Lens and Cataract

Cataract and Refractive Surgery Subspecialty ServiceDepartment of Ophthalmology

Medicine Faculty Padjadjaran University

Topics of Study

1. CataractCauses of CataractGlobal/National distribution & population characteristics of CataractDiagnosis of Cataract. Distinction between immature, mature and hypermatureAppropriate referral of cataract patientOutline of surgical managementVisual rehabilitation of AphakiaOutline of cataract management in young age

Topics of Study

2. Congenital Abnormalities of LensEctopia Lentis (Subluxation & Dislocation)

Lenticonus

Crystalline Lens

Embryology Derived from surface Ectoderm Ectoderm invaginates and breaks as two layers

structure Basement membrane of epithelium forms the lens

capsule Posterior epithelium cells form the embryonic

nucleus Anterior epithelium continues to regenerate and

develop lens fibers

Anatomy

Lies behind the iris Concavity in the anterior face of vitreus

called the Patellar Fossa Suspended from the cilliary processes by

Zonules In young patients (<35 years) lens is

adherent to vitreus by Ligament of Weigert

Lens

Cornea

Anterior Chamber

Posterior Chamber

Sclera

Retina

Ciliary Body

Layers (from without inwards) :

Lens capsule (thinnest at posterior pole) Epithelium (missing from posterior

surface) Cortex Epinuclear Cortex Nucleus

Nucleus (from without inwards) :

Adults Adolescent Infantile Fetal (contains anterior & posterior Y-

sutures) Embryonic

Physiology

Functions :1. Refraction of light (+18 D)

2. Accomodation : ability to increase refractive power in order to focus near objects.

Optics

+18 D refraction. And in accomodation this power increases

Accomodation : contraction of ciliary muscles results in laxity of zonules, which leads to increase convexity of lens due to its inherent elasticity

Iris controls the amount of light that enters the eye by varying the size of pupil and covers the peripher of the lens thereby cutting the optical (spherical) aberrations from it

Cataract

Definition Any opacity of the lens or loss of

transparancy of the lens that causes diminution or impairment of vision

Classification

Etiological Morphological Stage of Maturity Chronological

Etiological classification

1. Senile

2. Traumatic1. Penetrating

2. Concussion (Rosette Cataract)

3. Infrared irradiation

4. Electrocution

5. Ionizing Radiation

3. Metabolic1. Diabetes (Snow Storm Cataract)2. Hypoglycaemia3. Galactosemia (Oil drop cataract)4. Galactokinase Deficiency 5. Mannosidosis6. Fabry’s Disease7. Lowe’s Syndrome8. Wilson’s Disease (Sunflower Cataract)9. Hypocalcaemia

4. Toxic1. Corticosteroids

2. Chlorpromazine

3. Miotics

4. Busulphan

5. Gold

6. Amiodarone

5. Complicated Anterior uveitis Hereditary Retinal & Vitreoretinal Disoders High Myopia Glaucomflecken Intraocular Neoplasia

6. Maternal Infection1. Rubella

2. Toxoplasmosis

3. Cytomegalovirus

7. Maternal Drug Ingestion Thalidomide Corticosteroid

8. Presenile Cataract Myotonic Dystrophy Atopic Dermatitis (Syndermatotic Cataract) GPUT & Enzyme Deficiencies

9. Syndromes with Cataract Down’s Syndrome Werner’s Syndrome Rothmund’s Syndrome Lowe’s Syndrome

10. Hereditary

11. Secondary Cataract Posterior Capsular Opacification (PCO)

Morphological Classification

1. Capsular Congenital (Anterior Polar & Posterior Polar) Acquired

2. Subcapsular Posterior subcapsular (Cupuliform) Anterior subcapsular

3. Nuclear Congenital (Discoid, etc) Senile

4. Cortical Congenital (Coronary, Coralliform, etc) Senile (Cuneiform)

5. Lamelar or Zonular

6. Sutural

7. Others Blue –Dot (Cataracta caerulea) Membranous Cataracta Pulveranta Centralis Reduplicated Cataract

Stage of Maturity

1. Immature

2. Mature

3. Intumescent

4. Hypermature

5. Morgagnian

Chronological

1. Congenital : since birth

2. Infantile : first year of life

3. Juvenile : 1 to 13 years of life

4. Presenile : 13 to 35 years of life

5. Senile

Pathogenesis

Two main pathogenetic processes are :1. Hydration :

Failure of active pump mechanism Increased leakage across posterior or

anterior capsule Increased Osmotic Pressure

2. Sclerosis

Senile Cataract

Global38 million people are blind41% because of cataract

Progression

1. Stage of Lamellar Separation Hydration

2. Stage of Incipient Cataract Early opacities appear Symptom e.g., glare, appear

3. Immature Cataract Diminution of vision Lens appears grayish white in color Iris shadow can be seen

Progression

4. Intumescent Cataract The lens imbibes lot of fluid and becomes swollen Anterior chamber becomes shallow Angle of anterior chamber may close : Phacomorphic

glaucoma

5. Mature Cataract Entire cortex becomes opaque Vision reduced to just perception of light Iris shadow is not seen Lens appears pearly white

Progression

6. Hypermature CataractThis may take any of two form : Liquefactive or Morgagnian type : milky white Sclerotic Cataract with iridodenesis Vision improves to about finger counting at 1

meter

Clinical Presentation

Symptoms1. Glare2. Image Blur3. Diurnal Variation of Vision4. Distortion (Metamorphopsia)5. Diplopia/Polyopia6. Altered Color Perception7. Black Spots8. Behavioral Changes

Clinical Presentation

Signs1. Visual Acuity : vision is diminished

proportionate to the degree of cataract (immature from 6/9 to finger counting close to face; mature perception of light or hand movements)

2. Leukocoria : white pupil3. Iris shadow in immature cataract4. Distant Direct Ophthalmoscopy (DDO) : red

reflexes depends on degree of cataract

Differentiating Various Stages of Cataract

Features Immature Mature Hypermature

Vision 6/9 - FC HM - PL HM – FC

Anterior Chamber

Normal (shadow in intumescent)

Normal (shallow in intumescent)

Normal to deep

Color of Lens Grayish white Pearly white Milky white(with browm crescent of nucleus) or chalky white

Iris shadow Seen Not seen Not seen

Distant Direct Ophthalmoscopy

Black patches againts red glow

No red glow seen

No red glow seen

Complication of Cataract

1. Lens Induced Glaucoma1. Phacomorphic Galucoma

2. Phacolytic Glaucoma

3. Phacotopic Glaucoma

2. Lens Induced Uveitis

3. Subluxation or Dislocation of Lens

Investigation1. Visual Acuity2. Pupillary Reflexes3. Intraocular Pressure4. Fundus Examination5. Blood Pressure6. General Investigation7. Macular Function Test8. Ultrasonography (USG B-Scan)9. Intraocular Lens Power Calculation

Biometry

Indications for Cataract Surgery1. Optical indications2. Medical indication

Hypermature cataract Lens induced glaucoma Lens induced uveitis Dislocated/subluxated lens Intra-lenticular foreign body Diabetic Retinopathy to give Laser

Photocoagulation Retinal Detachment

3. Cosmetic indication

Surgery for Cataract

Choice of Operation :1. Extra-capsular cataract extraction with

Posterior Chamber Lens Implantation (ECCE with PCL)

2. Intra-capsular cataract extraction (ICCE)3. Pars plana lensectomy4. Phacoemulsification with Foldable Intra-

ocular Lens (IOL)

Intra-ocular lens (IOL) types :1. Posterior chamber lens (PCL)

2. Anterior chamber lens (ACL)

Principles of Various Techniques

1. ECCE The nucles and the cortex is removed out of

the capsule leaving behind intact posterior capsule, peripheral part of the anterior capsule and the zonules

2. ICCE The lens is removed in toto

3. Pars Plana Lensectomy A special techniques used in very young

children The lens and anterior part of vitreous is

nibled out using an instrument called Vitrectomy Probe or Vitreous irrigation Suction Cutting (VISC)

4. Phacoemulsification It is essentially an advancement in the

methode of doing ECCE The nucleus is converted into pulp or

emulsified using high frequency (40.000 MHz) sound waves and then sucked out of the eye through a small (3.2) incision

A special foldable IOL is then inserted Is the choice of the operation for cataract

ECCE vs. ICCE

ECCE ICCELens removal Nucleus removed out

of the capsule and cortex sucked out

Lens removed as single piece within its capsule

Posterior capsule & zonules

Intact Removed

Incision Smaller (8 mm) Larger (10 mm)

Peripheral iridectomy Not performed Required to avoid pupillary block glaucoma

Sophisticated equipment

Required Not required

Time taken More Less

ECCE vs. ICCE

ECCE ICCEIOL Implantation Posterior chamber Anterior chamber

Expertise required Difficult technique Easier to learn

Cost More Less

Complications which are increased

Posterior Capsular Opacification (PCO)

1. Vitreous prolapse & loss

2. CME

3. Endophthalmitis

4. Aphakic Glaucoma

5. Fibrous & endothelial ingrowth

6. Neovasc. Glaucoma in PDR

ECCE vs. ICCEECCE ICCE

Complications which are decreased

All the complications mentioned for ICCE

PCO

Indications A routine procedure for all forms of cataract (except where contra-indicated

1. Dislocated Lens

2. Subluxated Lens (>1/3 zonules broken)

3. Chronic Lens Induced Uveitis

4. Hypermature Shrunken Cataract

5. Intraocular foreign body

Contraindications 1. Dislocated lens

2. Subluxated lens (>1/3 zonules broken)

Young patient (<35 years)

Preoperative Preparation

1. Patient preferably admitted to the hospital on previous evening (however, surgery can also be done on OPD basis)

2. Informed consent is taken3. The eye-lashes are trimmed carefully4. Antibiotic drops are instilled every 6 hourly5. Pupils are dillated6. Other medications e.g., antiglaucoma drugs,

antihypertensives, etc

Anesthesia

1. Topical anesthesia

2. Retrobulbar anesthesia

3. Peribulbar anesthesia

4. Subtenon anesthesia

5. General anesthesia

Postoperative Care

1. Eye is cleaned routinely2. The eye is examined :

Visual acuity Apposisition of the wound Corneal clarity Anterior chamber depth Pupil IOL Posterior capsule Intra-ocular pressure (IOP)

3. Topical antibiotic-steroid eye drops every 4-6 hourly (4-6 weeks)

Complication of Cataract Surgery

These can be grouped as :

1. Intraoperative

2. Postoperative : Early Late

Intraoperative Complications

1. Damage to corneal endothelium

2. Rupture of posterior capsule

3. Vitreous prolapse and loss

4. Hyphaema

5. Expulsive hemmorrhage

6. Dislocation of nucleus into vitreous

Posoperative Complications

Early1. Corneal edema2. Wound leak3. Iris prolapse4. Shallow or flat anterior chamber5. Hyphaema6. Hypotony7. Glaucoma8. Decentered or displaced IOL9. Endophthalmitis

Late1. Posterior Capsular Opacification

(PCO)

2. Cystoid Macular Edema (CME)

3. Vitreous touch syndrome

4. UGH syndrome

5. Bullous Keratopathy

6. Glaucoma

Visual Rehabilitation After Cataract Surgery (Aphakia)

1. Absolute high hypermetropia

2. Astigmatism

3. Loss of accomodation

4. Altered Color Perception

5. More of UV rays reach the retina

Rehabilitation

Three methods are mainly used to

tackle the problems of aphakia :

1. Intraocular Lens (IOL)

2. Spectacles

3. Contact Lens

Aphakic Spectcles

Physical and Optical Problems :1. The glasses are heavy and great

physical discomfort2. Magnification : diplopia3. Roving Ring Scotoma4. Jack in the box Phenomenon5. Pin Cushion Effect6. Spherical Aberations7. Chromatic Aberation

Pediatric Cataract

Main problems

1. Visual Assesment

2. Vision Deprivation Amblyopia

3. Postoperative Inflammation and Fibrosis

4. PCO

5. IOL Power Calculation

Dislocation of Lens

Congenital 1. Familial2. Ectopia lentis3. Marfan’ Syndrome4. Weil Marchesani Syndrome5. Homocystinuria6. Hyperlisinemia7. Aniridia

Acquired1. Hypermature cataract

2. Trauma

3. Chronic uveitis

4. Intraocular tumor

5. High myopia

6. Buphthalmos

Treatment

1. Spectacles

2. ECCE : only 1/3 zonules are broken

3. ICCE : more than 1/3 zonules are broken

4. Pars Plana Surgery

Miscellaneous Condition of Lens

1. Lenticonus

2. Lens Coloboma

3. PCO