Keratoconic Eyes Research Articles

Comparison of corneal biomechanical properties in healthy thin corneas with matched keratoconus eyes.

To compare corneal biomechanical parameters of normal thin corneas with matched keratoconus eyes. Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Cross-sectional comparative study. Dynamic corneal response parameters of Corvis ST were compared in 61 eyes with keratoconus with 61 matched healthy thin corneas (corneal thinnest point <500 μm), while corneal thickness, biomechanically corrected intraocular pressure, and age were considered covariates. The receiving operator sensitivity curve analysis was used to determine the cutoff point with the highest sensitivity and specificity, and the area under the curve (AUC) for each parameter. All biomechanical parameters were statistically significant between the 2 groups except for the first ( P = .947) and second ( P = .582) applanation length, first ( P = .783) and second ( P = .301) applanation velocity, and deformation amplitude in the highest concavity phase ( P = .106). The highest mean difference between groups (12.89 ± 2.03 mm Hg/mm) was related to the stiffness parameter at the first applanation (SPA1). Although the Corvis biomechanical index and tomographic biomechanical index had the highest detection ability based on their AUC (0.912 and 0.959, respectively), among the standard and combined biomechanical parameters except for keratoconus screening parameters, the highest discriminative ability was related to SPA1 with AUC, sensitivity, and specificity of 0.793, 60.66%, and 90.16%, respectively. Keratoconus corneas were significantly softer compared with healthy thin corneas of matched thickness. Optimal cutoff points close to the maximum value defined for screening parameters limit their clinical use for differentiation purposes in these particular types of cases.

Asymmetric Intrastromal Corneal Ring Segments with Progressive Base Width and Thickness for Keratoconus: Evaluation of Efficacy and Analysis of Epithelial Remodeling

Purpose: The aim of this study is to describe visual outcomes and epithelial remodeling following the implantation of asymmetric intracorneal ring segments (ICRSs) of variable thickness and base width for the management of duck-type keratoconus. Methods: A prospective observational study of patients with duck-type keratoconus was conducted. All patients received one ICRS AJL PRO + implant (AJL Ophthalmic). We analyzed demographic and clinical data, anterior segment optical coherence tomography (AS-OCT) data and Scheimpflug camera images obtained with a Placido disc MS-39 (CSO, Firenze, Italy) one and six months after surgery to determine keratometric and aberrometric outcomes and epithelial remodeling. Results: We studied 33 keratoconic eyes. ICRS implantation significantly improved both corrected distance visual acuity (CDVA) and uncorrected distance visual acuity at six months, as assessed with the logMAR (minimum angle of resolution) system, from 0.32 ± 0.19 to 0.12 ± 0.12 (p < 0.001) and from 0.75 ± 0.38 to 0.37 ± 0.24 (p < 0.001), respectively. Overall, 87% of implanted eyes gained ≥ 1 line of CDVA, and 3% of patients (n = 1) lost one line of CDVA; 55% of eyes attained a manifest refraction spherical equivalent between +1.50 and -1.50 D. Epithelial remodeling was greater at the wider and thicker end (+11.33 µm ± 12.95; p < 0.001 relative to the initial value) than at the narrower and thinner end (+2.24 µm ± 5.67; p = 0.01). Coma aberration was significantly reduced from 1.62 ± 0.81 µm to 0.99 ± 0.59 µm (p < 0.001). Conclusions: AJL-PRO + ICRS implantation for duck-type keratoconus improves refractive, topographic, aberrometric and visual parameters and induces progressive epithelial thickening along the segment.

Artificial intelligence-assisted diagnosis of ocular surface diseases.

With the rapid development of computer technology, the application of artificial intelligence (AI) in ophthalmology research has gained prominence in modern medicine. Artificial intelligence-related research in ophthalmology previously focused on the screening and diagnosis of fundus diseases, particularly diabetic retinopathy, age-related macular degeneration, and glaucoma. Since fundus images are relatively fixed, their standards are easy to unify. Artificial intelligence research related to ocular surface diseases has also increased. The main issue with research on ocular surface diseases is that the images involved are complex, with many modalities. Therefore, this review aims to summarize current artificial intelligence research and technologies used to diagnose ocular surface diseases such as pterygium, keratoconus, infectious keratitis, and dry eye to identify mature artificial intelligence models that are suitable for research of ocular surface diseases and potential algorithms that may be used in the future.

Collagen type XII is undetectable in keratoconus Bowman’s layer

PurposeCorneal biomechanical failure is the hallmark of keratoconus (KC); however, the cause of this failure remains elusive. Collagen type XII (COL12A1), which localises to Bowman’s layer (BL), is thought to...

Corneal Crosslinking With Riboflavin and UVA Light in Progressive Keratoconus: Fifteen-Year Results

To analyze the 15-year results of corneal crosslinking (CXL) in progressive keratoconus. Retrospective follow-up analysis of interventional study patients. This study included keratoconic eyes with progressive disease treated from 2001 to 2006 at the Department of Ophthalmology, Carl Gustav Carus University Hospital, TU Dresden, Germany. CXL was performed by applying riboflavin and ultraviolet A (UVA) light according to a standard protocol. The best-corrected distance visual acuity (BCVA), slitlamp examination, and corneal topography as well as corneal thickness values were recorded preoperatively and 15 years after the treatment. A total of 42 eyes received a complete follow-up of 15 years. The mean age of the patients at baseline was 26.9 (95% CI: 25.0-28.8) years. The maximum keratometry was 61.6 (95% CI: 58.2 - 64.9) diopters (D) preoperatively and 55.1 (95% CI: 51.6-58.4) D postoperatively; the decrease was statistically significant (P < .001). The mean keratometry value changed from 50.3 (95% CI: 48.3-52.4) D to 47.5 (95% CI: 45.3-49.4) D (P < 0.001). Furthermore, the thinnest corneal thickness decreased statistically significantly by 40 (95% CI: 24-56) µm (P < .001). The BCVA improved statistically significantly from 0.4 to 0.2 logMAR after the treatment. Retreatment was needed in 14% of cases. Mild scarring of the superficial stromal corneal layers was observed in 36% of the eyes, and in 67% of them visual acuity was stable or even improved. The CXL procedure proved to be an effective method in the treatment of keratoconic eyes in the progressive stage of the disease, and achieved long-term stabilization without the occurrence of serious complications or side effects.

Corneal Ectasia detection by epithelium pattern standard deviation from optical coherence tomography.

To test the ability of the corneal epithelial pattern standard deviation to distinguish between normal and cases with corneal ectatic condition. Instituto de Olhos Renato Ambrósio, Rio de janeiro, Brazil. Cross-sectional retrospective study. Patients were stratified into four groups based on clinical data and. (Groups 1 and 2 comprised one eye randomly selected from 105 patients with normal corneas (N) and 86 patients with bilateral keratoconus (KC). Groups 3 and 4, respectively comprised 11 ectatic eyes with no surgical treatment for keratoconus (VAE-E) from patients whose fellow eyes (61) presented with normal topographic patterns (VAE-NT). Corneas were scanned using an OCT system (RT Vue) and Scheimpflug corneal tomography (Pentacam), and also had biomechanical assessment through the Corvis ST. Corneal epithelial thickness maps were analyzed and the pattern standard deviation (PSD) value was calculated. The area under the ROC curve analysis was used to evaluate the diagnostic accuracy of the indices. Epithelial PSD was significantly different across the four groups (p<0.0001). The pairwise comparison revealed that the normal group presented significantly lower values than both ectasia groups (KC and VAE-E, p<0.0001) and the VAE-NT group (p=0.0008). There was no significant difference between KC and VAE-E (p=0.4284), while they were significantly higher than the VAE-NT group (p<0.0001 and p=0.0004). Epithelial PSD can be used to detect abnormal epithelial thickness patterns. Corneal epithelial thickness changes could be detected accurately in keratoconus patients, even in the form fruste of the disease.

Retracted: The association between keratoconus and allergic eye diseases: A systematic review and meta-analysis.

Retracted: The association between keratoconus and allergic eye diseases: A systematic review and meta-analysis.

Spherical equivalent pre- and post-implantable collamer lens implantation in patients with myopia, hyperopia, and stable keratoconus.

Refractive errors are common in Saudi Arabia and keratorefractive surgeries are usually done to correct them. However, not all patients are fit and complications postoperatively are a concern. Implantable collamer lens (ICL) implantation can be used for patients who are not fit for keratorefractive surgeries. ICL can also be used for keratoconus. We elected to evaluate the outcomes of patients who had ICL implantation for refractive errors or keratoconus. We retrospectively reviewed patients aged between 21 and 45 years old, who attended the anterior segment clinic at King Khaled Eye Specialist Hospital and who had spherical equivalent (SE) ranging between (+16 to -23 diopters), and had ICL implantation between February 2015 and September 2017. The SE was documented before and after the surgery. Depending on the SE, patients were divided into two groups (myopia and hyperopia). Statistical analysis was done to evaluate the change in mean SE before and after surgery for patients. We identified 169 eyes and 155 (92%) were myopic before the surgery. Before surgery, the mean SE was -8.6 and the standard deviation (SD) was 4.4. Only 14 eyes (8%) were hyperopic before the surgery with a mean SE of +5.5 and SD of 4.8. The difference in the mean of SE between after and before the surgery for myopic eyes was statistically significant (mean difference: 7.8, SD: 5, P < 0.0001). The difference in the mean of SE between post- and pre-operatively was also significant for hyperopic eyes (mean difference: -6.1, SD: 5.2, P = 0.0007). In 32 eyes with keratoconus, the mean SE before surgery was -7.9 with an SD of 4.1. For the keratoconus eyes, the mean difference of SE between after and before surgery was statistically significant as the mean difference in SE was 7.2 with an SD of 4.6 (P < 0.0001). The effect of ICL implantation was significant in improving the SE for myopic, hyperopic, and keratoconus eyes.

Stratification of keratoconus progression using unsupervised machine learning analysis of tomographical parameters

PurposeThis study aimed to stratify eyes with keratoconus (KC) based on longitudinal changes in all Pentacam parameters into clusters using unsupervised machine learning, with the broader objective of more clearly defining the characteristics of KC progression. MethodsA data-driven cluster analysis (hierarchical clustering) was undertaken on a retrospective cohort of 1017 kC eyes and 128 control eyes. Clusters were derived using 6-month tomographical change in individual eyes from analysis of the reduced dimensionality parameter space using all available Pentacam parameters (406 principal components). The optimal number of clusters was determined by the clustering's capacity to discriminate progression between KC and control eyes based on change across parameters. One-way ANOVA was used to compare parameters between inferred clusters. Complete Pentacam data changes at 6, 12 and 18-month time points provided validation datasets to determine the generalizability of the clustering model. ResultsWe identified three clusters in KC progression patterns. Eyes designated within cluster 3 had the most rapidly changing tomographical parameters compared to eyes in either cluster 1 or 2. Eyes designated within cluster 1 reflected minimal changes in tomographical parameters, closest to the tomographical changes of control (non-KC) eyes. Thirty-nine corneal curvature parameters were identified and associated with these stratified clusters, with each of these parameters changing significantly different between three clusters. Similar clusters were identified at the 6, 12 and 18-month follow-up. ConclusionsThe clustering model developed was able to automatically detect and categorize KC tomographical features into fast, slow, or limited change at different time points. This new KC stratification tool may provide an opportunity to provide a precision medicine approach to KC.

Is there a relationship between keratoconus and ocular Demodex mites?

The background of this study was to evaluate the relationship between keratoconus (KC) occurrence and ocular Demodex infestation together with the effects of Demodex on the ocular surface. Thirty-eight eyes of 20 KC patients (KC group) and 40 eyes of 20 age- and sex-matched healthy subjects (control group) were included in this cross-sectional study. Demodex species (folliculorum/brevis), clinical symptoms such as eye rubbing, Ocular Surface Disease Index (OSDI), corneal topography findings, tear break-up time (TBUT), and Schirmer test scores were evaluated. KC eyes were also divided into two subgroups according to KC severity and presence of Demodex. Demodex was detected using conventional light microscopy. The mean age was 25.90 ± 7.01 years in the KC group, and 26.52 ± 8.94 years in the control group (P = 0.731). While unexpectedly no Demodex were detected in the control group, Demodex were detected in the KC group, including 8 eyes (21.1%) with Demodex folliculorum, and 10 eyes with D. folliculorum + Demodex brevis (26.3%) (P < 0.001). As the KC severity worsened, the percentage of eyes with Demodex mites increased (43.8% in the mild/moderate subgroup and 66.7% in the severe subgroup, P < 0.001). The number of rubbing eyes and OSDI scores were significantly higher, and TBUT levels were significantly lower in the KC Demodex + and Demodex - subgroups than the control group (P < 0.001 for all), but there is no significant difference between the KC Demodex + and Demodex - subgroups regarding ocular surface parameters (P = 1.0). Although the number of patients is relatively small and there is no follow-up data after Demodex treatment, KC and ocular Demodex infestation seem to be associated. Demodex-related inflammation and associated eye rubbing may contribute to KC progression.

Comparison between MyoRing and 355°KERATACx in the management of keratoconus

Background Intracorneal implants have been proposed over the years as a possible easier way for managing keratoconus, having a favorable influence on the course of the disease. KERATACx is a relatively new form of intracorneal ring segments that has been recently introduced but not thoroughly studied regarding its safety and efficacy. Moreover, implanting a complete intrastromal ring into a corneal pocket, MyoRing (Dioptex GmbH, Austria), is an alternative technique, which can be considered safe, effective, and relatively easy for the treatment of keratoconus. Aim To compare between the effect of MyoRing and KERATACx corneal implants as new modalities of treatment on the visual acuity, as well as assess corneal topography findings in cases with moderate to severe keratoconus. Patients and methods Our study is a prospective comparative study conducted at specialized eye centers in Cairo. A total of 20 keratoconic eyes were eventually recruited. Overall, 10 of those eyes had 355° intracorneal ring segment implants (KERATACx ring segments) inserted into a femtosecond laser-created corneal tunnel at a depth of 75% of the thinnest location at the proposed tunnel site (group A), whereas the other 10 eyes had complete ring (MyoRing) implantation into a femtosecond laser-created corneal pocket at a 300-μm corneal depth (group B), by the same designated surgeon. The study was approved by the Ethics Committee of Ain-Shams University. Results Both types were proven to be statistically effective, with no statistically significant differences between the two groups related to any of the followed up parameters. In fact, both proved safe, effective, and reliable methods for managing keratoconus, with no difference of importance even to the degree of myopic refractive error correction. There were no significant intraoperative or postoperative complications reported within both groups throughout the whole study and follow-up period, but in turn, stability of the achieved results was found in both groups. Conclusion Both MyoRing and KERATACx were found to be equally effective, safe, and reliable methods for keratoconus management.

Online survey about keratoconus management by optometrists.

The aim of the study was to survey keratoconus management by optometrists in India. A validated online survey questionnaire was circulated to all optometrists from India who had completed 4 years of optometry programs. Practitioners were asked general contact lens practice questions and keratoconus management-related questions. For analysis, data were imported into SPSS (IBM Corp. 2011). A total of 159 optometrists responded to the questionnaire, of whom 10.7% of practitioners had >10 years of experience and the remaining 89.3% had <10 years. Only 45.3% of respondents had corneal topography in their practice. Approximately 55% of practitioners prescribed gas permeable (GP) lenses. Around 77.4% of practitioners considered that a combination of multiple factors is necessary for keratoconus investigations. In addition, 91.8% of practitioners used the keratoconus severity classification. Also, 73% of practitioners consider that GP contact lens (CL) fitting is more difficult in keratoconic eyes than in healthy eyes. The average number of GP diagnostic lenses used in keratoconus CL fittings was 3.93 ± 1.92. A majority of practitioners calculate back optic zone radius (BOZR) using the manufacturer's guidelines (based on manual keratometry [39.6%] or based on corneal topography [40.3%]). Around 40.3% of respondents prefer to refer patients to another optometrist for CL fitting before consulting an ophthalmologist for surgical intervention. Finally, half of the respondents participate in co-management with ophthalmologists after surgical treatment (54.1%). This study provides details about the management of keratoconus by optometrists in India. Keratoconus patient care could be improved with new evidence-based guidelines for the management and referral of these patients that would provide guidance on GP CL fitting procedures. Furthermore, it determines referral criteria and enhances co-management between optometrists and ophthalmologists.

MicroRNA Profiling in the Aqueous Humor of Keratoconus Eyes.

To identify differentially expressed (DE) microRNAs (miRNAs) in the aqueous humor (AH) of keratoconus (KC) eyes using next-generation sequencing and to explore whether DE miRNAs might play roles in KC pathophysiology. The small RNAs in the AH of 15 KC eyes and 15 myopia eyes (the control group) were sequenced on an Illumina NovaSeq 6000 platform. Gene Oncology and Kyoto Encyclopedia of Genes and Genome enrichment analyses were performed. Receiver operating characteristic curves were used to identify potential KC biomarkers. We identified 204 miRNAs in the AH of the KC group and 200 in the AH of the control group. Fourteen miRNAs were differentially expressed between the two groups; four miRNAs were upregulated and 10 downregulated in KC AH. The possible pathways regulated by the DE miRNAs included antigen processing and presentation, endocytosis, mismatch repair, and Hippo signaling. The AH concentrations of miR-222-3p, miR-363-3p, and miR-423-5p exhibited areas under the curves of 1. We profiled the DE miRNAs of the AH of KC eyes. These miRNAs may be associated with KC pathogenesis and could serve as KC biomarkers. Data on aberrantly expressed miRNAs in KC combined with bioinformatics analyses suggest possible roles for specific miRNAs. The DE miRNAs may serve as diagnostic KC biomarkers.

Penetrating Keratoplasty Versus Deep Anterior Lamellar Keratoplasty for Advanced Stage of Keratoconus

To compare visual acuity, refractive error, and complications after penetrating keratoplasty (PK) versus deep anterior lamellar keratoplasty (DALK) in the management of advanced stage of keratoconus. Retrospective, comparative, interventional study. This study enrolled 411 consecutive keratoconus eyes with preoperative mean keratometry ≥60 D that received either PK (218 eyes) or DALK (193 eyes). The outcome measures were postoperative visual acuity, refraction, complications, and further surgical interventions. The mean follow-up duration was 77.9±46.5 and 72.9±47.8 months in the PK and DALK groups, respectively (P=0.28). Compared to baseline values, postoperative visual acuity and refraction significantly improved in both groups. Postoperative corrected distance visual acuity was 0.18±0.13 and 0.26±0.19 logMAR in the PK and DALK groups, respectively (P<0.001). Postoperative spherical equivalent refraction was -2.89±2.89 D after PK and -4.58±3.62 D after DALK (P<0.001). Final keratometric astigmatism was comparable between the two groups (P=0.82). Suture-related complications were observed in 48.6% of the PK eyes and 72.0% of the DALK eyes (P<0.001). The incidence of graft rejection was 33.5% after PK and 19.7% after DALK (P=0.002). At the last visit, 98.2% of PK grafts and 94.8% of DALK grafts remained clear (P=0.06). Both techniques of corneal transplantation led to a significant improvement in the visual and refractive variables in eyes with advanced keratoconus. PK resulted in a better visual acuity and refraction with less suture-related complications compared to DALK. However, PK was associated with higher rate of graft rejection. The two techniques were comparable in terms of graft survival.

Evaluation of Anterior and Posterior Corneal Higher Order Aberrations for the Detection of Keratoconus and Suspect Keratoconus

To investigate the application of anterior and posterior corneal higher-order aberrations (HOAs) in detecting keratoconus (KC) and suspect keratoconus (SKC). A retrospective, case-control study evaluating non-ectatic (normal) eyes, SKC eyes, and KC eyes. The Sirius Scheimpfug (CSO, Italy) analyses was used to measure HOAs of the anterior and posterior corneal surfaces. Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated. Two-hundred and twenty eyes were included in the analysis (normal n = 108, SKC n = 42, KC n = 70). Receiver operating characteristic (ROC) curve analysis revealed a high predictive ability for anterior corneal HOAs parameters: the root mean square (RMS) total corneal HOAs, RMS trefoil, and RMS coma to detect keratoconus (AUC &gt; 0.9 for all). RMS Coma (3, ±1) derived from the anterior corneal surface was the parameter with the highest ability to discriminate between suspect keratoconus and normal eyes (AUC = 0.922; cut-off &gt; 0.2). All posterior corneal HOAs parameters were unsatisfactory in discriminating between SKC and normal eyes (AUC &lt; 0.8 for all). However, their ability to detect KC was excellent with AUC of &gt;0.9 for all except RMS spherical aberrations (AUC = 0.846). Anterior and posterior corneal higher-order aberrations can differentiate between keratoconus and normal eyes, with a high level of certainty. In suspect keratoconus disease, however, only anterior corneal HOAs, and in particular coma-like aberrations, are of value. Corneal aberrometry may be of value in screening for keratoconus in populations with a high prevalence of the disease.

Comparative analysis of posterior cornea between hydrops in keratoconus and Haab's striae in primary congenital glaucoma

AbstractPurpose: More eyes with keratoconus (KC) require keratoplasty after hydrops when compared to those after haab striae in primary congenital glaucoma (PCG). To compare descemet's membrane (DM) tear morphology in KC and PCG eyes using ASOCT and histopathology.Methods: ASOCT of KC eyes with hydrops (n = 12) and PCG eyes with Haab's striae (n = 15) were evaluated and compared with healthy eyes (n = 14) for descemet's membrane/ pre‐descemet's layer (DM‐PDL) morphology. These features were also assessed on histopathology of corneal button obtained from KC eyes (n = 14) and PCG (n = 13) after keratoplasty and compared with control tissues (retinoblastoma not involving cornea, n = 6) on light microscopy and immunostaining.Results: ASOCT showed thinner DM‐PDL in KC eyes(47.1 ± 25.5 μ) than that of PCG (77.2 ± 26.2 μ) (p = 0.01) inside areas of healed hydrops/ Haab's striae. DM‐PDL detachment was seen in 90% of KC eyes and 26% of PCG eyes. The height and angle of DM‐PDL detachment of KC eyes was more than that of PCG eyes. Similar to ASOCT findings, histopathology showed thinner DM‐PDL in KC eyes (62.6 ± 57.3 μ) compared to PCG (80.3 ± 78.7 μ) inside areas of healed hydrops/ Haab's striae but thicker than that of controls (32.6 ± 7.8 μ) (p‐0.01).Conclusions: Lesser fibroproliferative response and greater height of detachment ensure a poor healing after acute DM/ PDL tears in KC. This differential response of the posterior cornea may be responsible for greater need for keratoplasty in KC versus in PCG.

Systematic detection of keratoconus in OCT: corneal and epithelial thickness maps.

To detect keratoconus (KC) only by analyzing the corneal and epithelial map parameters and patterns in optical coherence tomography (OCT). Tertiary care refractive surgery center. Retrospective data collection. Corneal and epithelial thickness maps of normal, manifest, and subclinical keratoconic eyes (according to the Belin-Ambrosio display, Pentacam) were evaluated using spectral-domain OCT (Zeiss Cirrus 5000 HD). A new 2-step decision tree was developed based on previous studies with another OCT device. In the first step, if at least 1 of the 4 independent parameters (pachymetry minimum, pachymetry minimum-median, pachymetry superonasal-inferotemporal, and epithelial superonasal-inferotemporal) overruns the cutoff values, the eye was suspicious for KC. In the second step, if the epithelial map showed concentric thinning and the thinnest point of the cornea and epithelium is coincident, the eye was classified as keratoconic. 172 manifest keratoconic eyes (108 patients), 21 subclinical keratoconic eyes (20 patients), and 172 normal eyes (90 age-matched participants) were included in this study. Step 1 captured 100% of manifest and subclinical keratoconic eyes. Step 2 ruled out all suspicious but normal cases and, falsely, 2 subclinical keratoconic eyes. Our 2-step decision tree reached 100% specificity, 100% sensitivity in manifest KC, and 90.4% sensitivity in subclinical KC. Pachymetric and epithelial map parameters and patterns in OCT can be used in the diagnosis of KC, including subclinical cases, yielding a high level of agreement with the commonly used diagnostic reference, the Belin-Ambrosio display. Further improvements by refining our algorithm and including an automated evaluation in the software are desirable.

COMPARATIVE EVALUATION OF SCHEIMPFLUG TOMOGRAPHY PARAMETERS BETWEEN THIN NON-KERATOCONIC, SUBCLINICAL AND MILD KERATOCONIC CORNEAS

This paper aimed to analyze the keratometric, topometric and pachymetric featuresof keratoconic suspect and clinical keratoconic eyes from normal thin ones using a Scheimpflugimaging camera.

Comparison of anterior segment parameters in normal and keratoconus eyes using combined placido-disk schiempflug imaging-based topography

The aims: The purpose of this study was to evaluate and compare the anterior and posterior corneal surface parameters, keratoconus indices, thickness profile data, and data from enhanced elevation maps of keratoconus and normal corneas using Combined Placido-Schiempflug imaging-based topography, and to determine the sensitivity and specificity of these parameters in discriminating keratoconus from normal eyes.&#x0D; Materials and methods: A retrospective comparative observational study of 100 normal eyes and 100 keratoconus eyes was done from April 2014 to May 2015 at MM Joshi Eye Institute, Hubli, Karnataka. We evaluated and compared the anterior and posterior corneal surface parameters, keratoconus indices, thickness profile data, and data from enhanced elevation maps of keratoconus and normal corneas using Combined Placido-Scheimpflug Imaging based Topography to determine the sensitivity and specificity of these parameters in discriminating keratoconus from normal eyes.&#x0D; Results: Keratoconus indices (Sif, Sib, BCV-f, BCV-b, KVf, KVb, CCT, MinCT) showed Excellent AUROC values followed by K- steep in posterior curvature at 3 mm, 5 mm followed by K- steep in anterior curvature and other parameters in discriminating Normal from Keratoconus-Suspect eyes. Elevation indices- BCV-f, BCV-b, CCT, Min-CT, K-steep &amp; K-flat in anterior and posterior curvature in 3 mm, 5 mm, 7 mm, and CV were significant in discriminating normal from mild keratoconus. All parameters except ACV and ICA were significant in discriminating normal from moderate keratoconus. All parameters were significant in discriminating normal from severe keratoconus eyes. Morphological indices were significant in differentiating mild, moderate and severe keratoconus.&#x0D; Conclusion: Many parameters were statistically significant between keratoconus and normal eyes compared with early keratoconus eyes.&#x0D; The topography and corneal aberration results in this study are promising for detecting ectatic corneas. In our study, thickness indices-CCT, MinCT, Abberometry indices- BCVf, BCVb and keratometry in steep meridian at posterior curvature had the highest AUC scores in differentiating normal from sub-clinical keratoconus.&#x0D; Elevation indices- Rbf-f, Rbf-b, thickness indices- CCT, MinCT, aberrometry indices, and keratometry-steep in anterior &amp; posterior curvature had the highest AUC scores in differentiating moderate and severe keratoconus

Revisiting the oil droplet sign in keratoconus: Utility for early keratoconus diagnosis and screening.

An annular dark shadow (ADS) reflex has been observed while performing direct ophthalmoscopy on subjects with keratoconus. This study describes a method that may serve as a diagnostic technique for early keratoconus and may be used as a quantitative measure of severity. Healthy keratoconic subjects and keratoconus suspects underwent corneal tomography and a full ocular examination. Keratoconus severity was graded based on Belin ABCD criteria. An iPhone camera was connected to a direct ophthalmoscope to take a picture of the eye. The height of the ASD was measured using the AutoCAD software. Differences between subject groups were evaluated by chi-squared and Mann-Whitney tests. Spearman correlation compared ocular parameters and the height of the ADS. A multiple stepwise linear regression was used to predict the height of the ADS based on clinical parameters. Fifty-eight subjects participated in this study: 37 healthy controls (37 eyes) and 21 keratoconics or keratoconus suspects (37 eyes). The ADS was present in all keratoconic and keratoconus-suspect eyes but in none of the controls. The height of the ADS was significantly correlated with keratoconus severity. Front corneal surface root mean square of higher order aberrations, sphere and anterior radius of curvature from the front apex curve are significant predictors of the height of the ADS. The ADS may be a useful method to diagnose keratoconus and keratoconus-suspect cases and serve as a grading and follow-up method for tracking disease severity.