Accommodative insufficiency (AI) involves the inability of the eye to focus properly on an object.
Accommodation is the adjustment of the curvature of the
lens
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
to focus on objects near and far.
In this condition, amplitude of accommodation of a person is lesser compared to physiological limits for his age.
AI is generally considered separate from
presbyopia
Presbyopia is physiological insufficiency of accommodation associated with the aging of the eye that results in progressively worsening ability to focus clearly on close objects. Also known as age-related farsightedness (or age-related long si ...
, but mechanically both conditions represent a difficulty engaging the near vision system (accommodation) to see near objects clearly. Presbyopia is physiological insufficiency of accommodation due to age related changes in lens (decreased elasticity and increased hardness) and ciliary muscle power.
AI is commonly present in people with
convergence insufficiency
Convergence insufficiency is a sensory and neuromuscular anomaly of the binocular vision system, characterized by a reduced ability of the eyes to turn towards each other, or sustain convergence.
Symptoms
The symptoms and signs associated with con ...
.
Categories
Accommodative insufficiency is further categorised into different categories.
Ill-sustained accommodation
Ill-sustained accommodation is a type of accommodative insufficiency in which, range of accommodation will be normal, but after excessive near work accommodative power will decrease.
Paralysis of accommodation
In paralysis of accommodation, amplitude of accommodation is either markedly reduced or completely absent (
cycloplegia
Cycloplegia is paralysis of the ciliary muscle of the eye, resulting in a loss of accommodation. Because of the paralysis of the ciliary muscle, the curvature of the lens can no longer be adjusted to focus on nearby objects. This results in sim ...
).
It may occur due to ciliary muscle paralysis or oculomotor nerve paralysis.
Parasypatholytic drugs like atropine will also cause paralysis of accommodation.
Unequal accommodation
If there is amplitude of accommodation between the eyes differ 0.5 dioptre or more, it is considered as unequal.
Organic diseases,
head trauma
A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...
or functional
amblyopia
Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...
may be responsible for unequal accommodation.
Causes
Premature sclerosis of lens or ciliary muscle weaknesses due to systemic or local cases may cause accommodative insufficiency.
Systemic causes of ciliary muscle weakness include
diabetes
Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
,
pregnancy
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occurs by sexual intercourse, but ca ...
, stress,
malnutrition
Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues a ...
etc.
Open angle glaucoma
Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...
,
Iridocyclitis
Uveitis () is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and i ...
etc. are known local causes.
Signs and symptoms
Near vision will be blurred, and asthenopic symptoms like
head ache and
eye strain
Eye strain, also known as asthenopia (from Greek ''a-sthen-opia'', grc, ἀσθενωπία, ), is a common eye condition that manifests through non-specific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache, and ...
may occur while reading.
Reduction of amplitude of accommodation by 2 dioptre or more is one of the important sign.
Treatment
Underlying systemic or local causes should be treated. Weak
convex lens
A lens is a transmissive optics, optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a #Compound lenses, compound lens consists of several simp ...
es may be prescribed for near vision until accommodation improves to normal level.
Accommodation exercises may be advised to improve accommodative power.
References
Eye diseases
Medical signs
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