommendation with conditions; acknowledges irreversibility and dry eye risk]

Marking criteria:

• 1 mark — Defines effectiveness in context of correcting −4.50 D myopia (focal point repositioned onto retina).
• 1 mark — Correctly explains mechanism of all three technologies.
• 1 mark — Compares risk in Marcus’s specific occupational context (dusty/underwater → contacts high-risk; glasses impractical; LASIK avoids ongoing device-related risk).
• 0.5 mark — Compares reversibility (glasses/contacts reversible; LASIK irreversible).
• 0.5 mark — Compares cost in context of Marcus’s budget.
• 1 mark — Identifies dry eye as a specific LASIK concern; correctly assesses that mild dry eye does not automatically disqualify but requires assessment; notes that LASIK may worsen symptoms temporarily.
• 2 marks — Reaches a justified, contextually appropriate recommendation for Marcus (LASIK favoured with conditions), does not claim it is universally best, provides a fallback if contraindicated, uses lesson evaluation criteria throughout.