bubble_chart Overview

Senile cataract is the most common type of acquired cataract, often occurring in individuals aged 40 to 50 and above. The lens itself gradually becomes cloudy without any obvious systemic or local disease cause being identified. It typically affects both eyes, either sequentially or simultaneously, and the progression from onset to maturity can take several months to years. Depending on the location of the opacity, senile cataracts can be classified into two types: nuclear and cortical. Cortical cataracts are further divided into peripheral cortical and posterior subcapsular cortical types.

bubble_chart Etiology

Senile degeneration: senile nutritional disorders, metabolic disturbances, senile over-regulation of lens degeneration and hair whitening, similar to the mechanism of skin wrinkle formation.

bubble_chart Pathological Changes

There are two factors that cause lens opacity: ① The lens fibers absorb water and swell; ② The morphology and properties of the lens capsule epithelial cells change.

In senile cataract, it begins between the lens nucleus and cortex. Initially, narrow fissures and vacuoles appear between the lens fibers, followed by swelling and volume changes of the fibers themselves, resulting in a fine, sandy opacity. The lens fibers derived from epithelial cells become highly swollen and form a large vesicle containing a nucleus, known as a vesicular cell. These fibers eventually degenerate, forming spherical bodies of varying sizes called myelin globules, or Morgagni's globules. The lens capsule epithelial cells lose their normal arrangement, partially disappear, and proliferate. In the advanced stage, the degenerative substances in the cortex lose water, causing the lens to shrink. Clinically, white patches on the capsule are observed, which result from the proliferation of some capsule epithelial cells.

bubble_chart Clinical Manifestations

(1) Clinical Manifestations

Opacity first appears in the cortex of the lens and then progresses to the entire lens. Before opacity appears, the fiber lamellae of the lens separate to form transparent clefts, a phenomenon known as hydration. This includes transparent microvesicles, centrifugal separation of fiber lamellae, and radial longitudinal water clefts, which can be considered early manifestations of the condition.

(2) Clinical Stages

1. Incipient Stage: Gray-white opacities typically first appear in the deep cortex of the lens equator, presenting as wedge-shaped and arranged radially. When the opacities do not involve the pupillary area, vision is usually not significantly affected.

2. Developmental Stage (also called the Swelling Stage): The wedge-shaped opacities gradually extend toward the center, and other parts of the lens also develop opacities of varying thickness, forming heterogeneous opaque areas. Due to increased water content in the cortex, the lens becomes swollen. At this stage, the anterior chamber becomes shallow, and the lens surface often exhibits uniform striations with a silky luster. Because a layer of transparent cortex remains beneath the anterior capsule, the iris shadow can be observed under oblique illumination. This stage may induce glaucoma in individuals predisposed to it. Vision decline becomes noticeable and progressively worsens.

3. Immature Stage: Over months or years, the excess water within the lens gradually dissipates, and the swelling subsides. The entire lens becomes opaque, and the iris shadow disappears. This stage is ideal for surgery.

4. Hypermature Stage: The duration of the mature stage varies. If prolonged, water absorption occurs, the stellate striations of the lens disappear, and the lens becomes uniformly gray-white or shows irregular small white spots on the gray-white opacity. The lens fibers liquefy into a milky fluid, and the brown-yellow nucleus sinks downward, resulting in Morgagnian cataract.

The anterior capsule becomes lax and forms folds, and the capsule may thicken and become opaque. Simultaneously, the anterior chamber deepens, and iris tremor occurs. The lens nucleus may oscillate with eye movement, potentially rupturing the capsule and causing lens dislocation, secondary glaucoma, and liquefaction of the vitreous, complicating cataract surgery. In recent years, improvements in equipment and surgical techniques have enabled satisfactory surgical outcomes during both the swelling and hypermature stages.

bubble_chart Auxiliary Examination

To understand the full picture of the lens, a thorough examination should be conducted in a dark room after full dilation. The specific methods are as follows:

1. **Focal Illumination Examination**: Direct light is used to illuminate the lens to check for any opacity or dislocation.

2. **Iris Shadow Test**: A narrow beam of light is projected at a 45-degree angle from the pupillary margin onto the lens. If the opacity is located in the nucleus, a crescent-shaped transparent area will appear between the opacity and the pupillary margin. The heavier the opacity, the narrower the shadow. If the entire lens is opaque, the crescent-shaped shadow will completely disappear.

3. **Ophthalmoscope Retroillumination**: Light is directed into the pupil. Normally, a uniform red reflex is observed. If there is opacity in the lens or refractive media, black spots or patches may appear in the red reflex. The patient may be asked to move their eyes to observe whether the shadows shift, helping to determine the location of the opacity.

4. **Slit-Lamp Examination**: An optical section is created using the slit lamp. From front to back, multiple alternating bright and dark layers can be seen, representing different stages of the lens nucleus. The transparency of each layer varies, with the anterior capsule, the anterior surface of the adult nucleus, and the posterior surface of the embryonic nucleus being relatively clearer.

bubble_chart Treatment Measures

1. Drug Therapy

Mostly used in the early stages or when the cataract is not fully mature, aiming to delay its progression or improve vision. Clinical observations indicate that most drugs have no significant effect on already opacified lenses. Based on biochemical research on the lens, these drugs can promote the metabolism of nicotinamide, mononucleotides, and nucleoside monophosphates in lens epithelial cells to prevent cataract formation. Alternatively, they may protect the SH group of lens proteins to prevent protein denaturation or supplement large amounts of vitamin C and inorganic salts (such as potassium, sodium, calcium, etc.) to prevent changes in the lens's chemical composition. The following drugs may be tried.

(1) Glutathione (GSH)

A tripeptide composed of glutamic acid, cysteine, and glycine. The reduced form is GSH, while the oxidized form is GSSG. The SH group of reduced GSH participates in redox reactions in the body, detoxifies, and activates several important enzyme systems, making it crucial for maintaining normal lens metabolism. In 1966, Oguchi et al. first used GSH to treat senile cataracts with good results.

1. Main Pharmacological Effects

⑴ GSH can maintain lens transparency.

⑵ The SH group of GSH sustains the activity of certain enzymes.

⑶ It prevents soluble proteins from becoming insoluble.

⑷ Lens opacity is related to abnormal tyrosine metabolism forming quinones. The SH group can inhibit quinone formation.

2. Dosage: 100 mg intramuscular injection every other day. 4% solution for eye drops, 4–6 times daily.

(2) α-Mercaptopropionylglycine (Thiola)

An SH-group compound structurally similar to GSH, with strong reducing properties. It maintains lens transparency and prevents the pathological process of liver qi counterflow leading to lens opacity.

Dosage: ① Oral: 1–2 tablets, three times daily. ② Eye drops: 6–10 times daily.

(3) Catalin (Cataract Eye Drops)

This is 1-hydroxy-pyridine, an aldose reductase inhibitor.

According to research by Kakinoki Shunosuke, senile cataracts are associated with abnormal tryptophan metabolism, where the abnormal metabolite quinolinic acid can cause cataracts.

This drug can be administered via injection, eye drops, or orally for traumatic, complicated, or senile cataracts.

(4) Phacolysin

This is sodium 5,12-dihydroazapentacene disulfonate. It easily penetrates tissues into the lens and has a strong affinity for soluble lens proteins, preventing quinones from oxidizing and opacifying the lens. It also activates protein hydrolases in aqueous humor, promoting the breakdown and absorption of already opacified lens proteins. It has redox properties, enhancing the metabolism of the lens and entire eye tissue to prevent cataract progression.

Dosage: Local eye drops, 3–5 times daily.

(5) Xiannuoling

Main ingredients: calf lens protein (10 mg), vitamin C (5 mg), vitamin B₂ (0.2 mg), potassium iodide (0.1 mg), strychnine (0.01 mg).

Dosage: Three times daily, one sublingual tablet before meals.

(6) Liming Eye Drops

Contains potassium iodide, sodium iodide, vitamin B₁, C, etc. Administer 3–5 times daily.

(7) Parotin

Regulates abnormal permeability of the lens capsule, mainly used for senile cataracts.

Dosage: ① 3 mg intramuscular injection twice weekly. ② 0.2 mg subconjunctival injection. ③ 10–12 mg orally, 2–3 times daily.

(8) Thyroxine

can promote the synthesis of amino acids into proteins and maintain lens transparency. A 0.02% solution of this product can be used for eye drops, 2-3 times daily.

(9) Others

Systemic use of vitamin C, B₂, E, etc.

(10) Chinese medicinals treatment

such as oral administration of Cizhu Wan, Shijie Yeguang Wan, etc.

II. Surgical treatment

1. White internal visual obstruction needle aspiration.

2. White internal visual obstruction extracapsular extraction.

3. White internal visual obstruction intracapsular extraction.

4. Cataractopiesis with metal needle.