Like a camera, the eye needs to focus the beams of light reflecting off objects onto the back of the retina. The majority of the focusing is done by the cornea, and the ciliary muscles of the lens provide fine tuning. If the light is focused too early, we cannot see long distances clearly, and this is termed myopia, or short-sightedness. There are many causes of blurred vision:
Causes of Blurred Vision
- Use of atropine or other anticholinergics
- Presbyopia -- Difficulty focusing on objects that are close. Common in the elderly as Accommodation tends to decrease with age.)
- Cataracts -- Cloudiness in the eye's lens, causing poor night-time vision, halos around lights, and sensitivity to glare. Daytime vision is eventually affected.
- Glaucoma -- Increased pressure in the eye, causing poor night vision, blind spots, and loss of vision to either side. A major cause of blindness. Glaucoma can happen gradually or suddenly—if sudden, it is a medical emergency.
- Diabetic retinopathy -- This complication of diabetes can lead to bleeding into the retina. Another common cause of blindness.
- Macular degeneration -- Loss of central vision, blurred vision while reading, distorted vision (like seeing wavy lines), and faded, washed-out colours.
- Eye infection, inflammation, or injury.
- Floaters -- Tiny particles drifting across the eye. Although often brief and harmless, they may be a sign of retinal detachment.
- Retinal detachment -- Symptoms include floaters, flashes of light across your visual field, or a sensation of a shade or curtain hanging on one side of your visual field.
- Optic neuritis -- Inflammation of the optic nerve from infection or multiple sclerosis. You may have pain when you move your eye or touch it through the eyelid.
- Stroke or Transient ischemic attack
- Brain tumours
- Bleeding into the eye
- Temporal arteritis -- Inflammation of an artery in the brain that supplies blood to the optic nerve.
- Migraine headaches -- Spots of light, halos, or zigzag patterns are common symptoms prior to the start of the headache. An ophthalmic migraine is when you have only visual symptoms without a headache.
- Pregnancy – the hormones that cause water retention can also cause the eye to hold more fluid, changing the focal distance. However, it can also be a sign of pre-eclampsia, so make sure your obstetrician is aware of the symptom.