The Eye

Nam Deuk Kim

Pusan National University

1

Contents

1. The orbit: exophthalmos of hyperthyroidism

2. The cornea

3. The lens: cataracts

4. The uvea

5. The retina

6. The optic nerve

7. Glaucoma

8. Ocular neoplasms

2

Formation and Drainage of

Aqueous Humor

Aqueous humor is formed by capillary

network in ciliary body, then drains into the

canal of Schlemm, and eventually enters

the blood.

The normal retina. Constituents of the normal retina are arranged in distinct layers. These include the nerve fiber layer (NFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), inner segments (IS) and outer segments (OS) of the photoreceptors and the retinal pigment epithelium (RPE). The axons from the ganglion cells enter the nerve fiber layer and converge toward the optic nerve head. The inner retina contains arteries and veins. The retina is thinnest at the center of the macula, where bare photoreceptors rest on the retinal pigment epithelium. Only one cell thick in most of the retina, the ganglion cell layer is multilayered at the macula.

1.The orbit: exophthalmos (안구돌

출증) of hyperthyroidism

A. Exophthalmos (안구돌출)

• Diffuse hyperthyroidism (Graves’

disease): bilateral exophthalmos

• Occurs in early adult life,

especially in women (female-to-

male = 4:1)

• May severe & progressive,

particularly in during middle age

• Caused by enlargement of the

orbital extraocular muscles that

are swollen by mucinous edema,

accumulation of fibroblasts, &

lymphocyte infiltration

B. Proptosis (돌출): unilateral

protrusion (한쪽만 돌출) of the

eye by increased orbital contents

안구돌출증:

• 눈 조직의 glycosaminoglycans에 의해 유발되는 삼투압의 증가, 수분 증가, 안 조직의 부피 증가 결과로 유발

• 임파구와 다른 단핵구세포들로 침윤되어 팽대된 안외근육도 기여함

• 안구돌출증의 경과: 각막 노출, 궤양, 이차 녹내장, 시신경 압박 등과 같은 잠재적 실명

2. The cornea (각막)

1) Herpes simplex virus (HSV) causes corneal ulcerations

• an inflammatory or more seriously, infective condition of the cornea (각막) involving disruption of its epithelial layer with involvement of the corneal stroma.

• Many micro-organisms cause infective corneal ulcer. Among them are bacteria, fungi, viruses, protozoa, and chlamydia.

A. Primary infection by HSV type 1: Herpes virus cause a dendritic ulcer, which can recur and relapse over the lifetime of an individual.

B. Reactivation of HSV infection

• Pathology:

- Dendritic ulcers (수지상 궤양)

- Disciform keratitis (원반각막염)

- Descemetocele (데스메막류)

8

2) Corneal dystrophies (각막영양장애) encompass diverse noninflammatory genetic corneal disorders

• Coreneal dystrophies: a heterogeneous group of hereditary, noninflammatory, and degenerative diseases of the cornea

A. Epithelial dystrophies (상피성 영양장애):

• a rare form of human corneal dystrophy first described in 1992 by Lisch et al.

• In one study it was linked to chromosomal region Xp22.3, with as yet unknown candidate genes.

• Bilateral or unilateral gray band-shaped and feathery opacities.

• They sometimes take on a form of a whirlpool, repeating the known pattern of corneal epithelium renewal.

• Abrasion of the epithelium in 3 patients brought only temporary relief, with abnormal epithelium regrowth in several months.

• Epithelial cells in the zones of opacity were shown to have diffuse cytoplasmic vacuoles with as yet unestablished content.

B. Stromal dystrophies(기질성 영양장애):

• Clear-cut entities in which different substances (e.g., amyloid, glycosaminoglyhcans, proteins, or a variety of lipids) accumulate within corneal stroma because of inherited metabolic disorders.

• Age of onset and rate of progression: vary with the particular disorder

• Result from different mutations in the TFGBI (BGH3) gene on chromosome 5 (5q31).

9

C. Endothelial dystrophies (혈관 내피성 영양장애): • also known as Fuchs' endothelial

dystrophy, is a slowly progressing corneal disease that usually affects both eyes and is slightly more common in women than in men.

• Although doctors can often see early signs of Fuchs' dystrophy in people in their 30s and 40s, the disease rarely affects vision until people reach their 50s and 60s.

• The condition was first described by Austrian Ernst Fuchs (1851–1930), after whom it is named.

• Missense mutations in COL8A2 • Early-onset Fuch dystrophy

3. The lens: Cataracts (백내장) • 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.

• Age-related cataract: 가장 흔함

10

Cataract. The white appearance of the

pupil in this eye is due to complete

opacification of the lens (“mature cataract”).

• Pathogenesis: - Several factors can promote the

formation of cataracts, including: a. long-term exposure to ultraviolet

light b. exposure to ionizing radiation,

secondary effects of diseases such as diabetes

c. hypertension and advanced age, or trauma (possibly much earlier)

d. they are usually a result of denaturation of lens protein.

- Genetic factors are often a cause of congenital cataract, 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.

- Atopic or allergic conditions are also known to quicken the progression of cataracts, especially in children.

- Cataracts can also be caused by iodine deficiency.

• Pathology: a.Age-related cataracts: 가장 흔함 b. Incipient cataracts (초기 백내장) c. Mature cataracts (성숙 백내장) d.Hypermature cataracts (과성숙

백내장) e.Phacolytic glaucoma (수정체팽

대 녹내장)

11

• Treatments: a.Non-surgical: Topical treatment

(eye drops) with the less well-known antioxidant N-acetylcarnosine

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

b. Surgical: - 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).

12 12

4. The Uvea (포도막) • Uveitis (포도막염):

• Iritis (홍채염):

Hypopyon in anterior uveitis, seen as yellowish exudate in lower part of anterior chamber of

• Cyclitis (섬모체염): • Iridocyclitis (홍채-섬모체염): • Posterior synechiae (홍채후 유착):

adhesions that develop between the iris & the lens.

• Peripheral anterior synechiae (말초성 홍채전 유착):

13

1) Sympathetic ophthalmitis (SO, 교감신경성 눈염증) is an autoimmune uveitis

• An autoimmune, granulomatous uveitis of both eyes following trauma to one eye.

• It can leave the patient completely blind.

• Symptoms may develop from days to several years after a penetrating eye injury.

• Clinical features: - Floating spots and loss of

accommodation are among the earliest symptoms.

- The disease may progress to severe iridocyclitis with pain and photophobia.

- ~80% of cases, the uveitis appears within 2–12 weeks after injury, and 90% occur within 1 year from the time of injury.

• Definitive prevention of SO requires prompt (within the first 7 to 10 days following injury) enucleation of the injured eye.

3) Sarcoidosis (사르코이드증) often affects the eye • Sarcoidosis: a disease in which

abnormal collections of chronic inflammatory cells (granulomas) form as nodules in multiple organs

• Sarcoidosis in the eye: - Manifestations in the eye include

uveitis, uveoparotitis, and retinal inflammation, which may result in loss of visual acuity or blindness.

- The combination of anterior uveitis, parotitis, VII cranial nerve paralysis and fever is called uveoparotid fever, and is associated with Heerfordt-Waldenstrom syndrome.

- Development of scleral nodule associated with sarcoidosis have been observed.

- Mikulicz syndrome:

5. The Retina (망막)

1) Retinal hemorrhage (망막출혈) has different causes

• Causes: hypertension, DM, & central retinal vein occlusion.

• Retinal hemorrhages can also occur due to shaking, particularly in young infants (shaken baby syndrome) or from severe blows to the head.

• Treatment:

- Retinal hemorrhages, especially mild ones not associated with chronic disease, will normally resorb without treatment.

- Laser surgery is a treatment option which uses a laser beam to seal off damaged blood vessels in the retina.

- Anti-vascular endothelial growth factor (VEGF) drugs like Avastin and Lucentis.

2) Occlusive retinal vascular disease (폐쇄망막 혈관병) is an important cause of blindness

A. Central retinal artery occlusion (CRAO, 망막중심 동맥폐쇄)

• Central retinal artery occlusion is a disease in which the respective artery has been occluded by various possible etiologies.

• The most common etiology is that of carotid artery atherosclerosis.

• Cherry-red spot (채리적색 반점):

• Amaurosis fugax (일과성 흑내장):

• No good therapy currently exists.

B. Central retinal vein occlusion (망막중심 정맥 폐쇄)

• Results in flame-shaped hemorrhages in the nerve-fiber layer of the retina, especially around the optic disc.

• Vision is disturbed but may recover surprisingly well.

• It can also cause glaucoma. 14

3) Hypertensive retinopathy (고혈압 망막병증) relates to the severity of hypertension • damage to the retina and retinal circulation due to high blood pressure

(i.e. hypertension). • Arteriovenous nicking (망막동정맥혈관협착) & necrotizing arteriolitis

with fibrinoid necrosis & thrombosis

15

Hypertensive retinopathy. Various abnormalities develop within the retina in hypertension. The commonly associated arteriolosclerosis affects the appearance of the retinal microvasculature. Light reflected from the thickened arteriolar walls mimics silver or copper wire. Blood flow through the retinal venules is not well visualized at the sites of arteriolar:venular crossings. This effect is due to a thickening of the venular wall rather than to an impediment to blood flow caused by compression; the column of blood proximal to the compression is not wider than the part distal to the crossing. Impaired axoplasmic flow within the nerve fiber layer, caused by ischemia, results in swollen axons with cytoplasmic bodies. Such structures resemble cotton on funduscopy (“cotton-wool spots”). Hemorrhages are common in the retina, and exudates frequently form a star around the macula.

4) Diabetic retinopathy (당뇨망막병증) is primarily a vascular disease

• caused by complications of diabetes, which can eventually lead to blindness.

• It is an ocular manifestation of systemic disease which affects up to 80% of all patients who have had diabetes for 10 years or more.

• The longer a person has diabetes, the higher his or her chances of developing diabetic retinopathy.

16

Diabetic retinopathy. In diabetic retinopathy, the microvasculature is abnormal. Arteriosclerosis narrows the lumen of the small arteries. Pericytes are lost, and the endothelial cell-to-pericyte ratio is greater than 1. Capillary microaneurysms are prominent, and portions of the capillary network become acellular and show no blood flow. The basement membrane (BM) of the retinal capillaries is thickened and vacuolated.

Diabetic Retinopathy and

Cataract

당뇨 망막병증

30년 동안 IDDM 환자의

10%가 시력을 잃음

18

Diabetic retinopathy. A. The ocular fundus in a patient with background diabetic retinopathy. Several yellowish “hard” exudates (straight arrows), which are rich in lipids, are evident, together with several relatively small retinal hemorrhages (curved arrows). B. A vascular frond (top half) has extended anteriorly to the retina in the eye with proliferative diabetic retinopathy.

Normal vision

The same view with

diabetic retinopathy.

19

Effects of diabetes on the eye.

20

A. Background (nonproliferative) diabetic retinopathy [당뇨배경성 (비증식성) 망막병증]

• This stage exhibits venous engorgement, small hemorrhages (dot & bot hemorrhages), capillary microaneurysms, & exudates.

• Nonproliferative diabetic retinopathy shows up as cotton wool spots, or microvascular abnormalities or as superficial retinal hemorrhages.

• Exudative diabetic retinopathy (삼출 당뇨망막병증):

• Waxy exudates (밀랍성 삼출물):

B. Proliferative retinopathy (증식 망막병증):

• As the disease progresses, severe nonproliferative diabetic retinopathy enters an advanced, or proliferative (PDR), stage when blood vessels proliferate (i.e. grow).

• The lack of oxygen in the retina causes fragile, new, blood vessels to grow along the retina and in the clear, gel-like vitreous humour that fills the inside of the eye.

• Without timely treatment, these new blood vessels can bleed, cloud vision, and destroy the retina.

• Treatments: - Laser phototherapy

(photocoagulation) & strict glycemic control early in the course.

- Modified grid laser photocoagulation

- Panretinal photocoagulation - Intravitreal triamcinolone

acetonide

21

5) Retinal detachment (망막박리) separates the sensory retina from the pigment epithelium

• A disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness.

• It is a medical emergency.

• Types:

a. Rhegmatogenous retinal detachment (열공 망막박리):

• A rhegmatogenous retinal detachment occurs due to a break in the retina (called a retinal tear) that allows fluid to pass from the vitreous space into the subretinal space between the sensory retina and the retinal pigment epithelium.

Slit lamp photograph showing retinal detachment.

• Retinal breaks are divided into three types - holes, tears and dialyses.

- Holes (구멍) form due to retinal atrophy especially within an area of lattice degeneration.

- Tears (찢어짐) are due to vitreoretinal traction.

- Dialyses (투석) which are very peripheral and circumferential may be either tractional or atrophic, the atrophic form most often occurring as idiopathic dialysis of the young.

22

b. Tractional retinal detachment (견인 망막박리) - A tractional retinal detachment

occurs when fibrous or fibrovascular tissue, caused by an injury, inflammation or neovascularization, pulls the sensory retina from the retinal pigment epithelium.

c. Exudative, serous, or secondary retinal detachment (삼출 망막박리)

- Occurs due to inflammation, injury or vascular abnormalities that results in fluid accumulating underneath the retina without the presence of a hole, tear, or break.

- Although rare, exudative retinal detachment can be caused by the growth of a tumor on the layers of tissue beneath the retina, namely the choroid.

- This cancer is called a choroidal melanoma.

6) Retinitis pigmentosa (망막색소변성) is a heritable cause of blindness

Retinitis pigmentosa. A. Fundus photograph of the retina of a patient with pigmentary retinopathy (retinitis pigmentosa) shows attenuated retinal vessels and foci of retinal pigmentation (arrows). B. Microscopic appearance of a severely degenerated retina in pigmentary retinopathy. Note the focal accumulations of pigmented, brown cells (derived from retinal pigmented epithelium) within the retina.

23

Fundus of patient with retinitis pigmentosa, mid stage (Bone spicule-shaped pigment deposits are present in the mid periphery along with retinal atrophy, while the macula is preserved although with a peripheral ring of depigmentation. Retinal vessels are attenuated.)

• An inherited, degenerative eye disease that causes severe vision impairment and often blindness.

• Sufferers will experience one or more of the following symptoms:

a. Night blindness or nyctalopia b. Tunnel vision (no peripheral

vision) c. Peripheral vision (no central

vision) d. Latticework vision e. Aversion to glare f. Slow adjustment from dark to

light environments and vice versa

g. Blurring of vision h. Poor color separation i. Extreme tiredness.

The same view with tunnel vision from retinitis pigmentosa. The blackness surrounding the central image does not indicate darkness, but rather a lack of perceived visual information.

24

7) Macular degeneration (황반변성) is mostly age-related. • A medical condition which usually

affects older adults and results in a loss of vision in the center of the visual field (the macula) because of damage to the retina.

• It occurs in "dry" and "wet" forms. • It is a major cause of blindness

and visual impairment in older adults (>50 years).

• Macular degeneration can make it difficult or impossible to read or recognize faces, although enough peripheral vision remains to allow other activities of daily life.

• Starting from the inside of the eye and going towards the back, the three main layers at the back of the eye are the retina, which contains the nerves; the choroid, which contains the blood supply; and the sclera, which is the white of the eye.

Picture of the fundus showing intermediate

age-related macular degeneration.

The same view with age-related macular

degeneration

25

The normal retina. Constituents of the normal retina are arranged in distinct layers. These include the nerve fiber layer (NFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), inner segments (IS) and outer segments (OS) of the photoreceptors and the retinal pigment epithelium (RPE). The axons from the ganglion cells enter the nerve fiber layer and converge toward the optic nerve head. The inner retina contains arteries and veins. The retina is thinnest at the center of the macula, where bare photoreceptors rest on the retinal pigment epithelium. Only one cell thick in most of the retina, the ganglion cell layer is multilayered at the macula.

Cherry-red macula. A cherry-red spot appears at the macula in several lysosomal storage diseases that are characterized by intracytoplasmic accumulations within the retinal ganglion cells, such as Tay-Sachs disease, in which a particular ganglioside is stored (GM2-ganglioside). The macula develops this appearance because the pallor created by the deposits within the multilayered ganglion cells enhances the visibility of the underlying normal choroidal vasculature.

26

6. The optic nerve (시각신경) 1) Optic nerve head edema (시각

신경 유두부종) often reflects increased intracranial pressure

• Papilledema (유두부종) is optic disc swelling that is caused by increased intracranial pressure.

• The swelling is usually bilateral and can occur over a period of hours to weeks.

• Unilateral presentation is extremely rare.

• Papilledema is mostly seen as a symptom resulting from another pathophysiological process.

• In intracranial hypertension, papilledema most commonly occurs bilaterally.

• When papilledema is found on fundoscopy, further evaluation is warranted as vision loss can result if the underlying condition is not treated.

• Further evaluation with a CT or MRI of the brain and/or spine

Chronic papilledema. The optic nerve head (bracket) is congested and protrudes anteriorly toward the interior of the eye. It has blurred margins, and the vessels within it are poorly seen. In contrast to acute papilledema, the veins are not so congested, and hemorrhage is not a feature.

Hemorrhage in papilledema. The optic nerve head is markedly congested, with dilated veins and a blurred margin. A small hemorrhage is evident within the optic nerve head at its junction with the retina (straight arrows). Several small “cotton-wool spots” are present within the adjacent retina (curved arrows).

27

Optic atrophy. The margin of the optic

nerve head is sharply demarcated from the

adjacent retina. Because the myelinated

axons in the optic nerve are markedly

diminished, the optic nerve head appears

much whiter than normal.

2) Optic atrophy (시각신경 위축) is a thinning of the optic nerve caused by loss of axons within its substance • Optic atrophy: the loss of some or

most of the fibers of the optic nerve.

• In medicine, "atrophy" usually means "shrunken but capable of regrowth", so some argue that "optic atrophy" as a pathological term is somewhat misleading, and the term "optic neuropathy" should be used instead.

• In short, optic atrophy is the end result of any disease that damages nerve cells any where between the retinal ganglion cells to the lateral geniculate body(anterior visual system).

• Glaucomatous cupping (녹내장 유두 패임):

• Leber hereditary optic neuropathy:

녹내장 (Glaucoma)

(Iris)

(Schlemm canal)

29

Pathogenesis of glaucoma. The anterior segment of the eye is affected differently in various forms of glaucoma. A. Structure of the normal eye. B. In primary open-angle glaucoma, the obstruction to the aqueous outflow is distal to the anterior chamber angle, and the anterior segment resembles that of the normal eye. C. In primary narrow-angle glaucoma, the anterior chamber angle is open, but narrower than normal when the pupil is constricted (C1). When the pupil becomes dilated in such an eye, the thickened iris obstructs the anterior chamber angle (C2), causing increased intraocular pressure (IOP). D. The anterior chamber angle can become obstructed by a variety of pathologic processes, including an adhesion between the iris and the posterior surface of the cornea (peripheral anterior synechiae).

7. Glaucoma (녹내장)

Acute angle closure glaucoma of the right eye. Note the mid sized pupil, which was nonreactive to light, and injection (nonuniform redness) of the conjunctiva.

• The most common cause of preventable blindness in the US.

• In most cases, glaucoma is produced by ocular hypertension (눈 고혈압)

• It is normally associated with increased fluid pressure in the eye (aqueous humour).

30

• An eye disease in which the optic nerve is damaged in a characteristic pattern.

• This can permanently damage vision in the affected eye(s) and lead to blindness if left untreated.

• The term "ocular hypertension" is used for people with consistently raised intraocular pressure (IOP) without any associated optic nerve damage. Conversely, the term 'normal tension' or 'low tension' glaucoma is used for those with optic nerve damage and associated visual field loss, but normal or low IOP.

• Causes: a. Dietary: caffeine increases IOP. b. Ethnicity & gender: Asian; Inuit; Women: men = 3:1 c. Genetics d. Others

The same view with

advanced vision loss

from glaucoma

Optic nerve head in glaucoma. The anterior part of the optic nerve is depressed (“optic cupping”; arrows), and the blood vessels crossing the margin of the optic nerve head are displaced to the nasal side.

알아야 막을 수 있다. 녹내장!(2012.12.18. 조선일보)

•안압 상승이 가장 큰 원인

•안압 정상인 녹내장 환자 더 많다

•녹내장 자각 증상 알아차리기 어려워

•어떤 사람이 잘 걸리는가?: 고혈압, 심혈관질환 보유자

•정기 안과 검진이 큰 도움

•녹내장 예방 및 관리법

- 목을 조이거나 눈을 압박하지 않는다

- 얼굴 빨개지는 행동을 피한다 - 어두운 곳에서 눈 사용 금물 - 물은 한 번에 많이 마시지 않는다 - 심리적 스트레스와 과도한 음주

31

32

• Several different types: 1)Congenital glaucoma (선천 녹내

장, infantile glaucoma, buphthalmos) results from developmental anomalies

• X-linked • Boys (65%) • Several genes are involved. 2) Primary open-angle glaucoma

(원발 개방각 녹내장) is the most frequent type of glaucoma

• Major cause of blindness in the US

• 1~3% of the population older than 40 years of age

• Occurs principally in the sixth decade.

• Open-angle: anterior chamber angle is open and appears normal

3) Primary closed-angle glaucoma (원발 폐쇄각 녹내장) is associated with a shallow anterior chamber

• Occurs after 40 years of age

• Closed-angle: anterior chamber is shallower than normal, and the angle is abnormally narrow

• Caused by contact between the iris and trabecular meshwork, which in turn obstructs outflow of the aqueous humor from the eye.

• Acute closed-angle glaucoma is an ocular emergency

• Treatment: within the first 24 to 48 hours, ocular hypotensive treatment should be started.

4) Secondary glaucoma (속발 녹내장) is usually unilateral

• Caused by inflammation, hemorrhage, & neovascularization of the iris & adhesions.

• Anterior chamber angles may be open or closed.

• Usually unilateral

33

5) Low-tension glaucoma (저안압 녹내장) is not associated with increased intraocular pressure • An entity in which the

characteristic visual-field defect & all of the ophthalmoscopic features of chronic open-angle glaucoma occur without an increase in intraocular pressure.

• May be hypersensitive to normal intraocular pressure, many cases of low-tension glaucoma probably represent optic nerve head infarction.

1. 정상인 눈에 비친 풍경=모든 사물이 선명하게 보인다.

2. 백내장 환자 눈에 비친 풍경=수정체 노화로 모든 사물이 뿌옇게 보인다.

3. 황반변성 환자 눈에 비친 모습=시신경 중심부 손상으로 가운데가 까맣게 보인다.

4. 녹내장 환자 눈에 비친 풍경=시신경 주변부 손상으로 주변이 깜깜하게 보인다.

8. Ocular neoplasms

1) Malignant melanoma (악성흑색종) arises from melanocytes in the uvea

• a cancer (melanoma) of the eye involving the iris, ciliary body, or choroid (collectively referred to as the uvea).

• The most common primary intraocular malignancy.

• Tumors arise from the pigment cells (melanocytes) that reside within the uvea giving color to the eye.

• These melanocytes are distinct from the retinal pigment epithelium cells underlying the retina that do not form melanomas.

• Primary treatment:removal of the affected eye (enucleation)

• Advances in radiation therapies: brachytherapy

34

Malignant melanoma. A. A mushroom-shaped melanoma of the choroid is present in this eye (arrow). Choroidal melanomas commonly invade through the Bruch membrane and result in this appearance. B. Photomicrograph of a heavily pigmented melanoma of the choroid depicting epithelioid tumor cells with prominent nucleoli.

35

Retinoblastoma. A. The white pupil (leukocoria) in the left eye is the result of an intraocular retinoblastoma. B. This surgically excised eye is almost filled by a cream-colored intraocular retinoblastoma with calcified flecks. C. Light microscopic view of a retinoblastoma showing Flexner-Wintersteiner rosettes characterized by cells that are arranged around a central cavity.

2) Retinoblastoma (망막모세포종) • a rapidly developing cancer that

develops in the cells of retina, the light-detecting tissue of the eye.

• In the developed world, Rb has one of the best cure rates of all childhood cancers (95-98%), with more than nine out of every ten sufferers surviving into adulthood.

• Rb1 gene: 13p • There are two forms of the

disease, a heritable form and non-heritable form (all cancers are considered genetic in that mutations of the genome are required for their development, but this does not imply that they are heritable, or transmitted to offspring).

• ~55% of children with Rb have the non-heritable form (sporadic).

• rare and affects approximately 1 in 20,000~34,000 live births, but it is the most common inherited childhood malignancy.

• Pathology: In children with the heritable genetic form of retinoblastoma there is a mutation on chromosome 13, called the RB1 gene. The genetic codes found in chromosomes control the way in which cells grow and develop within the body. If a portion of the code is missing or altered (mutation) a cancer may develop.

• Treatments: - Varies from country to country. - The priority is to preserve the life

of the child, then to preserve vision, and then to minimize complications or side effects of treatment.

- Many treatment options: chemotherapy, cryotherapy, radioactive plaques, laser therapy, external beam radiotherapy and surgical removal of the eyeball (enucleation).

고령화 실명 급증… 길 나서면 선글필착 명심하라 [동아일보 (2012. 4. 9)]