TIGER: Surgical Trial

Research details

  • Type of funding: Other
  • Grant Holder: Professor Tim Jackson
  • Institute: King's College London
  • Region: London
  • Start date: September 2020
  • End Date: August 2025
  • Priority: Treatment
  • Eye Category: AMD

Vitrectomy, subretinal Tissue plasminogen activator and Intravitreal Gas for submacular haemorrhage secondary to Exudative age-Related macular degeneration (TIGER): a European randomised controlled surgical trial.

Brief Lay Background

Age-related macular degeneration (AMD), causes loss of central vision as a result of damage to the macula – a small area of the retina, the light-sensitive tissue at the back of the eye.

AMD is the most common cause of permanent and severe sight loss in the UK, affecting around 600,000 people. This figure is expected to more than double by 2050.

What problem/knowledge gap does it help address

Wet AMD is caused by the growth of abnormal blood vessels in the retina which can leak blood or fluids, causing damage to the macula. Treatment with anti-VEGF drugs, which are delivered through injections into the back of the eye, can help to stop abnormal blood vessel growth and leakage – helping to preserve central vision in many people with wet AMD.

But in some patients, the fragile blood vessels bleed into the eye, causing a large clot called a submacular haemorrhage (SMH). Blood is toxic to the light-sensing cells in the retina – so when it finally clears, it leaves behind permanent scarring and a severe worsening of vision.

There is a surgical procedure to clear SMH that involves injecting a ‘clot-busting’ drug into the clot to dissolve it. While this approach offers the potential to improve vision compared to anti-VEGF injections alone, it also has downsides. The patient will need to lie still with their head facing downward for five days after the procedure – and there is also a risk of complications, some of which could lead to loss of vision or further surgery.

Aim of the research project

To carry out a large clinical trial to find out if surgery is more likely to improve vision than standard treatment with anti-VEGF injections alone for patients with SMH due to wet AMD.

Key procedures/objectives
  1. Recruit 210 people with SMH due to wet AMD – one half will be randomly allocated to receive surgery and anti-VEGF injections, and the other will receive anti-VEGF injections alone.
  2. All study participants will receive eye injections monthly for the first three injections, then every two months for a year in total. At each visit, they will have their sight tested, a routine scan of the inside of their eye, and a eye examination with a doctor.
  3. They will also undergo more extensive assessments at the beginning, middle and end of the study – including testing their reading and distance vision, a quality of life questionnaire, and specialised photographs to assess the health of their eye.
  4. At the end of the study, the researchers will compare data between the groups to look for differences in the safety and effectiveness of these treatments. One of the most important measures will be if there is a meaningful improvement in central vision in patients who had surgery. 
Potential impact on people with sight loss

This trial could lead to changes in clinical practice for the treatment of patients with SMH due to wet AMD.

If the results show that surgery and anti-VEGF injections are better at improving vision than anti-VEGF injections alone, it could lead to patients being offered this treatment combination in the future. But if it is not, patients can be spared the risk, discomfort and inconvenience of undergoing a surgical procedure that is unlikely to improve their vision.

Finally, the results may also provide evidence that anti-VEGF injections are safe and effective for this group of patients, which could help widen access to this treatment.