Partial reversal of color vision impairment in type 2 diabetes associated with obstructive sleep apnea

Objective: Tritan anomaly is a known acquired color defect seen in diabetic patients, with or without the evidence of clinical signs of diabetic retinopathy (DR). We report a case of a 45-year-old diabetic patient with tritan pattern color defect associated with obstructive sleep apnea and its partial reversal with continuous positive airway pressure (CPAP) ventilation. Methods: A 45-year-old male with diabetes, wildlife photographer by profession, presented with specific complaints of seeing all objects in the surrounding with a greenish tinge in both the eyes. He underwent a comprehensive eye examination including Farnsworth-Munsel 100 (FM 100) hue test, multifocal electroretinogram, microperimetry, spectral domain optical coherence tomography (SDOCT), and arterial oxygen saturation. Results: The subject was found to have a low arterial oxygen saturation (PaO2) of 86%. He was then advised inhalation of 100% oxygen for 15 min, following which he reported improvement in his visual symptoms. FM 100, OCT, and microperimetry were repeated after oxygenation. He was referred to a specialty hospital for further evaluation of the cause for reduced blood oxygen saturation and was further advised for sleep study, where he was diagnosed to have obstructive sleep apnea (OSA) with an apnea-hypopnea index of 20.9. Conclusion: The subject was advised weight loss measures and oral application of continuous positive airway pressure. Since then, he is under our regular follow-up and has never experienced or complained of any color vision problems. This case report highlights the presence of associated systemic disorders like obstructive sleep apnea in individuals with diabetes that can present with color vision problems.