Early surgical intervention has been advocated by the European glaucoma community. This approach was initially supported by a study from Scotland that compared initial medical therapy with initial surgical therapy for newly diagnosed POAG (25). In this study, 116 patients were randomized to either trabeculectomy at diagnosis or initial medical therapy followed by trabeculectomy in unsuccessful cases. No difference in visual acuity was detected, but greater visual field loss was found in patients with initial medical therapy. The investigators suggested that this was due to delay of surgery, whereas medical therapy was modified in patients with minimal visual field loss at diagnosis.
The Moorfields Primary Treatment Trial also evaluated medical therapy vs. surgical therapy for the primary treatment of glaucoma. This study randomized 48 patients to initial surgery and 40 patients to initial medical therapy. Surgery as primary treatment resulted in a lower mean IOP than medicine as primary treatment, although the visual fields were not statistically different (26). The investigators suggested that initial surgery is a safe and more cost-effective method for treating glaucoma.
CIGTS evaluated initial medical therapy vs. initial surgical therapy for the primary treatment of glaucoma (6,16). In that study, the surgical group achieved a lower average IOP than the medical group, but there was no statistically significant difference in the visual field scores between the two groups. As well, the medical treatment group had a better average visual acuity than the surgical group, and was less likely to have a clinically substantial visual loss (15 letters or more). This was partially due to the surgical group having a cataract extraction rate almost three times higher than the medical group. However, the difference remained even after adjusting for cataracts. The investigators speculated that the differences in the results of this study compared with the European studies might be related to having patients with glaucoma earlier in the disease course, as well as the availability of newer, more effective medical treatments. They did not suggest changing current treatment protocols based on their 5 year results indicating that longer-term studies were required for a chronic diseases such as glaucoma.
These studies suggest that both medical and surgical therapies as initial treatment for glaucoma are effective and safe. In general, surgery results in a slightly lower IOP than medical treatment alone. However, the importance of this additional IOP lowering in early glaucoma must be considered in relation to potential complications and effect on central vision. Since the potential for vision threatening complications is real, we feel surgical treatment should still be reserved for second- or third-line therapy until conclusive evidence becomes available to show that surgical treatment of glaucoma results in better visual function outcomes. The exception to this rule is in developing countries, where early surgical intervention is often indicated. With limited health care resources, there is often limited access to long-term follow-up care. In addition, life-long medical treatment is commonly prohibitively expensive for the patient. Under these circumstances, primary surgical treatment for glaucoma is a cost-effective solution despite the increased potential for complications (14,15).
