LENS

LENS DEVELOPMENT

3rd week→ Ectoderm overlying the optic vesicle thickens to form – LENS PLACODE
Cells of len placode arc posteriorly to form a concave depression- LENS PIT
Margins of the lens pit fuse to form- LENS VESICLE
Cells of the post wall elongate to form the lens fibres
Ant wall remains as a single layer of cubical epith & the vesicular lumen gradually obliterates.This is the EMBRYONIC NUCLEUS [ 4th wk]
5th wk→ Cells of the lens produce a true BM i.e –LENS CAPSULE
2nd mo→ Lens fib terminate into ‘Y’ shaped sutures- Upright-ant surface & inverted – post surf
3rd-8th mo – FETAL NUCLEUS
Last wk of fetal life to puberty- INFANTILE NUCLEUS
After puberty→ ADULT NUCLEUS

LENS CRYSTALLINES [D-O4]

Lens proteins- 2parts

Albuminoid-insoluble-present in nucleus
Crystallines

-soluble
-present in cortex
-make up bulk of refractive fibres of lens,therefore considered structural proteins
-Synthesis occurs on the surface & equator of lens
- 3 components-

1} alpha- 31.7%-highest mol wt
2} Beta -53.4 %
3} Gamma- 1.5 %

Cataract means-WATERFALL

STAGES OF CORTICAL CATARACT-

Lamellar separation
Incipient stg [ISC]
Intumescent stg [ISC]
Mature
Hypermature

morgagnian type
Sclerotic type

INCIDENCE of cataract blindness-80.7%

AFTER-CATARACT-case

DEF-

Membranous white opacity formed by the remnants of anterior & posterior capsule after cat extrn

Also k/as posterior capsular opacification.0r secondary cataract

MECH OF FORM-

In immature cat , some soft cortex sticks to the capsule & is diff to remove.
This gets entrapped by adhesion of ant capsule remnants to post cap.
The cuboidal cells lining the ant capsule continue to form new lens fibres which are opaque.

TYPES OF PCO-

Nmlly lens epith cells are present on anterior surf,equatorial region & equatorial bow

Fibrosis type-

-Lens epith cells are present behind the anterior lens capsule.

-They do not undergo mitosis

-When stim they proliferate & undergo fibrous metaplasia

Pearl type-

Lens epith cells are present in the equator
Undergo active mitosis
Form new lens fibres

FACTORS INFLUENCING PCO-

1.Heparin reduces PCO

2.Epith cells shud be removed by polishing the capsule

3. CCC prevents PCO

4. PCO Occurs more frequently in children b/o greater proliferative potential of epith cells in younger age grp.Posterior capsulorhexis prevents PCO

5. Uveitis→ more inflammation→ more PCO

6. IOL design- If part of IOL is snugly apposed to PC,chances of PCO are less.Hence posterior convex or biconvex lenses are preferred.

- Post angulation of IOL optics will enhance optic capsule contact.

-In the bag IOLs stretch the bag & this stretched capsule remains in apposition with the posterior surface of IOL

-PMMA is better than polypropylene as it has better memory & on insertion into the bag ,they come to their original shape & stretch the bag

SOEMMERRING’S RING-

Ring behind the iris formed by lens fib enclosed bet the two layers of lens capsule.

Causes-

Incomplete cortex removal
Trauma

ELSCHING’S PEARL-

The subcapsular cuboidal cells proliferate & instead of forming lens fibres form large balloon like cells (Wedl cells) which fill the pupillary aperture.

Meticulous hydrodissection & cortical clean-up prevents PCO

TREATMENT-

A] Nd:YAG Capsulotomy-

-Distant Direct Ophthalmoscopy→ tells abt media opacity

-Direct O’scopy → to assess severity of PCO

-to rule out CME

-Procedure-

* Apraclonidine E/D one hour prior & on completion

* Power- 1mJ/ pulse

* A series of punctures are applied in a cruciate pattern,the first puncture aimed at the visual axis

* A 3mm opening is adequate

-Complications-

1. IOL pitting

2.CME- less common when c’tomy is delayed for 6mo or more

3. Rheg RD

4.rise in IOP

5.Post IOL subluxation / dislocation

6.Chr endoph- d/t release of sequestered org into the vitreous

Q. VIVA- MC type of congenital cataract-

A – Lamellar cataract

Q- Advantages of capsulorrhexis over capsulotomy-

A- 1. Stronger edge

2. Implant can be held more securely

3. Better centration

SUBLUXATED LENS [D-04,j-07]-case-

Instrum-wire vectis

CAUSES-

1.Trauma

2. Hereditary-

Marfan’s sy
Ehler Danlos syn
Weil Marchesani sy
Crouzon sy
Aniridia

Congenital-

Buphthalmos
ectopia lentis

Metabolic-

Homocystinuria
Hyperlysinemia
Sulphite oxidase def

High myopia
HMSC
Acqd syphilis
PXF

SYMPTOMS-

-DOV

-Monocular diplopia

SIGNS-

Decentered lens
Iridodonesis
Phacodonesis
Marked astigmatism
Asymmetry of AC depth

COMPLICATIONS-

Astigmatism
Monocular diplopia
Uveitis
Pupillary block glaucoma

T/T- [J-07]

1] FOR SUBLUXATED CLEAR CRYSTALLINE LENS-

-Spec correction thru the aphakic or phakic part ,whichever part is more

- Miotics & mydriatics

2] FOR CATARACTOUS LENS-

For small zonular tear→

ECCE + PCIOL + CAPSULAR TENSION RING

If the zonular tear is more→

ICCE with vectis is the t/t of choice.This is followed by anterior vitrectomy + /- ACIOL.

Sometimes, a scleral fixated IOL may be considered when the other eye is normal or pseudophakic

Routes for approach-

1. Limbal approach

2. Pars plana approach

3] FOR ANTERIOR DISLOCATION-

Remove as early as possible\

Immediate ICCE + Vitrectomy + /- AC IOL

4] FOR POSTERIOR DISLOCATION-

Fixed to retina- Leave it

Only aphakic glass is prescribed

Mobile→ It can cause→ * glaucoma

* inflammation

* obstruct visual axis

Go for surgical removal by pars plana approach

First do a complete vitrectomy

Then lens removal by

1] Limbal route-with MVR blade

Or – endocryo

Or – PFCL→ float the lens away from the retina

& then remove

2]Pars plana route-

Lens is floated with PFCL in midvitreous→ crushed with endoilluminator & V’tomy probe→ removed with V probe or phacofragmentome.This method is better as damage to retina is less as the lens is removed in midvit &AC is not opened

A scleral fixated IOL can be implanted.

C/I of scleral fixated IOL-

-Inflam

iritis

EXPULSIVE H’AGE-viva

SIGNS

Shallow AC
Iris prolapse
Vitreous extrusion
Dark mass behind the pupil
Loss of red reflex
Extrusion of IO contents

LOCAL ANAESTHESIA

Topical
Retrobulbar
Peribulbar
Facial

AGENTS-l

Inj Lignocaine ( 2%)

Onset of action- 5-10min
DOA-45min-2hrs

2.Inj bupivacaine (0.5-0.75 %)

-onset- 15-20 min

-DOA- 5-8 hrs

Adjuvants-

Inj Adrenaline (1 in 100,000)

Vasoconstriction→ reduces systemic absorption of anaes agent
Reduces blding
Prolongs DOA
C/I- HT, IHD

Inj Hyaluronidase ( 75-150 units/10 ml)

-Enhances diffusion of anaes agent

FACIAL BLOCK-

Block Facial N or its zygomatic br→ paralyze the orbicularis oculi→prevents closure & squeezing of lids

1.O’BRIEN’S TECH-

At the neck of mandible just in front of tragus

2. VAN LINT’S TECH-

1cm below & behind the lateral canthus→ along superolateral orb margin→ along inferolat orb margin

ATKINSON’S TECH-

Post to a vertical line drawn from the lat orb margin→along the zygomatic arch→ towards the top of the ear.

4.NADBATH ELLIS TECH-

Bet the anterosuperior border of mastoid process & ramus of mandible

RETROBULBAR BLOCK-

AIM-

To block the III n before it enters the 4 recti in the post intraconal space.

EYE POS-

Primary gaze bcos the ON is directed away from the path of needle

INJ SITE

Junctn of medial 2/3rd & lateral 1/3rd of inferior orbital margin in the muscle cone

EFFECTS-

anaesthesia of iris
Akinesia of EOM [ except SO]
Mydriasis
Hypotony
Proptosis
Decrease oculo-cardiac reflex

COMPLICATIONS-

Retrobulbar h’age
Ocular perforation
Subarachnoid / intradural h’age→ brainstem anaesthesia
Respiratory arrest
Optic N contusion & atrophy
Retinal vas occlusion
Fall in V/A
Hypotony
Ms – Ptosis, entropion & diplopia

ADVANTAGES-

Excellent akinesia & anaesthesia
quick onset of block
Low vol of anaesthetic- lower intraorbital tension

-Less chemosis

DISADVANTAGE-

Higher complication rate

PERIBULBAR BLOCK-

AIM-

To instill LA outside the ms cone & avoid proximity to optic N.

EYE POS-

Primary gaze

INJ SITE-

Junctn of med 2/3rd & lat 1/3rd of lower orbital margin outside the ms cone

ADVANTAGES-

Less- RBH

Globe perforation
ON damage

Less painful
No need of additional facial block

DISADVANTAGES-

Longer time to achieve akinesia
Chemosis & lid edema
Ptosis

Q Causes of posterior subcapsular cataract-

A –1.Steroids

2.DM

3. chr inflame

4. RP

5. Trauma

Q.what are the problems with PSC?

A –Diff in near vision

- night glare

Q what are the complications of a morgagnian cataract ?

A – Anterior seg inflamn

_ Glaucoma [ Liquefied cortex escapes & clogs the TM]

ENDOPHTHALMITIS

DEF-

Inflammation of inner layers of the eye resulting from intraocular colonization of infectious agents & manifesting as exudation in the vitreous cavity.

ORGANISMS-

A] EXOGENOUS-

When infectious agents reach the vit cavity across an opening in the ocular coat.

1. Acute postoper- [1-7 days after surgery ]-

Staph epidermidis [MC]

Staph aureus

Strepto

Gm –ve- Pseudomonas

-Proteus

-kleb

-H. inf

-E. coli

-Bacillus

-Enterobacteriaceae

Anaerobes

2. Delayed onset [wks –mo/yrs after surg]

-Fungi-

* Aspergillus

* Fusarium

* Candida

* Cephalosporium

* Penicillium

-Bacteria-

* Propionibacterium acne[equatorial capsular plaque-classic finding]

* S. epider

* Corynebacterium

* Actinomyces

3. Post-Traumatic-

Bacillus

Staph epider

Strepto

Fusarium

Mixed flora are common

B] ENDOGENOUS –

When infectious agents reach the vit by haematogenous dissemination

* Strep

* Staph aureus

* Bacillus cereus

* N. meningitides

* H.inf

* Mucor

* Candida

POST –SURGICAL ENDO

Surgical factors-

1. Type of IOL-

-Bacteria adhere strongly to hydrophobic IOL & hydrophilic - surf repels them

-Silicone attracts bact

-Fluorine is a superior coating than heparin for PMMA

2.PC tear

3. Aqueous is antibact whereas vit is a good culture medium

4. Temporal incisions carry more risk [lack of protection from lid & conj]

Propionibacterium acne-

-White capsular plaque composed of sequestered collection of org inside the capsular bag.

-Precipitated by yag c’tomy which releases sequestered org from PC into vit

- Rx- Total capsulectomy + IOL explantation to eradicate colonies of P. acnes

-Antibiotic of choice- Vancomycin

BLEB RELATED ENDO-

-High risk with- Thin walled blebs

-use of antimetab

-inferior limbus blebs

-It is imp to diff blebitis from end-in the former infection is confined to the bleb & AC & prognosis is good

-Org- Strepto & H influenzea [ penetrate intact conj easily]

Severity of end is graded as Severe & not severe

SEVERE-

Inaccurate PR
RAPD
No fundal glow
Limbal ring abscess
No response to intravitreal antibiotics

POST-Sx FUNGAL ENDOPHTHALMITIS-

C/F- Blurring of vision

-Floaters

-AC- Fixed hypopyon & a fibrinous mesh like exudation

-Vitreous- Snow-balls & fluffy opacities

Imp considerations-

- Prior to an intravitreal injection,any infected suture or suture abscess should be removed.

-pay attention to wound integrity & status of lens which decides the site of entry.In aphakia with a broken vitreous phas, a translimbal route may be employed

-If there is vitreous herniation or incarceration in the wound,then a limited anterior V’tomy + wound revision should be planned along IV inj

-Also rule out rise in IOP & pre-existing RD or choroidal det

STERILE ENDO-

Results from-

1.Retained lens matter

2.Chem. Sterilization

3.Toxicity of residual monomers on PMMA IOL

4.Mechanical irritation of iris & CB by the lens

AETIOLOGY-

A] INFECTIVE-

1) EXOGENOUS-3 times MC

* Penetrating inj

* IO surgery

* Wound leak / bleb inf

* Perforating cor ulcer

2)ENDOGENOUS-

Septic emboli from –Endocarditis

-Otitis media

-Meningitis

Seen mainly in immunocompromised subjects-METASTATIC ENDOPHTHALMITIS-occurs d/t hematogenous spread of infective org to the eye.

Predisposing factors-

1. prolonged antibiotic

2. abdominal Sx

3. Prolonged hyperalimentation

4. Indwelling intravenous catheters

5. Hematological malignancies

6. Pulmonary & renal dis

7.Uncontrolled DM

8. IV drug abusers

9. AIDS

10. Neutropenia

11.Prolonged steroid & immunosuppressant for organ transplant & bone marrow transplant

12. Contaminated IV dextrose infusion

Causative agents-

* Candida albicans-MC

* Aspergillus (A.fumigatus & A.flavus)

* Histoplasmosis

* Coccidiodomicosis

* Cryptococcus

* Fusarium

* Blastomyces

* Sporothrix

* Mucormycosis

C/F-Pain,redness,floaters,discharge & DOV

Candidiasis-

-Lesions are present in the retinal periphery and hence extensive disease may present without causing much symptoms

-Focal chorioretinitis

-‘Puff balls’ in vitreous

-Cotton –white lesion ‘string of pearl’ due to extension of lesion into the vit

Aspergillosis-

Lesions involve the macula & are highly symptomatic

-Chorioretinal lesions are more confluent with indistinct margins

D/D-

-Bacterial endogen endo

-ARN

-PORN

-CMV Retinitis

-Ruptured cysticercosis

-Toxoplasmosis

Rx-

-Yeast like- oral fluconazole

-Aspergillus-Itraconazole

-New drug- Voriconazole-oral,intravenous-200mg/d or intravenous

Prognosis-

Aspergillus has poor outcome as compared to candida

B] TOXIC [STERILE]-

* Retained IOFB [copper]

* Foll IOL implant

* Toxic reac to chem adherent to instruments, foll chem sterilization

* Necrosis of IO tum

* Phacoanaphylactic uveitis

C/F-

-Cardinal features-Pain

-Lid edema

-DOV

-Systemic features- Fever

-Headache

-Vomiting

-Signs- V/A- Less than anticipated & may be HM or only PL

-Lid edema

-Intense ciliary & conjunctival congestion [ VIVA]

-Chemosis

- Cornea-varies from clear cor to Cloudy & edematous cor

-Ring abscess

-Cor melting

-Suture abscess

-Wound dehiscence

-AC- KPS & Flare

-Frankly fibrinous

-hypopyon-most cardinal sign

-Iris- pattern lost,boggy & muddy

-Posterior synechiae

- Pupillary light reaction- absent or sluggish

-Pupillary membrane

-Vitreous- Purulent

-Yellow reflex

-IOP –usually on lower side

Clarity of media is graded by EVS as-

Grade 1. More than 20/4o [6/12] view of retina

Second order retinal Vs visible
Some Vs visible but not 2nd order
no retinal Vs visible
No red reflex

COMPLICATIONS-

Panophthalmitis- Inv of Tenon’s capsule→ painful & limited OM

-Proptosis

-Orbital cellulites

-Cavernous sinus thrombosis

-meningitis

-Brain abscess

- Sev cases → Cyclitic membrane→ destruction of ciliary processes→ fall in IOP→ Globe shrinkage

-Pus bursts thru the wall of the globe behind the limbus→Pain subsides

- Not likely to set up sympathetic ophthalmitis

INVESTIGATIONS

Lid margin & conj swab
AC Tap
Vitreous Tap
USG
Complete blood count

1. AC TAP-

-Topical anaesthesia

-With a 30 gauge needle [26G if thick pus] 0.1ml Aq is aspirated

2. VITREOUS TAP-

-26 G needle is inserted thru the pars plana [3mm post to limbus-pseudophakia /aphakia & 4mm in phakic eyes]

-Tip of the needle shud be visible thru the pupil

-0.2 ml of vit is aspirated

3.VITREOUS BIOPSY-

Adv-1. Enables an adequate vol of sample

2. Prevents vitreous traction by cutting the strands rather than pulling on them

Procedure-.

* The suction line on the vitreous cutter is replaced by a shorter tubing with tuberculin syringe at one end to enable suction

* Vitreous cutter is placed in the anterior vit & cutting is actuated.

* Simultaneously the piston is withdrawn to induce suction.

* 0.2 – 0.3 ml of sample is aspirated

AC & vitreous samples are directly inoculated onto-

Blood agar plate

2 Chocolate agar plate [37 deg C in CO2]

3.Sabouroid’s med [25deg C]

Thioglycolate-anaerobes [37 deg C]
Brain heart infusion broth

Transferred to the lab for microbio study.

But if immediate processing facilities are not available→innoculate the specimen into transport med such as-Robertson’s cooked meat broth which can be stored at room temp & transfer to the lab

Microbiological study-

1.Gram’s stain

2 Giemsa’s stain

3 KOH

4.Calcoflour stain [if fungus is strongly suspected]

Laboratory confirmed growth is defined as-

1] Atleast semiconfluent growth on solid media

2] Any growth on more than or equal to 2 media

3] Growth on one media + positive gram stain

OBJECTIVES IN ENDO Rx

PRIMARY-

Control /eradicate infection
Manage complications
restoration of vision

SECONDARY-

Symptomatic relief
prevent panophthalmitis
maintain globe integrity

T/T-

A] TOPICAL ANTIBIOTICS-

According to EVS Vancomycin ( 50mg/ml) & Amikacin ( 20mg/ml) are recommended

Fortified cefazolin [5%] OR Vancomycin [5%]

Gentamycin[1.3%] OR Amikacin [1.3%]

See cor for fortified drug prep

B] CYCLOPLEGIC-

Atropine E/O 1 % TDS

C] INTRAVITREAL ANTIBIOTICS-

- Injected after taking a 0.2-0.3 ml vit aspirate for preparing smears & cultures

AMIKACIN [0.4 mg /0.1ml]

[Amikacin covers gm –ve]

CEFTRIAXONE OR VANCOMYCIN

[2mg / 0.1 ml] [1mg / 0.1ml]

+ [vanco covers gm +ve]

DEXAMETHASONE [0.4 mg /0.1ml]- optional

ADV-

Reduce tissue damage by inhibiting arachidonic acid metabolism

DISADV-

Reduce the ability of eye to sterilize the inoculum of microorganisms

Gentamicin should be avoided as it causes macular infarction & shows high drug resistance

If fungus suspected- IV AMPHOTERICIN-B [5μg /0.1ml] without steroids

INTRAVITREAL DRUG PREPARATION-spot

1. VANCOMYCIN-

* 1000µg [1mg] in 0.1ml

-500mg vanco + 10ml SW→50mg in 1ml & hence 10mg in 0.2ml

-withdraw 0.2ml & dilute with 0.8ml SW

-This will give a strength of 10mg in 1ml & hence 1mg in 0.1ml

In simple way-

500 mg - 10ml

50mg - 1ml

10mg - 0.2ml

0.8ml

10mg - 1ml

1mg - 0.1ml

CEFTAZIDIME-2.25mg in 0.1ml

500mg Cef - 2ml SW

250mg [active ingredient-225mg] -1ml

25 mg [22.5mg] - 0.1ml

0.1ml + 0.9ml = 25 mg [22.5mg] in 1ml

Hence 2.25mg in 0.1ml

CEFAZOLIN-2.25mg in 0.1ml

Same as above

AMIKACIN-400µg [ or0. 4mg ] in 0.1ml

-Available as 100mg in 2ml vial

-50mg - 1 ml

10mg - 0.2 mlSW

2.3ml SW

This gives 10 mg in 2.5 ml

-Hence 400µg in 0.1ml

GENTAMICIN-200 µg [ or 0.2 mg ] in 0.1ml

-Available as 80 mg in 2ml vial

40mg in 1ml

4mg in 0.1mlSW

1.9ml SW

This gives 4mg in 2ml

2mg in 1ml

0.2mg in 0.1ml

AMPHOTERICIN-B-5µg in 0.1ml

-50mg Ampho + 10ml of 5 % dextrose

-5mg in 1ml

-500µg in 0.1ml

9.9ml

This gives 500µg in 10ml

-50µg in 1ml

-5µg in 0.1ml

D] SUBCONJUNCTIVAL –

* Amikacin-25mg/ 0.5 ml

* Vancomycin -25mg /0.5ml

* Ceftriaxone 100mg / 0.5ml

* Dexamethasone 6mg/ 0.25ml

COMPLICATIONS OF INTRAVITREAL-

1. Elevated IOP

2. Intraocular h’age

3. Hyphaema

4. Drug induced retinal toxicity

5. RD

E] Topical cycloplegics-atropine 1% E/O TDS

-Relieve ciliary spasm

-prevent synehiae formation

-enable better clinical evaluation

F] Topical Timolol 0.5% BD

Oral acetazolamide 250 mg qid for rise in IOP

G] PARS PLANA VITRECTOMY- immediately

-If V/A PL + or worse

No response to IV antibiotics within 48 hrs

ADVANTAGES OF PPV-

Decrease the toxic & inflammatory load
Provide adequate undiluted specimen for culture studies
Increase antibiotic concentration
Remove media opacity
Rapid visual recovery

CARDINAL PRINCIPLES OF PPV-

Use maximal cutting rate
Minimal suction
Do not attempt to induce a PVD if it is not already present

F] Eye cannot be saved or NO PL→ EVISCERATION with Frill excision [Collar of sclera is left around ON to prevent spread of inf up the ON sheath giving rise to meningitis]

- - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - -

PARSONS-

* Lens diam- 8.8-9.2mm

* Weight at birth-65mg & at 80 yrs-258mg

* Thickest at the anterior pre-equatorial region

* Thinnest at the posterior pole

* 3 Factors occur in cataract formn-

Hydration
Denaturation of lens proteins
Slow sclerosis

Soft cataract- Wen hydration is predominant

Hard cataract-Wen slow sclerosis is predominant

* Snowflake cat- Juvenile DM, Down’s syn

* Christmas tree cat- Dystrophia myotonica

* Shield cat- Atopic dermatitis

* Flower / rosette cat – trauma

* Sunflower cat- Copper toxicity

Drugs causing cat-

1.Steroids

2. Anticholinesterases

3. Chlorpromazine

4.Busulphan

5.Chloroquine

6.Amiodarone

Copper, iron gold

SECOND SIGHT-

In nuclear cat, Change in refractive index of of lens causes index myopia thus improving near vision

COMPLICATED CATARACT-[j-02]

Inflam-

-Iridocyclitis

- pars planitis

-Choroiditis

- Endophthalm

-Hypopyon CU

2. Deg-

-RP

-Myopic chorioret deg

3. RD

4. glaucoma

5. IO tum- RB

- Malignant melanoma

Characterised by- Breadcrumb appearance & polychromatic luster

PAEDIATRIC CATARACT-case

Read from notes

IOL IN CHILDREN

IDEAL LENS-

Min impact on ocular tiss
Loops shud not retain elasticity
Loops shud not compress the angle or sulcus
Lens shud not move in the eye wen rubbed vigorously

TIMING OF SURGERY-

A] BILATERAL - DENSE→ 6 wks of age or before 3mo

-PARTIAL→monitor lens opacity & visual function & intervene later

Sx on the two eyes should be separated by 2weeks for childn < 2yrs & 1mo for childn > 2yrs

B] UNILATERAL-DENSE→urgent surg within days f/b aggressive t/t.If detected after 16 wks of age then surg is inadvisable as amblyopia is refractory.

-PARTIAL→ observe

-Pupillary dilatation

-part-time contralateral occlusion

What surgery you will do?

Child < 3 years→ Cataract extraction + Ant v’tomy + PPC

Child > 3 years→ Cat extraction + Ant v’tomy + PPC + PCIOL

SELECTION OF IOL-

Best material- PMMA & foldable acrylic lenses

Ideal dia-10.5-12mm

IOL POWER-< 2yrs-do biometry & undercorrect by 20 % [as myopic shift occurs later]

AXIAL LENGTH	IOL POWER
17mm	25D
18mm	24D
19mm	23D
20mm	21D
21mm	19D

2-8 yrs-Do biometry & undercorrect by 10 %

SURGERY-

INDICATIONS-

1.Visually significant cataract [ > 3mm]

2.Dense nuc cat

3.cat obstructing fundal view

.4.Cat preventing refraction

5.C/L cat removed

6.Strabismus

7.Nystagmus

IOL IMPLANTATION-

A] CAPSULAR / IN THE BAG FIXATION-

* more physiological but diff

* 2-8 yr old

* Sequesters the implant away from the vascularised tiss

* Cap fixation has been strongly recommended

B] CILIARY SULCUS FIXATION-

*Neonates & infants

* ADV-Easier to insert

-Easy to remove later if exchange needed

* DISADV- Pupillary capture & IOL decentration

PROCEDURE-

-Cataract aspiration + Prim post capsulectomy + Ant vitrectomy

-Ped cat are soft.So phaco Power is rarely needed

-Lens cortex & nucleus are easily aspirated with an irrigation/aspiration or v’tomy handpiece

-PPC prevents PCO

COMPLICATIONS

A] INTRAOPER-

1.AC collapse

2. Iris prolapse

3.Pupil constricts on inj to iris

B] IMMED PO

1.Ant uveitis

2.rise inIOP

3.Iris incarceration

4. Endoph

C] LATE-

1. IOL dislocation

2.Chr iritis

3.Glauc

4. RD

SECONDARY IOL-

When great myopic shift occurs
When myopic shift more than 7D compared to fellow eye occurs

VISCOELASTICS-spot

PHYSICAL PROPERTIES-

Optical-transparent

-RI similar to aq

-colour slightly diff from aq

2. Lower surface tension & lower contact angle

Therefore better ability to coat

2.Viscosity

3.Elasticity-Should regain its shape after being forced out thru a narrow & fine needle

4. Slow velocity

5. Cohesiveness

6. Protective to endo,separate tiss & maintain the eye shape.

CHEMICAL PROPERTIES

Inert
Iso-osmotic
Free of particulate matter
Non-pyrogenic
Non-antigenic
Non-toxic
Non-allergic
Resorbed without inflamn
Hydrophyllic

10.Dilutable

11. No interference with wound healing

SODIUM HYALURONATE-

1% Healon

Source- Rooster comb

-Umbilical cord

-strepto culture

Adv-

non-inflam
Non-allergic
Non-carcinogenic
Does not support bact growth
Can be stored at room temp for 1mo
PO rise inIOP less

Disadv-

autoclave not possible
rise in IOP
poor coatability
crystalline deposits on IOL

CHONDROITIN SULPHATE- Viscoat

20% & 50%

Source- Shark cartilage

-Genetic engineering

Adv- better viscosity

Disadv-

Large bore cannula reqd
Poor in separating tiss d/t low viscosity

METHYL CELLULOSE

2% HPMC

Hydroxy propyl methyl cellulose

Source- Raw wood pulp

-cotton

Adv-

Low cost
Easy manufacturing
Autoclavable
Can be diluted & is hy drophilic-so can be easily irrigated from the eye

Disadv-req large bore cannula

POLYACRYLAMIDE

0.5%

Synthetic

Adv-

does not req refrigeration
low contact angle-more coatability

Disadv- long elimination time from the body[ spleen & liver]

COLLAGEN-

2% type I collagen

Source- human placenta

May cause allergy as it is a protein

CELLUGEL

Synthetic

Adv-

autoclavable
No refrigeration
can be injected with a 25 G cannula

Newer-Poly TEGMA-40%

-Poly GLYMA

USES OF VISCO-

1.cat Sx

-protects cor epith

-Control of capillary ooze

-AC maintainence

-Controlled ant C’tomy

-nucleus delivery by viscoexpression

-atraumatic intro of phaco probe & other instrum into AC

-Rx of expulsive h’age-forces IO contents back so that sutures can be placed comfortably

-coating of IOL

2.CME- restores IOP & prev edema

3. Glaucoma-1. G’tomy

2. trab

3. cyclodialysis

4.KP

5.retinal surg-replaces dis vit

-pushes detached ret closer to choroids

6.Trauma-sorting out tiss

-restoring nml shape

-raising IOP

7.Membrane sx

8.NLD block-maintain patency

S/E-

blockage of orifice
Retroirideal inj→ iris prolapse
reduced thermal convection
prev rapid spread of drugs in AC
rise in IOP

Diff from vitreous-

-vit does not stick to sponge or tiss so can be wiped away

-while removing visco,iris & pupil do not change shape whereas while removing vit,pupil peaks & iris moves

Ophthalmology Notes

SECTIONS

Ophthalmology Notes @ OphthalNotes.blogspot.com

COMMONLY USED DRUGS IN ENDOPHTHALMITIS

Phacotutorials.info

Phacoemulsification for Beginners

LENS NOTES

LENS

LENS DEVELOPMENT

LENS CRYSTALLINES [D-O4]

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