The Baltimore eye study determined the need for more screening methods to detect glaucoma. In the 1991 Baltimore eye study, researchers found that tonometry, optic nerve assessments, and medical history did not provide a reasonable balance of sensitivity and specificity to adequately screen a person for glaucoma.
Key Points:
Overall, the Baltimore eye study is a landmark study because it showed that population-based glaucoma screening programs could not rely on tonometry alone to determine a person’s disease status. The effectiveness of past techniques was limited and new approaches to glaucoma screenings were encouraged.
A study for the AGES! In the AGIS study, 789 eyes with medically recalcitrant open-angle glaucoma (OAG) were randomized to two different treatment sequences: argon laser trabeculoplasty --> trabeculectomy --> trabeculectomy (ATT; n=404) and trabeculectomy --> argon laser trabeculoplasty --> trabeculectomy (TAT; n=385). The primary outcomes include visual field (VF) & visual acuity (VA), and other outcomes included intraocular pressure (IOP), surgical complications, time to treatment failure, additional medical therapy needed.
Key Points:
Overall, the AGIS study is a landmark study because it studied varying sequences of surgical and procedural interventions in glaucoma patients. The key conclusion at the time surrounded the different optimal treatment algorithm for white and black patients. However, given the development of treatment options such as SLT and MIGS since the study, the outcomes of the study should be considered in the context of the times of the study.
Nowadays we can’t imagine a world without lasers in glaucoma!Published in 1990, the Glaucoma Laser Trial (GLT) sought to determine the safety and efficacy of Argon Laser Trabeculoplasty (ALT) compared to topical medications (timolol drops) as first-line treatment of primary open-angle glaucoma (POAG). In this multicenter RCT from the early 1990s, 271 patients were included, and the two eyes of each patient were randomized into two groups: ALT first (LF, n = 271) or timolol maleate 5% first (MF, n = 271).
Key Points:
GLT is a landmark study that challenged the traditional paradigm of maximizing medical therapy before utilizing laser treatment. This study found ALT to be effective and safe in patients with POAG and comparable to medical therapy overall. However, despite these findings, ALT was rarely used as a first-line therapy due to the adoption of more effective glaucoma medications (prostaglandin analogues) and due its risk of trabecular meshwork scarring over multiple treatments. ALT paved the way for the introduction of newer forms of laser trabeculoplasty, such as selective laser trabeculoplasty (SLT).
No pressure… but we may need to lower the pressure. Prior to the CNTGS, there was no consensus regarding the treatment of normal tension glaucoma – glaucomatous optic nerve damage in the setting of normal range intraocular pressures (IOP). In this 1998 study, patients with normal tension glaucoma were randomized into a treatment cohort (pressure lowered by >30%) and an untreated, control cohort to determine if lowering IOP played a protective role in patients with normal tension glaucoma.
Key Points
Overall, the CNTGS is a landmark study because it highlights the role of pressure-lowering therapy in preventing disease progression of normal tension glaucoma. Importantly, the visual field benefits were only identified once excluding patients for visual changes secondary to cataract formation. Still, the clinical relevance of the CNTGS showed that treating IOP, even in patients with normal IOP, reduces glaucomatous visual field damage in patients with NTG.
An ounce of eye drops might be worth a pound of prevention. In the 2002 OHTS trial, subjects with ocular hypertension (but not glaucoma) were randomized to observation or to topical treatment to reduce IOP by 20% and to <24 mmHg. Subjects were monitored for the development of glaucoma.
Key Points:
Overall, the landmark OHTS trial showed that treating ocular hypertension reduced the risk of developing POAG by more than half. Clinicians should consider treatment in ocular hypertensive patients with moderate to high risk of developing glaucoma.
In the 2003 Early Manifest Glaucoma Trial (EMGT) study, 255 patients with open-angle glaucoma (OAG) were randomized to argon laser trabeculoplasty (ALT) with topical betaxolol (n=129) or no immediate treatment (n=126) and had follow up appointments every three months for four years.
Key Points:
Overall, the EMGT study is a landmark study because it quantitatively concluded that initial IOP reduction is crucial in lowering the risk of progression in early OAG and that the magnitude of immediate IOP reduction postoperatively predicted disease progression.
Is there a plumber in the house? The TVT study sought to compare the safety and efficacy of tube shunt surgery to trabeculectomy with mitomycin C (MMC) in eyes with prior intraocular surgery. Patients aged 18-85 years old with intraocular pressure (IOP) ≥ 18 mm Hg and ≤ 40 mm Hg on maximum tolerated medical therapy, and who had previously undergone cataract surgery and/or failed filtering glaucoma surgery were randomized into 2 groups: the 350 mm Baerveldt implant group (n = 107) and the trabeculectomy with MMC group (n = 105).
Key Points:
TVT is a landmark study in changing practice patterns to expand tube implantation in cases beyond refractory glaucoma. This study demonstrated that tube implantation is more efficacious in lowering IOP in patients who failed previously filtration surgery, rather than undergoing a repeat trabeculectomy.
The horizon may be out of sight, but thanks to the HORIZON trial, a brighter future for glaucoma patients is now in sight. Combined glaucoma and cataract surgery has become increasingly common in North America with the introduction of minimally invasive glaucoma surgery devices and techniques. The HORIZON trial compared clinical outcomes of patients following cataract surgery with (n=369) and without a Hydrus Microstent (n=187)
Key Points:
Overall, the HORIZON landmark study demonstrated that use of a Schlemm's canal microstent in addition to traditional cataract surgery was found to be safe and resulted in lowered intraocular pressure and a reduction in medication use. The study also found that the long-term presence of the microstent did not have a negative impact on the corneal endothelium
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