Blepharitis: This condition is characterized by inflammation of the eyelids, often accompanied by scaling, redness, and irritation, which matches the symptoms described. It's a common condition that can be caused by a variety of factors including poor eyelid hygiene, makeup use, or underlying skin conditions like seborrheic dermatitis or rosacea.

Seborrheic Dermatitis: This is a skin condition that can cause scaly patches, red skin, and stubborn dandruff, often affecting oily areas of the body like the face, including the eyelids. Its symptoms overlap with those described, making it a plausible diagnosis.
Allergic Conjunctivitis: Although typically associated with signs of infection or more pronounced allergic reactions, some forms of allergic conjunctivitis can present with irritation and scaling of the eyelids without overt signs of infection, especially if the allergen is something like makeup or contact lens solution.
Eczema (Atopic Dermatitis): Eczema can affect any part of the body, including the eyelids, causing dryness, itching, and scaling. Given its prevalence and the fact that it can be localized, it's a reasonable consideration.

Basal Cell Carcinoma or Other Skin Cancers: Although rare, skin cancers can present with chronic irritation or lesions on the eyelids. Given the potential severity of missing such a diagnosis, it's crucial to consider, especially in individuals with risk factors like prolonged sun exposure.
Lupus or Other Autoimmune Disorders: Systemic lupus erythematosus and other autoimmune diseases can cause a wide range of symptoms, including skin rashes and lesions that might resemble irritated eyelids. These conditions are critical to identify due to their systemic implications.

Sarcoidosis: This is a condition where inflammatory cells form lumps known as granulomas in various parts of the body, including the skin and eyes. It can cause a variety of symptoms, including skin lesions and eye problems, but it's much less common than other conditions listed here.
Demodex Infestation: Demodex mites can live on human hair follicles and are often found on the face, including the eyelids. An overinfestation can lead to symptoms like irritation and scaling, but this is less commonly identified as a primary cause compared to other dermatological conditions.