Cataract pathology

2021-02-02 12:00 AM

A congenital cataract may be accompanied by strabismus, fibrillation of the eyeball and some manifestations of systemic diseases such as malformations of the skull, skeletal system, intellectual development disorder.

Define

Cataracts are an opacity of the vitreous body caused by various causes.

This is the leading cause of blindness in developing countries. However, if the patient has an artificial lens replacement surgery, he or she will still be able to restore vision

The causes of cataracts

There are many causes of cataracts:

Congenital cataracts, cataracts in children

Congenital cataracts are cataracts that are present from birth.

Cataracts that appear in the first year of life are called childhood cataracts.

The cause of the congenital cataract can be hereditary or the embryo disease during pregnancy.

The morphology of congenital cataracts:

Cataract: vitreous cataract is opaque in the subshell and in the envelope of the anterior and posterior poles of the vitreous body.

Perforated joint: perforated or star-shaped is the chisel in the Y-shaped joint of the fetus has little effect on eyesight.

Chisel: cataract is the chisel of the embryonic nucleus of both the embryonic nucleus and the fetal nucleus.

Percussion: a chisel is a small chisel in the epithelium and the anterior glass body without affecting the crust.

Photo: Glass embryo chisel

Chisel or regional chisel: the most common congenital cataract. The opaque layer covers a transparent centre, this opaque layer is surrounded by a transparent shell.

Complete vitreous cataract: complete turbidity of vitreous fibres, completely losing the pink light of the pupil.

Membrane charring: occurs when the vitreous proteins are dissipated, causing the anterior and posterior capsules to merge into a solid white film.

A congenital cataract may be accompanied by strabismus, fibrillation of the eyeball and some manifestations of systemic diseases such as malformations of the skull, skeletal system, intellectual development disorder.

Cataract due to old age

Ageing cataracts are the leading cause of vision loss in the elderly. In the US, the rate of cataract is 50% in the age group 65 to 74, an increase of 70% in those over 70. In Vietnam (according to the 2002 Ophthalmology survey) the rate of cataract is in 71.3% of people over 50 years old.

The pathogenesis of old age cataracts is caused by many factors and is not well understood. The cause of the old cataract is due to a disorder of the catabolism of glucose in the vitreous, which disturbs the protein synthesis of the vitreous body.

Age-related cataracts have 3 forms:

Glass casing: In the elderly, the vitreous nucleus is hardened and yellow in colour. Excessive hardening and yellowing are called cataracts and cause cloudiness in the central region. Cataract usually progresses slowly. In the early stage, the gradual hardening of the nucleus causes an increase in vitreous refractive index causing the refraction of the eye to change to myopia. In cases of progressive turbidity, many of the vitreous individuals become completely cloudy and turn brown, known as a brown cataract.

Cataract: The cataract (also called the wedge-shaped chisel) always stays in the eyes and is often disproportionate. These wedge-shaped chisels can enlarge and merge to create larger chiselled areas. When the entire shell from the capsule to the nucleus becomes white opaque, it is called a mature cataract. When the degenerative vitreous material passes through the vitreous, it leaves a crumpled and shrinking layer called an overcooked cataract. When the crust liquefies, the nucleus can move freely inside the sac called the Morgagni cataract.

Picture: Morgagni overcooked glass chisels

The posterior subcapsular cataract: posterior subcapsular cataract is localized in the posterior shell and is usually located on the axis. The posterior subcapsular cataracts are mainly due to old age, can also be the result of trauma, corticosteroid medication and ionizing radiation.

Cataract due to injury

Post-traumatic cataracts can be caused by mechanical damage, physical impact and osmotic effects.

Cataract after crushing injury

A crushing injury can cause a very early cataract or a late sequel. Glass chisel due to crushing may be in only one area or all of the glass body. The first manifestation is usually a star-shaped or rose-shaped chisel of the posterior sheath usually located on the axis. This rose-shaped chisel can progress to a total cataract.

Crushing injuries can cause tearing of the condom, causing the aqueous humour to cling to the inside, the vitreous fibres absorb water, causing cataracts very quickly.

A major blow injury can rupture part or all of the Zinn's wires, resulting in a deviation or loss of vitreous.

Cataract after trauma

Trans-vitreous trauma often causes cataracts at the site of the tear, usually progressing gradually to complete turbidity. Sometimes a small wound on the anterior condom can heal on its own, leaving a small, stable cloudy area.

When the vitreous capsule was wide torn pieces of the vitreous substance bulged through the tear of the sac in the anterior chamber. Usually, the yeasts of aqueous humour can cloud and destroy the vitreous plates.

Cataract caused by radiation

Ionizing radiation: The vitreous is very sensitive to ionizing radiation. Ionizing radiation in the X-ray range (0.001-10 nm wavelength) can cause cataracts in some people at low doses.

Infrared radiation: Glass chisels in glassblowers.

Ultraviolet radiation

Short-wave radiation.

Chemical charring

Alkaline burns often lead to cataracts. Acid burns are less likely to cause cataracts.

Pathological cataracts

Diabetes: Cataracts are a common cause of vision damage in people with diabetes. Two types of diabetic cataract are common:

True diabetic cataracts (or snowflakes) are seen in young people with uncorrected diabetes.

Ageing cataracts in diabetic patients: Cataracts are more common at a younger age than in non-diabetic patients. Metabolism of the accumulation of Sorbitol in the vitreous body accompanied by subsequent hydration changes and the increase in glycosylation of the diabetic vitreous protein may contribute to the accelerating rate of cataract formation. old age in diabetic patients.

Hypocalcemia (cataract in Tetani disease): disease usually in the two eyes, manifested by iridescent cloudy spots on the anterior and posterior shells, under the vitreous and often separated from the capsule by an area in.

Cataracts after uveitis.

Figure: Cataract after eyelid iritis

Secondary cataracts in eyes with a history of uveitis. The most typical is the posterior subcapsular cataract. May change on the anterior lens of the lens with pigment spots or patches of iris and anterior vitreous. Cataracts after uveitis can progress to ripening.

Drug-induced cataracts.

Many drugs and chemicals can cause cataracts.

Corticosteroid: The posterior subcapsular cataract can occur after long-term use of topical and systemic corticosteroids.

Some drugs can cause cataracts such as

Phenothiazines (psychotropic drugs group).

Amiodaron antiarrhythmic drug.

Anticholinesterase drugs. Pupil

Examination of the patient with cataracts

Exploit medical history

Patients often visit for the following signs and symptoms:

Decreased vision: More or less visual impairment depending on the degree and location of turbidity. Vision loss, especially vision far away. In the early stage, the patient can see black spots in front of his eyes.

Nearsightedness: in some elderly people there is a decrease in the number of reading glasses because the hardening of the nucleus increases the refractive power of the vitreous body causing mild or moderate myopia, closer vision.

Blurred vision: Patients with cataracts may complain of blurred vision to the point of being blinding in daylight, headlights in the front or similar lighting conditions at night.

Patients with a history of eye injury may have monocular double, severe astigmatism.

It is necessary to exploit the history of eye diseases and systemic diseases: uveitis, severe myopia, glaucoma, diabetes ...

Examination of the patient with cataracts

Examination for normal light cataract, fundoscopy and microscope. Need to dilate the pupils to assess the location and level of turbidity.

Pupil illuminance: if the vitreous is clear, the pupil light is uniformly pink. If the lens is cloudy, dark spots will be seen against the pink pupil light.

Examination by slit lamp on a microscope will evaluate the position, level of turbidity and preliminary assessment of the hardness of the vitreous nucleus:

Location: cataract, shell chisel, glass capsule ...

Level of cataract: turbidity begins, turbidity progresses, almost completely turbid, complete turbidity.

Examination of the pupil: reflect the pupil to direct light.

Find the direction of light in all directions.

Principle of treatment of cataracts

Treatment of cataracts with drugs

To date, there is no drug that can slow, prevent or reverse the development of cataracts. Many anti-cataract drugs are being studied, including drugs that reduce Sorbitol, aspirin, drugs that increase Glutathione and antioxidant vitamins such as vitamin C and vitamin E.

Treatment of cataracts with surgery

The most common indication for surgical treatment of cataracts is the patient's desire to improve visual function. Surgical decisions based on impaired visual function have a significant impact on work and birth. daily activities of the patient.

Evaluation before surgery

Asking the history of systemic and eye diseases: It is important to detect eye and system conditions that may affect surgical methods or postoperative visual prognosis.

Eye exam:

Visual acuity: At least sensory light is required

Pupil reflectance: Examination of direct light reflection

Direction of light: Direction of light in all directions is good. If the light direction is weak or unilateral, the pupil reflex is not sensitive, the prognosis of postoperative vision is less effective, it is necessary to explain clearly to the patient before surgery.

Refractive corneal refraction, eyeball axis length (ultrasound examination).

Measure eye pressure, pump to wash the religion.

Body examination: Detection of acute or progressive diseases (diabetes, tuberculosis, etc.), neighboring inflammatory foci (sinusitis, tooth decay ...) requiring stable treatment.

The methods of cataract surgery

The intra-capsular lens surgery: is the collection of whole vitreous bodies with the same layer of vitreous. After surgery, the patient must wear glasses. Today this surgical method is only applicable in cases of aphasia, the vitreous suspension system is too weak.

Surgery to remove the extra-capsular (extra-capsular): Is to remove the nucleus and the entire glass shell material and the center of the anterior capsule, leaving the posterior shell. This method limits a number of complications after surgery and leaves behind the vitreous to create a good anatomical position to fix the artificial lens.

The surgery to remove the vitreous body of the artificial vitreous body: After taking the whole nucleus and the vitreous shell, the artificial glass body is placed in the back room.

Phacoemulsification: An ultrasonic-driven needle is used to puree the vitreous nucleus and suck the vitreous substance through the pinhole. Phaco surgery is now widely used in many ophthalmic facilities. Surgery has advantages: a small incision, a closed room, so it is safer, eyesight recovers well, reducing postoperative astigmatism and complications.

Prevent some causes of cataracts

Cataract due to injury: Adequate means of labour protection are required.

Pathological cataracts: treatment & monitoring of patients with diabetes, uveitis,

Congenital cataract: when the mother is pregnant in the first 3 months, it is necessary to avoid contact with deformities such as radiation, toxic chemicals, pesticides, people with the flu, and fever.

On the road need to wear a hat and eye protection.