This document discusses various causes of corneal edema. It begins by explaining that corneal edema can be caused by endothelial dysfunction or situations exceeding the endothelium's barrier and pump capacity. Specific conditions that can lead to corneal edema are then outlined, including persistent epithelial defects, increased intraocular pressure, primary endothelial diseases, Fuch's dystrophy, posterior polymorphous dystrophy, congenital hereditary endothelial dystrophy, iridocorneal endothelial syndrome, and corneal edema induced by cataract surgery or other ocular procedures and injuries. Treatment options are mentioned for selected conditions.

1. Corneal edemaCorneal edema
Othman Al-Abbadi, M.D

2. The common denominator for all of the
conditions is clinical stromal +/- epithelial
edema
May be caused by endothelial dysfunction
or by physiologic situations that exceed
the barrier and pump capacity of the
endothelium

5. Persistent Epithelial DefectsPersistent Epithelial Defects
The epithelium is 200x more
impermeable than the endothelium
◦ loss of the epithelial barrier
◦ pH alterations (due to infective keratitis)
◦ stromal collagenolysis (tear film enzymes)

7. Increased IOPIncreased IOP
elevated IOP combined with normal
stromal SP can create an increase in
corneal thickness
persistent elevated IOP drives fluid
across the endothelium, creating edema
of both the epithelium and stroma
◦ acute angle-closure glaucoma

10. Primary Endothelial diseasesPrimary Endothelial diseases
Can compromise endothelial function by
reducing the effectiveness of both the
barrier and the endothelial pump function
These conditions may result from a
decrease in endothelial
◦ cell function,
◦ cell number,
◦ or both

11. Fuch’s dystrophyFuch’s dystrophy

12. IntroductionIntroduction
dystrophia epithelialis corneae
◦ bilateral central corneal clouding in 13 elderly
patients in 1910
Inherited, bilateral, asymmetric, non-
inflammatory disorder
Characterized by varying degrees of
epithelial and stromal edema, pain,
decreased vision, and corneal guttae

16. GuttaeGuttae
• Described by Vogt at 1921
• Droplike excrescences of the posterior
surface of the cornea
• Seen in:
–Fuch’s dystrophy
–Inflammatory conditions of the cornea
–Hassal-Henle warts;
• peripheral corneal guttae
• without corneal edema nor decreased endothelial cell
count
• With aging

17. Clinical featuresClinical features
Usually starts on the fourth decade of life
Grouped into four stages

18. Stage 1Stage 1
Marked by the onset of corneal guttae
Signs:
◦ central corneal guttae
◦ pigment dusting on the posterior corneal surface
◦ thickened, beaten-metal appearance of
Descemet's membrane
◦ guttae spread to the periphery while progressing
◦ only recognized retrospectively because patients
have no corneal edema and are asymptomatic

19. Stage 2Stage 2
Symptoms:
◦ painless decrease in vision
◦ glare and halos around lights
◦ more severe on awakening
Signs:
◦ varying degrees of epithelial and stromal
edema
◦ Epithelial edema can be seen as small droplets
(bedewing) on slit lamp retroillumination

20. Stage 3Stage 3
Epithelial microcysts coalesce to form
bullae which eventually burst (bullous
keratopathy)
Wrinkles in Descemet's
membrane(striae) develop
Signs:
◦ Recurrent corneal erosions
◦ microbial ulceration
◦ persistent pain & FB sensation

21. Stage 4Stage 4
subepithelial pannus
Marked reduction of V/A
Reduction of pain
Reduction of epithelial edema
Persistence of stromal edema
Markedly thickened cornea

22. EpidemiologyEpidemiology
Autosomal dominant with variable
expressivity
3-1 female-male
30% of population <40 y/o have guttae
70% of population >40 y/o have guttae
◦ 3.8% have more than stage 1
◦ 0.1% have epithelial edema or bullae

23. Descement membraneDescement membrane
Normally
◦ Type IV collagen
◦ Anterior banded portion
 Fixed thickness
 3 μm
◦ Posterior non-banded portion
 Variable thickness
 3μm at age 20 & 10 μm at age 80
 Average 9μm

25. HistopathologyHistopathology
Dysfunctional & diseased endothelium
Posterior nonbanded portion becomes
banded
On specular microscopy, the endothelial
cells are large and lose their hexagonal
appearance
studies suggest that diminished pump
function, rather than increased
permeability, is the cause of corneal
edema in Fuchs' endothelial dystrophy.

26. Posterior Polymorphous DystrophyPosterior Polymorphous Dystrophy

27. IntroductionIntroduction
Autosomal dominant
Bilateral
Variable expression
Majority are asymptomatic
Some may develop stromal edema and
secondary epithelial edema that causes
severe and permanent impairment in
visual acuity

28. PresentationPresentation
1. Small asymptomatic, discrete, round gray
vesicular lesion within an otherwise clear
cornea (most common)
◦ On high magnification… appear as an
indentation or “pox mark” on the
endothelium
1. Band lesions & small, diffuse gray
endothelial opacities
2. Larger geographic lesions or a
coalescence of grouped vesicles

30. HistopathologyHistopathology
Presence of epithelial-like cells within
focal areas of the endothelium
◦ These cells possess multiple characteristics of
epithelial cells
The posterior zone resembles the
anterior banded zone

31. Congenital Hereditary EndothelialCongenital Hereditary Endothelial
DystrophyDystrophy

32. IntrodutionIntrodution
“corneitis interstitialis in utero” in 1893
“congenital hereditary endothelial
dystrophy” in 1960
Bilateral
SYMMETRIC
causes corneal opacification from limbus
to limbus, without clear regions

33. Clinical manifestationClinical manifestation
Gray-white diffuse corneal clouding
Within the first 6 months of life
Corneal diameter and IOP are normal
No signs of inflammation or
vascularization
No associated systemic disease
Rarely unilateral with good vision in the
non-involved eye

35. HistopathologyHistopathology
Abnormal collagen tissue is found
between the normal Descemet's
membrane and the endothelium
Anterior banded layer is thick
Posterior collagenous material that is
much more disorganized than the
nonbanded collagen

36. InheritanceInheritance
Inherited in an autosomal dominant or
autosomal recessive fashion
Recessive form presents at birth, rarely
progresses, is asymptomatic, and is
associated with nystagmus
Dominant form appears at age 1-2,
slowly progressive, lacks nystagmus, and is
commonly associated with photophobia
and tearing

37. Iridocorneal Endothelial SyndromeIridocorneal Endothelial Syndrome

38. IntroductionIntroduction
Continuum of one disease that includes
the iris nevus (Cogan-Reese) syndrome,
Chandler's syndrome, and essential iris
atrophy
Unilateral
Acquired disorder of the corneal
endothelium
Young adults

39. Clinical manifestationsClinical manifestations
Iris nodules
Varying degrees of iris atrophy
Peripheral anterior synechiae
Correctopia
Elevated IOP
Corneal edema

42. ChronicityChronicity
Abnormal corneal endothelium
Grow in a membrane
Cover the angle
Glaucoma
Grow onto the anterior surface of the
iris
Iris “nevus” syndrome
Contraction of the membrane
Anterior synechiae
Correctopia & Iris atrophy

43. TreatmentTreatment
Bimodal
◦ Glaucoma
◦ Corneal edema

46. Cataract surgery inducedCataract surgery induced
Most common cause of iatrogenic
corneal edema
Revesible:
◦ high hydrostatic pressure from the flow
◦ manipulation of instruments in the eye may
cause localized edema at the incision site as
well
◦ inadvertent touch of instruments to the
endothelium may cause localized cell lysis

47. Preexisting endothelial diseasePreexisting endothelial disease
Cataract extraction is usually successful as long
as epithelial edema is not present and stromal
thickness is <600 μm
Corneal edema should be evident on
examination and the patient should report
symptoms of morning blurring before the
ophthalmologist considers combined corneal
transplantation and cataract surgery
Controversy exists as to whether the best
postoperative results occur with combined PKP
and cataract extraction, PKP before or after

48. Surgical traumaSurgical trauma
Pseudophakic corneal edema is the
leading indication for PKP in US since mid
80s… before was keratoconus
Vitreous touch to the cornea can cause
corneal edema by mechanical
ballottement of the endothelium
Vitreous incarcerated into the cataract
wound may cause incisional corneal
edema that may progress over the entire
cornea

49. Cataract surgery +/- PC/IOL is currently
associated with 2-5% endothelial loss
Closed-loop IOLs was blamed for 24-62%
endothelial loss previously due to
repeated endothelial touch leading to
stimulated inflammation, bleeding +/-
glaucoma

50. BSS Plus is considered more endothelial
friendly, with ingredients such as glutathione,
sodium bicarbonate, and glucose

51. Brown-McLean syndromeBrown-McLean syndrome
Corneal edema involving the peripheral 2 to 3
mm of the cornea
Starts inferiorly sparing the central portion
Associated with a punctate orange-brown
pigmentation on the endothelium
Central cornea guttata is frequently seen
Most frequently after ICCE
May occur following ECCE, phaco & PPV
May progress to complete endothelial
decompensation

52. Decreasing iatrogenic cornealDecreasing iatrogenic corneal
edemaedema
Improved surgical technique
better microsurgical instrumentation
more biocompatible irrigating solutions
acceptance of viscoelastic materials
increasing number of cataract surgery
cases and an enlarging elderly population
will likely make pseudophakic corneal
edema a problem for some time

53. Vitreoretinal
surgery
Refractive
surgery
intraocular FB

54. VR surgeryVR surgery
Silicone oil and perfluorocarbon cause
edema
Migration of oil or gas into A/C
◦ Mechanically damage the endothelium
◦ Block aqueous nutrients
Phakic and pseudophakic vs aphakic
Inferior iridectomy in cases of silicone oil
retention & aphakia can limit access of
silicone oil into A/C by allowing normal
aqueous flow through the iridectomy site

55. Refractive surgeryRefractive surgery
Radial keratotomy may be associated
with diurnal variation in corneal thickness
PRK on rats showed increased apoptosis
of corneal keratocytes and endothelial
cells
Corneal endothelial analysis following
LASIK verified pleomorphism with
definite loss of endothelial cells and
altered cell morphology acutely
manifesting as corneal edema

56. Corneal trauma (FB)Corneal trauma (FB)
External & penetrating traumas can
induce corneal edema
When a penetrating object lodge in the
angle, it may be difficult to see with
gonioscopy or through the microscope at
the time of surgery
Optimum treatment for metallic foreign
bodies is surgical removal ASAP

59. Chemical injuryChemical injury
Normal pH of endothelium= 6.8-8.2
Damages the plasma membrane reducing
the effectiveness of the barrier function
Chemical injuries alter the pH decreasing
the amount of stromal Bicarbonate buffer
reducing the pump function

61. InflammationInflammation
Corneal edema depends on the severity
of the inflammatory process, its duration,
and the health of the endothelium
Can be induced by uveitis, herpes
simplex, herpes zoster, sarcoidosis &
post-op when the endothelium is more
vulnerable

62. Increased IOPIncreased IOP
If the endothelium is already stressed and
diseased, a relatively low IOP can cause
corneal edema increasing the threshold
◦ postoperative cataract surgery
◦ postoperative PKP
◦ severe Fuchs' dystrophy

63. Contact lensesContact lenses
When covered with a contact lens, the
cornea can receive oxygen from three
sources:
◦ oxygen dissolved in tears that float behind the
lens
◦ oxygen that passes directly through the lens
◦ oxygen that passes into areas of the cornea not
covered by the lens
Oxygen transmission of CL= Dk/L
◦ L is lens thickness
◦ Dk of CL is the oxygen transmissibility coefficient

65. Contact lens hypoxia often presents as
epithelial microcysts in the central
portion of the cornea
Corneal edema results from depletion of
glycogen and accumulation of lactic acid
within the cornea... The pH changes of
lactic acid further exacerbate the
endothelial barrier capacity