Fuchs' dystrophy
Encyclopedia
Fuchs' dystrophy, also known as Fuchs' endothelial dystrophy, is a slowly progressing cornea
l disease
that usually affects both eye
s and is slightly more common in women than in men. Although doctors can often see early signs of Fuchs' dystrophy
in people in their 30s and 40s, the disease rarely affects vision until people reach their 50s and 60s.
The condition was first described by Austria
n Ernst Fuchs
(1851–1930), after whom it is named.
also becomes edematous, resulting in more severe visual impairment. Focal areas or blisters of epithelial edema ("bullae") may be particularly painful.
The inheritance of FED is autosomal dominant with genetic and environmental modifiers such as increased prevalence in the elderly and in females. Endothelial cell loss may be aggravated or accelerated by intraocular trauma or surgery. A common scenario involves excessive corneal swelling or edema following cataract surgery or other types of ocular surgery. Hence, patients with a history of Fuchs' dystrophy may be at a greater risk of corneal edema after ocular surgery as they have fewer functioning endothelial cells.
FED is classified into 4 stages, from early signs of guttae formation to end-stage subepithelial scarring. Diagnosis is made by biomicroscopic examination; other modalities, such as corneal pachymetry
, confocal biomicroscopy, and specular microscopy can be used in conjunction.
Exact pathogenesis is unknown but factors include endothelial cell apoptosis, sex hormones, inflammation, and aqueous humor flow and composition. Mutations in collagen VIII
, a major component of Descemet’s membrane secreted by endothelial cells, have been linked to the early-onset FED.
Genes include:
will awaken with blurred vision that will gradually clear during the day. This occurs because the cornea is normally thicker in the morning; it retains fluids during sleep that evaporate in the tear film while we are awake. As the disease worsens, this swelling will remain constant and reduce vision throughout the day.
es. In using a hairdryer, the patient is instructed to hold a hairdryer at an arm's length or directed across the face, to dry out the epithelial blisters. This can be done two or three times a day. Definitive treatment, however, (especially with increased corneal edema) is surgical in the form of corneal transplantation, or penetrating keratoplasty (PKP).
Since 1998, new surgical modalities in the treatment of FED have been developed by Melles et al. in The Netherlands. These procedures, called posterior lamellar keratoplasty or endothelial keratoplasty, have been popularized as deep lamellar endothelial keratoplasty (DLEK) and Descemet’s stripping with endothelial keratoplasty (DSEK). DLEK and DSEK avoid the surgical complications of PKP such as wound dehiscence and infections and high postoperative astigmatism. Since 2004, DSEK has become the dominant procedure because it is technically much easier for the surgeon compared to DLEK or PKP. Improved surgical instrumentation for DSEK, such as a DSEK graft injector will become available shortly (2008). This could allow faster recovery for patients because of the ability to perform DSEK through very small (3 mm) sutureless incisions.
Recently, endothelial keratoplasty has been further refined to Descemet Membrane Endothelial Keratoplasty (DMEK), in which only a donor Descemet membrane and its endothelium is transplanted. With DMEK, 90% of cases achieve a best spectacle corrected visual acuity 20/40 or better, and 60% of cases 20/25 or better within 1–3 months.
More speculative future directions in the treatment of FED include in vitro expansion of human corneal endothelial cells for transplantation, artificial corneas and genetic modification.
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
l disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
that usually affects both eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
s and is slightly more common in women than in men. Although doctors can often see early signs of Fuchs' dystrophy
Corneal dystrophy (human)
Human corneal dystrophy is a group of disorders, characterised by a noninflammatory, inherited, bilateral opacity of the transparent front part of the human eye called the cornea...
in people in their 30s and 40s, the disease rarely affects vision until people reach their 50s and 60s.
The condition was first described by Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
n Ernst Fuchs
Ernst Fuchs (doctor)
Ernst Fuchs was an Austrian ophthalmologist and physician best known for his contribution to description and identification of Fuchs heterochromic iridocyclitis in 1906, Fuchs's dystrophy, and his contributions in the field of ophthalmology including but not limited to Fuchs spot...
(1851–1930), after whom it is named.
Etiology
Fuchs’ endothelial dystrophy (FED) is a degenerative disorder of the corneal endothelium with accumulation of focal excrescences called guttae and thickening of Descemet’s membrane, leading to corneal edema and loss of vision. Corneal endothelial cells are the major “pump” cells of the cornea to allow for stromal clarity. In FED, Descemet’s membrane is grossly thickened with accumulation of abnormal wide-spaced collagen and numerous guttae. Corneal endothelial cells in end-stage FED are reduced in number and appear attenuated, causing progressive stromal edema. Progressive endothelial cell loss causes relative influx of aqueous humor into the cornea, leading to swelling (corneal stromal edema), which results in distorted vision. Eventually, the epitheliumEpithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
also becomes edematous, resulting in more severe visual impairment. Focal areas or blisters of epithelial edema ("bullae") may be particularly painful.
The inheritance of FED is autosomal dominant with genetic and environmental modifiers such as increased prevalence in the elderly and in females. Endothelial cell loss may be aggravated or accelerated by intraocular trauma or surgery. A common scenario involves excessive corneal swelling or edema following cataract surgery or other types of ocular surgery. Hence, patients with a history of Fuchs' dystrophy may be at a greater risk of corneal edema after ocular surgery as they have fewer functioning endothelial cells.
FED is classified into 4 stages, from early signs of guttae formation to end-stage subepithelial scarring. Diagnosis is made by biomicroscopic examination; other modalities, such as corneal pachymetry
Corneal pachymetry
Corneal pachymetry is the process of measuring the thickness of the cornea using contact methods, such as ultrasound and confocal microscopy , or noncontact methods such as optical biometry with a single Scheimpflug camera , or a Dual Scheimpflug camera , or Optical Coherence Tomography and online...
, confocal biomicroscopy, and specular microscopy can be used in conjunction.
Exact pathogenesis is unknown but factors include endothelial cell apoptosis, sex hormones, inflammation, and aqueous humor flow and composition. Mutations in collagen VIII
COL8A2
Collagen alpha-2 chain is a protein that in humans is encoded by the COL8A2 gene. Mutations of the gene are linked to posterior polymorphous dystrophy type 2.-Further reading:...
, a major component of Descemet’s membrane secreted by endothelial cells, have been linked to the early-onset FED.
Genes include:
| Type | OMIM | Gene | Locus |
|---|---|---|---|
| FECD1 | COL8A2 COL8A2 Collagen alpha-2 chain is a protein that in humans is encoded by the COL8A2 gene. Mutations of the gene are linked to posterior polymorphous dystrophy type 2.-Further reading:... |
1p34.3-p32.3 | |
| FECD4 | SLC4A11 SLC4A11 Sodium bicarbonate transporter-like protein 11 is a protein that in humans is encoded by the SLC4A11 gene.-Further reading:... |
20p13-p12 | |
| FECD6 | ZEB1 ZEB1 Zinc finger E-box-binding homeobox 1 is a protein that in humans is encoded by the ZEB1 gene.TCF8 encodes a human zinc finger transcription factor that represses T-lymphocyte-specific IL2 gene expression by binding to a negative regulatory domain 100 nucleotides 5-prime of the IL2 transcription... |
10p11.2 |
Signs and symptoms
At first, a person with Fuchs' dystrophyCorneal dystrophy (human)
Human corneal dystrophy is a group of disorders, characterised by a noninflammatory, inherited, bilateral opacity of the transparent front part of the human eye called the cornea...
will awaken with blurred vision that will gradually clear during the day. This occurs because the cornea is normally thicker in the morning; it retains fluids during sleep that evaporate in the tear film while we are awake. As the disease worsens, this swelling will remain constant and reduce vision throughout the day.
Treatment
Medical management includes topical hypertonic saline, the use of a hairdryer to dehydrate the precorneal tear film, and therapeutic soft contact lensContact lens
A contact lens, or simply contact, is a lens placed on the eye. They are considered medical devices and can be worn to correct vision, for cosmetic or therapeutic reasons. In 2004, it was estimated that 125 million people use contact lenses worldwide, including 28 to 38 million in the United...
es. In using a hairdryer, the patient is instructed to hold a hairdryer at an arm's length or directed across the face, to dry out the epithelial blisters. This can be done two or three times a day. Definitive treatment, however, (especially with increased corneal edema) is surgical in the form of corneal transplantation, or penetrating keratoplasty (PKP).
Since 1998, new surgical modalities in the treatment of FED have been developed by Melles et al. in The Netherlands. These procedures, called posterior lamellar keratoplasty or endothelial keratoplasty, have been popularized as deep lamellar endothelial keratoplasty (DLEK) and Descemet’s stripping with endothelial keratoplasty (DSEK). DLEK and DSEK avoid the surgical complications of PKP such as wound dehiscence and infections and high postoperative astigmatism. Since 2004, DSEK has become the dominant procedure because it is technically much easier for the surgeon compared to DLEK or PKP. Improved surgical instrumentation for DSEK, such as a DSEK graft injector will become available shortly (2008). This could allow faster recovery for patients because of the ability to perform DSEK through very small (3 mm) sutureless incisions.
Recently, endothelial keratoplasty has been further refined to Descemet Membrane Endothelial Keratoplasty (DMEK), in which only a donor Descemet membrane and its endothelium is transplanted. With DMEK, 90% of cases achieve a best spectacle corrected visual acuity 20/40 or better, and 60% of cases 20/25 or better within 1–3 months.
More speculative future directions in the treatment of FED include in vitro expansion of human corneal endothelial cells for transplantation, artificial corneas and genetic modification.
See also
- Fuchs heterochromic iridocyclitisFuchs heterochromic iridocyclitisFuchs heterochromic iridocyclitis is a chronic unilateral iridocyclitis appearing with the triad of heterochromia, predisposition to cataracts and glaucoma, and keratitic precipitates on the posterior corneal surface...
(a disease of the irisIris (anatomy)The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
) - Ocular straylightOcular straylightOcular straylight is the unwanted effect of light spreading as seen by human eyes, and caused by the eye itself, not by external factors. It is most easily visualized as the radiation seen spreading from a bright light source against a dark background. The typical practical example is an opposing...