Efficacy of anterior chamber paracentesis and carbogen in treating acute nonarteritic central retinal artery occlusion

Purpose: To determine whether anterior chamber paracentesis and Carbogen inhalation therapy (95% oxygen, 5% carbon dioxide) produce a significant difference in final Visual acuity in eyes with acute nonarteritic central retinal artery occlusion (CRAO), compared with untreated eyes. Methods: in this retrospective study, the records of 89 consecutive patients seen at the Retina Vascular Unit of Wills Eye Hospital with acute CRAO who received either both anterior chamber paracentesis and Carbogen therapy, or neither anterior chamber paracentesis or Carbogen therapy, were reviewed. Forty patients were treated with both therapies, whereas 49 received neither modality. Visual acuities before treatment and at subsequent follow-up visits were measured. All patients seen within 24 hours of the onset of symptoms were treated, whereas most of those seen after 24 hours were not treated, Results: Stratified Wilcoxon analysis showed no statistically significant difference between the treated and untreated groups (P = 0.87) after adjusting for initial vision. A posthoc power analysis for the difference between two proportions showed that the study had adequate power (0.80) to detect a difference of the proportion of improved patients of 10% versus 25% between the treated and untreated groups. Conclusion: The data suggest that anterior chamber paracentesis and Carbogen therapy offer little benefit for treating acute nonarteritic CRAO.