W4 Near Vision Assessment

What are causes of accommodative dysfunction?

• Systemic and ocular medication

• Ocular trauma

• Inflammatory disease

• Metabolic disorders (diabetes)

• Down’s syndrome/cerebral palsy

• Idiopathic (unknown)

What are symptoms of accommodative dysfunction?

• Headache

• Asthenopia (eye strain)

• Near vision blur

• Difficulty reading

• Difficulty changing focus

What tests are conducted for suspected accommodative dysfunction?

• Amplitude of accommodation- push up/pull down method

• Accommodative facility +- 2.00DS flippers

• Accommodative lag- MEM/modified Notts

What is amplitude of accommodation?

Measure of the closest point at which the eye can focus

What is the procedure for the push up/pull down method?

• Occlude on eye

• Px fixates on smallest line, push card till blur is sustained (Note value in diopters)

• Pull card away until line is clear again (note value in diopters and calculate average- this is AoA)

Why are binocular results better than monocular when working out AoA?

Px are converging

What do we do in younger px eyes in AoA?

-3.00DS lens in front of px eye so near point is moved further away from eyes- you must add 3 to the reading

When do we suspect accommodation insufficiency?

If amp is more than 1.50DS lower than expected for age

Why might some px over 50 not need a near prescription?

• Myopes can simply remove specs

• Px may slide specs down their nose

• Natural monovision- one eye is less myopic/hyperopic than the other eye

What are treatments for presbyopia?

• Spectacle correction

• Corneal inlay (tiny lenses inserted onto cornea)

• Scleral expansion

• Antioxidant drops to soften crystalline lens

• Pharmaceutical drugs stimulate pupil miosis slightly

How can you determine tentative add?

• Determine working distance needs from history and symptoms

• WD - ½ AoA

Whats the procedure for final add?

• Insert tentative add on top of refined prescription

• Instruct px to hold reading chart and read lowest they can

• Add + or - 0.25DS binocularly based on whether vision is blurrier, clearer or the same

How do you determine range of clear vision?

• To calculate closest point of range do 1 / (near add + AoA)

• To calculate furthest point of range do 1 / near add

• Maximum range of clear vision varies between these 2 values (theoretically)

Whats the procedure for determining range of clear vision?

• Move chart forward slowly till letters become blurred (closest point)

• Move chart away slowly till letters become blurred (furthest point)

Why do we not calculate AoA on people over 55?

They don’t accommodate

When may unequal adds be prescribed?

• amblyopia

• Accommodative lag

• Anisometropia (after cataract surgery)

• Very fussy patient