When the tests disagree: glaucoma suspect with unreliable fields and a myopic OCT

The working diagnosis is glaucoma suspect, not definite glaucoma. The tests are discordant and several are unreliable.

• Visual fields: fixation losses of 4/6 and false positives of 25% exceed acceptable reliability limits. The scattered defects cannot be used to confirm glaucomatous loss. The field needs repeating with better technique.
• OCT: a red inferior sector is not diagnostic in a high myope with poor signal strength and marked peripapillary atrophy. Myopic tilt and peripapillary atrophy can cause segmentation error and false thinning. Signal strength of 6/10 is borderline and should be repeated.
• Optic discs: cup-to-disc ratios of 0.60 and 0.65 with inferior rim thinning are suspicious, especially with a family history, but are not specific. Disc size, rim width and any haemorrhage or notching matter.
• IOP and CCT: 22-23 mmHg is borderline, and a CCT of 540 microns is average. IOP alone does not diagnose glaucoma.
• Gonioscopy: open angles make angle-closure less likely but do not exclude open-angle glaucoma. The key judgement is to avoid starting lifelong drops on unreliable data while not dismissing a real risk.

I would arrange a structured repeat assessment rather than acting on a single inconsistent dataset.

• Repeat visual fields: at least two reliable 24-2 tests, with coaching on fixation and false positives, preferably on the same machine. Look for repeatable defects that respect the horizontal midline and match the disc.
• Repeat OCT: ensure good signal strength, check segmentation and compare with the optic disc photo. Interpret with caution because of high myopia and peripapillary atrophy.
• Optic disc imaging: stereoscopic disc photos or careful clinical drawing for baseline. Document rim thinning, notching, haemorrhage and vessel changes.
• IOP: repeat at different times of day and consider a diurnal curve.
• Pachymetry and gonioscopy: already done; repeat gonioscopy if there is any doubt.
• Referral: I would refer to ophthalmology if there is a repeatable field defect, progressive rim thinning, a disc haemorrhage, IOP rising into the high twenties, or if I cannot obtain reliable baseline testing. Given the family history and suspicious discs, a baseline ophthalmology opinion is reasonable even if the repeat tests are stable.
• Monitoring: if the risk is judged low after repeat testing, monitor with reliable fields, disc imaging and IOP every 6-12 months rather than starting treatment.

I would be honest but not alarming. I would say that his discs look suspicious and his family history matters, but the tests do not yet give a clear answer. The field test was unreliable because of fixation and false-positive responses, and the OCT scan is harder to interpret in a highly myopic eye with peripapillary atrophy. That does not mean the tests are useless; it means we need better-quality repeats before deciding about drops.

I would explain:

• glaucoma is a chronic optic nerve disease, and treatment is aimed at reducing risk of progression, not curing it;
• drops are generally lifelong and have side effects and cost, so we should not start them on uncertain evidence;
• the plan is repeat fields, repeat OCT and disc assessment, and review of the risks;
• if the repeat tests show definite damage or progression, referral and treatment will be recommended;
• if the tests remain stable and reliable, monitoring is appropriate;
• he should return sooner if he notices vision changes, and he should continue regular reviews.

I would check his understanding and give written information. The goal is a shared decision, not a false choice between 'you have glaucoma' and 'you are fine'.