Having astigmatism: definition, symptoms and correction
Key points Having astigmatism means having an eye whose cornea, and sometimes the lens, is not perfectly spherical:…
Mydriasis and miosis: why a pupil dilates or constricts
Mydriasis and miosis: why a pupil dilates or constricts Mydriasis refers to an abnormally dilated pupil, miosis to…
Eye anatomy: understanding how your vision works
Key points The eye works like a sophisticated camera: an optical system at the front focuses the light,…
Phosphenes: those flashes of light in the visual field
Key points A phosphene is a flash of light perceived without any real light, arising from mechanical or…
The diopter: definition, prescription and refractive surgery
Key points The diopter is the unit of optical power: it is the figure written on your spectacle…
The iris: anatomy, role, eye color and disorders
Key points The iris is the colored membrane of the eye, the anterior part of the uvea, located…
Visual acuity: definition, measurement and interpretation (20/20)
What does “10/10” actually mean? How visual acuity is measured, why it varies, and what it says (or doesn’t) about the true quality of your vision.
The crystalline lens: role, anatomy and ageing of the eye’s natural lens
The eye’s natural lens, the crystalline lens, handles focusing. Its role, its anatomy, and why it stiffens with age, leading to presbyopia and then cataract.
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