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Identifier 000390410
Title Αποτελεσματικότητα και σταθερότητα εφαρμογής υβριδικού φακού επαφής τελευταίας γενιάς σε πρώιμα στάδια μετά από θεραπεία διασύνδεσης κερατοειδικού κολλαγόνου για τη σταθεροποίηση του κερατοκώνου
Alternative Title Effectiveness and stability of fitting of a new hybrid contact lens in early stages after corneal collagen cross linking for keratoconus
Author Μελά, Βασιλική Α.
Thesis advisor Κυμιωνής, Γεώργιος
Reviewer Παλλήκαρης, Ιωάννης
Αστυρακάκης, Νικόλαος
Τσιλιμπάρης, Μιλτιάδης
Abstract Purpose: To evaluate the effectiveness and the stability of fitting of a new hybrid contact lens in early stages after treatment with corneal collagen cross linking for stabilization of keratoconus. Patients and methods: In this prospective and interventional research 14 eyes of 11 keratoconic patients were recruited. The measurements were performed preoperatively and in the 1st, 3rd and 6th month after the treatment. 2 patients didn't complete the study measurements until the 6th postoperative month. The probability of keratoconus (KPI index) was evaluated by corneal topography (system Galilei 5.0). Objective evaluation of the tear film was performed by qualitative (tear break up time test) and quantitative (Schirmer test) measurements. The subjective evaluation was performed by a specific questionnaire (DEQ-5) related to dry eye symptoms. To determine the tolerability of the contact lens, patients rated any sense of discomfort, (on a scale from 1-5) caused by its fitting. The sample of patients was divided into 2 groups, according to the preoperative usage or no of contact lenses. Furthermore, the fitting of the hybrid contact lens Ultrahealth (Synergeyes Inc) was carried out and its parameters (vault, skirt, over refraction sphere) were recorded at each follow-up visit. The fitting of the contact lens was visualized by digital camera (Nikon E4500) which was connected with a slit lamp. The keratometry readings and the residual astigmatism were recorded by automatic refractometer (Canon RK-F1). Finally, the thickness of the tear film was measured by anterior segment optical coherence tomography (system Visante ΟCT 3.0). Results: The mean value of the preoperative uncorrected visual acuity (UVA) and best corrected visual acuity (BCVA), which were 0,71±0,37 logmar and 0,15±0,13 logmar respectively were improved to 0,40±0,28 logmar (p=0,02) in the 1st postoperative month, 0,36±0,27 logmar (p=0,02) in the 3rd month and 0,34±0,29 logmar (p=0,03) in the 6th month for the UVA and to 0,13±0,16 logmar (p=0,18), in the 1st postoperative month, 0,11±0,13 logmar (p=0,02) in the 3rd and 0,12±0,11 logmar (p=0,17) in the 6th month for the BCVA. Mean Ksteep was statistically significant decreased from 48,27±3,07 dpt preoperatively, to 46,07±3,01dpt (p=0,002) in the 1st postoperative month, 45,99±3,00 dpt (p=0,00) in the 3rd month and 46,56±3,12 dpt (p=0,009) in the 6th month. Mean Kflat was decreased from 43,76±2,57 dpt preoperatively to 10 43,28±2,06 dpt in the 1st postoperative month, 42,88±2,09 dpt in the 3rd month and 43,54±2,36 dpt in the 6th month. Statistically significant differences were recorded only in the 3rd postoperative month with p=0,05. The astigmatism was also decreased from 4,75±2,29 dpt preoperatively to 3,20±1,70 dpt in the 1st postoperative month, 3,35±1,83 dpt in the 3rd month and 3,20±1,82 dpt in the 6th month. The differences were statistically significant in all the exam periods (p=0,000). 42,86% (6/14 eyes) had a decrease of 50 or 100μm in the vault value either in the 1st, or in the 3rd postoperative month. 28% (4/14 eyes) had a change in the soft skirt of the contact lens either in the 1st or in the 3rd postoperative month. The mean value of the over refraction sphere showed greater changes in the 1st and 3rd postoperative month, where was recorded an increase of 0,25dpt and 0,50dpt respectively, compared to the preoperative stage. There was not a statistically significant difference between any time intervals. The correlation between the vault change and the ablation depth was weak and positive, with statistically non significant results in all the exam periods. The correlation between the vault change and the change of the minimum thickness of the cornea, as well as the central thickness was negative with also statistically non significant results. Preoperatively the BCVA with the hybrid contact lens was improved at 0,11 logmar (p=0,003), in the 1st postoperative month at 0,09 logmar (p=0,004), in the 3rd month at 0,08 logmar (p=0,007) and in the 6th month at 0,09 logmar (p=0,003), compared to the BCVA achieved by the refraction. The value of the astigmatism that was corrected by the Ultrahealth was 2,93 dpt (p=0,001) preoperatively, 1,49 dpt (p=0,004) in the 1st postoperative month, 1,46 dpt (p=0,003) in the 3rd month and 1,46 dpt (p=0,002) in the 6th month. The results of the objective evaluation of the lacrimal layer showed a statistically significant reduction of the values in the 1st postoperative month (p=0,004 for TBUT and Schirmer test) and statistically significant improvement in the 3rd month (p=0,007 for TBUT and p=0,003 for Schirmer test) compared to the 1st month. High levels of ocular discomfort were recorded by the questionnaire DEQ-5, at the preoperative stage and in the 1st postoperative month, with statistically significant improvement in the 3rd month (p=0,005) and in the 6th month (p=0,003). Correlations of TBUT and Schirmer's test with the BCVA of Ultrahealth was negative in all the exam periods with statistically significant results in the Schirmer's test in the 3rd postoperative month with r=-0,6 and p=0,03. The correlation between the DEQ-5 and the BCVA of Ultrahealth was positive without statistical significance. Contact lens tolerance showed statistically significant 11 improvement in both groups, where p=0,03 for non contact lens users and p=0,01 for contact lens users in the 3rd postoperative month and p=0,02 in both groups in the 6th month. The correlation between the contact lens tolerance and the Schirmer's test was negative in all the exam periods, with statistical significance in the 6th postoperative month r=-0,58 and p=0,02, while with the results of the DEQ-5 was positive preoperatively and in the 1st and 6th postoperative month, without however statistical significance. Conclusions: The Ultrahealth hybrid contact lens improves the visual acuity as well as corrects a value of astigmatism. The postoperative changes of the parameters are multifactorial and additional cases are needed for further investigation of stronger correlations. The 3rd postoperative month is the best period for contact lenses daily use after a surgical treatment such as cross linking, as parameters stability, improvement of tear secretion and quality, as well as improvement of contact lens tolerance were observed.
Language Greek
Subject Collagen cross-linking
Early stages
Hybrid contact lens
Keratoconus
Διασύνδεση κολλαγόνου
Κερατοκώνος
Πρώιμα στάδια
Υβριδικός φακός επαφής
Issue date 2015-03-31
Collection   School/Department--School of Medicine--Department of Medicine--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/d/c/c/metadata-dlib-1428392048-207924-31626.tkl Bookmark and Share
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