A truck driver who wants 'the strongest prescription'

The pinhole is the key result. A pinhole that does not improve acuity means defocus is not the limiting factor: light is being blocked, scattered or misperceived. Pushing more minus into the trial frame changes the position of the focal point but cannot fix that, and it may blur him further by adding unnecessary accommodative demand.

Before I attribute everything to the cataract:

• Repeat acuity under good illumination with the correct chart distance and a properly centred, adequately sized pinhole - a mis-sized or decentred pinhole gives false negatives.
• Do glare or photostress testing, which often exposes posterior subcapsular opacity more than Snellen acuity does.
• Dilate and examine the fundus properly; a hazy view is not a normal fundus. Document the limits of the view and consider referral for a dilated assessment or imaging if the macula cannot be seen.
• Recheck the pupils after dilation, confirm there is no afferent defect, and compare with any previous records to judge the rate of change.
• Ask about amblyopia and old prescriptions - without history you cannot assume the left eye was ever 6/6.

Conclusion: the left acuity is most likely media-related, but 'most likely' is not 'certain', and my report to his employer must say what I measured, not what I assumed.

What I will document: acuity monocular and binocular, with and without correction; the refraction and what it achieves; the slit-lamp findings including the posterior subcapsular change; glare sensitivity; the limits of the fundus view; and the referral for cataract assessment.

What I will refuse:

• To issue a prescription engineered to meet a standard rather than to correct his refractive error.
• To certify fitness beyond what my findings support, or to omit the cataract from a form.
• To sign a statement that implies he meets a commercial standard when he demonstrably does not.

How I frame it to him: 'I'll fill in the form accurately and send it. The fitness decision isn't mine - the licensing authority's medical review makes it, using what I record. If I wrote something I couldn't stand behind, it would put you and everyone else on the road at risk, and it would come apart the first time it was audited.'

Note that commercial standards are typically stricter than private ones, and that a report he disagrees with can be reviewed through the authority's process. Document his request and my decline, and note that I advised him not to drive if he cannot meet the standard until the assessment is complete.

Today: prescribe the subjective refraction that gives the best binocular balance, not the maximum minus. Right eye −1.25 DS to 6/6; the left eye takes whatever gives the best obtainable acuity without disturbing binocular balance. Keep the add, and consider a separate pair optimised for night driving with a clean, anti-reflective lens and good contrast.

Discuss surgery as a plan, not a threat:

• He is symptomatic and likely to be a good surgical candidate; the posterior subcapsular change may progress faster than the nuclear component.
• Monovision is generally a poor choice for a commercial driver - reduced contrast and stereopsis at night are exactly the conditions in which he works. Say so plainly if he raises it.
• A toric intraocular lens is worth discussing if he has 1.00–1.25 D or more of regular corneal astigmatism; otherwise a standard monofocal is reasonable.
• Warn him that the final spectacle prescription is generally not issued until at least four weeks after surgery, and that acuity may not return to normal if there is underlying macular change or if the left eye has long-standing amblyopia.
• Make clear that I cannot guarantee a particular post-operative acuity, and that the licensing authority will need current measurements afterwards.