Once the decision to proceed with glaucoma surgery has been made, several factors should be considered during surgical planning.
1. Patient Age
Younger patients tend to have a more vigorous healing response making them more susceptible to failure. This may indicate the use of antifibrotic agents, although they should be used with caution in young myopes due to the risk of hypotonous maculopathy. By the virtue of their longer life expectancy, younger patients are more likely to have surgical failure within their lifetimes, requiring repeat surgery. We therefore advise initial surgery in one upper quadrant leaving the other quadrant for repeat surgery at a later date. It is important to remember that surgery in younger patients may result in an increased risk of blebitis and endophthalmitis due to their longer life expectancy. Older patients may have a decreased healing response and may be more susceptible to complications in the short-term. In addition, elderly patients may have difficulty with postoperative care without assistance from caregivers.
2. External Disease
Evidence of ocular surface disease, including dry eye, conjunctival scarring, symblepharon, and previous ocular surgery, should be noted. These conditions make the surgical procedure more difficult, and also increase the risk of postoperative scarring, and complications. Lack of suitable conjunctiva may require an alteration in both the type and the site of surgery planned (e.g., from a trabeculectomy to a seton).
The lids should always be examined for epiphora, entropion, or distachiasis. These should be dealt with prior to glaucoma surgery. Temporary measures, such as Quickert sutures for entropion or epilation for distachiasis, may be sufficient. Chronic infections, such as staphylococcal blepharitis or purulent discharge from the lacrimal sac, must be addressed prior to glaucoma surgery.
3. General Health Status
Although most glaucoma surgery is performed with local anesthetic, including topical anesthetic, general health status should be known. In particular, patients with cardiovascular disease, systemic hypertension and diabetes are at increased risk of suprachoroidal hemorrhage. Surgery should be performed with caution in such cases. Patients with liver dysfunction or patients on anticoagulation therapy will have increased intraoperative bleeding. Such patients should be advised of the increased risk and be assessed by the relevant specialists before recommending discontinuation of anticoagulation therapy. Most glaucoma surgery can be successfully performed with patients on anticoagulation therapy but informed consent is important in such cases.
