Why is gas necessary for macular hole surgery?

How does a macular hole affect patient vision?

A macular hole affects the central part of the retina. Using an example of the retina working like the film in a camera, a macular hole causes a hole or distorted patch in the centre of the developed picture. Patients have problems with tasks dependent on central vision such as reading or driving.

Surgical repair of macular holes can close this hole in over 90% of cases. This operation requires a vitrectomy that removes the vitreous scaffold that is thought to contribute to the formation of the hole. Before this operation was reported in the 1980s, the majority of macular holes were incurable. Advances over the years include peeling of the innermost layer of the retina around the macular hole to encourage the hole to close and the use of gas bubbles inside the eye.

Why do we use a gas bubble in macular hole surgery?

There are different theories about why it helps. All these theories are based on the the fact that the gas floats on the natural fluid present inside the eye, like a balloon filled with helium gas rises upwards. This is why there is such emphasis placed on adopting a face down position after macular hole surgery: the gas will float upwards to naturally press against the macular hole. Some ophthalmologists believe that this upward pressure helps push the hole close. Others think that by pushing against the hole, the gas bubble prevents the natural fluid from keeping the hole open. Finally, another group of vitreoretinal surgeons suspect the bubble acts as a support that allows healing factors to pull the hole closed.

The true answer as to why the gas bubble helps may be a combination of all three theories.

What are the risks of using a gas bubble in macular hole surgery?

There are downsides to using the gas bubble. The vision is poor while the gas is present. I advise against driving with a gas bubble as it may cause troublesome and distracting reflections. There are situations where the gas bubble can expand and cause a loss of vision: with certain types of general anaesthesia, flying in an aircraft or experiencing high altitudes.

The gas bubble is naturally absorbed by the eye and different gases are present for various lengths of time, some lasting up to 8 weeks. I use a short-acting gas that should be completely absorbed within 2-3 weeks, allowing you to resume normal activities as soon as possible.