Cataract complications

Association with primary eye disorders and systemic diseases

The development of complicated cataract is based on impaired composition of the intraocular fluid. Primary ophthalmological diseases acting as etiological factors include severe inflammatory and dystrophic processes. Classical examples include iridocyclitis, uncompensated glaucoma, Fuchs syndrome, retinal detachment, and retinitis pigmentosa.

In addition to purely ocular causes, lens opacification manifests against the background of systemic pathology, including dermatological and endocrine disorders. In clinical practice, diabetic cataract is increasingly common. The management of such patients requires a thorough medical history. The physician needs to assess:

• Duration of diabetes mellitus.
• Degree of disease control (blood glucose and glycated hemoglobin — HbA1c levels).
• Presence of concomitant arterial hypertension.
• Lipid metabolism parameters.
• Presence of macrovascular and microvascular complications.

It is also worth considering that pharmacotherapy for certain diseases inherently carries a risk of developing cataracts and glaucoma. Other side effects of treatment include weight gain, development of diabetes mellitus, arterial hypertension, peptic ulcer disease, osteoporosis, and psychiatric disorders.

External factors: trauma, radiation, and toxins

The lens is highly sensitive to adverse environmental factors. Mechanical, thermal, radiation, and chemical impacts rapidly lead to pathological changes.

Traumatic cataract In trauma, not only opacification of the structure is observed, but also displacement of the lens (forming a luxation or subluxation). The biomechanics of this process are associated with complete or partial rupture of the Zonule of Zinn. It is important to note that in penetrating wounds of the eyeball, opacification develops significantly faster compared to blunt trauma.

Radiation cataract Damaging effects are caused by several types of radiation:

• Infrared radiation: invisible IR rays are actively absorbed by the lens. This is a common occupational hazard for workers in hot shops of the steelmaking industry.
• Ionizing radiation: X-rays and radium rays, neutrons, protons, and nuclear fission elements exert a powerful destructive effect (a historical example is cataracts in survivors of the Hiroshima and Nagasaki bombings).

The lens of children and young adults has a higher radiation sensitivity compared to older patients. At the same time, rays of the visible spectrum (wavelength 380–760 nm) pass freely through the optical media without damaging them.

Toxic cataract The disease develops in systemic poisoning of the body. The cataractogenic effect of chemical agents such as naphthalene, thallium, trinitrotoluene, dinitrophenol, and various nitro paints has been proven.

Relationship with secondary glaucoma

Lens pathologies and surgeries for its removal are closely associated with the risk of developing secondary glaucomas. The elevation of intraocular pressure (IOP) in these cases occurs primarily due to impaired outflow of intraocular fluid.

Traumatic glaucoma May manifest at various times—from the early period to several years after injury (e.g., in traumatic recession of the anterior chamber angle). Among the causes of IOP elevation are:

1. Blockage of the drainage system by a displaced lens or its breakdown products.
2. Intraocular hemorrhages (hemophthalmos, hyphema).
3. Chemical or radiation damage to blood vessels.
4. Consequences of traumatic uveitis.

Postoperative glaucoma Acts as a direct complication of surgical intervention. The elevation of IOP can be temporary or permanent. Most commonly occurs after cataract extraction (aphakic glaucoma), keratoplasty, or retinal detachment surgery.

Dystrophic and neoplastic glaucoma The dystrophic form is characteristic of retinal detachment, systemic amyloidosis, extensive hemorrhages (hemolytic glaucoma), and iridocorneal endothelial syndrome. In the latter, the inadequacy of the corneal endothelium leads to iris atrophy and the formation of a thin membrane. Cicatricial contraction of this membrane causes partial obliteration of the anterior chamber angle (ACA), pupil deformation, and stretching of the iris with cleft formation. Neoplastic glaucoma develops due to blockage of the ACA by a tumor node (melanoblastoma, retinoblastoma) or the deposition of tumor tissue breakdown products in the trabecular meshwork. In orbital neoplasms, IOP rises due to direct pressure on the eyeball and increased pressure in the veins.

Principles of treatment

The primary and most effective method of treatment for cataracts is surgical intervention.

Conservative therapy is considered exclusively as a forced measure. It is indicated only in situations where the patient's severe general somatic condition categorically precludes surgery. The essence of the conservative approach is the regular instillation of specialized eye drops aimed at locally improving metabolic processes in the lens tissues.

In the development of concomitant glaucomas, treatment involves targeted action on key pathogenetic links for sustained reduction of intraocular pressure.

Class and exam questions

What else to study on this topic

• Pathogenesis of iridocorneal endothelial syndrome
• Specifics of monitoring patients with diabetic cataract
• Mechanisms of neoplastic glaucoma development
• Differences in the effects of infrared and ionizing radiation on the eye

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.