Filtering glaucoma surgery involves creating a new drainage channel with the use surgical tools. When medications and laser surgery does not successfully lower eye pressure, or the pressure begins to rise again, the doctor may recommend filtering surgery.
In filtering surgery, a partial thickness flap is lifted in the sclera (the white part of the eye) and a tiny drainage hole is made to the anterior chamber of the eye. An implant called Ex-press shunt can be placed under this flap or the flap can be sutured after creation of the drainage channel. The new drainage channel allows fluid to flow out of the anterior chamber to the subconjunctival area and helps lower eye pressure. This prevents or reduces damage to the optic nerve.
This procedure is usually done under local anesthesia which involves injection of local anesthetic around the eye. Often a limited type of anesthesia, called intravenous (I.V.) sedation, is used. This injection is not painful when topical anesthesia with eyedrops and I.V. sedation are used first. The patient doesn’t experience any pain during surgery.
Filtrating surgery is highly successful. However intraocular pressure may be too low or too high in the early postoperative period. This may necessitate medical, surgical interventions or laser suturelysis. If needed, surgery can be done a number of times in the same eye. The most important factor that cause failure of the surgery is fibrosis in the new drainage area. To overcome this risk we use antifibrotic drugs, such as mitomycin-C and 5-FU during or after surgery.
Usually, filtering surgery is an outpatient procedure, requiring no overnight hospital stay. The following day and with regular intervals after surgery your eye doctor will check your eyes. The doctor will also look for any signs of infection or increase in inflammation.
For at least one week after surgery, patients are advised to keep water out of the eye. Most daily activities can be done, however, it is important to avoid driving, reading for long time, bending, and doing any heavy lifting.
