Post-graduate theses
Current Record: 5061 of 6563
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| Identifier |
000352318 |
| Title |
Μέτρηση της διαφάνειας του κερατοειδή μετά από διαθλαστικές επεμβάσεις με excimer laser |
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Author
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Πεντάρη, Ηρώ
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Thesis advisor
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Γκίνης, Χαρίλαος
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Reviewer
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Τσιλιμπάρης, Μιλτιάδης
Παλλήκαρης, Ιωάννης
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| Abstract |
Purpose:
Corneal haze is an adverse effect after photorefractive keratectomy (PRK) and is
associated with morphological changes in the cornea. The purpose of this study was
to employ optical and image processing techniques to calculate the intensity and
angular distribution of scattered light in a series of post-PRK rabbit corneas and to
correlate these findings with clinical and histopathological observations.
Methods:
Eight pigmented rabbits underwent PRK (-6D, 6mm OZ). All eyes received local
antibiotic drops until their reepithelialization. The animals were treated in accordance
to the Statement for the Use of Animals in Ophthalmic and Vision Research. A
specialized physician assessed subjective haze of all eyes on a weekly basis, while
central corneal thickness (CCT) was also recorded. Animals were sacrificed at the
tenth postoperative week. The intensity (and angular distribution) of scattered light
was measured for all corneas by means of a purposely-developed camera lens that
incorporated excised rabbit corneas between its glass elements. This lens was used
with a CCD camera to record images projected on a computer screen. The power ratio
of scattered light (SR=Scatter Ratio) was calculated by measuring the intensity of a
dark disk on a uniform bright background. Based on images of a bright semiplane, the
angular distribution of scatter was calculated. After the scatter measurement, the
corneas were prepared for histological examination.
Results:
All measured parameters exhibited symmetry between fellow eyes. Maximum
subjective haze grade (2.18±0.99) was observed at week 4 and minimum (0.92±0.93)
at week 10. CCT did not change significantly postoperatively. SR was increased in all
eyes in respect to previously measured intact corneas while ten eyes exhibited no
subjective haze. Histology revealed a characteristic subepithelial irregular layer
similar to scar tissue. SR was correlated to the thickness of this layer. The angular
distribution of scattered light was characterized by a narrow forward peak (1.5
degrees FWHM).
Conclusions:
Forward scatter following PRK can be attributed mainly to the subepithelial irregular
layer. The angular distribution of scatter is in accordance to the size of structures
observed microscopically in this layer. The optical technique was more sensitive than
the subjective. The presented methodology may prove useful for the evaluation of
different treatment schemes in terms of postoperative corneal haze.
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| Physical description |
76 σ. : πιν. ; 30 εκ. |
| Language |
Greek |
| Subject |
Cornea |
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Ophthalmology |
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Refraction, Ocular |
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Refractive Surgical Procedures |
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Διάθλαση, Οφθαλμική |
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Κερατοειδής |
| Issue date |
2008-12-15 |
| Collection
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School/Department--School of Medicine--Department of Medicine--Post-graduate theses
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Type of Work--Post-graduate theses
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| Notes |
Διατμηματικό μεταπτυχιακό πρόγραμμα σπουδών: "Οπτική και Όραση" |
| Permanent Link |
https://elocus.lib.uoc.gr//dlib/f/5/9/metadata-dlib-e47fb3d7dbec01bcd0a8c5adffcbe3f0_1261981473.tkl
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| Views |
205 |
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