Blepharitis, or eyelid inflammation, one of the most common problems, is characterized by erythematous eyelids with accumulation of debris along the eyelid margin. Malignant eyelid tumors may be associated with lash loss and erosion of normal eyelid structures.
Moon phases depend on the position of both the Sun and Moon with respect to the Earth. The 4 primary phases of the Moon are: new, first quarter, full and third quarter.
A crescent moon above Earth's horizon is featured in this image photographed by an Expedition 24 crew member in 2010. In Western culture, the four principal lunar phases are new moon, first quarter, full moon, and third quarter (also known as last quarter). These are the instants when the Moon's apparent geocentric celestial longitude minus the Sun's apparent geocentric celestial longitude is 0Â°, 90Â°, 180Â° and 270Â°, respectively.