Athanassios Giarmoukakis

Biomechanical diagnosis of keratoconus: evaluation of the keratoconus match index and the keratoconus match probability

Purpose:   To evaluate the diagnostic capacity of the Ocular Response Analyser’s keratoconus match index (KMI) and keratoconus match probability (KMP) classification in a sample of keratoconus (KC) patients.

Corneal biomechanical properties and anterior segment parameters in forme fruste keratoconus

Purpose. To evaluate the sensitivity and specificity of corneal biomechanical metrics, anterior segment data, and a combination model in differentiating forme fruste keratoconus (FFK) from normal corneas. Methods. A total of 50 FFK eyes were identified by calculation of the KISA index and recruited FFK group. Results were compared with 50 normal eyes (NG group) randomly selected from 50 patients. The following parameters were evaluated for their diagnostic capacity by evaluation of their receiver operating characteristic curves (ROC): corneal hysteresis (CH), corneal resistance factor (CRF), corneal astigmatism (Cyl), anterior chamber depth (ACD), corneal volume (CV) at 3 mm (CV3) and at 5 mm (CV5), maximum posterior elevation value (PEL), central corneal thickness (CCT), thinnest corneal thickness (TCT) and its coordinates (TCTx, TCTy), the ratio TCT/CCT, pachymetric progression indexes (PPImin, PPIavg, and PPImax), and Ambrósios relational thickness (ARTmin, ARTavg, and ARTmax). Logistic regression was attempted for identification of a combined diagnostic model. Results. Significant differences were detected in all studied parameters except the Cyl, ACD, TCTx, and CV. Among individual parameters, the highest predictive accuracy was for ARTavg (area under the curve [AUC] 95.4%, sensitivity 90%, specificity 88.9%) and TCT (AUC 95.3%, sensitivity 90.9%, specificity 89%). Sufficient predictive accuracy (AUC 99.4%, sensitivity 98.8%, specificity 94.6%) was identified in a diagnostic model that combined the CRF, ARTavg, and PEL parameters. Conclusions. None of the individual parameters provide sufficient diagnostic capacity in FFK. However, diagnostic models that combine biomechanical and tomographic data seem to provide high accuracy in differentiating FFK from normal corneas.

Mini-monovision versus multifocal intraocular lens implantation.

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.

Diagnostic capacity of the keratoconus match index and keratoconus match probability in subclinical keratoconus

Purpose To evaluate the diagnostic capacity of the Ocular Response Analyzer’s keratoconus match index (KMI) and keratoconus match probability (KMP) classification in keratoconus‐suspect eyes. Setting Department of Ophthalmology, University Clinics Saarland, Homburg, Germany. Design Comparative case series. Methods The KMI and KMP parameters in keratoconus‐suspect eyes and normal eyes (control group) were compared. The quantitative keratoconus percentage index was calculated for all suspect eyes. According to the thinnest corneal thickness (TCT), keratoconus‐suspect eyes were divided into 2 subgroups: subgroup 1 (TCT <520 &mgr;m) and subgroup 2 (TCT >520 &mgr;m). The KMI’s overall predictive accuracy was assessed using receiver operating characteristic (ROC) curves. The relationship between KMI and a series of Scheimpflug‐derived keratoconus‐related indices was evaluated using Spearman analysis. Results The mean KMI was 0.41 ± 0.29 (SD) in the keratoconus‐suspect group (50 eyes) and 0.94 ± 0.29 in the control group (50 eyes) (P<.001). Nonsignificant KMI differences were detected between the keratoconus‐suspect subgroups (subgroup 1, 27 eyes; subgroup 2, 23 eyes) (P=.059). Nonsignificant correlations were found between Scheimpflug indices and the KMI. The KMP identified 27.65% of control eyes as keratoconus suspect and 10.71%, 28.57%, and 3.57% of keratoconus‐suspect eyes as being normal, having mild keratoconus, or having moderate keratoconus, respectively. The ROC analysis for the KMI indicated a predictive accuracy of 94% (cutoff point 0.72). Conclusions The KMI seems to be a valuable index in the early diagnosis of keratoconus‐suspect eyes. The KMP identified a significant percentage of topographically defined keratoconus‐suspect eyes as normal or keratoconic. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

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

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. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Evaluation of the efficacy of the Allegretto Wave and the Wavefront‐optimized ablation profile in non‐anterior astigmatisms

Purpose:  To assess the efficacy of the Allegretto Wave and the wavefront‐optimized ablation profile (WFO) in non‐anterior astigmatism correction, in both LASIK and photorefractive keratectomy (PRK) treatments.

Contribution of Reference Bodies in Diagnosis of Keratoconus

Purpose To evaluate the contribution of reference bodies for elevation maps in diagnosis of keratoconus (KC) and forme fruste keratoconus (FFK). Methods Study groups included (1) 80 eyes with KC, (2) 55 eyes with FFK, and (3) 95 eyes as control eyes. The maximum elevation value at the central 5 mm of the posterior cornea (MEL) and the elevation value at thinnest corneal point (TEL) were evaluated for their diagnostic capacity using receiver operating characteristic curves under the following reference bodies: sphere, ellipsoid, toric ellipsoid, and torus, with autodiameter and fixed 8-mm-diameter settings. Moreover, characteristic parameters for each reference body and the root mean square (RMS) were evaluated for their diagnostic capacity. Results Significant differences were detected in TEL, MEL, and RMS parameters among groups, for almost all reference bodies. The highest predictive accuracy (KC group, >99.97%; FFK group, >90.9%) was estimated for the TEL and MEL parameters using the toric ellipsoid (8 mm) reference body with a fixed eccentricity of 0.4. Moreover, the RMS parameter demonstrated sufficient diagnostic capacity (KC group, 99.95%; FFK group, 85.1%). The cutoff points for the TEL parameter were found to be 7 and 3 &mgr;m in the KC group and the FFK group, respectively; for the MEL parameter, they were 11 and 6 &mgr;m, respectively; and for the RMS parameter, they were 6.87 and 7.19 &mgr;m, respectively. Conclusions The posterior corneal elevation values and the RMS parameter can effectively discriminate KC from normal corneas, although measured values and cutoff points depend on the selection of reference body. Moreover, the use of a toric ellipsoid reference body, with a fixed eccentricity of 0.4, seems to be an effective tool even in diagnosis of FFK.

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

IntroductionInfectious 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 presentationA 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.ConclusionCorneal collagen cross-linking seems to be a safe and effective therapeutic alternative in resistant cases of infectious keratitis following penetrating keratoplasty.

Diagnostic capacity of biomechanical indices from a dynamic bidirectional applanation device in pellucid marginal degeneration.

Purpose To evaluate the diagnostic capacity of the keratoconus match index (KMI) and keratoconus match probability (KMP) classification from a dynamic bidirectional applanation device (Ocular Response Analyzer) in eyes with pellucid marginal degeneration (PMD). Setting Department of Ophthalmology, University Clinics Saarland, Homburg, Germany. Design Cross‐sectional study. Methods Pellucid marginal degeneration eligibility was confirmed by inferior peripheral thinning, corneal protrusion, and irregular astigmatism. The KMI and KMP parameters in PMD eyes (study group) were compared with those in normal eyes (control group). The KMI’s overall predictive accuracy was assessed operating characteristic (ROC) curves. The relationship between KMI and corneal hysteresis (CH), the corneal resistance factor (CRF), and a series of Scheimpflug camera indices was evaluated with Spearman analysis (r). Results The mean KMI in the study group (40 eyes) and control group (40 eyes) was 0.34 ± 0.43 (SD) and 0.95 ± 0.30, respectively (P<.001). The KMI correlated significantly with the CH, CRF, and most Scheimpflug camera indices. Regression analysis indicated that the index of height decentration (r = −0.877, P<.001) was the primary determinant of the KMI. Moreover, the KMP index identified 50.0%, 29.16%, and 20.83% of PMD eyes as ectatic, suspect for ectasia, and normal, respectively. The ROC curve analysis of the KMI parameter indicated a predictive accuracy of 94.8% (cutoff point 0.626; sensitivity 85.71%; specificity 90.1%). Conclusions The KMI seems to be a promising diagnostic index for PMD. In contrast, the KMP index identified a significant percentage of topographically defined PMD eyes as normal, limiting its diagnostic value in PMD. Financial Disclosures No author has a financial or proprietary interest in any material or method mentioned.

Liquefaction versus Torsional IP: A Comparative Study on Endothelial Cells, Corneal Edema and Corneal Sensitivity

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.