Lacrimal sac

Lacrimal sac A little structure that drains away tears. Little channels called canaliculi are present in the inner corner of the eyelids into which tears drain. From there, they are dumped into the lacrimal sac and then drained into the nose and throat. Disorders of...

Anti-relective coating

Anti-relective coating Specialized coating to eliminate light reflections off lenses that can cause unwanted glare, especially at night. Especially useful for high index lenses or lenses that are relatively thick. This coating is considered to be revolutionary for...

Astigmatism

Astigmatism An optical error in which there are two or more abnormal focal point in the eye, unlike hyperopia (farsightedness) or myopia (nearsightedness) where there is just one abnormal focal point that needs correcting. (See Refractive Disorders for more details.)...

Lens

Lens The structure that sits behind the pupil and which acts to focus light onto the retina just as a camera lens focus light onto the film inside. (See Eye Anatomy and How The Eye Works for more details.) The lens is normally crystal clear, and cannot be seen with...