Injecting a “gas bubble” into the eye is commonplace for certain types of retinal surgery. Not all retina surgery requires use of intraocular gas or air.
Vitrectomy is the basic operation performed by retina specialists. The vitrectomy is the removal of the vitreous, the watery-gel that fills most of the inside of the eye.
Removing the vitreous allows me to work on the retina; to repair macular holes, remove epiretinal membranes, fix retinal detachments, remove vitreous hemorrhage, etc.
It is my practice to use intraocular gas for repair of macular holes and retinal detachments. Almost without exception, these are the only two operations where I’ll use a gas as a tool to help me repair the retina.
Most retina specialists use a gas called C3F8. This is a very long acting gas and may remain in the eye for over a month. When used, most patients must assume a particular head position for several weeks to ensure that the “bubble” is correctly positioned inside the eye.
This is the origin of the famous “face down positioning.”
I prefer to use SF6. This is a smaller molecule and, depending upon the concentration used, will be absorbed by the eye much faster than its counterpart C3F8.
It is my observation over 23 years, that in most cases, the gas is needed for only a few days…not weeks. Not only is excessive head positioning avoided, but complications decrease, too.
I usually use SF6 for retinal detachments. Sometimes, too, just plain air.
Air is composed mainly of nitrogen and oxygen. These are much smaller molecules than either of the gases noted above; C3F8 or SF6. Hence, it makes sense that the smaller molecules are absorbed faster by the retina.
Many times, simply injecting air in the eye will give me a “gas bubble” that will help repair the retina, yet will be absorbed faster to reduce complications. The longer a gas stays in the eye, the higher the chance of complications such as causing retinal tears.
The faster absorption rate also means that while head positioning after surgery may be important, keeping your head in a fixed position for WEEKS is not necessary.
The chance of glaucoma developing with air is almost non-existent. Both C3F8 and SF6 have the capability of expanding in the eye when the gas is pure (i.e. not mixed with air). Most retina surgeons choose a gas mixture which expands very little or none at all. Thus, at times, very high eye pressure can develop when using these gases.
Air is non-expanding.
It is also possible that cataract formation after intraocular air may be reduced…this is just my observation, not gospel.
What Does this Mean?
Using simple air instead of the other gases in selected cases of retinal detachment and macular holes may prove to be just as effective, yet have fewer complications and without the agony of prolonged (unnecessary?) head positioning.