Lens shift

Introduction Under normal conditions, the lens is suspended by the lens suspensory ligament on the ciliary body, and its center is almost identical to the visual axis. The partial or total loss or disconnection of the lens suspensory ligament due to congenital, traumatic or pathological causes, etc., causes the suspension force imbalance or loss of the lens to cause the lens to leave the normal physiological position called ectopia lentis. The degree of ligament defect or disconnection (partial or complete) lens ectopic is divided into subluxation and liberation/dislocation; according to the cause of lens ectopic, it is divided into congenital, spontaneous and traumatic.

Cause

Due to the abnormal development of the partial lens suspensory ligament, the traction of the lens is unbalanced, and the lens is displaced in the opposite direction of the poorly developed suspensory ligament, which is called congenital lens ectopic. It can occur as an isolated ocular abnormality alone, or with other ocular dysplasia or systemic dysplasia (mesenchyelia, especially systemic syndrome of bone dysplasia). Eye trauma, especially eyeball contusion, is the most common cause of lens ectopic. Spontaneous lens ectopic is caused by weakening of the lens suspensory ligament or mechanical elongation of the suspensory ligament due to intraocular lesions for some reason such as inflammation and degeneration.

an examination

Related inspection

Lens examination ophthalmoscopy

1. Incomplete dislocation of the lens: Partial relaxation or disconnection of the lens suspensory ligament, the lens is deviated from the normal physiological position, but the displaced lens is still in the vitreous cavity of the pupil area and the posterior plane of the iris, which is called incomplete dislocation of the lens. The symptoms of incomplete dislocation of the lens depend on the extent to which the lens displaces the cupping mesh. If the axis of the lens is still on the visual axis, only lensic myopia due to relaxation of the suspensory ligament and increased curvature of the lens occurs. If the lens axis is tilted horizontally, vertically, or obliquely, it can cause severe astigmatism that is difficult to correct with glasses or contact lenses. The more common incomplete dislocation is the monocular diplopia of the lens. Eye slit lamp examination showed deep anterior chamber, iris tremor, grayish lens, and even suspensory ligament with equatorial fracture. The vitreous helium can enter the anterior chamber with pigment on the surface. Under the ophthalmoscope, a crescent-shaped fundus reflection and a double-eye image can be seen under the ophthalmoscope.

2. Total dislocation of the lens: The lens suspensory ligament is completely disconnected, so that the lens completely leaves the normal physiological position, and the displacement of the anterior chamber or the vitreous cavity is called the total dislocation of the lens.

(1) The lens is incarcerated in the pupil.

(2) The lens is detached into the anterior chamber.

(3) The lens is detached into the vitreous cavity and floats on the vitreous or sinks into the vitreous.

(4) The lens enters the space under the retina and the space under the sclera through the retinal tear.

(5) The lens enters the subconjunctival or under the fascia of the eye through perforation of the cornea ulcer and the rupture of the sclera.

The complete dislocation of the lens is more serious than the consequences of incomplete dislocation. The lens can be incarcerated in the pupil area, causing pupillary block, often occurring after the trauma, the lens axis is rotated 90", the equatorial portion of the lens is located in the pupil region and even the lens is 180° transposition, and the anterior surface of the lens is opposite to the vitreous.

After the lens completely leaves the pupil area, the visual acuity is equivalent to the aphakic vision, and the anterior chamber becomes deeper than the iris tremor. The dislocated lens can move with the change of body position in the early stage. If the lens breaks into the anterior chamber, it sinks below the deeper anterior chamber, and the lens diameter is smaller than when it is in the normal position, and the convexity increases. The transparent lens is in the form of oil droplets, and the lens with golden luster on the edges is a white disc. Part of the lens can cause pupillary blockage during the process of detachment from the vitreous cavity through the pupil into the anterior chamber, causing acute glaucoma. If the pupil area is clear, good vision can be maintained, and the patient can better withstand the cupping network. Sometimes the over-maturing cataract can improve vision due to the lens going into the anterior chamber, and the lens in the anterior chamber can be gradually absorbed. However, it is more common for the lens to repeatedly contact the cornea and the iris ciliary body to cause severe iridocyclitis, corneal dystrophy and acute glaucoma lens to enter the vitreous cavity than the anterior chamber, and the patient can better tolerate but eventually The prognosis is still problematic.

Differential diagnosis

Differential diagnosis of lens displacement:

1. Dislocation or subluxation of the lens: The crystal is connected to the ciliary body by the suspensory ligament and suspended in the aqueous humor. Due to trauma or surgery caused by rupture of the suspensory ligament, incomplete development of the congenital suspensory ligament or dissolution of the suspensory ligament due to intraocular lesions can cause changes in lens position, which is called crystal dislocation or subluxation.

2, corneal lens adhesion: due to Peter abnormalities, some eyes may have a central corneal lens adhesion, accompanied by shallow anterior chamber?, and some are pre-polar cataract. In 1897, Von Hippel reported a case of bovine eye with central corneal opacity and adhesion to the iris. In 1906 Peter described some cases that are now known as Peter anomaly. For more than a century, there has been a debate about whether the disease is a simple disease or whether it has multiple manifestations of the same manifestation.

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