Lens Diseases
Lenses
Contact Lenses, Hydrophilic
Lens Cortex, Crystalline
Lens Capsule, Crystalline
Cataract
Crystallins
Lens Subluxation
Lens epithelial changes and mutated gene expression in patients with myotonic dystrophy. (1/72)
AIMS: Examination of the expression of the mutated allele of myotonic dystrophy protein kinase gene and lens epithelial cell changes in patients with myotonic dystrophy. METHODS: Six eyes from three patients with myotonic dystrophy underwent cataract surgery. The lens epithelium was photographed to examine the morphological changes. mRNAs were extracted to determine myotonic dystrophy protein kinase gene expression in the lens epithelium and peripheral blood. Age matched lens epithelial cells from senile cataracts were used as controls. RESULTS: All eyes showed iridescent or posterior subcapsular lens opacity. The expression of the myotonic dystrophy protein kinase gene with trinucleotide repeat expansion was evaluated by reverse transcriptase polymerase chain reaction, Southern blotting, and sequence analysis. Lens epithelial cell densities were extremely reduced in the patients compared with the control group. CONCLUSION: To the authors' knowledge, this is the first report to describe the relation between lens epithelial cell changes and mutated gene expression in patients with myotonic dystrophy. The gene may be mitotically unstable in the lens epithelial cells; it may influence cell density and lens epithelial function, and it may lead to the development of typical subcapsular lens opacity. (+info)Equine phacoclastic uveitis: the clinical manifestations, light microscopic findings, and therapy of 7 cases. (2/72)
This retrospective clinical study describes the clinical manifestations, light microscopic findings, and diagnosis and treatment of acute and chronic lens rupture in the horse. Rupture of the lens capsule in the horse usually results in a chronic, blinding inflammation (phacoclastic uveitis) unless prompt surgical and medical therapies are implemented. The clinical manifestations of acute lens capsule rupture included: cataract; intralenticular displacement of iridal pigment; lens cortical fragments attached to the perforated lens capsule, iris, and corneal endothelium; miosis; aqueous flare; and usually a corneal or scleral perforation with ulceration or focal full thickness corneal edema and scarring. The clinical signs of chronic phacoclastic uveitis include blindness, phthisis bulbi, and generalized corneal opacification related to scarring, vascularization, pigmentation, and edema. In one horse, acute phacoclastic uveitis was successfully treated with phacoemulsification to remove the ruptured lens and medical therapy to control the accompanying inflammation. The affected eyes of the horses with chronic phacoclastic uveitis were enucleated because of persistent clinical signs of nonulcerative keratitis and uveitis, despite long-term medical management. The clinical manifestations and lack of improvement with medical therapy are similar in the horse, dog, cat, and rabbit. However, the histologic findings in equine phacoclastic uveitis differ significantly from those in the dog, and rabbit. (+info)Herpes simplex virus DNA in the lens one year after an episode of retinitis. (3/72)
The present report describes a case where HSV was detected by polymerase chain reaction (PCR) in the lens cortical material removed during cataract surgery one year after resolution of retinal inflammation in a patient with ARN. (+info)Intraoperative complications during cataract surgery in the very old. (4/72)
PURPOSE: To determine if there is a difference in intraoperative complications during cataract surgery in very old patients (> or = 88 years) compared with younger patients (< 88 years). METHODS: The records of 802 consecutive cataract operations were reviewed. Identical techniques of small-incision phacoemulsification were used in all cases. A total of 102 eyes were in patients aged 88 to 98, designated as the "very old." The remaining 700 eyes were in patients under 88, designated as "younger." The incidence of intraoperative complications in the 2 groups was compared. RESULTS: Posterior capsule tears, vitreous loss, and loss of the nucleus were found as complications. Overall, these events occurred in 10% of the very old and in only 3% of those under age 88. Vitreous loss occurred in 7% of the very old and in only 1.6% of those under 88. There was 1 dropped nucleus in the very old. In the younger patients, 90.5% of eyes with complicated surgery achieved 20/40 visual acuity or better, but only 40% of complicated cases in the very old achieved this. Furthermore, 50% of complicated cases in the very old had visual acuity of 20/200 or worse, all directly attributed to surgical difficulties. Fifteen percent of patients in both groups had trabeculectomies with no influence on complications. We noted that 8% of the very old required pupil stretching compared with 2% of those under 88. CONCLUSIONS: This study strongly suggests that very old patients (i.e., those 88 years and older) have a higher incidence of intraoperative complications during cataract surgery than younger patients. Furthermore, such complications may result in severe visual loss. These findings may have significance as the population ages. (+info)Causes of severe visual impairment and blindness in children attending schools for the visually handicapped in the Czech Republic. (5/72)
AIMS: To describe the causes of severe visual impairment and blindness in children in schools for the visually handicapped in the Czech Republic in 1998. METHODS: Pupils attending all 10 primary schools for the visually handicapped were examined. A modified WHO/PBL eye examination record for children with blindness and low vision was used. RESULTS: 229 children (146 males and 83 females) aged 6-15 years were included in the study: 47 children had severe visual impairment (20.5%) (visual acuity in their better eye less than 6/60), and 159 were blind (69.5%) (visual acuity in their better eye less than 3/60). Anatomically, the most affected parts of the eye were the retina (124, 54.2%), optic nerve (35, 15.3%), whole globe (25, 10.9%), lens (20, 8.7%), and uvea (12, 5.2%). Aetiologically (timing of insult leading to visual loss), the major cause of visual impairment was retinopathy of prematurity (ROP) (96, 41.9 %), followed by abnormalities of unknown timing of insult (97, 42.4%), and hereditary disease (21, 9.2%). In 90 children (40%), additional disabilities were present: mental disability (36, 16%), physical handicap (16, 7%), and/or a combination of both (19, 8%). It was estimated that 127 children (56%) suffer from visual impairment caused by potentially preventable and/or treatable conditions (for example, ROP, cataract, glaucoma). CONCLUSIONS: Establishing a study group for comprehensive evaluation of causes of visual handicap in children in the Czech Republic, as well as for detailed analysis of present practice of screening for ROP was recommended. (+info)Fibrous congenital iris membranes with pupillary distortion. (6/72)
BACKGROUND: In 1986 Cibis and associates described 2 children with a new type of congenital pupillary-iris-lens membrane with goniodysgenesis that was unilateral, sporadic, and progressive. These membranes were different from the common congenital pupillary strands that extend from 1 portion of the iris collarette to another or from the iris collarette to a focal opacity on the anterior lens surface. They also differed from the stationary congenital hypertrophic pupillary membranes that partially occlude the pupil, originating from multiple sites on the iris collarette, but not attaching directly to the lens. CASE MATERIAL: The present report is an account of 7 additional infants with congenital iris membranes, similar to those reported by Cibis and associates, which caused pupillary distortion and were variably associated with adhesions to the lens, goniodysgenesis, and progressive occlusion or seclusion of the pupil. Six of the 7 patients required surgery to open their pupils for visual purposes or to abort angle closure glaucoma. A remarkable finding was that the lenses in the area of the newly created pupils were clear, allowing an unobstructed view of normal fundi. CONCLUSION: This type of fibrous congenital iris membrane is important to recognize because of its impact on vision and its tendency to progress toward pupillary occlusion. Timely surgical intervention can abort this progressive course and allow vision to be preserved. (+info)Exogenous Pseudomonas endophthalmitis: a cause of lens enucleation. (7/72)
Pseudomonas aeruginosa eye infection, although uncommon, may be a devastating disease if not recognised and treated appropriately, especially in premature infants. The case is presented of a premature baby who lost her right eye from invasive exogenous Ps aeruginosa eye infection. (+info)Multiple developmental defects derived from impaired recruitment of ASC-2 to nuclear receptors in mice: implication for posterior lenticonus with cataract. (8/72)
ASC-2, a recently isolated transcriptional coactivator molecule, stimulates transactivation by multiple transcription factors, including nuclear receptors. We generated a potent dominant negative fragment of ASC-2, encompassing the N-terminal LXXLL motif that binds a broad range of nuclear receptors. This fragment, termed DN1, specifically inhibited endogenous ASC-2 from binding these receptors in vivo, whereas DN1/m, in which the LXXLL motif was mutated to LXXAA to abolish the receptor interactions, was inert. Interestingly, DN1 transgenic mice but not DN1/m transgenic mice exhibited severe microphthalmia and posterior lenticonus with cataract as well as a variety of pathophysiological phenotypes in many other organs. Our results provide a novel insight into the molecular and histopathological mechanism of posterior lenticonus with cataract and attest to the importance of ASC-2 as a pivotal transcriptional coactivator of nuclear receptors in vivo. (+info)Lens diseases refer to conditions that affect the lens of the eye, which is a transparent structure located behind the iris and pupil. The main function of the lens is to focus light onto the retina, enabling clear vision. Here are some examples of lens diseases:
1. Cataract: A cataract is a clouding of the lens that affects vision. It is a common age-related condition, but can also be caused by injury, disease, or medication.
2. Presbyopia: This is not strictly a "disease," but rather an age-related change in the lens that causes difficulty focusing on close objects. It typically becomes noticeable in people over the age of 40.
3. Lens dislocation: This occurs when the lens slips out of its normal position, usually due to trauma or a genetic disorder. It can cause vision problems and may require surgical intervention.
4. Lens opacity: This refers to any clouding or opacification of the lens that is not severe enough to be considered a cataract. It can cause visual symptoms such as glare or blurred vision.
5. Anterior subcapsular cataract: This is a type of cataract that forms in the front part of the lens, often as a result of injury or inflammation. It can cause significant visual impairment.
6. Posterior subcapsular cataract: This is another type of cataract that forms at the back of the lens, often as a result of diabetes or certain medications. It can also cause significant visual impairment.
Overall, lens diseases can have a significant impact on vision and quality of life, and may require medical intervention to manage or treat.
In the context of medical terminology, "lenses" generally refers to optical lenses used in various medical devices and instruments. These lenses are typically made of glass or plastic and are designed to refract (bend) light in specific ways to help magnify, focus, or redirect images. Here are some examples:
1. In ophthalmology and optometry, lenses are used in eyeglasses, contact lenses, and ophthalmic instruments to correct vision problems like myopia (nearsightedness), hypermetropia (farsightedness), astigmatism, or presbyopia.
2. In surgical microscopes, lenses are used to provide a magnified and clear view of the operating field during microsurgical procedures like ophthalmic, neurosurgical, or ENT (Ear, Nose, Throat) surgeries.
3. In endoscopes and laparoscopes, lenses are used to transmit light and images from inside the body during minimally invasive surgical procedures.
4. In ophthalmic diagnostic instruments like slit lamps, lenses are used to examine various structures of the eye in detail.
In summary, "lenses" in medical terminology refer to optical components that help manipulate light to aid in diagnosis, treatment, or visual correction.
Contact lenses are thin, curved plastic or silicone hydrogel devices that are placed on the eye to correct vision, replace a missing or damaged cornea, or for cosmetic purposes. They rest on the surface of the eye, called the cornea, and conform to its shape. Contact lenses are designed to float on a thin layer of tears and move with each blink.
There are two main types of contact lenses: soft and rigid gas permeable (RGP). Soft contact lenses are made of flexible hydrophilic (water-absorbing) materials that allow oxygen to pass through the lens to the cornea. RGP lenses are made of harder, more oxygen-permeable materials.
Contact lenses can be used to correct various vision problems, including nearsightedness, farsightedness, astigmatism, and presbyopia. They come in different shapes, sizes, and powers to suit individual needs and preferences. Proper care, handling, and regular check-ups with an eye care professional are essential for maintaining good eye health and preventing complications associated with contact lens wear.
Hydrophilic contact lenses are a type of contact lens that is designed to absorb and retain water. These lenses are made from materials that have an affinity for water, which helps them to remain moist and comfortable on the eye. The water content of hydrophilic contact lenses can vary, but typically ranges from 30-80% by weight.
Hydrophilic contact lenses are often used to correct refractive errors such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. They can be made in a variety of materials, including soft hydrogel and silicone hydrogel.
One advantage of hydrophilic contact lenses is that they tend to be more comfortable to wear than other types of contacts, as they retain moisture and conform closely to the shape of the eye. However, they may also be more prone to deposits and buildup, which can lead to protein accumulation and discomfort over time. Proper care and cleaning are essential to maintain the health of the eyes when wearing hydrophilic contact lenses.
Intraocular lenses (IOLs) are artificial lens implants that are placed inside the eye during ophthalmic surgery, such as cataract removal. These lenses are designed to replace the natural lens of the eye that has become clouded or damaged, thereby restoring vision impairment caused by cataracts or other conditions.
There are several types of intraocular lenses available, including monofocal, multifocal, toric, and accommodative lenses. Monofocal IOLs provide clear vision at a single fixed distance, while multifocal IOLs offer clear vision at multiple distances. Toric IOLs are designed to correct astigmatism, and accommodative IOLs can change shape and position within the eye to allow for a range of vision.
The selection of the appropriate type of intraocular lens depends on various factors, including the patient's individual visual needs, lifestyle, and ocular health. The implantation procedure is typically performed on an outpatient basis and involves minimal discomfort or recovery time. Overall, intraocular lenses have become a safe and effective treatment option for patients with vision impairment due to cataracts or other eye conditions.
The crystalline lens in the eye is composed of three main parts: the capsule, the cortex, and the nucleus. The lens cortex is the outer layer of the lens, located between the capsule and the nucleus. It is made up of proteins and water, and its primary function is to help refract (bend) light rays as they pass through the eye, contributing to the focusing power of the eye.
The cortex is more flexible than the central nucleus, allowing it to change shape and adjust the focus of the eye for different distances. However, with age, the lens cortex can become less elastic, leading to presbyopia, a common age-related condition that affects the ability to focus on close objects. Additionally, changes in the lens cortex have been associated with cataracts, a clouding of the lens that can impair vision.
The crystalline lens of the eye is covered by a transparent, elastic capsule known as the lens capsule. This capsule is made up of collagen and forms the continuous outer layer of the lens. It is highly resistant to both physical and chemical insults, which allows it to protect the lens fibers within. The lens capsule is important for maintaining the shape and transparency of the lens, which are essential for proper focusing of light onto the retina.
The lens nucleus, also known as the crystalline lens nucleus, is the central part of the crystalline lens in the eye. The crystalline lens is a biconvex structure located behind the iris and pupil, which helps to refract (bend) light rays and focus them onto the retina.
The lens nucleus is composed of densely packed lens fibers that have lost their nuclei and cytoplasm during differentiation. It is surrounded by the lens cortex, which consists of younger lens fiber cells that are still metabolically active. The lens nucleus is relatively avascular and receives its nutrients through diffusion from the aqueous humor in the anterior chamber of the eye.
The lens nucleus plays an important role in the accommodation process, which allows the eye to focus on objects at different distances. During accommodation, the ciliary muscles contract and release tension on the lens zonules, allowing the lens to become thicker and increase its curvature. This results in a decrease in the focal length of the lens and enables the eye to focus on nearby objects. The lens nucleus is more rigid than the cortex and helps maintain the shape of the lens during accommodation.
Changes in the lens nucleus are associated with several age-related eye conditions, including cataracts and presbyopia. Cataracts occur when the lens becomes cloudy or opaque, leading to a decrease in vision clarity. Presbyopia is a condition that affects the ability to focus on near objects and is caused by a hardening of the lens nucleus and a loss of elasticity in the lens fibers.
A cataract is a clouding of the natural lens in the eye that affects vision. This clouding can cause vision to become blurry, faded, or dim, making it difficult to see clearly. Cataracts are a common age-related condition, but they can also be caused by injury, disease, or medication use. In most cases, cataracts develop gradually over time and can be treated with surgery to remove the cloudy lens and replace it with an artificial one.
Crystallins are the major proteins found in the lens of the eye in vertebrates. They make up about 90% of the protein content in the lens and are responsible for maintaining the transparency and refractive properties of the lens, which are essential for clear vision. There are two main types of crystallins, alpha (α) and beta/gamma (β/γ), which are further divided into several subtypes. These proteins are highly stable and have a long half-life, which allows them to remain in the lens for an extended period of time. Mutations in crystallin genes have been associated with various eye disorders, including cataracts and certain types of glaucoma.
Extended-wear contact lenses are a type of contact lens that is designed to be worn continuously, including during sleep, for an extended period of time. These lenses are typically made from materials that allow more oxygen to reach the eye, reducing the risk of eye irritation and infection compared to traditional overnight wear of non-extended wear lenses.
Extended-wear contact lenses can be worn for up to 30 days or longer, depending on the specific lens material and the individual's tolerance. However, it is important to note that even extended-wear contacts come with some risks, including a higher risk of eye infections and corneal ulcers compared to daily wear lenses. Therefore, it is essential to follow the recommended wearing schedule and replacement schedule provided by an eye care professional, as well as to have regular eye exams to monitor the health of the eyes.
Lens subluxation, also known as lens dislocation or ectopia lentis, is a condition where the lens of the eye becomes partially or completely displaced from its normal position. The lens is held in place by tiny fibers called zonules, which can become weakened or broken due to various reasons such as genetic disorders (like Marfan syndrome, homocystinuria, and Weill-Marchesani syndrome), trauma, inflammation, or cataract surgery complications. This displacement can lead to symptoms like blurry vision, double vision, sensitivity to light, or the appearance of a shadow in the peripheral vision. In some cases, lens subluxation may not cause any noticeable symptoms and can be discovered during routine eye examinations. Treatment options depend on the severity and underlying cause of the subluxation and may include eyeglasses, contact lenses, or surgical intervention to remove and replace the displaced lens with an intraocular lens (IOL).
Contact lens solutions are a type of disinfecting and cleaning solution specifically designed for use with contact lenses. They typically contain a combination of chemicals, such as preservatives, disinfectants, and surfactants, that work together to clean, disinfect, and store contact lenses safely and effectively.
There are several types of contact lens solutions available, including:
1. Multipurpose solution: This type of solution is the most commonly used and can be used for cleaning, rinsing, disinfecting, and storing soft contact lenses. It contains a combination of ingredients that perform all these functions in one step.
2. Hydrogen peroxide solution: This type of solution contains hydrogen peroxide as the main active ingredient, which is a powerful disinfectant. However, it requires a special case called a neutralizer to convert the hydrogen peroxide into water and oxygen before using the lenses.
3. Saline solution: This type of solution is used only for rinsing and storing contact lenses and does not contain any disinfecting or cleaning agents. It is often used in combination with other solutions for a complete contact lens care routine.
4. Daily cleaner: This type of solution is used to remove protein buildup and other deposits from the surface of contact lenses. It should be used in conjunction with a multipurpose or hydrogen peroxide solution as part of a daily cleaning routine.
It's important to follow the manufacturer's instructions carefully when using contact lens solutions to ensure that they are used safely and effectively. Failure to do so could result in eye irritation, infection, or other complications.