1 Flashcards
different visual acuity notations
- US notation:20/40 (standard 20/20)
- 6 meter notation:6/12
- Decimal notation: 0.50
- MAR (MAgnification Requirement ): 2.0
- logMAR: 0.3 (standard 0.0: [+0.1]=[-1 line on chart )
- VAS(Visual Acuity Score): 85 (standard 100 points)
OCT stands for
Optical coherence tomography
The most common early to mid stage glaucomatous field.
Superior / Inferior Arcuate Defect
Severe Constriction with a Central Island visual field indicates
end stage glaucoma
Legal blindness is defined as
central visual acuity of 20/200 or worse in the better-seeing eye with best correction or a visual field of 20 degrees or less.
4 major causes of severe vision loss and blindness in older adults
- age-related macular degeneration (AMD),
- ocular complications of DM,
- glaucoma,
- age-related cataracts
Amsler Grid is used to
test macular function or to detect a central or paracentral scotoma
LASIK stands for
Laser-assisted in-situ keratomileusis (Refractive Eye Surgery)
Describe corneal layers
- Stratified Squamous epitheliem
- Bowman’s membrane
- Stroma
- Descemet’s membrane
- Endothelium
Anterior Chamber Angle is formed by
the posterior corneal surface and the anterior surface of the iris
Normal angle structure seen in Gonioscopy (posterior to anterior approach)
“ICSTS”
- Iris
- Ciliary body band (CB)
- Scleral spur (SS)
- Pigmented Trabecular Meshwork (TM)
- Non-Pigmented Trabecular Meshwork (TM)
- Schwalbe’s line (SL)
- Posterior corneal surface
what is Seidel Test?
A test to detect a wound leak. [If a perforation and leak exist, the dark orange (concentrated) fluorescein dye is diluted by the aqueous and appears as a green (dilute) stream seen with the cobalt blue light of the slit lamp.]
A diopter
the power of a lens to properly focus light on a person’s retina—>defined as “the inverse of a person’s focal length in metres.”
-myopia
+hyperopia
normal range of Intraocular pressure (IOP)
10 to 21 mm Hg
normal aqueous humor outflow routes
- trabecular meshwork (most)
3. uveoscleral routes —->suprachoroidal space
two most common forms of glaucoma
- primary open-angle glaucoma (POAG)
2. primary angle-closure glaucoma (PACG)
Pathophysiology of glaucoma
- POAG:Outflow pathways is diminished.
- PACG: Abnormally positioned iris
the typical disease course of glaucoma left untreated
asx(chronic, progressive, and irreversible visual field loss)—> tunnel vision—>loss of central vision.
Glaucoma medications
Goal: ↓IOP
- Decreases inflow:
1. Beta-blockers
2. Selective α2-receptor agonists
3. Topical carbonic anhydrase inhibitors (CAIs) - Increases outflow:
1. Prostaglandin agonists (1st line)–uveoscleral pathway
2. Miotics–TM pathway
Is IOP useful in screening Glaucoma?
No. about 50% of patients with glaucoma have “normal” range IOP (10 to 21 mm Hg) at Dx
Sx of acute angle closure Glaucoma
- unilateral (rarely bilateral) blurred vision
- halos or rainbows around lights (corneal edema)
- pronounced pain around the eye
- N&V
Signs of acute angle closure Glaucoma
- mid-dilated pupil,
- conjunctival injection,
- cloudy cornea (microcystic corneal edema)
- closed angle
- acutely ↑ IOP
Dx of acute angle closure Glaucoma
Migraine
Risk Factors for Glaucoma
- FHx
- Age
- Race
- Others: DM, ↑IOP, thin central corneal thickness, refractive error (myopia–POAG; hyperopia–PACG).
Surgery indications in patients with glaucoma:
- progressive visual field loss on max meds,
- intolerant of glaucoma meds,
- poorly adherence
Glaucoma surgery includes
- Laser trabeculoplasty for POAG
- Laser iridotomy for PACG,
- incisional (trabeculectomy and tube shunt devices)
Gonioscopy of POAG:
- Normal-appearing, open anterior chamber angle
- No peripheral anterior synechiae (PAS)
Characteristic appearance of optic nerve head in Glaucoma
- loss of rim tissue
- splinter or NFL hemorrhage that crosses the disc margin
- bayoneting
- ↑C/D ratio>0.6
10 layers of retina
vitreous → choroid
- ILM
- NFL
- GCL
- IPL
- INL
- OPL
- ONL
- ELM
- IS/OS
- RPE
Visual field defects in Glaucoma
- nasal step, (nasal field loss)
- paracentral scotoma,
- arcuate scotoma (respect the horizontal midline)
- altitudinal defect,
- tunnel vision
- generalized depression
distinguish Optic atrophy from Glaucoma
- more optic nerve pallor than cupping.
- IOP usually nl
- Color vision and central vision ↓
- Visual field defects respect the vertical midline (typical of intracranial lesions at the chiasm/beyond)
distinguish chronic angle closure glaucoma from POAG
- sx: episodic blurred vision or headache
- gonioscopy:
- Shallow anterior chamber,
- peripheral anterior synechiae (PAS)
examinations of Glaucoma
- complete ocular examination
- baseline optic nerve head
- formal visual field testing
- measure central corneal thickness (affects tonometry)
what to do first if glaucoma damage progresses after meds?
check compliance
which agent will precipitate PACG
anticholinergics
signs of increasing urgency for pressure reduction in acute ACG
- Worsening vision
2. spontaneous arterial pulsations
definition of Angle Recession Glaucoma
- Glaucoma due to the angle recession( usually takes 10 to 20 yrs to develop).
- Angle recession: a tear between the circular and longitudinal fibers of the ciliary body (Gonioscopy:↑ width of CB)
3 biochemical factors that may involved in the pathogenesis of cataract
- Hydration
- Desaturation of lens protein
- Sclerosis
stages of senile cortical cataract
- lamellar separation (grey pupil, reversible)
- incipient (lens striae, peri-)
- immature (swollen lens, shallow AC, iris shadow)
- mature (whole cortex, no iris shadow)
- hypermature
- sclerotic (shrunken, deep AC, tremulous iris)
- morgagnian (liquefied, milky cortex above, nucleus below)
what test may help differentiate optic neuropathy-related and macular visual loss?
color vision test
- optic neuropathy, esp. demyelin. : proportionately >
- macular: degrees =
what is glare?
Glare is when a light source affects our ability to see clearly. (eg. in bright sun or from oncoming headlights while driving at night)
symptoms of cataract
- Slowly(mos/yrs) progressive visual loss or blurring
- Glare (esp. cortical, PSC)
- altered color perception
types of cataract based on sites
- Nuclear: yellow/brown, index myopia
- Cortical: vacuoles/radial, spoke-like, peri-, late
- Post.Subcapsular.:dilation helps, causes, age<50 yr
most common cause of acquired cataract
Age
causes of cataract
- age
- trauma
- toxic(eg. steroids)
- secondary: eg. chronic ant. uveitis, acute ACG
- Endocrine: eg. DM
- metabolic: eg. Ca, Cu
- chromosomal. eg. Down
examinations of cataract
- complete eye: cause VA ↓
2. pre-op
indications of surgery in patients w/ cataract
• visual function
• ocular disease (e.g., lens-related glaucoma or uveitis)
. ease management
cataract related complications
- glaucoma
2. uveitis
nonsurgical Rx in cataract
- corrective lenses
2. mydriasis, esp PSC
surgery for cataract
phacoemulsification (US) + implantation intraocular lens (IOL)
most common complication of cataract surgery
post. capsule opacification (laser post. capsulotomy)
ddx for eye pain
- headache
- eyelids
- conjunctiva
- cornea
- sclera
- uvea
- glaucoma
- optic neuritis
how to detect corneal defects?
Slit lamp examination w/ fluorescein staining
how to classify decreased vision?
- Transient (<24hrs): vascular, CNS, migraine
- > 24 hours
- sudden, painless: vascular, retina, CNS
- gradual, painless: cataract, glaucoma, refractive error, ARMD, DR
- painful:AACG, optic neuritis - Posttraumatic
- axis
ddx of photophobia
- abnl eye: cornea, ant. uveitis
2. nl eye: migraine, meningitis,
ddx of red eye
- adnexal
- conjunctival
- corneal
- others: eg. ant.uveitis, ACG, cluster headache
Relief of pain with the instillation of anesthetic drops (e.g., proparacaine) strongly suggests the etiology of pain is
corneal epithelial disease
Why cant anesthetic drops be used chronically?
these drops inhibit epithelial healing and may cause corneal ulceration.
clinical signs of Dry eye syndrome include
- Poor tear lake (normal meniscus >=0.5mm and convex),
- ↓tear break-up time(blink–>tear film defect by using fluorescein stain: <10s),
- ↓Schirmer test (anesthetized<=5mm in 5min)
what agent can relieve eye pain and photophobia?
cycloplegic drop (e.g., cyclopentolate 1% to 2% t.i.d)
what hx is important for corneal diseases?
Contact lens wear
non-specific Rx for Superficial punctate keratopathy (SPK)
Contact lens wearer: Discontinue
- small: [artificial tears q.i.d.+lubricating ointment q.h.s.]
- large: [Abx ointment+cycloplegic drop]
- non-contact lens wearer: bacitracin/polymyxin B or erythromycin q.i.d
- contact lens wearer: “Fluoroquinolone / aminoglycoside
sx of Dry eye syndrome
- Burning, dryness, foreign body sensation, mildly to moderately decreased vision, excess tearing.
- Often exacerbated by smoke, wind, heat, low humidity, or prolonged use of the eye
- Usually bilateral and chronic .
- Discomfort often out of proportion to clinical signs.
ddx of Dry eye syndrome
causes of SPK
causes of Dry eye syndrome
- Idiopathic: menopausal and post-
- life-style
- evaporative (Lipid layer): blepharitis, meibomian (waking)
- aqueous layer: age (later day / use)
- conjuctival scarring
- corneal refractive surgery
- lacrimal glands: rad, infil, eg. sarcoidosis
- Others:connective tissue diseases(e.g., Sjögren syndrome), drugs, vit A
Schirmer test Technique
1.drying,
2.Schirmer filter paper junction of the middle and lateral 1/3 of the lower eyelid in each eye for 5 min.
3.Eyes are to remain open with normal blinking.
• Unanesthetized(basal and reflex tearing): nl >=15 mm
• Anesthetized,:Topical anesthetic (e.g., proparacaine) (basal tearing) Abnl <=5 mm, <10 mm borderline.
which connective tissue disease is associated with dry eye syndrome?
Sjögren syndrome
Rx for Dry eye syndrome
depend on degree and causes
- artificial tears
- lubricating ointment
- life style
- Cyclosporine 0.05% (chronic, severe, inflamed)
- punctal occlusion
- permanent lateral tasorrhaphy
define Pterygium and Pinguecula
3- or 9-o’clock perilimbal (Related to sunlight exposure and chronic irritation. )
• Pterygium: Wing-shaped fold of fibrovascular tissue arising from the interpalpebral conjunctiva and extending ONTO the cornea. There is no associated thinning of the cornea below these lesions. Usually nasal in location.
• Pinguecula: Yellow-white, flat or slightly raised conjunctival lesion, usually in the interpalpebral fissure adjacent to the limbus, but NOT involving the cornea.
define Pannus
Blood vessels growing into the cornea,
-Usually at the level of Bowman membrane with minimal to no elevation
clinical findings of keratitis
- corneal stroma infiltrate, epithelial defect, stromal thinning,
- stromal edema, mucopurulent discharge, folds in Descemet membrane, AC reaction, hypopyon, conjunctival injection, upper eyelid edema
- severe: Posterior synechiae, hyphema, ↑IOP
most common cause of infectious keratitis
Bacterial organisms (until proven otherwise) -Staphylococcus, Pseudomonas, Streptococcus, Moraxella, Serratia
can topical corticosteroids be used in Infectious keratitis?
Infectious keratitis may worsen significantly with topical CS (esp fungus, atypical mycobacteria, or Pseudomonas.)
what agents can help suppress connective tissue breakdown and prevent the perforation of the cornea?
-matrix metalloproteinase inhibitor (e.g., doxycycline )
-collagen synthesis promoter eg.systemic ascorbic acid (e.g., vitamin C )
[eye shield w/o patch]
when Systemic antibiotics are needed in infectious keratitis?
- scleral extension
- frank or impending perforation
- Neisseria, Haemophilus infections
which organism is involved in patients w/ history of swimming and/or hot tubbing while wearing contact lenses?
Acanthamoeba
Previous LASIK has been implicated as a risk factor for ______________ infections.
atypical mycobacteria
why IOP should be measured in keratitis?
inflammatory open angle glaucoma
how to distinguish acute IOP ↑ from chronic IOP↑?
- corneal edema
- pain
- visual sx
what ddx can be difficult to differentiate from Inflammatory open angle glaucoma?
Steroid-response open angle glaucoma
[significant inflammation→ assume inflammatory→use steroids]
which conditions result in Inflammatory open angle glaucoma?
- Uveitis
- Keratouveitis, esp.HSV
- Trauma/surgery
Rx for Inflammatory open angle glaucoma
- Topical steroid(e.g., prednisolone acetate 1%)
- Mydriatic/cycloplegic
- IOP ↓:
- Topical β blocker
- Topical α-2 agonist
- Topical CAI/oral CAI
- Mannitol
- AC paracentesis - underlying
- surgery: tube shunt; trabeculectomy
- antiviral for HSV
differences between HSV and VZV infection on the face(vesicular skin rash distribution)
- HSV:
- concentrated around the eye;
- oft involves both upper and lower eyelids - VZV:
- along V1 nerve.
- not crossing the midline
- spares the lower eyelid.
pathogenesis of Neurotrophic keratopathy
Occurs in eyes with diminished or absent corneal sensation. →
Denervation causes the corneal epithelium and tear film to become abnormal and unstable. →
impaired healing→an epithelial defect (not treated)→stromal lysis and possibly perforation
what infection desensitize the cornea?
HSV/VZV
how to treat sterile corneal ulcer?
- Abx ointment q2h
- tarsorrhaphy
- sutureless amniotic membrane tissue, sutured/glued amniotic membrane graft, or conjunctival flap
- Oral doxycycline (100 mg b.i.d.),
- Systemic ascorbic acid (e.g., vitamin C 1 to 2 g daily)
- Autologous serum, albumin, or umbilical cord serum eye drops
which oral Abx has good eye wall penetration?
Oral fluoroquinolones
infiltrates in fungal keratitis
- commonly have feathery borders
- surrounded by satellite lesions
- candida mimic bacterial ulcers
1st ddx of Acanthamoeba Keratitis
HSV (pseudodendrites in early stage)
Ring-shaped corneal stromal infiltrate is seen in ________
late stage (3-8wks) of Acanthamoeba Keratitis
radial keratoneuritis can be seen in _________ keratitis
Acanthamoeba
how to diagnose Acanthamoeba Keratitis?
- Corneal scrapings and stains and cultules
- corneal biopsy
- cultures and smears of contact lens and case
- Confocal biomicroscopy
define dendritic and geographic epithelial defect
- dendritic: a thin, linear, branching epithelial ulceration with club-shaped terminal bulbs at the end of each branch
- geographic: a large, amoeba-shaped corneal ulcer with a dendritic edge
characteristics of neurotrophic corneal ulcer
- oval
- smooth border
- interpalpebral fissure
- may progress to stromal melting and perforation
Hutchinson sign
vesicular rash involves tip of the nose in the distribution of the nasociliary branch of V1
pseudodendrites can be seen in ________ keratitis
- VZV
2.Acanthamoeba
[-raised mucous plaques.
-no true terminal bulbs
-not typically stain well with fluorescein.]
how can corneal stain help detect HSV corneal lesions?
- rose bengal or lissamine green: edges of herpetic lesions heaped up with swollen epithelial cells
- fluorescein: the central ulceration
what are the signs of HSV corneal epithelial disease?
- macropunctate
- dendritic
- geographic
- stains
- ↓corneal sensitivity
- Subepithelial scars and haze(ghost dendrites) aft resolution
2 forms of HSV Corneal Stromal Disease
- Disciform keratitis (nonnecrotizing keratitis):
* Necrotizing interstitial keratitis (IK) (uncommon):
Keratic precipitates
Recollections of inflammatory cells on corneal endothelium.
