Senile Cataract

Epidemiology: Senile cataract is by far the most frequent form of cataract, accounting for 90% of all cataracts. About 5% of all 70-year-olds and 10% of all 80-year-olds suffer from a cataract requiring surgery.

Ninety percent of all cataracts are senile cataracts.

Etiology: The precise causes of senile cataract have not been identified. As occurrence is often familial, it is important to obtain a detailed family history.

Classification and forms of senile cataracts: The classification according to maturity (Table 7.2) follows the degree of visual impairment and the maturity, which earlier was important to determine the time of surgery. We follow a morphologic classification as morphologic aspects such as the hardness and thickness of the nucleus now influence the surgical procedure (Table 7.3):

Nuclear cataract. In the fourth decade of life, the pressure of peripheral lens fiber production causes hardening of the entire lens, especially the nucleus. The nucleus takes on a yellowish brown color (brunescent nuclear cataract). This may range from reddish brown to nearly black discoloration of the entire lens (black cataract). Because they increase the refractive power of the lens, nuclear cataracts lead to lenticular myopia and occasionally produce a second focal point in the lens with resulting monocular diplopia (Fig. 7.8).

U Nuclear cataracts develop very slowly. Due to the lenticular myopia, near vision (even without eyeglasses) remains good for a long time.

Cortical cataract. Nuclear cataracts are often associated with changes in the lens cortex. It is interesting to note that patients with cortical cataracts tend to have acquired hyperopia in contrast to patients with nuclear cataracts, who tend to be myopic (see above).

Table 7.2 Classification of cataracts according to maturity

Cataract form Visual acuity

Developing cataract

Still full (0.8-1.0)

Immature cataract

Reduced (0.4-0.5)

Developed cataract

Severely reduced (1/50-0.1)

Mature cataract Hypermature cataract

Light and dark perception, perception of hand movements in front of the eye

Table 7.3 Overview of forms of senile cataract

Cataract form

Morphology

Incidence

Symptoms

Nuclear cataract

oo

About 30%, particularly in more severe myopia

- Shades of gray (like looking through frosted glass)

- Blurred vision

anterior

Subcapsular cataract posterior

©0 0

About 50%

- Intense glare in bright light

- Diminished contrast

- Changes in color perception (rare)

Posterior sub-capsular cataract

oo

About 20%

Objects no longer discernible

Patients with bilateral cataracts are practically blind and dependent on others in everyday life

Visual Effects Cataracts

Visual acuity

Progression

Peculiarities, glare, eyesight in twilight

Diagnosis and prognosis for vision

- Impairment is relatively late

- Increasing poor distance vision

- Near vision remains due to myopic effect of cataract

Slow

- Eyesight in twilight is often better than in daylight because the mydriasis in darkness allows light past the opacity

- Glare is less pronounced

- Monocular diplopia due to two focal points in the lens.

- Morphology by transillumination (Bruckner's test)

- Detailed diagnosis in slit-lamp examination

- Prediction of expected postoperative visual acuity: laser interference visual acuity testing

- Early loss of visual acuity

- Hyperopic effect of cataract compromises distance vision less than near vision

Rapid (temporary improvement in visual acuity due to stenopeic effect)

- Patient is severely hampered by glare (sun, snow, headlights). Patients typically prefer dark glasses and wide-brimmed hats.

- Marked improvement of vision in twilight and at night (nyctalopia)

- Early loss of visual acuity

- Near vision particularly affected, distance vision less so

Rapid

Visual acuity reduced to perception of light and dark; perception of hand movements in front of the eye at best.

All cataract forms will progress to a mature or hypermature form given enough time.

In intense light, patient will perceive gross movements and persons as silhouettes.

-

Leukocoria (white pupil) detectable with unaided eye. Slit-lamp permits differentiation. Retinoscopy to determine visual acuity is often inneffective with dense opacities.

— Nuclear cataract.

— Nuclear cataract.

Brunescent Cataract
Fig. 7.8 The nucleus of the lens has a yellowish brown color due to the pressure of peripheral lens fiber production.

Whereas changes in nuclear cataracts are due to hardening, cortical changes are characterized by increased water content. Several morphologic changes will be apparent upon slit-lamp examination with maximum mydri-

❖ Vacuoles: Fluid accumulations will be present in the form of small narrow cortical vesicles. The vacuoles remain small and increase in number.

❖ Water Fissures: Radial patterns of fluid-filled fissures will be seen between the fibers.

❖ Separation of the lamellae: Not as frequent as water fissures, these consist of a zone of fluid between the lamellae (often between the clear lamellae and the cortical fibers).

❖ Cuneiform cataract: This is a frequent finding in which the opacities radiate from the periphery of the lens like spokes of a wheel.

H Cortical cataracts progress more rapidly than nuclear cataracts. Visual acuity may temporarily improve during the course of the disease. This is due to a stenopeic effect as light passes through a clear area between two radial opacities.

Posterior subcapsular cataract. This is a special form of cortical cataract that begins in the visual axis. Beginning as a small cluster of granular opacities, this form of cataract expands peripherally in a disk-like pattern. As opacity increases, the rest of the cortex and the nucleus become involved (the usual spectrum of senile cataract).

asis:

Posterior subcapsular cataract leads to early, rapid, and severe loss of visual acuity. Near vision is usually significantly worse than distance vision (near-field miosis). Dilating eyedrops can improve visual acuity in this form of cataract.

Mature cataract. The lens is diffusely white due to complete opacification of the cortex. A yellow lens nucleus is often faintly discernible (Fig. 7.9). Where water content is increased, a lens with a mature cataract can swell and acquire a silky luster (intumescent cataract in which the capsule is under pressure). The increasing thickness of the lens increases the resistance of the pupil and with it the risk of angle closure glaucoma.

H Vision is reduced to perception of light and dark, and the interior of the eye is no longer visible. Cataract surgery is indicated to restore visual acuity.

Hypermature cataract. If a mature cataract progresses to the point of complete liquification of the cortex, the dense brown nucleus will subside within the capsule. Its superior margin will then be visible in the pupil as a dark brown silhouette against the surrounding grayish white cortex. The pressure in the lens capsule decreases. The contents of the limp and wrinkled capsular bag gravitate within the capsule. This condition, referred to as

— Mature cataract.

— Mature cataract.

Lens Nucleus The Eye

❖ There is diffuse, complete opacification of the lens. A brownish nucleus is faintlyvisible posterior to the cortical layer.

❖ Interior of the eye is no longer visible.

❖ Visual acuity is reduced to perception of light and dark.

❖ There is diffuse, complete opacification of the lens. A brownish nucleus is faintlyvisible posterior to the cortical layer.

❖ Interior of the eye is no longer visible.

❖ Visual acuity is reduced to perception of light and dark.

Morgagni's cataract, is the final stage in a cataract that has usually developed over the course of two decades. The approximate onset of the cataract can usually be inferred from such findings (Figs. 7.10a and b).

Prompt cataract extraction not only restores visual acuity but also prevents development of phacolytic glaucoma.

— Hypermature cataract.

— Hypermature cataract.

Brunescent Cataract
Fig. 7.10 a The brown nucleus has subsided in the liquified cortex.

b Histologic image obtained at autopsy shows the position of the subsided nucleus and the shrunken capsular bag.

When the lens capsule becomes permeable for liquified lens substances, it will lose volume due to leakage. The capsule will become wrinkled. The escaping lens proteins will cause intraocular irritation and attract macrophages that then cause congestion of the trabecular network (phacolyticglaucoma: see Secondary open angle glaucoma).

Emergency extraction of the hypermature cataract is indicated in phacolytic glaucoma to save the eye.

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