Weiss rings and blepharitis are two fairly common eye conditions, with the former affecting the inside of the eye and the latter causing inflammation of the eyelid.

What is a Weiss ring?

A Weiss ring is a type of 'floater'. These are pieces of debris that float around in the vitreous humor of the eye, which is the gel-like substance that sits inside the eyeball - between the lens and the retina. Floaters are often caused by shrinkage of the vitreous humor, causing tiny specks of collagen-like material to become visible as floating spots or threads in your field of vision. This is more common as you get older and is most noticeable when moving your eyes across a light background. A Weiss ring is a much larger, ring-shaped floater that is created by a posterior vitreous detachment (PVD) from around the optic nerve head. In other words, this is when the vitreous tissue detaches from the retina. Symptoms may include:

• One (most common) or multiple large floaters that are circular, ovoid or shaped in a bent line
• Random flashes of light across the field of vision - also known as photopsia

While a Weiss ring is usually harmless and will disappear on its own eventually, in a small number of cases a PVD can cause a retinal tear. These are vision threatening and so it is vital to consult with an eye specialist, or an optometrist immediately after developing a Weiss ring.

What is blepharitis?

If you suffer from frequently inflamed or swollen eyelids, you may have blepharitis. This chronic condition can range in severity, and although eyesight is rarely affected, vision problems can occur in the worst cases. While you should always consult an optometrist to accurately diagnose blepharitis, symptoms may include:

• Itchy or burning eyes
• Tearing
• Redness of the eyelids
• Red eye
• Flaky skin on the eyelids
• Crusting at the lid margins
• Dry eyes
• Foreign body sensation or grittiness
• Sensitivity to light      

Types of blepharitis

There are a number of different reasons for developing blepharitis, which can affect the symptoms you experience. People who have blepharitis caused by an infection may suffer a yellow- or green-coloured discharge that glues the eyelids together.Blepharitis resulting from an allergy may lead to darkened eyelids, although this is more common in children than adults. The condition can also be caused by dysfunctional meibomian glands, which lie just behind the eyelashes and produce oil to lubricate the eye.