Cataract
Classification and external resources
Magnified view of cataract in human eye, seen on examination with a slit lamp using diffuse illumination
ICD-10	H25-H26, H28, Q12.0
ICD-9	366
DiseasesDB	2179
MedlinePlus	001001
eMedicine	article/1210914

A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope (lens capsule), varying in degree from slight to complete opacity and obstructing the passage of light. Early in the development of age-related cataract, the power of the lens may be increased, causing near-sightedness (myopia), and the gradual yellowing and opacification of the lens may reduce the perception of blue colors. Cataracts typically progress slowly to cause vision loss, and are potentially blinding if untreated. The condition usually affects both eyes, but almost always one eye is affected earlier than the other.^[1]

A senile cataract, occurring in the elderly, is characterized by an initial opacity in the lens, subsequent swelling of the lens and final shrinkage with complete loss of transparency.^[2] Moreover, with time the cataract cortex liquefies to form a milky white fluid in a Morgagnian cataract, which can cause severe inflammation if the lens capsule ruptures and leaks. Untreated, the cataract can cause phacomorphic glaucoma. Very advanced cataracts with weak zonules are liable to dislocation anteriorly or posteriorly. Such spontaneous posterior dislocations (akin to the historical surgical procedure of couching) in ancient times were regarded as a blessing from the heavens, because some perception of light was restored in the cataractous patients.

Some children develop cataracts, called congenital cataracts, before or just after birth; these are usually dealt with differently from cataracts in adults.^[3]

Cataract derives from the Latin cataracta meaning "waterfall" and that from the Greek καταράκτης (kataraktēs) or καταρράκτης (katarrhaktēs), "down-rushing",^[4] from καταράσσω (katarassō) meaning "to dash down"^[5] (from kata-, "down"; arassein, "to strike, dash").^[6][7] As rapidly running water turns white, the term may later have been used metaphorically to describe the similar appearance of mature ocular opacities. In Latin, cataracta had the alternate meaning "portcullis"^[8] and the name possibly passed through French to form the English meaning "eye disease" (early 15th century), on the notion of "obstruction".^[9] Early Persian physicians called the term nazul-i-ah, or "descent of the water"—vulgarised into waterfall disease or cataract—believing such blindness to be caused by an outpouring of corrupt humour into the eye.^[10]

Signs and symptoms[link]

As a cataract becomes more opaque, clear vision is compromised. A loss of visual acuity is noted. Contrast sensitivity is also lost, so contours, shadows and color vision are less vivid. Veiling glare can be a problem, as light is scattered by the cataract into the eye. The affected eye will have an absent red reflex. A contrast sensitivity test should be performed, and if a loss is demonstrated, an eye specialist consultation is recommended.

It may be advisable to seek medical opinion, particularly in high-risk groups such as diabetics, if a "halo" is observed around street lights at night, especially if this phenomenon appears to be confined to one eye only.

The symptoms of cataracts are very similar to the symptoms of ocular citrosis.

Causes[link]

Human eye cross-sectional view, showing the position of the human lens, courtesy NIH National Eye Institute

Several factors can promote the formation of cataracts, including long-term exposure to ultraviolet light, exposure to ionizing radiation, secondary effects of diseases such as diabetes, hypertension and advanced age, or trauma (possibly much earlier); they are usually a result of denaturation of lens protein. Genetic factors are often a cause of congenital cataracts, and positive family history may also play a role in predisposing someone to cataracts at an earlier age, a phenomenon of "anticipation" in presenile cataracts. Cataracts may also be produced by eye injury or physical trauma. A study among Icelandair pilots showed commercial airline pilots are three times more likely to develop cataracts than people with nonflying jobs. This is thought to be caused by excessive exposure at high altitudes to radiation coming from outer space, which becomes attenuated by atmospheric absorption at ground level.^[11] Supporting this theory is the report that 33 of the 36 Apollo astronauts involved in the nine Apollo missions to leave Earth orbit have developed early stage cataracts that have been shown to be caused by exposure to cosmic rays during their trips.^[12] At least 39 former astronauts have developed cataracts, of whom 36 were involved in high-radiation missions such as the Apollo missions.^[13] Cataracts are also unusually common in persons exposed to infrared radiation, such as glassblowers, who suffer from exfoliation syndrome. Exposure to microwave radiation can cause cataracts^{[citation needed]}. Atopic or allergic conditions are also known to quicken the progression of cataracts, especially in children.^[14] Cataracts can also be caused by iodine deficiency.^[15]

Cataracts may be partial or complete, stationary or progressive, or hard or soft.

Some drugs can induce cataract development, such as corticosteroids^[16] and the antipsychotic drug quetiapine (sold as Seroquel, Ketipinor, or Quepin).

The various types of cataracts are nuclear, cortical, mature, and hypermature. Cataracts are also classified by their location, e.g. posterior (classically due to steroid use)^[16][17] and anterior (common (senile) cataract related to aging).

Associations with systemic conditions[link]

• Chromosomal disorders

• 1q21.1 deletion syndrome
• Cri-du-chat syndrome
• Patau's syndrome
• Schmid-Fraccaro syndrome
• Trisomy 18 (Edward's syndrome)
• Turner's syndrome

• Single-gene disorders

• Alport's syndrome
• Conradi's syndrome
• Myotonic dystrophy
• Autosomal dominant severe keratoconus with anterior polar cataract caused by mutation of the miR-184 seed region^[18]

• Disease of the skin and mucous membranes

• Atopic dermatitis
• Basal-cell nevus syndrome
• Ichthyosis
• Pemphigus

• Metabolic and nutrition diseases

• Aminoaciduria or Lowe's syndrome)
• Diabetes mellitus
• Fabry's disease
• Galactosemia / galactosemic cataract
• Homocystinuria
• Hyperparathyroidism
• Hypervitaminosis D
• Hypothyroidism
• Mucopolysaccharidoses
• Wilson's disease

• Infectious diseases

• Congenital

• Congenital herpes simplex
• Congenital syphilis
• Cytomegalic inclusion disease
• Rubella

• Others

• Cysticercosis
• Leprosy
• Onchocerciasis
• Toxoplasmosis

• Toxic substances introduced systemically

• Corticosteroids
• Haloperidol
• Miotics
• Triparanol

Classification[link]

Bilateral cataracts in an infant due to congenital rubella syndrome

The following is a classification of the various types of cataracts. This is not comprehensive, and other unusual types may be noted.

• Classified by etiology

• Age-related cataract

• Cortical senile cataract

• Immature senile cataract (IMSC): partially opaque lens, disc view^{[clarification needed]} hazy
• Mature senile cataract (MSC): completely opaque lens, no disc view
• Hypermature senile cataract (HMSC): liquefied cortical matter: Morgagnian cataract

• Senile nuclear cataract

• Cataracta brunescens
• Cataracta nigra
• Cataracta rubra

• Congenital cataract

• Sutural cataract
• Lamellar cataract
• Zonular cataract
• Total cataract

• Secondary cataract

Slit lamp photo of anterior capsular opacification visible a few months after implantation of intraocular lens in eye, magnified view

• Drug-induced cataract (e.g. corticosteroids)

• Traumatic cataract

• Blunt trauma (capsule usually intact)
• Penetrating trauma (capsular rupture and leakage of lens material—calls for an emergency surgery for extraction of lens and leaked material to minimize further damage)

• Classified by opacities, cataract can be classified by using Lens Opacities Classification System III (LOCS III: Nuclear NC1-5, Cortical C1-5 and Posterior P1-5. By application planning in procedures of phacoemulsification, LCOS III can be converted in newer cataract grading systems. Gede Pardianto (2009) introduced Optical Biometry Based Cataract Grading System (OBBCGS) that is helpful in cataract grading due to phacoemulsification planning. LOCS III's NC0, C0 and P0 can be converted as OBBCGS' no cataract (NC), LOCS III's NC1-3, C1-3, P1-4 can be converted to OBBCGS' Optical Biometry Examined Cataract (OBEC) and LOCS III's NC4-5, C4-5, P4-5 can be converted to OBBCGS's Optical Biometry Unexamined Cataract (OBUC); that need examination by Applanation Ultrasound Biometry.^[19]

• Classified by location of opacity within lens structure (however, mixed morphology is quite commonly seen, e.g. PSC with nuclear changes and cortical spokes of cataract)

• Anterior cortical cataract
• Anterior polar cataract
• Anterior subcapsular cataract

Slit lamp photo of posterior capsular opacification visible a few months after implantation of intraocular lens in eye, seen on retroillumination

• Nuclear cataract (affecting the lens nucleus) — grading correlates with hardness and difficulty of surgical removal

• 1: Grey
• 2: Yellow
• 3: Amber
• 4: Brown/black (Note: "black cataract" translated in some languages (like Hindi) refers to glaucoma, not the color of the lens nucleus)

• Posterior cortical cataract
• Posterior polar cataract (importance lies in higher risk of complication—posterior capsular tears during surgery)
• Posterior subcapsular cataract (PSC) (clinically common)
• After-cataract: posterior capsular opacification (PCO) subsequent to a successful extracapsular cataract surgery (usually within three months to two years) with or without IOL implantation. Requires a quick and painless office procedure with Nd:YAG laser capsulotomy to restore optical clarity.

Prevention[link]

Although cataracts have no scientifically proven prevention, wearing ultraviolet-protecting sunglasses may slow the development of cataracts.^[20][21] It has been suggested that regular intake of antioxidants (such as vitamins A, C and E) is helpful, but taking them as a supplement has not been shown to have a benefit.^[22]

Although statins are known for their ability to lower lipids, they are also believed to have antioxidant qualities. Oxidative stress is believed to play a role in the development of nuclear cataracts, which are the most common type of age-related cataracts. To explore the relationship between nuclear cataracts and statin use, a group of researchers treated a group of 1299 patients who were at risk of developing nuclear cataracts with statins. Their results suggest statin use in an at-risk population may be associated with a lower risk of developing nuclear cataract disease.^{[23][better source needed]}

Treatment[link]

In 1960 Svyatoslav Fyodorov performed the first intraocular lens replacement operation, inventing the cure to the cataract; all the modern treatments start from here.

Non-surgical[link]

Topical treatment (eye drops) with the less well-known antioxidant N-acetylcarnosine has been shown in randomized controlled clinical trials to improve transmissivity and reduce glare sensitivity for patients with cataracts.^[24] After animal experiments researchers of a pharmaceutical company have proposed N-acetylcarnosine as a treatment for ocular disorders that have a component of oxidative stress in their genesis, including cataracts, glaucoma, retinal degeneration, corneal disorders, and ocular inflammation.^[25]

Long term (average five year) observation showed systematic application of azapentacene sodium polysulfonate (Quinax) slows down the progress of the disease.^[26]

Surgical[link]

Cataract surgery, using a temporal approach phacoemulsification probe (in right hand) and "chopper" (in left hand) being done under operating microscope at a Navy medical center

The operation to remove cataracts can be performed at any stage of their development. There is no longer a reason to wait until a cataract is "ripe" before removing it.^[27] However, because all surgery involves some risk, it is usually worth waiting until there is some change in vision before removing the cataract.^[27]

The most effective and common treatment is to make an incision (capsulotomy) into the capsule of the cloudy lens to surgically remove it. Two types of eye surgery can be used to remove cataracts: extracapsular cataract extraction (ECCE) and intracapsular cataract extraction (ICCE).

ECCE surgery consists of removing the lens, but leaving the majority of the lens capsule intact. High frequency sound waves (phacoemulsification) are sometimes used to break up the lens before extraction.

Intra-capsular (ICCE) surgery involves removing the lens and lens capsule, but it is rarely performed in modern practice.

In either extracapsular surgery or intracapsular surgery, the cataractous lens is removed and replaced with a plastic lens (an intraocular lens implant) which stays in the eye permanently.

Cataract operations are usually performed using a local anaesthetic, and the patient is allowed to go home the same day. Until the early twentyfirst century intraocular lenses were always monofocal; since then improvements in intraocular technology allow implanting a multifocal lens to create a visual environment in which patients are less dependent on glasses. Such multifocal lenses are mechanically flexible and can be controlled using the eye muscles used to control the natural lens.

Complications are possible after cataract surgery, including endophthalmitis, posterior capsular opacification and retinal detachment.

Laser surgery involves cutting away a small circle-shaped area of the lens capsule, enough to allow light to pass directly through the eye to the retina. There are, as always, some risks, but serious side effects are very rare.^[28] As of 2012^[update] research into the use of extremely-short-pulse (femtosecond) lasers for cataract surgery was being carried out^[29].

High frequency ultrasound is also used for cataract surgery^[30].

Epidemiology[link]

Disability-adjusted life year for cataracts per 100,000 inhabitants in 2004.^[31]

no data   <90   90-180   180-270   270-360   360-450   450-540

540-630   630-720   720-810   810-900   900-990   >990

Age-related cataract is responsible for 48% of world blindness, which represents about 18 million people, according to the World Health Organization (WHO).^[32] In many countries, surgical services are inadequate, and cataracts remain the leading cause of blindness. As populations age, the number of people with cataracts is growing. Cataracts are also an important cause of low vision in both developed and developing countries. Even where surgical services are available, low vision associated with cataracts may still be prevalent, as a result of long waits for operations and barriers to surgical uptake, such as cost, lack of information and transportation problems.

In the United States, age-related lenticular changes have been reported in 42% of those between the ages of 52 and 64,^[33] 60% of those between the ages 65 and 74,^[34] and 91% of those between the ages of 75 and 85.^[33]

The increase in ultraviolet radiation resulting from depletion of the ozone layer is expected to increase the incidence of cataracts.^[35]

History[link]

The first references to cataract and its treatment in Ancient Rome are found in 29 CE in De Medicinae, the work of the Latin encyclopedist Aulus Cornelius Celsus.^[36] The Romans were pioneers in the health arena—particularly in the area of eye care.^[37]

Other early accounts are those in Sanskrit medical literature. Early cataract surgery was described by the Indian physician, Suśruta (fl. ca. AD 200).^[38] For a full citation translated from the original Sanskrit, see the Wikipedia entry on Cataract Surgery.

The Muslim ophthalmologist Ammar ibn Ali, in his Choice of Eye Diseases, written circa 1000 CE, wrote of his invention of the hypodermic needle and how he discovered the technique of cataract extraction while experimenting with it on a patient.^[39]

Research[link]

Research is scant and mixed, but weakly positive, for the nutrients lutein and zeaxanthin.^{[40][41][42][43]} Bilberry extract shows promise in rat models^[44][45] and in clinical studies.^[46]

In the early 2000s eye drops containing acetyl-carnosine have been used by several thousands of cataract patients across the world. The drops are believed to work by reducing oxidation and glycation damage in the lens, particularly reducing crystallin crosslinking.^[47][48] Randomized controlled trials indicate the drops may be especially appropriate for seniors, or others where surgery is not advised.^[49]

References and notes[link]

External links[link]

• Cataract at the Open Directory Project

Casey Dienel
Background information
Origin	Scituate, Massachusetts
Genres	Pop Indie pop Dream Pop
Occupations	Singer-songwriter, pianist, composer
Years active	1999–present
Labels	Dead Oceans, Hush Records
Associated acts	White Hinterland
Website	White Hinterland

Casey Dienel (born March 10, 1985) is an American singer-songwriter and pianist. She released her debut album, Wind-Up Canary, in 2006 on Hush Records. Dienel presently performs and records as White Hinterland, whose first album, titled Phylactery Factory, was released on March 4, 2008, by the independent record label Dead Oceans.

Biography[link]

Casey Dienel spent the bulk of her young life living in Scituate, Massachusetts. She took her first piano lessons at age 4, and at age 14 began writing her own pop songs.^[1] While attending Scituate High School, Dienel formed a short-lived band named The Bong Loads.

After high school, Dienel moved to Boston to attend the New England Conservatory of Music, having turned down an offer of acceptance from Sarah Lawrence College. After one semester of studying classical vocals, she opted to switch her major to classical composition. During her two years at the conservatory, Dienel studied with many notable musicians, including jazz vocalist Dominique Eade and composer Lee Hyla, before taking an indefinite leave of absence to pursue her own music career.

While living in Boston during her Conservatory years, Dienel met Dylan Metrano of the band Tiger Saw, and was an occasional member of the band's rotating lineup. She currently lives in Portland, OR.^[2]

Wind-Up Canary[link]

During the winter of 2005, Dienel was offered the chance to record for free at an abandoned caretaker's house on a farm in Leominster, Massachusetts. With some Conservatory friends and a piano borrowed from the lobby of a local hotel, she recorded a number of her own songs without any intention of releasing them. Without Dienel's knowledge, a copy of these recordings made its way to Chad Crouch, the head of Hush Records, who contacted her about releasing an album.^[3] Dienel agreed and Hush released the recordings as Wind-Up Canary in March 2006.

Vessels[link]

On November 29, 2006, Casey Dienel announced that she was working with producer Djim Reynolds on recording an EP titled Vessels, and that she hoped to release it in early 2007. Dienel had this to say about the project:

I've had my head shoved in the books for several weeks now, attempting to finish a little EP for your ears that I'm calling Vessels. I can't talk too much about it, for you know how fickle I am when it comes to these things, but hopefully in the new year it will find its way to your hands with ribbons and brass, etc. I can tell you that some sounds are sprawling and some are still quite intimate, and it features a few of my favorite friends with me.^[4]

To date, Vessels remains unreleased—however, there are live recordings and lyrics for the song online.

White Hinterland[link]

On January 4, 2008, after a few months hinting at "change,"^[5] Dienel announced in her blog that "for the present and foreseeable future, there won’t be any more Casey Dienel."^[6] Her blog post coincided with Dead Oceans' announcement of the forthcoming release of White Hinterland's album Phylactery Factory:

2008 is here, and with the new year comes the influx of new albums. Dead Oceans is thrilled to partake in this ritual, and we are enthused to officially welcome White Hinterland to our label family. Led by the talented Casey Dienel, White Hinterland have crafted the mysterious Phylactery Factory, which will arrive in record stores worldwide on March 4, 2008.^[7]

In 2010, White Hinterland (consisting of the duo Dienel and artist/musician/collaborator Shawn Creeden) toured the US and Europe with their album Kairos. A song from this album, "Icarus", was selected by Revlon to be used in their 2010 commercial for Just Bitten Lip Stain, starring Jessica Biel and directed by Kathryn Bigelow. Later the same year, "Icarus" was featured in an episode of the ABC Family drama "Pretty Little Liars," as well the fashion show of the winner of the Project Runway (Season 8) finale , Gretchen Jones. The song was also used in the 2010 film It's Kind of a Funny Story.

Discography[link]

As Casey Dienel:

• 2006 Wind-Up Canary (Hush Records)

As White Hinterland:

• 2008 Phylactery Factory (Dead Oceans)
• 2008 "Luniculaire" EP (Dead Oceans)
• 2010 "Kairos" (Dead Oceans)

References[link]

1. ↑ Casey Dienel: Shining A Floodlight On The Humanness Of Strippers And At Least One Ladies Man
2. ↑ http://wweek.com/editorial/3529/12604/
3. ↑ Hush Records: Casey Dienel - "Wind-Up Canary"
4. ↑ "Musings - my book report.". Casey Dienel. 2006. http://nonsequitortoise.blogspot.com/2006/11/my-book-report_29.html. Retrieved December 22, 2006. 
5. ↑ Musings: Bleating Hearts
6. ↑ Musings: Ends in the Beginnings.
7. ↑ DeadOceans.com, 01/05/08

External links[link]

• WhiteHinterland.com: official website
• Myspace.com: Casey Dienel's artist page
• Musings: Casey Dienel's blog