Fildena 50 (sildenafil 50 mg) can cause temporary vision changes. The recognized effects include: Blurred vision A blue/green color tinge or altered color perception Increased sensitivity to light These effects are usually temporary and are related to sildenafil's effect on retinal PDE enzymes. F FDA Access Data +1 However, sudden loss or significant decrease of vision in one or both eyes is different and is an emergency. Stop sildenafil and seek urgent medical attention, because rare cases of NAION (a form of optic-nerve injury) have been reported. F FDA Access Data If you tell me what vision change you experienced, how long after taking Fildena 50 it started, and how long it lasted, I can help you judge whether it sounds like a common temporary effect or something that needs medical evaluation.