Evaluation of the impact of COPD severity grading and oxygen saturation on the retinal nerve fiber layer thickness and subfoveal choroidal thickness in COPD patients

Abstract

Abstract Background Retinal and choroidal blood vessels are involved in many systemic diseases because they are complex vascular systems. Chronic obstructive pulmonary disease is considered as an inflammatory disease that affects many systems and coexists with several co-morbidities. Systemic inflammation and hypoxia affect the macula, choroid, retinal nerve fiber layer (RNFL), and blood vessels. Ocular co-morbidities have been detected in COPD patients. These can be quantitatively and qualitatively evaluated by Spectral Domain Optical Coherence Tomography (SD-OCT). Enhanced depth imaging OCT (EDI-OCT) is a quite new technique that utilizes light with an extended wavelength. An apparent relation has been found between chronic pulmonary disease and low corneal endothelial cell density preoperatively. So this work aimed to assess the impact of COPD severity grading and oxygen saturation on retinal nerve fiber layer thickness and subfoveal choroidal thickness. Results This was a case-control study, recruited 50 COPD patients and another 50 healthy volunteers as a control group. Measuring the thickness of the RNFL (superior, inferior, nasal, and temporal) in the four quadrants as well as the subfoveal choroidal thickness was done to both groups. The RNFL thickness in all quadrants and the SFCT in the COPD group were statistically significantly thinner in comparison to the control group. The RNFL thickness (mean) was 79.16 ± 10.49 μm compared to 96.30 ± 4.66 μm in the control group (p value 0.001). The SFCT (mean) was 213.12 ± 25.61 μm compared to 354.62 ± 53.82 μm in the control group (p value 0.001). The degree of thinning of the RNFL (superior, inferior, and temporal) and the SCFT was related to COPD (GOLD) stages severity (p value 0.001). Nasal RNFL was thinned out in all stages of COPD (GOLD) but with no statistical significance (p value 0.264). Conclusion The choroid and retina seem to be of the affected tissues during the progressive inflammatory course of COPD. Ocular pathologies should be evaluated in patients with systemic hypoxia. The eye examination for COPD patients can be carried out via a non-invasive procedure such as the OCT and the changes in the RNFL and SFCT thickness could be used as indicators for the severity of COPD.

Keywords

• Retina
• Choroid
• Thickness
• Hypoxia
• Pulmonary disease
• Optical coherence tomography