Oxygen toxicity: the potential negative side effects of supplemental oxygen therapy in patients with ocular pathologies
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PURPOSE: To investigate the plausibility of clinically significant oxygen toxicity in patients with retinal disorders being treated with hyperoxia therapy. Supplemental oxygen therapy is a promising form of treatment that may help reduce ischemia and the subsequent symptoms in patients suffering from diabetic retinopathy (DR), retinal vein occlusions (RVOs), and age-related macular degeneration (AMD). Currently, few studies perform ongoing assessments of current hyperoxia trials in patient populations. By investigating a current cohort of patients using supplemental oxygen to mitigate symptoms in their ocular conditions, we hope to demonstrate the extremely low likelihood of oxygen toxicity in patients utilizing hyperoxia therapy. Through these results, we hope to demonstrate that supplemental oxygen therapy is a viable, safe method of treatment for patients with ocular disorders. METHODS: A cohort of 16 patients was analyzed for changes in their C Reactive Protein (CRP), white blood cell count (WBC), hematocrit (Hct), and hemoglobin (Hb) levels after continuous use of hyperoxia therapy as part of treatment for varying retinal disorders. All study patients were diagnosed and under treatment at Beth Israel Deaconess Medical Center in Boston, MA. Patients diagnosed with diabetic retinopathy, retinal vein occlusions, or age-related macular degeneration were included in the study. Each of these patients must have also been prescribed 5 L/min of nocturnal hyperoxia therapy. Patients with insufficient data either before or after beginning the hyperoxia therapy were excluded. Primary outcome variables were arranged as pre- and post- hyperoxia therapy data points for CRP, WBC, Hb, and Hct. P-values below 0.05 would indicate statistically significant risk of oxygen toxicity in these variables under the current hyperoxia treatment. RESULTS: The mean age of the sample population was 64, with 6 of the 16 patients diagnosed with diabetes (37.5%). Patient groups were divided into diabetic vs. non-diabetic to assess whether or not one group was affected differently by the hyperoxia therapy. Results showed p-values well over 0.05 for both groups, indicating that oxygen toxicity is not a major risk factor when using supplemental oxygen under the study’s conditions. CONCLUSION: A large number of patients with diabetes suffer from retinal problems, especially with the onset of old age. These problems eventually require treatment via eye injections, laser, and even surgery in order to preserve vision and mitigate edema and ischemia. Given the high cost and invasive nature of these procedures, hyperoxia therapy provides a safe and potentially beneficial alternative to mitigate the symptoms of these disorders. This study hoped to demonstrate the plausibility of widespread clinical application for supplemental oxygen therapy in retina patients, while concluding that oxygen toxicity is not a significant risk factor in this type of treatment. The outcomes of this study support this hypothesis, and lay the groundwork for future studies that may assess the risks of oxygen toxicity on a larger scale. More research is required to gauge the true risks of oxygen toxicity in patients using supplemental oxygen. A case-controlled longitudinal study would also prove useful in providing data on changes in visual acuity and other experimental factors of interest, while accounting for several limitations present in this study.