This video describes vitrectomy in the context of diabetic retinopathy. It is generally, but not specifically indicative of the procedure appropriate to the other conditions listed below.
What is the Vitreous?
The vitreous is an inert jelly that occupies the space between the lens and the retina at the back of the eye. It forms the largest space in terms of volume in the eye. Sometimes it is of distinct therapeutic benefit to remove the vitreous jelly.
This discussion will be confined to what is called pars plana vitrectomy – whereby access is obtained by instrumentation inserted into the vitreous cavity via the scleral coat of the eye. Vitrectomy is sometimes performed via the front of the eye, through a cataract incision when there is the complication of vitreous loss during cataract surgery.
Why do we do a vitrectomy?
- Diabetes and complications
- Retinal Detachment
- Complications from cataract surgery
- Macular surgery
- Endophthalmitis (severe internal infection of the eye)
- Choroidal tumours
What is involved?
Improvements in terms of instrumentation, microscopes and viewing systems made this sort of surgery possible from the mid ‘70s onwards – many years behind lens surgery.
Access is obtained by making three “ports” through the visible portion of the sclera. One is a fluid pipe to maintain inflation of the globe, which would otherwise collapse as the vitreous is removed. The other port is used for a light pipe to illuminate the back of the eye, and the third port is for the vitreous cutting device and other surgical instruments such as scissors, diathermy cautery devices and retinal lasers. These days the size of the ports can be as little as the needle used to give a ‘flu jab! – and the wounds are self sealing and stitchless.
Once the vitrectomy (removal of the vitreous jelly) has been completed, surgery is performed within the back of the eye according to the indication (see above). Sometimes this may involve removal of a foreign body or dislocated lens fragment. Sometimes a retinal detachment will require fluid drainage, or a macula will require the peeling and removal of a membrane. There is a wide range of procedures that can be performed within the eye. Fluids called perfluorocarbon “heavy liquid” are sometimes inserted to flatten the retina in place allowing laser to be applied to help stick the retina back in place. These cannot be left in the eye, and must be replaced with silicone oil or a gas.
These images (top) show the effects of the vitreous jelly pulling on the macula – a process called Vitreomacular Traction Syndrome. The macula becomes thickened and swollen, with resultant loss of vision. The images (bottom) show the effect of removal of the vitreous. The macula has returned to normal thickness with an improvement in central vision.
What happens after surgery?
Once surgery has been completed the vitreous cavity must be replaced with either a liquid or a gas. Frequently an inert gas is placed in the eye so that it can be used to tamponade or press against a break or tear in the retina, whilst the effects of laser come into play – forming adhesions and preventing re-detachment. You may be asked to posture whilst the gas is in the eye, so that the gas actually covers the area requiring tamponade. The gas may remain present in the eye, diminishing in size for a period of up to 5 weeks. You will notice this bubble in the eye, and vision will improve once the bubble is no longer sitting in front of the central vision.
If you have had gas inserted into the eye you will not be able to fly in a pressurized aircraft, as the gas could expand with sight threatening (and painful) complications.
Complex retinal detachments sometimes require the insertion of silicone oil. This may be left in the eye, or subsequently removed at a later date.
What are the potential complications?
- Retinal breaks and further detachment – necessitating further surgery
- Haemorrhage – often clears, may require further surgery
- Raised pressure and glaucoma – usually managed with drops
- Cataract – almost all eyes will require cataract surgery in the years following vitrectomy
- Corneal decompensation – may require corneal grafting
- Soft eye (Hypotony)
- Endophthalmitis (infection)– may require further surgery