Stages Of Keratoconus Research Articles

Results at 7 years after cross-linking procedure in keratoconic patients

Long-term evaluation of functional results based on visual acuity, keratometry, spherical equivalent and refractive cylinder in patients with progressive keratoconus treated with corneal collagen cross-linking (CXL). We studied a group of 114 eyes of 91 consecutive patients treated from 2006 to 2009 by "Epi-off type" CXL. In the preoperative period, all patients had a complete ophthalmologic examination. The inclusion criteria were: patients aged 15 to 54years, with various stages of keratoconus, with a corneal thickness of at least 400μm at the thinnest point. The exclusion criteria were: patients with a corneal thickness of less than 400μm at the thinnest point, with Vogt's striae or herpetic keratitis, dry eye syndrome or aphakia. The patients were then followed at 1, 3 and 6months, and then every year between 1 and 7years postoperatively. There was a decrease in the minimum K and maximum K, respectively 1.6 and 2.0, at 7years postop. (P<0.05). The cylinder decreased from -4.45 D to -3.50 D at 7 years postop (P<0.05). The spherical equivalent decreased by 1.66 D at 7 years (P<0.05). Uncorrected visual acuity increased from an average of 0.78 to 0.679 log MAR (P<0.05) at 7 years postop. The best-corrected visual acuity increased from a mean of 0.64 to 0.52 log Mar (P<0.05) at 7 years postop. The results of CXL were stable at 7 years in all patients, consisting of reduction of keratometric values and refraction, and improvement in visual acuity.

Cataract Surgery in Patients with Keratoconus: Pearls and Pitfalls.

Background:Keratoconus (KC) is a common ectatic disorder resulting in progressive corneal thinning and irregular astigmatism. It has been observed that patients affected by KC are more likely to develop lens opacities earlier compared to non-keratoconic patients.Objective:Intraocular lens (IOL) selection and refractive outcome prediction are among a number of factors that can make cataract surgery in keratoconic patients challenging. Accurate biometry is often difficult to obtain due to unreliable K measurements and lack of dedicated biometric formulae. The use of toric IOLs has also been investigated.Conclusions:Determining the stage of KC, pre-operative patient counselling and the preferred method of refractive correction are all crucial to obtain successful postoperative outcomes and good patient satisfaction. The use of toric IOLs can achieve good results only in selected low-grade keratoconic eyes.

Endothelial alterations in 712 keratoconus patients.

To investigate the effect of the severity of keratoconus on the corneal endothelium using specular microscopy. Seven hundred and twelve eyes from the Homburg Keratoconus Center (HKC) database were included in this retrospective study. Corneal endothelium was evaluated using the Tomey EM-3000 specular microscope. Keratoconus-related topographic and tomographic data were obtained from Scheimpflug-based tomography (Oculus Pentacam® HR). Eyes were classified into stages 0 (healthy) to 4 (severe keratoconus) according to the Topographic Keratoconus Classification (TKC). Subgroups were analysed based on contact lens (CL) type (none/rigid/soft). The frequencies of keratoconus stages 0/1/2/3/4 according to TKC were 169/94/206/166/77. The endothelial cell density (ECD) for the endothelial cell area for TKC 0/1/2/3/4 was 2611/2624/2557/2487/2401 cells per mm² and the coefficient of variation (CV) was 40.9/40.0/41.6/46.2/49.0%, respectively. The more severe the keratoconus stage, the lower the endothelial cell count (p<0.001) and the higher the CV (p<0.001). No contact lens wearing was noted in 207 eyes (NoCL), rigid CL in 200 (RCL) and soft CL in 54 (SCL). CD for NoCL/RCL/SCL was 2523/2533/2644 per mm² and CV was 41.8/54.1/43.1%, respectively. A significant difference in CV was found between NoCL and RCL (p=0.02), and no significant difference in CV was found between NoCL and SCL (p=0.07). Endothelial cell density (ECD) did not differ significantly between NoCL and RCL or SCL. Endothelial cell density (ECD) decreases and CV increases significantly with increasing tomographic severity of keratoconus. In patients with RCL compared to eyes without CL wear, we found a statistically significantly higher CV in the endothelial cell size.

Comparison of 12-month anatomic and functional results between Z6 femtosecond laser-assisted and manual trephination in deep anterior lamellar keratoplasty for advanced keratoconus

The management of severe keratoconus requires corneal transplantation, for which the gold standard is deep anterior lamellar keratoplasty (DALK), preserving the healthy Descemet's membrane and endothelium. The safety and reproducibility of corneal cuts have been improved by the evolution of femtosecond lasers in refractive surgery, and femtosecond laser in DALK would seem to provide the same advantages over the manual method. In our retrospective study, we compare functional and anatomical results of femtosecond-assisted DALK versus manual trephination DALK in patients with keratoconus in stage 4 of the Krumeich classification. It is a retrospective study including all patients with stage 4 keratoconus who underwent femtosecond laser-assisted DALK between November 2012 and November 2015 in Nantes university medical center. We compared those patients to a group of patients who underwent manual DALK in the same period, paired by age and maximal keratometry. We assessed visual acuity, pachymetry, endothelial cell density (specular microscopy), and keratometry before surgery and at 4, 8 and 12months of follow-up. Laser settings and intraoperative complications were recorded. Nineteen patients underwent surgery by femtosecond-assisted DALK, 6women and 12men with average age 30.2±10.8years at transplantation. They were paired with a group of 17patients who underwent manual DALK in order to compare results. Before surgery, mean visual acuity in the femtosecond group was 0.90logMAR versus 0.89logMAR in the manual group, showing no statistically significant difference (P=0.96). Both groups were similar in terms of preoperative age, mean keratometry, pachymetry and endothelial cell density. Average visual acuity post-surgery was 0.27; 0.26; and 0.14logMAR for femtosecond DALK versus 0.27; 0.17et 0.25 for manual DALK at 4, 8 and 12months follow-up respectively, showing no statistically significant difference. After surgery, at 4, 8 and 12months, mean pachymetry was similar in both groups, and average endothelial cell density was 2390cells/mm2 for femto DALK versus 2531cells/mm2 for manual DALK at 12months of follow-up, showing no statistically significant difference (P=0.5726). The rate of Descemet's membrane microperforations during the procedure was low and similar for both groups. Our study allows for a 12-month follow-up, with assessment of visual recovery, anatomic result and endothelial safety in a series of 19femtosecond laser-assisted DALK with no statistical significant difference versus the manual trephination group. Femtosecond laser allows for increased reproducibility of the DALK procedure without reducing adverse effects during surgery. Femtosecond laser seems to improve the technique of the DALK procedure, and future developments could improve the reproducibility of DALK even further. A medical economics study would be necessary to determine the cost-effectiveness of femtosecond laser-assisted DALK.

Two Years’ Experience in Keratoconus Treatment using Collagen Cross-linking

ABSTRACT Purpose To evaluate safety, efficacy, and stability of cross-linking (CLX) procedure as a method for keratoconus treatment in the I and II stage of disease. Materials and methods Twenty eyes of 15 patients (13 males, 2 females, average age 31 years) with keratoconus I stage (13 eyes) and II stage (2 eyes) (by Krumeich classi­fication) were treated by CLX procedure, using riboflavin Medio Cross for standard CLX); riboflavin Medio Cross TE for transepithelial CLX was used to treat keratectasia after previous keratorefractive surgery; in all the cases UV CBM X linker (Vega, CSO) was used. The study included evaluation of uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) pre- and postoperative, pachymetry (central cornea thickness) (Visante OCT, Zeiss) pre- and postoperative, total astigmatism pre- and postoperative, using keratotopography (Atlas, Zeiss). Diagnosis and analysis have been performed at the International Center for Ophthalmology in Moscow, Russian ­Federation, since 2012 to 2014 years. Follow-up period was from 1 to 24 months. Results Average UCVA preoperative was 0.4 (Decimal), and average BCVA was 0.64. Average UCVA postoperative was 0.49; average BCVA was 0.66. Total astigmatism preoperative was 2.81 D; total astigmatism postoperative 2.80 D. Central cornea thickness (CCT) preoperative 454 mkm; CCT post­operative 447 mkm. Conclusion Cross-linking indicated safety, stability, and efficacy for treatment of I and II stage keratoconus at the end of follow-up period. Cross-linking is not effective in the treatment of II and III stage of disease. Further study is required. How to cite this article Dementiev D, Sysoeva M, Shipunova A. Two Years’ Experience in Keratoconus Treatment using Collagen Cross-linking. Int J Kerat Ect Cor Dis 2017;6(1):11-13.

Keratoconus diagnosis using Corvis ST measured biomechanical parameters

PurposeTo assess the diagnostic power of the Corneal Visualization Scheimpflug Technology (Corvis ST) provided corneal biomechanical parameters in keratoconic corneas. MethodsThe following biomechanical parameters of 48 keratoconic eyes were compared with the corresponding ones in 50 normal eyes: time of the first applanation and time from start to the second applanation [applanation-1 time (A1T) and applanation-2 time (A2T)], time of the highest corneal displacement [highest concavity time (HCT)], magnitude of the displacement [highest concavity deformation amplitude (HCDA)], the length of the flattened segment in the applanations [first applanation length (A1L) and second applanation length (A2L)], velocity of corneal movement during applanations [applanation-1 velocity (A1V) and applanation-2 velocity (A2V)], distance between bending points of the cornea at the highest concavity [highest concavity peak distance (HCPD)], central concave curvature at the highest concavity [highest concavity radius (HCR)]. To assess the change of parameters by disease severity, the keratoconus group was divided into two subgroups, and their biomechanical parameters were compared with each other and with normal group. The parameters' predictive ability was assessed by receiver operating characteristic (ROC) curves. To control the effect of central corneal thickness (CCT) difference between the two groups, two subgroups with similar CCT were selected, and the analyses were repeated. ResultsOf the 10 parameters compared, the means of the 8 were significantly different between groups (P < 0.05). Means of the parameters did not show significant difference between keratoconus subgroups (P > 0.05). ROC curve analyses showed excellent distinguishing ability for A1T and HCR [area under the curve (AUC) > 0.9], and good distinguishing ability for A2T, A2V, and HCDA (0.9 > AUC > 0.7). A1T reading was able to correctly identify at least 93% of eyes with keratoconus (cut-off point 7.03). In two CCT matched subgroups, A1T showed an excellent distinguishing ability again. ConclusionsThe A1T seems a valuable parameter in the diagnosis of keratoconic eyes. It showed excellent diagnostic ability even when controlled for CCT. None of the parameters were reliable index for keratoconus staging.

Acute hypoxia influences collagen and matrix metalloproteinase expression by human keratoconus cells in vitro.

Keratoconus (KC) is a progressive corneal ectasia linked to thinning of the central cornea. Hard contact lenses, rigid gas permeable lenses, and scleral lenses are the primary treatment modalities for early to mid- stages of KC to correct refractive error and astigmatism that develops as a result of an irregular corneal structure. These treatments are associated with significant drawbacks, including reduced availability of the tear film and oxygen to the corneal epithelium and stroma. However, it remains unknown whether hypoxia affects corneal integrity in the KC pathobiology. A number of studies have associated elevated oxidative stress with KC both in vitro and ex vivo. We hypothesized that KC-derived corneal fibroblasts are more susceptible to hypoxia-induced oxidative stress compared to healthy controls leading to exacerbation of corneal thinning in KC. This study investigated the effects of hypoxia on ECM secretion, assembly, and matrix metalloproteinase (MMP) expression in human corneal fibroblasts from healthy controls (HCFs) and KC patients (HKCs) in vitro. HCFs and HKCs were cultured in 3D constructs for 3 weeks and maintained or transferred to normoxic (21% O2) or hypoxic (2% O2) conditions, respectively, for 1 additional week. At the 4 week time-point, constructs were isolated and probed for Collagen I, III, and V, keratocan and MMP-1, -2, -3, -9, and -13, as well as hypoxia markers, hypoxia inducible factor-1α and lactoferrin. Conditioned media was also collected and probed for Collagen I, III, and V by Western blot. Thickness of the ECM assembled by HCFs and HKCs was measured using immunofluorescence microscopy. Results showed that hypoxia significantly reduced Collagen I secretion in HKCs, as well as upregulated the expression of MMP-1 and -2 with no significant effects on MMP-3, -9, or -13. ECM thickness was reduced in both cell types following 1 week in a low oxygen environment. Our study shows that hypoxia influences collagen and MMP expression by HKCs, which may have consequential effects on ECM structure in the context of KC.

Evaluation of Iontophoretic Collagen Cross-linking for Early Stage of Progressive Keratoconus Compared to Standard Cross-linking: A Non-Inferiority Study.

IntroductionThe purpose of this study was to evaluate the efficacy and safety of iontophoretic collagen cross-linking (I-CXL) compared to epithelium-off standard collagen cross-linking (CXL) in treating the early stages of progressive keratoconus.MethodsThis retrospective cohort study at Oftaprof Clinic, Iasi, Romania included 40 eyes of 40 patients with progressive keratoconus stage I according to the Amsler classification who underwent I-CXL and the results were compared with a matched group of 40 eyes from 40 patients who received standard CXL. The follow-up period was 24 months. Uncorrected (UCVA) and corrected (CDVA) distance visual acuities, corneal topography, and pachymetry were evaluated in all patients.ResultsThe mean patient age was 26.52 ± 3.77 years for the standard CXL group and 28.32 ± 4.91 for the I-CXL group. The mean UCVA and CDVA improved significantly in both groups. At 12 months, the improvement of UCVA was greater in the I-CXL group (P < 0.05). There was a statistically significant different trend in CDVA between groups with a more favorable outcome for the standard CXL group (P < 0.01). The manifest cylinder decreased by a mean of 0.962 ± 0.114 D in the epithelium-off CXL group and by 0.831 ± 0.082 D in the I-CXL group (P < 0.001). At 24 months, the K max values improved by 1.2 ± 0.199 D in the standard group and by 0.908 ± 0.177 D in the I-CXL group (P < 0.001).ConclusionAll parameters either improved or remained unchanged after the iontophoretic collagen cross-linking intervention. I-CXL was found to be as effective as the standard technique.Electronic supplementary materialThe online version of this article (doi:10.1007/s40123-017-0076-8) contains supplementary material, which is available to authorized users.

A correlation analysis of cone characteristics and central keratometric readings for the different stages of keratoconus

Background:Knowledge of the cone characteristics for the different stages of keratoconus may potentially assist practitioners in diagnosing and managing keratoconic patients.Aim:This study aims to determine if any correlation exists between the central keratometric readings and the cone characteristics for the different stages of keratoconus.Setting:A university eye clinic.Materials and Methods:In this retrospective study, a saturated sample of 190 eyes from 106 cases of previously diagnosed keratoconic patient files was analyzed. The stage of keratoconus and cone characteristics, namely, cone location, cone decentration, topographical patterns, and morphology were analyzed using an Oculus 3M corneal topographer.Results:Analysis revealed a correlation between cone decentration and stage of keratoconus (P = 0.007). The association was found to exist when central K-readings were between 45D and 52D and with an apical cone decentration of 3–4 mm. No correlations were obtained for the stage of keratoconus and the cone location; topography and morphology.Conclusion:It can be concluded that cone apices are not central in all stages. Practitioners should consider the peripheral cornea when diagnosing and managing keratoconic patients. No correlation between stage, morphology or topography was respectively revealed.

Corneal Cell Morphology in Keratoconus: A Confocal Microscopic Observation.

To evaluate corneal cell morphology in patients with keratoconus using an in vivo slit scanning confocal microscope. A cross-sectional study was conducted to evaluate the corneal cell morphology of 47 keratoconus patients and 32 healthy eyes without any ocular disease. New keratoconus patients with different disease severities and without any other ocular co-morbidity were recruited from the ophthalmology department of a public hospital in Malaysia from June 2013 to May 2014. Corneal cell morphology was evaluated using an in vivo slit-scanning confocal microscope. Qualitative and quantitative data were analysed using a grading scale and the Nidek Advanced Visual Information System software, respectively. The corneal cell morphology of patients with keratoconus was significantly different from that of healthy eyes except in endothelial cell density (P = 0.072). In the keratoconus group, increased level of stromal haze, alterations such as the elongation of keratocyte nuclei and clustering of cells at the anterior stroma, and dark bands in the posterior stroma were observed with increased severity of the disease. The mean anterior and posterior stromal keratocyte densities and cell areas among the different stages of keratoconus were significantly different (P < 0.001 and P = 0.044, respectively). However, the changes observed in the endothelium were not significantly different (P > 0.05) among the three stages of keratoconus. Confocal microscopy observation showed significant changes in corneal cell morphology in keratoconic cornea from normal healthy cornea. Analysis also showed significant changes in different severities of keratoconus. Understanding the corneal cell morphology changes in keratoconus may help in the long-term monitoring and management of keratoconus.

PERSONALIZED (LOCAL) UV-CROSSLINKING AS A TREATMENT OF KERATOCONUS AND CORNEAL ECTASIA

There is no doubts that problem of keratoconus treatment is high relevant. The number of diagnosed ectasia, including iatrogenic ectasia, increased — in recent years. The amount of post-LASIK and ectasia after RK in late postoperative period multiplies significantly. It is associated not only with inception of new ways of treatment into practice, but also with the upgrade of diagnostic methods and equipment. A new method of local personalized crosslinking (LCXL) was integrated into clinical practice using Laplace’s equation, pachymetry and topography maps data, It exceeds usual Dresden protocol on several parameters. This article shows the reaction of patients’ eyes on the treatment and the effectiveness of technique is provided. Materials and methods: topographic indications were evaluated (Orbscan II (B+L)) of 28 patients (40 eyes) aged 18 — 44 with keratoconus stages I-IV (12 eyes — I stage; 16 eyes — II stage; 9 eyes — III stage; 3 eyes — IV stage classified by Abugova T.D.), as well as UCVA, BCVA for 12 months after surgery. Normal values were estimated by characteristics of 30 eyes without any refractive errors. Results: LCXL is an effective way of treatment of corneal ectasia; it’s more effective in early stages. This technique has a strong controlled refractive impact and allows to reduce inflammatory after procedure.

Pupillary Offset in Keratoconus and its Relationship with Clinical and Topographical Features

ABSTRACTPurpose: To evaluate the change in the location of pupillary center with corneal tomography in keratoconic patients, and determine the correlation of pupillary offset with clinical and topographical features of keratoconus.Methods: Ninety-one eyes of the 54 patients with keratoconus in different stages and 39 eyes of 39 refractive surgery candidates with normal corneas were included in our study. Ocular aberrations and the pupillary offset parameters (x-offset and y-offset) over a 5 mm (undilated) pupil were measured with a Sirius corneal tomographer. A correlation analysis among the pupillary offset parameters and the possible determinative variables (topographical and tomographical parameters, corneal aberrations and best corrected visual acuity) was performed.Results: The mean pupillary offset was significantly greater in the keratoconic eyes compared with the controls (p = 0.003), and the difference was mostly due to the y-offset (p = 0.03). There was no significant difference between the groups in the mean horizontal pupillary offset value (p = 0.07). Both the vertical and the total pupillary offset values correlated significantly (p < 0.0001) with the keratoconus stage (r = 0.58 and r = 0.51, respectively). They also correlated with the corneal aberrations, and negatively correlated with the visual acuity.Conclusions: The pupillary offset seems to correlate with the clinical and topographic features of keratoconus. It may be important to quantify its magnitude and direction in order to ensure correct centralization of the corneal procedures.

Corneal iontophoresis and cross linking: a preliminary report of our experience.

To evaluate the effect induced by UVA radiation with corneal iontophoresis and cross-linking. From February 2013 to August 2014 we saw 15 eyes of 15 patients, age range 19-38 years (10 women and 5 men) keratoconus stage 1-2. Vision evaluation was carried out with ETDRS scale and Topography and Pachymetry. To evaluate line of demarcation with the confocal microscope and corneal optical coherence tomography (OCT) and the pain with the Faces Pain Scale. At 6 months there was a stabilization of vision and topography, with a slight improvement at 1 year of vision of 1 line and of the Km of 0.5 diopters. The in vivo microscopic examination with the confocal microscope showed that the line of demarcation was not particularly evident, it was irregular and when present was more evident at 150-200 µ depth, there was a keratinocyte activation in the anterior stroma with slight oedema. There were also superficial epithelial alterations present and only slight involvement of the subepithelial nervous plexus, there were no alterations of the endothelium. The Faces Pain Scale the pain score was 2±1. We have to stress the usefulness of Corneal optical coherence tomography (OCT) also pre and post iontophoretic treatment. Further, larger studies and longer follow-ups are needed, recent studies have shown the absorption of riboflavin with iontophoresis is 50% with respect to the classic technique, the percentage of riboflavin in the anterior 2/3 of the corneal stroma would be, however, efficacious to provide good results.

A statistical approach to classification of keratoconus

The front portion of the eye consists of a transparent layer called the cornea. The cornea is an important optical component for vision and plays a role in the specific refraction of the eye. The cornea normally has convexity but the amount of protrusion progressively increases in patients with keratoconus. In other words, the cornea prolapses forward. Keratoconus is a bilateral, typically asymmetric and non-inflammatory degeneration of the cornea caused by corneal protrusion as a result of progressive thinning of the corneal stroma. Corneal thinning generally occurs in the inferior, inferotemporal or central regions of the cornea[1]. However, corneal thinning in the upper quadrants of the cornea can also occur[2]. Corneal thinning and the following splay can cause high astigmatism and myopia, leading to degradation in visual quality, ranging from mild to severe[3]. Classification of keratoconus is the first step in approaching the disease because the severity of the disease and the stage at which the patient is diagnosed and treated affect treatment results[4]. In the past, there were multiple attempts to reach a reasonable and easily applicable keratoconus staging system, mostly based on the pattern of corneal topography and the morphology of the cone. Most of these attempts shared a common methodological fallacy, taking certain parameters into consideration based on authors' judgement. This caused, the proposed methods for staging of keratoconus were lacking some essential parameters to be incorporated into their methods. Increase and decrease in values that determine the disease may not be associated with each other, and failing to understand and compensate for this may lead to less efficient tracking of the disease. Some researchers classified keratoconus into four groups by looking only at keratometry values or using data on eyesight only, whereas others classified the disease into two groups by looking only at data pertaining to the placido disk. In this study we aimed to define a new classification method for detecting keratoconus based on statistical analysis.

Correlations Fleischer deposits with topographic parameters at different deformations of the cornea

PurposeAssessment of topographic and tensor topographic maps of the patients and the analysis of their compliance with deposits Fleischer.Methods28 patients with disorders of the biomechanics of cornea after RK, PRK, TKC, LASIK, IOL implantation, as well as using the orto‐contact lenses and degenerative changes various stages of keratoconus. All patients complemented by photos recording Fleischer corneatopography deposits and then calculating stress distribution map of the cornea –keratotenzotopogramm (KTT).ResultsThe correlation position Fleischer deposits with zones of maximum mechanical stress gradient in corneas with disabilities form as a result of various causes. Most obviously there Fleischer pigment deposits in the form of rings – after hyperopic LASIK. Position of Fleischer ring correlated with the area of corneal mechanical stress maximum gradient according keratotenzotopogrammConclusionsWe are inclined to the hypothesis that Fleischer deposits are natural markers of corneal zone, which are activated in the past or have been active processes caused by excessive mechanical stress in the cornea's stroma.

Pediatric Keratoconus in a Tertiary Referral Center: Incidence, Presentation, Risk Factors, and Treatment.

To report the incidence, clinical presentation, risk factors, and treatment outcome of pediatric keratoconus in a tertiary referral eye hospital in Beirut, Lebanon. In this retrospective study, the authors evaluated all patients with keratoconus 14 years or younger newly diagnosed at the Beirut Eye Specialist Hospital, Beirut, Lebanon, between January 2010 and December 2014. The incidence of pediatric keratoconus among all pediatric patients and among patients with keratoconus of all ages was assessed. Patients with pediatric keratoconus were evaluated for keratoconus stage, initial presentation, uncorrected distance visual acuity, corrected distance visual acuity (CDVA), corneal topography, and pachymetry. Patients were classified according to different treatment regimen groups and different follow-up visits were evaluated. During 5 years, 16,808 patients were examined, of whom 2,972 were 14 years or younger. A total of 541 patients were diagnosed as having keratoconus; of those, 16 were 14 years or younger at the time of diagnosis. Hence, the incidence of keratoconus was 0.53% among pediatric patients and 3.78% among adult patients (> 14 years). Initial presentation was during routine checkup (1 of 16) for allergic conjunctivitis (3 of 16), reduced vision (10 of 16), and corneal hydrops (mimicking keratitis) (2 of 16). Except for 2 patients lost to follow-up, all eyes received corneal cross-linking treatment and 16 eyes received additional intracorneal ring segment implantation. The incidence of pediatric keratoconus indicates that increased awareness for keratoconus among children is needed, mainly in cases of family history of keratoconus, ocular allergy/pruritus, poor CDVA, corneal hydrops, and/or high astigmatism. [J Refract Surg. 2016;32(8):534-541.].

Comparison between corneal elevation maps using different reference surfaces with Scheimpflug–Placido topographer

The purpose of this study was to compare the anterior and posterior elevation measurements using different reference surfaces (spheric, aspheric, and aspherotoric) with Scheimpflug-Placido topography in simple myopic and keratoconus patients. 600 eyes of 600 patients undergoing screening for keratorefractive surgery (500 simple myopic, 100 keratoconus stage 1 and 2) in Sohag refractive center, Egypt, were examined by Scheimpflug-Placido topography (Sirius, CSO, Italy) for both the anterior and posterior corneal elevation maps using the spheric, aspheric, and aspherotoric reference surfaces. 100 keratoconic eyes showed higher discriminating power using the aspherotoric reference surface in both the anterior and posterior elevation maps. The use of aspherotoric reference surface gives more data for eyes with keratoconus and its use is more informative in screening.

Does the Stage of Keratoconus Affect Optical Coherence Tomography Measurements?

ABSTRACTPurpose: To employ optical coherence tomography (OCT) to examine the relationship of changes in the retinal nerve fiber layer (RNFL) and macular thickness as well as ganglion cell (GC) parameters with the stage of keratoconus (KC), and to compare these changes with a control group. Methods: A total of 84 eyes of 68 patients with KC and 29 eyes of 29 normal age-matched subjects underwent RNFL, macular thickness measurements, and ganglion cell analysis using Cirrus high-definition (HD) OCT. Patients with KC were classified according to the Amsler–Krumeich Classification. The measurements were analyzed in all quadrants for each KC stage and compared with control subjects. Results: All RNFL, macular thickness, and ganglion cell parameters varied significantly among the groups (all p<0.001, analysis of variance). An increase in the stage of KC was correlated with decreased RNFL thickness, macular thickness, and ganglion cell parameters. Conclusions: RNFL, macular thicknesses, and ganglion cell parameters in all KC stages were lower than those in the control group. The RNFL, macular thickness, and ganglion cell parameters of the Grade 1 KC group were most similar to those of the control group. The severity of irregular astigmatism at the same stages of KC had a significant effect on OCT measurements. It may therefore be beneficial to know the amount of change/deviation in OCT measurements in keratoconus patients and to report which parameters exceed the standards so that OCT can be used to correlate the stage of keratoconus with the extent of the ocular disorder.

Freiburger Keratokonusregister

Keratoconus is a progressive corneal disease with thinning and scarring of the cornea. Diagnostic and treatment options are usually evaluated in large prospective or retrospective trials. Big data and smart data provide the possibility to analyze routine data for clinical research. In this article we report the generation of a monocentric keratoconus registry by means of computerized data analysis of routine data. This demonstrates the potential of clinical research by means of routine data. A "clinical data warehouse" was created from all available routine electronic data. At the time of first presentation, each eye was classified into one out of four categories: suspected, early disease, late disease and status postkeratoplasty. Through integration of multiple data sources the clinical course for each patient was documented in the registry. A total of 3681 eyes from 1841 patients were included. The median follow-up time was 0.54 years. Patient age was higher in the groups with more severe stages of keratoconus, the proportion of female patients was higher in the group of suspected keratoconus and patient age and male to female ratios showed statistically significant differences between the groups (p <0.001). We were able to create a "clinical data warehouse" by linking multiple data sources and normalizing the data. With this tool we established a novel, monocentric keratoconus registry. Only the grading of disease severity and the exclusion of false positive results were carried out manually. In our opinion establishing a structured clinical data warehouse has a huge potential for clinical and retrospective studies and proves the value of the Smart Data concept.

Forward light scatter and visual acuity before and after intrastromal corneal ring segment implantation at different stages of keratoconus.

To assess forward light scatter (stray light) before and after intrastromal corneal ring segment (ICRS) implantation at different stages of keratoconus and to examine correlation between postoperative stray light and visual acuity (VA). In 27 eyes of 27 subjects with keratoconus, stray light was determined using the compensation comparison technique before and 6months after ICRS implantation. Monocular corrected distance VA (CDVA) was measured using a high-contrast logMAR letter chart. Corneal higher-order aberrations (HOAs), contrast sensitivity (CS) and minimum corneal thickness (CT) were also measured. Mean CDVA was 0.42±0.28 preoperatively and 0.24±0.15 logMAR postoperatively (p<0.01). Mean corneal coma-like aberration decreased postoperatively (RMS 0.55±1.18μm, p<0.01). Minimum CT increased 25.31±18.59μm (p<0.01). Mean preoperative and postoperative stray light were 1.36±0.31 and 1.48±0.32 log units, respectively (p<0.01). Mean changes produced in stray light (worsening) were 0.03±0.21 (p>0.05) for stage I, 0.13±0.14 (p=0.013) for stage II and 0.18±0.21 (p=0.023) for stage III. Significant positive correlation (r=0.47, p=0.01) was detected between postoperative stray light and postoperative CDVA such that as stray light increased, CDVA worsened (higher logMAR values). Postoperative stray light was neither associated with HOAs, CS nor minimum CT. Stray light values in these patients with keratoconus were higher than normal preoperatively. In eyes with stage II and III keratoconus, stray light increased 6months after ICRS placement. Higher postoperative stray light was correlated with a worse visual acuity outcome.