Metabolic disorders with corneal lesions

In metabolic diseases, any of the layers of the cornea can be involved in the pathological process.

Epithelial pathology

The corneal epithelium can be stained by toxic substances or become involved in the pathological process in some metabolic disorders.

• Chloroquine diphosphate and hydroxychlorine sulfate - ring-shaped turbidity.
• Amiodarone - characteristic curls, delicate point opacities.

Subepithelial pathology

These are subepithelial linear opacities that have a radial direction and are located in the upper half of the cornea. They are frequent companions of enteropathic acrodermatitis. These changes are characterized by a whorled shape. The process can be complicated by keratomalacia.

Symptoms of general pathology include nail dystrophy, digestive system disorders causing diarrhea and slow growth of the child.

As a therapeutic measure, a diet enriched with zinc is prescribed.

Stroma

Cystinosis is characterized by a disruption of the transport function of lysosomes and deposition of cysteine in them. Cysteine crystals, accumulating in the anterior parts of the stroma, cause thickening of the cornea, a disorder of its sensitivity, the development of superficial punctate keratopathy and recurrent erosions.

Associated pathology of cystinosis includes developmental delay, kidney disease, depigmentation of hair and skin, pigment retinopathy. Occurring in early childhood, cystinosis leads to renal failure and early death. Developing in adults, the disease does not affect the kidneys and is limited to corneal manifestations. Debuting in adolescents, cystinosis resembles the infantile form in clinical manifestations, but with the absence of developmental delay and skin changes.

Cysteamine is highly effective. In case of significant vision loss, penetrating keratoplasty is indicated.

Descemet's membrane

Wilson's disease is a hereditary disorder of copper metabolism. In this pathology, the level of copper transport protein is reduced in the blood serum, but increased in tissues. Apparently, the pathological gene is similar to the Menkes gene and is localized in the 3ql4.3 zone. The disorder often manifests itself as staining of the Descemet's membrane in the periphery of the cornea, especially intense at 12 and 6 o'clock.

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ]

Crystal deposition in the cornea

Crystal deposition in the cornea occurs in the following conditions:

1. cystinosis;
2. crystalline corneal dystrophy (Schnyder's dystrophy);
3. lecithin cholesterol acyltransferase deficiency;
4. uric acid crystals;
5. granular dystrophy and marginal dystrophy of Bietti;
6. multiple myeloma; monoclonal gammopathy;
7. calcium deposition;
8. corneal crystal deposition syndrome, myopathy, nephropathy;
9. tyrosinemia type II.

In the early stages of the disease, this symptom can only be established using gonioscopy.

Associated changes include:

• degeneration of the basal ganglia with the appearance of tremor;
• choreoathetosis;
• changes in the nervous system and psyche;
• staining of the renal tubules with the appearance of aminoaciduria;
• nodular form of cirrhosis.

Wilson's disease sometimes develops cataracts that resemble a sunflower (see Chapter 14). Treatment with penicillamine is not always effective, and a liver transplant may be required.

[ 6 ], [ 7 ], [ 8 ], [ 9 ]

Band keratopathy

Band keratopathy is the result of calcium impregnation of the Bowman's membrane. The underlying cause is usually a chronic inflammatory process or a systemic disease. The calcium deposit is initially localized within the palpebral fissure.

Band keratopathy is a common comorbidity of such systemic disorders as sarcoidosis, parathyroid disease, and multiple myeloma.

In many cases, band keratopathy is a companion to chronic inflammatory processes such as juvenile rheumatoid arthritis, Still's disease and sarcoidosis.

In this pathology, instillations of chelate preparations are effective. In some cases, band-like keratopathy develops in the final stages of phthisis of the eyeball.

Lecithin cholesterol acyltransferase deficiency

The disease is inherited in an autosomal recessive manner. In homozygous conditions and in premature infants, a central soft corneal opacity occurs, and in heterozygous conditions, arcus senilis is formed. Associated systemic diseases include renal failure, anemia, and hyperlipidemia.

[ 10 ], [ 11 ]

Arcuate corneal degeneration

Lipoid arcs of the cornea develop due to the deposition of phospholipids, low-density lipoproteins and triglycerides in the peripheral parts of the stroma. The arc is more often formed in young people and is associated with the following diseases:

• familial hypercholesterolemia (Friederickson syndrome, type II);
• familial hyperlipoproteinemia (type III);
• pathological processes associated with corneal diseases, such as vernal keratopathy or herpes simplex.
• primary lipoid degeneration of the cornea.

Arc formation can also occur in healthy individuals with normal plasma lipid levels.

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