NationMaster - Encyclopedia: Pseudomyopia

Pseudomyopia refers to an intermittent and temporary shift in refraction of the eye towards myopia. It differs from true myopia in that the focusing of light in front of the retina is due to a transient spasm of the ciliary muscle causing an increase in the refractive power of the eye. It may be either organic, through stimulation of the parasympathetic nervous system, or functional in origin, through eye strain or fatigue of ocular systems. It is common in young adults who have active accommodation, and classically occurs after a change in visual requirements, such as students preparing for an exam, or a change in occupation. The straw seems to be broken, due to refraction of light as it emerges into the air. ... Normal vision. ... Grays FIG. 872- The choroid and iris. ... It has been suggested that Parasympatholytic be merged into this article or section. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ...

The major symptom is intermittent blurring of distance vision particularly noticeable after prolonged periods of near work, and symptoms of asthenopia. The vision may clear temporarily using concave (minus) lenses. The diagnosis is done by cycloplegic refraction using a strong cycloplegic like atropine or homatropine eye drops. Accommodative amplitude and facility may be reduced as a result of the ciliary muscle spasm. Asthenopia is an ophthalmological condition that manifests itself through unspecific symptoms such as fatigue, eye strain, pain in or around the eyes, blurred vision, headache and occasional double vision. ... Cycloplegia is the paralysis of the ciliary muscle, resulting in a loss of accommodation. ... Atropine is a tropane alkaloid extracted from the deadly nightshade (Atropa belladonna) and other plants of the family Solanaceae. ... Homatropine (EquipinÂ®, Isopto HomatropineÂ®) is an anticholinergic medication that inhibits muscarinic acetylcholine receptors and thus the parasympathetic nervous system. ...

Treatment is dependent of the underlying aetiology. Organic causes may include systemic or ocular medications, brain stem injury, or active ocular inflammation such as uveitis. Functional pseudomyopia is managed though modification of working conditions, an updated refraction, or through appropriate ocular exercises. Uveitis specifically refers to inflammation of the middle layer of the eye, termed the uvea but in common usage may refer to any inflammatory process involving the interior of the eye. ...

References

Chan R, Trobe J (2002). "Spasm of accommodation associated with closed head trauma.". J Neuroophthalmol 22 (1): 15-7. PMID 11937900.

Chentsova O, Shatalov O. "Comparative analysis of the efficacy of some methods of conservative treatment of accommodation spasms and myopia in children". Vestn Oftalmol 118 (6): 10-2. PMID 12506647.

See also