Lens diseases Wen Xu Eye 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

Cataract Symptoms:  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 cataract Description: 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 type  Four stages : (1) incipient stage (2) intumescent stage or immature stage (3) mature stage (4) hypermature stage

1. incipient stage Features: a 、 cuneiform ( 楔形 ['kjun ɪ ə,f ɔ rm]) 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 Cataract Features: 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 cataract Features: 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 cataract  Galactose 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 patients  Clinical 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  O cular: 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) 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