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Cataract Flashcards

1
Q

Lens is a biconvex transparent or crystalline disc that is situated between iris and vit humor suspended by suspensory ligaments
It has no blood supply and nerve supply
Gets nutrition from aqueous and vitreous humor

A
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2
Q

Anatomy of lens

A

3 parts
Capsule ie ant and post
Fiber: cortex and nucleus
Epithelium

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3
Q

Func of lens

A

1.Acts as refractive media and converges focus point to retina
2. Gives power to the eye +15D
3.helps in accomodation of near vision

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4
Q

Why lens is transparent

A

It contains highest amt of protein. These proteins are crystalline in nature, well arranged , tightly compact within the capsule so it does not change the position and also nothing can enter or exit through it. It is impermeable and thus transparent
It always remains in dehydrated state so it is transparent

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5
Q

How cataract develops in lens

A

It is so sensitive and reacts with minimum insult which is expressed by developing cataract

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6
Q

Cataract

A

Opacity of lens or its capsule

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7
Q

Pathogenesis of cataract

A

Increased permeability of the capsule
Leads to imbibitions of water and Na into the lens and loss of k+ protein amino acid
Protein loses its crystalline property causing opacity( immature cataract)
Opacity gradually increases turning white( mature cataract)
And into more white color ( hypermature cataract)
If no treatment then complications may arise.

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8
Q

Calssify cataract aetiologically

A

1.congenital
Due to torch infections of mother
Malnutrition

2.acquired
. Age related cataract… immature and mature
. Secondary cataract:
Includes toxic cataract
Complicated cataract : other ocular diseases like acute iritis, iridocyclitis, acute narrow angle glaucoma, retinal detachment.

Cataract due to systemic diseases like DM, atopic dermatitis , neurofibromatosis and myotonic dystrophy

Cataract due to trauma or injury
Includes heat cold electric shock

toxic or drug induced:
Steroid, pilocarpine , chlorpromazole, thalidomide

Metabolic : DM and galactosemia

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9
Q

Classify cataract acc to maturity or Clinically

A

1.Intumiscent- water enters the lens and it becomes swollen and prepares for opacity

  1. Immature: opacity in lens in some parts
  2. Mature : total lens opacity
  3. Hypermature : opacity increases more.
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10
Q

Classify cataract acc to position of opacity or anatomical

A
  1. Capsular cataract
  2. Sub capsular cataract
  3. Cortical cataract
  4. Nuclear cataract
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11
Q

What is the diff btw congenital and developmental cataract

A

In both cases pathology starts in intra uterine life but congenital cataract is manifested at birth and developmental cataract is manifested in developmental cataract

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12
Q

Normal colour of lens is transparent. Why does it show gray color

A

Due to vit humor in background
Which is dark and reflects from pupillary area showing gray color

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13
Q

What is secondary cataract

A

Cataract due to systemic diseases

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14
Q

What is complicated cataract

A

Cataract due to other ocular diseases

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15
Q

Toxic cataract

A

Due to toxic effects of drugs

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16
Q

Why cataract occurs in oldage

A

In oldage Atp production reduces through citric acid pathway
Body tries to compensate atp by alternate pathway for compensation by anaerobic glycolysis.
Lactic acid is produced more
Protease production increases
Breakdown of lens protein
Crystalline property of lens is lost.
Cataract occurs

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17
Q

How blood sugar increase causes cataract

A

In DM sugar in blood increases
Glucokinase and hexokinase become saturated
Sugar converts to sorbitol
Sorbitol converts to fructose
Fructose causes imbibition of water inside the lens and fructose is deposited inside the lens
Loss of impermeable capability
Protein arrangement is lost
Lens develops cataract

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18
Q

How is atopic dermatitis related to cataract

A

Skin and lens both are developed from surface ectoderm
So if skin is affected lens is also effected

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19
Q
A
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20
Q

Clinical features of cataract

A

1.Gradual or progressive dimness of vision
2.Painless no watering no photophobia
3.Usually bilateral in case of age related cataract
4.Halo: it is a coloured ring around light because fluid accumulates and causes dispersion of light
5.Diplopia or polyopia

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21
Q

Signs

A

Visual acquity
Immature reduced to finger count
Mature reduced to hand movement
Hypermature reduced to perception of light or projection of rays

Color of lens
Immature: grayish white
Mature: pearly white
Hypermature: milky white

Iris shadow:
Immature: present
Mature absent
Hypermature absent

In ophthalmoscope:
Immature: black spot against red
Mature absent
Immature absent

22
Q

Iris shadow

A

Crescenteric shadow of the pypillary margin of iris over the partially opaque lens

Procedure: light is thrown obliquely on limbus
Shadow falls on lens
Crescenteric in shape and falls on the same side of light from which it is thrown

23
Q

Diagnosis and investigations

A
  1. Local
    Intraocular pressure
    Sac patency test
    Pupillary rxn
    Macular func test
    Perception of light projection of rays
    Conjunctival swab
    Biometry
    Retinal examination
  2. Para local
    Dental check up
    Sinusitis
  3. Systemic
    Fasting blood sugar
    Blood pressure
    Conjunctival swab
    Ecg for elderly
    Dental checkup
24
Q

Why do we check intra ocular pressure

A

For prognosis
If iop is raised and during surgery inscission is given then the ocular contents may leak out

25
Why sac patency test
To see lacrimal drainage pathway To rule out presence of dacryocystitis
26
Why pupillary rxn
If pupil is dilated it indicates optic nerve is damaged
27
Why macular func test
If macula is healthy cone cells are intact and post operative vision is normal
28
Why plpr
To see if macula is healthy or not Among 4 quadrants nasal quadrant is more imp as light falls on temporal side
29
2 light discrimination test
2 lights from 10 cm away are jointly thrown on a single point in pt. Then slowly separate the light from each other If pt can understand 2 lights separately Test is positive
30
Maddox rod test
Instruct pt to close his left eye Rod containing plate is kept in front of the pts right eye vertically which contains vertical or transverse rod Instruct patient to look at the light In healthy person if the rods are placed vertically then transverse lines are seen and if rods are placed transversely then vertical lines are seen which are continuous In disease of macula the continuous lines are distorted
31
Biometry
It is the method of measurement of the power of intra ocular lens Srk formula Sanders rezlauf and krauf formula A-(B×AL) -(C×K) Here A is lens constant and its value is 118-118.7 B=2.5 C=0.9 AL Is the axial length ie the distance of retina from cornea Measured by A scan. Normal is 20 -24mm K is the corneal power measured by keratometer Normal is 43D 2 dimensional measures k1 and k2 P= power of intra ocular lens Normally +20D
32
Complications of cataract surgery
1. During anesthesia .involuntary penetration of eyeball .retrobulbar hemorrhage 2. Peroperative complications .rupture of posterior capsule .Vitreous loss .iris prolapse .retinal detachment .shallow ant chamber .injury to corneal epithelium .hemorrhage 3.post operative . A.EARLY COMP shallow ant chamber Iritis Corneal haziness Corneal edema Anterior chamber Hyphaema Glaucoma B. LATE COMP Posterior capsular opacity Persistent chronic uvietis Retinal detachment Displacemment of lens Macular edema Severe astigmatism Secondary glaucoma
33
Treatment
In early stage: spectacle correction In late stage: surgery Surgery: extracapsular cataract extraction with posterior chamber intra ocular lens implantation Types: conventional Small incision cataract surgery Phacoemulsification
34
Preoperative medication
1. Tropicamide 0.5% with phenylephrine 5% eyedrop 1 drop 3 times at 10 mins interval Acts as mydriatic Tropicamide is a short acting anticholinergic drug which paralyses sphincter pupillae Phenylephrine causes stinulation of dilator pupillae resulting in further dilatation 2.tab acetazolamide 2 tab 3 hrs before operation It is carbonic anhydrase inhibitor Prevents h+ and hco3 production needed to produce aq humor Decreased aq humor decreases iop 3. Tab electro K Prevents hypokalaemia due to acetazolamide 4. Moxibac eyedrop Prophylactic antibiotic
35
Post op meds
1. Antibiotic eyedrop moxifloxacin gatifloxacin levofloxacin 1 drop 4 times daily 1 month 2. Steroid eye drop dexamethasone 1 drop 6 times daily for 1 n 1/2 months Tropicamide: 1 drop 2 times daily for 7-10 days Systemic antibiotics Tab acetazolamide with electro k given for 24 hrs
36
Steps of phacoemulsification
1. Anesthesia followed by digital massage Surface anaesthesia- 0.4% oxybuprocaine eyedrop Local anesthesia 6 ml peribulbar block 2% xylocaine rapid onset short acting 5% bupivacaine late onset long acting Hyaluronidase spreading factor 2.sterlization and drapping 3. Application of wire speculum 4. Incision- phaco corneal tenporal tunnel incision 3 mm phaco knife 5. Trephine blue dye is injected if there is need of identification of anterior capsule 6. Reform anterior chamber by visco elastic substance 7. Continuous circular capsulorexhis ie excision of ant capsule 8.hydro dissection separation of capsule from cortex and nucleus 9. Hydro delineation separation of nucleus from cortex 10.in case of phaco make side port to control movement of nucleus 11.nucleus is emulsified and removed by phacomachine 12.irrigation and aspirationof cortex by rls and normal saline 13.visco elastic substance is again given from capsular bag 14. Lens implantation in phaco it is foldable lens 15.irrigqtion and aspiration to clear visco elastic substance because it increases iop 16. In phaco no stitch is needed 17. Pad banadage is not needed
37
Adv of ecce
Posterior chamber intra ocukar lens can be implanted on intact posterior capsule Less chance of vitreous loss Less chance of endophthalmitis Less chance of retinal detachment Less chance of macukar edema
38
Disadv of ecce
Opacification of posterior capsule More chance of post op iridocyclitis It cant be done in dislocation abmnd sublaxation Needs costly operating microscope
39
Adv of phacoemmulsification
1. Daycare surgery so early return to job Less astigmatism Less infection Less complications No stitch or pad bandage
40
Dis adv of phacomulsification
Skilled surgeon needed Expensive Difficult to do in hard cataract
41
Icce adv
Relatively easy simple quick cheap No chance of uvietis and secondary glaucoma Cosmetically looks better
42
Icce disadv
Pciol implantation not possible Chance of retinal detachment is more
43
Complications of cataract if we dont do surgery
Sublaxation or dislocation of lens Iritis or iridocyclitis Phacomorphic glaucoma Phacolytic glaucoma Morgaganian cataract Dystrophic calcification
44
Phacolytic glaucoma
In hypermature cataract No regularities in lens protein Increased entry of water into lens making cotex more liquefied and increased permeability of capsule causing protein to come out This results in protein to come out within anterior chamber Which is engulfed by macrophage Size of mq increases Mq along with free cortex blocks the trabcular meshwork and decreases drainage of aq humor increasing iop
45
Treatment of phacolytic glaucoma
Control of iop By tab acetazolamide 2 tab stat and 1 tab 6 hrly Tab electro k Tinolol eyedrop 1 drop 12 hrly Iv manitol Surgery Phacoemmulsification with or without intra ocular lens implantation Small insission cataract surgery
46
In sublaxated or dislocated lens
Do icce and put in ant chamber or lens in post chamber with suturing to sclera called schleral fixation
47
Congenital cataract causes
Idiopathic Maternal malnutrition Heriditary Torch inf Syphilkis Chr abnormality ds Developmental defect of lens
48
Clinical features of congenital cataract
Leuvochorea Nystagmus Squint Amblyopia
49
Signs of cong cataract
Opacity of lens seen after dilatation of pupil
50
Treatment
If bilateral dense cataract Surgery must be done asap If children Soft cataract without nucleus Surgery is 1.needle aspiration of cortex with removal of cataract 2. Pars plana lensectomy and. Posterior circular capsulorhexxhis and anterior vitrectomy followed by spectacle correction followed by secondary iol implantation Procedure Removal of ant capsule and cortex Make a hole on post capsule Removal of vitreous humor from ant part of post capsule Spectacle correction Counselling of mother Specs used upto 3 yrs Lens implantation
51

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