CORNEAL DYSTROPHIES Flashcards
list general characteristics of corneal dystrophy
bilateral, symmetric, and have no neovascularization
list 1 anterior corneal dystrophy?
Epithelial basment membrane dysrophy (EBMD)
what is the most common anterior corneal dystrophy?
EBMD
what causes EBMD?
- Basal epithelial cells secrete an excessive amount of basement membrane that leads to thickening of the basement membrane and causes weak hemidesmosomes formation –> this causes corneal epithelial cells to be trapped beneath the basmement membrane and prevents them from progressing anteriorly.
symptoms of EBMD?
- Asymptomatic – unless central corneal is involved then they will have blurry vision.
- Epiphora
- Severe pain if RCE.
signs of EBMD?
- Map – irregular islands of thickened, gray, hazy epithelium.
- Dot – Dot-like (microcystic) epithelial lesions.
- Fingerprint – Whorled/concentric lines that look like fingerprints.
- Negative staining with NaFl.
- Possible RCE – due to the lack of hemidesmosome between basal epithelial cells.
tx for anterior and stromal corneal dystrophies?
- ATs
- If RCE – Abx + ATs + bandage CLs
- if central scarring – consider phototherapeutic keratectomy (PTK), lammellar keratoplasty (DALK), superficial keratectomy, or penetrating keratoplasty (PK).
what are 3 types of stromal corneal dystrophies?
- macular dystrophy
- granular dystophy
- lattice dystrophy
which sotrmal dystophy is autosomal dominant and which are autosomal recessive?
AD = granular dystophy & lattice dystrophy
AR = macular dystrophy
which stromal corneal dystrophy is most visually disabling?
macular dystrophy
what causes macular dystrophy?
- It occurs due to an error in Keratan sulphate (GAG) metabolism that leads to an accumulation of GAGs
signs of macular dystrophy?
- Central anterior stromal haze
- Greyish white, dense, focal, poorly delineated spots –>
- Irregular corneal surface (due to stromal deposits) –>
- Increased in lesion size & stromal haze –>
- Increasing opacification involving full thickness stromal limbus-to-limbus.
what stains macular dystrophy?
stains with Alcian Blue
what age does macular dystrophy occur?
ages 3-9
what is the most common stromal corneal dystrophy & which is the least?
- most common = granular dystrophy
- least common = macular dystrophy
what are the 2 types of granular stromal corneal dystrophy?
- type 1 = Characterized by amorphous hyaline deposits w/in stroma that stains bright red with Masson trichrome.
- type 2 = Characterized by amorphous hyaline & amyloid deposits w/in stroma that stains with Masson trichrome & Congo red.
signs of granular dystrophy?
Type 1 signs (in order):
* Small, white, sharply demarcated deposits in the central anterior stroma.
* Gradual confluence
* Hazing of intralesional space
Type 2 signs:
* Superficial fine opacities that appear like rings, disc, stars, or snowflakes.
* Deeper linear opacities – like lattice dystrophy.
what is lattice dystrophy?
accumulation of amyloid deposits in the anterior stroma.
lattice dystrophy stains with?
- Stains with Congo red
signs of lattice dystrophy?
- Anterior stromal glassy refractile dots which coalesce into refractile branching lines (amyloid deposits).
which anterior and stromal dystophy have RCE and how often do they occur?
- EBMD - frequently
- macular dystophy - occasionally
- granular dystophy - rare
- lattice dystophy - common
what is the pneumonic to remember types of depositis and staining associated with stromal dystophies?
Marilyn Monroe Always Gets Her Men in LA County:
M = Macular dystophy
M = Mucopolysaccharide deposits
A = Alician Blue
G = Granular dystrophy
H = Hylaline deposits
M = Masson Trichrome
L = Lattice
A = Amyloid deposits
C = Congo Red
what are 2 types of posterior corneal dystrophies?
- Posterior polymorphous corneal dystrophy
- Fuch’s endothelial corneal dystrophy
what is posterior polymorphous corneal dystrophy (PPMD)?
- It is characterized by excessive proliferation & migration of of Descemet & endothelial cells.
what age does PPMD occur?
age 20-30
signs of PPMD?
- Hallmark = vesicular lesion – that can also appear as linear & band-like (train-track lesions), or mix.
- corneal edema
- Angle closure glaucoma – from peripheral anterior synechiae.
tx for PPMD?
- same as anterior and stromal dystophy + treat increased IOP.
what is Fuch’s Endothelial Dystrophy?
characterized by progressive endothelial cell loss (hallmark) due to excess descemet’s membrane.
symptoms of Fuchs?
- Blurry vision – vision is worse in the morning b/c there is an accumulation of fluid in the cornea while sleeping (stromal swelling)
- Pain – if bullous keratopathy
what are the signs for each stage of Fuch’s?
- Stage 1 – initial manifestation of the disease is central corneal guttae.
- Stage 2 – Decreased endothelial cell density associated with pleomorphism & polymegathism & stromal edema causes a fine gray haze (<500cells/mm^2).
- Stage 3 – characterized by bullous keratopathy, which is epithelial microcyst that can coalesce to form large intra & interepithelial cystic spaces or bullae which can lead to epithelial erosions & fingerprint lines –> painful.
- Stage 4 – characterized by avascular subepithelial fibrosis & scarring between the epithelium & Bowman’s membrane.
what is the min cell count needed to prevent corneal edema?
- A min of 500-700 cells/mm^2 are required to prevent corneal edema
tx for Fuch’s?
- Hypertonic saline solutions (Muro 128) gtts or ung – for stromal edema.
- ATs & bandage CLs – for epithelial bullae or RCE.
- DSAEK / DMEK – for severe cases.
are posterior corneal dystophies associated with RCE?
- NO!!
what inheritance are posterior corneal dystophies?
AD
why does stromal edema occur in fuch’s?
endothelial cell count is too low which leads to compromised endothelial pump mechanism.
