What is a “Macular Hole”?
The “macula” is the centre of the retina where the highest visual acuity is obtained. A macular hole is a full thickness defect in this important location of the retina. It is equivalent to a hole in the centre of the film in a camera. This hole is as a result of traction of the vitreous on the retina. The vitreous is a jell-like substance which fills the central cavity of the eye. As you age, the vitreous undergoes changes and “shrinks”. When it does this, it can pull on the centre of the macula and create a full-thickness defect. There is no actual loss of tissue in the hole. Visual acuity decreases markedly depending on the size of the hole. This is due to disruption of the normal physiologic arrangement of the photoreceptors (light sensing cells) in the centre of the macula, and due to collection of fluid under the retina in this area.
What can be done for a macular hole?
A surgical procedure is performed which involves removing the vitreous gel and internal limiting membrane (the innermost layer of the retina) to relieve the traction on the macula. When the traction is relieved, the macula can “relax” back to its normal anatomical position which closes the hole.
The vitreous gel is replaced with a mixture of air and a slowly dissolving inert gas at the end of your surgery. The surface tension of the gas bubble acts to aid in closure of the macular hole. There are two types of gas: one lasts for 2 weeks and the other 2 months, depending on the length of tamponade required your macular hole. In order to maximize the effect of the bubble, you may be requested to maintain face down (prone) positioning or positioning on your side for a period of time after the surgery. This ensures that the gas bubble with stay in contact against the macular hole.
What can I expect after surgery?
Gas placed within the eye will be gradually reabsorbed by the eye during a 2-8 week period following surgery. As the bubble is reabsorbed, the vitreous cavity refills with a fluid that is naturally produced in the eye. Vision will be markedly reduced after the surgery as you cannot see well through the bubble. As the bubble reabsorbs you will gradually see more and more. You should not expect a significant improvement in your vision until at least 6 weeks after the surgery. The maximum improvement will be noticed between 6 weeks and 3 months after the surgery, and vision may continue to improve for up to 2 years as the retina remodels itself.
You may not fly in an airplane or travel to high elevations (i.e. mountains) until the bubble is completely gone. Some types of general anaesthetic agents must be avoided (nitrous oxide or laughing gas) while there is a bubble in your eye.
There is usually very little pain following the operation. It is common to experience mild irritation for a few days after the surgery. You will be given an eye shield which should be worn while sleeping for the first week. You will be given a prescription for some light painkillers to be used for 3 days, and eye drops to be used for 4 weeks. Severe pain or nausea and vomiting are indications to call in immediately, even if it is the evening or weekend. It may be an indication that the pressure in the eye is too high. The eyelids are usually swollen for the first couple of weeks, but this gradually resolves. As the gas bubble shrinks in your eye, you will begin to notice a fluid level when looking through the operated eye. This level will gradually change over time. Often, satellite bubbles form, giving the appearance of fish eggs of small balloons when you look through the operated eye. This is normal and no cause for alarm.
What are the risks of the procedure?
There is always a risk associated with a surgical procedure. A retinal detachment may occur in 1-3% of patients but is usually treatable with further surgery, often with little or no adverse effect on your final vision. The intraocular pressure is transiently elevated in about 20% of patients. Often a feeling of nausea or eye pain will accompany elevated intraocular pressure. This is usually temporary and is well-controlled with eye drops. However, the inconvenience of additional office visits or medical therapies may be necessary.
Severe complications occur infrequently: the risk of severe haemorrhage, infection, irreparable retinal detachment or complications from anaesthesia occur in approximately one in several thousand cases. These complications could result in irreversible blindness. Rarely vision or eyelid droop may develop and need to be repaired with further surgery.
The most common side effect of macular hole surgery is cataract development. A cataract is a side effect of vitrectomy surgery, regardless of the underlying diagnosis. It begins to develop in almost all patients by 6 to 12 months after surgery; however, it may develop sooner. If necessary, it can be surgically removed in the future or in the same sitting and an intraocular lens can be implanted.
The risks of the procedure are far outweighed by the benefits to your vision by repairing the macular hole. Up to 15% of patients may develop a macular hole in the other eye, or suffer vision loss in the other eye from some other cause. Therefore, repair of the macular hole is very important.
What follow-up is necessary?
For the benefit of the patient, it is important to monitor the status of the eye following surgery. You will usually be seen on day one, at 1 to 2 weeks, at 6 to 8 weeks, and then three or four months after surgery. These follow-up dates may be modified. You will be given written directions after surgery about the care of your eye and follow-up appointments.
If you experience pain or significant decrease in vision after the surgery please call 021 671 5154. During office hours, our friendly staff will tend to your call, and after hours there will be an answering machine message with a cell phone number for you to call.