An elderly person while trying to read a book at about 25 cm from the eyes finds the imago appears blurred because of the decreasing effectiveness of the ciliary muscles and the loss of flexibility of the lens. This defect of the eyes is called

The condition described is presbyopia, a natural age-related vision defect. In a healthy eye, the ciliary muscles contract to increase the lens's curvature (decreasing focal length) to focus on near objects, a process known as accommodation [c1]. However, with aging, the crystalline lens gradually loses its flexibility and elasticity, becoming stiffer and harder [t1, t4]. Simultaneously, the ciliary muscles weaken and become less effective [t1, t2]. This combined loss of accommodative power causes the near point of the eye to recede beyond the standard 25 cm, making reading and close-up tasks appear blurred [t2, t4]. While hypermetropia also involves difficulty seeing near objects, presbyopia is specifically distinguished by its physiological cause related to the aging process of the lens and ciliary body [t6]. It is often corrected using convex lenses or bifocal lenses if the person also suffers from myopia [t2].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.1.1 Power of Accommodation > p. 162
2. [2] https://www.ncbi.nlm.nih.gov/books/NBK560568/