Question
A patient with fair skin and coarse hair suffering from osteoporosis, mental retardation and seizure disorder presented with decreased visual acuity and double vision.
On examination of the eyes,following picture of lens is seen bilaterally.What would be the most probable diagnosis?
A. Ocular trauma.
B. Homocystinuria.
C. Hyperinsulinemia.
D. Marfan’s syndrome.
Show Answer
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Correct Answer » B
Explanation
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Ans:B. Homocystinuria.
The patient is suffering from inferior dislocation of lens.
Ectopia lentis
- It is a displacement or malposition of the eye’s crystalline lens from its normal location.
- A partial dislocation of a lens is termed lens subluxation ; a complete dislocation of a lens is termed lens luxation .
Pathophysiology
- Disruption or dysfunction of the zonular fibers of the lens.
Anterior lens luxation
- With anterior lens luxation, the lens pushes into the iris or actually enters the anterior chamber of the eye. This can cause glaucoma, uveitis, or damage to the cornea. Anterior lens luxation is considered to be an ophthalmological emergency.
Posterior lens luxation
- With posterior lens luxation, the lens falls back into the vitreous humour and lies on the floor of the eye. This type causes fewer problems than anterior lens luxation, although glaucoma or ocular inflammation may occur.
Common presenting symptoms (visual disturbance) include the following:
- Red painful eye (secondary to trauma)
- Decreased distance visual acuity (secondary to astigmatism or myopia)
- Poor near vision (loss of accommodative power)
- Monocular diplopia.
- Retinal detachment is one of the most serious consequences of a dislocated lens.
Cause:
- Traumatic dislocation is the most common cause
- Most common systemic conditions that are associated with ectopia lentis:
- Marfan syndrome (bilateral,upward and outward)
- Most frequent cause of heritable ectopia lentis. The syndrome is transmitted as an autosomal dominant trait
- Features include tall stature, arachnodactyly, joint laxity, mitral valve prolapse, aortic dilatation, axial myopia, and increased incidence of retinal detachment.
- Homocystinuria (bilateral,downward and inwards)
- An inborn error of metabolism most often caused by a near absence of cystathionine b-synthetase (the enzyme that converts homocysteine to cystathionine).
- Patients typically have fair skin with coarse hair, osteoporosis, mental retardation (nearly 50%), seizure disorder, marfanoid habitus, and poor circulation.
- Weill–Marchesani syndrome(downwards)
- Characterized by skeletal malformations (eg, short stature, brachycephaly, limited joint mobility, well-developed muscular appearance) and ocular abnormalities (eg, ectopia lentis, microspherophakia, lenticular myopia).
- Sulfite oxidase deficiency
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