Symptoms can be serious, and the disease can be fatal â especially for babies, the elderly, and people with weakened immune systems. When influenza pandemics occur, they spread quickly, often killing large numbers of previously healthy people. From 1918 to 1919, a flu pandemic hit the U.S. in three waves.
Enucleation (Eyeball Removal). Enucleation is the removal of an eye. It is an irreversible method of treating various disorders of the eye. Reasons for enucleation include: 1  Severe untreatable trauma, such as a perforated or ruptured eyeball. 2  Uncontrollable glaucoma.
Spherical aberration. Spherical aberration is an optical effect observed in an optical device (lens, mirror, etc.) that occurs due to the increased refraction of light rays when they strike a lens or a reflection of light rays when they strike a mirror near its edge, in comparison with those that strike nearer the centre.