The lens is the lens of a camera, projecting light onto the retina so that we can see the colorful world clearly. Abnormalities in the eye and systemic conditions can lead to clouding of the lens and the formation of cataracts. Cataracts can lead to vision loss, decreased contrast sensitivity, glare, monocular diplopia or hyperopia, and are common in middle-aged and elderly people and patients with trauma. Professor Hampton shares 18 lens abnormalities at Medscape for your study.
The lens is differentiated from epidermal ectodermal cells into lens vesicles, then gradually differentiated into lens fibers, which gather in the center to form the lens nucleus. The anterior pole is the positive “Y” suture and the posterior pole is the inverted “Y” suture (as shown in the figure above). The “Y” suture is surrounded by the lens cortex and the lens nucleus within it. Infections during fetal life, such as rubella virus, can cause abnormalities in the lens suture and are often associated with the development of pediatric cataracts.
The figure above shows a congenital positive anterior “Y” suture cataract and an inverted posterior “Y” suture cataract. The “Y” slit cataract is X-linked or autosomal recessive and can be unilateral or bilateral. It does not usually cause visual problems, but only affects vision when the nucleus or perinuclear cortex of the cataract is cloudy. Viral infections, trauma, or metabolic factors may be the cause of these cataracts.
The embryonic nuclear cataract shown above, also known as a central dusty cataract, is usually a round, milky white clouding confined to the center of the lens. It is autosomal dominant and usually occurs bilaterally, with small eyes and corneas.
The embryonic nucleus cataract shown above is fine-grained, progresses slowly, and often has little effect on vision; it can be avoided if it does not progress and the patient has good vision.
The anterior pole cataract shown above is caused by the fact that the lens vesicles are not completely detached from the ectoderm during the embryonic period. The clouding is located under the anterior capsule and is in the form of small round white dots. It can be occasional or combined with other eye diseases and is autosomal dominant, mostly bilateral. However, if the anterior polar cataract progresses, it may cause strabismus, amblyopia and refractive aberration, which may lead to vision loss.
The conical lens shown above is a lens malformation in which the anterior or posterior capsule of the lens expands outward respectively. The anteriorly dilated lens is more commonly referred to as the anterior conical lens and is often associated with Alport’s syndrome, spina bifida, or Waardenburg’s syndrome; the posteriorly dilated lens is referred to as the posterior conical lens. The conical lens can cause astigmatism in the early stages and later can lead to cataract formation or even spontaneous rupture of the lens.
The blue dot cataract shown above, which often occurs bilaterally, is a small blue dot-like clouding of the lens cortex.
In this type of cataract, the clouding is located in the subcapsular part of the posterior pole of the lens and is yellow or white in color. The entire clouded area is disc-shaped and often exists together with the clouding of the cortex and nucleus. This type of cataract is usually idiopathic, but can also be seen in people with diabetes, long-term steroid hormone use, Down syndrome, and trauma.
The cortical cataract shown above in an adolescent diabetic patient with poor glycemic control is due to impaired lens metabolism. The glucose content of the lens increases and a large amount of glucose is converted to sorbitol, which builds up in the lens, increasing osmotic pressure and water absorption by the lens, resulting in fibrous swelling and degeneration, leading to cortical cataract, which can affect vision and discomfort such as glare as it progresses.
In the mature cataract shown above, the lens is completely opalescent and the corresponding vision is severely reduced, which is a manifestation of the mature stage of cataract development. It is non-specific and can often occur in diseases such as retinal detachment, trauma, uveitis, and diabetes. Surgical removal is the best treatment for mature cataracts, in addition to surgery to lower intraocular pressure.
The shield-shaped cataract shown above in a patient with long-term allergic dermatitis is seen as a thick white clouding under the anterior capsule. The typical presentation of this type of cataract is shield-like or star-shaped with anterior capsule folds. It is commonly seen in patients with immune disorders and also in patients with trauma, and the clouding of the anterior subcapsular and cortex may be due to proliferation and degeneration of the lens epithelium.
A partially resorbed cataract that has dissolved and formed a dense white membrane with the anterior and posterior capsules adhering together is often the result of ocular trauma, as well as congenital rubella syndrome, Hallermann-Streiff syndrome, and Lowe syndrome.
Depending on the location and extent of the trauma, a limited cortical clouding may develop in the early stages or progress rapidly to a complete clouding. Cataract with lens constriction and hemicrania sinking is shown.
A patient with Marfan syndrome is shown above with a subluxation of the lens superior to the nose in the right eye and a similar picture in the left eye. A portion of the lens can be observed in the equatorial part of the temporal inferior part of the lens, which is located behind the iris. Lens dislocation is commonly seen in patients with Marfan syndrome, homocystinuria, and ocular trauma.
The lens and cornea are adherent as shown above, and the congenital abnormality is due to defects in the corneal stroma, posterior elastic layer, and endothelium. Acquired lens-corneal adhesions are often secondary to perforated corneal ulcers and ocular trauma. It can be treated with corneal transplantation and IOL implantation depending on the situation to restore the patient’s visual function.
The above picture shows a cataract in a patient with myotonic dystrophy. The clouding of the lens is Christmas tree-like, and the clouding of the lens can be found to be multicolored under slit lamp. This type of cataract develops in both eyes and is common in patients with myotonic dystrophy.
The sunflower-like cataract shown above is commonly seen in patients with hepatomegaly. It can also be seen in patients with intraocular copper foreign bodies or copper sulfate eye drops. This type of cataract is also seen in patients with lung cancer and multiple myeloma.
The above image shows a senile cataract with radiolucent cortical opacification. Geriatric cataract is one of the major blinding eye diseases, and its pathogenesis may be related to various factors such as environmental, nutritional, metabolic and genetic factors. It can be divided into cortical cataract, nuclear cataract and subcapsular cataract according to its site of occurrence.
Surgical extraction is currently the main method for treating all kinds of lens abnormal cataracts.