What is one characteristic of compound myopic astigmatism?

• A. Requires only a plus lens
• B. Occurs in one eye only
• C. Involves myopia in both meridians
• D. Adjacent lenses of different powers

Answer: (C)

Compound myopic astigmatism is characterized by myopia being present in both principal meridians. This means that, unlike other forms of astigmatism, where one meridian may be emmetropic (normal vision) or hyperopic (farsighted), both meridians in compound myopic astigmatism exhibit myopia. The condition often requires correction with cylindrical lenses in addition to spherical lenses to adequately address the refractive errors in each meridian.

The other choices do not accurately describe the nature of compound myopic astigmatism. For example, requiring only a plus lens would not apply, as both meridians are myopic, which typically necessitates the use of minus lenses for correction. Additionally, while compound myopic astigmatism can occur in one eye, it is not restricted to unilateral presentation and is often bilateral. Finally, the term "adjacent lenses of different powers" does not specifically relate to this condition and does not describe the standard correction methods employed for this type of astigmatism.