Which following statement is NOT true regarding night myopia?

• A. Increased pupil size leads to a decrease in the depth of focus
• B. Pupil size at night typically decreases which stimulates myopia
• C. Increased pupil size caused increased spherical aberrations
• D. Low light levels lead to the inability to fully relax accommodation

Answer: (B)

In dim lighting, the eye’s pupil dilates, which reduces depth of focus, increases optical aberrations, and tends to keep accommodation slightly more engaged, producing a myopic shift at distance known as night myopia. The statement that is not true is the one claiming that pupil size decreases at night to stimulate myopia—it’s the opposite: the pupil typically dilates in low light, not constricts. Because the pupil is larger at night, depth of field narrows (making retinal image blur more likely unless accommodation adjusts), spherical aberrations increase, and the accommodation can remain more active or not fully relax, all contributing to a nocturnal myopic shift. The other statements reflect these mechanisms: a larger pupil lowers depth of focus; a larger pupil increases spherical aberrations; and low light can hinder full relaxation of accommodation.