Hemorrhage or Trauma: This is often the most common and immediate concern when patients present with sudden bilateral eye discoloration, as it can result from trauma, leading to periorbital hematoma (bruising around the eyes).

Allergic Reactions: Allergic reactions, including those to insect bites, certain foods, or environmental allergens, can cause bilateral periorbital edema and discoloration.
Infections: Infections such as periorbital cellulitis can cause redness, swelling, and discoloration around the eyes.
Contact Dermatitis: Irritant or allergic contact dermatitis from substances like makeup, soap, or certain plants can lead to skin discoloration and irritation around the eyes.

Orbital Malignancy: Although rare, malignancies affecting the orbit can cause changes in the appearance of the eyes, including discoloration, and are critical not to miss due to their severe prognosis.
Thyroid Ophthalmopathy: Associated with Graves' disease, this condition can cause exophthalmos (bulging of the eyes), periorbital edema, and changes in skin pigmentation around the eyes.
Vascular Malformations: Conditions like cavernous sinus thrombosis or carotid-cavernous fistula can lead to sudden changes in eye appearance, including discoloration, and are medical emergencies.

Ochronosis: A rare condition characterized by the accumulation of homogentisic acid in the body, leading to blue-black pigmentation in connective tissues, including the skin around the eyes.
Argyria: Exposure to silver or silver compounds can cause argyria, leading to a blue-gray discoloration of the skin and mucous membranes, including the eyes.
Melanosis: Certain conditions can cause an increase in melanin around the eyes, leading to discoloration, though these are less common and often associated with other systemic symptoms.