Ocular Disease

Vitreous/Retina/Choroid + random

the dark appearance of the fovea in a normal FA image is due to:

• center of fovea does not contain retinal blood vessels (FAZ)

• choroid below fovea does contain a network of blood vessels that fills with fluorescein in the early phase

  • there’s blockage of this background choroidal fluorescence d/t increased density of xanthophyll in foveal region

• background of choroidal fluorescence is blocked d/t RPE cells in fovea, which contain more melanin and are larger than RPE cells elsewhere in retina

what electrodiagnostic test primarily evaluates ganglion cells within the retina?

pattern electroretinogram (pERG)

• ex: POAG

mfERG waveforms represent

photoreceptor and bipolar cell responses

____ evaluates RPE function under dark and light phases

EOG

• responses decrease with dark adaptation and increase with light adaptation

• reduced Arden ratio indicates RPE dysfunction (ex: Best’s)

what disorders result in myogenic blepharoptosis?

• chronic progressive external ophthalmoplegia (CPEO)

• myotonic dystrophy

• myasthenia gravis (MG)

• oculopharyngeal-muscular dystrophy

optic disc drusen vs. optic disc edema

optic disc drusen often lead to → elevation of optic disc edema

• anomalous retinal vascular patterns commonly occur in associated with presence of optic disc drusen

  • may include early vascular branching and increased vessel tortuosity

• vessels coursing optic disc in pts with optic disc drusen are NOT obscured

  • papilledema → do exhibit obscuration of vessels d/t edema of RNFL

• hyperemia of optic disc is associated with papilledema

• 80% of pts with optic disc drusen → (+) SVP

  • loss of SVP = early sign of papilledema

Anton’s syndrome vs. blindsight

Anton’s syndrome: denial of vision loss in patients who are blind

• aka visual anosognosia

• pts act as if their vision is unaffected

blindsight: pts have some visual function but are unaware of it and deny its existence

phacomorphic vs. phacolytic vs. phacoanaphylactic glaucoma

phacomorphic: antero-posterior growth of lens (naturally occurring w age) + natural anterior movement of lens → increase in iridolenticular contact

• can cause pupillary block, iris bombe → increase IOP

phacolytic: proteins leaking into AC thru an intact lens capsule from a hypermature cataract

• obstruct TM → elevate IOP

phacoanaphylactic: autoimmune reaction that occurs secondary to proteins that have leaked from lens with a ruptured capsule

episcleritis is associated with what systemic conditions?

cause is commonly unknown, but can be associated with:

• gout

• herpes zoster

• Crohn’s disease

• syphilis

• mumps

• Lyme

• SLE

• RA

RD most commonly occur between which layers of the retina?

RPE and photoreceptor cell layer

• bc there are no intercellular connections joining the 2 layers

• RPE cells are tightly attached to the choroid

types of plaques that may cause a CRAO?

• calcific plaque: pose the greatest risk of causing CRAO or BRAO

  • very hard, don’t alter in shape or size → impede blood flow and cause ischemia

• hollenhorst plaque: made of cholesterol, commonly dissolve

  • appear larger than the vessel they occupy (bc they’re shiny)

  • lodge transiently at vessel bifurcations

• talc emboli: seen in pts who inject drugs IV

  • don’t pose the greatest risk for CRAO

characteristics of VKH syndrome

systemic autoimmune disease where body attacks melanocytes

• inflammatory response of tissues in body that contain melanocytes (ear, skin, meninges, uveal tissue of eye)

• ocular: ant/post uveitis, non-granulomatous in acute phases

  • bilateral, can lead to RD, CNVM, subretinal fibrosis

most common cause of lens subluxation

1. TRAUMA

2. other etiologies: Marfan’s (up and out), Ehlers-Danlos, Weill-Marchesani, homocystinuria (down and in)

the most common complication after cataract surgery is

posterior capsular opacification (PCO) — 41-51%

• occurs 4-6 months after

• lens epithelial cells migrate to posterior capsule → opacifies

_____ is a rare complication that occurs 2-4 days after cataract surgery that can cause blindness.

endophthalmitis

• s. epidermis = #1 cause

  • s. aureus (catalase +, coagulase +) can also cause it

____ is the most common aging cataract in the embryonic nucleus (n=1.41)

nuclear sclerotic cataract (NSC)

• infant cataracts are also in embryonic nucleus

____ cataract causes a myopic shift

____ cataract causes a hyperopic shift

NSC → myopic shift

• pilocarpine, Diamox, Topamax also cause myopic shift

CC → hyperopic shift

• tumors, IOIS, CME also cause hyperopic shift

absolute contraindications for refractive surgery

• active infection (HSV, corneal warpage)

• keratoconus

• <18 y/o

• unrealistic expectations

• connective tissue disease, collagen vascular disease, immunocompromised

relative contraindications for refractive surgery

• pregnancy

• POAG if uncontrolled

• ocular surface disease, dry eye, bleph, eye rubbing

• diabetes

• retinal thinning or lattice degeneration — consult retinal specialist

diffuse lamellar keratitis (DLK) vs. epithelial ingrowth

DLK: “sands of the sahara”.

• etiology toxins on surgical blade

• 2-3 days post-LASIK

• can cause hyperopic shift (inflammation → stromal tissue melt → flattens cornea)

epithelial ingrowth: white/gray/milky line at flap edge

• 1 month post-LASIK

• most common complication seen with enhancements

characteristics of SMILE

small incision lenticule extraction (SMILE)

• femtosecond laser makes lenticule (not flap) where anterior stroma is mostly intact → less corneal denervation → better biomechanical stability

• candidacy: up to -10.00D and -3.00DC

• best vision in 5-7 days