Fuchs Corneal Endothelial Dystrophy

Introduction to Fuchs corneal endothelial malnutrition Fuchsendothelialdystrophy, also known as the corneal cornea (corneaguttata), is a common phenomenon that increases significantly with age. In many patients with keratoconus, other aspects of the cornea are normal and do not affect vision. A small number of patients with corneal stroma and epithelial edema can cause significant loss of vision. basic knowledge The proportion of illness: 0.03% Susceptible people: no special people Mode of infection: non-infectious Complications: glaucoma

Fuchs corneal endothelial dystrophy etiology

(1) Causes of the disease

The disease has a certain hereditary nature, the genetic pattern is not very clear, some cases have been confirmed as autosomal dominant inheritance, the cause is unknown, may be multi-faceted, and some unrecognized factors interfere with the structure of corneal endothelial cells The function ultimately leads to decompensation of endothelial pump function.

In addition to the sporadic case of the disease, it is an autosomal dominant genetic disease. In 2001, Biswas et al. performed a genome analysis on a family, and found that type VIII collagen Alpha2 (COL8A2) located in the short arm 1p34.3-p32 of chromosome 1. The Q455K missense mutation occurred in the gene, which may interfere with the terminal differentiation of corneal endothelial cells by type VIII collagen, disrupting the structure and function of corneal endothelial cells, resulting in abnormal basement membrane and fibrillar collagen products. Drops of sputum, sputum sputum further damage the corneal endothelial cells, and finally cause degeneration of corneal pump function and anti-apoptotic function, resulting in loss of useful vision.

Primary dystrophic corneal endothelial cells may cause collagen deposition behind the posterior elastic membrane. Simple drop corneal histology may be a sputum or sputum biological appearance, and in other cases may be local collagen deposition, extra coverage of the substrate. Membrane or a uniformly thickened posterior collagen layer. However, viral particles were found on a case of Fuchs endothelial dystrophy corneal specimens, suggesting a possible etiology.

(two) pathogenesis

Although the underlying abnormalities of the endothelium in Fuchs endothelial dystrophy are still unclear, the pathogenesis seen in clinical practice has the following aspects:

1. Increased collagen production: mostly behind the posterior elastic layer and under the epithelium. As with many other corneal diseases, Fuchs dystrophic abnormal endothelial cells produce excess collagen, including abnormal collagen, and the basement membrane and layers are loose. Fibrillar collagen, subepithelial connective tissue comes from fibroblasts that migrate from the limbus or matrix, but some of which may also come from the epithelium.

2. Endothelium barrier function and pump function reduction: It can occur at the same time that the endothelial degeneration is destroyed, the connection of the apical space of the cell is destroyed, and the aqueous humor passes through the endothelial barrier into the stromal and epithelium, which cannot be pumped due to the diseased endothelium. Out, and the epithelial barrier prevents it from escaping from the front of the cornea, causing edema of the cornea. In the late stage of the lesion, the formation of the scar under the epithelium prevents the liquid from entering the epithelium, the scar formation of the matrix makes the cornea no longer thick, and the posterior collagen tissue makes the posterior toughness of the cornea Increased and difficult to swell, so the corneal structure is tighter than before, the patient feels more comfortable, the density of Na+-K+ pump (Na+-K+ATPase) in corneal endothelial cells increased significantly in the early stage of the disease, and the Na+-K+ pump developed with the disease. The density gradually decreases and eventually the pump function is completely lost.

3. Glaucoma pathogenesis

(1) The effect of intraocular pressure on corneal endothelium: There are controversies about the association between glaucoma and striated cornea and Fuchs endothelial dystrophy. One of the reasons is that elevated intraocular pressure often leads to secondary changes in corneal endothelium and decreased endothelial cell density. Seen in: open angle glaucoma, angle-closure glaucoma and some secondary glaucoma, but the degree of corneal endothelium changes is not always consistent with the degree of elevated intraocular pressure, suggesting that other factors (such as age or anterior uveitis) will It affects the relationship between glaucoma and changes in corneal endothelium. Therefore, the above factors must be considered when evaluating the relationship between glaucoma and the drip cornea and Fuchs endothelium.

(2) Droplet cornea and aqueous humor outflow: patients with drip cornea have a higher incidence of abnormal aqueous humor fluence, but subsequent studies have confirmed that the mean value of aqueous humor flow coefficient in the drip corneal group is not statistically different from the normal group. There was no correlation between the extent of keratopathy and the fluency coefficient of aqueous humor. The comparison between the smear corneal group and the non-drop corneal matching group showed that the former had a lower mean intraocular pressure.

(3) Fuchs endothelial dystrophy and glaucoma: The connection between open-angle glaucoma and Fuchs endothelial dystrophy remains unclear. It was previously estimated that 10% to 15% of Fuchs endothelial dystrophy patients have open-angle glaucoma, but in Fuchs endothelial dystrophy There was no genetic overlap between Fuchs endothelial dystrophy and primary open angle glaucoma.

Patients with shallow anterior chamber and Fuchs endothelial dystrophy are prone to angle-closure glaucoma. Obviously, this is due to the thickening of the cornea and eventually the closure of the angle. Some previous authors have proposed angle-closure glaucoma, especially with iris. Atrophic acute angle-closure glaucoma has a high incidence of keratoconus. It has also been suggested that the anterior chamber of patients with drip corneal or Fuchs endothelial dystrophy has a shallower anterior axis, but another study suggests that this is a non-related abnormal condition. Exist, may have an impact on each other.

Fuchs corneal endothelial dystrophy prevention Pay attention to rest, work and rest, life in an orderly manner, and maintaining an optimistic, positive and upward attitude towards life can be of great help in preventing diseases.

Fuchs corneal endothelial dystrophy complications Complications glaucoma

Corneal degeneration, decompensation and glaucoma.

Fuchs corneal endothelial dystrophy symptoms Common symptoms Central corneal posterior... IOP increased drip cornea

Clinical change

(1) corneal changes: Fuchs endothelial dystrophy has a typical silvery appearance in the posterior part of the cornea, usually called "cornea guttata", the clinical course is usually 10 to 20 years, can be divided into 3 phases, in the first phase, the patient is asymptomatic There are irregular spots of mites and dusty pigment spots in the central part of the cornea. After that, the posterior elastic layer can be gray and thickened. In the second stage, the corneal stroma and epithelium are edematous, and the patient is unclear. And the glare, matrix edema initially appears in front of the rear elastic layer and close to the front elastic layer, after which all the matrix gradually becomes frosted glass, and liquid-like cracks appear in the swelling, so that the rear elastic layer forms wrinkles, epithelium The edema initially causes the surface of the cornea to be pigskin-like or sprinkled with small water droplets, and then gradually forms large oval or curved epithelial vesicles, causing paroxysmal pain when ruptured, and visual acuity declines due to matrix mixing and irregular astigmatism. When you wake up, your eyesight is especially poor. Because of the decrease in tear evaporation during sleep, the permeability is reduced, resulting in increased corneal edema. In stage 3, connective tissue under the epithelium appears, while epithelial edema is reduced. Pipe has dropped to poor identified only manually, but consciously comfortable than before, this period can be some complications, such as epithelial shedding, ulcer caused by microbes, the peripheral portion of angiogenesis and increased intraocular pressure.

Examination of the corneal lesions under the slit lamp begins at the central part and gradually expands to the periphery. The following changes can occur from the posterior corneal to the front: corneal punctate degeneration, thickening and wrinkling of the posterior elastic layer; endothelial pigmentation; stromal edema, subepithelial Neovascularization of connective tissue and peripheral surface; epithelial edema and large vesicles, prominent changes are the appearance of beaten silver in the posterior part of the cornea, changing like ICE syndrome, but rough, most significant pathology The histological changes are located behind the posterior elastic layer, and the endothelial cells produce new collagen tissue. The clinical manifestation is that the posterior elastic layer is thickened, and the posterior elastic layer and the new collagen tissue form a multi-layer structure, which is colored and phased after PAS staining. And produce a gray spiral pattern that is clinically seen.

(2) combined with glaucoma: Fuchs endothelial epithelial dystrophy can be associated with two types of glaucoma: open-angle glaucoma and angle-closure glaucoma, estimated incidence of 10% to 15%, the mechanism of open angle glaucoma may be related to trabecular endothelial Involved in the network, the shallow anterior chamber and Fuchs malnutrition, the corneal parenchyma gradually thickened, resulting in the iris corneal angle completely closed, and acute angle-closure glaucoma occurred. In many cases, the angle closure occurred before corneal edema occurred. These cases were glaucoma. The mechanism is related to hyperopia and shallow anterior chamber, and may have some connection with Fuchs malnutrition. Fuchs malnutrition is different from ICE syndrome in the mechanism of glaucoma.

Reports on corneal spots and Fuchs endothelial dystrophy with glaucoma are ambiguous. In fact, patients with elevated intraocular pressure can often undergo changes in the corneal endothelium. In patients with glaucoma, corneal endothelial cell density and morphology are also Changes can occur, the degree of endothelial dystrophy is not always related to the degree of intraocular pressure, other factors can also affect glaucoma and corneal endothelium changes, such as anterior uveitis, glaucoma-ciliary inflammatory syndrome, etc. will also affect the cornea Changes in endothelial morphology, as well as normal human corneal endothelium, also change with age, and any damage between glaucoma and corneal endothelium must be considered.

2. Clinical staging

The course of the disease is divided into three phases, up to 20 years or longer.

(1) Phase 1 [Cornea guttata period]: This period of patients has no symptoms. When using the slit lamp direct illumination method, the posterior surface of the central part of the cornea is visible. A plurality of small, guttata protruding backwards, slightly bluish; when illuminated by the posterior illumination, it is shown on the surface of the endothelium, with scattered, round, refractive golden depressions; When the cut wide-band illumination method is used, it can be seen that the Descemet film is thickened in gold foil and has some irregular gray turbid spots on it. When using endoscopic examination, some black areas appear in the normal mosaic form of endothelial cells. The appearance of corneal sputum does not mean that it has the diagnostic signs of this disease, because in most cases it does not develop Fuchs corneal dystrophy, but only the product of senile corneal endothelial cell degeneration, corneal drops can also be an early manifestation of the disease. As the disease progresses, the number of sputum sputum can gradually increase, merge with each other and expand to the periphery, invading the entire cornea, the function of the endothelial cell biopump once funeral Lost, then enter the second phase of the disease.

(2) Phase 2 (substantial and epithelial edema, ie primary corneal decompensation): In this period, the patient's vision decreased, pain appeared and progressively increased, when corneal endothelial cell density decreased, corneal endothelial biopump function After the abnormality, corneal edema can be seen under the slit lamp from the parenchyma layer of the Descemet membrane. The Descemet membrane appears wrinkles, the corneal thickness increases, the parenchyma layer is slightly opaque to the ground glass, and then the corneal epithelium is microcystic edema and the corneal surface is uneven. The patient often has poor vision in the early morning. During the day, the water on the anterior surface of the cornea is evaporated, the epithelial edema is improved, and the visual acuity is improved. When the intraocular pressure is increased, the epithelial edema is intensified, and the corneal epithelium and subepithelial edema can be merged into vesicles. Large bubbles, severe pain in the eyes after breaking the big bubble.

(3) Stage 3 (scar formation period): Long-term edema of the cornea can lead to corneal angiogenesis, and connective tissue layer diffusely formed under the epithelium. Repeated episodes of large bubble rupture are more likely to form scars, and scars after corneal scar formation. Decreased, epithelial edema is relieved, pain is relieved, but vision is more diminished.

Fuchs corneal endothelial dystrophy

1. Iris keratoscopy: you can understand the involvement of trabecular meshwork.

2. Corneal endoscopic surface microscopy: can understand the posterior elastic layer and corneal endothelium lesions.

3. Pathological examination: the number of corneal endothelial cells is reduced, thinning, Descemet membrane thickening and dripping sputum behind it, this sputum can protrude into the anterior chamber, or can be buried in the posterior part of the Descemet membrane, the parenchyma Edema, widening of interlaminar space, disordered collagen arrangement, increased corneal cells, complete Bowman layer, focal rupture in some areas, connective tissue invasion at the break, and extension to epithelial cell layer, epithelial basal cell edema, cells The gap is enlarged, and there is a connective tissue layer between the epithelial basement membrane and the Bowman layer. The focal thickening of the new collagen tissue forms scattered sputum or sputum, that is, the corneal degeneration point, and there are four manifestations:

1 simple condyle into the anterior chamber;

2 multi-layer layers;

3 piles of rafts in a multi-layer structure;

4 Innocent multi-layer structure, some neoplasms form block-like protrusions, and some are mushroom-like.

4. Scanning electron microscopy: It can be seen that the neoplasms squeeze the endothelial cell into a dumbbell shape or a prism shape, which makes the covered endothelial cells thinner and makes the cell boundary irregular, destroys the integrity of the endothelial mosaic pattern, and increases the endothelial cells. Black spots of varying sizes can occur, exceeding the edge of their cells, and even after losing their typical hexagonal structure, they usually cover the posterior surface of the cornea intact.

5. Transmission electron microscopy: It shows that some cytoplasm of endothelial cells have vacuoles, nuclear shrinkage and other degeneration phenomena; some contain melanin particles; and some endothelial cells have morphological characteristics of fibroblasts (endoplasmic reticulum increases, cytoplasm is full) Microfilaments and ribosomes); others have characteristics similar to epithelial cells (surface microvilli, intercellular desmosomes), the most prominent change is the diffuse thickening of the Descemet membrane, which is characterized by no anterior strip Significantly change, the posterior non-belt layer is thin or missing, and behind it is a strip of layer composed of collagen basement membrane material, which is densely thickened in some areas and protrudes backwards into drip, drip and Filaments and amorphous substances sometimes appear between endothelial cells.

Diagnosis and diagnosis of Fuchs corneal endothelial dystrophy

According to the clinical manifestations, combined with the characteristic changes of the cornea, the possibility of the disease should be considered, but attention should be paid to the identification.

Differential diagnosis

1. ICE syndrome: In Fuchs endothelial dystrophy is a bilateral onset, completely without the angle of the ICE syndrome and iris changes. More common in women aged 20 to 30 years, single eye disease.

2. Corneal edema.

3. Increased intraocular pressure.

4. The iris shrinks, the pupil is deformed, and the iris forms a hole.

5. The corner of the room is stuck.

6. PPMD: In the Fuchs endothelial dystrophy, there is rarely a bridge-like iris corneal adhesion, iris changes and PPMD-specific irregular corneal posterior changes.

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