What causes zonular weakness?
A number of the causes of weakened zonules can present challenges during cataract surgery. These include trauma, congenital syndromes (eg, Marfan’s, homocystinuria), chronic uveitis, retinitis pigmentosa, previous ocular surgery (glaucoma, retina), and pseudoexfoliation (PXF).
What is zonular instability?
Zonular instability is no doubt the bane of many a cataract surgeon, as the risk for the cataract moving posteriorly or the vitreous moving anteriorly becomes higher, putting patients at risk for such complications as a retinal hole or detachment.
What is zonular weakness?
Zonular weakness can be caused by disease or trauma, and its presence can make cataract surgery more challenging. Fortunately, there are adjunctive devices to effectively manage it and achieve successful outcomes. Causes. Certain diseases of the eye are associated with zonular weakness or insufficiency.
What is Zonular cataract?
Lamellar or zonular cataract is a hereditary cataract that is transmitted in an autosomal dominant mode. The crystalline opacities are located at the level of the primary fibers in the embryonic nucleus. This cataract is usually bilateral and asymmetrical.
What is zonular dehiscence?
Definition. Rupture of the fibrous strands connecting the ciliary body and the crystalline lens of the eye. [
What do zonular fibers do?
The zonular fibers pass over the ciliary body and are attached to the capsule of the lens a short distance in front of its equator. These fibers change the focusing power of the eye by changing the tension of the fibers by contraction and relaxation of the ciliary muscle.
What causes zonular cataract?
This type of congenital cataract may be caused by mutations in the heat-shock transcription factor-4 gene (HSF4) located at 16q21-q22. 1. It is inherited in an autosomal dominant pattern. Another morphologically different autosomal dominant congenital cataract has been linked to the same locus (see Maumenee, 1979).
What is the use of crystalline lens?
The crystalline lens of the eye is a natural lens which produces one third of the eye’s total optical power and focuses light into an image on the retina (the light-sensitive tissue at the back of the eye). The crystalline lens is elastic which allows it to flex in order to change its shape.
Where do zonules attach?
lens capsule
The zonules attach to the lens capsule 2 mm anterior and 1 mm posterior to the equator, and arise of the ciliary epithelium from the pars plana region as well as from the valleys between the ciliary processes in the pars plicata.
When the ciliary muscle is relaxed?
When the ciliary muscle is relaxed, the choroid acts like a spring pulling on the lens via the zonule fibers causing the lens to become flat. When the ciliary muscle contracts, it stretches the choroid, releasing the tension on the lens and the lens becomes thicker.
What do Zonular fibers do?
What is Zonular dehiscence?