Certified Ophthalmic Assistant Practice Exam

What effect is caused by spectacle lenses that are not aligned with the patient's visual axis?

1. Lens distortion

2. Induced prism effect

3. Increased glare

4. Color aberration

The correct answer is: Induced prism effect

The induced prism effect occurs when spectacle lenses are not properly aligned with the patient's visual axis. This misalignment can cause light to bend in an unintended manner as it passes through the lenses, leading to a perceived shift in the position of objects. Essentially, the lack of alignment creates an effective prism that changes the direction of incoming light, which can disrupt the patient’s normal binocular vision and depth perception. When the lenses are positioned correctly, they should accommodate the visual axis, allowing the light to enter each eye without distortion or deviation. However, if the lenses are rotated or misaligned, this can lead to symptoms such as double vision, headaches, and difficulty focusing. Therefore, the induced prism effect is a critical consideration in lens fitting, as proper alignment is essential for optimal vision correction. In contrast, other options like lens distortion, increased glare, and color aberration deal with different visual phenomena. For instance, lens distortion would be more related to the shape of the lens itself rather than its alignment, while increased glare typically results from surface reflection or lighting conditions rather than misalignment. Color aberration involves the failure of a lens to focus all colors to the same convergence point and is unrelated to the alignment of the visual axis. Understanding these distinctions highlights the importance