title: Risk factors for visual field progression in the low-pressure glaucoma treatment study.
abstract: OBJECTIVE
  To investigate risk factors associated with visual field progression in the Low-pressure Glaucoma Treatment Study, a prospective trial designed to compare the effects of the alpha2-adrenergic agonist brimonidine tartrate 0.2% to the beta-adrenergic antagonist timolol maleate 0.5% on visual function in low-pressure glaucoma.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Low-pressure Glaucoma Treatment Study patients with ≥5 visual field tests during follow-up were included. Progression was determined using pointwise linear regression analysis, defined as the same 3 or more visual field locations with a slope more negative than -1.0 dB/year at P < 5%, on 3 consecutive tests. Ocular and systemic risk factors were analyzed using Cox proportional hazards model and further tested for independence in a multivariate model.
  
  
  RESULTS
  A total of 253 eyes of 127 subjects (mean age, 64.7 ± 10.9 years; mean follow-up, 40.6 ± 12 months) were analyzed. Eyes randomized to timolol progressed faster than those randomized to brimonidine (mean rates of progression, -0.38 ± 0.9 vs 0.02 ± 0.7 dB/y, P < .01). In the final multivariate model adjusting for all tested covariates, older age (hazard ratio [HR] = 1.41/decade older, 95% confidence interval [CI] = 1.05 to 1.90, P = .022), use of systemic antihypertensives (HR = 2.53, 95% CI = 1.32 to 4.87, P = .005), and mean ocular perfusion pressure (HR = 1.21/mm Hg lower, 95% CI = 1.12 to 1.31, P < .001) were associated with progression whereas randomization to brimonidine revealed a protective effect (HR = 0.26, 95% CI = 0.12 to 0.55, P < .001).
  
  
  CONCLUSIONS
  While randomization to brimonidine 0.2% was protective compared to timolol 0.5%, lower mean ocular perfusion pressure increased the risk for reaching a progression outcome in the Low-pressure Glaucoma Treatment Study. This suggests that the beneficial effect of randomization to the brimonidine arm was independent of possible differences in ocular perfusion pressures between the 2 treatment arms. The current results and large number of drop-outs in the brimonidine 0.2% arm suggest that more research is necessary before altering clinical practice paradigms.
authors: Einhorn Clinical Research Center, New York Eye and Ear Infirmary, New York, USA. demoraesmd@gmail.com
authors: Carlos Gustavo
authors: CG
authors: De Moraes
authors: Jeffrey M
authors: JM
authors: Liebmann
authors: David S
authors: DS
authors: Greenfield
authors: Stuart K
authors: SK
authors: Gardiner
authors: Robert
authors: R
authors: Ritch
authors: Theodore
authors: T
authors: Krupin
mesh_terms: D000287:Administration, Topical; D058647:Adrenergic alpha-2 Receptor Agonists / Q000008:administration & dosage*; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage*; D000368:Aged; D000068438:Brimonidine Tartrate; D018450:Disease Progression; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects; D057066:Low Tension Glaucoma / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions; D011446:Prospective Studies; D011810:Quinoxalines / Q000008:administration & dosage*; D012307:Risk Factors; D013999:Timolol / Q000008:administration & dosage*; D014786:Vision Disorders / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D000319:Adrenergic beta-Antagonists; D009883:Ophthalmic Solutions; D011810:Quinoxalines; D000068438:Brimonidine Tartrate; D013999:Timolol