Cole Eye Institute - Cleveland Clinic

Innovations
Retinopathy of Prematurity (ROP)
Retinopathy of Prematurity (ROP), a leading cause of childhood blindness
worldwide, has no FDA-approved medical therapy. ROP involves initial
destruction of retinal vessels during hyperoxia and the subsequent
abnormal growth of blood vessels in response to low oxygen states. These
vessels bleed and can exert traction, causing retinal detachments.
The current paradigm for preventing unfavorable outcomes from ROP is
centered on the treatment of the angiogenesis seen in ROP by limiting the
substrate-causing pathologic neovascularization through destructive laser
ablation of the retina. However, another novel approach to preventing
vision loss from ROP is to direct the orderly development of retinal vessels
during phase I by stimulating a key transcription factor, hypoxia inducible
factor-1 (HIF-1), that is inhibited by the hyperoxia of phase I.
Using a gene reporter system, Jonathan Sears, MD, and associates at
the Cole Eye Institute have uncovered small molecules with rapid onset
and a short half life that enable the retina to develop in an orderly and
sequential fashion during hyperoxia, a phase that normally causes vascular
obliteration. This induces the normal development of the retina and
eliminates the stimulus for pathologic blood vessel growth and subsequent
retinal detachment.
Multiple Advantages Make DALK an Excellent Alternative
to PK in Eyes with Anterior Corneal Pathologies
Penetrating keratoplasty (PK) remains the gold standard surgery for eyes
with corneal disease needing transplantation. This full-thickness procedure
is highly effective in restoring vision, but its drawbacks include a prolonged
recovery, a fragile wound and the attendant risk of endothelial rejection.
Deep anterior lamellar keratoplasty (DALK), in which the anterior and
middle layers of the diseased cornea are replaced with healthy donor
tissue, was developed as an alternative procedure to PK in eyes with a
normal Descemet’s membrane and endothelial cells. However, DALK is
more technically challenging and takes longer to perform than PK, so it has
not been widely adopted by corneal transplant surgeons.
Despite the downside of a prolonged procedure and because DALK has
significant advantages, Cole Eye Institute corneal surgeon Bennie H. Jeng,
MD, mastered the technique for DALK and began offering it to appropriate
patients about one year ago.
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“One of the major advantages of DALK over PK is that it eliminates the
chance of endothelial rejection, which accounts for nearly all cases of graft
rejection. In addition, the cornea is much stronger after DALK compared
with PK, which minimizes the risk for late trauma-induced wound
dehiscence that can persist for decades after PK,” he says. Furthermore,
DALK cuts healing time and time to visual recovery to half of the time as
for PK. The opportunity to provide faster visual rehabilitation and reduced
long-term risks of graft rejection and wound dehiscence more than justify
the extra time it takes to do this procedure.
In Dr. Jeng’s experience, the functional outcomes achieved with DALK
have been excellent and comparable to those of PK for similar indications.
To date, there have been no long-term postoperative complications or any
episodes of rejection. However, because of the technically challenging
nature of the procedure, the DALK technique may occasionally need to be
converted to a full-thickness transplant. Dr. Jeng’s intraoperative conversion
rate from DALK to PK has been about 5 percent.
Diffuse Illumination view of the right eye of a patient
three months after DALK for keratoconus (top).
Slit-beam view demonstrates a trace amount of
interface haze which later faded away. Final BCVA
after all sutures were removed was 20/20 (bottom).
Cole Eye Institute