Presbyopia
The cause of this patient's blurry vision when reading is presbyopia, which results from age-related loss of lens flexibility (decreased compliance) beginning around age 45 years. 1
Pathophysiology
Presbyopia occurs as part of the natural aging process when the crystalline lens loses its ability to change shape and focus on near objects. 1 This condition specifically results from:
- Loss of lens flexibility and increased lens stiffness that prevents adequate accommodation for near vision 1
- Progressive thickening of the lens with age, which compounds the inability to adjust its shape 2
- Changes in viscoelastic properties of both the lens capsule and lens matrix 3
The key distinguishing feature in this case is that the patient specifically has difficulty with near vision (reading) at age 55, which is the hallmark presentation of presbyopia rather than other refractive errors. 1
Why Other Options Are Incorrect
- Myopia (nearsightedness) causes difficulty seeing distant objects, not near objects, and its prevalence actually decreases with age 1
- Hyperopia (farsightedness) can affect near vision but is not specifically caused by decreased lens compliance; it results from the eye's inability to bring parallel light rays into focus on the fovea 1
- Astigmatism results from irregular corneal or lenticular curvature, not decreased lens compliance 1
- Emmetropia is the absence of refractive error (normal vision) 1
Clinical Context
Presbyopia typically begins affecting individuals around age 40-45 years and progresses thereafter. 1 The prevalence of presbyopia increases with age, and by age 55, most individuals require some form of near vision correction. 1 The natural history involves progressive loss of accommodative amplitude, with most facility to accommodate lost by age 55. 3