You would expect "I wish I had longer arms!" Presbyopia is the slow loss of the lens's focusing power with age. The patient can no longer add enough power for near work, so print must be held farther away to clear up. Arms run out of length before the print clears, and that is the complaint patients describe.
The eye focuses up close through accommodation. The ciliary muscle contracts, the zonule fibers relax, and the lens becomes rounder. A rounder lens has more plus power, which pulls near images onto the retina. The lens hardens from birth onward, and by about age 40 to 45 the loss of elasticity starts to matter. That is why presbyopia shows up in the fourth or fifth decade of life and why so many people that age buy reading glasses. Presbyopia can sit on top of any refractive error. It happens in emmetropia, myopia, hyperopia, and astigmatism. Distance vision is untouched, so a presbyope complains about near work only. Common complaints are trouble with small print, sewing, and reading in dim light. Reading glasses or a bifocal add put the missing plus power back.
An adult over 40 who pushes print away and reads fine at arm's length is describing presbyopia. Recognizing the symptom and taking a clear near-vision history is a core part of the COA refraction content area.
Incorrect Answers
- A. Holding print very close and reading it well fits an uncorrected myope. Presbyopes push print away instead.
- B. Needing more light for distance vision points to a media or retinal problem, such as cataract. Presbyopia does not blur distance.
- C. Trouble with changing light levels is a light adaptation issue. It is not caused by a hardened, less flexible lens.
Testing Pearls
- Presbyopia = age-related loss of accommodation, not a disease of the retina.
- Symptoms usually begin at about age 40 to 45.
- Accommodation works when the ciliary muscle contracts and the lens rounds up.
- Presbyopia can be present with any refractive error, including emmetropia.
- The lens hardens from birth, but the problem shows up in the fourth or fifth decade. Near print is tested at the reading distance, usually about 14 to 16 inches, with the patient's reading correction.
References
- American Academy of Ophthalmology. Ophthalmic Medical Assisting: An Independent Study Course. Chapter 5, Optics and Refractive States of the Eye.
- American Academy of Ophthalmology. Ophthalmic Medical Assisting: An Independent Study Course. Chapter 2, Anatomy and Physiology of the Eye.
