Szem Flashcards
Shafer’s sign
Suspended pigment particles floating in the anterior vitreous
described as “tobacco dust,”
pathognomonic for a retinal tear
combination of flashing lights and floaters should be considered…
…a retinal detachment until proven otherwise
Finding cotton wool spots in a healthy patient without DM or hypertension…
…consider HIV testing
What antibiotic would you use for a small corneal ulcer in a contact lens wearer?
While most small ulcers can be treated with erythromycin, you must worry about pseudomonas in contact lens wearers. Treat all CL wearers with ciprofloxacin or moxifloxacin. If the ulcer is large, jump right to fortified antibiotics like vancomycin and tobramycin
The major types of penetrating
eye injury are:
eye lid lacerations
corneal lacerations
scleral lacerations
perforating trauma (+/- an exit wound) including occult foreign body penetration (e.g. when metal strikes metal)
There may also be associated injuries to:
intraocular structures — e.g. lens, iris, retina
extraocular structures — e.g. lids, extra-ocular muscles, orbital bones, optic nerve and brain
Marcus-Gunn pupil
Relative afferent pupillary defect
Optic neuritis - papillitis causes
- multiple sclerosis
- familial
- idiopathic
- inflammation
+ viral — e.g. infectious mononucleosis, herpes zoster, viral encephalitis
+ childhood infections or vaccinations — e.g. measles, mumps, chickenpox
+ Granulomatous inflammations — e.g. tuberculosis, syphilis, sarcoidosis, cryptococcus
+ Contiguous inflammation of the meninges, orbit, or sinuses.
What are the Pulfrich phenomenon and Uhthoff sign?
Both of these are occassionally present in optic neuritis:
Pulfrich phenomenon — altered perception of moving objects
Uhthoff sign — worsening of symptoms with exercise or increase in body temperature
Possible underlying causes of papilloedema
- intracranial
space-occupying lesions (e.g. neoplasms, trauma, infection, and vascular causes)
benign intracranial hypertension (trauma, drugs, idiopathic, Addisons, sinus thrombosis)
central venous sinus thrombosis
meningoencephalitis - CSF
hydrocephalus – obstructive, communicating (production vs. absorption of CSF)
high CSF protein — e.g. Guillain-Barre Syndrome - extracranial
central retinal vein occlusion (CRVO)
retro-orbital mass
hypertension (grade IV)
Causes of optic atrophy
Optic atrophy may be the end stage of:
chronic papiloedema chronic optic neuritis glaucoma optic neuropathies (e.g. toxic, metabolic, ischemic and compressive) familial, e.g. retinitis pigmentosa
Compare expected examination findings: optic neuritis and papilloedema
Papillitis (optic neuritis):
pupilary reaction — RAPD present visual acuity — reduced colour vision — red desaturation visual fields — large central scotoma pain on eye movement — present localisation — usually unilateral fundoscopy — blurred disc margins
Papilloedema:
pupilary reaction — normal
visual acuity — normal (transient loss)
colour vision — normal
visual fields — large blind spot, peripheral constriction
pain on eye movement — present
localisation — usually bilateral
fundoscopy — blurred disc margins, no venous pulsation
Oculomotor (III) nerve palsy
The eyes are “down and out” with a droopy eyelid.
The majority of the extraocular muscles are innervated by CN3, so when knocked-out the eye deviates down and out because of the still functioning abducens and superior oblique muscles. In addition, the levator palpebrae (the main lid retractor) is innervated by CN3 and its paralysis gives you a severe eyelid ptosis. Finally, the parasympathetic pupil-constrictor fibers from the Edinger-Westphal nucleus travel within CN3, and their loss gives you a “blown pupil.”
Compressive lesions usually affect the parasympathetic nerve component: a blown pupil is a potential emergency. Whenever you have pupillary involvement, you need an MRI and angiography to rule out a dangerous aneurysm or tumor.
Trochlearis (IV) nerve palsy
- upward deviation of the affected eye
- “cyclotorsion” twisting of the eye -> tilting of the head away from the lesion.
- causes: 1/3rd Trauma
1/3rd Congenital
1/3rd Ischemic (diabetic)
1/3rd Tumor
Abducens paresis (VI)
Crossed eye. Consider increased intracranial pressure.
(Something about this abrupt turn makes the 6th nerve especially susceptible to high intracranial pressure. Patients with high ICP from pseudotumor cerebri commonly have their 6th nerve(s) knocked out – abducens palsy is actually incorporated into the Dandy criteria for diagnosing PTC.)
if the patient has MG, check …
them up for a thymoma and check their thyroid levels
if a patient complains of a painful Horners …
… think of a carotid dissection and move quickly to rule out this diagnosis.
Szem mekkora
Kb. 24 mm átmérőjű, felülről lefelé kb 0.5 mm-el összelapított
Sclera milyen vastag
N. opticus belépése körül 1-2 mm, előrefele folyamatosan vékonyodik, legvékonyabb az equator előtt közvetlenül a szemizmok tapadása mögött ( 0,3 mm), előre újra vastagabb, különösen a szemizmok tapadásának megfelelően (0,6 mm)
Sclerát mik fúrják át
- n. opticus (hátsó pólustól 3 mm medial fele)
- aa. ciliares posteriores breves et longi, nn ciliares breves et longi (n. opticus kilépése körül)
- vv vorticosae (equator tájékán)
- aa ciliares anteriores (szemizmok tapadása tájékán)
Cornea rétegei elölről hátrafele
- Hám (epithelium anterius corneae)
- Lamina limitans anterior (Bowman-hártya)
- Substantia propria corneae
- Lamina limitans posterior (Descemet-hártya)
- Endothelium camerae anterioris
Cornea mérete, vastagsága
13 mm átmérő, kívülről nézve haránt irányban 12 mm, függőlegesen 11 mm
Középen 0,8-0,9 ?! mm, szélein 1,1 mm
M. ciliaris részei kívülről befele
- medialis irányú rostok (Brücke-féle izom)
- radialis irányú rostok
- circularis irányú rostok
Iris rétegei elölről hátra
- Endothelium
- Stroma iridis
- M. dilatator pupillae
- Stratum pigmenti iridis = pars iridica retinae
Choroidea rétegei kívülről befele
- Lamina suprachoroidea
- Lamina vasculosa
- Lamina chorocapillaris
- Lamina basalis (Bruch féle hártya)
Tunica vasculosa erei
- aa ciliares posteriores breves -> sp. perichoroidale -> oszlik a choroideában és a corpus ciliare hátsó részében -> vv vorticosae
- aa ciliares posteriores longi (nas et temp) -> sp. perichoroidale -> corpus ciliare és iris határán kettéoszolva egymással anast -> circulus arteriosus iridis major [~iris külső + c ciliare elülső] {+ aa ciliares anteriores}
- circulus arteriosus iridis minor [~ iris belső] 1. Orbiculus ciliaris meridonalis erei -> chiroidea venái 2. Corneoscleralis határ -> episcleralis venahálózat
Tunica vasculosa idegei
- nn ciliares breves {psy rostok ggl ciliaréból + sy postgangl rostok gg cercicale superius}
- nn ciliares longi {n nasociliarisból leváló somatosensoros ágak}
Belépés->sp. perichoroidale -> c ciliare: sűrű fonat -> leváló ágak:
+ tisztán érző: szaruhártyában l propriát es elülső hámréteget
+ psy postggl: c ciliarehoz, m ciliarist idegzik be
+ érző és vegetatív motoros rostokat tart ágak -> iris ->
> m sphincter pupillae (ggl ciliareból postggl)
> m dilatator pupillae (ggl cervicale superiorból postggl)
> stroma (n nasociliarishoz tartozó érzőrostok)
Retina fejlődéstanilag miből alakult ki
Prosencephalon -> diencephalon
Retina milyen vastag
Hátul 0,4 mm, ora serrata közelében 0,1 mm
Vakfolt mérete
1,6 mm
Sárgafolt mérete, helye
Discus nevinopticu közepétől lateral fele 4 mm-re (kb 15fok), 2mm átmérőjű ellipsis
Retina erei
A et v centralis retinae -> a et v papillaris superior et inferior -> arteriola et venula temporalis retinae superior, temporalis retinae inferior, nasalis retinae superior, nasalis retinae inferior
Macula luteához: arteriola et venula macularis superior et inferior
Retina rétegei
Szemgolyó központjára vonatakoztatva
- Pigmenthám (str pigmenti retinae)
- Csapok és pálcikák
- Membrana limitans externa
- Str granulosum externum
- Str plexiforme externum
- Str granulosum internum
- Str plexiforme internum
- Str ganglionare
- Opticusrostok rétege
- Membrana limitans interna
Seidel test corneal laceration
Wipe a strip of fluorescein paper over the wound, if the dye flows down the corneal surface -> aqueous leakage
Converting Cylinder
You can convert a glass prescription from +/- cylinder format by the following method:
a. add the cylinder to the sphere (you remember how to add negatives, don’t you?)
b. change the sign of the cylinder
c. change the axis by 90 degrees
Thus: +2.00 +3.00 at 170 converts to
+5.00 –3.00 at 080
Szemlencse alakja, mérete
Bikonvex lencséhez hasonló, facies anterior laposabb, facies posterior domborúbb, 9 mm átmérő
Újszülöttön majdnem gömb alakú, d=4,5 mm
Csarnokvíz összetevői
Kevés fehérje, szőlőcukor, karbamid, hialuronsav
