The three thieves of sight

Diminishing vision may be a factor of ageing but it’s important to understand the three main causes of sight loss and the treatments available.

Woman with her eyes covered

It’s important to understand three of the most common conditions to affect your vision – cataracts, glaucoma and age-related macular degeneration – and recognise how the three thieves of sight are treated, prevented and managed.

As we age, diminishing vision is one of the greatest threats to our quality of life. The three most common conditions that cause sight loss, do so and are treated in different ways:

  • Blindness caused by cataracts is reversible with surgery
  • Blindness caused by glaucoma is permanent but your remaining vision can be preserved
  • Blindness caused by age-related macular degeneration (AMD) can be treated in some cases and may improve your vision.

Cataract, which is a clouding of the natural lens of the eye, is the biggest cause of reversible blindness worldwide, affecting 133 million people.

Early signs of cataract

  • Blurry vision
  • Glare from car headlights
  • Difficulty reading

In fact, people who wear glasses may notice their prescription changing in a short space of time. For some, their prescription is affected so much that they can often read without spectacles, something they've not been able to do for years. This is the phenomenon of 'second sight', but it's not everlasting.

Untreated, cataracts will cloud your vision until there's little left.

Treating cataracts

Of all the conditions that will make you go blind, we know the most about cataract. Early cataract surgery involved extensive wounds in the eye which often required periods of immobility. Even today, some patients imagine that cataract surgery involves removing the eye from its socket and placing it on the cheek. The truth is far less gruesome than that. We now combine micro-incision surgery with foldable lenses and phacoemulsification so you don't have to wait to go effectively blind before we can treat you, and we can achieve fantastic results.


Sometimes referred to as 'the silent thief of sight', glaucoma often develops with no pain and no symptoms until it is very advanced. Once glaucoma has affected vision, there's no going back. Glaucoma often runs in families so it's particularly important to have regular eye health checks if you have a family history.

All types of glaucoma affect the optic nerve which conveys signals from the eye to the brain. The nerve is made up of over 1.2 million nerve fibres. With glaucoma, bundles of these nerves start to die and gradually cause loss of your peripheral, navigating vision.

Mature women with glasses

Treating glaucoma

We're not sure exactly what causes glaucoma, but we do know that we can slow down the disease by lowering the eye pressure. This can be achieved using eye drops, laser treatment, surgery or a combination of these methods.

When caught early, glaucoma can be treated and controlled. The best we can hope for is to preserve the sight you have left but sometimes the disease is aggressive and all we can do is slow it down.

Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the most common reason behind blind registration in the UK. In AMD there is death of light-sensitive receptors in the retina.

Signs of AMD

  • Distortion
  • Blurred vision
  • Affects central vision, blocking out the things you're trying to focus on but doesn't affect peripheral vision so you won't go completely blind.

AMD risk factors

The chance of you having AMD is greatly increased by:

  • Age
  • Smoking
  • Family history (30x more likely to have AMD if it has affected one of your parents).

Treating wet and dry AMD

Dry AMD is caused by a build-up of breakdown products from dying cells in the retina. There's nothing that can be done to treat it, but it progresses very slowly. Wet AMD, where bleeding occurs on the retina, progresses rapidly. Its development can be slowed, but not stopped, by injecting drugs into the eye every 4-6 weeks. If caught early, this may preserve your sight enough to continue activities like driving.

How to lower your risk of eye disease

We can't prevent these diseases from happening, but there are things you can do to lower your risk of developing them:

  • Have regular eye health checks to catch conditions early
  • Don't smoke
  • Wear sunglasses to protect your eyes from harmful UV radiation emitted from the sun
  • Maintain a healthy diet that includes plenty of green, leafy vegetables.

Humma Shahid, Consultant Ophthalmologist, Nuffield Health

Last modified: November 17, 2020

Written by 3:18 pm Health