Myopic Choroidal Neovascularisation (mCNV)

Myopic Choroidal Neovascularisation (mCNV) is a complication of high (pathological) short-sightedness where abnormal blood vessels grow beneath the retina, usually affecting the macula (the central part of the retina responsible for detailed vision).

Common symptoms

Blurred central vision, Distorted vision where straight lines appear bent or wavy, A grey dark or missing patch in the centre of vision, Difficulty reading, Difficulty recognising faces, Colours appearing less clear or washed out

Description

Myopic Choroidal Neovascularisation (mCNV) is an eye condition that can develop in people with high or pathological myopia (severe short-sightedness). In highly myopic eyes, the eyeball is longer than normal, which causes the retina and the tissues beneath it to become stretched and thinner over time.

As these tissues weaken, abnormal new blood vessels can grow underneath the retina, particularly beneath the macula – the part of the eye responsible for sharp, detailed central vision. These blood vessels are fragile and may leak fluid or bleed, damaging the macula and causing sudden changes in vision.

People with mCNV often notice symptoms such as blurred central vision, straight lines appearing bent or wavy, difficulty reading, problems recognising faces, or a dark or missing patch in the centre of their vision. Peripheral (side) vision is usually unaffected, so many people are still able to move around independently even though detailed tasks become more difficult.

The condition is usually diagnosed by an ophthalmologist using a retinal examination and imaging such as Optical Coherence Tomography (OCT). In some cases, additional scans using a special dye may be performed to identify leaking blood vessels.

The main treatment for mCNV is a series of anti-VEGF injections, such as ranibizumab (Lucentis) or aflibercept (Eylea), which are injected directly into the eye. These medicines help stop the abnormal blood vessels from growing and leaking, reducing the risk of further damage to the retina. Unlike some other retinal conditions, many people with mCNV only require a small number of injections before the condition becomes inactive, although regular monitoring is important as it can sometimes return.

The outlook for people with mCNV has improved significantly with modern treatments. Many people retain useful vision, particularly when treatment begins quickly. However, some may be left with permanent central vision loss or distortion if scarring develops in the macula. Good lighting, magnification, larger text and accessible technology can all help people adapt if their vision has been affected.