ophthamology - orbit Flashcards
What is the osteology of the orbit?
7 PAIRED BONES
THE ORBITAL RIM
Maxillary bone Zygomatic bone Frontal bone
THE INTERNAL ORBIT
Sphenoid Ethmoid Lacrimal Palatine
What are the visceral structures in the orbit?
EYE
MUSCLES
RECTUS (4)
OBLIQUES (2)
EYELID (1)
NERVES
BLOOD VESSELS LACRIMAL SYSTEM FAT
What are the nerves associated with the orbit?
OPTIC N
(cranial nerves) OCULOMOTOR TROCHLEAR ABDUCENS
TRIGEMINAL V
V1 V2
SYMPATHETIC PARASYMPATHETIC (nasociliary, frontal, lacrimal)
what are the arteries associated with the orbit?
OPHTHALMIC ARTERY (ICA)
CENTRAL RETINAL ARTERY
INFRAORBITAL ARTERY (MAXILLARY - ECA)
FACIAL ARTERY OPHTHALMIC VEIN
what are the different orbit fractures?
INTERNAL:
*FLOOR, MEDIAL WALL, ROOF, LATERAL WALL
EXTERNAL:
*NOE, ZMC, LEFORT,
- NOE - The nasoorbitoethmoid (NOE) complex is the confluence of the frontal sinus, ethmoid sinuses, anterior cranial fossa, orbits, frontal bone, and nasal bones. The intricate anatomy of this area makes NOE injuries one of the most challenging areas of facial reconstruction
- ZMC - The zygomaticomaxillary complex (ZMC) plays a key role in the structure, function, and aesthetic appearance of the facial skeleton. It provides normal cheek contour and separates the orbital contents from the temporal fossa and the maxillary sinus.
- lefort - Le Fort fractures are fractures of the midface, which collectively involve separation of all or a portion of the midface from the skull base. In order to be separated from the skull base the pterygoid plates of the sphenoid bone need to be involved as these connect the midface to the sphenoid bone dorsally. The Le Fort classification system attempts to distinguish according to the plane of injury.
What is an NOE fracture?
*NOE - The nasoorbitoethmoid (NOE) complex is the confluence of the frontal sinus, ethmoid sinuses, anterior cranial fossa, orbits, frontal bone, and nasal bones. The intricate anatomy of this area makes NOE injuries one of the most challenging areas of facial reconstruction
what is a ZMC fracture?
*ZMC - The zygomaticomaxillary complex (ZMC) plays a key role in the structure, function, and aesthetic appearance of the facial skeleton. It provides normal cheek contour and separates the orbital contents from the temporal fossa and the maxillary sinus.
what is a lefort fracture?
*lefort - Le Fort fractures are fractures of the midface, which collectively involve separation of all or a portion of the midface from the skull base. In order to be separated from the skull base the pterygoid plates of the sphenoid bone need to be involved as these connect the midface to the sphenoid bone dorsally. The Le Fort classification system attempts to distinguish according to the plane of injury.
A punch straight to the eye will cause what kind of fracture?
- BUCKLE (ROOF FX IN KIDS)
* BLOW OUT (FLOOR ADULTS)
what are the signs of orbital fracture?
PAIN, ECCHYMOSIS, EDEMA, PROPTOSIS, ENOPHTHALMOS, EMPHYSEMA, NAUSEA/ VOMITING, BRADYCARDIA, DIPLOPIA
- proptosis - Proptosis is protrusion of the eyeball. Exophthalmos means the same thing, and this term is usually used when describing proptosis due to Graves disease. Disorders that may cause changes in the appearance of the face and eyes that resemble proptosis but are not include hyperthyroidism without infiltrative eye disease, Cushing disease, and severe obesity
- diplopia - subjective complaint of double vision
- ecchymosis - discoloration of skin, usually bruising
and orbital floor fracture can result in entrapment, the signs of which are…?
ORBITAL FLOOR FX
- ENOPHTHALMOS - Enophthalmos is the posterior displacement of the eyeball within the orbit due to changes in the volume of the orbit (bone) relative to its contents (the eyeball and orbital fat), or loss of function of the orbitalis muscle.
- HYPOGLOBUS - Hypoglobus following orbital decompression is not a rare complication. Hypoglobus requiring surgery to elevate the globe following orbital decompression is considered clinically significant hypoglobus.
Swelling of the tissue around the orbit can be indicative of auto-immune disease how?
PRIMARY INFLAMMATORY DISEASE OF THE ORBITAL SOFT TISSUE AUTO-IMMUNE DISEASE (TARGET IS THE ORBITAL FIBROBLAST)
ASSOCIATED WITH AUTO-IMMUNE THYROID DISEASE (MOST COMMONLY GRAVES DISEASE) DYSTHYROIDISM IS NOT THE CAUSE
Describe the mechanism behind the eye protruding in thyroid disease
THE ORBITAL FIBROBLAST HAS EXPRESSES TSH-R & ILGF-R
STIMULATORY AUTO-ANTIBODIES (TSI) STIMULATE ORBITAL FIBROBLAST TO PRODUCE PRO-INFLAMMATORY CYTOKINES AND RECUIT INFLAMMATORY CELLS INTO ORBITAL SOFT TISSUE
LEADS TO PRODUCTION OF HYALURONAN [GLYCOSANIMOGLYCAN (GAG)]
LYMPHOCYTIC INFILTRATION, GAG PRODUCTION, AND ORBITAL FIBROBLAST PROLIFERATION (ADIPOGENESIS) CAUSES EOM HYPERTROPHY
describe the treatments of EOM hypertrophy in thyroid disease
one treatment is immunomodulators during the active phase of the disease
*surgical intervention is indicated during the quiescent phase of the disease
90% of eyelid skin cancer is due to what?
Basal cell carcinoma *90% OF EYELID SKIN CA COMMONLY INVOLVES LOWER EYELID TREATMENT IS EXCISION WITH MARGIN CONTROL (FROZENS OR MOHS) RECONSTRUCTION
what are the different parts of the lacrimal drain?
LACRIMAL DRAIN: PUNCTUM, CANALICULUS, LACRIMAL SAC, LACRIMAL DUCT
what is meant by nldo?
*nasolacrimal duct obstruction
BLOCKAGE IN LACRIMAL DUCT (BELOW LACRIMAL SAC)
NLDO might cause Epiphora why?
Epiphora is an overflow of tears onto the face. A clinical sign or condition that constitutes insufficient tear film drainage from the eyes in that tears will drain down the face rather than through the nasolacrimal system
What is CHRONIC DACRYOCYSTITS
CHRONIC DACRYOCYSTITS - cyst in the lacrimal drainage pathway. Requires hospitilization and IV antibiotics (acute) can be a reason for chronic overtearing and epiphora
DCR is the treatment for acute dacryocystitis. what is it?
DCR - DACRYOCYSTORHINOSTOMY, get in there and surgically drain that puppy and remove the offending cyst
*put in a silicone stent to keep the fluid moving
What are the Layers of posterior eye wall?
a. Sclera – outer layer, white fibrous
b. Choroid – middle layer, vascular supply
c. Retina – inner layer, photosensitive tissue
What are the two parts of the macula?
Macula - 6mm, central vision
a. Fovea – 1.5 mm, avascular, cones
b. Foveola – No ganglion cells, just photoreceptors
What are the three divisions of the retina?
- Macula – 6mm, central vision
a. Fovea – 1.5 mm, avascular, cones
b. Foveola – No ganglion cells, just photoreceptors
2. Equatorial retina – mainly rods, peripheral vision
3. Peripheral retina
a. Ora serrata
b. Pars plana (posterior ciliary body)
the neurosensory retina is composed of what cells?
a. Photoreceptors
i. Rods – Night/peripheral vision
ii. Cones – Central/color vision
b. Support cells – bipolar and other glial cells
c. Ganglion cells – long axons that form optic nerve
What is the retinal pigment epithelium?
- Photoreceptor metabolism
- Outer blood-retina barrier
- Potential space – retinal detachment if fluid accumulates
What is the important vasculature of the retina?
- Central Retinal Artery
a. Branch of ophthalmic artery, from internal carotid artery
b. Inner 2/3 of retina
2. Central Retinal Vein
3. Capillaries – inner blood-retina barrier
What is the differential diagnosis of a retina that looks red?
a. Subretinal hemorrhage – dark red blood underneath retina
b. Intraretinal dot-blot hemorrhage – circular hemorrhage in middle retina
c. Flame hemorrhage – linear hemorrhage in nerve fiber layer
d. Pre-retinal hemorrhage – ‘boat shaped’ hemorrhage in front of retina
e. Vitreous hemorrhage – hemorrhage in vitreous cavity
What is the differential diagnosis of a retina that looks yellow?
a. Hard exudate – lipid/cholesterol deposits, diabetes and vascular disease
b. Drusen – round, yellow subretinal deposits, macular degeneration
c. Hollenhorst plaque – cholesterol embolus in blood vessel
What might cause the retina to look white?
a. Cotton wool spot – fluffy white, capillary ischemia, diabetes and HTN
b. Branch retinal artery occlusion – sectoral infarction of branch artery
what might cause the retina to appear brown?
a. Choroidal nevus – circumscribed pigmented nevus
b. Macular or retinal scar – from injury/degeneration/or inflammation
What is the #1 cause of blindness in working age adults in the US?
Diabetic retinopathy
what are the risk factors for diabetic retinopathy?
Risk factors
i. Duration of diabetes – 50% at 10 yrs, 90% at 30 yrs
ii. Glycemic control
iii. Blood pressure
iv. Pregnancy
What are the contributing factors to the pathophysiology of diabetic retinopathy?
Pathophysiology
i. Microvascular injury ii. Hemorrhage iii. Leakage iv. Ischemia v. Neovascularization
what is non-proliferative diabetic retinopathy?
Non-Proliferative Diabetic Retinopathy (NPDR)
i. Microaneurysms, flame hemorrhage, dot-blot hemorrhage ii. Macular edema – #1 cause of vision loss in DM iii. Hard exudates – lipoprotein
What is Proliferative Diabetic Retinopathy (PDR)?
Proliferative Diabetic Retinopathy (PDR)
i. 5-10% of DM, up to 60% of Type 1 DM after 30 yrs of disease
ii. Neovascularization – optic disc and retina
iii. Vitreous hemorrhage
iv. Tractional retinal detachment
v. Neovascularization of iris → Neovascular glaucoma
How do you manage diabetic retinopathy?
1) Glycemic and BP contro
ii. Screening eye exams
iii. Laser photocoagulation
a. Diabetic macular edema – Focal laser
b. PDR – Panretinal photocoagulation
iv. Anti-Vascular Endothelial Growth Factor (VEGF) injections
a. Monoclonal antibodies injected intravitreally
b. Originally for colon cancer
c. Improve diabetic macular edema
v. Pars Plana Vitrectomy
a. Vitreous hemorrhage
b. Tractional retinal detachment
What’s up with hypertensive retinopathy?
a. Vasoconstriction – arteriole narrowing
b. Arteriosclerosis – copper and silver wiring, arterio-venous nicking
c. Hemorrhage
d. Edema and exudate
e. Optic disc edema – esp. with acute, severe HTN
what are the signs of the two major retinal vascular occlusions?
a. Central retinal vein occlusion – extensive retinal hemorrhage and edema
b. Central retinal artery occlusion – cherry red spot
what are the age related macular degeneration risk factors?
i. Age – 6% age 65-74, 20% ≥75 yrs
ii. Race – Caucasians
iii. Gender – females
iv. Tobacco smoking
What is dry AMD?
b. Dry AMD
i. Drusen – lipoprotein deposits
ii. RPE changes – atrophy and hyperpigmentation
iii. Geographic atrophy – severe vision loss if in fovea
iv. Antioxidant vitamins prevent progression in high risk eyes
what is wet AMD?
Wet AMD – more vision loss, less common, ~10% of AMD
i. Choroidal neovascularization (CNV) ii. Macular edema and hemorrhage iii. Fibrotic disciform scar – end-stage iv. Anti-VEGF intravitreal injections a. First treatment to improve vision in wet AMD b. Regression of CNV c. Improved macular edema
what is the ora serrata?
The ora serrata is the serrated junction between the retina and the ciliary body. This junction marks the transition from the simple non-photosensitive area of the retina to the complex, multi-layered photosensitive region.
what’s important to know about the vascular layer of the choroid?
B. Vascular layer
1. Highest blood flow per tissue weight 2. Between retina and sclera 3. Metabolic support 4. Heat sink for RPE
what are the important pathological conditions affecting the choroid to keep in mind?
- Uveitis – inflammation of the choroid/uveal tissue
2. Choroidal nevus
3. Tumors
what is the vasculature that supplies the optic nerve?
- Posterior ciliary artery branches to optic disc
2. Pial capillaries from ophthalmic artery
What is the most common cause of optic neuropathy?
. Glaucoma – Most common optic neuropathy
a. Damage to nerve fiber layer and optic disc resulting in visual field loss
what are the risk factors for glaucoma?
Risk factors
i. Age ii. Elevated intraocular pressure (IOP) iii. Race iv. Central corneal thickness v. Family history vi. Myopia (nearsightedness)
what are the different classificaitons of glaucoma?
i. Primary vs secondary
ii. Acute vs chronic
iii. Open vs closed angle
what are the exam findings that point to glaucoma?
i. Elevated IOP – but 15% normal IOP
ii. Enlarged C/D or asymmetry
iii. Optic disc hemorrhage
iv. Visual field defects
how do you manage glaucoma?
i. Screening – asymptomatic until end-stage
ii. Lower IOP
a. Medications – decrease aqueous or increase outflow
b. Laser
c. Surgery – with or without drainage implants
what is papilledema and why is it alarming?
- Papilledema
a. bilateral optic disc swelling due to elevated ICP
b. blurring of disc margin, sometimes flame hemorrhage on margin
