landmark glaucoma trials

LANDMARK GLAUCOMA STUDIES DR SYED SHOEB AHMAD QUEEN ELIZABETH HOSPITAL KOTA KINABALU

Borneo Glaucoma Update 2017

Glaucoma Studies  

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OHTS CIGTS EMGT CNTGS AGIS TTS

Ocular Hypertension Treatment Study Collaborative Initial Glaucoma Treatment Study Early Manifest Glaucoma Trial Collaborative Normal Tension Glaucoma Study Advanced Glaucoma Intervention Study Tube vs. Trabeculectomy Study

Ocular Hypertension Treatment Study (OHTS) PURPOSE:  To evaluate the safety and efficacy of topical hypotensive medications in preventing or delaying the onset of visual field loss and/or optic nerve damage in subjects with ocular hypertension (OHT).  Identify the baseline demographic and clinical risk factors for developing POAG.

PARTICIPANTS:  1637 patients with OHT were recruited between 1994 & 1996.

STUDY DESIGN:  Multicenter randomized controlled clinical trial comparing observation with medical therapy for OHT.  Patients between the age groups 40-80 years with normal VF and optic discs.  Untreated IOP of 24-32 mmHg in one eye and 21-32 mmHg in fellow eye.  Randomized to observation or a stepped topical medical regimen.  Patients in observation group were offered treatment after 7.5 years of follow-up.

MAIN OUTCOME MEASURE:  Assessment of VFs and stereoscopic optic disc photos.

RESULTS 2002 (5 years):  Topical medication was effective in delaying or preventing the onset of POAG. A

22.5% decrease in IOP in treatment arm (vs. 4% in control arm) was associated with a reduction in the development of POAG from 9.5% in controls to 4.4% in treatment group at 60 months of follow-up.

The risk of onset of POAG was associated with:  Increasing age.  Vertical and horizontal cup:disc ratios (C:D R).  Pattern standard deviation.  IOP at baseline (1 mmHg increase=10% increase in relative risk).  Central corneal thickness was a powerful predictor for the development of POAG (the relative risk of POAG increased 81% for every 40µ thinning of cornea).

RESULTS 2007:  The same predictors for the development of POAG were identified independently in the OHTS observation group and the European Glaucoma Prevention Study (EGPS) placebo group.  Thus, the OHTS prediction model was validated in the EGPS placebo group.

RESULTS 2010:  The proportion of patients who developed POAG was 0.22 in the original observation group and 0.16 in the original medication group.  The primary purpose of follow-up study was to determine whether delaying treatment resulted in persistently increased risk of conversion to glaucoma, even after initiation of therapy. On follow-up there was no further divergence in the Kaplan-Meier curves after both groups received IOP-lowering treatment.

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LEARNING POINTS: ◦ OHTS reported that 9.5% of the patients in the control group progressed. Thus, 90.5 % did not. Most of the end points were disc related, not functional. ◦ Not all patients with OHT need treatment. ◦ Patients to be considered for treatment include: baseline high IOP (>26 mmHg), thin corneas (30 mmHg or any IOP >35 mmHg. ◦ VA trabeculectomy>trabeculectomy(ATT)

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Trabeculectomy>Argon-laser-trabeculoplasty>trabeculectomy(TAT)

PARTICIPANTS:  789 eyes of 591 patients with medically uncontrolled OAG recruited from 1988 to 1992.  STUDY DESIGN:  Multicenter randomized controlled clinical trial comparing 2 treatment sequences (ATT & TAT) for patients with OAG uncontrolled by medical therapy. 

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RESULTS: Black patients did better with ATT Less progression White patients did better with TAT In the first year of follow-up in white patients, the TAT group had greater visual acuity loss than the ATT group, but by 7 years the 2 groups had equivalent VAs. Encapsulated blebs were slightly commoner in patients with prior ALT. But this difference was not statistically significant. Lower IOP was associated with less VF loss. Eyes with average IOP of 14 mmHg or less during the first 18 months after the first surgical intervention, or eyes with IOP of 18 mmHg or less at all visits throughout the study had significantly less VF loss.

LEARNING POINTS: Blacks and whites differed in the way they benefit from the 2 treatment sequences.  Blacks should be considered for laser (ALT) first.  Whites should be considered for trabeculectomy first.  Lower IOP was associated with reduced progression of VF damage. Subjects with IOP