Lens diseases

Wen XuEye Center, 2nd Affiliated Hospital

Zhejiang University

The most common cause of painless, progressive loss of vision today is

Cataract

Anatomy of the lens

Location

posterior to iris

anterior to vitreous Shape biconvex Structure

lens capsule

lens cortex

lens nucleus

Physiology of the lens

No vessel, nerve and transparent.

Derive nutrients from the aqueous humor

Significant refractive medium

Accommodative function

No immediate relation with adjacent tissues

Complex metabolism

Simple disorders: transparency and location change

Cataract

Definition: opacification of the lens epidemiology:

clinical cataract

corrected vision<0.5

Cataract

Mechanism:

many factors lens capsular damage

osmosis increase,loss of protective screen,metabolic disorders protein degeneration, cell apoptosis lens opacify cataract

Cataract Classification: by cause: congenital, senile(age-related), complicated,

metabolitic, drug-induced, toxic, traumatic, secondary

by age:congenital, acquired

by location: cortical, nuclear, subcapsular

by shape: dot-like, coronary, lamellar

by degree: immature, intumescent, mature, hypermature

CataractSymptoms: decreased vision: most obvious and important

decreased contrast sensitity

refractive error: myopia,astigmatism

monocular diplopia or multiple vision

glare: scattered light rays

poor color discrimination:blue spectrum

Cataract

Signs: The lens is best examined with the pupil

dilated. A magnified view of the lens can be obtained with a slit-lamp or by using the direct ophthalmoscope with a high plus (10+) setting

Cataract

Grade’s standards of nuclear hardness:

Ⅰ transparent,no nucleus,soft

Ⅱ yellow-white or yellow,soft

Ⅲ dark yellow,moderate hard

Ⅳ brown or amber, hard

Ⅴ brown or black,extremely hard

(I) Age-related cataractDescription: the most common type, most patients are beyond

their 50’s. The incidence goes up with aging. It is the

first rank of ophthalmic diseases leading to blindness

Risk factors: Many factors are involved include age, occupation,

sex, ultraviolet radiation, diabetes, hypertension,

positive family history, nutritious condition

(i) Cortical Cataract

The most common typeFour stages:

(1) incipient stage

(2) intumescent stage or immature stage

(3) mature stage

(4) hypermature stage

1. incipient stageFeatures: a 、 cuneiform( 楔形 ['kjunɪə,fɔrm]) opacity

b 、 lamellar seperate

c 、 vacuole

d 、 cracks

e 、 no vision damage

Tests: a 、 slit-lamp b 、 transillumination

2. intumescent stage or immature stage

Features: a 、 more serious opacity b 、 larger volume and more shallow anterior chamber c 、 iris shadow d 、 obvious vision decrease e 、 myopia

Tests: a 、 slit-lamp b 、 oblique illumination

Matter needs attention: angle-closure glaucoma

3. mature stage

Features: a 、 complete opacity, milky white, iris shadow

disappear

b 、 volumn and anterior chamber regain normal

c 、 vision: LP or HM before the eye

Tests: a 、 slit-lamp

b 、 flashlight

4. hypermature stage

Features: a 、 smaller volumn,wrinkled lens capsule,claybank

and fallen nucleus (Morgagnian cataract) ,superior

of anterior chamber deepens while inferior is the

opposite,ridodonesis.

b 、 laceration of lens capsule,lens luxation.

c 、 phacoanaphylactic uveitis,phacolytic glaucoma

(ii) Nuclear Cataract

Features: a 、 start earlier,generally on 40’s,slowly

progressive, not likely to be mature.

b 、 nuclear opacity: start by embryonic nucleus.

c 、 vision: no vision damage early on, myopia

Tests: slit-lamp 、 transillumination 、 oblique illumination

(iii) Subcapsular Cataract

Features: a 、 start earlier

b 、 posterior subcapsular cataract: cause

obvious vision defect early on

c 、 cupuliform( 杯状 ) opacity of posterior pole

(II) Congenital CataractFeatures: present at birth or appear shortly thereafter; unilateral or bilateral;

may be alone or associated with other ocular or systemic

congenital abnomalities

Etiology:

(1) hereditary factors(chromosome,gene)

(2) environmental factors (matrix disease) when pregnance <3 m:

virus infection; drugs,metabolic diseases

(3) undetermined causes

Classification

According to location, form and degree anterior polar cataract

posterior polar cataract

perinuclear cataract

coronary cataract

punctate cataract

total cataract

membrane cataract

nuclear cataract

Congenital cataract

Anterior polar cataract

Posterior polar cataract

Perinuclear cataract

Coronary cataract

Punctate cataract

Total cataract

Membrane cataract

Nuclear cataract

(III) complicated cataractFeatures:

ocular inflammation or degenerative disorders→

nutritious or metabolic defect → lens opacity

Common causes:

corneal ulcer, glaucoma, uveitis,retinal

detachment, retinitis pigmentosa, intraocular

tumor,high myopia, etc.

Clinical findings:

1. primary disease changes

2. cataract

Treatment:

1. treat the primary disease.

2.do the surgery after 3 m of inflammation control

(IV) Metabolic cataract

Diabetic cataractGalactose cataract: lack of enzyme

Tetany cataract: low blood calcium

Wilson’s disease (Hepatolenticular Degeneration): KF ring, sunflower-shaped

opacity,copper.

1. Diabetic cataract

Mechanism:

blood sugar↑ →sugar in the lens↑ → change

into sorbitol→plasma osmotic pressure↑

→absorb water→fibers swellen and

degenerate→lens opacity

classification: (1) real diabetic cataract

(2) age-related cataract of diabetic patientsClinical findings: (1) the first type: teenagers,bilateral,rapidly

progressive,eading to total cataract,combined

with refractive changes according to blood sugar

(2) the second type: high incidence,start earlier, fast

progressive, easy to be mature,similar with

senile cortical cataract

Treatment: (1) positively treat diabetes,control blood

sugar

(2) do the surgery if permitted

(3) positively postoperational infection and

bleeding prevention

(V) Drug-induced and toxic cataract

Corticosteroid cataract

Chlorpromazine cataract

Miotic cataract

Trinitrotoluence cataract

Metals

Trinitrotoluence cataract

(VI) Traumatic cataract

Classification: Contusive cataract

Penetrating cataract

Chemical injuries cataract

Radiation cataract

Electric cataract

Treatment: observation or surgery

(VII) Secondary cataract

Definitions: opacification of the posterior capsule due to partially

absorbed traumatic cataract or following extracapsular cataract extraction (posterior capsular opacification). It is the most common complication of cataract surgery

Clinical findings: vision decrease after cataract surgery;

Elschnig’s pearls

It is a significant problem in almost all pediatric patients unless the posterior capsule and anterior vitreous are removed at the time of surgery. Up to 30%-50% of all adult patients develop an opaque secondary membrane after cataract surgery

Treatment: neodymium:YAG capsulotomy

Treatment of cataract

There are many kinds of medicines,but none

has certain positive effect

Surgery is the chief method

Surgical treatment

Timing of the surgery: a 、 mature stage→visual acuity

b 、 consider the surgery conditions and the subjective requirements of patients

Preoperative Examination & preparation Ocular: VA,LP,color vision,anterior

segment,fundus,IOP,SLE ,EKG,VEP,ultrasonic,etc. System:BP,blood sugar,etc. Corneal curvature,the axial length of the

eye.calculate the diopter of the IOL Endothelial cell acount (specular microscopy) Wash conjunctival sac and lacrimal canal,dilate

the pupil

Way of the surgery

Couching( 针拨 ) of lens

Intracapsular cataract extraction (ICCE)

Extracapsular cataract extraction (ECCE)

Phacoemulsification (PHACO)

Laseremulsification

Intraocular lens implantation

Surgical complications

Complications during the surgery

(1)shallow or no anterior chamber

(2)intraocular tissue lesion

(3)hemorrhage

(4)posterior capsular rupture

Postoperational complication (1)hemorrhage

(2)high IOP

(3)endophthalmitis

(4)chronic uveitis

(5)posterior capsular opacification

(6)corneal astigmatism

(7)retinal phototoxicity

(8)cystoid macular edema, CME

Postoperational complications of IOL implantation

(1)pericorneal fibrous proteins exudation

(2)dislocation of IOL

(3)secondary glaucoma and decompensation of

corneal endothelium

(4)diopter inaccuracy of IOL

Refractive correction of aphakia

IOLs :Multifocal, Accommodatable

Spectacles

Contact lens

Refractive surgeries: keratophakia,

keratomileusis, epikeratophakia

Dislocated lens or ectopia lentis

Causes (1) congenital

simple dislocation; combined with lens or ocular

abnormalities; systemic syndromes (Marfan syndrome,

homocystinuria, Marchesani syndrome, Ehlers-Danlos

syndrome)

(2) traumatic

(3) spontaneous

Clinical findings (1) Partial dislocation:

the edge of the lens and the zonular fibers holding it in

place can be seen in the pupil. It is often complicated by deepen anterior chamber,iridodonesis and vitreous hernia. High myopia and monocular diplopia,or even secondary glaucoma may occur

(2) Complete dislocation:

include pupil entrapment,dislocated into anterior

chamber, dislocated into vitreous cavity,dislocated into

subconjunctiva or even extraocular

complications (1)Uveitis

(2)Secondary glaucoma

(3)Retinal detachment: the most common

(4)Corneal opacification

Treatment

(1) nonsurgical therapy: If no complications, dislocated lenses are best left

untreated. Close conservation and spectacles or contacts may have some value

(2) surgical therapy:

If uveitis or uncontrollable glaucoma occurs, lens

extraction must be done. The technique of choice is limbal or pars plana lensectomy using a motor-driven lens & vitreous cutter

Dislocated in anterior chamber

Partial dislocation

Partial dislocation