Oftalmo 1st test Flashcards
Dimensions of the eye?
23.5mm x 23mm (vertical), 22-24mm (AP)
Size matters for refraction
weight of the eye
7.5g
2 poles of the eye
○ An equator - maximum circle perpendicular to AP axis
○ 2 meridianos: § Anterior pole - □ center of the cornea, □ transparent □ Most external layer □ avascular
§ Posterior pole □ Retina and optic nerve □ Most internal part □ To see these parts have to dilate the pupil
What are the 3 cameras of eye?
to have good vision all cameras need to be transparent
anterior
posterior
vitrea
anterior camera
between iris (color) and cornea
○ the aperture of iris = pupila, ○ Contains aqueous humor ○ Measures 3mm deep ○ Volume of 250 µL. ○
posterior camera
medial to iris and ciliary body, anterior to crystalline lens and vitreal cavity,
○ 60uL volume
○ 4.5mm deep
○
○ (No hay medio acuoso casi, solo lente).
vitrea
constitutes > 2/3 of volume of eye
○ Contains vitreal gel
○ 5-6ml
○ Gives form to eye
What happens When there is an increase in production of aqueous humor or when there is no proper drainage?
–> increase in intraocular pressure and affection of II
Define catarats?
- when in this (post camera ) area, crystalline lens opacifies
What do zonulas do?
- Permit accomadation of lense
- With age this decreases –> presbicia
The zonule of Zinn (Zinn’s membrane, ciliary zonule) (after Johann Gottfried Zinn) is a ring of fibrous strands connecting the ciliary body with the crystalline lens of the eye. These fibers are sometimes collectively referred to as the suspensory ligaments of the lens.
Only thing that detaches?
Retina
How to see II?
neuroimages
embryological development of the eye
- Formed in day 25 from optic fossettes
- Derived from prosencefalus
- Differentiates in days 26-28 in optic vesicles
sturctures of the eye from the neuroectoderm?
retina, II, sphincter muscles, dilator of iris, posterior iridian epithelium, epithelial ciliar body
sturctures of the eye from the superficial ectoderm?
crystalline, corneal epithelium, eyelid epidermis, lagrimal gland and tarsal/eyelid conjuntiva (covers eyelids, bulbar conjuntiva which covers sclera)
sturctures of the eye from the neural crest or ectomesenquim?
keratocytes, scleral fibroblasts, trabeculum endothelium, coiroid stroma, iridian, ciliar SM, meninges, orbital fibroadipous tissue, carillage, and orbitary bones
sturctures of the eye from the mesoderm or mesenquime?
extraocular muscles and vascular endothelium
3 layers of the eye
external: cornea sclera
middle: uvea
internal: retina
cx of cornea
§ Most external
§ Normally transparent
§ avascular
§ 6 layers (stratified)
§ Trigeminal innervation § : ○ 90% del espesor corneal: colágeno y queratocitos, .
cx of sclera
§ Continues with meninges and DM
§ CT , dense, similar to cartilage
§ Avascular
§ Insertion of extraocular muscles § Lamina cribosa at posterior part - exit of optic nerve fibers
uvea cx
§ Anterior: iris and ciliar body
§ Posterior: coroides
Only part of eye transplanted? Only part that hurts?
cornea
6 layers of the cornea
stratirifed
○ se descubrió una sexta capa que se encuentra entre descemet y el endotelio, la capa dua.
Epithelium.
Bowman’s.
Stroma. ○ Lesion here or deeper –> leocoma = scar
Dua’s layer.
Descemet’s.
Endothelium.-: maintaines corneal dehydration (avoid blurry vision).
function of sclera
structural support of eye
what forms the sclera
§ Formed by external episclera (very vascularized) and stroma (avascular without innervation)
What gives nutrition to cornea?
- Pelicular lagrimal
What causes scar of cornea?
- Lesion of endothelium
What causes corneal edema?
- Lesion of endothelium
Mientras más acentuado el edema, mayor disminución de la agudeza visual, dado que este es el que mantiene la deshidratación corneal
Corneal Pannus
@ rheumatological process –> Ag/Ac @ conjuntiva so conjuntival vessels invade cornea
vascularization of avascular cornea
innervation of eye
- Opthalmic
- Some penetrate thru subconjuntival and episcleral
- Most penetrate thru sclera
irrigation of eye
- Peripheral cornea are irrigated by conjuntival , episcleral and scleral vessels
- Avascular cornea
- Perforations for vorticose veins, short ciliar arteries and large ones –> irrigation to sclera
3 layers of sclera
- Episclera
○ CT, rotation- Stroma/fibrous layer
○ Avascular
○ Densely innervated by branches of posterior ciliary nerves - Fuscia Lamina
○ Most internal - abundant vessels
- Stroma/fibrous layer
How is endocraneal HTN seen ?
papiledema
Name of transition zone between cornea and sclera?
clercorneal limbo
- With structures that drain acuous humor or trabecular malla - Localized in irido-corneal angle where humoracuous passes to schlemm canal - Arrives to collector channels of episcleral veins - Causes that increase humoral pressure (aysmptomatic --> irreversible damage)
what is pterigon
growth of conjunctiva that invades cornea
- Hipertrophy of conjuntiva that invades the córnea - Not all are operated , the younger the px the more chance of scarring - Are removed if grow too fast, if irregular , if irritate, if inflame frequently, if px doesn’t want it - Can become malignant, with conjuntival CA which confuse, differentiate them by rapid growth, coloration and border irregularity, should biopsu
most vascularized part of eye
uvea
what is the ciliar body
part of iris and is what allows it to open or close
what produces aqueous humor
Aqueous humor is produced by the ciliary body and it flowsfrom the posterior chamber through the pupil into the anterior chamber
part of eye that gives color
iris
Central opening of the iris?
pupilla
innervation of pupila
- Sympathetic - midriasis
- Parasympathetic - miosis
Vascularized layer between sclera and retina?
coroides
layers of coroides
- External layer w/ grand coroid vessels
- Internal layer = coricocapilaris - gives nutrients to external third of retina
- Internal limiit is Bruch membrane that seperates coriocapilaris from retinal epithelium.
what makes up ciliary body
§ Made of ciliar muscle (fibras musculares lisas radiales y circulares )that allow accomodation of crystalino/lens (ZOOM)
cx of iris
§ Made of lax stroma with pigmentated cells and smooth muscle
§ Surrounded by anterior epithelium and posterior one (pigmentary) from which come the melanocytes.
□ Albino have pink eyes - no melanin iris is so clear
cx of coroides
§ Below retina
§ Extends forward with ciliar body
§ Abundant melanocytes
cx of retina
- Transforms light in nerve impulse
has cones and bastones
10 layers of retina
- Epitelio pigmentario
- Capa fotorreceptora
- Membrana limitante externa: sostén
- Granulosa externa: Núcleos fotorreceptores
- Plexiforme externa: sinapsis entre bipolares y fotorreceptores.
- Granulosa interna: núcleos de células bipolares
- Plexiforme interna: sinapsis entre las células ganglionares y células bipolares y de las células amácrinas entre ambas
- Capas células ganglionares: núcleos de estas
- Capa de fibras nerviosas axones células ganglionares
- Membrana Limitante interna: Membrana basal
pars plana vs pars plicata
- Pars plana - [posterior part with ciliar muscle) –> pars planitis or intermediate uveitis
(Latin: flat portion) is part of the ciliary body in the uvea (or vascular tunic), the middle layer of the three layers that comprise the eye.
As a part of the ciliary body, it is about 4mm long, located near the point where the iris and sclera touch and is scalloped in appearance.
The pars plana may not have a function in the post-fetal period, making this a good site of entry for ophthalmic surgery of the posterior segment (pars plana vitrectomy).- Pars plicata - (anterior part with ciliar processes) –> anterior uveitis
(Latin: folded portion) is the folded and most anterior portion of the ciliary body of an eye.
The ciliary body is a part of the uvea, one of the three layers that comprise the eye. The pars plicata is located anterior to the pars plana portion of the ciliary body, and posterior to the iris. The lens zonules that are used to control accommodation are attached to the pars plicata.
The pars plicata is the portion of the ciliary body that is responsible for producing aqueous humor, the fluid of the anterior chamber.
The production of too much aqueous humor, or reabsorption that occurs too slowly, can lead to increases in the pressure within the eye.
- If it affects both = pan uveitis Panuveitis: a serious inflammation of the uveal tract of the eye. The uveal tract includes the iris, the ciliary body, and the choroid. Panuveitis also typically involves the retina and the vitreous humor. Panuveitis can be caused by infections, chronic inflammatory diseases, or its cause may be unknown.
cones vs bastones
- Has specilized cells called cones to discriminate sight and color, in fovea
Cones?- Contain rodospine making them sensible to light
- Rodopsine is the aldehyde form of vitamine A (absorbs light)
- Cones - detect form and color, occupied in diurnal vision and their loss causes legal blindness
- Bastones - regulate nocturnal vision
- Has bastones to discriminate between light and darkness
Queratitis
- Inflamations of the cornea
- Can be bacterial, viral, micotic, actinic (from radiation)
MC of corneal lesions?
- Red eyes,
- Pain
○ The only thing that hurts in eye is the cornea due to trigeminal innervation ,
○ Ocular pain from spasms of ciliar muscles and iridian sphincter - fotofobia,
- blefarospasm
- ciliary injections
○
Can have corneal ulcers: - Hipopion - pus in anterior camera -
○ don’t drain only
○ topical ATB and systemic - hospitalize px - Hipema - blood in anterior camera - drain
- Pain
causes of infectious queratitis
bacterial
fungal
virus
bacterial queratitis
§ No drop steroids - delays recoverey?
○ Contact lenses
○ Edema of cornea, grey borders vascularized, hipopion
○ Staph, aureus, neumococo, streptococous, pseudomona, moraxella
○
viral queratitis
○ High association with HSV I (95%) - facial?
○ Vesicular lesions in eyelid , nose, mouth maybe
○ Epithelial affection mostly
○ Dendtritic lesions - clinical determination for dx
○ NO STEROIDS - get worse
fungal queratits
○ Associated with vegetal trauma ○ Aspergillus ○ Satelite lesions ○ Little inflamation ○ Acanthamoeba: in contact lense users
management of viral queratitis
§ Topical & oral aciclovir 5x/d
§ Cycloplejics
§ Ocular lubricants
what is a geographic ulcer
○ When a dendritic ulcer grows losing lineal aspect
○ Associated with inadecuate use of steroids which favor viral replication
○ En estos casos, existe un defecto amplio que tiñe con fluorosceína.
non infectious queratits
- Traumatic - secondary to abrasion or simple erosion, burning, FBs, recidivant erosion
- Chemical toxic substances
- Physical (UV rays, sun, soldadura)
- Exposure Queratitis - due to bad eyelid closure usually from ectropion
management of noninfectious queratits
○ Frequent lubrication
○ Ocular parchado
○ Qx - SOS
○ Midriatic SOS
○ Topic steroids - if there is no epithelial lesion
§ Fluor-negative - steroids to disinflame
§ Fluor- possitive - no steroids
corneal dystrophies
- Bilateral anomalies,
- progressive,
- hereditary,
- painless,
- no systemic illness
- Opacity of cornea due to degeneration –> agudez visual
what are queratocones
- A type of dystrophy like a cone (not concave)
- Contact lenses to flatten or transplant
- Operate after 8yrs when eye reaches appropriate size
”) es una condición no habitual, en la cual la córnea (la parte transparente en la cara anterior del ojo) está anormalmente adelgazada y protruye hacia adelante.
Arco senil o gerontoxon:
- Deposit of lipids in the cornea - normal - in old px agining - if young must investigate lipid profile
Gerontoxon is an abnormal change in the perilimbal areas involving both cornea and sclera, consisting of lipid deposition into the spaces between cells and intracellularly in advanced instances
ciliary injections
Ciliary injection involves branches of the anterior ciliary arteries and indicates inflammation of the cornea, iris, or ciliary body.
○ VC in ciliar injection px --> gets white ingurgitated deep vessels remain § (VISINE CI until dx because uveitis or FB white but inflammation continues and you lose alarm signs)
you have an infectious process
hiperemia
Hiperemia - red eyes –> gets white with VC
estas te enrojecen el ojo pero no te ingurgitan los vasos,
VC generally used
fenilefrine,
nafazoline in drops
To dx cornea epithelial ulceration
○ Flurozine - green = active
if not its old
§ White lesion with flurosceine and remaines = scar - px ulcerated and remains with a leucoma
Management of bacterial corneal ulcers?
§ Cycloplejic - □ apart from dilating pupils □ Paralyze ciliar body □ Last 48-72hr vs midriatics last 4-6hr § Antibiogram § Fortified ATBs - Tobramycin drops with ampolla of ATB § Subconjuntival injections § Oral analgesics § Ocular lubricants
Scleral pathologies are associated with?
- RA
- Steven Johnson
- Lupus
Epiescleritis is?
inflamation of episclera (between insertion of rectus and the limbo) that generally affects 30-40yr women.
- Seen as a circunscrit hiperemic elevation - More diffuse
Tx of epiescleritis?
○ Topical and oral AINES
- If you put a VC in eye it will clear up even tho inflammaed part /ingurgitation will stay circunscrit, its what will allow you to differentiate something superficial or something deep like this pathology
Difference with Scleritis?
- Pain
- Bilateral
- More localized
- Don’t whiten with VC
- More tendency to recidivar
- Between 40-60yr, women
- Diffuse or nodular
- 70% unknown etiology
Tx of scleritis?
topical steroids or oral ones
Necrotizing Scleretis?
has a plaque of severe thinning of sclera
Anterior Uveitis?
- Affects the iris and anterior part of ciliar body (pars plicata)
- Management of AU?
○ Infectious analytics
○ Odontological evaluation
○ PA thorax x ray
○ Topical steroids
○ Cycloplejics - relax ciliar body and iris and pain foes away
§ Don’t put midriatics, shorter 4-6hr, only opens iris but doesn’t affect ciliar body
§ Cylclo alone - takes away pain but puil still dilated, still inflammed
§
What are sinequia?
- Affection of eye in the iris presents adherences to cornea (anterior sinequia) or lens (sinequiq posterior)
Called seclusion when?
They are 360 degrees, occurs when musculature sticks to iris or lens
Intermediate Uveitis?
- Usually with vitiritis
- Cx by decrease much higher in visual acuity
- Most difficult to dx because cant know if just vitro or other also affected
Posterior Uveitis?
- Affect suprajacent retina, coroidis
- Lower acuity
- Present floculos = copos de neives
○ . - Celularity and vitreal opacity
○ Same as anterior uveitis but in this case its in the vitreo
○ If manges to become so severe can present “Copos de nieves” - Vascularity
associated with rheumtalogical diseases
- Coroiditis: these have yellow grey focuses , differentiating itself from opacity of uveitis which is white - Uveitis has to progress to get coroiditis
floculos
Floating flies or artefacts , can be hilos
○ Most are not pathological, only says that vitreo detached a protein but when it happens wit decrease In visual acuity that’s when we think its pathological
What is the conjuntiva?
- Mucosal transparent membrane that tapizas the eye from limbo to conjuntival fondos de saco
- Covers sclera = conjuntiva bulbar
- Covers posterior surface of eyelids = palpebral conjuntiva
