الفهرس 
Anatomy of the Angle and Physiology of Aqueous Formation & OutflowOnly 14 pages are availabe for public view
 |  | from | 178 |  |  |
| | | from | 178 | | |
Abstract
The success of filtration surgery depends greatly on the early recognition and appropriate management of postoperative complications.
Although the list of potential complications following filtration surgery is extensive, a short differential can be obtained by firstly differentiating whether the anterior chamber, either is formed or shallow/flat. Secondly is the intraocular pressure is elevated or low and finally assessing the filtration bleb whether formed or flat.
Using this systematic approach, complications during the early postoperative period are easy to diagnose.
A flat or formed AC with low IOP strongly suggests either a wound leak or overfiltration. In some cases, this may be further complicated by aqueous hyposecretion.
If Hypotony is left untreated, vision threatening complications may result, including: Hypotony Maculopathy, Choroidal Effusions, Endophthalmitis and Suprachoroidal Hemorrhage.
As a rule, treatment of hypotony within a few weeks is recommended to either prevent the development of maculopathy, or allow its resolution with an excellent chance of retaining or restoring vision. Therapy is best aimed at the underlying cause of the hypotony. The bleb should be repaired if leaking, or revised if overfiltering.
When surgical intervention is required to reconstruct the leaking bleb, both advancement of adjacent conjunctiva or free conjunctival autograft are the standard surgeries.
Preserved human amniotic membrane transplantation, is a new option for the repair of intractable leaking bleb or in cases where the eyes underwent previous surgeries.
Suprachoroidal Hemorrhage is a devastating complication most commonly seen following glaucoma filtering surgery. It can occur both intraoperatively and postoperatively. Intraoperatively, the prompt identification of a suprachoroidal hemorrhage is of hallmark importance. Failure to identify this in time can lead to expulsion of the intraocular contents.
Treatment of postoperative suprachoroidal hemorrhage is directed toward control of the IOP and relief of pain. Most of these eyes do well with conservative management, and surgical drainage usually is not necessary.
Malignant Glaucoma following filtration surgery remains one of the most challenging complications in terms of diagnosis and management faced by glaucoma surgeons but now fortunately the configuration of anterior segment structures can be assessed by using UBM, or by slit-lamp adapted optical coherence tomography a new non invasive high resolution imaging technique that may be helpful in recognizing the early stages of malignant glaucoma by objectively monitoring anterior chamber depth.
Medical treatment is effective in 50% of the cases. In cases refractory to medical and laser treatments, one of the surgical approaches should be tried next keeping in mind that Pars plana vitrectomy is the preferred surgical technique.
In the case of a formed anterior chamber and elevated intraocular pressure, the bleb status will narrow the differential.
If the bleb is elevated the most likely diagnosis is an encysted bleb. Another possibility is that the bleb is formed with something other than aqueous.
If the bleb is flat, then aqueous is not flowing through the trabeculectomy either because the scleral-flap sutures are too tight or there is a physical blockage to filtration, such as blood, iris, or vitreous in the osteium which is excluded by Gonioscopy.
When managing if the osteium is clear, then digital ocular massage will usually establish the flow of aqueous around the flap edges and lower the IOP. If ocular massage is unsuccessful, then suture lysis or release is the next step. More recently Adjustable Suture is used allowing a more gradual titration of the IOP.
Since Carins and Watson introduced trabeculectomy in 1968, the success of this procedure has hinged on the development of a functioning filtering bleb, which is in turn influenced by a number of factors including postoperative wound healing properties, surgical techniques, and use of antimetabolites .
Excessive postoperative scarring at the level of the conjunctiva and sclerostomy sites is associated with poor postoperative pressure control but the use of mictomycin-C and 5-fluorouracil have led to a dramatic improvement in trabeculectomy success rates.
Although the increase of the success using mictomycin-C and 5-fluorouracil they have also caused thinner blebs that are more likely to leak and become infected. It’s clear that there is a need for novel agents in glaucoma surgery that can decrease fibroblast proliferation while not leading to extreme thinning of conjunctival tissue, as anti-vascular endothelial growth factor (anti -VEGF) compound.
Early postoperative complications such as early wound leak, flat AC, and suprachoroidal hemorrhage are associated with an increased incidence of bleb-related infections.
As blebitis may be a precursor to endophthalmitis, aggressive antibiotic treatment at this early stage of the infection is recommended to prevent progression to endophthalmitis.
It is very important to differentiate between blebitis, which is considered a “localized bleb infection” without involvement of intraocular contents, and the more serious bleb associated endophthalmitis as the treatment and prognosis for these two entities are different.
DS a safe surgical procedure to reduce IOPs its Complication rate appears to be lower; flat anterior chamber, hypotonic maculopathy, and postoperative infections are rare. It can be offered at an earlier stage of the disease and even be considered a first line therapy when medical or laser treatment is insufficient or unavailable.
The efficacy of non penetrating procedures perceived to be inferior compared to trabeculectomy. However, a number of adjunctive techniques are now being used that have been shown to increase efficacy. These include the intraoperative use of antimetabolites, the use of implants to maintain the intrascleral space as well as performing laser goniopuncture early when the IOP rises above the target value.