Glaucoma surgery vs eye drops – this has always been a dilemma for patients of glaucoma as well as the treating doctors. Medical management is usually the preferred first line of therapy for glaucoma and surgery is commonly reserved for patients who are resistant to medical therapy, intolerant of glaucoma medication or simply non-compliant.
However, there is ample evidence that a trabeculectomy (a gold standard for glaucoma surgery) performed early in the course of glaucoma has a greater chance of long-term success in terms of IOP control than one performed after years of medication, and additionally results in better preservation of visual fields than long-term medication or laser. Despite this, primary surgical management of glaucoma has not been widely adopted.
There are a number of reasons for this. The first is the general perception that long-term topical glaucoma therapy is simpler and safer than filtration surgery. A second is that many patients with glaucoma are asymptomatic and are naturally resistant to the concept of surgery before a course of medical treatment.
Finally we know that only around 23% of patients with glaucoma will eventually require surgery. A primary surgical approach would therefore be expected to lead to many unnecessary glaucoma surgeries, as judged by conventional measures.
Possible Adverse Effects of Glaucoma Surgery
Surgery may rarely cause potentially sight-threatening complications such as the possibility of unexpected dangerously low pressure or even surgery-related infection. However, much more commonly, filtration surgery causes refractive change and increased cataract formation.
Subsequent cataract surgery may compromise trabeculectomy function and a preexisting trabeculectomy may interfere with intraocular lens power calculations which is extremely important for a successful cataract surgery. These more common and less serious complications may have quite a profound negative effect on the perceived success of surgery in patients who have no preoperative visual symptoms.
Role of Medical Management of Glaucoma
The tendency toward primary medical management has probably increased with the advent of many new ocular hypotensive drugs such as topical carbonic anhydrase inhibitors (e.g. Dorzolamide and Brinzolamide), alpha-agonists (e.g. Brimonidine) and prostaglandin agonists (e.g. Latanoprost, Travoprost and Bimatoprost). Nevertheless there are a number of reasons why we should look again at primary surgery as a potential option in the management of our patients.
Medical therapy for glaucoma requires lifelong treatment. Long-term ß-blocker therapy (e.g. Timolol), the mainstay of glaucoma medical management, may be dangerous in even apparently healthy elderly patients. While ß-blocker therapy is contra-indicated in those with certain respiratory and cardio-vascular diseases, it is now evident that topical ß-blockers may produce significant sub-clinical respiratory impairment in otherwise normal elderly patients.
Many of the newer anti-glaucoma medications can be used instead of ß-blockers, but some are less effective in lowering the intraocular pressure and all have potential side effects, whether systemic or local. There are also significant cost implications in using the newer medications, most of which are expensive when compared with ß-blockers. In communities where operating theatre costs are low compared with long-term topical medication, glaucoma surgery as a first choice may provide significant cost savings.
How Medical Treatment Affects Success Rate of Glaucoma Surgery
A final consideration is the failure of filtration surgery to control the IOP in a proportion of patients. This failure rate is higher in patients who have had long-term medical therapy which induces alterations in the conjunctival cell population. In order to counteract this higher failure rate, we use anti-proliferative agents such as 5-Fluorouracil (5-FU) and Mitomycin C (MMC) perioperatively in patients who have had long-term exposure to topical anti-glaucoma medication.
A consequence of anti-proliferative (5-FU and MMC) use is a higher complication rate. Early postoperative hypotony (very low intraocular pressure), late bleb-leakage and bleb-related infection appear to be commoner after the use of anti-proliferative medication. There would clearly be a role for primary surgical management of glaucoma if it were to enable us to use less aggressive anti-proliferative therapy.
1. Glaucoma surgery is a relatively safe and successful option for primary management of patients with glaucoma.
2. Primary surgical management is not widely adopted because majority of the patients managed medically (on eye drops) will never require surgery and medical therapy is perceived to be safer.
3. When it comes to glaucoma surgery vs eye drops, treating doctors should identify which patients are suited better for glaucoma surgery and not for medical treatment.