Refractive Errors and Visual Symptoms

The video tutorial covers various refractive errors of the eye, starting with emmetropia, which is normal vision. It then explains myopia, or shortsightedness, and its correction with concave lenses. Hypermetropia, or longsightedness, is discussed next, along with its correction using convex lenses. Astigmatism is explained as a condition where refraction varies in different meridia of the eye, leading to blurred vision, and is corrected with cylindrical lenses. The video also covers anisometropia, where the refraction in both eyes is unequal, and aniseikonia, where the size and shape of images differ between the two retinas.

What is the state of refraction called when parallel rays of light focus on the retina with accommodation at rest?

• Hypermetropia

• Astigmatism

• Emmetropia

• Myopia

Which of the following is NOT a type of refractive error?

• Astigmatism

• Hypermetropia

• Myopia

• Presbyopia

What type of lens is used to correct myopia?

• Bifocal lens

• Cylindrical lens

• Concave lens

• Convex lens

In hypermetropia, where is the image formed relative to the retina?

• In front of the retina

• On the cornea

• Behind the retina

• On the retina

Astigmatism is characterized by:

• Images forming behind the retina

• Images forming in front of the retina

• Refraction varying in different meridia of the eye

• Equal refraction in both eyes

What is the main visual symptom of astigmatism?

• Double vision

• Blurred vision

• Color blindness

• Tunnel vision

Anisometropia is a condition where:

• The shape of images is equal in both eyes

• The size of images is equal in both eyes

• The refraction in both eyes is unequal

• Both eyes have equal refraction

What is the concern when anisometropia exceeds a certain degree?

• It leads to double vision

• It is not tolerated beyond four diopters

• It results in tunnel vision

• It causes color blindness

Aniseikonia involves differences in:

• Depth perception

• Image size and/or shape between the two retinas

• Light sensitivity

• Color perception

What percentage of difference in image size or shape is tolerated in aniseikonia?

• 20%

• 15%

• 5%

• 10%