Publications by authors named "Vassilios P Kozobolis"

56 Publications

Optical coherence tomography biomarkers for visual acuity in patients with idiopathic epiretinal membrane.

Eur J Ophthalmol 2020 Dec 14:1120672120980951. Epub 2020 Dec 14.

Vitreoretinal and Uveitis Department, Ophthalmica Clinic, Thessaloniki, Greece.

Purpose: To investigate the correlation between outer and inner retina optical coherence tomography (OCT) biomarkers and visual acuity in patients with idiopathic epiretinal membrane (iERM) and identify which of them may be predictive of visual function.

Methods: A retrospective cross-sectional single-center study was conducted that included patients diagnosed with iERM. Spectral domain OCT images were obtained and assessed qualitatively and quantitatively. The association of OCT parameters with best corrected visual acuity was analyzed.

Results: Charts of 97 eyes of 97 patients were reviewed. Central foveal thickness, maximal retinal thickness (MRT), photoreceptor outer segment length, outer foveal thickness, ganglion cell-inner plexiform layer complex thickening, inner retinal thickness and inner retinal layer irregularity index were among the major outcome measures. OCT scans were also assessed for the presence of cotton ball sign, ellipsoid zone disruption, ectopic inner foveal layer, disorganization of retinal inner layers (DRIL), intraretinal fluid, subretinal fluid (SRF) and epimacular membrane rip. Univariate analysis showed statistically significant association between all the aforementioned parameters with worse vision, except for cotton ball sign and SRF. Multivariate analysis found that MRT and severe DRIL were strongly correlated with worse vision ( < 0.001).

Conclusion: MRT and severe DRIL should be considered as negative prognostic factors for visual acuity.
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http://dx.doi.org/10.1177/1120672120980951DOI Listing
December 2020

A Critical Overview of the Biological Effects of Mitomycin C Application on the Cornea Following Refractive Surgery.

Adv Ther 2019 04 11;36(4):786-797. Epub 2019 Mar 11.

Clínica Novovisión, Madrid, Spain.

During the last 2 decades, modifying the shape of the cornea by means of laser photoablation has emerged as a successful and popular treatment option for refractive errors. Corneal surface ablation techniques such as photorefractive keratectomy (PRK) and laser-assisted subepithelial keratomileusis (LASEK) offer good refractive results while having a minimal impact on corneal biomechanical stability. Past limitations of these techniques included the long-term regression of refractive outcome and a vigorous healing response that reduced corneal clarity in some patients (giving rise to what is clinically described as "haze"). Mitomycin C (MMC) was introduced as a healing modulator and applied on the corneal surface after refractive surgery to address these drawbacks. This article critically reviews the available evidence on the biological effects, safety, and clinical benefits of the off-label use of MMC in corneal refractive surgery.
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http://dx.doi.org/10.1007/s12325-019-00905-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6824355PMC
April 2019

Retrobulbar hemodynamics and aqueous humor levels of endothelin-1 in exfoliation syndrome and exfoliation glaucoma.

Clin Ophthalmol 2018 2;12:1199-1204. Epub 2018 Jul 2.

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis, Greece,

Background: Endothelin-1 (ET-1) is the most potent vasoconstrictor in the body. There are reports in the literature correlating plasma levels of ET-1 and its impact on retrobulbar hemodynamics. This study evaluates aqueous humor levels of ET-1 and retrobulbar hemodynamics in patients with exfoliation syndrome (XFS) and exfoliation glaucoma (XFG).

Patients And Methods: Patients scheduled for cataract surgery were included. Patients were allocated to non-exfoliation non-glaucoma group (controls), XFG and XFS groups. Peak systolic velocity (PSV), end diastolic velocity, and resistivity index of the ophthalmic artery (OA), short posterior ciliary arteries, and central retinal artery (CRA) were determined preoperatively using color Doppler imaging. Aqueous humor samples obtained at the beginning of cataract surgery were analyzed with enzyme-linked immunosorbent assay.

Results: Sixty-nine participants of similar age were included (controls: n=24, XFG: n=22, XFS: n=23). Multiple regression analysis showed that ET-1, OA-PSV, OA-resistivity index, CRA-PSV, and CRA-end diastolic velocity were influenced by group but not by sex or age. ET-1 for the XFG group (15.93±2.8 pg/mL) was significantly higher than for the XFS (8.92±2.7 pg/mL) and control (8.44±2.6 pg/mL) groups. The difference in ET-1 titers between the control and XFS groups was not statistically significant. All four hemodynamic parameters affected by group status significantly correlated with ET-1 levels in eyes with XFS. In eyes with XFG, two of the four hemodynamic parameters significantly correlated with ET-1 levels. In control eyes, no correlation between ET-1 and hemodynamic parameters affected by group status was detected.

Conclusion: ET-1 aqueous levels in eyes with XFG were significantly higher than those of age-matched controls. Reduced blood flow and increased vascular resistivity were detected in the OA and the CRA in eyes with XFG/XFS. ET-1 levels in eyes with XFG/XFS exhibit a significant correlation with hemodynamic parameters that indicate reduced perfusion.
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http://dx.doi.org/10.2147/OPTH.S155551DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6033085PMC
July 2018

A systematic review of teleophthalmological studies in Europe.

Int J Ophthalmol 2018 18;11(2):314-325. Epub 2018 Feb 18.

Department of Ophthalmology, University Hospital of Alexandroupolis, Dragana, Alexandroupolis 68100, Greece.

A systematic review of the recent literature regarding a series of ocular diseases involved in European telemedicine projects was performed based on the PubMed, Google Scholar and Springer databases in June 2017. Literature review returned 44 eligible studies; among them, emergency ophthalmology, diabetic retinopathy, glaucoma, age-related macular disease, cataract and retinopathy of prematurity. The majority of studies indicate teleophthalmology as a valid, reliable and cost-efficient method for care-provision in ophthalmology patients which delivers comparable outcomes to the traditional examination methods.
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http://dx.doi.org/10.18240/ijo.2018.02.22DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5824090PMC
February 2018

A systematic review of pseudophakic monovision for presbyopia correction.

Int J Ophthalmol 2017 18;10(6):992-1000. Epub 2017 Jun 18.

Department of Ophthalmology, University Hospital of Alexandroupolis, Dragana, Alexandroupolis 68100, Greece.

A systematic review of the recent literature regarding pseudophakic monovision as a reliable methods for presbyopia correction was performed based on the PubMed, MEDLINE, Nature and the American Academy of Ophthalmology databases in July 2015 and data from 18 descriptive and 12 comparative studies were included in this narrative review. Pseudophakic monosvision seems to be an effective method for presbyopia with high rates of spectacles independence and minimal dysphotopsia side-effects, that should be considered by the modern cataract surgeons.
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http://dx.doi.org/10.18240/ijo.2017.06.24DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5515155PMC
June 2017

Evaluation of activities of daily living following pseudophakic presbyopic correction.

Eye Vis (Lond) 2017 19;4. Epub 2017 Jan 19.

Department of Ophthalmology, University Hospital of Alexandroupolis, 68100 Dragana, Alexandroupolis, Greece.

Background: Pseudophakic presbyopic correction is among the prevalent methods for regaining near vision capacity. The purpose of this study is to compare the impact of pseudophakic monovision correction and multifocal lens implantation on the performance in a series of activities of daily living (ADL) of presbyopic patients.

Methods: An ADL research framework (10 ADLs) was constructed and validated in a sample of patients divided into three validation groups according to their near visual acuity. Sixty-two participants that underwent mini-monovision (MoG) cataract extraction and 60 that underwent bilateral multifocal lenses implantation (MfG) populated study groups and addressed the ADLs. Binocular uncorrected distant (BdUVA) and near (BnUVA) visual acuity were associated with ADL scores and with subjective satisfaction using the VF-14 questionnaire.

Results: Test-retest reliability [all Intraclass Correlations Coefficients (ICC) >0.90] and construct validity (all  < 0.05) tests indicated sufficient psychometric performance of the ADL framework. Both study groups presented comparable mean ADL scores ( = 0.07) however, MoG patients had lower performance in demanding ADLs ( = 0.02). ADL scores demonstrated significant correlation with BnUVA (r = -0.67,  < 0.01) VF-14 scores (r = 0.53,  < 0.01).

Conclusions: Both methods provide sufficient near vision capacity for the majority of activities of daily living. However, only multifocal lens implantation can address demanding near vision tasks.

Trial Registration: ClinicalTrials.gov Identifier: NCT02431156.
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http://dx.doi.org/10.1186/s40662-016-0067-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5244730PMC
January 2017

Impact of corneal cross-linking combined with photorefractive keratectomy on blurring strength.

Clin Ophthalmol 2016 1;10:571-6. Epub 2016 Apr 1.

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis, Greece; Eye Institute of Thrace, Alexandroupolis, Greece.

Purpose: The aim of this study was to evaluate the impact of corneal cross-linking combined with photorefractive keratectomy (PRK) on blurring strength.

Methods: A total of 63 patients with keratoconus were recruited for this study, and two study groups were formed according to the therapeutic intervention: corneal collagen cross-linking (CxL) group (33 patients) received corneal cross-linking according to the Dresden protocol, while the rest additionally received topography-guided photorefractive keratectomy (tCxL). The impact of surgical procedure on blurring strength was assessed by power vector analysis. Potential association between blurring strength and vision-specific quality of life was assessed using the National Eye Institute Visual Function Questionnaire (NEI-VFQ) 25 instrument.

Results: Blurring strength presented excellent correlation with NEI-VFQ scores both preoperatively and postoperatively (all P<0.01). Both groups demonstrated nonsignificant changes in best-corrected visual acuity; however, only the tCxL group had significant reduction in blurring strength (13.48+10.86 [preoperative], 4.26+7.99 [postoperative], P=0.042).

Conclusion: Only the combined treatment (tCxL) resulted in significant reduction in blurring strength. Moreover, the excellent correlation of blurring strength with NEI-VFQ scores indicates its reliability as an index of self-reported quality of life in keratoconus, since it seems to address the nonsignificant changes in best-corrected visual acuity following CxL treatments that are conceived as subjective improvement by the patient.
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http://dx.doi.org/10.2147/OPTH.S100770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4824379PMC
April 2016

Liquefaction for cataract extraction.

Int J Ophthalmol 2016 18;9(2):306-11. Epub 2016 Feb 18.

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis 68100, Greece; Eye Institute of Thrace, Democritus University, Alexandroupolis 68100, Greece.

A systematic review of the recent literature regarding the implementation of the liquefaction in cataract surgery and its short-term and long-term outcomes in various parameters that affect the quality of patients' life, including visual rehabilitation and possible complications was performed based on the PubMed, Medline, Nature and the American Academy of Ophthalmology databases in November 2013 and data from 14 comparative studies were included in this narrative review. Liquefaction is an innovative technology for cataract extraction that uses micropulses of balanced salt solution to liquefy the lens nucleus. Most studies reported that liquefaction is a reliable technology for mild to moderate cataracts, while fragmentation difficulties may be encountered with harder nuclei.
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http://dx.doi.org/10.18240/ijo.2016.02.24DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4761748PMC
March 2016

Variability of different reference bodies in normal, keratoconus, and collagen crosslinked corneas.

Eur J Ophthalmol 2015 Nov-Dec;25(6):468-73. Epub 2015 May 20.

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis - Greece.

Purpose: To evaluate the reproducibility of different Scheimpflug imaging-derived reference bodies in normal, keratoconus (KC), and crosslinked (CXL) eyes.

Methods: In this prospective, observational study, 40 participants populated the control group (CG), while 33 and 34 patients formed the KC group and the CXL group, respectively. One eye was randomly selected when both were eligible. Elevation measurements were obtained using Scheimpflug camera, by applying the following reference bodies: the best fit sphere (BFS), the best fit toric ellipsoid (BFTE), the best fit toric ellipsoid with fixed eccentricity of 0.4 (BFTEF), the best fit ellipsoid (BFE), and the best fit torus, by 2 operators in 2 sessions. The variability of different reference bodies' parameters was assessed using intraclass correlation coefficient (ICC).

Results: Differences between operators were nonsignificant for all reference bodies' parameters in all study groups (p>0.1). Regarding CG, BFS for both operators and BFTE for operator 1 presented the best intrasession repeatability (majority of ICCs >0.90), while average interobserver reliability was recorded for the majority of reference bodies' parameters. Regarding KC and CXL groups, BFS, BFTEF, and BFE reference bodies demonstrated the best intrasession and interobserver reproducibility (majority of ICCs >0.90) for both groups. Steep and flat radius parameters presented the best overall reproducibility, with the majority of ICCs for all reference bodies ranging above 0.90, in all study groups.

Conclusions: High variability was encountered for most reference surfaces. Ellipsotoric surfaces presented acceptable repeatability in KC and post-CXL corneas.
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http://dx.doi.org/10.5301/ejo.5000621DOI Listing
February 2016

Lacrimal outflow mechanisms and the role of scintigraphy: current trends.

World J Nucl Med 2014 Jan;13(1):16-21

Department of Ophthalmology, University Hospital of Alexandroupolis, Greece.

Lacrimal outflow can be compromised by anatomical obstructions or stenoses (nonfunctional epiphora) or by defective lacrimal "pump" function (functional epiphora). Although classic imaging modalities, such as X-ray dacryocystography, computed tomography, or magnetic resonance imaging can effectively evaluate the former, their success is much less in the evaluation of the latter. This is largely due to the fact that forced diagnostic injection of fluid into the canalicular system can overcome partial obstruction sites. On the other hand, lacrimal scintigraphy mimicks "physiological" lacrimal outflow, being performed under pressure gradients present in everyday life. This is why it is considered more suitable for the study of functional epiphora. Furthermore, quantitative lacrimal scintigraphy (with time-activity curves) enables the accurate measurement of lacrimal clearance from the conjunctival fornices and may be used to study the physiology of the lacrimal "pump." Data obtained from the scintigraphic study of lacrimal outflow may be used to design more effective procedures in the management of functional and nonfunctional epiphora. This is a review article, based on a literature search with emphasis on recent publications and on those supporting interdisciplinary cooperation between ophthalmology and nuclear medicine.
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http://dx.doi.org/10.4103/1450-1147.138569DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4149763PMC
January 2014

Mini-monovision versus multifocal intraocular lens implantation.

J Cataract Refract Surg 2015 Jan 21;41(1):53-7. Epub 2014 Jun 21.

From the Department of Ophthalmology (Labiris, Patsiamanidi, Kozobolis), University Hospital of Alexandroupolis and the Eye Institute of Thrace (Labiris, Giarmoukakis, Papadopoulos, Kozobolis), Alexandroupolis, Greece.

Purpose: To compare the effect of monovision correction and multifocal intraocular lens (IOL) implantation on patient satisfaction, spectacle dependence, visual acuity, and dysphotopsia in cataract patients.

Setting: University Hospital of Alexandroupolis, Democritus University of Thrace, Alexandroupolis, Greece.

Design: Prospective randomized trial.

Methods: Patients with a diagnosis of senile cataract with stage 2 nuclear opalescence were randomly assigned to 2 groups: monovision and multifocal IOL implantation. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, Visual Function Index-14 (VF-14) scores, and spectacle dependence were assessed prior to surgery and 6 months postoperatively.

Results: The monovision group comprised 38 patients and the multifocal IOL implantation group, 37 patients. Both techniques provided excellent refractive outcomes in UDVA and VF-14 scores (all P < .01). No significant intergroup differences were detected in VF-14 scores at the final postoperative examination. The monovision group patients presented significantly more spectacle dependence for near vision but less glare.

Conclusions: Monovision and multifocal IOL implantation provided excellent refractive outcomes for distance vision. Multifocal IOL insertion was associated with less dependence on glasses overall but significantly more dysphotopsia.

Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.
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http://dx.doi.org/10.1016/j.jcrs.2014.06.015DOI Listing
January 2015

Corneal collagen cross-linking in a late-onset graft infectious ulcer: a case report.

J Med Case Rep 2014 Jun 6;8:180. Epub 2014 Jun 6.

Department of Ophthalmology, University Hospital of Alexandroupolis, 68100 Dragana, Alexandroupolis, Greece.

Introduction: Infectious keratitis following penetrating keratoplasty is a common postoperative complication. Intensive topical and systemic treatments do not always prevent the risk of graft failure. In this report we demonstrate the beneficial anti-microbial effect of corneal collagen cross-linking in a late-onset, sight-threatening, corneal graft ulcer.

Case Presentation: A 57-year old Caucasian man underwent penetrating keratoplasty in his left eye, due to corneal bullosa after cataract extraction surgery. Twelve months after the penetrating keratoplasty, he visited our emergency service complaining of burning and foreign body sensation in his operated eye. Slit-lamp examination revealed a central, round-shaped ulcer of the graft. Due to poor response to the intensive topical antibiotic therapy, corneal collagen cross-linking was applied 3 days after admission, in an attempt to control the infection. Cultures indicated the predominance of methicillin-resistant Staphylococcus aureus infection. Five days after corneal collagen cross-linking treatment, the epithelium was completely re-epithelized, while the transparency of the transplanted cornea was gradually restored within the 12-month follow-up period. No relapses occurred.

Conclusion: Corneal collagen cross-linking seems to be a safe and effective therapeutic alternative in resistant cases of infectious keratitis following penetrating keratoplasty.
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http://dx.doi.org/10.1186/1752-1947-8-180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4070638PMC
June 2014

Patient satisfaction and spectacle independence with the iSert multifocal lens.

Eur J Ophthalmol 2015 Feb 12;25(2):e1-2. Epub 2015 Feb 12.

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis - Greece.

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http://dx.doi.org/10.5301/ejo.5000492DOI Listing
February 2015

Tissue inhibitor of metalloproteinase 4 in aqueous humor of patients with primary open angle glaucoma, pseudoexfoliation syndrome and pseudoexfoliative glaucoma and its role in proteolysis imbalance.

BMC Ophthalmol 2013 Nov 8;13:69. Epub 2013 Nov 8.

Department of Ophthalmology, Democritus University of Thrace, Alexandroupolis, Greece.

Background: To quantify the levels of tissue inhibitor of metalloproteinase 4 (TIMP4) and its ratios with free metalloproteinases (MMP) in the aqueous humor of patients with primary open angle glaucoma (POAG), pseudoexfoliation syndrome (PXS) and pseudoexfoliative glaucoma (PXG) and to evaluate a possible imbalance between MMPs and TIMPs in these samples.

Methods: Free MMP2, MMP3, MMP9, TIMP1, TIMP2, TIMP4 concentrations and active levels of MMP2 and MMP3 were determined with immunoassay ELISA and activity assay kits in 168 aqueous samples.

Results: TIMP4 was elevated in glaucoma patients(POAG: 0.95 ± 0.49 PXG: 1.28 ± 1.38 pg/ml. p < 0.001). POAG, PXS and PXG samples demonstrated higher MMP2, TIMP1 and TIMP2 concentrations (p < 0.001). Samples from the PXS and PXG groups had a lower total/active MMP2 ratio (p < 0.004 and p < 0.008 respectively). Stoichiometric analysis showed an overbalance of TIMPsover MMPs in both POAG & PXG groups,especially of TIMP4.

Conclusion: TIMP4 elevation is a novel finding in glaucomatous eyes. A disregulation of extracellular matrix homeostasis is suggested in POAG, PXS and PXG.
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http://dx.doi.org/10.1186/1471-2415-13-69DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3828421PMC
November 2013

An overview of corneal collagen cross-linking (CXL).

Adv Ther 2013 Oct 30;30(10):858-69. Epub 2013 Oct 30.

Faculty of Medicine, Institute of Vision and Optics, University of Crete, Heraklion, Greece.

Corneal collagen cross-linking (CXL) was first described over a decade ago and is now considered to be one of the most important surgical innovations of modern ophthalmology. Prior to its introduction, no interventions were available to arrest, or slow down ectatic disease progression, with corneal transplantation required in the majority of cases. Unlike earlier treatments of corneal ectasias that attempted to only improve the consequences of the disease, CXL aims to address the corneal biomechanical weakening itself. The long-term safety and efficacy of CXL have been established in several studies that have documented significant improvements in all outcome measures (visual acuity, spherical equivalent, astigmatism, and keratometric findings). The emerging combination of CXL with other interventions (termed 'CXL plus') optimizes the visual and topographic outcomes. This, along with the expansion of the techniques' indications for other clinical conditions, such as microbial keratitis, highlights the continuous improvement of the initial technique and confirms its wide acceptance. Overall, CXL has already demonstrated much promise and has several clinical indications, representing a clear example of recent advances in ocular therapy.
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http://dx.doi.org/10.1007/s12325-013-0065-9DOI Listing
October 2013

Liquefaction versus torsional IP: a comparative study on endothelial cells, corneal edema and corneal sensitivity.

Ophthalmic Res 2013 23;49(1):37-42. Epub 2012 Oct 23.

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis, Greece.

Background/aims: To compare the impact of liquefaction and torsional IP cataract extraction methods on endothelial cell count (ECC), central corneal edema, and central corneal sensitivity (CCS) in a sample of cataract patients.

Methods: The liquefaction (LG) and torsional IP (TG) group consisted of 47 and 48 grade 2 cataract eyes, respectively. Uncorrected and best spectacle-corrected visual acuity, ECC, central corneal thickness (CCT), and CCS were measured 1 day prior to surgery, 10 days, 1 and 3 months postoperatively.

Results: Significant difficulties in the nucleus fragmentation were encountered in 2 LG eyes, and they were excluded from the study. Both techniques provided excellent refractive outcomes (LG, p < 0.001; TG, p = 0.02). Nonsignificant differences were detected in CCT values at the final postoperative examination; however, TG patients presented higher CCT on the first postoperative day (p = 0.04). Both groups presented comparable significant reductions in ECC (LG, p < 0.001; TG, p < 0.001) and CCS (LG, p = 0.02; TG, p = 0.02).

Conclusion: Both methods provide excellent refractive outcomes, with comparable impact on ECC and CCS. Liquefaction seems to provide less corneal edema; however, difficulties in nucleus fragmentation may be encountered even in grade 2 cataracts.
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http://dx.doi.org/10.1159/000342974DOI Listing
May 2013

Variability in Scheimpflug image-derived posterior elevation measurements in keratoconus and collagen-crosslinked corneas.

J Cataract Refract Surg 2012 Sep;38(9):1616-25

Ophthalmology Department, University Hospital of Alexandroupolis, 68100 Dragana, Alexandroupolis, Greece.

Purpose: To determine the variability in Scheimpflug image-derived posterior elevation measurements in eyes with keratoconus or corneal collagen crosslinking (CXL).

Setting: Eye Institute of Thrace, Alexandroupolis, Greece.

Design: Prospective observational study.

Methods: Two operators in 2 sessions obtained posterior elevation measurements using the Pentacam Scheimpflug system. Variability in measurements was assessed using Bland-Altman analysis and intraclass correlation coefficients (ICCs). Measurements were associated with a series of Scheimpflug-derived keratoconus indices using the Pearson correlation and multivariate linear-regression analysis.

Results: Mean interobserver differences for the central elevation point (e1) and the highest elevation point (HEP) in the keratoconus group were -0.9 μm (95% limits of agreement [LoA], 5.7 to -7.5 μm) and 1.7 μm (95% LoA, 26 to -22.6 μm), respectively. In the CXL group, the mean differences were 0.2 μm (95% LoA, 6.0 to -5.5 μm) and -6.1 μm (95% LoA, 16.8 to -29 μm), respectively. The ICC values in the keratoconus group were satisfactory for most elevation points; the ICC values were unsatisfactory for a series of points in the lower corneal hemisphere. The ICC values for points in both hemispheres were unsatisfactory in the CXL group; HEP had adequate reproducibility. The e1 and HEP parameters correlated significantly with most Scheimpflug-derived indices (P<.05) in the keratoconus group but not in the CXL group. Regression analysis indicated that the central keratoconus index was the primary determinant of the variability in keratoconus eyes.

Conclusions: Scheimpflug-derived posterior elevation measurements had acceptable reproducibility in keratoconus eyes and post-CXL eyes. Less consistent measurements were obtained in the lower hemisphere.
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http://dx.doi.org/10.1016/j.jcrs.2012.04.039DOI Listing
September 2012

Tonography assessment using quantitative and qualitative analysis of the aqueous humor outflow mechanism.

Eur J Ophthalmol 2012 Sep-Oct;22(5):726-33

Department of Ophthalmology & Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, Greece.

Purpose: To perform qualitative evaluation of the aqueous humor (AH) outflow mechanism in glaucoma and nonglaucoma patients by means of tonography assessment and mathematical analysis.

Methods: Sixty-two primary open angle and 58 pseudoexfoliation glaucoma patients were recruited in a non-interventional, observational study between 2004 and 2007. Qualitative and quantitative outflow assessment was acquired by means of a digital tonographer and mathematical analysis. Qualitative results were represented using slope analysis of the change of the AH outflow rate over the tonography study. The results were compared to the control group (CG; n=100) as well as to a pseudoexfoliation group (PEX; n=46).

Results: Regarding quantitative analysis, glaucoma groups exhibited significantly lower outflow facility compared to nonglaucoma ones (p<0.001). Outflow facility value was significantly correlated to cup to disc ratio (Pearson correlation r=-0.3, p<0.001). Regarding qualitative analysis, the primary open-angle glaucoma (POAG) group presented a significant profile variation at the beginning of the tonography, expressed as an increased resistance of the AH outflow. Both glaucoma groups exhibited profile stabilization at the end of the measurement, suggesting that the outflow rate remained constant, while nonglaucoma groups followed a continuous reduction of the AH outflow rate throughout the study.

Conclusions: The POAG, PXG, PEX, and CG groups demonstrated both qualitative and quantitative tonographic profile differences. The observed differences in the glaucoma groups suggest a distinct pathomechanism between POAG and PXG. It is suggested that POAG patients have a temporary disruption of the AH flow pathway, while PXG patients have a generalized increased flow resistance.
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http://dx.doi.org/10.5301/ejo.5000107DOI Listing
December 2012

A proposed methodology for the assessment of glaucoma awareness in Greece: introduction of the EIT-8G scale.

Eur J Ophthalmol 2012 Jan-Feb;22(1):95-103

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis, Greece.

Purpose: To develop a reliable and practical questionnaire for glaucoma awareness and evaluate the impact of potential determinants.

Methods: Patients with primary open-angle, pigmentary, and exfoliation glaucoma, as well as healthy controls, were recruited. The instrument included questions about demographic characteristics, as well as 8 questions assessing the participant's familiarity with glaucoma. Rasch analysis was used for the validation of the questionnaire. The effect of demographics as potential determinants of awareness was examined with a multivariate logistic regression analysis. Bonferroni-corrected statistical significance was tested with the Mann-Whitney U test or one-way analysis of variance. Association between demographics and questionnaire scores was examined with Spearman correlation.

Results: As indicated by power analysis, responses from 175 patients (mean age 65.5 years) and 314 controls (mean age 43.3 years) were analyzed. Rasch analysis indicated no multidimensionality and good item-person targeting. Mean ± SD awareness scores for the glaucoma and control groups were 4.43 ± 2.10 and 4.20 ± 2.11, respectively (p=0.207). Sex and residence were not predictors of disease awareness, whereas educational level was only a determinant in the control group (p<0.001). Income was a predictor only for patients (r=0.357, p<0.001), whereas family history was predictive for both groups (p<0.001). Logistic regression analysis revealed that only family history was associated with increased awareness (Chi(2)=4.61, p=0.03, odds ratio 1.98).

Conclusions: This study introduces a practical and valid instrument for the assessment of glaucoma awareness.
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http://dx.doi.org/10.5301/EJO.2011.8375DOI Listing
February 2012

Laser in situ keratomileusis flap-thickness predictability with a pendular microkeratome.

J Cataract Refract Surg 2011 Dec 13;37(12):2160-6. Epub 2011 Oct 13.

Department of Ophthalmology & Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, Greece.

Purpose: To assess flap-thickness predictability with a pendular microkeratome (130 μm head).

Setting: Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, Greece.

Design: Clinical trials.

Methods: The study comprised 263 eyes (132 patients). Laser in situ keratomileusis was performed using the 130 μm head of the Carriazo pendular microkeratome; right eyes were treated first. Ultrasound pachymetry and topography were used for central corneal thickness (CCT) and keratometry (K) measurements. Evaluation included flap thickness, flap diameter, and flap shape.

Results: The mean flap thickness was 125 μm ± 22 (SD) (range 74 to 187 μm) in right eyes and 112 ± 21 μm (range 61 to 190 μm) in left eyes. Flap thickness was significantly correlated with preoperative CCT (r = 0.271; P<.001) but not with K values or the manifest refraction spherical equivalent (P>.15). Right eyes had thicker flaps than left eyes (P<.001); both were significantly below the 130 μm head thickness (mean flap thickness 119.2 ± 22.8 μm; P<.001). The mean achieved flap diameter was 9.2 mm using the 9.0 ring and 9.8 mm using the 10.0 mm ring. Flap-thickness stabilization and convergence between right eyes and left eyes occurred after 100 consecutive flap cuts.

Conclusions: Flap-thickness predictability was influenced by preoperative CCT only. All cuts were significantly thinner than the head thickness regardless of the suction ring size. Second surgical eyes had thinner flaps, possibly from blade deterioration from the first cut. Approximately 100 flaps were required as a learning curve.
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http://dx.doi.org/10.1016/j.jcrs.2011.05.044DOI Listing
December 2011

Psychometric properties of the Greek NEI-RQL-42.

Eur J Ophthalmol 2012 May-Jun;22(3):466-76

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis, Greece.

Purpose: To evaluate the psychometric properties of the Greek National Eye Institute Refractive Error Quality of Life Questionnaire (NEI-RQL-42).

Methods: We developed the Greek version of the instrument using forward and backward translation. To examine reliability, Cronbach alpha for each subscale was used as an index of internal consistency. Test-retest reliability was evaluated with intraclass correlation coefficients (ICC). Regarding construct validity, both convergent and discriminant validities were calculated by means of multi-trait analysis. Furthermore, the instrument was evaluated by Rasch analysis, as well.

Results: Three patient groups were studied (emmetropes (n = 20), myopes (n = 41), and hyperopes (n = 18)). Emmetropes scored significantly better in the majority of subscales, while myopes scored better than hyperopes in clarity of vision (p = 0.012), near vision (p<0.001), and satisfaction with correction (p = 0.001). Cronbach alpha ranged from 0.490 (glare) to 0.948 (expectations), with most subscales having high internal consistency. The ICCs ranged from 0.76 to 0.93 for all subscales. All items passed the convergent and discriminant validity tests. Strong correlations were detected between uncorrected visual acuity and near vision, expectations, activity limitations, dependence on correction, worry, and suboptimal correction subscales. Rasch analysis revealed potential weaknesses of the instrument that are associated with the assumptions of the model itself. Specifically, 3 items and 17.5% of the participants fell outside the tolerance box. Moreover, principal component analysis indicated average unidimensionality for the instrument.

Conclusions: Traditional validation methods indicate that the Greek NEI-RQL-42 scale has adequate psychometric properties for comparative studies in local populations. Rasch analysis indicates significant misfits to the model that should be taken into consideration and evaluated in future studies. These misfits might reflect inherent weaknesses of the original NEI-RQL-42 and not of its adaptation to Greek norms.
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http://dx.doi.org/10.5301/ejo.5000062DOI Listing
July 2012

Evaluation of the difference between intended and measured ablation and its impact on refractive outcomes of the wavefront optimize profile and the S001 Wellington nomogram in myopic spherocylindrical corrections.

Clin Exp Ophthalmol 2012 Mar;40(2):127-33

Department of Ophthalmology, University Hospital of Alexandroupolis, Greece.

Background: To evaluate the level of agreement between intended and measured ablation of the wavefront optimize profile corrected by the Wellington nomogram in myopic spherocylindrical corrections and assess its impact on refractive outcomes.

Design: Prospective, university-institute setting.

Participants: Eighty-six participants (86 eyes for photorefractive keratectomy group) and 86 participants (86 eyes for laser in situ keratomileusis group) recruited in a consecutive-if -eligible basis.

Methods: Differences between intended and measured ablation were evaluated with Scheimpflug camera. Refractive outcomes were evaluated by means of postoperative spherical equivalent, postoperative defocus equivalent, contrast sensitivity, correction index, difference vector and index of success.

Main Outcome Measures: Correlation of visual outcomes with intended ablation.

Results: Both groups demonstrated significant over-ablations (16.7±8.5, P<0.001 & 11.8±18.5, P<0.001, respectively). Intended ablation was the primary determinant of the measured difference (r-square 0.769 & 0.765, respectively). Photorefractive keratectomy corrections over 100µ had significant impact on postoperative spherical equivalent, postoperative defocus equivalent, correction index, difference vector and index of success (P=0.044, P=0.05, P=0.019, P=0.016, P=0.006, respectively), but laser in situ keratomileusis corrections over 100µ had significant impact only on postoperative defocus equivalent, difference vector and index of success (P=0.04, P=0.05).

Conclusions: The results suggest that the wavefront optimize profile seems to over-ablate corneal tissue both in photorefractive keratectomy and laser in situ keratomileusis. Over-ablation exerts significant impact on refractive outcomes only in high spherocylindrical corrections.
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http://dx.doi.org/10.1111/j.1442-9071.2011.02633.xDOI Listing
March 2012

Tonometry in keratoconic eyes before and after riboflavin/UVA corneal collagen crosslinking using three different tonometers.

Eur J Ophthalmol 2012 Mar-Apr;22(2):142-52

Eye Institute of Thrace and Department of Ophthalmology, Democritus University of Thrace, Alexandroupolis, Greece.

Purpose: To evaluate the Goldmann applanation tonometer (GAT), the Pascal dynamic contour tonometer (PDCT), and the ocular response analyzer (ORA) tonometer in measuring intraocular pressure (IOP) in keratoconic eyes before and after riboflavin/ultraviolet A corneal collagen crosslinking (CXL), to assess agreement among devices and to analyze the impact of some ocular parameters on their measurements.

Methods: Fifty keratoconic eyes were included. Intraocular pressure was measured with GAT, PDCT, and ORA before and after CXL. Fifty nonkeratoconic eyes served as controls. Device agreements were calculated by Bland-Altman analysis. The effect of some ocular characteristics on IOP measurement differences between tonometers was determined.

Results: Between the 2 groups, there were statistically significant differences in all examined parameters. Preoperatively, in both groups a statistically significant difference was found in IOP measurements among devices (p<0.05). Bland-Altman analysis showed a bias among devices. On average, PDCT overread GAT and ORA. The IOP measurement differences were better predicted by corneal resistance factor. Postoperatively, in keratoconus eyes, there was no statistically significant difference in IOP measurements among the 3 tonometers (p>0.05). The IOP readings with all tonometers after treatment were higher than those obtained preoperatively; however, not to a statistically significant level, with the exception of PDCT and ORA readings at the first month postoperatively. Corneal resistance factor measurements have no significant change after CXL.

Conclusions: Pascal dynamic contour tonometer could provide more consistent and closer to the true IOP readings than GAT and ORA in healthy eyes with corneal thickness outside the 520-550 µm range, in keratoconus patients and after CXL. Corneal resistance factor was associated significantly with agreement among devices.
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http://dx.doi.org/10.5301/EJO.2011.8328DOI Listing
August 2012

Autophagy patterns and prognosis in uveal melanomas.

Mod Pathol 2011 Aug 15;24(8):1036-45. Epub 2011 Apr 15.

Department of Pathology, Democritus University of Thrace Medical School, Alexandroupolis, Greece.

Autophagy is a self-degradation mechanism by which cells recycle their own cytoplasmic constituents. It has been claimed that, under certain conditions, such a process may be associated with tumor progression. In this study, the autophagic activity was investigated in a series of 99 uveal melanomas after immunohistochemical staining for the autophagy-associated proteins MAP1LC3A and BECN1, most commonly known as LC3A and Beclin 1, respectively. These were assessed in parallel with the hypoxia-inducible factor 1α (HIF1A) and its downstream protein lactate dehydrogenase 5 (composed by five LDHA subunits). Increased autophagic reactivity, detected by MAP1LC3A or BECN1, was associated with intense pigmentation and tumor hypoxia. Uveal melanomas with extensive overexpression of BECN1 or those with underexpression of this protein were associated with the worst prognosis, but the former manifested metastases much earlier than the latter; only 58% of patients with extensive BECN1 overexpression were alive at 4 years, compared with 80% of patients with underexpressed patterns. It is concluded that autophagy is commonly upregulated in uveal melanomas, and may be associated with hypoxia and intense pigmentation. There is a strong association between extensive BECN1 overexpression and early metastases/poor prognosis, and between underexpression of this protein and late metastases/better prognosis.
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http://dx.doi.org/10.1038/modpathol.2011.63DOI Listing
August 2011

Corneal melting after collagen cross-linking for keratoconus: a case report.

J Med Case Rep 2011 Apr 16;5:152. Epub 2011 Apr 16.

Department of Ophthalmology, Democritus University of Thrace, Alexandroupolis, Greece.

Introduction: Corneal collagen cross-linking is a rather new technique that uses riboflavin and ultraviolet A light for collagen fiber stabilization in keratoconus corneas. Other than reversible side effects, the preliminary results of corneal collagen cross-linking studies suggest that it is a rather safe technique. In this report, we demonstrate a case of corneal melting after corneal collagen cross-linking for keratoconus corneas associated with an acute inflammatory response.

Case Presentation: A 23-year-old Caucasian man with keratoconus cornea stage 1 to 2 underwent uneventful corneal collagen cross-linking treatment according to the Dresden protocol. The next day the patient had intense photophobia, watering and redness of the eye, and his visual acuity was limited to counting fingers. Slit lamp biomicroscopy revealed severe corneal haze accompanied by non-specific endothelial precipitates following an acute inflammatory response. Mild inflammation could be detected in the anterior chamber. Moreover, the re-epithelialization process could barely be detected. His corneal state gradually deteriorated, resulting in descemetocele and finally perforation.

Conclusion: In this report, we present a case of a patient with corneal melting after standard corneal collagen cross-linking treatment for keratoconus corneas following an acute inflammatory response. Despite modifying postoperative treatment, elaboration of all apparent associated causes by the treating physicians and undergoing extensive laboratory testing, the patient developed descemetocele, which led to perforation. Our report suggests that further research is necessary regarding the safety of corneal collagen cross-linking in keratoconus corneas.
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http://dx.doi.org/10.1186/1752-1947-5-152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3094293PMC
April 2011

Ocular decompression retinopathy after deep sclerectomy with mitomycin C in an eye with exfoliation glaucoma.

Eur J Ophthalmol 2011 May-Jun;21(3):324-7

Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis, Greece.

Purpose: To present a case of ocular decompression retinopathy occurring after an uncomplicated nonpenetrating glaucoma procedure (deep sclerectomy with mitomycin C).

Methods: A 52-year-old man with medically uncontrolled exfoliation glaucoma in the left eye underwent uneventful deep sclerectomy with mitomycin C. The patient had no history or laboratory evidence of any bleeding disorder.

Results: On the first postoperative day, visual acuity fell from the preoperative level of Snellen 0.2 to hand movement and the intraocular pressure was 5 mmHg. Funduscopy revealed a small intravitreal hemorrhage and multiple, extended retinal hemorrhages in all quadrants of the fundus. After standard postoperative medication with antibiotic/steroid eyedrops, the patient's visual acuity returned to preoperative levels and the retinal hemorrhages were absorbed. Three and a half months postoperatively, the fundus was free of bleedings.

Conclusions: Although decompression retinopathy has previously been described after penetrating glaucoma surgery, the condition can also occur after uncomplicated deep sclerectomy. Despite the dramatic presentation, the prognosis remains favorable.
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http://dx.doi.org/10.5301/EJO.2010.5731DOI Listing
July 2011