An Australian study found coffee and tea drinkers had significantly improved macular retinal nerve fibre layer thickness (mRNFL), a marker of neurodegeneration. 

Researchers led by Centre for Eye Research Australia’s Dr Lisa Zhu analysed the self-reported coffee and tea consumption data from 35,557 people in the UK’s Biobank, finding those who drank 2-3 daily cups of coffee benefitted most. Drinkers of more than four daily cups of tea also showed an increase in macular thickness, they said. 

Dr Zhu cautioned that they found drinking instant coffee or more than 2-3 cups of good-quality coffee may have negative health impacts and noted other studies have associated high caffeine consumption with glaucoma.