Index Of Height Asymmetry Research Articles

Pentacam Indices in Photorefractive Keratectomy Surgery.

Refractive eye surgeries are one of the most non-emergent ophthalmic surgeries due to the effect on the reduction of refractive errors, increasing visual acuity, enhancing the quality of vision, and indirectly increasing the quality of life of patients. The aim of this study was to determine Pentacam indices in the patients who underwent photorefractive keratectomy (PRK) during 2014-2018, as well as to show their correlation with the type of refractive error. This descriptive cross-sectional study was performed on 2215 eyes of 1125 patients undergoing PRK surgery. The patients’ checklist, including demographic information, refractive index, keratometry, pachymetry, corneal surface zone indices, and progressive corneal thickness indices, was provided. All data were analyzed using the IBM SPSS software, version 25. The findings showed that there was a significant association between posterior corneal astigmatism (PCA) and anterior corneal astigmatism (ACA) (p=0.00). The mean Kmax front was recorded as 44.844 ± 1.58 D, which was significantly correlated with the type of refractive errors (p=0.00). According to the findings, there was a significant relationship between anterior chamber indices and refractive error types and their severity (p=0.00). There was also a significant correlation between the surface zone and keratoconus indices (i.e., index of surface variance - ISV, index of vertical asymmetry - IVA, index of height asymmetry - IHA, and minimum radius of curvature - Rmin) with refractive errors (p=0.00). The findings showed that some of the Pentacam indices could be related to the types of refractive errors in patients undergoing PRK surgery. Therefore, their evaluation is of great importance in this regard.

Heritability of Corneal Curvature and Pentacam Topometric Indices: A Population-Based Study.

To investigate familial aggregation of anterior and posterior corneal curvature, corneal astigmatism, and some corneal topometric indices using the Pentacam. Of 3,851 eligible individuals who resided in the selected areas, 2,779 met the conditions for analysis. However, analysis was limited to families whose Pentacam measures were available for at least 2 family members (father or mother and a child), resulting in 1,383 individuals in 382 families. All selected subjects underwent a set of examinations, including refraction, uncorrected and corrected visual acuity measurement, slitlamp biomicroscopy, and Pentacam imaging. Heritability estimation was used to calculate familial aggregation. The results of our study showed a fairly high corneal curvature heritability. The heritability of K2 and K1 in the anterior surface was 58.61% (95% confidence interval [CI], 54.99-62.23) and 55.82% (95% CI, 52.66-58.98), respectively. The heritability of posterior corneal curvature was slightly higher than that of the anterior corneal curvature. The heritability of K2 and K1 in the posterior surface was 63.42% (95% CI, 60.07-66.77) and 59.67% (95% CI, 55.85-63.49), respectively. Investigation of the quantitative topographic corneal indices showed that index of surface variance (ISV), central keratoconus index, and index of vertical asymmetry (IVA) had the highest levels of heritability (81.2% [95% CI, 73.64-88.76], 75.21% [95% CI, 67.19-82.28], and 66.46% [95% CI, 61.99-70.93], respectively). However, keratometric power deviation and index of height asymmetry had the lowest heritability levels (7.48% 95% CI, [4.94-10.02] and 18.31% [95% CI, 16.07-20.55], respectively). The familial aggregation and relatively high heritability of the corneal curvature and some keratoconus-related indices, such as ISV and IVA, confirm a high correlation between these phenotypes and genetic factors and warrant further investigation of the genetic mechanisms in keratoconus.

Combined Phototherapeutic Keratectomy, Intracorneal Ring Segment Implantation, and Corneal Collagen Cross-Linking in Keratoconus Management

To evaluate the efficacy, predictability, and safety of combined corneal collagen cross-linking (CXL), intracorneal ring segment (ICRS) implantation, and superficial phototherapeutic keratectomy (PTK) in patients with keratoconus. Fifty-five eyes received ICRS implantation, followed by CXL and PTK combination treatment. Patients were followed up for 6 months. Primary outcomes included Logarithm of the Minimum Angle of Resolution (LogMAR) uncorrected distance VA (UDVA) and corrected distance VA (CDVA), sphere, cylinder, mean spherical equivalent, index of surface variance, index of vertical asymmetry, keratoconus index, central keratoconus index, index of height asymmetry, and index of height decentration. Secondary outcomes were higher-order aberrations (HOAs), including HOA total, coma, spherical, secondary astigmatism, and trefoil. At 6 months, there was a statistically significant improvement in UDVA, CDVA, sphere, and cylinder compared with baseline (P < 0.001). UDVA improved in 14% of the eyes to 20/25 and 96% had at least 20/40 or better spectacle corrected vision; 30.9% of the eyes were within ±0.5 diopter (D), 45.5% of the eyes were within ±1.0 D, and 74.5% of the eyes were within ±2.0 D. For CDVA, 1 eye (2%) lost 3 lines (but gained UDVA), 11% lost 1 line, 38% showed no change, and 49% gained between 1 and 8 lines of vision. Eighty-eight United Arab Emiratespercent of the eyes had at least 1 line of UDVA visual improvement, 79% improved by ≥2 lines, and 69% improved by ≥3 lines. HOA total, coma, spherical aberration, and secondary astigmatism showed improvements of -0.87 (P < 0.001), -0.84 (P < 0.001), -0.10 (P = 0.002), and -0.15 (P = 0.035), respectively. A combined procedure of ICRS implantation, CXL, and PTK is effective, predictable, and apparently safe for patients diagnosed with moderate keratoconus.

The effect of corneal cross-linking on the anterior and posterior parameters of the cornea: A prospective repeatability study

Objective. To determine the effect of corneal cross-linking (CXL) on the anterior and posterior corneal indices in terms of their repeatability and change as measured with Pentacam. Methods. Thirty eyes of 30 patients with progressive keratoconus undergoing CXL were enrolled. At each visit (pre-CXL, 6 and 12 months after CXL), imaging were done twice, one hour apart to determine the repeatability index (RI) and intra-class correlation coefficient (ICC). For same session measurements, we computed the intra-session repeatability. We also calculated 4 measures of change by subtracting baseline from 1-year results and determined the repeatability of measures of change. Results. There was no significant difference between the intra-session RI at baseline, 6 months, and 12 months for anterior Kmax-3mm (P=0.609), anterior Kmin-3mm (P=0.548), Kmax-8mm (P=0.860), posterior Kmax-3mm (P=0.717), posterior Kmin-3mm (P=0.548), Q-value-6mm (P=0.890), central corneal thickness (P=0.751), minimum corneal thickness (P=0.787), or anterior chamber depth (P=0.760). The ICCs for these indices were higher than 0.9. For keratoconus indices, there was no significant difference between the intra-session RI at baseline and follow-ups (P>0.05), and the ICC were higher than 0.9 except for baseline and 6-month index of height asymmetry (IHA). The ICC for all 1-year measures of change were more than 0.75 except for posterior corneal indices and IHA. Conclusion. Pentacam repeatability of different indices is not affected by CXL. However, the change of indices showed high variance, which should be taken into consideration, especially in systematic reviews because inter-study differences can be due to low repeatability of the measures of change.

Evaluation of corneal symmetry after UV corneal crosslinking for keratoconus.

PurposeThe purpose of this study was to assess UV corneal crosslinking (CXL) treatment outcomes for keratoconus by evaluating the corneal regularity in patients through follow-up using the Oculus Pentacam.Patients and methodsA total of 18 eyes from CXL patients with keratoconus were studied before and after CXL treatment, and six eyes from six patients who were not treated with CXL served as controls. Treated patients had Pentacam images taken before CXL treatment and regularly 3 months post treatment up to the 12th month. Controls were imaged during their first appointment and after 12 months. Symmetry and asphericity were evaluated and correlated with both best-corrected visual acuity (BCVA) and maximum K-readings.ResultsIn the CXL-treated group, there was a significant improvement in the index of symmetrical variation (ISV) and keratoconus index (KI) at 3 months and in the index of height asymmetry (IHA) and minimum radius of curvature (Rmin) at 9 months post treatment. On the contrary, the untreated group’s indices showed some significant worsening in ISV, KI, central keratoconus index (CKI), and Rmin. A novel finding in our study was a slight positive shift of anterior asphericity in the 6 mm, 7 mm, and 8 mm 3 months after treatment, which had a correlation with BCVA (R2=0.390, p=0.053) and a strong correlation with maximum K-reading (R2=0.690, p=0.005). However, the untreated group had no significant changes after 1 year.ConclusionThe corneal asymmetrical shape is associated with the spherical aberration alteration influenced by temporal evolution of surface ablation and increased corneal haze. However, insignificant changes in symmetry attest the stabilization effect on cornea postoperatively as compared with controls.

Pregnancy-induced Changes in Corneal Biomechanics and Topography Are Thyroid Hormone Related

To identify biomechanical and topographic changes of the cornea during pregnancy and the postpartum period and its association to hormonal changes. Prospective single-center observational cohort study. Participants were 24 pregnant women (48eyes), monitored throughout pregnancy and after delivery. Biomechanical and topographic corneal properties were measured using the Ocular Response Analyzer (ORA) and a Scheimpflug imaging system (Pentacam HR) each trimester and 1month after delivery. At the same consultations blood plasma levels of estradiol (E2) and thyroid hormones (TSH, T3t, T4t) were also determined. A factorial MANCOVA was used to detect interactions between hormonal plasma levels and ocular parameters. Significant differences in corneal biomechanical and topographic parameters were found during pregnancy in relation to T3t (p= .01), T4t (p<.001), T3t/T4t (P= .001), and TSH (p=.001) plasma levels. E2 plasma levels (p= .092) and time period of measurement (p= .975) did not significantly affect corneal parameters. TSH levels significantly affected the maximal keratometry reading (p=.036), the vertical keratometry reading (p=.04), and the index of height asymmetry (p=.014). Those results persist after excluding hypothyroidism patients from the statistical analysis. Hormonal changes affecting corneal biomechanics and topography during pregnancy could be thyroid related. Dysthyroidism may directly influence corneal biomechanics and represents a clinically relevant factor that needs further investigation.

Evaluation of corneal topographic changes and surgically induced astigmatism after transconjunctival 27-gauge microincision vitrectomy surgery.

To evaluate the corneal topographic changes and postvitrectomy astigmatism after 27-gauge (g) microincision vitrectomy surgery (MIVS) by using Pentacam HR-Scheimpflug imaging system. This prospective descriptive study included 30 eyes of 30 patients who underwent 27-g MIVS. All eyes underwent a Pentacam HR examination preoperatively and on the first week, first month and third month postoperatively. The power of the corneal astigmatism, mean keratometry (K m), K 1 and K 2 values and corneal asphericity (Q value) values for the both front and back surfaces of the cornea, index of surface variance (ISV), index of vertical asymmetry (IVA), index of height asymmetry (IHA), index of height decentration (IHD) and higher-order aberrations including coma, trefoil, spherical aberration, higher-order root-mean-square and total RMS were recorded. Additionally, the mean induced astigmatism was estimated by vector analysis. No statistically significant changes were observed in the mean power of corneal astigmatism, mean keratometry, K 1 and K 2 values, corneal asphericity values, ISV, IVA, IHA, IHD and higher-order aberrations on the first week, first month and third month after the operation. The mean surgically induced astigmatism was calculated as 0.23±0.11 D on the first week, 0.19±0.10 D on the first month and 0.19±0.08 D on the third month postoperatively. Minor corneal surface and induced astigmatic changes are expected to result in rapid visual rehabilitation after pars plana vitrectomy with the 27-g MIVS system.

Effects of single-segment Intacs implantation on visual acuity and corneal topographic indices of keratoconus

PurposeTo assess the changes in visual acuity and topographic indices after implantation of single-segment Intacs. MethodsForty-two keratoconic eyes received Femtosecond-assisted single-segment Intacs. Uncorrected distance visual acuity (UDVA) and best spectacle corrected visual acuity (BSCVA), refractive error, keratometry (K1, K2, Km, and KMax.), and seven Pentacam measured topographical indices; index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration (IHD), and minimum radius of curvature (R Min) were assessed 4 months after surgery. Correlations between changes of visual acuity and topographical indices changes were evaluated. ResultsUDVA increased from 0.92 ± 0.35 to 0.49 ± 0.31 logMAR (P < 0.001), and BSCVA increased from 0.39 ± 0.15 to 0.23 ± 0.11 logMAR (P < 0.001). Subjective refraction spherical equivalent (SRSE) decreased from −3.92 ± 1.66 diopters (D) to −2.00 ± 1.51 D (P < 0.001). Mean central Keratometry decreased 2.16 ± 1.09 D from the preoperative readings (P < 0.001). All Pentacam topographical indices except CKI significantly improved (for IHA P = 0.046, for five others P < 0.001). The correlation between improvement in topographical indices and visual acuity improvements was not week. ConclusionIntacs implantation in keratoconic eyes increased visual acuity and made corneal shape less irregular. However, the improvements of visual acuity and corneal shape were not strongly correlated.

Mid-Term Results of a Single Intrastromal Corneal Ring Segment for Mild to Moderate Progressive Keratoconus.

To study the mid-term effects of implanting a single intracorneal ring segment (ICRS) for treatment of mild to moderate progressive keratoconus. This retrospective study was conducted on patients with progressive keratoconus treated with ICRS. The mean follow-up time was 15.2 ± 8.8 (range, 7-26) months before and 27.8 ± 7.5 (range, 18-35) months after surgery. Patients received no other treatment during this time. Of the cases studied, 59.1% had inferior keratoconus. Thirty eyes of 30 patients with a mean age of 27.5 ± 4.6 years were included in the study. Corrected distance visual acuity decreased by 1 line during the preoperative follow-up and improved by 2 lines after surgery (P < 0.05). Maximum keratometry (Kmax) of the anterior (2.39 ± 0.75 D) and posterior (0.33 ± 0.32 D) corneas at 3 mm and anterior Kmax at 8 mm (2.39 ± 0.95 D) decreased after treatment (all P < 0.05). The posterior Q value shifted toward a more oblate curvature (0.50 ± 0.52, P = 0.023). Decreases in anterior elevation at the thinnest point (5.22 ± 7.21 μm) and posterior corneal central elevation (8.89 ± 11.26 μm) were significant (both P < 0.05). Corneal thickness at the center (11.11 ± 12.38 μm) and thinnest point (15.89 ± 12.75 μm) increased after treatment (all P < 0.001). Other significant changes included postoperative decreases in the keratoconus index (0.12 ± 0.06), index of height decentration (0.06 ± 0.05), index of surface variance (27.32 ± 13.08), index of vertical asymmetry (0.42 ± 0.21), index of height asymmetry (8.42 ± 20.57), and an increase in the center keratoconus index (0.01 ± 0.02) (P < 0.001). This study demonstrates that ICRS implantation provides favorable mid-term outcomes in treatment of mild and moderate progressive keratoconus and can improve corneal indices compared with their preoperative states.

Visual, Topographic, and Pachymetric Effects of Pediatric Corneal Collagen Cross-linking.

To evaluate the effects of pediatric corneal collagen cross-linking (CXL) on corrected distance visual acuity (CDVA), maximum keratometry (Kmax), and other Scheimpflug imaging system parameters during 2 years of follow-up. The records of 29 eyes of 29 pediatric patients who underwent unilateral CXL treatment for progressive keratoconus were reviewed. Changes in CDVA, Kmax, anterior chamber depth, anterior chamber volume, anterior chamber angle, pupil-center pachymetry, apical pachymetry, thinnest pachymetry, corneal volume, and topographic indices (index of surface variance [ISV], index of vertical asymmetry [IVA], index of height asymmetry [IHA], keratoconus index [KI], center keratoconus index [CKI], index of height decentration [IHD], and minimum radius of curvature [Rmin]) were analyzed among baseline and 1 and 2 years after the CXL treatment. Mean CDVA and Kmax significantly improved from baseline at 1 year (-0.17 logMAR, P < .0001; -1.18 diopters [D], P = .012, respectively) and 2 years (-0.21 logMAR, P < .0001; -1.40 D, P = .001, respectively) after the CXL treatment. Anterior chamber parameters, corneal thicknesses, and corneal volume remained unchanged during the period following CXL (P > .05). Five of the seven Scheimpflug topographic indices (including ISV, KI, CKI, IHD, and Rmin) showed significant improvement after CXL between baseline and 2 years (P < .05). In pediatric patients with progressive keratoconus, CXL appears to be effective in improving CDVA, Kmax, and corneal topographic irregularity at 2 years' follow-up. However, long-term effects of CXL should be tested by further studies in pediatric keratoconus. [J Pediatr Ophthalmol Strabismus. 2017;54(2):84-89.].

Corneal tomographical changes following crosslinking

SummaryWe show the potential of Scheimpflug‐based tomographic indices for indication and postoperative monitoring of corneal collagen cross‐linking (CXL) performed in progressive keratoconus. The value of tomographic indices for validation of corneal flattening after CXL in the long term is being discussed. In addition, we will focus on keratoconus index (KI) and index of height asymmetry (IHA) provided by the Pentacam, which have been established in clinical routine for monitoring of the long‐term stabilization effect of CXL on the corneal architecture.

Clinical evaluation of oculus keratograph corneal topographer in normal population

PurposeCorneal topography is a non‐invasive medical imaging technique for mapping the surface of the cornea. Since cornea is normally responsible for more than 70% of eye refractive power, its topography is of great importance in determining the quality of vision and corneal health. It seems important to have detailed information of corneal topography in order to understand contribution the cornea makes to vision.Methods500 eyes of 500 normal subjects were investigated using the Oculus Corneal Topographer. Slit lap biomicroscopy was utilized in conjunction with standard descriptions of changes to assess pathologies of anterior segment. Anterior surface of the cornea and lid angle were evaluated using Oculus Corneal topographer.ResultsThe average corneal power in steepest and flattest meridian were 44.28 ± 1.51 and 43.44 ± 1.47, respectively. The mean of corneal astigmatism was −0.90 ± 0.55 diopters. The average value of corneal parameters were as follow: Eccentricity 0.52±0.11, Index of Surface Variation 18.73 ± 5.36, Index of Vertical Asymmetry 0.12 ± 0.05, Keratoconus Index 1.01 ± 0.02, Central Keratoconus Index 1.01 ± 0.01, Index of Height Asymmetry 6.21 ± 4.21 and Index of Height Decentration 0.01 ± 0.00. The mean of pupil diameter was 3.43 ± 0.72. Corneal asphericity was estimated in three diameters of 5, 6 and 7 mm and the average values were −0.21 ± 0.11, −0.24 ± 0.10 and −0.27 ± 0.11, respectively. The mean value of lid angle was reported as 12.29 ± 3.77 degrees.ConclusionsThis study have provided detailed and applicable description of computerized corneal topography parameters in a normal population which is useful in diagnosis and management of anterior segment disorders, such as keratoconus and corneal ectatic, preoperative assessments of refractive surgery procedures and contact lenses prescription.

Comparison of Scheimpflug imaging parameters between steep and keratoconic corneas of Caucasian eyes.

PurposeTo compare the keratometric and pachymetric parameters of healthy eyes with those affected by steep cornea and keratoconus (KC) using Scheimpflug camera.SettingBriz-L Eye Clinic, Baku, Azerbaijan.DesignA cross-sectional study.MethodsIn this study, 49 KC (Amsler–Krumeich stage 1) eyes and 36 healthy eyes were enrolled. A complete ophthalmic evaluation and a Scheimpflug camera scan were performed in every eye included in the study. Tomographic parameters such as parameters from the front and back cornea, maximum keratometry reading (Kmax), corneal volume (CV), anterior chamber volume (ChV), anterior chamber depth (ACD), anterior chamber angle (AC angle), keratometric power deviation (KPD), maximum front elevation (Max FE), and maximum back elevation (Max BE), as well as pachymetric progression indices (PPI), Ambrosio relational thickness (ART), index of surface variance (ISV), index of vertical asymmetry (IVA), center keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration (IHD), and radius minimum (RM) were collected and statistically compared between the two groups.ResultsPPI, ART, ISV, IVA, CKI, IHA, IHD, and RM parameter values were significantly different (P<0.05) between the KC and healthy eyes. There were no significant differences in K mean and Q values of the frontal corneal parameters, as well as in Kmax, AC angle, RM, back, and front astigmatism, between stage 1 keratoconic and normal Caucasian eyes with steep cornea. All other parameters such as K mean and Q values of the back corneal parameters, Max FE, Max BE, ACD, ChV, and CV showed significant differences between the groups (P<0.05 for all).ConclusionScheimpflug imaging is able to detect corneal morphological differences between stage 1 KC eyes and healthy eyes with steep cornea, in Caucasians.

Long-term follow-up results of corneal collagen cross-linking in keratoconus

Objective: To evaluate the changes in corneal parameters (keratometry, corneal thickness, topography indices) after corneal collagen cross-linking in keratoconus. Methods: The medical records of 6 patients who underwent corneal collagen cross-linking treatment for keratoconus and have been followed-up for a minimum of 24 months were recruited. Best corrected visual acuity (BCVA), maximum keratometry (Kmax), central corneal thickness (CCT) values and corneal topography indices: index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), minimum radius of curvature (Rmin), index of height asymmetry (IHA), and index of height decentralisation (IHD) were recorded. Results: The mean preoperative Kmax value was 46.67±4.15 (43.30-57.10) D and the mean Kmax value at the final postoperative visit was 45.41±2.95 (43.00-53.20) D. Mean preoperative CCT was 494.70±33.69 (438-537) µm and final postoperative mean CCT was 495.60±34.99 (433-539) µm. The deterioration in corneal topography indices stopped during the follow-up period of each case. Conclusion: Stopping the deterioration of corneal parameters in keratoconus is the desired outcome after cross-linking treatment. Our results found an improvement or at least stabilization in all topography indices in keratoconus patients. J Clin Exp Invest 2015; 6 (4): 343-350 Key words: Keratoconus, corneal collagen cross-linking, corneal topography

Comparison of corneal topographic indices of keratoconus versus normal eyes by using pentacam imaging

PurposeTo compare the corneal topographic indices of keratoconus versus normal eyes by using pentacam imaging.MethodsOne hundred and fifty patients (300 eyes) from keratoconus clinic based on inclusion criteria and 149 nominees (298 eyes) for refractive surgery with normal cornea were selected from the Noor Eye Hospital, Tehran, Iran. Pentacam scheimflug measurements were performed for both groups based on standard measurement factors. Pentacam topography indices were recorded for each case.ResultsAverage of topographic indices were evaluated and compared between two groups with T‐test. The difference between two groups was significant. Effective indices in discrimination suspect from normal were evaluated by logistic regression. Sensitivity and specificity of indices were plotted by ROC curve. In order to diagnose suspect keratoconus, index of height decentration (IHD) and index of height asymmetry (IHA) had the most sensitivity and specificity values.ConclusionsThe results of this study showed that the index of IHD and IHA were the most sensitive and specific criteria in the diagnosis and discrimination between keratoconus and normal eyes. Based on sensitivity and specificity criteria, the given cut‐points for each indices play an important role in detecting subclinical keratoconus from normal eyes.

Femtosecond-assisted intrastromal corneal single-segment ring implantation in patients with keratoconus: a 12-month follow-up.

To determine visual rehabilitation in patients with keratoconus who received femtosecond-assisted intrastromal corneal single-segment ring implantation. This prospective study was conducted on 62 eyes of 45 patients with keratoconus who received single-segment Intacs. The FS200 femtosecond laser was used for tunnel creation. Patients were examined for astigmatism, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and manifest refraction spherical equivalent (MRSE) before the operation and 1, 6, and 12 months after operation. Scheimpflug imaging including minimum keratometry reading (min-K), maximum keratometry reading (max-K), average of minimum and maximum keratometry readings (mean-K), central corneal thickness (CCT), asphericity (Q-value), index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), center keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration (IHD), and minimum sagittal curvature (Rmin) was performed before and 12 months after the operation. The mean preoperative UCVA was 20/130, which increased to 20/62 1 year after the operation (P < 0.001). The mean BCVA in the last follow-up was 20/32, which improved when compared with preoperative BCVA (20/40) (P = 0.008). One year after the operation, MRSE and cylinder decreased to 1.33 ± 1.90 diopter (D) and 0.46 ± 1.50 D, respectively (P < 0.001 for both). Min-K, max-k, and mean-k reduced to 1.67 ± 0.1.40 D, 2.08 ± 1.84 D, and 1.85 ± 1.30 D (P < 0.001 for all). Q-value decreased to 0.81 ± 1.14 (P < 0.001). In contrast, CKI had a significant increase of 0.02 (P = 0.002). Other evaluated indexes did not show any significant differences. Implantation of the single-segment ring in patients with keratoconus improved vision because of regularizing the cornea and centralization of the corneal cone.

Changes of Corneal Topography Indices After CXL in Progressive Keratoconus Assessed by Scheimpflug Camera

To evaluate the accuracy of Scheimpflug camera topography indices in detecting the therapeutic effect of corneal collagen cross-linking (CXL) on progressive keratoconus in the long term. Fifty eyes of 25 patients with keratoconus were enrolled. CXL was performed in 25 eyes with progressive keratoconus (CXL group) and 25 fellow eyes with nonprogressive keratoconus served as controls. Thinnest corneal thickness, anterior keratometry (flat, steep), and keratoconus indices were measured with Scheimpflug camera before and 12 to 25 months after CXL. Regression analysis was used to evaluate the influence of corneal thickness and follow-up time on flattening effect of CXL. At baseline, steep keratometric values were significantly higher and thinnest corneal thickness values were lower in the CXL group (P = .027, .034), parallel with increased values of keratoconus indices: index of surface variance (P = .013), index of vertical asymmetry (P = .038), keratoconus index (P = .019), center keratoconus index (P = .039), index of height asymmetry (P = .037), index of height decentration (P = .0016), and radius minimum (P = .008). After adjustment for thinnest corneal thickness and follow-up time, CXL showed significant flattening effect expressed by changes in radius minimum (P < .001), index of surface variance (P = .03), keratoconus index (P = .006), center keratoconus index (P = .03), and index of height asymmetry (P = .026). Thinnest corneal thickness had significant influence on changes of index of surface variance (P = .049), index of vertical asymmetry (P = .01), and center keratoconus index (P = .03). Follow-up time showed no significant influence in any models (P > .05). Topographic indices indicate corneal flattening after CXL in the long term. Monitoring keratoconus index and index of height asymmetry should be the preferred choice in daily clinical practice because changes in values of these indices are independent from initial corneal thickness.

Effects of Corneal Collagen Crosslinking on Corneal Topographic Indices in Patients With Keratoconus

To evaluate the effects of corneal crosslinking (CXL) on corneal topographic indices in patients with progressive keratoconus using Scheimpflug imaging system. This retrospective study comprised 59 eyes of 47 patients who underwent CXL treatment for confirmed progressive keratoconus. Changes in corrected distance visual acuity (CDVA, logMAR equivalent), maximum keratometry (K), and corneal topographic indices included index of surface variance (ISV), index of vertical asymmetry, keratoconus index, center keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration, and minimum radius of curvature (Rmin) were analyzed at 1-year follow-up. Correlations between topographic indices and visual acuity were sought. The study included 59 eyes of 47 patients with progressive keratoconus. The mean CDVA (P<0.001), maximum K (P<0.001), ISV, Rmin, and CKI (P =0.013, P < 0.001, respectively) significantly improved after CXL treatment. Moreover, we found a significant negative correlation between the change in IHA value and the improvement in CDVA (r = -0.351; P = 0.006). In patients with progressive keratoconus, cornea becomes more optically regular after CXL treatment. Changes in topographic indices might be valuable to follow-up the normalization of keratoconic cornea during the postoperative course and superior-inferior height symmetry seems to be associated with visual improvement.

Alterations of Tear Mediators in Patients with Keratoconus after Corneal Crosslinking Associate with Corneal Changes

Keratoconus (KC) is the most common primary corneal ectatic disease which has considerable importance in public health. Corneal collagen crosslinking (CXL) is a procedure to mitigate progression of KC and reduce demand for corneal transplantation. Although studies have proven the efficacy of CXL regarding corneal shape, none have investigated the effects of CXL on tear biomarkers which are useful tools to understand molecular mechanisms behind CXL. Our purpose was to determine the effect of CXL on tear mediators in patients with KC and analyze associations with corneal changes. Tear samples were collected pre-CXL from 26 eyes of 23 patients and during a 12-month follow-up. The mediators’ concentration was measured by Cytometric Bead Array technology. Corneal topography parameters measured by Scheimpflug Camera included: Thinnest-corneal-thickness (ThCT), keratometry values (K1, K2), Radii-Minimum (Rmin), Keratoconus-Index (KI), Center-KI (CKI), Index-of-Height Asymmetry (IHA) and Index-of-Surface Variance (ISV). At baseline, KI was correlated negatively with chemokine (C-C motif) ligand 5 (CCL5) (p=0.015) and matrix metalloproteinase (MMP)-13 (p=0.007). At day 4, interleukin (IL)-6 and IL-8 increased, while IL-13, IL-17A, interferon (IFN)-γ, CCL5, MMP-13, epidermal growth factor (EGF), nerve growth factor (NGF) and plasminogen activator inhibitor (PAI-1) decreased significantly compared to pre-CXL concentrations (p≤0.02). At 6 months tissue plasminogen activator (t-PA) increased (p=0.02), while at 12 months Rmin increased (p≤0.004), and IL-6 and CXCL8 (p=0.005 and p=0.047) as well as K1, ISV and KI decreased. After 6 months CKI and ISV showed significant associations with IL-17A; CKI with IL-13 and ThCT with IL-13 (p≤0.02), while at 12 months there were reverse associations between ThCT and IL-6, IL-13, INFγ, CCL5 and PAI-1 (p≤0.02). Alterations of mediators in tear fluid after CXL associate with topographic changes highlight the fact that many mediators are involved in the complex mechanisms after CXL. Further studies on biomarkers to investigate the efficacy of CXL are needed.

Interaction Between Topographic/Tomographic Parameters and Dry Eye Disease in Keratoconus Patients

Purpose: To determine the interaction between corneal topographic and tomographic parameters and dry eye syndrome (DES) in keratoconus (KC) patients.Methods: Seventy-seven eyes of 49 patients with KC (age 34.4 ± 11.6 years) were enrolled in this study. In these 77 eyes we recorded surface regularity index (SRI), surface asymmetry index (SAI) and Klyce/Maeda KC index (KCI) using the Topographic Modeling System (TMS-5, Tomey, Tennenlohe, Germany), Index of Surface Variance (ISV), Index of Vertical Asymmetry (IVA), KC Index (KI), Center KC Index (CKI), Index of Height Asymmetry (IHA) and Index of Height Decentration (IHD) using Pentacam (Pentacam HR, Oculus, Germany). Patients were subdivided into mild (grade 1–2) and severe stage (grade 3–4) KC groups according to Pentacam grading.To analyse tear film parameters we assessed in 77 KC eyes McMonnies questionnaire, Schirmer test and break-up time and in 26 eyes (10 eyes with mild KC, 16 eyes with severe KC) high-speed videokeratoscopy (during interblinking interval) using a novel commercially not available system (Tear Inspect). With Tear Inspect the analysed tear film parameters were (1) time of first irregularities of Placido rings and (2) time of eyelid closure. Patients were also subdivided into McMonnies questionnaire positive and negative groups.Results: We did not find significant difference between patients with mild and severe KC in any of the examined tear film parameters (p > 0.66). There was no significant difference in SRI, SAI, KCI, ISV, IVA, KI, CKI, IHA and IHD in McMonnies test positive and negative KC patients (p > 0.07). There was no correlation between SRI, SAI, KCI, ISV, IVA, KI, CKI, IHA and IHD and any of the examined tear film parameters (without high-speed videokeratoscopy) neither in 77 KC patients nor in mild or severe KC eyes (r < 0.3).Conclusions: There is no interaction between DES and topographic/tomographic changes in KC-patients.