Keratoconus Index Research Articles

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.

Brillouin Spectroscopy of Normal and Keratoconus Corneas

To investigate the age dependence of Brillouin spectroscopy of the cornea and to compare normal and keratoconus corneas. Retrospective case-control study. Study Population: Healthy patients and patients suffering from keratoconus seen at the Institut für Refraktive und Ophthalmo-Chirurgie (IROC) between December 2016 and March 2017. Brillouin frequency shifts of patients of 2 different groups were examined with Brillouin spectroscopy perpendicular to the corneal surface. Group 1 consisted of 47 healthy eyes, whereas Group 2 included 36 eyes with keratoconus of unclear progression. Besides Brillouin examinations, corneal tomographies were acquired so that correlations and comparisons between geometric parameters and Brillouin frequency shifts could be evaluated. Corneal Brillouin frequency shifts averaged over full corneal thickness. A significant correlation between age and central Brillouin frequency shift was identified (P= .011) with an increase in Brillouin frequency shift of 4 MHz per decade in normal corneas. Keratoconus corneas have a significantly reduced Brillouin frequency shift at the thinnest point compared to normal corneas (5.7072 ± 0.0214 vs 5.7236 ± 0.0146 GHz, P < .001). The Brillouin frequency shift at the point of maximum posterior elevation showed best correlation with geometry-derived keratoconus indices. The receiver operating characteristic curve analysis of Brillouin frequency shift showed substantially worse sensitivity and specificity compared to Kmax and thinnest pachymetry for keratoconus detection. Noninvasive Brillouin spectroscopy adds clinical information about the biomechanical state of the cornea perpendicular to the surface. An age-dependent stiffening of the cornea has been found and keratoconus corneas are statistically significantly different from normal corneas, but for precise differentiating of keratoconus stages (including normal corneas) the method is currently neither specific nor sensitive enough. Further development including standardized mapping and establishment of new indices may increase the potential of Brillouin spectroscopy substantially.

Comparative Functional Outcomes After Corneal Crosslinking Using Standard, Accelerated, and Accelerated With Higher Total Fluence Protocols.

To compare the relative 12-month corneal crosslinking (CXL) functional outcomes using standard protocol and accelerated protocols in patients with progressive keratoconus. CXL was performed using 3 epithelium-off protocols: standard [3 mW/cm for 30 minutes, 5.4 J/cm (S3/30-CXL)], accelerated with equivalent total irradiance [9 mW/cm for 10 minutes, 5.4 J/cm (A9/10-CXL)], and accelerated with increased total irradiance [30 mW/cm for 4 minutes, 7.2 J/cm (A30/4-CXL)]. Efficacy measurements were evaluated 12 months after treatment with Scheimpflug imaging (Pentacam HR) and included change in maximum keratometry (K Max), corrected distance visual acuity (CDVA), other keratometric variables, pachymetry, keratoconus indices, astigmatism, asphericity, manifest refraction, and higher order aberrations. Ninety-three eyes (67 patients) were evaluated: 35 eyes (26 patients) with S3/30-CXL, 29 eyes (19 patients) with A9/10-CXL, and 29 eyes (22 patients) with A30/4-CXL. Mean [INCREMENT]K Max was -1.53 ± 2.1 diopter (D) for S3/30-CXL, -0.71 ± 1.3 D for A9/10-CXL, and -0.70 ± 2.3 D for A30/4-CXL (P = 0.37). Mean [INCREMENT]CDVA(logMAR) was -0.18 ± 0.2 for S3/30-CXL, -0.13 ± 0.2 for A9/10-CXL, and -0.18 ± 0.2 for A30/4-CXL (P = 0.79). [INCREMENT]K Mean (r = -0.29 to -0.46), anterior asphericity (r = -0.34 to -0.40), and central keratoconus index (r = -0.18 to -0.38) best correlated with [INCREMENT]CDVA. S3/30-CXL had greater changes in index of surface variance, index of vertical asymmetry, keratoconus index, and regularization index compared to A9/10-CXL and A30/4-CXL. There were no other differences between protocols. All 3 protocols showed improvements in K Max, CDVA, and other variables, with similar functional outcomes for each despite greater change in keratoconus indices after S3/30-CXL. Correlations between change in measured variables and CDVA were poor overall; however, K Mean, central keratoconus index, and anterior asphericity were better correlated with CDVA than K Max.

Keratoconus severity identification using unsupervised machine learning.

We developed an unsupervised machine learning algorithm and applied it to big corneal parameters to identify and monitor keratoconus stages. A big dataset of corneal swept source optical coherence tomography (OCT) images of 12,242 eyes acquired from SS-1000 CASIA OCT Imaging Systems in multiple centers across Japan was assembled. A total of 3,156 eyes with valid Ectasia Status Index (ESI) between zero and 100% were selected for the downstream analysis. Four hundred and twenty corneal topography, elevation, and pachymetry parameters (excluding ESI Keratoconus indices) were selected. The algorithm included three major steps. 1) Principal component analysis (PCA) was used to linearly reduce the dimensionality of the input data from 420 to eight significant principal components. 2) Manifold learning was used to further reducing the selected principal components nonlinearly to two eigen-parameters. 3) Finally, a density-based clustering was applied to the eigen-parameters to identify eyes with keratoconus. Visualization of clusters in 2-D space was used to validate the quality of learning subjectively and ESI was used to assess the accuracy of the identified clusters objectively. The proposed method identified four clusters; I: a cluster composed of mostly normal eyes (224 eyes with ESI equal to zero, 23 eyes with ESI between five and 29, and nine eyes with ESI greater than 29), II: a cluster composed of mostly healthy eyes and eyes with forme fruste keratoconus (1772 eyes with ESI equal to zero, 698 eyes with ESI between five and 29, and 117 eyes with ESI greater than 29), III: a cluster composed of mostly eyes with mild keratoconus stage (184 eyes with ESI greater than 29, 74 eyes with ESI between five and 29, and 6 eyes with ESI equal to zero), and IV: a cluster composed of eyes with mostly advanced keratoconus stage (80 eyes had ESI greater than 29 and 1 eye had ESI between five and 29). We found that keratoconus status and severity can be well identified using unsupervised machine learning algorithms along with linear and non-linear corneal data transformation. The proposed method can better identify and visualize the keratoconus stages.

Pentacam topographic changes after Epithelium-off collagen cross-linking versus Epithelium-on collagen cross-linking in patients with keratoconus

Keratoconus is a bilateral non-inflammatory disease .One of its characteristics is reduction of biomechanical strength of cornea and stromal thinning , which gradually decreases corneal thickness and induces irregular astigmatism , myopia , corneal scaring, andreduction of visual acuity.(1)For early stages of keratoconus , one would use spectacles and contact lenses though the progression of the disease can lead to irregular astigmatism or corneal scaring, leaving no other option but corneal transplantation in about 20% of patients.(2)Corneal transplantation is an expensive procedure with many complications such as high astigmatism and graft rejection; hence, seeking for a way to halt this progressive disease seems to be of crucial importance.(3) For more than a decade, corneal cross-linking (CXL) has been considered as the only method for improvingcorneal biomechanical power.(4)Corneal collagen cross-linking (CXL) is a low-invasive treatment aimed to improve biomechanical stability in eyes with keratectasia.(5) The “standard CXL protocol” described by Wollensak and colleagues includes removal of the corneal epithelium in a diameter of 9 mm , followed by saturation of the corneal stroma using 0.1% isotonic riboflavin solution in 20% dextran.(6)This procedure is proved to be effective in increasing corneal stiffness , stabilization of keratoconus , and in some cases in improving the refractive and topographic features.Even so, the epithelial removal may lead to serious complications that include infection(7),stromal haze (8), and corneal melting (9)in addition to severe pain and decrease in vision occurring during the first days after the treatment.To avoid such complications, Boxer Wachler et al. suggested a modification of the technique by keeping the epithelium intact (epithelium-on or transepithelial CXL) (10).In this study, we sought to compare keratoconus indices before and after crosslinking either epi-off or epi-on CXL by Pentacam criteria.

Evaluation of Scheimpflug Tomography Parameters in Subclinical Keratoconus, Clinical Keratoconus and Normal Caucasian Eyes.

Objectives:To evaluate tomographic and topographic parameters in subclinical and clinical keratoconus eyes by comparing them with normal eyes in a young Caucasian population.Materials and Methods:This cross-sectional study included 88 normal eyes (control group), bilateral data from the preclinical stage of 24 progressive keratoconus eyes (bilateral subclinical keratoconus group), 40 fellow eyes of patients with unilateral keratoconus (fellow eyes group) and 97 eyes with mild keratoconus (clinical keratoconus group). Topographic and tomographic data, data from enhanced elevation maps and keratoconus indices were measured in all study eyes using Scheimpflug tomography. Receiver operating characteristic (ROC) curve analysis was used to assess individual parameters to discriminate eyes of patients with subclinical and clinical keratoconus from control eyes. The sensitivity and specificity of the main effective parameters were evaluated and optimal cut-off points were identified to differentiate subclinical keratoconus and keratoconus from normal corneas.Results:Comparison of all subclinical and clinical keratoconus eyes from the normal group revealed significant differences in most diagnostic parameters. The ROC curve analysis showed high overall predictive accuracy of several Pentacam parameters (overall D value, anterior and posterior elevations and difference elevations, pachymetry progression index, index of surface variance, index of height decentration and keratoconus index) in discriminating ectatic corneas from normal ones. These outcomes were proportionally less pronounced in all subclinical keratoconus eyes than in the clinical keratoconus eyes. Pachymetric readings were progressively lower in the bilateral subclinical keratoconus eyes and sensitivity and specificity of the analyzed tomographic and topographic parameters were higher than the fellow eyes group when differentiating subclinical keratoconus from healthy corneas.Conclusion:Scheimpflug tomography parameters such as D value, elevation parameters, progression index and several surface indices can effectively differentiate keratoconus from normal corneas in a Caucasian population. Nevertheless, a combination of different data is required to distinguish subclinical keratoconus.

Comparison of Corneal Collagen Cross-Linking Protocols Measured With Scheimpflug Tomography.

To evaluate the effectiveness of corneal collagen cross-linking with Dresden and accelerated protocols to treat keratoconus by Scheimpflug tomography. Fifty-eight eyes with manifest keratoconus were measured preoperatively at least twice with the Pentacam. The difference of relevant variables for keratoconus progression (eg, D value, thinnest pachymetry, Kmax) was established. After evident progression, patients underwent corneal cross-linking (29 eyes with the Dresden protocol and 29 eyes with the accelerated protocol). Postoperatively, variables used for defining manifest progression were compared again by measuring the difference between 2 measurements. Preoperatively, the mean D value was 9.6 ± 4.8 for the Dresden cohort and 8.3 ± 5.1 for the accelerated cohort. There was no significant difference between both cohorts in terms of the mean preoperative difference in the D value (0.59 ± 1.7 for the Dresden cohort vs. 0.4 ± 1.49, P = 1). Postoperatively, however, a significant difference (P < 0.01 for the accelerated corhort) was found (Dresden: -0.47 ± 0.88 vs. accelerated: 0.04 ± 0.67). Regression analysis showed that keratoconus progression was significant in both study groups preoperatively (with a significant reduction of corneal thickness and increase in the D value). Postoperative data show an improvement in all observed keratoconus indices in both study groups and stagnation in progression for the accelerated cohort, P = 0.774, for the D value and a regression in manifestation for the Dresden cohort (decrease in the D value, P < 0.01). Before operative intervention, Scheimpflug imaging showed signs of a progressive disease in all eyes. Both conventional Dresden protocol and accelerated pulsed corneal collagen cross-linking techniques effectively stopped this progression.

Early Tomographic Changes in the Eyes of Patients With Keratoconus.

To identify tomographic variables best suited for detecting keratoconus before manifestation of ectatic changes and showing disease progression in the early stage. Twenty-seven patients with diagnosed unilateral keratoconus were followed up for their fellow eye, which had not yet shown any ectatic changes, to determine initial change indicators toward keratoconus disease. Variables were compared to 50 normal eyes without any known disease. A following receiver operating characteristic (ROC) analysis was performed to reveal the variables best used to discriminate healthy eyes from early ectatic eyes. The calculated mean difference of the cylinder for total corneal refractive power was only 0.07 ± 0.32 diopters (D) (anterior astigmatism = 0.12 ± 0.28 D and posterior astigmatism = 0.02 ± 0.10 D). ROC revealed the index of height decentration with an area under the curve of 0.788 ± 0.054 as the most suitable to differentiate between eyes of healthy patients and the non-ectatic eye of patients with asymmetrical keratoconus, followed by the index of vertical asymmetry of 0.772 ± 0.057 and a keratoconus index of 0.743 ± 0.062. However, with progression of the eyes into early ectactic stages, the ROC showed the highest area under the curve for D-index (0.876 ± 0.039), followed by index of height decentration (0.855 ± 0.046) and index of vertical asymmetry (0.842 ± 0.046). Early stages of keratoconus are hard to diagnose and best results can be achieved by using index of height decentration and index of vertical asymmetry. As the disease progresses, D-index is better suited to diagnose an ectasia. Astigmatism, keratometry, and pachymetry barely change in the early stages, so these values are not as fitting as corneal elevation parameters for early diagnosis. [J Refract Surg. 2018;34(4):254-259.].

The effects of chalazion surgery on intraocular pressure and corneal topography

To evaluate the effects of chalazion surgery on intraocular pressure (IOP) and the biomechanical, topographic, and topometric properties of the cornea. A total of 29 patients with upper eyelid chalazion were included in this study. All patients underwent preoperative and postoperative detailed ophthalmological examinations including scale of chalazion size; IOP (IOPcc and IOPg), corneal hysteresis, and corneal resistance factor measurements using ocular response analyser (ORA; Reichert Instruments, Depew, NY, USA); topographic and topometric properties of the cornea using Pentacam HR (Oculus GmbH, Wetzlar, HE, Germany). Preoperative and postoperative measurements were compared. The mean age of the patients was 29.07 ± 13.74years (18-54years). The mean IOPcc was 15.82 ± 4.20mmHg preoperatively and 14.72 ± 3.96mmHg postoperatively, and the mean IOPg was 15.21 ± 3.91mmHg preoperatively and 14.21 ± 4.02mmHg postoperatively (p = 0.020, p = 0.007, respectively). The mean central keratoconus index (CKI) was 1.006 ± 0.01 preoperatively and 1.002 ± 0.01 postoperatively (p = 0.035). Other biomechanical, keratometric, topographic, and topometric parameters were similar before and after the surgery (all p > 0.05). To the best of our knowledge, this is the first report to suggest that IOP and CKI are decreased after the removal of upper eyelid chalazion.

Visual rehabilitation in moderate keratoconus: combined corneal wavefront-guided transepithelial photorefractive keratectomy and high-fluence accelerated corneal collagen cross-linking after intracorneal ring segment implantation

BackgroundTo investigate the effects of combined corneal wavefront-guided transepithelial photorefractive keratectomy (tPRK) and accelerated corneal collagen cross-linking (CXL) after intracorneal ring segment (ICRS) implantation in patients with moderate keratoconus.MethodsMedical records of 23 eyes of 23 patients undergoing combined tPRK and CXL after ICRS implantation were retrospectively analyzed. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), corneal indices based on Scheimpflug tomography, higher-order aberrations (HOAs), and corneal biomechanical properties were evaluated before and after ICRS implantation, and at 1, 3, and 6 months after combined tPRK and CXL.ResultsThere were significant improvements in final logMAR UDVA and logMAR CDVA, and reductions in sphere, MRSE, and all corneal indices from baseline. Significant improvements in logMAR UDVA and reductions in sphere, MRSE, maximal keratometry, keratometry at the apex, mean keratometry, and keratoconus index were noted after ICRS implantation. After tPRK and CXL, significant improvements in logMAR UDVA and logMAR CDVA, and reductions in cylinder and all corneal indices were observed. There were significant improvements in final root mean square HOAs and coma aberrations from baseline, but no changes from baseline after ICRS implantation. Significant reductions in final radius and deformation amplitude from baseline were noted.ConclusionsCombined tPRK and accelerated CXL after ICRS implantation in moderate keratoconus appears to be a safe and effective treatment, providing an improvement in visual acuity, corneal indices, and HOAs.Trial registrationretrospectively registered (identification no. NCT03355430). Date registered: 28/11/2017.

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.

Topo‐ and tomographical keratoconus indices in case of progression

SummaryEspecially in an early stage topography and tomography are perfect tools for diagnosis of keratoconus. Corneal crosslinking requires a documented progression of keratoconus. In this talk we would like to address the Instrument‐based documentation of keratoconus progression for qualifying a Patient for corneal crosslinking in case of keratoconus. Special focus is given to the TMS‐5, the CASIA2 and the Pentacam.

Keratoconus Screening Indices and Their Diagnostic Ability to Distinguish Normal From Ectatic Corneas

To compare the diagnostic ability of 3 Scheimpflug devices in differentiating normal from ectatic corneas. Comparison of diagnostic instrument accuracy. This study included 42 normal, 37 subclinical keratoconic, and 51 keratoconic eyes seen in a tertiary eye care institute. Keratoconus screening indices were evaluated using the Pentacam (Oculus, Wetzlar, Germany), Galilei (Ziemer, Biel, Switzerland), and Sirius (Costruzione Strumenti Oftalmici, Florence, Italy). Sensitivity, specificity, and area under receiver operating characteristic curve (AUC) were calculated. Highest sensitivity (100%) to diagnose keratoconus was seen for 6 parameters on Pentacam and 1 on Galilei. None of the indices in Sirius reached 100% sensitivity. For subclinical keratoconus, the highest sensitivity (100%) was seen for 2 parameters on Pentacam but for none of them on Galilei and Sirius. All parameters were strong enough to differentiate keratoconus (AUC> 0.9). On comparing the best parameters of all 3 machines, the AUC of the Belin/Ambrosio enhanced ectasia total derivation (BAD-D) and the inferior-superior value (ISV) of Pentacam were statistically similar to that of the keratoconus prediction index (KPI) and keratoconus probability (Kprob) of Galilei (P= .27) and 4.5mm root mean square per unit area (RMS/A) back of Sirius (P= .55). When differentiating subclinical from normal corneas, BAD-D was similar to the surface regularity index (SRI) of Galilei (P= .78) but was significantly greater than the 8mm RMS/A back of Sirius (P= .002). Keratoconus indices measured by all 3 machines can effectively differentiate keratoconus from normal corneas. However, new cutoff values might be needed to differentiate subclinical from normal corneas.

Incidence and Indices of Keratoconus in Patients presenting for LASIK in Egypt

ABSTRACT Background Keratoconus (KC) is a progressive, non-inflammatory bilateral but (usually asymmetrical) ecstatic corneal disease, characterized by paraxial stromal thinning and weakening that leads to corneal surface distortion. The reported incidence and prevalence of KC varies widely depending upon the geographic location, diagnostic criteria used and the cohort of patients selected. Aim To estimate the incidence and indices of KC in patients seeking refractive procedures in Beni Sueif governorate at a span period of one year from March 2013 to March 2014. To describe and analyze the characteristics of the KC population under study. Materials and methods This study as designed as a prospective surveillance study. All clinical records in the computerized database from pentacam with the clinical diagnosis of KC and / or suspected were included and statistically analyzed. Results Data from 2116 cases with the average 28.8 ± 6.5 years old were analyzed over the span of 1 year starting from March 2013 to March 2014. Based on topographic images of the pentacam 36 eyes were diagnosed as KC. The incidence of KC was 1.7% ( 95% confidence interval, 0.55-1.45). In keratoconic patients, the mean age was 28.1 years, the mean K1 and K2 were 45.18±3.44 D and 49.49 ± 4.28 D respectively. The mean minimal pachymetry value was 463± 6.51um, the mean index of surface variance (ISV) was 61± 32, the mean index of vertical asymmetry (IVA) was 0.63±0.38, the mean keratoconus indices (KI) was 1.08±0.14. Conclusion This study provides the first population–based estimate of the incidence of keratoconus in Beni suef governorate in the upper Egypt. According to this study incidence rate of KC is comparable to the rate among the Caucasian people in middle Asia e.g. Iran while incidence rate is much higher among Malaysia and Kingdom of Saudi Arabia citizens. How to cite this article El Sayed MOAK, Ali NH. Incidence and Indices of Keratoconus in Patients presenting for LASIK in Egypt. Int J Kerat Ect Cor Dis 2017;6(1):17-22.

Iontophoresis-assisted corneal crosslinking using 0.1% riboflavin for progressive keratoconus.

To report the clinical results of iontophoresis-assisted epithelium-on corneal crosslinking (I-CXL) using 0.1% riboflavin in distilled water for progressive keratoconus. In this prospective clinical study, we examined 94 eyes of 75 patients with progressive keratoconus who were treated with I-CXL using 0.1% riboflavin in distilled water. Best correct visual acuity (BCVA), Scheimpflug tomography, corneal topography, anterior segment optical coherence tomography, intraocular pressure, and endothelial cell density were evaluated at baseline and 1, 3, 6, 12, and 24mo after I-CXL. After 24mo I-CXL, compared to the level at baseline, BCVA significantly improved 0.14±0.07 (P=0.010); mean keratometry signifi-cantly decreased 0.72±1.97 (P=0.021); maximum keratometry significantly reduced 2.30±5.01 (P=0.014); central keratoconus index significantly reduced 0.04±0.08 (P=0.007). The demarcation line was visible in 83.1% of eyes at 1mo after treatment, with a depth of 298.95±51.97 µm, and gradually indistinguishable. One eye had repeat treatment. Intraocular pressure and endothelial cell density did not change significantly. I-CXL using 0.1% riboflavin halts keratoconus progression within 24mo, resulting in a significant improvement in visual and topographic parameters. Moreover, the depth of the demarcation line is similar to that previously reported in standard epithelium-off CXL procedures.

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.

Complementary Keratoconus Indices Based on Topographical Interpretation of Biomechanical Waveform Parameters: A Supplement to Established Keratoconus Indices.

Purpose. To build new models with the Ocular Response Analyzer (ORA) waveform parameters to create new indices analogous to established topographic keratoconus indices. Method. Biomechanical, tomographic, and topographic measurements of 505 eyes from the Homburger Keratoconus Centre were included. Thirty-seven waveform parameters (WF) were derived from the biomechanical measurement with the ORA. Area under curve (ROC, receiver operating characteristic) was used to quantify the screening performance. A logistic regression analysis was used to create two new keratoconus prediction models based on these waveform parameters to resample the clinically established keratoconus indices from Pentacam and TMS-5. Results. ROC curves show the best results for the waveform parameters p1area, p2area, h1, h2, dive1, mslew1, aspect1, aplhf, and dslope1. The new keratoconus prediction model to resample the Pentacam topographic keratoconus index (TKC) was WFTKC = −4.068 + 0.002 × p2area − 0.005 × dive1 − 0.01 × h1 − 2.501 × aplhf, which achieves a sensitivity of 90.3% and specificity of 89.4%; to resample the TMS-5 keratoconus classification index (KCI) it was WFKCI = −3.606 + 0.002 × p2area, which achieves a sensitivity of 75.4% and a specificity of 81.8%. Conclusion. In addition to the biomechanically provided Keratoconus Index two new indices which were based on the topographic gold standards (either Pentacam or TMS-5) were created. Of course, these do not replace the original topographic measurement.

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.

Effects of Atopic Syndrome on Keratoconus

To evaluate the effects of atopic syndrome on manifestations of keratoconus. In this retrospective study, we reviewed patient files and data generated by Scheimpflug imaging of 670 eyes of 434 keratoconus patients. Patients were divided into a study group consisting of patients suffering from atopic syndrome (110 eyes of 75 patients), namely allergic asthma, atopic dermatitis, and/or allergic rhinitis, and a control group of patients without known atopic syndrome (560 eyes of 359 patients). We found a significant difference with the mean age being 36.1 ± 11.7 for the control group, 32.8 ± 9.6 for the atopic group (P = 0.002) with 1 atopic trait, and 30.4 ± 7.5 for patients with 2 or more atopic traits (P = 0.002). No statistically significant differences were found in the mean corrected distance visual acuity, corneal pachymetry, minimum relative pachymetric progression (RPImin), mean refraction, keratoconus index, anterior chamber depth and volume, Kmax, and location of Kmax in relation to the corneal apex. However, we found a significantly higher corneal density for the anterior 120 μm of the cornea in the atopic group (control: 20.74 ± 4.68, atopic group: 21.92 ± 4.65 P = 0.016). Keratoconus patients suffering from atopic syndrome were significantly younger but showed no topographical changes except in corneal densitometry compared with keratoconus patients without an atopic disease. This suggests atopic syndrome is a factor, which can trigger earlier manifestation of keratoconus.

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.].