Brief Summary of Cataract

 Opthalmology  Comments Off
Mar 202012
 
A common cause of vision loss, a cataract is a gradually developing opacity of the lens or lens capsule of the eye. Cataracts commonly occur bilaterally, with each progressing independently. Exceptions are traumatic cataracts, which are usually unilateral, and congenital cataracts, which may remain stationary.
Cataracts are a part of aging and are most prevalent in patients older than age 70. Surgical intervention improves vision in 95% of affected people.
Causes
Cataracts have various causes, depending on their type:
  • Senile cataracts develop in elderly patients, probably because of degenerative changes in the chemical state of lens proteins.
  • Congenital cataracts occur in neonates as genetic defects or as a result of maternal rubella during the 1st trimester.
  • Traumatic cataracts develop after a foreign body injures the lens with sufficient force to allow aqueous or vitreous humors to enter the lens capsule.
  • Complicated cataracts develop as secondary effects in patients with uveitis, glaucoma, retinitis pigmentosa, or a detached retina or in the course of a systemic disease, such as diabetes, hypoparathyroidism, or atopic dermatitis. These cataracts can also result from exposure to ionizing radiation or infrared rays.
  • Toxic cataracts result from prolonged drug or chemical toxicity from prednisone, ergot Continue reading »
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Corneal abrasion

 Opthalmology  Comments Off
Feb 272012
 
Commonly caused by a foreign body, a corneal abrasion is a scratch on the surface epithelium of the cornea. An abrasion or foreign body in the eye is the most common eye injury. With treatment, the prognosis is usually good.
Causes
A corneal abrasion usually results from a foreign body, such as a cinder or a piece of dust, dirt, or grit, which becomes embedded under the eyelid. Even if the foreign body is washed out by tears, it may still injure the cornea.
A small piece of metal that gets in the eyes of workers who don’t wear protective glasses quickly forms an abrasion and then forms a rust ring on the cornea. Abrasions also commonly occur in the eyes of people who fall asleep wearing hard contact lenses. A corneal scratch produced by a fingernail, a piece of paper, or another organic substance may cause a persistent lesion. The epithelium doesn’t always heal properly, and a recurrent corneal erosion may develop, with delayed effects more severe than those of the original injury.
Signs and symptoms
Typically, corneal abrasions produce redness, increased tearing, a sensation of “something in the eye” and, because the cornea is richly endowed with nerve endings from the trigeminal nerve (cranial nerve V), pain disproportionate to the size of the injury. A corneal abrasion may affect Continue reading »
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Macular degeneration

 Opthalmology  Comments Off
Aug 252011
 
Macular degeneration, which is atrophy or degeneration of the macular disk, accounts for about 12% of all cases of blindness in the United States and for about 17% of new cases of blindness. It’s one of the causes of severe irreversible loss of central vision in people older than age 50. It affects slightly more women than men.
Types of Macular Degenaration
Two types of age-related macular degeneration occur. The dry, or atrophic, form is characterized by atrophic pigment epithelial changes and is usually associated with a slow, progressive distortion of straight lines or edges and central visual loss. The wet, or exudative, form causes rapid onset of visual impairment. It’s characterized by subretinal neovascularization that causes leakage, hemorrhage, and fibrovascular scar formation, which produce significant loss of central vision.
Causes
Age-related macular degeneration results from the formation of drusen (clumps of epithelium) or subretinal neovascular membrane in the macular region. It may be hereditary. Cigarette smoking and lack of antioxidants, such as vitamins C and E, may also enhance occurrence.
Underlying pathologic changes occur primarily at the level of the retinal pigment epithelium, Bruch’s membrane, and choriocapillaris in the macular region. Drusen (bumps), which are common in elderly people, appear as yellow deposits beneath the pigment epithelium and may be prominent in the macula.
Signs and symptoms
The patient notices a change in central vision; for example, he may notice a blank spot in the center of the page when reading.
Diagnosis
The following tests are used to diagnose macular degeneration:
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