Sub-macular haemorrhage is a technical term for a blood blister in the area of sharp central vision. It blurs vision and creates a dark purple patch because it prevents the retina working normally.
The blood causes irreversible damage because it triggers scar tissue formation in the most delicate area of sight leaving permanent damage. Sub-macular blood blisters can be slipped away from central vision using the buoyant effect of a gas bubble floating inside the eye. To do this, the eye is made numb with local anaesthetic and sterile with antiseptic before a gas bubble is injected into the eye cavity. This gas bubble expands over approximately 24 hour period and looking down directly over the bubble helps slip the blood away from central vision.
Usually, tissue plasminogen activator, a naturally occurring agent that dissolves blood clots is injected to help soften the blood clot so that it is easier for the gas bubble to displace it. The blood is usually displaced within 24 hours.
The procedure is painless and very low risk. The major potential problems are an infection being introduced into the eye at the time of the injection, or a tear in the retina which could cause a retinal detachment. Both of these complications occur at less than 1% frequency.
After the injection, the eye is covered with a sterile pad to protect it until the local anaesthetic wears off. Patients go home after the injection and do not have to do anything until an hour or two before going to bed. They then look down to the floor while sitting and bend forward to ensure that the line of sight is directly over the bubble. There is no need to position sooner in the day because the gas bubble will be too small to be effective. It is important however, not to lie flat on your back which could concentrate the drug near the area of sharp central vision and potentially cause damage.
After the local anaesthetic wears off, some people feel a scratchy sensation due to the irritation of the eye surface but this is usually trivial. The eye might be bloodshot. The eyesight usually improves noticeably over several days and then more gradually for number of weeks afterwards.
There is no restriction on daily activity after the first 24 hours although it is not safe to fly in an aircraft until the gas bubble has dissipated (usually over 7-10 days).
The return in vision is variable as it depends on the underlying cause of the haemorrhage. If the cause of the haemorrhage is due to wet AMD, either Eylea or Lucentis is also injected during the procedure to control the unstable blood vessels.
If you have any particular questions please don’t hesitate to ask me prior to or after the procedure.
Instructions After Pneumatic Displacement Of Submacular Blood
- You may take the eye pad off after 1-2 hours.
- Use the lubricating eye drops as needed for comfort.
- There will also be a small packet with some local anaesthetic. Use this if the eye is very painful.
- 1-2 hours prior to going to bed sit down and lean forward so that you can look vertically down to your heels. This will place the gas bubble in the line of sight. It is critical to look vertically not partly forward.
- Spend as much time as possible the following day looking down taking necessary breaks naturally. The more time you spend the day after the injection looking face down, the more the blood will clear.
- Call the office during working hours if you have continuing pain or deterioration in the vision.