Ophthalmology Flashcards
(47 cards)
1
Q
Eyelids
A
- Protects the cornea
- Tarsal plates ⇒ dense CT plates
- Movement controlled by orbicularis oculi muscle (CN VII)
2
Q
Tear Film
A
- Tear film consists of aqueous, mucin, and lipid components
-
Meibomian glands and glands of Zeis produce lipid for tear film
- Blockage and inflammation of glands can cause a “stye”
- Lacrimal gland produces aqueous component
-
Lacrimal drainage system drains into nasal cavity
- Canaliculi ⇒ nasolacrimal sac ⇒ nasolacrimal duct ⇒ nasal cavity
3
Q
Extraocular Muscles
A
- Four rectus muscles ⇒ superior, inferior, medial, lateral
- Two oblique muscles ⇒ superior and inferior
-
All controlled by oculomotor nerve (CN III) except for:
- Superior oblique ⇒ trochlear nerve/CN IV
- Lateral rectus ⇒ abducens nerve/CN VI
4
Q
Conjunctiva
A
Clear tissue overlying the sclera and lining the inner surfaces of the eyelids
5
Q
Cornea
A
Clear collagenous structure
Provides ⅔ of the eye’s refractive power
-
Composed of 3 cell layers:
- Surface epithelium with underlying Bowman layer
-
Stroma ⇒ keratocytes and collagen fibrils
- Middle and largest layer
-
Endothelium ⇒ single cell layer on inner surface of cornea
- Makes Descemet’s membrane (true basement membrane)
-
Must remain optically clear:
- Endothelial Na+/K+ pump and carbonic anhydrase ⇒ maintain dehydration of cornea
- Corneal edema reduces optical clarity
- Eyelid and lacrimal system protect and lubricate the cornea
6
Q
Layers of the Globe
A
Sclera, Uvea, Retina
7
Q
Sclera
A
- Outer white collagenous layer
- Covers posterior 4/5 of globe
- Anterior opening for cornea
- Posterior opening for optic nerve
8
Q
Uvea
A
- Middle vascular layer
- Provides blood flow to ocular structures
- Anterior eye ⇒ Iris and ciliary body
- Posterior eye ⇒ Choroid
9
Q
Retina
A
Neurosensory layer
- Where light perceived and translated to neuronal signals
- Composed of neural, glial, and vascular elements
- Light ⇒ photochemical rxn in rods and cones
- Visual cascade from photoreceptor cells to ganglion cells
- Axons of ganglion cells form retinal nerve fiber layer ⇒ becomes the optic nerve
- Macula ⇒ central area of the retina encircled by vascular arcades
-
Fovea ⇒ area of macula with primarily cone photoreceptors
- Higest visual acuity and fine discrimination
10
Q
Anterior Chamber
A
- Contains aqueous humor produced by ciliary body
-
Trabecular meshwork
- In anterior chamber “angle”
- Drains aqueous fluid
- Blockage or reduced function ⇒ ↑ intraocular pressure and glaucoma
- Visualized with gonioscopy
11
Q
Crystalline Lens
A
- Optically clear structure
- Provides ~ 1/3 of refractive power of the eye
- Suspended behind iris by zonular fibers
12
Q
Posterior Segment
A
Structures posterior to lens
Includes vitreous body, retina, choroid, optic nerve
- Vitreous humor ⇒ gel=like substance that fills that back of the globe
-
Optic nerve ⇒ carries neurosensory signals from retina to brain
- Exits back of the eye at the optic disc
- Causes physiologic blind spot
- Exits back of the eye at the optic disc
13
Q
Refractive Error
A
Caused by light being focused in front of or behind the retina
Refractive power of eye comes from tear film, cornea, and lens
14
Q
Myopia
A
When light is focused in front of the retina
Corrected by “minus” or divergent/concave lens
15
Q
Hyperopia
A
When light is focused behind the retina
Corrected by “plus” or convergent/convex lens
16
Q
Astigmatism
A
When eye is ovoid
Light focuses in two planes instead of one point
17
Q
Chronic Conditions
A
- Cataracts
- Diabetic retinopathy
- Primary open angle glaucoma
- Age-related macular degeneration
18
Q
Cataract
A
Clouding of crystalline lens
- Caused by age, medications (corticosteroids), diabetes, trauma, congenital
- Results in reduced best-corrected visual acuity and/or glare
- Treatment is cataract extraction with intraocular lens implantation
19
Q
Diabetic Retinopathy
A
Caused by microvascular damage due to elevated blood glucose
-
Non-proliferative/Background DR:
- Dot-blot hemorrhages
- Microaneurysms
- Hard exudates
- Cotton wool spots
- May have macular edema
-
Proliferative DR:
- Retinal neovascularization
- Caused by prolonged ischemia and VEGF release
- Abnormal vessels can bleed ⇒ retinal or vitreous hemorrhage & retinal detachment
- Retinal neovascularization
-
Treatment:
- Blood glucose control
- Laser (panretinal photocoagulation)
- Iintravitreal injections of anti-VEGF medications
- Surgery
20
Q
Primary Open Angle Glaucoma
A
Progressive damage of retinal nerve fiber layer
- Usually associated with ↑ intraocular pressure
- ↑ “cup-to-disc ratio” on optic nerve exam
- Results in loss of peripheral vision & eventually blindness
- ↑ risk in African American population & those with a family history
-
Treated with laser, surgery, or medications to lower intraocular pressure
- β-blockers ⇒ ↓ production of aqueous humor @ ciliary body
- α2-selective agonists ⇒ ↓ production of aqueous humor & ↑ outflow via uveosclera pathway
- Carbonic anhydrase inhibitors ⇒ ↓ production of aqueous humor @ ciliary body
- Prostaglandin analogues ⇒ ↑ outflow via uveosclera pathway
- Cholineric agents ⇒ induce miosis & ↑ outflow via trabecular meshwork
21
Q
Age-related Macular Degeneration
(AMD)
A
Degeneration of outer retinal layers in macula
-
Dry AMD:
- Deposition of degenerative material in yellow spots called “drusen” in Bruch’s membrane
- Atrophy of retinal pigment epithelium and photoreceptor cells dt abnormal choriocapillaris layer
- Results in ↓ visual acuity, color vision, contrast sensitivity
- No treatment, more preventative
- AREDS vitamins may reduce risk of progression
- Monitor with Amsler grid for progression to wet AMD
-
Wet AMD:
- Choroidal neovascularization that breaks through Bruch’s membrane
- Causes edema, hemorrhage and scarring of retina and subretinal space
- Treated with intravitreal injections of anti-VEGF medications
22
Q
Acute Conditions
A
-
Traumatic/Toxic:
- Corneal abrasion and Infectious keratitis
- Subconjunctival hemorrhage
- Hyphema
- Chemical injury
- Eyelid laceration
- Open globe injury
-
Other acute conditions:
- Conjunctivitis
- Central retinal artery occlusion
- Central rretinal vein occlusion
- Acute angle closure glaucoma
- Retinal detachment
23
Q
Corneal Abrasion
A
Defect in epithelial layer of cornea
- Sx include acute-onset pain, photophobia, tearing and redness
- Dx by fluorescein stain with cobalt blue light
- Cornea re-epithelializes within days
- Tx is supportive
- Abx prophylaxis if large abrasion or dirty mechanism of injury
24
Q
Infectious Keratitis
A
“Corneal ulcer”
Microbial infection of corneal stroma with overlying epithelial defect
- Sx include pain, photophobia, red eye
- Often occurs post-trauma
- High risk in contact lens wearers with poor hygiene practices
- Risk of corneal thinning and perforation
- Requires culture, aggressive abx therapy, and monitoring by ophthalmologist
25
Subconjunctival Hemorrhage
**Hemorrhage accumulating between sclera and conjunctiva**
* May be due to Valsalva maneuver, coagulopathy, systemic conditions like DM or HTN, trauma, or idiopathic
* Requires eye exam to r/o other etiology
* Supportive tx only for simple subconjunctival hemorrhage
26
Hyphema
**Hemorrhage in anterior chamber of eye**
* May be due to trauma, coagulopathy, neovascularization of the iris or angle, and anterior segment tumors
* Requires evaluation and treatment with ophthalmologist
* Patients with sickle cell disease have higher risk of secondary glaucoma and re-bleed
27
Chemical Injury
* **Ophthalmic emergency** ⇒ requires immediate irrigation of chemical from the eye
* **Acid injuries**
* Causes coagulation necrosis
* Less risk of corneal perforation
* **Alkali injuries**
* Causes saponification necrosis
* Can rapidly lead to corneal perforation
* Both can result in **anterior segment ischemia, corneal scarring/opacification, glaucoma, and other blinding conditions**
28
Eyelid Laceration
Simple lacs can be repaired at the bedside
Complex cases involving canaliculus or orbital septum require OR repair
29
Open Globe Injury
* May be subtle
* Peaked pupil, iris, or uveal prolapse from laceration
* **Ophthalmic emergency requiring repair in operating room**
* **High risk of infectious endophthalmitis**
* Treat with IV abx
* Rule out intraocular or orbital foreign body
* History (mechanism of injury) is crucial
* Imaging can be helpful (CT scan or X-ray, not MRI if suspect metallic FB)
30
Conjunctivitis
Overview
**Inflammation of the conjunctiva resulting in redness, tearing and/or mucous discharge, and mild discomfort.**
Bacterial, viral, and allergic causes.
31
Bacterial
Conjunctivitis
* Usually more purulent and unilateral
* May have hx consistent with source of inoculation
* Tx with topical abx
32
Viral
Conjunctivitis
* May have hx of viral prodrome
* More often bilateral
* Usually more watery and occasionally itchy
* No abx indicated
33
Allergic
Conjunctivitis
* Prominent itching and watering
* Tx is avoidance of allergen, topical antihistamines and anti-allergy medications
34
Gonococcal
Conjunctivitis
_Special case of bacterial conjunctivitis:_
* Hyperacute, severe purulent discharge
* Risk of corneal involvement with perforation within 24 hours
* Requires ophthalmic consult, systemic treatment with ceftriaxone and concurrent treatment for chlamydia (azithromycin)
35
Central Retinal Artery Occlusion
| (CRAO)
**Acute blockage of central retinal artery** ⇒ acute ischemia of retina ⇒ “stroke of the eye”
* Often d/t an embolus
* **Causes diffuse retinal pallor except at fovea** ⇒ “**cherry red spot**” on fundus exam
* Usually results in severe vision loss
* No treatment ⇒ poor prognosis
* Systemic workup for etiology of embolus (ECHO, carotid studies, hypercoagulable work-up)
36
Central Retinal Vein Occlusion
| (CRVO)
* **Often caused by compression of central retinal vein at optic nerve d/t HTN or anatomy**
* _Fundoscopic findings:_
* **“Blood and thunder” fundus**
* **Dilated and tortuous vessels**
* **± Macular edema**
* _Clincal manifestations:_
* **Acute vision loss**, usu. worse if severe macular edema or severe retinal ischemia
* Severe ischemia ⇒ ± neovascularization of retina/iris ⇒ **neovascular glaucoma**
* _Treatment:_
* **No acute treatment**
* **Chronic treatment with laser and/or anti-VEGF injections** to treat neovascularization
37
Acute Angle Closure Glaucoma
**Acute rise in intraocular pressure caused by occlusion of outflow pathways for aqueous humor in the anterior chamber**
* Very elevated intraocular pressure (40-60)
* Can result in **optic neuropathy and blindness in hours** if untreated
* _Clinical manifestations:_
* Acute-onset severe eye pain and redness
* Blurred vision with rainbows or haloes around lights
* Headache
* ± Nausea/vomiting
* _Exam findings:_
* **Fixed mid-dilated pupil**
* **Conjunctival injection**
* **Corneal edema/haze**
* **Closed angle on gonioscopy**
* Requires urgent lowering of IOP with medications and ultimately usually requires laser iridotomy
38
Retinal Detachment
**Separation of retinal layer from underlying choroidal layer**
* Most common type is **rhegmatogenous retinal detachment**
* Caused by tear or hole in retina that allows fluid to separate retina from choroid
* Signs/symptoms include **floaters, flashing lights, curtain/veil over vision**
* Dx with B-scan US and dilated fundus exam
* Visual acuity depends on whether macula is attached or detached:
* **Macula-on RD** (good vision) ⇒ requires emergent surgical repair
* **Macula-off RD** ⇒ requires urgent but not emergent repair
* Retinal tear/hole may require barrier laser to prevent RD
39
Hypertensive Retinopathy
**Retinal vascular changes due to elevated blood pressure**
Thickening of arteriolar walls ⇒ **copper wiring and silver wiring**
_Grading system:_
* **Grade I:** Arteriolar attenuation
* **Grade II:** A-V nicking
* **Grade III:** Flame-shaped retinal hemorrhages, cotton wool spots, retinal exudates
* **Grade IV:** Above + optic disc edema
40
Uveitis
Inflammation of the uveal tissue
May be due to systemic inflammatory/autoimmune conditions or infections.
* **Anterior uveitis**: iritis or iridocyclitis
* Sx include pain, red eye, photophobia, ± blurred vision
* May see synechiae of iris to lens or keratic precipitates (white spots on back of cornea)
* Requires slit lamp dx by visualization of WBCs in anterior chamber aqueous humor
* **Posterior uveitis**: choroid/vitreous involvement
* Less specific symptoms
* May have floaters and blurred vision
* _Multiple etiologies including:_
* **Systemic inflammatory diseases**
* SLE, sarcoidosis, rheumatoid arthritis, inflammatory bowel disease, Behcet disease
* **Infections**
* Syphilis, Lyme disease, CMV, herpetic infections, tuberculosis
* Treated with topical steroids ± systemic treatment for underlying etiology
41
Papilledema
**Optic disc edema secondary to ↑ intracranial pressure**
* _Etiologies:_ tumors, hydrocephalus, pseudotumor cerebri, ICH, AV malformations, brain abscess, encephalitis, cerebral venous sinus thrombosis
* **May have headache, transient vision obscurations** (position-dependent)
* Esp. when returing to upright position from laying flat
* _Fundoscopic findings:_
* Optic nerve head is elevated and hyperemic
* Disc margins blurred
* May see hemorrhages on or around the disc
* Treat underlying etiology
42
Optic Neuritis
**Acute optic nerve inflammation often associated with multiple sclerosis**
* Unilateral reduced vision, reduced color vision, pain with extraocular movements
* Optic nerve appearance normal in 2/3 of cases
* Pulse-dose IV steroids over three days with PO taper
* MRI recommended especially if no prior diagnosis of MS
* Can help assess risk of progression to MS over time
* Vision usually recovers over 4-6 weeks
43
Arteritic Ischemic Optic Neuropathy (AION)
or
Giant Cell Arteritis (GCA)
Giant cell or temporal arteritis ⇒ **± inflammation in ophthalmic artery and ischemia of optic nerve** ⇒ sudden vision loss
* _Presentation:_
* Usually patients over 55,
* Severely reduced visual acuity
* Jaw claudication, tenderness of scalp over temporal artery
* May have symptoms of polymyalgia rheumatica
* **Check ESR, CRP, platelets** ⇒ will all be elevated in GCA/AION
* **Tx w/ Pulse dose IV steroids** with PO taper
* Critical to prevent involvement of contralateral eye
* **Temporal artery biopsy for diagnosis** (granulomatous inflammation) – do not delay treatment for biopsy!
44
HIV-Related Conditions
* **HIV Retinopathy:**
* Retinal hemorrhage, microaneurysms, cotton wool spots (microangiopathy)
* **CMV retinitis:**
* “Pizza pie fundus”
* Treated with IV ganciclovir or foscarnet
* May do intravitreal ganciclovir
* Risk higher when CD4 count is ≤ 50
* **Progressive Outer Retinal Necrosis (PORN):**
* Herpes virus-related retinal inflammation and necrosis
* Requires IV antiviral (acyclovir) treatment
* High risk of retinal detachment
* **Other infectious retinochoroiditis:**
* Toxoplasma gondii, pneumocystis jirovecii, Cryptococcus neoformans, syphilis
* **Tumors:**
* Kaposi sarcoma of conjunctiva or eyelid
* Intraocular or periocular lymphoma
* Conjunctival squamous cell carcinoma
45
Acute Conjunctival Injection
Differentials
* _Pupils as a clue:_
* **PERRL** ⇒ conjunctivitis, corneal abrasion or keratitis, subconjunctival hemorrhage
* **Small pupil that does not react normally** ⇒ suspect acute ritis or anterior uveitis
* **Large pupil that does not react normally** ⇒ suspect acute angle closure glaucoma
* _Symptoms as a clue:_
* **Pain and/or photophobia** ⇒ corneal abrasion or keratitis, acute iritis/uveitis, acute angle closure galucoma
* **Painless** ⇒ most types of conjunctivitis, subconjunctival hemorrhage
46
Uveal Melanoma
* **Most common primary intraocular tumor in adults**
* **May occur at iris, ciliary body, choroid**
* Choroidal melanoma ⇒ ± mushroom configuration if breaks through Bruch’s membrane
* Spindle cell has best prognosis, epithelioid worst prognosis
* **Propensity for hematogenous metastasis to liver**
* Treatment may include radiation, plaque brachytherapy, enucleation, others
47
Retinoblastoma
* **Most common primary intraocular malignant tumor in children**
* Usually dx at age 3 or younger
* **RB1 tumor suppressor gene mutation** – “two-hit” hypothesis
* Germline mutation results in bilateral disease
* 45% of offspring affected
* **95% of cases are sporadic mutations**
* Symptoms include **leukocoria, strabismus, reduced vision**
* _Risk of metastasis low if does not extend outside the eye_
* May invade **optic nerve, orbit, brain**
* Metastatic sites usually include **bones, central nervous system, lymph nodes, abdominal viscera**
* _Treatment:_ chemo, radiation; enucleation is definitive therapy for tumors without extraocular extension
* Good prognosis in developed countries (95% survival rates)
* Patients with bilateral disease have higher risk of certain extraocular tumors later in life
