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Cataracts

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Defined as a clouding of the normally clear crystalline lens of the eye.

More than 15 million adults older than 65 years have cataracts.

Most common cause of blindness in blacks.

The lens in the eyeball sits behind the iris, and normally is perfectly clear, but as one ages, pigment and other things are deposited within the lens making it cloudy.

If the lens is cloudy the image gets blurred, and blurring of the image by the lens is a cataract.

Lens opacities make vision more difficult, especially under dim light and under conditions of glare, such as when driving at night.

Typically appears black on direct ophthalomoscopy and white when light is shone

latterly at the eye and the observer looks directly at the eye.

The pulpy part of the cataract, the cortex, is soft and that can be easily removed with proper instrumentation.

Can vary in size from pinpoint to completely obscuring the retinal reflex.

May be unilateral or bilateral.

Congenital cataracts occur in approximately two per10,000 live births.

Prevalence of congenital cataracts varies among countries and depends on factors such as access obstetrical care and the incidence of congenital rubella.

Infectious causes of congenital cataracts include toxoplasmosis, cytomegalic virus, rubella, syphilis, herpes simplex virus, measles, polio, influenza, and varicella-zoster virus.

Most common metabolic causes of cataracts are galactosemia.

Cataracs due to galactosemia can develop within a few days of life but are not visible at birth.

Associated with inflammation, free-radical oxidative injury and accumulation of glucation products.

Associated with cardiovascular morbidity and mortality.

Associated with an increased risk of atrial fibrillation (Hu, Wei-Syun)

Surgery for visually significant congenital cataracts should occur between four and eight weeks of life.

Nonvisual significant cataracts can convert to visually significant lesions overtime and need to be monitored.

The nucleus is hard and has to be broken up by phacoemulsification and then can be removed.

Femtosecond laser cuts the capsule in a circular fashion to achieve a perfectly circular 4.5 mm to 5.5 mm tear in the capsule.

The femtosecond laser photodisrupts the interior of the cataract, the cortex and part of the nucleus, making it softer and easier to remove.

The incision occurs in the clear cornea, and the lens implant can be folded, put in the eye, and then it opens itself.

The femtolaser can also make small incisions in the cornea to correct astigmatism and refractive 2242ors, at the time the cataract is removed.

The leading cause of blindness worldwide.

Cause cloudy, blurry vision, glare, halos, decreased night vision and need for brighter light when reading.

Caused by oxidative stress and osmotic imbalances resulting from stresses of physiologic and environmental factors, combined with reduction in the eyes ability to defend against, or repair damage.

Associated with ultraviolet light exposure, smoking, diabetes, and excessive alcohol, all conditions associated with greater oxidative stress.

Dietary total anti-oxidant capacity is inversely associated with the risk of age-related cataract.

Cataract surgery is the most frequent performed surgical procedure in the U.S. with more than 1.5 million operations each year.

Increased risk with cigarette smoking, exposure to UV-B light, high alcohol intake, diabetes, steroids, ocular surgery, and trauma.

Smoking cessation is the main strategy to prevent cataract.

There is an inverse relationship between vitamin C intake and incidence of cataracts.

High dietary intakes of vitamin C and higher plasma ascorbate concentrations have been associated with a lower risk of cataract formation.

 

Vitamin C intakes greater than 300 mg/day reduce the risk of cataract formation by 70%–75%.

Patients with the highest level of legume intake are 67% less likely to develop cataracts than those in the lowest level of legume intake.

Types of cataracts include nuclear, cortical, posterior subcapsular and mixed.

Nuclear cataracts are the most common type of age-related cataract leading to surgery.

Nuclear cataracts have central lens opacities and have a genetic component with age, female sex, and smoking significant risk factors.

Cortical cataracts linked to sunlight exposure.

Oxidative stress postulated to be a risk factor for age-related cataracts, especially for nuclear cataract.

Inverse relationship between the use of statins and incidence of nuclear cataracts.

More than half of the population older than 65 years develops age-related cataracts. Cataracts-10% related to UV.

Highly prevalent condition among older persons, with almost half exhibiting early cataract by age 75 years and approximately one quarter with more advanced cataract.

White individuals more likely to have nuclear and posterior subcapsular opacities.

4 fold prevalence of cortical cataracts among black individuals.

Corticosteroids associated with posterior subcapsular opacities.

Diabetes associated with posterior subcapsular opacities.

Associated with an 30-50% increased mortality risk.

Obesity associated with posterior subcapsular opacities.

Osteoporosis is associated with the presence of cataracts, with pathophysiological associations with both conditions, such as calcium imbalance, hormonal abnormalities, and shared genetic predisposition.

The visual effects of cataracts are additive to the physiological consequences of other diseases or conditions.

Cataract traditionally have deficits of blur, distortion, glare, and reduced contrast sensitivity.

The central scotoma due to macular degeneration added to cataract deficits greatly impairs vision.

The scotoma from the macular degeneration requires the patient to use para- or peri-macular retinal elements which require higher contrast, brighter light, and usually larger images to compensate for the missing foveal sensitivity.

Macular degeneration in the presence of a cataract the brighter the light, the more glare there is, which also reduces contrast, and renders magnification less effective than would be predicted from the patient�s visual acuity.

A cataract and macular disease together could be visually more devastating than their additive effect.

The pathophysiology of the most common cataracts is age-related, and it is closely associated with other diseases and conditions which are also age-related.

The most common age-related conditions, besides cataract, are: macular degeneration, glaucoma, and diabetic retinopathy.

In the younger patient population the condition that is often associated with cataract and requires surgery is retinitis pigmentosa.

The Humphrey visual field test assesses the potential for visual improvement from cataract surgery.

Patients with macular degeneration and cataracts sometimes benefit from cataract extraction, despite the presence of macular disease.

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