Spherophakia, Isolated
Patient Information
Characteristics
Background and History
Spherophakia is a rare condition in which the lens of the eye is abnormally small and more spherical than usual. It may occur alone or in combination with other anomalies of the eye and skeletal system. In the condition described here it is an isolated ocular finding.
Clinical Correlations
Individuals with this condition have abnormally small and spherically-shaped lens that cause extreme nearsightedness. The lenses may dislocate completely. Some patients have glaucoma which is apparently secondary to the lens blockage of fluid circulation in the eye. There is no evidence of a primary glaucoma. Patients are nearsighted as a result of the abnormal shape of the lens. There are no skeletal or other systemic abnormalities.
Genetics
Inheritance
This condition is inherited in an autosomal recessive pattern. A gene change (mutation) has been identified. Carrier parents with one copy of the mutation are clinically normal but if both parents have the mutation, they can expect on average that one out of four of their children will have this form of spherophakia.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
The diagnosis can only be made by examination of the eye by an ophthalmologist. Vision correction with glasses or contact lenses can be helpful. Surgical removal of the abnormal lenses is indicated when they interfere with vision or cause glaucoma. It is important that patients have frequent eye examinations throughout their lives. The presence of glaucoma requires prompt attention.
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