Tunica vasculosa lentis
Tunica vasculosa lentis
Description, Causes and Risk Factors:
Tunica vasculosa lentis is a congenital anomaly of the eye that results following failure of embryological primary vitreous and hyaloid vasculature to regress. It is characterized by persistence of various portions of the primary vitreous (embryonic hyaloid vascular system) with hyperplasia of the associated embryonic connective tissue, and associated with microphthalmia, cataract and glaucoma.
Posterior tunica vasculosa lentis: In posterior tunica vasculosa lentis the remnant vascular stalk is seen arising off the optic nerve but not reaching the lens, thus usually not causing cataract. Posterior tunica vasculosa lentis may be associated with abnormal development of the retina, optic nerve and macula, vitreal stalk, vitreal membranes. The purely posterior presentation of posterior tunica vasculosa lentis is termed falciform retinal septum and ablatio falcicormis congentia.
A combination of anterior and posterior tunica vasculosa lentis: A combination of anterior and posterior tunica vasculosa lentis is the most commonly seen clinical presentation.
Anterior tunica vasculosa lentis: Anterior tunica vasculosa lentis occurs when the remnant vascular stalk is seen attached to the back of the lens but no longer extends back to the optic nerve. This form is typically associated with cataract, glaucoma and retrolenticular membrane.
Tunica vasculosa lentis is typically found in full term infants. In majority of cases, the abnormality can be noted at birth or within the first few weeks of life.
During embryonic development of the eye, the compartment between the retina and crystalline lens contains a vascular system (hyaloid artery) that provides nutrients for the developing eye. The hyaloids vessels and the primary vitreous are supposed to regress in the third trimester of pregnancy.
Tunica vasculosa lentis may be due to a defect in the regression of the primary vitreous or in the formation of the secondary vitreous (that fills the developing second eye and is derived from the inner retinal cells starting in the 9th week of gestation) or to a combination of both. The persistent hyaloid vasculature and mesenchymal tissue from the embryonic primary vitreous in a microphthalmic eye leads to the clinical spectrum of Tunica vasculosa lentis. The exact cause and pathogenetical mechanisms, however, remain poorly understood.
In some patients with tunica vasculosa lentis, mutations in the NDP gene have been identified. NDP mutations have been associated with a spectrum of pediatric retinal vitreopathies. Among them, Norrie disease represents the most severe phenotype, while tunica vasculosa lentis together with X-linked familial exudative vitreoretinopathy (FEVR), Coats disease and retinopathy of prematurity (ROP) represent the less severe phenotypes.
The pathogenetic role of the NDP mutations in tunica vasculosa lentis was supported by findings in Ndp knockout animal models that demonstrated failure of the primary hyaloid artery and associated structures to regress. One patient with bilateral tunica vasculosa lentis was reported to have a mutation the NDP gene and the mother of this patient was confirmed to be a carrier.
Tunica vasculosa lentis can present in different ways. These include:
Squint (when both eyes don't appear to point in the same direction).
Painful red eye.
Nystagmus (fast to and fro movements of the eyes).
White pupil (leukocoria).
Differential diagnosis may include Coats disease, retinopathy of prematurity (ROP), microphthalmia, incontinentia pigmenti, congenital cataract, and ocular toxocariasis.
Diagnosis is based on comprehensive eye examination and confirmed by ultrasonography, computing tomography (CT) or magnetic resonance imaging (MRI). A cone-shaped retrolental density is a characteristic finding of tunica vasculosa lentis on imaging studies.
Today, the goals in treatment are saving the eye from the complications of untreated tunica vasculosa lentis (mainly glaucoma and phthisis bulbi), saving of useful vision, and achieving acceptable cosmetic outcome.
When the cataract is significant, some authors suggest preventive lens extraction in the first few weeks of life. Lensectomy with or without anterior or total vitrectomy, and trabeculectomy are the surgical procedures that are performed depending on the clinical presentation. It should be noted however, that surgery for tunica vasculosa lentis may be complicated by retinal detachment. Strict case selection is needed, as preoperative retinal or optic nerve abnormalities are particularly associated with poor outcomes.
Strabismus surgery may also be required though fusional potential is usually poor in these patients.
Visual rehabilitation (aphakic contact lens and amblyopia therapy) is possible with eyes that are fairly normal in structure after the lensectomy and membranectomy. In case of the numerous abnormalities of the posterior segment, visual rehabilitation may not be possible. In patients in whom surgery is not possible, the use of a cosmetic contact lens to give a black pupil is necessary. Enucleation of the blind eye may be indicated in case of intractable glaucoma and phthisis bulbi.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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