Decreased corneal sensation

Introduction Decreased corneal sensation causes a reduction in blinking and affects tear film remodeling. On the one hand, the loss of corneal sensation reduces the nerve impulses transmitted by the cornea through the reflex arc to the brain system, resulting in a decrease in the nerve impulses transmitted to the lacrimal gland and a decrease in the amount of tear-based secretion. On the other hand, after the corneal sensation subsides, because the blink frequency is positively correlated with the corneal perception, the corresponding blink frequency is reduced, and the blinking is the basis of tear film reconstruction: each blinking, the blinking action will be tear mucin Evenly distributed on the surface of the cornea, the aqueous layer and the lipid layer are evenly distributed on the surface of the cornea to complete the tear film reconstruction. The decrease in the number of blinks will lead to enhanced evaporation of the tears, affecting the uniform distribution of mucin in the ocular surface, so that the aqueous layer and the lipid layer do not adhere well, affecting tear film reconstruction. Corneal sensation reduction is a clinical symptom of exposed keratitis. Exposure keratitis (exposure keratitis) is common in various lesions of cleft palate, resulting in corneal exposure and blink dyskinesia, tears can not normally wet the cornea and corneal epithelial damage.

Cause

1. The state of the eye caused by the thyroid gland, pituitary gland, or orbital tumor.

2, scarring valgus, orbital osteomyelitis and bone defects or scarring adhesions, sacral tendon palsy, lifting the diaphragmatic tendon caused by dysfunction.

an examination

Related inspection

Corneal sensation test for corneal reflex examination

Combined with medical history, the corneal lesions were examined by general corneal visual inspection, photogrammetry, Placido disc examination, and corneal staining.

Due to the exposure of the corneal surface, the tears evaporate too fast, the corneal epithelium is dry, blurred, necrotic, shedding, ulceration or corneal epithelial keratinosis, accompanied by matrix infiltration and turbidity. If the degree of cleft palate is less severe and the eyeball is upturned (Bell phenomenon) when closed eyes, only one-third or less of them are exposed, corneal damage is also limited to this part, due to decreased corneal sensation Invasion of foreign bodies can not reflect and block, so it is easy to damage, and even secondary bacterial and fungal infections.

In the case of incomplete closure of the eyelids, the exposed corneal surface becomes dry due to the acceleration of evaporation of the liquid evaporating liquid, resulting in severe infiltration and ulceration. This disease has no secondary infection and is generally only grayish white with no sharp changes. There is no suppuration.

Differential diagnosis

1 Claudication keratitis: mainly caused by bacteria with strong virulence. Pneumococcal, hemolytic or Streptococcus mutans, Neisseria gonorrhoeae, Bacillus subtilis, Staphylococcus aureus, etc. can cause disease. Before the onset of the disease, there is often a history of corneal surface trauma, or foreign matter such as dust. Systemic malnutrition and weakness are also prone to disease; patients with chronic dacryocystitis are prone to this disease.

2 Pseudomonas aeruginosa keratitis: This disease is caused by Pseudomonas aeruginosa directly invading the cornea. Pseudomonas aeruginosa is very toxic, but its invasiveness is very weak. It must pass through the damaged epithelium to invade the corneal tissue and cause infection. Therefore, various corneal trauma, keratitis, corneal softening, etc. can be the cause of infection.

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