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Med Prep > ophtha-lens and vitreous > Flashcards

ophtha-lens and vitreous Flashcards

0
Q

Part of lens

A

Central hard nucleus

Peripheral soft cortex enclosed by a capsule

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1
Q

Crystalline biconvex structure

A

Lens

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2
Q

Lens is held in position by

A

Zonular fibers (from ciliary body that fused with capsule at region of equator)

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3
Q

Where does the lens nuclei located?

A

Equator

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4
Q

Lens has sparse or numerous cells?

A

Sparsely cellular

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5
Q

Embryological origin of lens

A

from ectoderm from lens plate of 2 wk old embryo which becomes lens vesicle

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6
Q

Cells of anterior wall of lens vesicle will become

A

Sub capsular epithelium

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7
Q

Cells of posterior wall of lens vesicle will become

A

Primary lens fiber (which begins to fill in the cavity of vesicle to constitute the central region “central dark interval”)

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8
Q

Cells of equator of lens vesicle will become

A

Secondary fibers (which grows to surround embryonic lens)

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9
Q

Optical system of eye

A

Lens and cornea

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10
Q

When ciliary ms relaxes, zonules become tense, lens thinner = focused beyond retina = HYPEROPIA

A

When ciliary ms contract, zonules loosen, lens thicker = focused beyond retina = MYOPIA

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11
Q

Lens has passive/active metabolism

A

Active metabolism as shown by its high protein

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12
Q

Lens has no blood vessels, nutrition is from..

A

Aqueous thru selective osmosis

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13
Q

Sole source of energy of lens

A

Carbohydrates

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14
Q

What are the conenzymes found in glycolysis during anaerobic condi

A

ATP

DPN diphosphoridine nucleotide

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15
Q

Color of lens

A

Pale yellow

Darkens with old age

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16
Q

At old age.. What metachromatic color has difficulty reaching the retina?

A

Blue and violet metachromatic

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17
Q

In old age with change in color perception, the Blue color becomes ___

A

Green

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18
Q

Change in color perception is due to

A

Accum of metabolizes of aa, tryptophan

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19
Q

Factors that contributes to transparency of lens

A

Regular parallel arrangement of fibers with the nuclei at periphery
Curvature of surfaces
Refractive capsule
Location of geometric center at middle
(And in addition, smooth, gradual blending of refractive indices-capsule,cortex and nucleus)

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20
Q

Any disturbance such as . . . Will cause lens opacities or cataract

A

Change in curvature
Insinuation of water between individual fibers
Deposition of substance in capsule

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21
Q

Metab changes in lens is due to

A

Increase in Na and Ca content or
Decrease in K, glutathione ans as orbit acid content
(Which may lead to cataract)

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22
Q

Cataract is caused by

A

Metab changes
Permeability disturbance
Changes in aqueous, vitreous and ciliary body
(Other: heredity, racia predisposition, malnutrition, light, heat, radiation and endocrine disturbance)

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23
Q

How does cataract formed in diabetics

A

Hyperglycemia increases reduced sugar (sorbitol) in aqueous and by osmosis, it withdraw some water from lens.

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24
Q

How does cataract formed in changes in ciliary body

A

Catalytic changes in ciliary body which is responsible for increased formation of aqueous with the aid of carbonic anhydrase

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25
Q

Congenital absence of lens charac by small eyes (microphthalmic)

A

Aphakia

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26
Q

Diagnosis of aphakia

A

Presence of deep anterior chamber
Tremor of iris (iridodenisis)
Absence of purkinje image

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27
Q

Corneal and scleral scar, coloboma of iris and eccentric or irreg pupil may be present

A

Aphakia

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28
Q

Ophthalmic exam of fudge requires the need of high plus lens, approx..

A

+10 D

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29
Q

How is accommodation in aphakia

A

Completely lost

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30
Q

Lens used to focus rays of light in retina

A

Aphakia bifocal lens

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31
Q

T/f. In Monocular aphakia, wearing spectacles will not restore the binocular vision

A

True. Because of disparity of image size (anisokonia) between 2 eyes

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32
Q

Disparity of image size between 2 eyes

A

Anisokonia

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33
Q

Small lens with tendency to be spherical (spherophakia)

A

Microphakia

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34
Q

Microphakia is asso with

A

Ectopia lentis

Congenital weakness of zonules

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35
Q

In microphakia, when the pupil is dilated, the edge of Lens is seen all around the circumference of pupil = highly myopic

A

Microphakia is hereditary, recessive

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36
Q

Indentation or defect of lens equator asso with absence of zonule fibers

A

Lens coloboma

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37
Q

Spherical protrusion of ant or post portion of lens producing visual impairment

A

Lentiglobus

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38
Q

Lentiglobus vision is improved by

A

Refraction or lens extraction

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39
Q

Occurs as asymmetrical defect of zonule so lens is displaced away from the defective zonule fibers (as seen in semi dilated pupil)

A

Lens dislocation

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40
Q

Deep form of ectopia lentis is

A

Congenital

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41
Q

Lens dislocation is common in

A

Arachnodactyly or marfan’s syndrome

Charac by extreme length and thinned of bones, ms weakness and miosis

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42
Q

If lens dislocation is due to trauma, lens is displaces toward…

A

Inferior (for zonules affected are superior)

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43
Q

If lens dislocation is developmental type, lens is displaced..

A

Upward

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44
Q

S&s in lens dislocation

A

Blurring
Iridodenisis
Monocular Diplopia (if lens equator is seen at pupil)
Glaucoma (if ciliary body us irritated)

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45
Q

A gradual and progressive dse charac by Any opacity of lens with visual impairment

A

Cataract

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46
Q

Most common complaint in cataract

A

Cloudiness of vision

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47
Q

By presbyope so who’d discovered that they can read small fine prints without aid of their old reading glass

A

“Second sight”

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48
Q

Second sight is due to

A

Lenticular myopia form change of index of refraction

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49
Q

Principal objective sign in cataract

A

Lens opacity

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50
Q

In early nuclear sclerosis in cataract

A

Iris shadow

51
Q

What can you see in ophthalmoscope in cataract

A

At distance may show black spots in fundus reflex against orange-red background

52
Q

What can u see in ophthalmoscope when the lens is completely opaque

A

No fundus reflex

53
Q

Dz procedure to determine the nature and position of the opacities in lens

A

Biomicroscopy

54
Q

Type of cataract asso with local eye pathology (corneal infection, uveitis, glaucoma, vitreous hemo, retinal detachment, retinitis pigmentosa and tumors)

A

Complicated cataract

55
Q

In complicated cataract, the opacities begins..

A

Beneath the capsule (as a result of changes in capsular permeability)

56
Q

Is visual outcome of lens extraction in complicated cataracts can’t be predicted?

A

Yes

57
Q

“After-cataract” “membranous cataract”

A

Secondary cataract

58
Q

Type of cataract with opaque membrane due to incomplete absorption of lens ff trauma or incomplete surgical removal of lens

A

Secondary cataract

59
Q

Type of cataract which is generally bilateral, opacity localized in ant or post pole and lamella may be involved

A

Hereditary type of developmental cataract

60
Q

Most common type of hereditary type of developmental cataract

A

Ant axial embryonal cataract (appearing S&s multiplr fine opacities surrounded by faint halo)

61
Q

It affects pregnant mothers during first trimester (maternal illness during fetal life)

A

Rubella (lens is isolated for 3 yrs after birth)

62
Q

Hypothyroidism is asso with developmental cataract. What is its essential feature?

A

Low ration of Ca to P in bld

63
Q

Some contraceptive drug have been found to induce cataract formation, such drug as ..

A

Thalidomide

64
Q

Lens begins to lose its transparency with aging process

A

Senile cataract

65
Q

Type of senile cataract where in the oldest fibers in center of lens lose their transparency

A

Nuclear (sclerotic type)

66
Q

Type of senile cataract where in opacity involves outer layers

A

Cortical cataract

67
Q

Type of senile cataract which tends to become hard and shrunken

A

Nuclear cataract

68
Q

Type of senile cataract tends to swell and liquefy

A

Cortical cataract

69
Q

Systemic cataract may be due to

A

DM

Hypothyroidism

70
Q

Management for cataract

A

Surgical removal

71
Q

Indication for surgical removal of cataract

A

Inability to perform usual work with aid of spectacles

Development of secondary glaucoma and uveitis

72
Q

Binocular vision is attained only with aid of contraindication tact lens or intra ocular lens

A

Unilateral cataract

73
Q

In young, surgery should be done ASAP if..

A

Both eyes have poor vision

Strabismus sets in

74
Q

Young with cataract are prone to complications

A

Retinal detachment
Uveitis
Glaucoma

75
Q

In rubella cataract, surgery is done

A

After 3 yrs

76
Q

At what age will the zonule become hard to break, or be broken?

A

Before 40 y/o, zonule fibers are hard to break

After 20 y/o, zonules may be broken with aid of alpha-chemo trypsin

77
Q

Method of cataract extraction where capsule breaks

A

Extracapsular extraction

78
Q

Method of cataract extraction where lens is removed with capsule intact

A

Intra capsular extraction (not possible if pt is <20 y/o)

79
Q

Ant capsule of lens is cut crosswise. The small knife is passed thru small puncture of cornea.

A

Discission

80
Q

Extra capsular method procedure where ant capsule is ruptured. Lens subs is stirred by the same point instru used in penetrating cornea

A

Needling

81
Q

Extra capsular method procedure done in young, where ant capsule is removed ASAP and the hard nucleus is expressed out. Bigger corneal wound is made.

A

Capsulectomy

82
Q

Aka linear extraction because of linear corneal incision

A

Capsulectomy

83
Q

Extra capsular method procedure where special app is that can be introduced anterior and post to lens with their rotating sharp edge slowly tearing the lens capsule and subs into small bits then aspired out

A

Lensectomy

84
Q

Extra capsular method procedure where it uses special type of app used to dislocate anteriorly, fragments it by ultra vibration and finally aspirated the resulting small particles out

A

Phacoemulsification

85
Q

Extra capsular method procedure that utilizes probe frozen -20 C

A

Cryoextraction

86
Q

Extra capsular method procedure which uses lens capsule forces

A

Forcep extraction

87
Q

Extra capsular method procedure which uses metal suction tip

A

Phakoeresis

88
Q

Gel-like subs and constitutes the main bilk of eyeball

A

Vitreous

89
Q

Volume of vitreous

A

4ml

90
Q

The gel-like consistency, of oddity and viscosity of vitreous is due to

A

Due to a double fibrillation network system of collagen-like protein and hyaluronic acid which is suspended in large amt of water

91
Q

Vitreous has the firmest attachment to the pars plana and retinal periphery

A

Vitreous base

92
Q

Vitreous base extends __ mm anterior to ______

And from posterior to _____.

A

2mm anterior to Ora serrata on pars plana

And from posterior to Ora serrata on peripheral retina

93
Q

Vitreous is also attached to (but less firmly )

A

Optic disk margin
Macula
Post peripheral surface of lens

94
Q

Post peripheral surface of lens is called

A

Hyaloidocapsular ligament of Weigert

95
Q

Anterior condensation of peripheral vitreous forms

A

Anterior hyaline membrane

96
Q

Potential space between Lens and anterior hyaloid

A

Space of Berger

97
Q

The cortical or outer layer of vitreous contains Small no of cells called..

A

Hyalocytes

98
Q

Source of hyaluronic acid and has phagocytic effect

A

Hyalocytes

99
Q

Embryological origin of primary vitreous

A

Protoplasmic processes of the lens vesicles and inner layer of optic cup

100
Q

Mesenchymal cells enter the region of optic cup to contribute to ..

A

Primary vitreous

101
Q

Formed by 9th wk by activity of vitreous and retinal cells

A

Secondary vitreous

102
Q

Forms bulk of postnatal vitreous

A

Secondary vitreous

103
Q

As the secondary vitreous increases in vol, the primary vitreous is forced forward to central position, the site of ?

A

Cloquet’s Canal

104
Q

Produce by margin of growing optic cup which later becomes suspension ligament of lens

A

Tertiary vitreous

105
Q

3 main symptom on pathology of vitreous

A

Positive scotoma
Photopsia
Impairment of vision

106
Q

Flashing spots in field of vision

A

Positive scotoma

107
Q

Light flashes esp on movement of eyeball

A

Photopsia

108
Q

It is due to cast on retina by opacities floating in vitreous

A

Positive scotoma

109
Q

It is due to much traction and/or prsessure in retina by partially detached vitreous body

A

Photopsia

110
Q

It is due to opaque particles in vitreous

A

Impairment of vision

111
Q

What can u see in ophthalmoscope in pathological vitreous

A

Scattered floater or opacities may appear black against red fundus reflex

112
Q

IFN pa cities are more numerous and extensive, the fundus reflex is

A

Lost

113
Q

Partial or complete failure of embryonic hyaloid vascular system to regress which produces white pupil in small eye

A

Persisted hyperplastic primary vitreous

114
Q

Lost of gel-like consistency or conversion of vitreous into liquid

A

Vitreous liquefaction (syneresis)

115
Q

Gel-like conversion of colloidal struc of vitreous (which occur on aged, myopic, in trauma and inflammation)

A

Vitreous liquefaction (syneresis)

116
Q

This occurs when vitreous liquefaction results to separation of surrounding tissue (esp retina)

A

Vitreous detachment

117
Q

Most common symptom in vitreous detachment

A

Photopsia or floater

118
Q

Is vision not threatened in vitreous detachment?

A

Yes. Unless asso with retinal tears, detachment or vitreous hemorrhage

119
Q

Vigorous opacities is caused by

A

Inflammatory cells (post uveitis, endophthalmitis)
RBC (vitreous hemo)
Saponified Ca soaps (asteroid hyalitis)
Cholesterol crystals (synchisis scintillans)
Tumor cells (RB)
Foreign bodies ff pentrating injury

120
Q

Symptom of vitreous opacities

A

Seeing spots in field of vision to actual diminution of vision of varying degree

121
Q

Caused by fine aggregates of vitreous protein due to age or myopia

A

Musca volitantes

122
Q

Seen as floater spots darting ms and out of field of vision (esp when gazes is focused in an illuminated background)

A

Musca volitantes

123
Q

Condensation of fibrillation struc of vitreous or actual fibroblastic or glial proliferation from vascular elements. Pigments epith cells is also the source

A

Vitreous band and membrane

124
Q

Vitreous band is commonly seen in

A

Diabetic retinopathy or ff long standing vitreous hemorrhage

125
Q

Thru corneal incision and aphakic pupil

A

Open vitrectomy

126
Q

Vitrectomy Thru pars plana

A

Closed vitrectomy

Med Prep (52 decks)

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