Refractive Errors

Refractive errors occur when abnormalities of the eye prevent the proper focus of light on the retina. Emmetropia refers to an eye free of refractive errors. Common Refractive Errors Two common types of refractive errors are myopia and hyperopia. Myopia Myopia, also...

Common Eye Disorders

Amblyopia - a reduction or dimming of vision in an eye that appears to be normal. Also commonly known as lazy eye, amblyopia is an eye condition noted by reduced vision not correctable by glasses or contact lenses and is not due to any eye disease. The brain does not...

Principles of Atoric Lens Design

Industry studies have shown that approximately 70% of all spectacle wearers receive a cylinder correction for astigmatism. Further, 50% of these wearers have corrections with over 0.50 D of cylinder power. This article will show that conventional lens design does not...

Fundamentals of Progressive Lenses

A progressive addition lens (PAL) is a type of multifocal lens that employs a surface with a continuously smooth increase in addition (Plus) power. The curvature of the surface increases from its minimum value in the distance zone to its maximum value in the near zone...

Darryl Meister, ABOM

Darryl Meister is the Technical Marketing Coordinator for Carl Zeiss Vision, one of the largest manufacturers of ophthalmic lenses in the world. He has been active in the optical industry since 1990 and holds both the ABO Master in Ophthalmic Optics certification and...

Thomas Porter, O.D, FAAO

Dr. Porter, is an Assistant Professor in the Department of Ophthalmology at Saint Louis University's Eye Institute where he also serves as director of the Low Vision Service. He also serves as an Adjunct Assistant Professor in the Department of Occupational...