Lecture lens

Tuesday, May 2, 2023 anjumk38dmc@gmail.com 1

LECTURE: 1 LENS

Prof Md Anisur RahmanHead of the department (Eye)

Dhaka Medical College. Dhaka

Cross section of human crystalline lens

Human Crystalline Lens: (Applied anatomy)

The lens is a transparent, biconvex, crystalline structure placed

between iris and the vitreous in a saucer shaped depression.

Diameter is 9-10 mm

It has got 2 surfaces: the anterior surface is less convex (radius

of curvature is 10 mm) than the posterior (radius of curvature

6 mm) The two surfaces meet at the equator.

Its refractive index is 1.39 and total power is 15-16.

Human Crystalline Lens (Histopathology) Structure

1) Lens capsule: It is a thin, transparent, hyaline membrane

surrounding the lens which is thicker over the anterior than the

posterior surface. The lens capsule is thickest at pre-equator

regions and thinnest at the posterior pole.

2) Anterior epithelium: It is a single layer of cuboidal cells which

lies deep to the anterior capsule. In the equatorial region these

cells become columnar, are actively dividing and elongating to

form new lens fiber throughout the life.

Human Crystalline Lens (Histopathology) Structure

• 3) Lens fiber: The epithelial cells elongated to form lens fiber.

It form throughout the life, the older fiber resides in the centre

and form the nucleus and the peripheral called cortex.

What is cataract?

• Opacity of the human crystalline lens and its

capsule is called cataract.

Classification of cataract

A. Etiological classification

I. Congenital & developmental cataract

II. Acquired cataract

1. Senile cataract

2. Traumatic cataract

3. Complicated cataract

4. Metabolic cataract

5. Radiation cataract

6. Toxic cataract

7. Cataract associated with skin diseases

8. Cataract associated with miscellaneous syndromes

i. Dystrophic myotonic

ii. Down’s syndrome

iii. Lowe’s syndrome

B. Morphological classification: It involves the capsule & may be

1) Capsular cataract

i. Anterior capsular cataract

ii. Posterior capsular cataract

2) Subcapsular cataract: It involves the superficial part of the

cortex (just below the capsule) and includes:

Anterior subcapsular cataract & Posterior subcapsular cataract

3) Cortical cataract: It involves the major part of the cortex

4) Supranuclear cataract: It involves only the deeper part of the

cortex

5) Nuclear cataract: It involves the nucleus of the crystalline lens.

6) Polar cataract: It involves the capsule and superficial part of the

cortex in the polar region only. It may be:

Anterior polar cataract & Posterior polar cataract

Cataract maturity (This classification is only for Age related cataract)

1. Immature cataract: is one in which the lens is partially

opaque.

2. Mature cataract: when lens is completely opaque.

3. Hyper mature cataract: has a shrunken and wrinkled anterior

capsule due to leakage of water out of the lens.

4. Morgagnian cataract: is a hyper mature cataract in which

liquefaction of the cortex has allowed the nucleus to sink

inferiorly

Classification of cataract (Congenital & Development cataract)

A. Hereditary: About one third of the congenital cataract is

hereditary. Mode of inheritance is autosomal dominant

B. Maternal factor:

1) Malnutrition

2) Infection

3) Drugs ingestion

4) Radiation

Classification of cataract (Congenital & Development cataract). Aetiological

C. Fetal or Infantile factors:

i. Deficient of oxygenation: Owing to placental haemorrhage

ii. Metabolic disorder: Galactosemia, galactokinase deficiency

iii. Cataract associated with other congenital anomalies: Lowe’s

syndrome, myotonica dystrophica

iv. Birth trauma

v. Malnutrition

Classification of cataract (Congenital & Development cataract)

• D. Idiopathic

Morphological classification of congenital/Developmental Cataract

1) Congenital capsular cataract

Anterior capsular cataract

Posterior capsular cataract

2) Polar cataract

Anterior polar cataract

Posterior polar cataract

3) Nuclear cataract

4) Lamellar cataract

5) Sutural & axial cataract:

Floriform cataract

Coralliform cataract

Spear-shaped cataract

Anterior axial embryonic cataract

6) Generalized cataract

Coronary cataract

Blue dot cataract

Total congenital cataract

Congenital membranous cataract

Difference between immature & mature cataract

Immature cataract

1) Considerable vision present

2) Colour of the lens is

grayish white

3) Iris shadow present

4) Fundal glow present

Mature cataract

1) Vision is reduced to CF

2) Colour of the lens is pearly

3) Iris shadow absent

4) Fundal glow absent

How the visual acuity measure with Snellen’s chart

1) 6/60

2) 6/36

3) 6/24

4) 6/18

5) 6/12

6) 6/9

7) 6/6

Reversible blindness

1) Cataract is most common

2) Refractive error

3) Corneal opacity due to trauma, ulcer etc

4) Diabetic retinopathy

Irreversible blindness

1) Primary open angle glaucoma (POAG)

2) Age related macular degeneration (ARMD)

3) Some retinal dystrophy or degeneration

LECTURE: 2. Lens

Prof Md Anisur RahmanHead of the department (Eye)

Dhaka Medical College. Dhaka

Symptoms of cataract

1) Gradual dimness of vision

2) Sometimes mono ocular diplopia in early

Signs of Immature cataract

1) Considerable vision present

2) Colour of the lens is grayish white

3) Iris shadow present

4) Fundal glow present

Signs of Mature cataract

1) Vision is reduced to CF

2) Colour of the lens is pearly white

3) Iris shadow absent

4) Fundal glow absent

Treatment of cataract

In early stage, change of spectacle

But the surgical treatment depends upon the

patient choice and profession of the patient.

What are the surgical treatment of cataract

There are two types of cataract surgery

1) ICCE (Intracapsular cataract extraction) Now

obsolete

2) ECCE: (Extra capsular cataract extraction)

The basic difference between the two surgeries are:

• In ICCE the lens is extracted along with total capsule of the lens, so no IOL can be implanted in posterior chamber

• But in ECCE the posterior capsule of the lens is remain intact so IOL can be implanted in posterior chamber

Various types of Extracapsular Capsular Cataract Extraction

1) Extra capsular cataract extraction with posterior chamber intra ocular lens implantation (ECCE with PC IOL)

2) Small incision cataract surgery with posterior chamber intra ocular lens implantation (SICS with PC IOL)

3) Phacoemulsification with posterior chamber intra ocular lens implantation (Phaco with PC IOL)

Among these 3, SICS with PC IOL & Phaco

with PC IOL is the treatment of choice

What investigation will you do before cataract surgery?

Systemic investigations: Blood sugar: Cataract surgery will not perform if

blood sugar is above 10 two hours ABF. ECG: Not always Ocular investigation: IOP SPT Biometry

What is SPT?

SPT: Sac patency test. It is done to check whether the

lacrimal passage is open or not. If the draining

passage is blocked cataract surgery will not perform.

We have to clear the passage by doing surgery.

We have to do DCR/DCT according to patient

condition.

What is biometry?

Biometry is the procedure by which we detect the intra ocular lens power before surgery.

How to perform biometry? To calculate the IOL power which we put inside the

eye during surgery Two instruments are needed to calculate the IOL

power. Keratometer A scan ultra sonogram

Biometry

There is a formula to calculate the IOL power.P = A – {(2.5xAL) + (0.9 x K)}Here, P = Power of the IOLA = Constant (which is printed over the lens box)AL = Axial length of the globeK = Keratometer reading (Diopter power of cornea)

Biometry

• With the help of A-Scan we measure the axial

length of the globe

• We the help of kerato meter we measure the

diopter power of the cornea.

Anaesthesia used in cataract surgery

Cataract surgery usually perform with local anaesthesia

There are 2 types of block 1) Retrobulbar2) Peribulbar In some cases, such as children & non cooperative

patient we use G/A. Some surgeons prefer topical Oxybuprocaine 0.4%

in phaco surgery.

ANAESTHETIC SOLUTIONS:

Lignocaine (lidocaine) 2%: Fast onset of action and effects last for an hour.

Bupivacaine 0.5% : slow onset of action but lasts for 3-4hrs

Hyaluronidase (7.5 units/ml): Spreading agent

Retrobulbar block

The globe should be in primary gaze, looking straight

up towards the ceiling. The inferior orbital rim is

palpated through the lower eyelid.

The needle should be oriented with the bevel facing

up towards the globe. This further protects the globe

from penetration during injection.

Retrobulbar block

• The needle is then inserted through the lower eyelid,

just superior to the lateral third of the inferior orbital

rim. The temporal limbus is used as a guide, as shown

in the image below.

• The needle is advanced posteriorly parallel to the

orbital floor, which has an approximate incline of 15

degrees.

Retrobulbar block

• When the needle is approximately 50% passed (at this

point the tip of the needle will have passed the

equator of the globe), the angle of injection is shifted

medially and further superiorly to 45 degrees

allowing the needle to enter the intraconal space.

Retrobulbar block

Peribulbar block

Peribulbar block is very similar to the retrobulbar block.

Anesthetic is injected into the orbit; however, it is

administered outside of the muscle cone. Because of

this fact, this technique is lower risk than the

retrobulbar block, but achieves a lesser degree of

anesthesia and especially akinesia

Peribulbar block

• Peribulbar block should be given in upper and lower

Upper one should be given at the junction of medial

1/3 and lateral 2/3 of the superior orbital rim

Lower one should be given at the junction of lateral

1/3 and medial 2/3 of the inferior orbital rim

• (5ml should be given in each time)

Complication of blockComplication due to anaesthetic agent:• Hypersensitivity reaction• Syncope

Complication due to faulty technique• Retrobulbar hemorrhage• Perforation of the globe• Optic N injury

Pre operative preparation of cataract surgery

I. Topical antibiotic hourly from the day before surgery (except

sleeping time)

II. Sedative (night before surgery) according to patient choice.

III. Tab Acetazolamide & Tab Potassium supplement at C/M.

IV. Phenylephrine + Tropicamide eye drop 15 minute interval for

3 to 4 times before surgery to dilate the pupil.

Solve the problem

A patient 65 year old came to you for cataract surgery

(R/E) and he desires to do phaco surgery with PC

IOL, O/E you got visual acuity of R/E is 6/36. L/E is

aphakic but with glass of +10 D his visual acuity is

Now how you manage/counsel the patient?

Lecture: 317 May 2016

Prof Md Anisur RahmanHead of the department (Ophthalmology)

Dhaka Medical College, Dhaka

Steps of SICS. Step: 1Expose the eyeball

• After draping the field is ready to surgery

• Step: 1

Expose the eye ball with the help of universal

speculum & superior rectus bridle suture with 4/0 or

5/0 atraumatic silk

Steps of SICS. Step: 1Expose the eyeball

Fig: 1. Superior Rectus hold with Tooth forcep and needle of

the atraumatic silk hold with Silcock's needle holder

Fig: 2. Now the eyeball is exposed with Universal eye speculum & Superior Rectus

bridle suture

Steps of SICS. Step: 2. Construction of scleral tunnel

Give incision to the conjunctiva and exposethe sclera about 1.5 to 2 mm above the sup limbus.Give incision (crescent shaped or straight) to the sclera (half or 2/3 thickness) with crescent knife. FIG: 3

Tuesday, May 2, 2023 56

Steps of SICS. Step: 2. Construction of scleral tunnel

FIG: 4m

Then make a tunnel with

the crescent knife upto 1.5

to 2 mm of the cornea.

Then enter into A/C with

the help of keratome.

Steps of SICSStep: 3. Anterior capsulotomy

Crescent knife Keratome

Before Anterior capsulotomy stain the capsule with bluerex

Wash A/C with Ringer’s/Basal Salt Solution (BSS) Insert visco elastic substance (Methyl Cellulose) into

A/C to maintain the A/C depth.

Capsule is stained

with bluerex

FIG: 5

• There are 3 types of anterior capsulotomy1) Can opener2) CCC (Continuous Curvilinear Capsulorhexis)3) Envelope typeCapsulotomy is done with the help of Cystitome

(Cystitome is nothing but the double bent hypodermic needle)

FIG: 6. CCC FIG: 7. Can Opener

Steps of SICSStep: 4 hydrodissection & hydrodelination

• This step is not mandatory for SICS but phaco.

FIG: 8. If hydrodissection is complete there will appear a Golden

Ring Surrounded the nucleus

FIG: 8. Golden ring is seen.

Steps of SICSStep: 5 & 6. Removal of the nucleus

• Step: 5. The nucleus will be prolapse into the A/C

with the help Sinsky hook or Cystitome needle.

• Step: 6. The nucleus will be delivered with the help of

Vectis loop (many surgeons use different instrument

for nucleus delivery) FIG: 9

Steps of SICSStep: 6 Removal of the nucleus

FIG: 9 Removal of the nucleus with the help of wire loop vectis

Steps of SICSStep: 7. Cortical matter clean up

• Step: 7. When nucleus is delivered only cortical

matter is there. So cortical matter has to removed.

This step is called irrigation & aspiration.

• It is clean up with the help of Simcoe cannula. It is

also called two-way cannula

FIG: 10. Irrigation & Aspiration cannula (I & A cannula)

Steps of SICSStep: 7. How cortical matter clean up with I/A cannula?

The 2-way cannula is attached one side with 5 cc

syringe & the other end with the saline set.

When the saline is on fluid enter into the A/C.

The syringe which is attached with other end will aspirate cortical matter from

Intraocular lens made by Polymethylmeth Acrylic Refractive

index is 1.49

Intraocular lens has two parts.1) Two haptic for anchoring

2) Optical part. Lens power is in optical part

Before insertion the lens is hold with tying forcep or Mc Pherson

forcep

• After insertion of the lens the anterior chamber

washed with Ringer’s/BSS.

• Check whether A/C is normal depth or shallow. If

A/C is shallow give a bite with 10/0 monofilament

nylon.

• Lastly, apply pad for 24 hours

Lecture: 4

Prof Md Anisur RahmanHead of the department (Ophthalmology)

Dhaka Medical College, Dhaka

After cataract surgery what advice should you give to the patient?

1) Do not use water in your eyes2) Use dark black sun glass3) Do not lean forward4) Use medicine regularly5) Come after 7 days or before if any problemAbide by these rules for 4 weeks (for SICS) 2 weeks for

phaco surgery

Post operative order (oral medication)

1) Systemic antibiotic: Usually Tab Ciprofloxacin (500 mg) for 7 days

2) Analgesic (Paracetamol preferably) if pain along with anti ulcerant.

3) Tab Acetazolamide (250) and potassium supplement If IOP is raised

Post operative order (eye drop)

1) Antibiotic eye drop (Moxifloxacin/Levofloxacin): 1 drop 4 to 6 hourly for 1 month2) Steroid eye drop (Dexamethason/Prednisolone) I drop 2 hourly for 7 days 1 drop 4 hourly for 15 days Then tapper (total dose will be 6-8 weeks)3) Tropicamide 1% eye drop 8 hourly for 2 weeks

Complications of cataract surgery

• In broad heading we can divided complications of cataract surgery into 3 stages:

1) Pre operative complications: due to anaesthetic agent

2) Per operative complications: During surgery3) Post operative complications: We can divided it into

two groups: a) Early post operativeb) Late post operative

Pre operative complications

Usually it is due to anaesthetic agent and discuss

previously

Per-operative complications of SICS

Per operative: According to stages of surgeryStep: 2. Construction of scleral tunnela) Improper tunnel construction.b) Early entry into A/Cc) Anterior capsular tear during entry into A/CStep: 3. Anterior capsulotomy: In SICS usually no

complication, but in phaco there may be radial tear into capsule & phaco may be turn into SICS

Complications of SICS

• Step: 6. Removal of the nucleus: a) There is high risk, to corneal endothelial injury

which may ultimately causes bullous keratopathy. b) Iris injury & iridodialysis.c) There is chance of PCT (posterior capsular tear)d) Vitreous loss (VL)e) There is chance of nucleus drop into vitreous

• Step: 7. Cortical clean up• During cortical clean up there is chance of PCT &

Early postoperative complications

1) Wound related:i. Wound leakii. Iris prolapse2) Cornea:iii. Corneal striateiv. Corneal oedema3) Anterior chamber:v. A/C reactionvi. Hyphaemavii. TASS (Toxic Anterior Segment Syndrome)

Early postoperative complications

4) IOP related:i. Raisedii. Low5) IOL relatediii. Decenterediv. Dislocatedv. Tiltedvi. Pupil capture

6) The most devastating: Acute endophthalmitis

Late postoperative complications

1) Delayed-onset endophthalmitis following cataract

surgery develops when an organism of low virulence

such as P. acnes, becomes trapped within the capsular

bag (saccular endophthalmitis).

Late postoperative complications

2) Visually significant posterior lens capsular

opacification (PCO), also known as ‘after cataract’, is

the most common late complication of uncomplicated

cataract surgery, historically occurring

3) contraction of the anterior capsular opening

(capsulophimosis)

Lecture lens

Health & Medicine

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