مجال
التميز
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تميز دراسي و بحثي
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البحوث المنشورة
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البحث (1):
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عنوان البحث:
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Standard
Versus Accelerated Riboflavin–Ultraviolet Corneal Collagen Crosslinking: Resistance
Against Enzymatic Digestion
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رابط إلى البحث:
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تاريخ النشر:
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27/04/2015
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موجز عن البحث:
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Purpose
To
examine the effect of standard and accelerated corneal collagen crosslinking
(CXL) on corneal enzymatic resistance.
Setting
School
of Optometry and Vision Sciences, Cardiff University, Cardiff, United
Kingdom.
Design
Experimental
study.
Methods
Sixty-six
enucleated porcine eyes (with corneal epithelium removed) were assigned to
6 groups. Group 1 remained untreated, group 2 received dextran eyedrops,
and groups 3 to 6 received riboflavin/dextran eyedrops. Group 4 had standard
CXL (3 mW/cm2 ultraviolet-A for 30 minutes), whereas
groups 5 and 6 received accelerated CXL (9 mW/cm2 for 10
minutes and 18 mW/cm2 for 5 minutes, respectively).
Trephined central 8.0 mm buttons from each cornea underwent pepsin digestion.
Corneal diameter was measured daily, and the dry weight of 5 samples from
each group was recorded after 12 days of digestion.
Results
All
CXL groups (4 to 6) took longer to digest and had a greater dry weight at 12
days (P < .0001) than the nonirradiated groups (1 to 3) (P <
.0001). The time taken for complete digestion to occur did not differ between
the standard and accelerated CXL groups, but the dry weights at 12 days
showed significant differences between treatments: standard CXL 3 mW >
accelerated CXL 9 mW > accelerated CXL 18 mW (P <
.0001).
Conclusions
Standard
and accelerated CXL both increased corneal enzymatic resistance; however, the
amount of CXL might be less when accelerated CXL is used. The precise amount
of CXL needed to prevent disease progression is not yet known.
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البحث (2):
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عنوان البحث:
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Enzymatic
Resistance Of Corneas Crosslinked Using Riboflavin In Conjunction With Low
Energy, High Energy, And Pulsed UVA Irradiation Modes
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رابط إلى البحث:
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تاريخ النشر:
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20/01/2016
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موجز عن البحث:
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PURPOSE:
To
investigate the effect of various riboflavin/ultraviolet light (UVA)
crosslinking (CXL) protocols on corneal enzymatic resistance.
METHODS:
A
total of 66 enucleated porcine eyes, with the corneal epithelium removed,
were divided into 6 groups. Group 1 remained untreated. Groups 2 to 6
received riboflavin/dextran for 30 minutes. Group 3 underwent standard CXL
(SCXL) with 3 mW/cm(2) UVA for 30 minutes (total energy dose 5.4 J/cm(2)).
Groups 4 and 5 underwent high intensity CXL (HCXL) using 30 mW/cm(2) UVA for
3 minutes (5.4 J/cm(2)) and 30 mW/cm(2) for 4 minutes (7.2 J/cm(2)),
respectively. Group 6 was exposed to 8 minutes of 30 mW/cm(2) UVA in a
10-second on/10-second off pulsed-radiation mode (p-HCXL; 7.2 J/cm(2)). A
central 8-mm disk from each cornea was submerged in pepsin digest solution at
23°C and measured daily. After 13 days, the dry weight was recorded from 5
samples in each group.
RESULTS:
The
CXL-treated corneas took longer to digest than nonirradiated corneas (P <
0.0001). Differences in digestion time also were observed between CXL groups,
such that, HCXL (5.4 J/cm(2)) < SCXL (5.4 J/cm(2)) < HCXL (7.2 J/cm(2))
< p-HCXL (7.2 J/cm(2); P < 0.0001). The dry weight of the SCXL (5.4
J/cm(2)) group was higher than the HCXL (5.4 and 7.2 J/cm(2); P < 0.001)
and p-HCXL 7.2 J/cm(2) (P <0.05) groups. No difference was detected
between the HCXL and p-HCXL 7.2 J/cm(2) groups.
CONCLUSIONS:
The
intensity and distribution of the crosslinks formed within the cornea vary
with different UVA protocols. The precise location and amount of crosslinking
needed to prevent disease progression is unknown.
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البحث (3):
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عنوان البحث:
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An Investigation
Into Corneal Enzymatic Resistance Following Epithelium-Off And Epithelium-On Corneal
Cross-Linking Protocols
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رابط إلى البحث:
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تاريخ النشر:
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17/10/2016
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موجز عن البحث:
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The
aim of this study was to investigate corneal enzymatic resistance following
epithelium off and on riboflavin/UVA cross-linking (CXL). One hundred and
fourteen porcine eyes were divided into four non-irradiated control groups
and seven CXL groups. The latter comprised; (i) epithelium-off, 0.1%
iso-osmolar riboflavin, 9 mW UVA irradiation for 10 min, (ii)
disrupted epithelium, 0.1% hypo-osmolar riboflavin, 9 mW UVA for
10 min, (iii) epithelium-on, 0.25% hypo-osmolar riboflavin with 0.01%
benzylalkonium chloride (BACS), 9 mW UVA for 10 min, (iv)
epithelium-on, 5 min iontophoresis at 0.1 mA for 5 min with
0.1% riboflavin solution, 9 mW UVA for 10 min or (v) 12.5 min,
(vi) epithelium-on, prolonged iontophoresis protocol of 25 min with
1.0 mA for 5 min and 0.5 mA for 5 min with 0.25%
riboflavin with 0.01% BACS, 9 mW UVA for 10 min or (vii)
12.5 min. Enzymatic resistance was assessed by daily measurement of a
corneal button placed in pepsin solution and measurement of corneal button dry
weight after 11 days of digestion. This study revealed that the enzymatic
resistance was greater in CXL corneas than non-irradiated corneas
(p < 0.0001). Epithelium-off CXL showed the greatest enzymatic
resistance (p < 0.0001). The prolonged iontophoresis protocol
was found to be superior to all other trans-epithelial protocols
(p < 0.0001). A 25% increase in UVA radiance significantly
increased corneal enzymatic resistance (p < 0.0001). In
conclusion, although epithelium-on CXL appears to be inferior to
epithelium-off CXL in terms of enzymatic resistance to pepsin digestion, the
outcome of epithelium-on CXL may be significantly improved through the use of
higher concentrations of riboflavin solution, a longer duration of
iontophoresis and an increase in UVA radiance.
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البحث (4):
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عنوان البحث:
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An
Investigation Of The Effects Of Riboflavin Concentration On The Efficacy Of Corneal
Cross-Linking Using An Enzymatic Resistance Model In Porcine Corneas
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رابط إلى البحث:
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تاريخ النشر:
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01/02/2018
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موجز عن البحث:
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PURPOSE:
To
investigate riboflavin concentration on enzymatic resistance following
corneal cross-linking (CXL).
METHODS:
Ninety-six
porcine eyes were divided into five groups in two treatment runs. Group 1
remained untreated. Group 2 received riboflavin 0.05%, group 3 riboflavin
0.1%, group 4 riboflavin 0.2%, and group 5 riboflavin 0.3%. Treated eyes
underwent CXL with ultraviolet A at 9 mW/cm2 for 10 minutes. Eight-millimeter
discs from each cornea were submerged in pepsin digest solution. In the first
run, disc diameters were measured daily. After 10 days, dry weights were
recorded from five samples in each group. In the second run, dry weights were
recorded in five samples in each group at 10 and 20 days.
RESULTS:
CXL-treated
corneas took longer to digest than untreated (P < 0.001). Although eyes
treated with higher riboflavin concentrations generally took longer to
digest, there were no significant differences between groups (P = 0.3). Dry
weights at 10 days demonstrated, with each increase in concentration, an
increase in weight of residual undigested tissue (P < 0.001). In the
second run, with each increase in riboflavin concentration there was an
increase in weight of residual tissue (P < 0.001) at 10 days. At 20 days,
the dry weight was lower with 0.05% riboflavin compared to 0.3% (P <
0.001) and 0.2% and 0.1% solutions (P < 0.05), with no other difference
between groups.
CONCLUSIONS:
There
is a consistent dose-response curve with higher concentrations of riboflavin
achieving greater CXL efficacy, suggesting that manipulation of riboflavin
dosage as well as the UVA protocol can be used to optimize CXL.
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