Presbyopia

Presbyopia is the age related loss of accommodation, the eye's ability to focus on near objects, that begins in the early to mid 40s and progresses until the late 50s to early 60s. It is universal and is not a disease. It results from stiffening of the lens, loss of elasticity of the lens capsule and weakening of ciliary muscle function. It affects around 1.8 billion people worldwide, and uncorrected presbyopia is a major cause of reduced productivity.

• Accommodative amplitude falls from about 14 dioptres at age 10 to about 2 dioptres at age 50 and about 1 dioptre at 60.
• Onset is earlier in hyperopes, people in hot climates, and people with diabetes, low light, small stature or smoking, or taking certain drugs.
• Premature presbyopia (before 40 years): diabetes, multiple sclerosis, cardiovascular disease, anaemia, trauma, drugs (antihistamines, antidepressants, antipsychotics, antispasmodics, antihypertensives, alcohol), uncorrected hyperopia, glaucoma, accommodative insufficiency.
• Consequences: difficulty reading, eye strain, headaches, reduced near work, falls with bifocal use.

• Blurred near vision, holding reading material at arm's length, needing more light, eye strain and headaches after near work, difficulty switching focus, small print difficult, symptoms worse in the evening, tired eyes.
• Distance vision is unaffected unless coexisting error.
• Examination: reduced near point of accommodation (push up test), near acuity improved with plus lenses, normal ocular health.
• Red flags: onset before 40 years, sudden loss of near vision, unilateral presbyopia, pupillary abnormalities (Adie pupil, third nerve palsy), drug history, diabetes, neurological symptoms, flashes or floaters, pain, field loss, double vision.

• Clinical, by age and symptoms, with a distance refraction followed by near addition testing.
• Subjective refraction and near add at the working distance (typically 40 cm); near point of accommodation, amplitude of accommodation (Donders table).
• Full eye examination including intraocular pressure and dilated fundus examination, especially after 40 years.
• Blood glucose or HbA1c in premature presbyopia.
• Differentials: hyperopia, accommodative insufficiency, cataract (nuclear sclerosis may mimic), macular disease, convergence insufficiency, drug induced cycloplegia.

• Optical correction (approximate near addition by age): about plus 1.00 dioptre at age 40 to 44, plus 1.50 at 45 to 49, plus 2.00 at 50 to 54, plus 2.50 at 55 to 60, adjusted to the working distance and the person's need.
  • Single vision reading glasses (near only).
  • Bifocals, trifocals, or progressive addition lenses (smooth transition from distance to near, with a learning period of 1 to 2 weeks).
  • Occupational (office) lenses for computer work.
  • Multifocal or monovision contact lenses.
• Surgical options: monovision or blended vision laser vision correction (LASIK, PRK); corneal inlays; refractive lens exchange with multifocal, extended depth of focus or accommodating intraocular lens (risks include night glare and halos, reduced contrast sensitivity); scleral procedures are not recommended.
• Pharmacological: pilocarpine 1.25 percent eye drops, 1 drop in each eye once daily (a second drop may be used 3 to 6 hours after the first); it constricts the pupil and increases depth of focus for 6 hours. Side effects include headache, brow ache, reduced night vision, red eyes, and rare retinal tear and detachment (dilated fundus examination before starting); avoid in uveitis, retinal disease and angle closure risk.
• Lighting, larger print and magnifiers as adjuncts.
• Treat premature presbyopia causes: control diabetes, review drugs, correct hyperopia.
• Review every 2 years as near add increases; refer for sudden onset, associated neurological symptoms, or ocular disease.