Anomalies of accommodation

Notes to accompany 2nd Year Undergraduate City University Clinical Practice Lecture

Dr Simon Barnard



The facility enabling the change in dioptric power of the crystalline lens thereby altering the focus of the eye


Assessment of accommodation

Accommodative fatigue

Apart from overuse, factors that influence onset of fatigue include

Symptoms of accommodative fatigue

Treatment of fatigue

Failure of accommodation


Age of onset

Symptoms of presbyopia

Patients complain of reading difficulty in poor light, tired eyes after reading and BLURRED VISION for reading


Prescribe correction so that near point of focus is brought within normal working distance

Determination of reading addition

(b) measure amplitudes of accommodation

(c) use amplitudes as a STARTING point to calculate an approximate reading addition

Rule of thumb - leave 1/3rd accommodation in reserve

Check clarity and range. Double check with +&- additions

Pre-senile cataract

Cataract is likely to reduce accommodation

May be unilateral

Unequal reading adds ?

May have reduced VA

Insufficiency of accommodation

Aetiology of insufficiency

Symptoms of insufficiency

Investigation of insufficiency


Local cause

Central cause

General cause

Treatment management of insufficiency

Ill sustained accommodation

Amplitudes are normal but rapidly diminish with use. Is this the start of a true insufficiency ?…or… rapid onset fatigue ?

Aetiology of Ill sustained accommodation

Investigation & Treatment

Inertia of accommodation

Difficulty in changing focus from distance to near and vice versa

Diagnosis often based on symptomatology



Paralysis of accommodation

May be partial or total, unilateral or bilateral

Signs and symptoms

More accommodative effort required to see near object which is then perceived to be nearer than it actually is and therefore smaller

What does N IIIrd innervate ? ………………….



Spasm of accommodation

Tone of ciliary muscle is increased and a constant accommodative effort is expended by the parasympathetic nervous system. Pseudomyopia produced







Spasm can be further categorised into:

(a) Functional spasm

(b) Organic spasm

Functional spasm

A response to over fatigue and "eye strain". Precipitated by 3 factors:

Treatment of functional spasm

Organic spasm

Irritation of parasympathetic system


- drug induced e.g., physostigmine, pilocarpine, morphine, digitalis

- lesions of brain stem and OM trunk

e.g., anterior uveitis

e.g., diphtheria, tooth extraction

Treatment of organic spasm


Acknowledgements & further reading

Heinemann, Oxford

Simon Barnard November 1999

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