The cataract is often categorized using morphological and/or etiological classifications. Here are Cataracts Classification

A. Related-Age

Based on the patient's age, cataracts are divided into 3: Congenital, Juvenile, and Senile.

1. Congenital Cataracts

Congenital cataracts are cataracts that occur at birth and infants less than 1-year-old. Based on the number of eyes affected, there are two types of congenital cataracts: unilateral and bilateral. Meanwhile, based on the part of the lens that is affected, there are four types of congenital cataracts:

  • Nuclear cataracts are a common form of congenital cataracts. The cloud is located in the central part of the lens.
  • Anterior polar cataracts located in the front part of the eye's lens and often are associated with inherited traits. Some of them are small and do not require surgical intervention.
  • Posterior polar cataracts are also well-defined opacifications but appear and located in the back portion of the lens.
  • Cerulean cataract usually is found in both eyes of infants and is distinguished by small, bluish dots in the lens. Typically, it does not cause vision problems and be associated with inherited tendencies.

Causes of Congenital Cataracts

- Most of the unilateral congenital cataracts are idiopathic and often accompanied by other ocular anomalous diseases such as:
        - Persistent Fetal Vasculature (PFV), 
        - anterior segment dysgenesis, 
        - tumors in the posterior segment. 
These anomalies cause changes in physiological mechanisms in the lens and eventually cause cataracts.
-  Bilateral congenital cataracts are usually the hereditary disease (the most often is autosomal -dominant) and often accompanied by other systemic diseases.
-   Some systemic diseases such as craniofacial syndrome, musculoskeletal and renal disease
- Metabolic diseases (galactosemia, Fabry syndrome, Wilson syndrome) can cause congenital cataracts, especially bilateral ones.
- Maternal infectious diseases and intrauterine infections such as TORCH, varicella, viral choriomeningitis, and HIV can cause congenital cataracts.
-  Tetracycline for treating infections during pregnancy also showed to cause cataracts in newborn babies.

2. Juvenil or Infantile Cataract

Juvenile or childhood cataracts are cataracts that are developing at a young age, which start to form at less than three years and more than six years. Juvenile cataracts can be a continuation of congenital cataracts. 
The juvenile cataract is usually a complication of systemic or metabolic diseases and other diseases such as:
- complicated cataracts that can occur due to local diseases of the eye such as anterior uveitis and retinal detachment,
- Juvenile cataracts due to systemic diseases such as hypoparathyroidism diabetes mellitus
- Juvenile cataracts due to myotonic dystrophy affecting both eyes.

3. Senile Cataracts

Senile cataract is characterized by gradual progressive clouding and thickening of the eye's lens in old age, that is, age over 50 years. Clinically, there are several stages: incipient, intumescent, immature, mature, and hyper-mature (and if more severe is called Morgagni). Clouding and thickening of the lens occur because the lens fibers formed first are always pushed toward the middle. Therefore, the fibers in the center of the lens will become denser (nucleus), dehydrated, accumulation of calcium ions, and sclerosis.

In this nucleus, there is an accumulation of pigment, and the lens becomes less hypermetropic. In the cortex, there are gaps between the lens fibers, which contain water and Ca ion deposits so that the lens becomes thicker, more convex, and swollen, becoming more myopia.

B. Based on location and shape

1. Coronaria (Club or Crown)

The cloud location is far at the edge of the lens and can only be seen if the pupillary mydriasis, in the form of a bowling pin, can be single or multiple, found in 25% of the population diverse shapes.

2. Stellatum (Y suture)

A variation of the form of lamellar cataract, which only involves the outer layer of the lens nucleus embryonic, generally bilateral, does not cause visual reduction unless there is an enlargement.

3. Polaris anterior pyramid

This type is usually round, well-defined, causing opacity on the lens's anterior surface, shaped like a pyramid. Visual impairment depends on the size and location of the cataract.

4. Polaris posterior pyramid

Usually round, delimited, causing opacity on the anterior surface of the lens. Because it is located closer to the retina, this type of cataract causes vision problems.

5. Zonular / lamellar

Zonular/lamellar cataracts are the most common type of congenital cataracts. There are various variations in size, depending on the current developmental impairment in intrauterine. Round or oval in shape, gray in color, surrounds the clear area at the center of the fetal nucleus, radial opacity in the equatorial plane. Opacity indicates a tendency towards density rather than size and persists at the age of 35-55 years. Because of the increase in density, there will be impaired vision with varying degrees. 

C. Maturity

1. Cataracts insipient

Opacity starts from the edge of the equator in the form of bars to the anterior and posterior cortex (cortical cataract). The vacuole is beginning to appear in the cortex. This affliction can give rise to polyopia because the refractive index is not the same in all parts of the lens. This form sometimes persists for a long time.

2. Intumescent cataracts

The turbidity of the lens is accompanied by lens swelling due to degenerative lenses absorbing water. The edema lens pushes the iris so that the front chambers are shallower than normal and cause glaucoma complications. This type of cataract develops rapidly and causes lenticular myopia.

3. Immature cataracts

This type does not affect the entire lens layer. However, lens volume can increase due to increased osmotic pressure due to degenerative lens material and can cause complications in the form of secondary glaucoma.

4. Mature cataracts

Cataracts have affected the entire thickness of the lens. The mature cataract is a stage of the continued development of immature and intact cataracts. The lens discharge has taken place so that the lens returns to normal size, the front of the eye chamber returns to normal depth, the test of negative iris shadow, and lens calcification can occur. Sharp vision decreases to light perception.

 5. Hypermatur cataracts

The mass of the degenerating lens comes out of the lens capsule so that the lens shrinks. On examination, you can see the deep front chambers and the fold of the lens capsule.
If the cataract process continues accompanied by a thick capsule, the cortex degenerates, and the fluid cannot come out. It is called the Morgagni cataract.

D. By shape

1. Cortical (spoke - cuneiform)

The lens opacity process starts from the peripheral lens and continues to extend to the pupillary area. The process can be started from each quadrant, but the inferior nasal region is more prevalent than the other quadrants. The process begins with lens lamella separation caused by lens overhydration. Opacity can occur in the anterior and posterior parts of the lens, and its progression cannot be predicted.

2. Posterior subcapsular (cupuliform - PSC)

The turbidity of the lens is vacuole or granular. The cataract process occurs in the posterior layer of the lens cortex. Because of its location, this type of cataract causes a significant visual reduction. Causa associated with cupuliform cataracts includes age, prolonged use of steroids, trauma, or due to chronic uveitis. This type is one type of cataract that has the fastest progression, so it must be monitored carefully.

3. Nuclear sclerosis

Shortly after 40 years, the central part of the lens will experience sclerosis; this results in a change in the lens refraction index. At an advanced stage, the nucleus will be shaped like an oil droplet. Recommended examinations include retro illumination with direct ophthalmoscopy or retro illumination with slit-lamp on mydriasis pupils.

E. Accompanying diseases

a. Complicated cataracts

Complicated cataracts are cataracts with other eye effects such as inflammation and degenerative processes such as retinal detachment, retinitis pigmentosa, glaucoma, intraocular tumors, ocular ischemia, anterior segment necrosis, buphthalmos, due to a trauma and post eye surgery. Other causes are systemic endocrine diseases such as diabetes mellitus, hypoparathyroidism, galactosemia, and dystrophy myotonia.

  b. Diabetes cataract

Diabetes cataract is a cataract that occurs due to diabetes mellitus.

  c. Traumatic cataract

The trauma of the lens most often causes traumatic cataracts due to foreign bodies or blunt trauma to the eyeball.

d. Toxic cataract

Toxic cataracts occur due to toxic substances that affect the eyes, both systemically or locally, such as corticosteroids.

e. Secondary cataract

Secondary cataracts occur due to the formation of fibrosis tissue in the remaining lens left behind due to extracapsular eye surgery.