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GENERAL INTRODUCTION

Cataract is a clouding of the lens inside the eye which leads to a decrease in vision.it is the most

common cause of blindness and it is conventionally treated with surgery. Visual loss occurs because

opacification of the lens obstructs light from passing and being focused on the retina at the back of

the eye.

The origin is from Greek word kataraktes, meaning something that is rushing or swooping down. Its

a derivative of katarassein, from katadown plus arasseinstrike, smash.

The eye is the organ of the sight situated in the orbital cavity. The eye ball contains the orbital

apparatus of the visual system. The space between the eye and the orbital cavity is occupied by fatty

tissue. The bony wall of the orbit and the fat help protect the eye from injury

Structurally, the two eyes are separate but they function as a pair.it is possible to see only with

one eye, but three-dimensional vision is impaired when only one eye is used specially in relation tothe judgement of distance,

The eyeball is made up of three layers, however there is an additional loose connective tissue

layer that surrounds the eyeball, allowing its movement within the orbit. The loose connective tissue

layer is composed posteriorly of bulber fascia.

ANATOMY OF THE EYE

The eye is almost spherical in shape and is about 2.5cm in diameter, the volume of an eyeball is

approximately 7cc.

The eyeball is made up of three layers which are

1. Fibrais layer (Outer coat): It consists of the cornea and sclera. Also made up of the limbalzone

2. Vascular layer (middle coat): it consists of the choroid ciliary body and the iris.3. Inner layer (inner coat): it consists of the retina, that has both optic and non-visual part

1) Fibrous layera. The cornea is the transparent part of the fibrous coat covering the anterior one sixth of the

eye ball. It composes the outer wall of the eye. The structure of the collagen fibrils in the

cornea stoma and descements membrane is important in the relative resistant property of

the cornea.

In addition, the cornea serves as the principal refractive surface, the transparency is unique

and essential for good visual acuity and this condition is actively maintained by the cornea

cells especially the cornea epithelial cells

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EPITHELIUM

The cornea l epithelium is the outermost part of the cornea which is composed of stratified,

squamous and non-keratinised epithelial cells. The thickness of the cornea epithelium is 50-

90micrometer and consist of five to six layers of corneal epithelial cells. The deepest of this is called

basal cell layers. This layer is the germinate focus of the corneal epithelial cells divide anddifferentiate into the upper layer of the corneal epithelium.

The second layers, wing cells consists of polyhedral cells, is located between the most superficial

and inner layer of the corneal epithelium, they move to the superficial layer and the outer most 1to

2 layer are called superficial cells,

The metabolism of the corneal epithelial cells is active. The epithelial cells contain glycogen

granules in their cytoplasm, especially in the wing and superficial cells. The content of the glycogen

decreases in bacterial infection, wound healing and soft contact lens wear, the corneal epithelial

cells contains a fine network of intermediate and action filament.

The most superficial cells of the epithelium has microvilli and glycocalyx on its surface. Thesurface is important in connecting and stabilising the tear film on the superficial corneal epithelial

cells.

The corneal epithelial cells have special adhesion molecules which are important in cell-cell and

cell-basement attachment, Adhesion of the neighbouring epithelial cells is almost maintained by

desmosomes and tight junctions because the junctions between the epithelial cells is so tight , it

serves as a mechanical barrier to micro-organism and foreign bodies. However, the corneal

epithelium has some permeability to small molecules including glucose, sodium, O2 and CO2

The basal cells have numerous hemidesmosomes at the basal side which help in attachment to

basement membrane of the corneal epithelium

b. ScleraThe sclera is the main part of the outer Wll of the eye. It is the white part of the eyeball. Its opacity is

attributed to the high water content of 68%, the derangement of the collagen fibres, composing of

sclera.

The major roles of the sclera are to protect the intraocular tissue and to maintain the shape of the

eyeball. As the sclera is a relatively tough tissue, it consists of collagen, elastic fibers, glycoproteins,

and scattering fibrocytes and fibroblasts. It serves to maintain intraocular pressure even whenmechanical stress is added

c. Limbal zoneThe limbal zone is a transitional are between the corneal and conjuctiva. The characteristic of the

limbal zone is the deficiency in Bowmans layer or goblet cells.Clinically, this layer is observed as the

circular area with palisading tissues called palisades vogt

Immunohistochemically study has revealed that cytokeratin typical of differentiated cells are

expressed by corneal epithelial cells and suprabasal imbal epithelial cells, while basal limbal cells are

negative for these cytokeratins and positive for a group of acidic cytokeratins with the antibody AE1,

which recognises a 48kda keratin expressed in hyperproliferative states.

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The basal epithelial cells are by very slow division of stem cells which lie at the basal cell layer of the

limbal epithelium. Histologically, the stem cell of the corneal epithelium in the limbal zone is small

with prominent nucleus ultrastructuraly they show large nucleoli, a lot of bundles of intermediate

filament and many desmosomes and hemidesmosomes, which suggest the active metabolism of

stem cells.

Clinically, limbal epithelium is damaged in such conditions as alkali burn and inflammatory disease

like permphigod

2. MIDDLE CASCULAR LAYER

a. ChoroidThis is a dark reddish brown layer between the sclera and retina, form the largest part of the

vascular layer of the eyeball and lines most of the sclera, it extends from the ora serrate up to the

aperture of the optic nerve in the sclera. Within this pigmented and dense vascular bed, larger

vessels of the vascular lqminq located externally (near the sclera).the finest blood vessels the

(capillary lamina of the choroids or chricopilaris) are innermost, adjacent to the vascular lightsensitive layer of the retins which it supplies with oxygen and nutrients. Engorged with blood in life,

the layer is responsible for the red eye reflection that occurs in flash photography.The choroids is

continuos anteriorly with the ciliary body.The choroids attaches firmly to the pigment layer of the

retina, but it can easily be stripped from the sclera

The choroids can also be said to have the following histological features

1. Chorocapillary layer capillaries arranged in one plane, fenestrated type2. Bruchs membrane, 3-4 micron thick amorphous hyaline membrane that the pigmented

epithelial rests upon

b. Ciliary bodyThe ciliary body is triangular in shape with base forward. The iris is attached to the middle of the

base. The ciliary body is mascular as well as vascular and it connects the choroids with the

circumference of the iris. It provides attachment of the lens; contraction and relaxation of thr

smooth muscle of the ciliary body controls thickness of the lens. Folds on the internal surface of the

ciliary body, the ciliary processes, secrete aqueous humor. Fibres of the ciliary processes are

composed of oxytalin fibres which extend from these projections and attach to the lens. The ciliaryprocesses are lined with two layers of columnar cells as body. The columnar cells are joined by tight

junctions and desmosomes and actively transport ions from the plasma into the posterior chamber

forming the aqeous humour of the internal eye.

The anterior chamber of the eye is the space between the cornea anteriorly and the iris/pupil

posteriorly.The ciliary body consists of nonstriated muscle fibres (ciliary muscles), stroma and

secretory epithelial cells. It consists of two main parts namel pars plicata and pars plana

C. Iris

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It literally lies on the a nterior surface of the lens. It is a thin contractile diaphragm wiith a central

aperture, the pupil, for transmitting light. It is colored, free, circular. It divides the anterior segment

of the eye into anterior and posterior chambers which contain aqueous humor secreted by the

ciliary body. It consists of endothelium, stroma, pigmented cells and two groups of plain muscle

fibres, one circular (sphincter pupillae) and the other radiating (dialator pupillae), The anterior

aspect of the iris is lined with a double layer of pigmented epithelium

3. INNER RETINA LAYERThe retina consists of two functional parts with distinct location:

a. An optic part: it is sensitive to visual light rays and has two layers which are, the neural layerand the pigment cell layer which consists of a single layr of cells

b. The non-visual retina: is an anterior continuation of the pigment cell layer and a layer ofsupporting cells over the ciliary body and posterior surface of the iris respectively.

The retina is composed of ten layers of nerve cells and nerve fibres lying on a pigmented epithelial

layer. Maculalutea is a yellow area of the retina situated in the posterior part with a central

depression called fovea centralis. It is the most sensitive part of the retina

The eye is also made up of some accessory structures which include

a. Eyebrowb.

Eyelid and eyelashesc. Lacrima apparatus- it consists of:

i. Lacrimal gland and its ductsii. Accessory lacrimal glandsiii. Lacrimal canaliculliiv. Lacrimal sacv. Nasolacrimal ductd. Extra ocular muscles of the eye: they arei. The medial rectus muscleii. The superior rectus muscleiii. The inferior rectus muscleiv. The superior oblique musclev. The inferior oblique muscle

The blood supply to the eye is by the short and long ciliary arteries and the central retinal artery and

thes are branches of the ophthalmic artery

The bvenous drainage is by the short ciliary veins, anterior ciliary veins, 4 vortex veins and the

central retinal vein. They eventually empty into the cavernous sinus

The nerve supply tonthe eye is by 3 types of nerves

1. The motor nerve2. The bsensory nerve3. The autonomic nerve

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1.5 LENS

a. Anatomy of The Lens

A lens is merely a carefully ground or molded piece of trans[arent material which refracts lights

rays in such a way as to form an image. Lenses can be thought of as a series of tiny refracting prism,

each of which refracts lights to produce their own image when these prisms act together, they

produce a bright image focused at a point

Also, the lens could be said to be a transparent, biconvex structure in the eye that, along with

the cornea,helps to refract light to be focused on the retina. The lens by changing shape, functoons

to vhange the focal distance of the eye so that it can focus on objects at various distance thus,

allowing a sharp real image of the object of interest to be formed on the retina. This adjustment of

the lens is called accommodation

In humans,the refractive power of the lens in the natural environment is approximately 18

dioptre, roughly one- third of the eyes total power

POSITION,SIZE AND SHAPE OF THE LENS

The lens is located in the anteriror segment of the eye.Anterior to the lens is the iris which

regulates the amount of light entering the eye.The lens is suspended in place by the zonular fibres,

which attach to the lens near its equatorial line and connect the lens to the capillary body.Posterior

to the lens is the vitreous body, which along with the aqyueous humour on yhe anterior surface,

bathes the lens, the lens has an ellipsoid, biconvex shape. The anterior surface is less 10mm in

diameter and has an axial length of 4mm, though it is important to note that the size and shape can

change due to accommodation and because the lens continues to grow through out a person

lifetime.

LENS STRUCTURE AND FUNCTION

The lens is composed of three main parts: The lens capsule, the lens epithelium, and the lens fibers

LENS CAPSULE

It forms trhe outermost layer of the lens.The lens capsule is a smooth, transparent basement

membrane that completely surrounds the lens. Kits synthesized by the lens epithelium and its main

component are type iv collagen and sulfated glycosaminglycon (GAGs). The capsule is veryelastic.The zonular fibers connect the lens capsule to the ciliary body. The capsule varies from 2-23

micrometres in thickness, being thickestr near the equator and thinnest near the posterior pole. The

lens capsule may be involved with the higher anterior curvative than posterior of the lens.

Lens Epithelium

The lens epithelium, located in the anterior portion of the lens between the lens capsule and the

lens fibers, is a simple cuboidal epithelium. The cells of the lens epithelium regulate most of the

homeostatic functions of the lens. As ins, nutrients, and liquid enter the lens from the aqueous

humor, Na+/K+ Atpase pumps in the lens epithelial cells pump ions out of the lens to maintain

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The lens continues to grow after birth with the new secondary fibers being added as outer layers.

New lens fibers are generated from the equatorial cells of the lens epithelium, in a region referred to

as the germinative zone. The lens epithelial cell elongate, lose contact with the capsule and

epithelium, synthesize crystalline, and then finally lose their organelles as they become mature lens

fibers. From development through early adulthood, the addition of secondary lens fibers results in

the lens growing more ellipsoid in shape; after about age 20, however the lens grows rounder with

time

CHAPTER TWO

Introduction

Morphological Classification

It is based on morphological (size,site and appearance) cataract can be classified as capsular,

subscapular, cortical, supranulear, nuclear lamellar and structural cataract. The individual, location

and configuration ofeach type of morphological cataract is described here.

Classification Of Cataract

A.

CAPSULAR CATARACTAcquired capsular opacities may occur in low and miller syndrmes, thermal cataract,

pseudoexfoilation syndrome, gold toxicity and vissious ring.

Common form of capsular opacity is polar cataract which develops in anterior, posterior

and bipolar foms. The anterior polar cataract is more frequent. The opacity is generally

discshaped and most commonly lies in the anterior subscapular clear zone.

Capsular opacities usually remain static but under lying cortical opacities may develop

B. SUBCAPSULAR CATARACTSubscapsular cataract usually develop asa aresult of damage to subscapsular epithelium

In posterior subcapsular cataract developments, first change that occurs is the posterior

migration of the epithelial cells. Subscapular cataracts tend to deteriorate during the period

of months if the initial trauma was severe or if the stimulating cause is not removed caba

C. CORTICAL CATARACTCongenital cortical opacities are common and dont usually interfere with vision. These

opacities may be white or of deep blue hue.

Senile cortical cataract (cuneiform cataract) is the most common cataract is acquired

type. Its site of origin in adjascent to the subcapsular epithelium

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D. SUPRANUCLEAR CATARACTDeep cortical cataracts like coronary in conginental type may be separately classified as

supranuclear catatract. The opacities are of round contour and are associated with contour

changes which may be white or cerulean

E. NUCLEAR CATARACTCongenital opacities are invariably of nuclear type because there is no cortex in the lens at

the time of birth.

Congenital nuclear opacities occur in rubella, glactoemia and cataract centralis

pulverulenta in which the entire embryonic nucleus is opaque. Histologically, there is a sharp

demarcation between the homogenous nucleus and the liquefied or fragmental cortex

F. LAMELLAR (ZONULAR) CATARACTLamellar cataract is invariably congenital as it involves one lamella of the fetal or nuclear

zones so that it encircles the lens both anteriorly and posteriorly forming and apparenthollow disc. It usually consist of manby white dots. This opacity develops as a result of insult

that affects the developing lens fibers for a specific period of time

G. SUTURAL CATARCTThese are frequent, congenital Y-shaped opacities within the lens nucleus as the Y-shaped

stutures are formed earlier than any others. They depict the line intersection of primary lens

fibers and form the anterior and posterior borders of the embryonic nucleus

CLASSIFICATION ACCORDING TO MATURITY

1. Immature CatarctImmature cataract is defined as that in which scattered opacities are separated by clear

zones. Lens appears grey in colour

2. Intumescent CataractIn yhis type of cataract the lens becomes swollen by imbibed water. It can be immature

or mature.The anterior chamber becomes shallow

3. Mature CatarctIn this type of cataract, the entire cortex becomes opaque qhite. The vision is sharply

reduced to perception of hand movement only. On fundal retralumination no fundal

glow is visible

4. Hypermature CataractThis is a mature cataract which has become smaller and has a wrinkled capsule due to

leakage of water out of the lens. There may be two types of hypermature cataract

a. Hypermature Moragnin CataractIn this type of cataract the total liquefaction of the cortex allow the nucleus to sink

inferiorly. There maybe deposition of calcium on the lens capsule

b. Hpermature Sclerotic Cataract

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The lens becomes flatter, the capsule becomes thick. Cataract appears brownish

ETILOGICAL CLASSIFICATION

1. Congenital CataractIt develops due to some disturbances in the normal growth of the lens.

Therefore in congenital cataract the opacity is limited to either embryonic or

fetal nucleus. Certain factors are associated with congenital cataract

These are

a. Hereditry factorsb. Material factorsc. Fetal factorsd. Idiopathic factors

2. Developmental cataractDevelopmental cataract may occur from infancy to adolescence. Therefore, such

cataract may involve infantile or adult nucleus, deeper parts of the cortex or

capsule. Its quantity increase with age.

Developmental cataract assumes to the most variegated forms and its

common in its minor manifestations various types of developmental cataracts

are as follows:

a. Punctuate cataractb. Coronary cataractc. Anterior polar cataract (delayed formation of anterior chamber)d.

Posterior polar cataract

e. Zonular cataract3. Acquired Cataract

In this type of catatract opacification occurs due to degeneration of already

formed normal lens fibers. The common varieties of acquired cataract are as

follows:

i. Senile cataractii. Senile nuclear cataract

4. Metabolic cataractThey in clude

a. Diabetic cataract: Two types of cataract are associated with diabetes andthey are

- Senile cataract in diabetic patients tends to develop at an earlier ageand progress more rapidly than the usual cataract

- True diabetic cataract or osmotic cataract is although a rare conditionbut usually develops in youngadults due to osmotic overhydration of the

lens.

b. Galactosemic cataract: it is associated with autosomal recessive inborn errorof galactose metabolism a deficiency of galactose -1-phosphate uridyl

transferase. It occurs in two forms

- Classic Galactosemia deficiency of galactose-1-photosphate uridyltransferase

- Related disorder due to deficiency of galactokinse(GK)

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c. Galactokinase deficiency cataractd. Hypocalcemic cataract (Tetanic cataract)e. Nutritional cataratctf. Hypoglycemic cataract

5. Traumatic cataractBoth penetrating and non penetrating physical injuries can cause cataract

6. Toxic cataractThis has been reported in human beings following the local and systemic use of

certain drugs, exposure to irradiation and electrical current shock. Various

cataracts under this group are as follows:

a. Steroid induced cataract: prolonged use of systemic, topical and inhaledcorticosteroids is associated with the development of axial posterior

subscapular cataractb. Miotics-induced cataract: Long term use of miotics specially long acting

cholinesterase inhibitors may cause formation of tiny anterior subscapular

vacuoles and sometime more advanced opacities

c. Chlorpromazine induced cataract: Prolonged administration ofchloropromazine may lead to the deposition of finwe yellowish brown

granules under the anterior lens capsule

WHAT IS CATARACT?

The word cataract is used to definbe the opacification of the crystalline lens of the eye. In other

words any opacity in the lens or its capsule whether congenital or acquired is known as cataract.

When the transparency of the crystalline lens decrease enough to disturb vision, aclinically

significant cataract exists. The lens being an avascular structure, inflammatory disease cannot

develop in it. The most common disease of lens development of opacity of lens fibers leading to

cataract formation. The decrease in lens transparency and subsequent cataract formation is udually

the result of foci of light scattering or absorption in the axial part of the lens. The term cataract is

often used to refer to change in color of the lens as well as a decrease in its transparency.

FEATURES, SIGNS AND SYMPTOMS

Any opacity of lens may be present without producing any symtomps and may be discovered on

routine ocular examination. Common cataract symptoms are:

- Glare: One of the earliest visual disturbances with the cataract is glare orbright light intolerance

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- Uniocular Polyopia: Doubling or trebling of object is also one of the earlysymptoms. Occurs mainly due to irregular reraction by lens owing to

variable refractive index as a result of cataract oogenesis

- Image blur: Image blur occurs when the lens is not able to differentiate(resolve) and separate distinct objects. Patients are unable to tolerate

image blur as it interferers with their day to day activities.

- Distortion: In cataract patients the straight edges appear curved orwavy. This may even lead to image duplication

- Coloured halos and altered colour perception: sometimes cataractpatients complain of coloured halos due to breaking of white light into

coloured spectrum due to the presence of water droplets in the lens.

The yellowing of the lens nucleus gradually increase with age

- Black spots: Some cataract patients complain of perceiving black spots infront of the eye in their visual field. These spots are stationary

- Loss of vision: Visual degeneration in senile cataracts is usually painlessand gradually progressive process. Patients with central type of early

loss of vision such patients see better in the evening. While in patients

see better in the evening. While in patients with peripheral opacities,

visual loss is delayed and vision is improved in bright light when the

pupil is contracted patients with nuclear sclerosis complain f distant

vision deterioration due to the progressive index myopia.

Behavioural Changes

- Children suffering from congenital, traumatic or metabolic cataractsmay not be able to express their visual disturbances. In such patients

behavioural changes are indicative of a loss of visual acuity or binocular

vision may alert the intelligent parents and teachers to the presence of a

visual problem. Inability to see the blackboard or read with one eye and

sitting very close to television may be such symptoms. Also inability to

catch or hit a ball, pour water from the pitcher into the glass, sitting on

chair or bed are seen in such children

- Young adults suffering from cataract may frequently face the difficultywith night driving

Visual Acuity Testing

Through visual acuoity testing should be performed in every cataract patient. The level of visual

acuity is directly related to cataract maturation.

Leukokoria: Typical white pupil is seen in mature senile cataracts while in certain immature

cataracts, whitish gray or yellow patches are seen in the papillary area. Thesepathes are as a result

of light scattering from opacities situated in anterior subscapular or cortical zones

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WAYS OF DIAGNOSING CATARACT

- Diagnostic Tests For Cataracta. Snellen visual acuity for distance and near vision with appropriate glasses should be tested.b. Non-snellen visual acuity: Certain patients come with complaints of poor visual function

despite good snellen visual acuity. Cataracts may lead to decreased contrasts perceptionleading to visual dysfunction. Cataracts especially posterior subscapular and cortical may

cause debilitating glare. Several readily available commercial instruments can be used to

show the effect of glare on visual acuity in cataract patients

c. Lens and pupil examination: when a bright flashlight is used the direct and consensualpapillary responses are not affected by lens opacities are visible to the examiner if pupil size

is adequate.

d. Direct ophthalmoscopy: on direct ophthalmoscopy, nuclear cataracts are visible as lenswithin a lens when viewed against red fundal glow

e. Refraction and retinoscopy: Nuclear cataract patient shows index myopia in the early stages.It can be detected by routine refractive examinatiom patients can be corrected for years

wioth a stronger myopic distance glasses and standard reading glasses for near vision

Retinoscopy shall reveal the abnormal reflexes associated with lenticular opacities lenticonus

f. Ultrasonography: A-scan and B-scan ultrasonographies are standard methods for accuratelymeasuring the thickness and location of the lens opacities. B-scan ultrasonography is

specially helpful in evaluating abnormalities of posterior segment of the eye with a very

dense cataract. Secondary cataract formation in response to posterior segment tumors or

inflammation thereby necessitates the use of ultrsonography to ascertain the anatomical

state of the eye behind the lens.

POPULATION AT RISK

By saying *population at risk*. It refers to those at high risk or those prone to have cataract and they

canbe grouped as follows

- Toxic or drug induced cataract: Toxic cataract is common in individualsfollowing the local systemic use of certain drugs, exposure to radiation

and electrical current shock

a. Electrical cataract: Electrocution injury(passage of powerful electric current through thebody) may lead to cataract formation. Therefore, there is high risk of cataract in people that

worl with electric current or deal with it in their daily activity.

b. Microwaveinduced cataract: Exposure to microwave radiation at radar installations in anypersonnel for a long time may lead to cataract formation. Therfore microwave radiation is a

potential cataractogenic factor and thus this increase the risk of cataract formation in

microwave users both domestically, and industrially or otherwise

c. X-ray radiation cataract: Ionizing radiation (x-rays, gamma rays or neutrons) may lead tocharacteristic posterior subscapular. A little single dose of 300 to 400 rad may lead to

cataract development. Neuron and alpha beam produce greater ionization and pose the

greatest risk of cataract formation ionization and this, therefore increase the risk of cataractin radiologists and the patients undergoing the x-rays

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d. Infrared radiation cataract: (Glass blowers and glasses workers cataract). Prolongedexposure to infrared radiation may lead to exfoliation of the anterior lens capsule. Thus

increase the risk of cataract formation among infrared users and people that work around it.

e. Corticosteroids induced cataract: Usage of corticosteroid over a long period of time byindividual can lead to development of axial posterior subscapular cataract. The higher the

dose of the corticosteroid and the longer the usage of the drug, the more the chance to

develop cataract.

f. Chloropromazine-induced cataract: Prolonged administration of chloropromazine may leadto the deposition of fine yellowish brown granules under the anterior lens capsule therefore

forming cataract.

METABOLICALLY INDUCED CATARACT

a. Diabetes is a metabolic abnormality in which if not well controlled can cause somecomplications of which cataract can be formed. Therfore diabetics are at risk of cataract

formation if the diabetes is not well controlled. People with diabetes are twic as likely todevelop cataract than are people without

b. Cataract in fabrys disease is due to deficiency of the enzyme d-galactosidase A.c. Nutritional cataract: subscapular cataract have been shown to develop in patients with

anorexia nervosa. An earlier onset of subscapular cataract specially in people who have

alchol abuse developed duplutrens contracture has been oserved.

d. Cataract in wilsons disease: in born error copper metabolism results in Wilson disease>A characteristics opacity may develop in the anterior capsule region. Thus causing

cataract formation In such patients

AGE GROUP AT RISK

The frequency of cataract increase dramatically after age 65, but risk starts as from ages 40

upwards. Some people between age 40-50 can have an age-related cataract, but these cataract is

mild and do not yet affect vision

- RACE AT HIGHER RISK OF CATARACTFor the first time, a nine-year population study has demonstrated that people of African descent

have nearly twice the incidences of cataracts than Caucasians. In addition, the risk of a certain type

of cataract was more than three times higher in blacks than in white

- SOCIAL FACTORSa. Smoking

Tobacco is the leading preventable cause of disease, disability and premature death.

Cigarette smoking is a substantial source of intake of heavy metals and toxic mineral

elements, such as cadmium, aluminium, lead, mercury, all known to be poisonous in high

concentrations.

Tobacco smoke also contains numerous compounds withg oxidative properties, their

existence is linked to the pathogenesis of several common eye disorders, such as cataract

and age-related macular degeneration.

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b. AlcoholOne study reported thart both abstainers and heavy drinkers were more likely to have

cataract than moderate users, while another found that total abstainers were more likely to

have cataract than alcohol users

CHAPTER THREE

STEPS IN CATARACT FORMATION

The various steps in general mechanism of cataract formation are as follows:

Lens FIber OpacificationPreviously clear, superficially situated youngest lens fibers presenting subscapular clear

zone arear, are more prone to physical injuries like concussion, trauma and to metabolic

disturbances like diabetes, Due to this change many acquired cataracts associated withtrauma, diabetes and hyper parathyroidism are present clinically as subscapular type. In

senile cortical cataracts deeper lens fibers are affected most.

Thus, opacification of the deeper lens fibers are affected most. Common mechanism of

cataract formation. Biochemically, the lens fibers protein get irreversibly denatured and

coagulate

New Opaque Fibers DevelopmentNewly developed lens fibers that are opaque at the time of formation are seen specially

in congenital and developmental cataract. However in developmental cataracts, all

fibers are or a small bundle of finbers may be opaque and lens may continue normal

growth.

Granular Material DepositionGranular material may accumulate in the subscapular region of lens in which epithelium

is unable to produce new lens fibres such a situation can be seen in developmental and

acquired cataracts like toxic cataract, radiation cataracts, some form of senile cataract,

metabolic and complicated cataract.

It has been shown that mitotic activity of the epithelium gives rise to cellular

debris and proliferation of epithelial. These debris and proliferation of epithelial. These

debris or cells shift in the subscapular clear zone in the direction normally taken by the

growing lens fibers. This material usually accumulated at the posterior pole by the

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mitotic flow from the anterior subscapular clear zone is seen obliterated. Histological

examination confirms the cataractous changes present in this region as well.

Pigment AccumulationIn acquire senile cataract especially in nuclear cataract (senile nuclear sclerosis) typical

pigment accumulaton is seen. Excessive accumulation is seen. Excessive accumulation of

this pigment may lead to formation of deep brunescent cataract.

Lens Epitehlial OpacificationPrimary opacification of lens epithelium is seen typically with punctuate traumatic

cataract, toxic cataract and anterior subscapular cataract and in glaucoma flecks. These

changes lead to fluctuation in refractive index, light scattering amd l;oss of lens

transparency

Deposition of Extraneous Material In LensSuch type of cataract is seen typically in patients suffering from Wilson disease in whichcopper is deposited in lens capsule and lens fibers. In drugs-induced cataract like

chloropromazine cataract, the drug or its derivative is percipated in lens fibers

Biochemical Alterations In LensThe transparency of normal crystalline lens is based on small special fluctuations in the

number of protein molecules over dimension comparable to light wave length due to

high concentration of these protein molecules in the lens, none scattering light

independently of another

Cataract is explained by large molecular aggregation or by deficient fluid collectsbetween fibers. The refractive index of this fluid is much less than that of fiber

cytoplasm and light scattering occurs at this interface. Light scattering may also occur

from large protein aggregates. Limked to the cell membrane by disul fide bonds. In

nuclear cataract, light is scattered by a huge soluble protein aggregates with molecular

weight in excess of 5 diatoms. Electron microscope studies have shown that in

cataract, cytoplasm becomes granular and electron dense inclusions are compatible with

molecular aggregation and vesiculation of cytoplasm.

Every cataract lens analysed thus so for in laboratories across the world has

exhibited evidence of proteolysis (the degradation of crystalline proteins) However, the

specific protease responsible for the proteolysis of lens crystallins and the subsequent

alteration in their properties are yet to be characterised. Using specific peptide

substrates that mimic the invivo cleavage sites in crystalline, it has been demonstrated

in lens extracts the presence of proteases that may be responsible for the breakdown of

lens proteins.

The human lens expresses acylpeptide hydrolease, a member of the unique light

mole high molecular weight serine peptidase. The role of this protein in lens proteolysis

is being investigated. It has been found that cataract develops in mice that over express

this protease. The lens from these animals show the accumulation of specific peptides.

Sources and interaction of these peptides with crystalline is being investigated in order

to understand the role of these peptides in cataract formation.

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CATARACT PREVENTION AND REVERSAL

Cataracts are a loss of clarity in the tissue of the crystalline lens of the eye affecting

about 4 million Africans and about 4 million Americans. Most of this appears to be

preventable and most cataract patients are in a good position to focus on prevention

only 3.3% meet the current guideline 20/50 or worse visual acuity for recommending

cataract surgery. A healthy 91.7% even retain vision of 20/50 or better and have the

highest likelihood of success with preventive measures. Because doctors themselves lack

training in nutrition, most cataract patients are not presented with the existing research

in prevention and reversal of cataract. In fact, only 5% of eye surgeon even believe that

it is very likely that anti-cataract compound could be developed in the future.

Obviously, surgery does nothing to actually promote health or longevity.

Nutritional and other preventive measures, in contrast produce many sidebenfits,

including the potential of certain supplements incluiding vitamins c and chromium to

significantly increase life expectancy.

CIRCULATION AND MOVEMENTMaintaining flexibility in the focusing of the crystalline lens not only improves lens

nutrition and detoxification, while preventing cataract. It is also in itself strongly linked

to longevity. Aging of the lens involves crosslinking of collagen fibers resulting in

hardening and reduced fl;exibility to shift focus. This process is similar to hardening of

the arteries, and is often associated with similar changes in the joints, which like the lens

rely heavily on good regional blood circulation, since they are composed of avascular

tissue. All movement of nutrients and wastes must therefore diffuse through many cell

layers tpo maintain the metabolism of the cells. This possible movement of fluid is

greatly aided and dependent on general body movement in the case of the joints, and

general ocular motility, and especially accomodatioin, in the case of the eye lens.

TOXINS

Many toxins, including synthetic chemicals and pharmaceuticcals are known to cause

cataract. Steroid medications, even when used topically are a common trigger. Steroid,

such as prednisone, block normal metabolism of connective tissue of which the lens is

composed. anistatamines should also be avoided

Among the potentially toxic compounds observed to trigger catarcats include

naphthalene (moth balls), acetone, dinitophenol (formerly) approved for weight loss),

cresol and paradichlorobenzol (insecticide) as well as numerous chemicals andsolvents.

Many drugs can contribute to cataract such as tranquilizers, radiomimetic drugs,

myleran, myleral, nitrogen mustard, triethylene melanine (TEM), quinolone, trenimo,

endoran, methotrexate, mevacor, mimosine, corticosteroids (such as prednisolone and

cortisone), oral contraceptives, wide, mintacol, tosimilen, iodoacetic acid, treiparanol,

dibromannitola, pontocain, ergot, sulphanilamide, streptoztocine, methoxsalen. About

25% of cataract patients are in diuretics such as thiazide, which deplete vitamin c and

other water soluble to damage and discolour the lens. Among the drugs that have been

used to trest or prevent cataracts are aspirin (not recommended due to side effects).

Smoking over a pack of cigarettes a day increase cataract risk by 20.5% compared

to not smoking at all in men and increases the risk by 63% in women. Quitting smoking

without detoxification, however does not appear to completely eliminate risk. Former

smokers still show 40% elevated risk of posterior subscapular cataract in men, and

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women risk of cataract doesnt even decrease after 10 years. It is estimated that about

20% of all cataracts are caused by smoking

SUGAR

Diabetes is a common contributor to cataracts increasing risk by 3 to 4 times. High sugar

levels in the blood cause increased sugar penetration into the crystalline lens. Once

inside the lens the glucose molecules are phosphorylated (chemically bound to a

phosphoric group, making a larger molecule) and can then longer diffuse back out of the

lens even after sugar levels in the blood may have returned to normal. The increased

sugar in the lens then osmotically draws in excess water to hydrate itself, leading to

swelling and water pockets, Swelling of the lens can cause fluctuating vision, and the

microscopic water pockets disrupt the crystal lattice structure of the lens making it

cloudy and the vision hazy. Refined sugar should be avoided for prevention in any type

of cataract, while diabetics should avoid other sugars as well, and even reduce complex

carbohydrate. Lactose, found in diary products, can contribute to cataracts, destroying

glutathione and vitamin c levels in the lens. Lactose is a disaccharide comprised ofgalactose and glucose. Galactose is known to cuase cataracts, as in galactosemia. High

galactose diet cause cataract in animals and as such should either be avoided or the

quantity consumed reduced.

Monosaccharides D-glucose, D-galactose, D-xylose, and L-arabinose are known to

bhe cataractogenic and should be restricted in diet.

DRAINAGE

Drinking of adequate amount of good filtrated water or even better, microwater, helps

to maintain flows of nutrients to the lens and the drainage of metabolic wastes and

toxins from the tissue 8 to 10 glasses of water a day has been recommended.

CHAPTER FOUR

METHODS OF TREATMENT OF CATARACTS

1. Endocapsular Catarct Extraction With Intraocular Lens ImplantationIntroduction

There are many ways by which one can do an extra capsular cataract surgery.

One method is the endocapsular cataract extraction. ENdocapsular cataract

extraction is a method in which we make a letterbox type opening in the anterior

capsule. Then after expressing the nucleus and removing the cortex, the IOL is

implanted through the letter box opening. Thus the lens is between the anterior and

posterior capsule, and is thus one hundred percent in the capsular bag. Then, the

anterior capsule is removed and the wound sutured

Advantages

a. It ensures complete in the bag fixationb. There is corneal maximum protection given to IOL structures specially the

corneal endothelium and the iris

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c. In case of hypermature cataract if you had a can opener anteriorcapsullectomy, then when you just picture the anterior capsule, milky fluid

immediately