Static and Dynamic Aspects of Angle Perception

definition of Presbyopia

refractive condition where the accommodative ability of the eye is insufficient for carrying out nearwork due to aging

does near or far away vision become blurred for presbyopia

Near vision

definition of Accommodation

adjustment of the dioptric power of the eye brought about by a change in the shape of the crystalline lens

what age is there virtually no accommodation left

55 years old

Any measurable accommodation is probably due to ______?

depth of field

name 4 reasons why Presbyopia is due to

Loss of lens capsule elasticity

Stiffening of the lens nucleus

Growth of the crystalline lens size throughout life

Growth (“hypertrophy”) of the ciliary muscle with age

name the 2 Aetiology

Space reduces due to growth of lens which decreases tension

Decreased zonule tension due to growth of ciliary muscle

what are the Symptoms of presbyopia

➢ Blurring of near vision

➢ Difficulty changing focus between distance and near (and vice versa)

➢ Asthenopia during near-work

➢ If myopic, having to remove distance spectacles for near-work

➢ If significantly myopic or hypermetropic, having to push distance spectacles down nose for near-work

➢ Having to hold print further away to make it clear

what are Clues to presbyopia

➢ Holding print far away when reading (or increasing font size on phone/tablet/kindle)

➢ Reading with spectacles pushed down nose

➢ Age / date of birth

do myopes or hypermetropes have to exert more accommodation through spectacles

Hypermetropes

This means that the onset of presbyopic symptoms may be earlier in spectacle-wearing?

hypermyopes compared to myopes

do myopes or hypermetropes have to exert more accommodation for contact lenses?

Myopes

The onset of symptoms may be earlier in ______ contact lens wearers compared to myopic spectacle wearers

myopic

Hypermetropes exert less accommodation at ____ when they wear contact lenses

near

Onset of presbyopic symptoms earlier in _______?

hypermetropes than myopes

onset of symptoms may be ______ in hypermetropic contact lens wearers compared to hypermetropic spectacle wearers

later

when can a patient be considered to be presbyopic

when they require a “near addition” to overcome symptoms experienced during near-work

What is the near addition?

amount of extra positive spherical power added to the distance prescription and is also known as the “reading addition”, “reading add” or “add”

what is the general idea for prescribing near addition

the lowest add (least plus) which would be expected based on the patient’s age, acuity and working distance

why is the lowest add prescribed for near addition

This will maximise the range of working distances over which the add will give clear vision

The higher (more plus) the near addition is, the _______ the working distance

shorter

what is the only exception for near addition

include anisometropia (3D of anisometropia will usually equate to 0.25D difference in adds) and unilateral pseudophakia (or aphakia)