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| Identifier |
000414174 |
| Title |
Μελέτη της διασύνδεσης κερατοειδικού κολλαγόνου και του συνδυασμού της με επιφανειακή φωτοεκτομή καθοδηγουμένη απο την τοπογραφία για την αντιμετώπιση του κερατοκώνου |
| Alternative Title |
Corneal collagen crosslinking alone or combined with topography guided photorefractive keratectomy for the treatment of keratoconus |
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Author
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Κονταδάκης, Γεώργιος Α.
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Thesis advisor
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Παλλήκαρης, Ιωάννης
Τσιλιμπάρης, Μιλτιάδης
Μοσχανδρέα, Ιωάννα
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Reviewer
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Μελισσάς, Ιωάννης
Τσατσάκης, Αριστείδης
Κυμιωνής, Γεώργιος
Τηνιακού, Κωνσταντίνα
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| Abstract |
Purpose: To evaluate experimentally and clinically the results of corneal collagen crosslinking
(CXL) and of it’s combination with preceding simultaneous topography-guided
photorefractive keratectomy (tPRK-CXL) with solid state laser for progressive keratoconus.
In the experimental study, we focused on the in-vitro evaluation of the immediate effect of
CXL on corneal hydration and stiffness. Clinically, the target of the study was to evaluate the
results of CXL and of tPRK-CXL for progressive keratoconus and make comparison
between techniques regarding topographic stability, visual acuity, keratometry and in vivo
corneal microscopy. Additionally, we focused on the effect of CXL on corneal innervation,
corneal sensitivity and tear function in patients with keratoconus.
Methods: In the experimental study forty two corneal buttons were divided in two groups;
one was irradiated to simulate CXL according to the clinically applied protocol.
Subsequently, both groups were brought to osmotic equilibrium with dextran 20% and each
button underwent thickness measurement, and measurement of force versus deformation by
compression. The hydration (%) of each button was calculated. For the prospective
comparative evaluation of CXL and tPRK-CXL thirty eyes received combined tPRK with a
solid state laser (maximum ablation depth 50μm) followed by CXL, and 30 eyes received
CXL alone. Groups were matched in terms of age and keratoconus stage and corrected
distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), keratometry, and
corneal confocal microscopy findings were compared. For the evaluation of innervation and
tear film we conducted a prospective, interventional case series with twenty four patients
with bilateral keratoconus (30 eyes) who underwent CXL. Confocal microscopic analysis of
corneal subbasal nerve plexus (total nerve length per image), corneal sensitivity (assessed
with the Cochet–Bonnet esthesiometer), basic tear secretion (assessed with Schirmer’s I
test with anesthesia) and tear film stability (evaluated by means of tear film break up time
[TFBUT]) were assessed preoperatively and at 1, 3, 6, 9, 12, 18 and 24 postoperative month
time intervals and pre- to postoperative values were compared
Results: In the experimental study a significant dehydration effect of CXL on corneal
buttons after the procedure was demonstrated. In the clinical study of CXL and tPRK-CXL
we found that visual acuity and topography of patients in the tPRK-CXL group were
significantly better than in the CXL group, without compromising postoperative stability up to
three years postoperatively. Effect of CXL as seen in confocal microscopy was deeper in the
tPRK-CXL group. No effect was detected on endothelial cells. Regarding effect on
innervation and tear film, we found total nerve length per image and corneal sensitivity
significantly decreased until the sixth postoperative month. Results of Schirmer’s I test and
TFBUT had no statistically significant difference at any time point.
Conclusions: Corneal dehydration is detected immediately after the CXL procedure. This
phenomenon may contribute to increased mechanical stiffness of the cornea. Simultaneous
tPRK followed by CXL in this series of keratoconus patients offered significantly improved
vision to treated patients in comparison to CXL alone, and similar good results regarding
postoperative stability. A transient decrease in corneal innervation and corneal sensitivity
can be observed up to six months after CXL.
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| Language |
Greek |
| Issue date |
2018-03-28 |
| Collection
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School/Department--School of Medicine--Department of Medicine--Doctoral theses
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Type of Work--Doctoral theses
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| Permanent Link |
https://elocus.lib.uoc.gr//dlib/b/b/7/metadata-dlib-1523946810-190136-15371.tkl
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| Views |
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