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Case Study #040104 |
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| Corneal Sequestration is a necrosis (cell
death) of the middle of the cornea (the stroma). It can be
conformational (genetic) or sometimes of infectious origin
(e.g., set off by the herpes virus.) Persian and Himalayan
cats are particularly predisposed to corneal sequestration.
The necrotic area is dark in color and prevents vision through
this area. Progression to complete blindness is rare though
partial loss of the visual field is not uncommon in advanced
cases.
To treat this condition, a
corneal allograft is sometimes used as
a transplant graft when the lesion is very deep into the cornea.
The central layer, or stroma, from the donor cornea is actually
what is transplanted. The procedure is known as a partial
thickness corneal transplant (lamellar keratoplasty). Lamellar
Keratoplasty affords complete removal of the diseased cornea,
restoration of the anatomic thickness of the cornea and corneal
clarity which preserves vision.
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Patient Name: Chopper
Age/Sex: 10 years / Male
Breed: Domestic Shorthair |
Condition:
Corneal Sequestration
Treatment: Corneal Transplant
Graft Type: Corneal
Allograft |
Surgeon:
Dr. Bruce Silverman
Clinic: Complete Animal Eye Care
Location: Sherman Oaks, CA
Telephone: (818) 986-4356 |
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Figure
1 shows a patient with a very large sequestrum.
It is the large dark kidney bean-shaped area in the lower
right hand portion of the cornea. |
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The surgeon used Ultrasound
Biomicroscopy (UBM) to see the internal anatomy of the
cornea. This equipment has a 50 MHz probe that is extremely
sensitive and can determine very precisely the depth of
the lesion within the middle layer of the cornea. Figure
2 shows a sample ultrasound picture of a
sequestrum. The white hyperechoic area shows exactly the
thickness and location of the sequestrum within the cornea.
This allows for a more accurate excision of the lesion
to the exact depth needed. |
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A special
vacuum trephine is used to make a precise and delicate
cut of the required diameter partially through the thin
cornea. Its control is so fine that ¼ turn moves
the cutting edge 65 microns (0.065 millimeter) deeper
into the cornea. The concept is to remove the surface
layers containing the sequestrum but leave the important
endothelial lining cells in place. |
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The allograft
is cut in a similar location using a special donor trephine
that makes a slightly larger diameter full thickness cut
through the cornea. The surgeon then removes the outer
and inner layers of the donor cornea. This leaves just
the stroma to be transplanted. |
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Sutures
smaller than a human hair (9-0 suture) are carefully placed
around the edges of the graft and the donor cornea is
secured with 16 to 20 sutures using microsurgical techniques
and an operating microscope. |
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Figure
3 shows the recipient at a check-up
2 weeks following surgery. Fluorescein dye has been
placed in the eye to visualize the intactness of
the corneal epithelium. The donor cornea is healing
into place as expected and the cornea remains clear,
which is a good sign of overall health of the endothelial
cells and the transplanted donor corneal stroma. |
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Figure
4 shows our patient "Chopper"
at 3 months follow up. He is doing well and has
a clear, healthy cornea. |
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| Dr. Silverman is not affiliated with Veterinary Transplant Services. He has kindly supplied the photographs and information for this presentation, with the consent of his patient's owners, to illustrate a representative case that benefited from transplant of a corneal allograft from VTS. For more information about VTS allografts, please contact Dr.
Newman. |
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Figure
1 
