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Epithelial Basement Membrane Dystrophy
Epithelial basement membrane dystrophy (EBMD) is a disorder of the eye that can cause pain and dryness. EBMD, also known as map-dot-fingerprint dystrophy and Cogan microcystic epithelial dystrophy, is a corneal epithelial disease that may result in recurrent corneal erosions, irregular corneal astigmatism, and decreased vision. It is sometimes included in the group of corneal dystrophies. It diverges from the formal definition of corneal dystrophy since it is non-familial in most cases. It also has a fluctuating course, while for a typical corneal dystrophy the course is progressive. When it is considered part of this group, it is the most common type of corneal dystrophy. Signs and symptoms Patients may complain of severe problems with dry eyes, or with visual obscurations. It can also be asymptomatic, and only discovered because of subtle lines and marks seen during an eye exam. EBMD is a bilateral anterior corneal dystrophy characterized by grayish epithelial fingerprint ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmology
Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medical degree, a doctor specialising in ophthalmology must pursue additional postgraduate residency training specific to that field. In the United States, following graduation from medical school, one must complete a four-year residency in ophthalmology to become an ophthalmologist. Following residency, additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology. Ophthalmologists prescribe medications to treat ailments, such as eye diseases, implement laser therapy, and perform surgery when needed. Ophthalmologists provide both primary and specialty eye care—medical and surgical. Most ophthalmologists participate in academic research on eye diseases at some point in their training and many inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recurrent Corneal Erosion
Recurrent corneal erosion (RCE) is a disorder of the eyes characterized by the failure of the cornea's outermost layer of epithelial cells to attach to the underlying basement membrane ( Bowman's layer). The condition is excruciatingly painful because the loss of these cells results in the exposure of sensitive corneal nerves. This condition can often leave patients with temporary blindness due to extreme light sensitivity (photophobia). Signs and symptoms Symptoms include recurring attacks of severe acute ocular pain, foreign-body sensation, photophobia (i.e. sensitivity to bright lights), and tearing often at the time of awakening or during sleep when the eyelids are rubbed or opened. Signs of the condition include corneal abrasion or localized roughening of the corneal epithelium, sometimes with map-like lines, epithelial dots or microcysts, or fingerprint patterns. An epithelial defect may be present, usually in the inferior interpalpebral zone. Cause Most cases of recurrent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astigmatism
Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. The lens and cornea of an eye without astigmatism are nearly spherical, with only a single radius of curvature, and any refractive errors present can be corrected with simple glasses. In an eye with astigmatism, either the lens or the cornea is slightly egg-shaped, with higher curvature in one direction than the other. This gives distorted or blurred vision at any distance and requires corrective lenses that apply different optical powers at different rotational angles. Astigmatism can lead to symptoms that include eyestrain, headaches, and trouble driving at night. Astigmatism often is present at birth, but can change or develop later in life. If it occurs in early life and is left untreated, it may result in amblyopia. The cause of astigmatism is unclear, although it is believed to be partly related to genetic factors. The underlying mechanism involves an irregular c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corneal Dystrophy
Corneal dystrophy is a group of rare hereditary disorders characterised by bilateral abnormal deposition of substances in the transparent front part of the eye called the cornea. Signs and symptoms Corneal dystrophy may not significantly affect vision in the early stages. However, it does require proper evaluation and treatment for restoration of optimal vision. Corneal dystrophies usually manifest themselves during the first or second decade but sometimes later. It appears as grayish white lines, circles, or clouding of the cornea. Corneal dystrophy can also have a crystalline appearance. There are over 20 corneal dystrophies that affect all parts of the cornea. These diseases share many traits: * They are usually inherited. * They affect the right and left eyes equally. * They are not caused by outside factors, such as injury or diet. * Most progress gradually. * Most usually begin in one of the five corneal layers and may later spread to nearby layers. * Most do not affect ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Eyes
Dry eye syndrome, also known as keratoconjunctivitis sicca, is the condition of having dry eyes. Symptoms include dryness in the eye, irritation, redness, discharge, blurred vision, and easily fatigued eyes. Symptoms range from mild and occasional to severe and continuous. Dry eye syndrome can lead to blurred vision, instability of the tear film, increased risk of damage to the ocular surface such as scarring of the cornea, and changes in the eye including the neurosensory system. Dry eye occurs when either the eye does not produce enough tears or when the tears evaporate too quickly. This can be caused by age, contact lens use, meibomian gland dysfunction, pregnancy, Sjögren syndrome, vitamin A deficiency, omega-3 fatty acid deficiency, LASIK surgery, and certain medications such as antihistamines, some blood pressure medication, hormone replacement therapy, and antidepressants. Chronic conjunctivitis such as from tobacco smoke exposure or infection may also lea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dominance (genetics)
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second is called recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance, such as incomp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TGFBI
Transforming growth factor, beta-induced, 68kDa, also known as TGFBI (initially called BIGH3, BIG-H3), is a protein which in humans is encoded by the ''TGFBI'' gene, locus 5q31. Function This gene encodes an arginylglycylaspartic acid, RGD-containing protein that binds to type I, II and IV collagens. The RGD motif is found in many extracellular matrix proteins modulating cell adhesion and serves as a ligand recognition sequence for several integrins. This protein plays a role in cell-collagen interactions and may be involved in endochondral ossification, endochondrial bone formation in cartilage. The protein is induced by transforming growth factor-beta and acts to inhibit cell adhesion. Clinical significance Mutations of the gene cause several forms of corneal dystrophy (human), corneal dystrophies. References Further reading * * * * * * * * * * * * * * * * * * * * * Extracellular matrix proteins {{gene-5-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornea
The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea Refraction, refracts light, accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43 dioptres. The cornea can be reshaped by surgical procedures such as LASIK. While the cornea contributes most of the eye's focusing power, its Focus (optics), focus is fixed. Accommodation (eye), Accommodation (the refocusing of light to better view near objects) is accomplished by changing the geometry of the lens. Medical terms related to the cornea often start with the prefix "''wikt:kerat-, kerat-''" from the Ancient Greek, Greek word κέρας, ''horn''. Structure The cornea has myelinated, unmyelinated nerve endings sensitive to touch, temperature and chemicals; a to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basement Membrane
The basement membrane, also known as base membrane, is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between epithelial tissues including mesothelium and endothelium, and the underlying connective tissue. Structure As seen with the electron microscope, the basement membrane is composed of two layers, the basal lamina and the reticular lamina. The underlying connective tissue attaches to the basal lamina with collagen VII anchoring fibrils and fibrillin microfibrils. The basal lamina layer can further be subdivided into two layers based on their visual appearance in electron microscopy. The lighter-colored layer closer to the epithelium is called the lamina lucida, while the denser-colored layer closer to the connective tissue is called the lamina densa. The electron-dense lamina densa layer is about 30–70 nanometers thick and consists of an und ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corneal Epithelium
The corneal epithelium (epithelium corneae anterior layer) is made up of epithelial tissue and covers the front of the cornea. It acts as a barrier to protect the cornea, resisting the free flow of fluids from the tears, and prevents bacteria from entering the epithelium and corneal stroma. Anatomy The corneal epithelium consists of several layers of cells. The cells of the deepest layer are columnar, known as basal cells which are attached by multiprotein complexes known as hemidesmosomes to an underlying basement membrane. Then follow two or three layers of polyhedral cells, commonly known as wing cells. The majority of these are prickle cells, similar to those found in the stratum mucosum of the cuticle. Lastly, there are three or four layers of squamous cells, with flattened nuclei. The layers of the epithelium are constantly undergoing mitosis. Basal and wing cells migrate to the anterior of the cornea, while squamous cells age and slough off into the tear film. Central t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desquamation
Desquamation, or peeling skin, is the shedding of dead cells from the outermost layer of skin. The term is . Physiologic desquamation Keratinocytes are the predominant cells of the epidermis, the outermost layer of the skin. Living keratinocytes reside in the basal, spinous, or granular layers of the epidermis. The outermost layer of the epidermis is called the stratum corneum and it is composed of terminally differentiated keratinocytes called the corneocytes. In the absence of disease, desquamation occurs when corneocytes are individually shed unnoticeably from the surface of the skin. Typically the time it takes for a corneocyte to be formed and then shed is about 14 weeks but this time can vary depending on the anatomical location that the skin is covering. For example, desquamation occurs more slowly at acral (palm and sole) surfaces and more rapidly where the skin is thin, such as the eyelids. Normal desquamation can be visualized by immersing skin in warm or hot water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LASIK
LASIK or Lasik (; "laser-assisted in situ keratomileusis"), commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and astigmatism. LASIK surgery is performed by an ophthalmologist who uses a femtosecond laser or a microkeratome to create a corneal flap to expose the corneal stroma and then an excimer laser to reshape the corneal stroma in order to improve visual acuity. LASIK is very similar to another surgical corrective procedure, photorefractive keratectomy (PRK), and LASEK. All represent advances over radial keratotomy in the surgical treatment of refractive errors of vision. For people with moderate to high myopia or thin corneas which cannot be treated with LASIK or PRK, the phakic intraocular lens is an alternative. As of 2018, roughly 9.5 million Americans have had LASIK and, globally, between 1991 and 2016, more than 40 million procedures were performed. However, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
