What does a higher prescription number indicate in positive lenses?

A higher prescription number in positive lenses indicates a stronger magnification effect for farsightedness, which is also known as hyperopia. Positive lenses are designed to converge light rays before they enter the eye, making them essential for individuals who have difficulty seeing nearby objects clearly due to their eyes focusing light behind the retina.

As the prescription number increases, the degree of convergence increases, resulting in a stronger magnification effect. This is important for helping patients with hyperopia see objects up close more clearly. The relationship between the prescription number and the power of the lenses is direct; the higher the number, the greater the lens power needed to correct the refractive error.

In contrast, the other options present situations that either do not accurately describe the function of positive lenses or are unrelated to the primary purpose of lens prescriptions. For instance, weaker magnification for myopia would pertain to negative lenses designed to diverge light for individuals who are nearsighted, while 'no change in lens effectiveness' and 'reduced weight of the lenses' do not reflect the implication of a higher prescription number in positive lenses.