Transcript Treatment of Keratoconus Using Riboflavin

Authors: Anne Keating, M.D. 1,2 , Kathryn Colby, M.D., Ph.D. 2 ,
Roberto Pineda, M.D. 2 , Michael Endl, M.D. 4 , Thomas Elmer,
M.D. 4 , Sandra Everett, M.D. 1 and James Reidy, M.D. 1
1 SUNY
Buffalo, 2 Massachusetts Eye and Ear Infirmary, 3 Fichte
Endl Elmer Eyecare, Buffalo, NY
Financial Disclosure: The authors of this poster have no
financial interest in the subject matter of this poster.
 Keratoconus is a bilateral disease of corneal collagen fibers that leads to
thinning of the cornea and protrusion of the anterior portion of the cornea.
The disease affects approximately one in 2000 people of all genders and
ethnic groups. The thinning and protrusion of the cornea can lead to tears in
the cornea and acute hydrops, where there is sudden corneal edema and
eventual scarring and loss of vision. Even without this complication, patients
with keratoconus often have decreased vision due to abnormally high amounts
of astigmatism, or irregularly shaped corneas. Approximately 20% of people
affected by keratoconus will require at least one corneal transplant during their
lifetime. The aim of our treatment is to strengthen the corneas by crosslinking the collagen via application of riboflavin and stimulation by UV light
so that they do not slowly weaken, reduce vision, cause scarring, and possibly
require corneal transplantation. The expectation is that treatment will slow the
progression of the disease and avoid the need for a corneal transplant. The
treatment has been performed in Europe for the past decade with remarkably
favorable results (see Table 1 and references).
The Caporossi-Baiocchi-Mazzotta (CBM) VEGA X-linker was
developed by Aldo Caporossi, Cosimo Mazzotta, and Stefano
Baiocchi in collaboratioin with the Italian firm C.S.O. The CBM
X-linker is a device that emits ultraviolet (UV) radiation at 370
nm (peak absorption of riboflavin) (figure 1).
The device is designed to produce a timely, homogeneous dose of
irradiation and deliver it to a 9 mm diameter spot size at a
distance of between 1.5 and 1.8 cm. This working distance
allows for more efficient focusing on the cornea. A small digital
video camera is included in the center of the UV-A array in order
to monitor the aiming-beam alignment and to control the
centration of the irradiated area. The picture from the video
camera is shown on an LCD (liquid crystal display) monitor
mounted on the control unit of the equipment (figure 2).
 The goal is for two groups of approximately 66 patients to
be included in the study. One eye from the first group will
undergo treatment, while the second group of age matched
individuals will serve as a control. This is a prospective,
randomized, blinded study. Each patient will be randomized
at the beginning of enrollment in the study and will receive a
randomization number.
 The treated and control groups will undergo the following: Two days prior to the
procedure, patients will start taking 600 mg of ibuprofen twice daily, which they will
continue for a total of 5 days. A drop of 1% pilocarpine will be placed into the treated
eye. Topical anesthesia (2% lidocaine jelly) will then be applied and an eyelid speculum
will be placed to keep the eyelids open. The central 8.5-9 mm of corneal epithelium will
be removed cautiously with the Amoils Epithelial Scrubbe. Riboflavin 0.1% solution
will be applied (10 mg riboflavin-5-phosphate in 10 ml dextran T-500 20% solution,
supplied in a sterile, single dose container- figure 2) to the cornea every 2-3 minutes for
15 minutes prior to beginning the UV light. The UV source will be from the CBM
VEGA X-linker (CSO, Florence, Italy). A wavelength of 370 nm will be used to direct
5.4 J/cm2 to the area of cornea that was debrided for 30 minutes. Every 5 minutes, the
UV light will pause briefly while another drop of riboflavin is applied. The distance
from the UV source to the cornea will be 1.5 to 5.4 cm. After treatment, the cornea
will be rinsed with chilled saline and 2-4 drops of moxifloxacin (Vigamox™, Alcon,
Fort Worth, TX) will be instilled, along with 1-2 drops of cyclopentolate 1%
(Cyclogel™, Alcon, Fort Worth, TX). A bandage contact lens (FOCUS, 8.4 BC) will be
placed prior to sending the patient home and this will be removed after complete reepitheliaization has occurred, typically within 5 to 7 days. The patients will be asked to
use the moxifloxacin four times a day and Acular LS four times a day until the 1 week
post-procedure visit (at which time the epithelium will be examined for healing).
INCLUSION CRITERIA for participation:
a. age between 16-35
b. no prior history of ocular surgery
c. treatment eye must have a corneal power (K power) of between 47 D and
60 D (a measurement of the steepness of the cornea) in the steepest meridian
 d. corneal thickness must be greater than 400 µm
 d. absence of corneal scarring in the eye to be treated
 e. patients must meet the diagnostic criteria for keratoconus, which include
one or more of the following features:
 -high myopia
 -corneal ectasia as viewed by slit-lamp exam or measured by pachymetry
 -Vogt’s striae (fine, parallel striations in the corneal stroma)
 -topographic findings of superior flattening and inferior steepening of the
cornea with 3 or more diopters of difference (see Figure 4)
 -presence of Fleischer ring
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Best Corrected Visual Acuity
Corneal Topography as measured by Pentacam
Corneal pachymetry (both by ultrasound and pentacam)
Corneal hysteresis as measured by Ocular Response
Analyzer
Intraocular Pressure measured by tonopen
Endothelial Cell Count
The treatment of keratoconus using UVA induced
riboflavin corneal collagen cross linking has been
conducted in Germany and Italy over the past decade
with fairly consistent and positive results. The table
below summarizes the follow-up and results.