Jalali L, Allahveisie A, Rezaei S, et al
Contact your GP or optometrist promptly if you experience: Sudden vision changes , including blurred vision, floaters (dark spots or strings), or flashes of light Progressive difficulty reading or recognising faces Dark or empty areas in your visual field Distorted vision , where straight lines appear wavy Eye pain or redness accompanied by vision changes Difficulty with night vision or colour perception If you experience sudden, painless vision loss in one or both eyes, this constitutes an ophthalmological emergency
That uncertainty is a meaningful risk and a key reason health regulators advise against unprescribed use
[DOI] [PubMed] [Google Scholar] 85.Gasbjerg L.S., Helsted M.M., Hartmann B., Jensen M.H., Gabe M.B.N., Sparre-Ulrich A.H., Veedfald S., Stensen S., Lanng A.R., Bergmann N.C., et al