Keratoconus Index Research Articles

Associations between endothelial cell characteristics and corneal topography findings in different stages of keratoconus.

This study aimed to compare and correlate specular microscope indices and corneal topography indices in different stages of keratoconus. Two hundred forty-six eyes of 123 participants were enrolled in the study. Corneal topography was performed using Sirius (CSO, Italy), with a rotating Scheimpflug camera and a Placido disc topographer. Corneal endothelial cell indices were assessed using a specular microscope (Nidek CEM-530, Japan). Eyes were graded as keratoconus stages 0-4 according to the Amsler-Krumeich classification. Corneal topography and endothelial cell indices were compared among the groups, and the correlations between them were analyzed. The mean age of the patients was 23.26 ± 6.75years (range, 14-47years). Forty-eight cases were male (39%) and 75 were female (61%). There were no statistically significant age (p = 0.578) or sex ratio (p = 0.529) differences between the groups. Twenty-nine eyes were included in the control group (11.78%), while 41 (16.67%) had stage 1 keratoconus, 88 (35.77%) had stage 2, and 88 (35.77%) had stage 3. Measurement was not possible in stage 4 keratoconus. No statistically significant difference was determined in specular microscopy values according to the stage of keratoconus, except for the number of analyzed cells (NUM) (p > 0.05). The lowest NUM values were observed in stages 1, 2, and 3, with values of 184.34 ± 67.62 cells/mm2, 155.07 ± 59.48 cells/mm2, and 127.06 ± 64.39 cells/mm2, respectively (p = 0.001). In the keratoconus group, weak statistically significant negative correlations were observed between NUM and SimK1, SimK2, KVf, BCVf, KVb, and BCVb, while a weak positive correlation was noted between NUM and central corneal thickness (p < 0.05). NUM seems to decrease, while endothelial cell density exhibits no significant changes, with the progression of keratoconus. It appears that as keratoconus index values increase, NUM may decrease in different stages of keratoconus.

Machine Learning-Based Identification of Risk Factors of Keratoconus Progression Using Raw Corneal Tomography Data.

The purpose of this study was to identify early indicators of keratoconus progression in Pentacam data using machine learning (ML) techniques. A retrospective Pentacam tabular data set was created by retrieving 11,760 tomography tests performed in patients with keratoconus. Data for eyes labeled unstable based on their referral for cross-linking were differentiated from data for eyes labeled stable and not referred for follow-up procedures. A boosted decision tree was trained on the final data set using a cross-validation method. The final labeled data set included 1218 tomography tests. Training a ML model on a single test for each eye did not accurately predict disease progression, as indicated by the mean receiver-operating characteristic area under the curve of 0.59 ± 0.1, with precision of 0.27, recall of 0.3, and F1 score of 0.28. Training on serial tests for each eye included 819 tomography scans and yielded good prognostic abilities: a receiver-operating characteristic area under the curve of 0.75 ± 0.07, precision of 0.32, recall of 0.67, and F1 score of 0.43. In addition, 4 of the 55 Pentacam raw data parameters predominantly used the algorithm decision: age, central keratoconus index, Rs B, and D10 mm pachy. This study revealed specific dominant parameters attributing to the classification of stability, which are not routinely assessed in determining progression in common practice. Using ML techniques, keratoconus deterioration was evaluated algorithmically with training on multiple tests, yet was not predicted by a single tomography test. Hence, our study highlights novel factors to the current consideration of cross-linking referral and may serve as a supportive tool for clinicians.

Diagnosis of forme fruste keratoconus with scheimpflug photography in Ghanaian patients

AimThis study aimed to differentiate moderate to high myopic astigmatism from forme fruste keratoconus using Pentacam parameters and develop a predictive model for early keratoconus detection.MethodsWe retrospectively analysed 196 eyes from 105 patients and compared Pentacam variables between myopic astigmatism (156 eyes) and forme fruste keratoconus (40 eyes) groups. Receiver operating characteristic curve analysis was used to determine the optimal cut-off values, and a logistic regression model was used to refine the diagnostic accuracy.ResultsStatistically significant differences were observed in most Pentacam variables between the groups (p < 0.05). Parameters such as the Index of Surface Variance (ISV), Keratoconus Index (KI), Belin/Ambrosio Deviation Display (BAD_D) and Back Elevation of the Thinnest Corneal Locale (B.Ele.Th) demonstrated promising discriminatory abilities, with BAD_D exhibiting the highest Area under the Curve. The logistic regression model achieved high sensitivity (92.5%), specificity (96.8%), accuracy (95.9%), and positive predictive value (88.1%).ConclusionThe simultaneous evaluation of BAD_D, ISV, B.Ele.Th, and KI aids in identifying forme fruste keratoconus cases. Optimal cut-off points demonstrate acceptable sensitivity and specificity, emphasizing their clinical utility pending further refinement and validation across diverse demographics.

AvaGen Genetic Testing versus Ocular Screening Assessments Including the Keratoconus Severity Score (KSS) and Randleman Ectasia Risk Score System (ERSS) in Refractive Surgery Candidates.

To determine whether the AvaGen (AG) Genetic Eye Test provided additional information for screening for the presence of keratoconus (KC) and assessing KC risk in refractive surgery candidates, as compared to the Keratoconus Severity Score (KSS) and Randleman Ectasia Risk Score System (ERSS). This retrospective study analyzed patients seeking refractive surgery at an eye clinic in the United States between January 2022 and July 2023. The inclusion criteria encompassed those with a family history of KC, positive KC indices, or both. Corneal evaluations and demographic information were recorded and analyzed. KSS and ERSS criteria were utilized to evaluate postoperative KC and ectasia risk, respectively. Patients were categorized on how the AG genetic test compared to KSS and ERSS criteria. Clinicians assessed topographic indices, criteria scoring, and AG testing to deliver a definitive surgical recommendation. Among the 19 patients evaluated for ectasia risk, AG testing showed lower KC risk than ocular screening in three patients (15.8%), equal risk in three patients (15.8%), and higher risk in 13 patients (68.4%). The mean AG scores were 45.7 ± 7.0, 49.0 ± 3.46, and 61 ± 13.0 for these respective categories. The most frequently identified KC risk genes were ADAMTS18, COL2A1, and COL4A1. The AG test modified the physician's recommendation for refractive surgery in nine cases (47.4%). Despite the promising application of AG testing for assessing KC risk, further research and development are needed to enhance its applicability for screening refractive surgery candidates, in addition to standard ocular screening approaches.

Alterations in Corneal Sensitivity, Staining and Biomechanics of Alopecia Areata Patients: Novel Findings in a Case-Control Study.

Background: A higher prevalence of ophthalmological alterations in systemic inflammatory diseases has been demonstrated. Objectives: Our objectives were to determine anterior segment findings and corneal properties in alopecia areata (AA). Methods: This is a case-control study. Severe AA patients (Severity of Alopecia Tool > 50%) and non-AA subjects underwent a general ophthalmological examination, a Pentacam and Corvis scheimpflug technology examination (Oculus Optikgeräte GmbH, Wetzlar, Germany). Visual acuity, refractive error, corneal aesthesiometry, and biomechanical and topographic variables were registered. Results: In total, 25 AA patients (50 eyes; 50.6 ± 8.1 years) and 29 controls (58 eyes; 49.4 ± 8.6 years) were included. AA patients had decreased corneal sensitivity, more corneal staining, and a more advanced cataract (p ≤ 0.004). The anterior topographic flat meridian, mean anterior keratometry, and maximum keratometric point were increased in AA (p ≤ 0.040), while pachymetry values were thinner (p ≤ 0.001). Keratoconus index and Belin/Ambrosio-enhanced ectasia total deviation display were increased (p ≤ 0.007). Two eyes with a topographic diagnosis of keratoconus and four eyes with subclinical keratoconus were detected in AA. Applanation lengths were smaller in AA (p ≤ 0.029). The Corvis Biomechanical Index was increased in AA (p = 0.022). Conclusions: AA patients have reduced corneal sensitivity and increased corneal staining. Topographic and biomechanical parameters are altered, and there could be a higher risk of keratoconus, thus possibly requiring routine ophthalmological examination.

Distribution of Normative Keratoconus (KC) indices for patients aged 6 to 21 Years using Pentacam HR in the Riyadh area

Objectives: To determine the distribution of Normative Keratoconus (KC) indices in normal Saudi patients aged between 6-21 years in the Riyadh area. Method: The present study employed a prospective, cross-sectional, observational, multicenter design to gather data from patients aged 6 to 21 who were seen in several non-ophthalmic emergency departments in Riyadh, Kingdom of Saudi Arabia, in 2017. Scheimpflug corneal tomography system in rotation was used to measure the cornea. Following optometric exams, corneal imaging and KC index measurements were performed using the Pentacam. Results: 366 study participants were analyzed after the exclusion criteria were applied. All children's mean and standard deviation (SD) ages were 17.41±4.83 (6–21). All the KC indices percentiles for pediatric, adolescent, and young adult groups are within normal ranges. Comparison between KC indices and age groups reveals statistically significant differences for most indices with P &lt;0.05. As the age increases, the ISV, IVA, KI, CKI, IHA, IHD, BFS Front, BFS Back, ART Min, ART Max, ART Avg, and AC Depth decrease. Also, As the age increases, the topographic astigmatism (Topo Astig), PPI Min, PPI Max, and PPI Avg increase. There was a statistically significant correlation between KC indices and age, with most indices with P &lt;0.05. The correlation coefficient ranges from 0.14 negative weak to 0.65 negative moderated, and from positive weak 0.22 to negative strong 0.82. Moreover, compression between KC indices and Topo Astig groups reveals statistically significant differences for most indices P &lt;0.05. As the Topo astig increase, the K1, RSagMin PPIMax, and PPIAvg decrease. As the Topo Astig increases, the K2, ISV, IVA, CKI, IHA, BFS Back, and ACD increase. Also, there was a statistically significant correlation between Topo Astig groups and indices with P &lt;0.05. The correlation coefficient ranges from 0.13 positive weak to 0.70 positive strong and from negative weak 0.11 to negative moderate 0.42. Conclusion: The KC indices of the current study were within normal range and comparable to prior studies. However, some indices were related to age, refractive error, and location. The normative values of multiple Pentacam indices showed statistically significant variations throughout the age groups and Topo astig subgroups.

Corneal Collagen Crosslinking for Ectasia After Refractive Surgery: A Systematic Review and Meta-Analysis.

Corneal ectasia leads to progressive irregular corneal curvature and reduced visual acuity. To assess the safety and effectiveness of corneal collagen cross-linking (CXL) for managing corneal ectasia resulting from refractive laser surgery (RSL). A systematic review and meta-analysis were realized according to PRISMA guidelines. We searched PubMed, EMBASE, Cochrane, and Web of Science databases for studies on CXL in patients with ectasia after RLS. The outcomes of interest included visual acuity, refractive outcomes, topographic parameters (Kmax, index 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 Rmin (minimum sagittal curvature)), central corneal thickness, endothelial cell count, and possible adverse events. Statistical analysis was performed using the R software (version 4.2.3, R Foundation for Statistical Computing, Vienna, Austria). 15 studies encompassing 421 patients (512 eyes) were included. The mean age was 32.03 ± 4.4 years. The pooled results showed a stable uncorrected visual acuity post-CXL, with a significant improvement in corrected distance visual acuity (SMD = 0.09; 95% CI: -0.07 to 0.26). The spherical equivalent decreased significantly (SMD = -0.09; 95% CI: -0.35, -0.02). The topographic parameter Kmax decreased significantly (SMD = 0.15; 95% CI:0.01 to 0.28); however, the other parameters, ISV, IVA, KI, CKI, IHA, IHD, and Rmin, did not change significantly. Central corneal thickness decreased significantly (SMD = 0.24; 95% CI:0.07 to 0.41), and the endothelial cell count remained stable The complications were rare. CXL is a safe and effective technique for managing corneal ectasia after RLS.

Clinical, Anatomical, and Densitometric Changes following Dresden vs. Accelerated Corneal Cross-Linking in Progressive Keratoconus.

To compare clinical, anatomical, and densitometric changes following Dresden (DCXL) vs. accelerated (ACXL) corneal UVA cross-linking (CXL; Avedro KXL, Geuder, Heidelberg, Germany) in progressive keratoconus (KC). In this retrospective study, we analyzed 20 patients following DCXL (3 mW/cm², 30 min, 5.4 J/cm²) and 44 patients following ACXL (9 mW/cm², 10 min, 5.4 J/cm²) between January 2016 and February 2020. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), steepest keratometry (Kmax), keratoconus index (KI), thinnest pachymetry (Pthin), and corneal densitometry (CD) were measured before and 3, 6, 12, and 24 months after CXL. During the follow-up period, no changes in UCVA, BSCVA, Kmax, KI, or Pthin occurred. CCT significantly decreased 3 months after DCXL (p = 0.032) and ACXL (p = 0.006). At the 12- and 24-month follow-up, CCT remained decreased in the DCXL (p = 0.035, 0.036, respectively) but not in the ACXL group. At the 12-month follow-up, the reduction in CCT was significantly greater in DCXL compared to ACXL (p = 0.012). At the 3-, 6-, 12-, and 24-month follow-ups, we found a significant increase in the anterior stroma CD following DCXL (p = 0.019, 0.026, 0.049, 0.047, respectively) but not ACXL. The CD changes were localized in the central concentric zones (0.0 to 6.0 mm). No intra- or postoperative complications occurred. ACXL and DCXL effectively halted KC progression. ACXL proved to be a safe time-saving alternative to conventional DCXL. DCXL led to a reduction in CCT and an increment in the CD of the central anterior stroma during 24 months of follow-up.

Corneal topographic indices of Scheimpflug camera in type 2 diabetic and non‐diabetic elderly population

Aims/Purpose: To determine the corneal topographic indices of Scheimpflug camera in type 2 diabetic and non‐diabetic in elderly population of Tehran, Iran.Methods: A total of 1105 subjects were selected using random cluster sampling from Tehran, Iran and categorized into two groups including diabetics and non‐diabetics. The diabetic group had HbA1c levels ≥6.4% with no other systemic problems. The non‐diabetic participants had normal eye findings and no systemic diseases. The keratometry values, Q‐value, index of surface variance (ISV), index of vertical asymmetry (IVA), central keratoconus index (CKI), keratoconus index (KI), index of height asymmetry (IHA), index of height decentration (IHD), anterior average radius of curvature (ARC), posterior average radius of curvature (PRC), and pachymetric progression index (PPI) values were measured using the Pentacam AXL.Results: A total participants included 429 diabetic (38.46% male) and 676 non‐diabetic (38.76% male). Only PPIavg and PPImax were higher in the diabetics versus non‐diabetics (p = 0.019 and p = 0.010, respectively). The HbA1c level was 5.47 ± 0.34, 6.70 ± 0.17, and 8.72 ± 1.16 in the first, second, and third group, respectively. There was a significant difference in PPImax between the three groups (p = 0.036). There were significant differences only in IVA, CKI, PPIAvg, and PPImax between different stages of DR (p = 0.045, p = 0.005, p = 0.002, and p = 0.004, respectively). The diabetic subjects were divided into two groups based on the presence of DR. There was a significant difference in ISV, IVA, PPIavg, and PPImax between diabetic subjects with and without DR (p = 0.016, p = 0.022, p &lt; 0.001, and p &lt; 0.001, respectively).Conclusions: The results of this study showed that DM and DR change several topographic indices and the HbA1c level may affect PPImax. Therefore, special attention should be paid to these patients for different treatment strategies.

Corneal topographic indices of scheimpflug camera in type 2 diabetic and non-diabetic elderly populations

PurposeThe present study was conducted to determine the corneal topographic indices of Scheimpflug camera in type 2 diabetes patients without diabetic retinopathy (DR), DR and non-diabetic elderly populations.MethodsA total of 1105 participants were selected using random cluster sampling from Tehran, Iran and categorized into three groups including type 2 diabetes patients without diabetic retinopathy (DR), DR and non-diabetic. The diabetic group had HbA1c levels ≥ 6.4% with no other systemic problems. The non-diabetic participants had normal eye findings and no systemic diseases. The pachymetric progression index (PPI) values were measured using the Pentacam AXL.ResultsA total of 1105 participants including 429 diabetes patients (38.46% male) and 676 non-diabetic (38.76% male) subjects entered the study. Only PPIavg and PPImax were higher in the diabetics versus non-diabetics (P = 0.019 and 0.010, respectively). There was a significant difference in PPImax between the three groups (P = 0.036). There were significant differences only in index of vertical asymmetry (IVA), central keratoconus index (CKI), PPI average, and PPI max between different stages of diabetic retinopathy (DR) (P = 0.045, 0.005, 0.002, and 0.004, respectively). There was a significant difference in index of Surface Variance (ISV), index of vertical asymmetry (IVA), PPIavg, and PPImax between diabetes patients with and without DR (P = 0.016, 0.022, < 0.001, and < 0.001, respectively).ConclusionAccording to the results, diabetes and DR change several topographic indices. In addition, the HbA1c level may affect pachymetric progression index max. Therefore, special attention should be paid to these patients for different treatment strategies.

Subclinical Keratoconus Detection and Characterization Using Motion-Tracking Brillouin Microscopy

To characterize focal biomechanical alterations in subclinical keratoconus (SKC) using motion-tracking (MT) Brillouin microscopy and evaluate the ability of MT Brillouin metrics to differentiate eyes with SKC from normal control eyes. Prospective cross-sectional study. Thirty eyes from 30 patients were evaluated, including 15 eyes from 15 bilaterally normal patients and 15 eyes with SKC from 15 patients. All patients underwent Scheimpflug tomography and MT Brillouin microscopy using a custom-built device. Mean and minimum MT Brillouin values within the anterior plateau region and anterior 150 μm were generated. Scheimpflug metrics evaluated included inferior-superior (IS) value, maximum keratometry (Kmax), thinnest corneal thickness, asymmetry indices, Belin/Ambrosio display total deviation, and Ambrosio relational thickness. Receiver operating characteristic (ROC) curves were generated for all Scheimpflug and MT Brillouin metrics evaluated to determine the area under the ROC curve (AUC), sensitivity, and specificity for each variable. Discriminative performance based on AUC, sensitivity, and specificity. No significant differences were found between groups for age, sex, manifest refraction spherical equivalent, corrected distance visual acuity, Kmax, or KISA% index. Among Scheimpflug metrics, significant differences were found between groups for thinnest corneal thickness (556 μm vs. 522 μm; P < 0.001), IS value (0.29 diopter [D] vs. 1.05 D; P < 0.001), index of vertical asymmetry (IVA; 0.10 vs. 0.19; P < 0.001), and keratoconus index (1.01 vs. 1.05; P < 0.001), and no significant differences were found for any other Scheimpflug metric. Among MT Brillouin metrics, clear differences were found between control eyes and eyes with SKC for mean plateau (5.71 GHz vs. 5.68 GHz; P < 0.0001), minimum plateau (5.69 GHz vs. 5.65 GHz; P < 0.0001), mean anterior 150 μm (5.72 GHz vs. 5.68 GHz; P < 0.0001), and minimum anterior 150 μm (5.70 GHz vs. 5.66 GHz; P < 0.001). All MT Brillouin plateau and anterior 150 μm mean and minimum metrics fully differentiated groups (AUC, 1.0 for each), whereas the best performing Scheimpflug metrics were keratoconus index (AUC, 0.91), IS value (AUC, 0.89), and IVA (AUC, 0.88). Motion-tracking Brillouin microscopy metrics effectively characterize focal corneal biomechanical alterations in eyes with SKC and clearly differentiated these eyes from control eyes, including eyes that were not differentiated accurately using Scheimpflug metrics. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Keratometric Study of Cornea in Allergic Conjunctivitis Patients

Background: To explore corneal biomechanical changes, identify related factors and determine early indicators of keratoconus (KC) development risk in allergic conjunctivitis (AC) patients. Methods: A total of 50 patients, including 20 eyes without AC and 30 eyes with AC were enrolled in this study. All patients underwent a complete ocular examination, including evaluations of clinical manifestations of AC, corneal tomography and densitometry by Pentacam, corneal biomechanics by Corvis ST, and corneal and epithelial thickness mapping by RTvue optical coherence tomography (OCT). Results: The index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), index of height decentration (IHD) and Belin/Ambrosio enhanced ectasia total deviation index (BAD-D) were significantly higher in the AC group than in the non-allergic conjunctivitis (NAC) group (P &lt; 0.05). The tomography and biomechanical index (TBI) was also significantly higher in the AC group (P =?0.04). The average epithelial thickness in the 2–7?mm annulus was significantly thinner in the AC group than in the NAC group (P &lt; 0.05). The average densitometry of the total cornea and the anterior layer were higher in the AC group than in the NAC group (P &lt; 0.001). The ISV, IVA, KI, IHD and BAD-D were significantly correlated with the TBI and changes in corneal epithelial thickness in AC patients (P &lt; 0.05). The changes in epithelial thickness were closely related to the eye rubbing frequency and allergic sign scores (P &lt; 0.05). CONCLUSIONS: AC patients should be advised to routinely undergo corneal tomographic and biochemical measurements and the TBI could be used an indicator of KC devolopment risk in AC patients.

Anterior segment indices in mentally retarded children

To compare the anterior segment indices between mentally retarded and normal children. The current study was conducted as a cohort. In this study, 73 mentally retarded and 76 normal children were selected from normal school and special schools for mentally retarded children using random cluster sampling method. Mental retardation in children was confirmed by a psychologist. Optometry examinations including visual acuity and refraction were performed for all participants, and ultimately, corneal imaging measurements were taken by Pentacam. The mean age of mentally retarded and normal children was of 13.30 ± 1.83 and 13.05 ± 1.82 years, respectively (P = 0.180). A multiple generalized estimating equations model demonstrated that there is a significant association between central corneal thickness (CCT) (coef = 1.011, P < 0.001), corneal diameter (CD) (coef = 0.444, P = 0.046), anterior chamber depth (ACD) (coef = 0.23), P < 0.001) and index of vertical asymmetry (IVA) (coef = 0.12, P < 0.001) and mental retardation. Cerebral palsy children had higher keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry(IHA), and index of height decentration (IHD) compared to those without cerebral palsy (P < 0.05). Children with moderate mental retardation had higher index of surface variance (ISV), IVA, IHA, and IHD than those with mild mental retardation (P < 0.05). The mean and standard deviation of CCT, CD, ACD and IVA index in mentally retarded children were 535.3 ± 46.68 micron, 11.87 ± 0.42 mm, 3.29 ± 0.24 mm and 0.25 ± 0.18 mm, respectively. These indices in the normal group were 525.53 ± 47.52 micron, 11.84 ± 0.38 mm, 3.15 ± 0.28 mm and 0.17 ± 0.05 mm, respectively. The findings of this study showed that some anterior segment indices were different in mentally retarded compared to normal children. Moreover, some keratoconus indicators were worse in cerebral palsy children and children with higher grade mental retardation. So, it is important to consider keratoconus screening in these children.

Crosslinking for post-laser-assisted in situ keratomileusis corneal ectasia: Transepithelial flap-on 30 minute and flap-lift 4 minute protocol.

To evaluate the outcomes of transepithelial corneal collagen crosslinking (CXL) for management of corneal ectasia after laser-assisted in situ keratomileusis (LASIK). CXL was performed on 18 eyes of 16 patients either with LASIK flap lift (n = 9; 365 nm, 30 mW/cm2, 4 minutes, pulse) or with transepithelial flap-on (n = 9 eyes; 365 nm, 3 mW/cm2, 30 minutes) technique. Postoperative change in maximum keratometry (Kmax), anterior elevation, posterior elevation, spherical equivalent (SE), logMAR uncorrected distance visual acuity (UDVA), aberrations, and central corneal thickness (CCT) were evaluated at 12 months postoperatively. A total of 18 eyes of 16 patients (11 males, 5 females) were included. Overall, Kmax flattened more after flap-on CXL (P = 0.014) compared to flap-lift CXL. The endothelial cell density and posterior elevation were stable throughout the follow-up period. Index of vertical asymmetry (IVA), keratoconus index (KI), and central keratoconus index (CKI) decreased after flap-on CXL at 12 months, postoperatively (P < 0.05), whereas there were no statistically significant changes in these parameters after flap-off CXL group. The spherical aberrations and total root mean square decreased after flap-lift CXL at 12 months, postoperatively (P < 0.05). In our study, transepithelial collagen crosslinking was successfully used to halt disease progression in post-LASIK keratectasia. We recommend flap-on surgical technique for these cases.

Corneal topometric indices and proclivity toward corneal ectasia in vernal keratoconjunctivitis

To investigate changes in topometric corneal indices and proclivity toward corneal ectasia, as well as keratometric indices and anterior chamber dimensions in palpebral vernal keratoconjunctivitis (VKC). This study included 80 patients with clinically established symptoms of grade 0 or grade 1 palpebral VKC (group 1) and 66 healthy participants (group 2). After a comprehensive ophthalmic examination including best-corrected visual acuity, intraocular pressure measurements and slit-lamp biomicroscopy, pachymetric indices and anterior chamber dimensions were measured using the Pentacam HR rotating Scheimpflug device. Topometric indices, which are particularly useful for determining proclivity toward corneal ectasia, were extracted from a topometric map. In groups 1 and 2, the mean ages were 13.11±5.22 and 16.45±5.09 years, respectively. The mean age at disease onset in group 1 was 10.09±5.03 years, and the mean disease duration was 36.23±8.43 months. Group 1 had significantly higher mean topometric indices than group 2, particularly the index of surface variance (P=0.001), index of vertical asymmetry (P=0.007), center keratoconus index (P=0.050), and Belin/Ambrosio enhanced ectasia total deviation value (P=0.032). Mean posterior corneal astigmatism differed significantly between groups 1 and 2 (P=0.003). Significantly higher mean topometric indices in VKC indicate a proclivity for corneal ectasia, which could be attributed to general changes in the corneal ultrastructure caused by persistent itching-induced eye rubbing.

Alteration in corneal topography asymmetry indices following corneal refractive surgery

Purpose We aimed to follow up corneal refractive asymmetry index changes following refractive surgery for cornea after correction of low-grade myopia and to determine which technique causes marked affection of the indices. Patients and methods This prospective study conducted from October 2020 to December 2021 included two groups of patients, the photorefractive keratectomy (PRK) group and the laser in-situ keratomileusis (LASIK) group. Every patient in each group had to follow a schedule of visits after surgery for the next day, 1 week, 1 month, and after 3 months. Patients who failed to follow this schedule were excluded from the study. Results The PRK group contained 42 eyes with a mean uncorrected visual acuity that improved significantly, corneal power (K-reading) and pupil center thickness reduced significantly. Surface variance index, central keratoconus index, and height decentration index did not change significantly. Vertical asymmetry index and minimum radius of curvature (Rmin) increased significantly while height asymmetry index decreased significantly. Our LASIK group contained 40 eyes that underwent changes similar to those in the PRK group regarding uncorrected visual acuity, the K-reading, and the pupil center thickness. The surface variance index, vertical asymmetry index, and height asymmetry index, height decentration index and Rmin increased significantly while the central keratoconus index decreased significantly. The keratoconus index reduced significantly in both groups. Conclusion The PRK is a more conservative technique than the LASIK technique regarding the affection of corneal asymmetry indices.

Could Corneal Densitometry be a Progression Criterion for Subclinical Keratoconus?

The objective of this study is to investigate the changes in topometry, tomography, and corneal densitometry in subclinical keratoconus (SK) at the 6-month interval. The clinical keratoconus and SK groups included 25 eyes; the control group included 22 eyes from 22 patients. Corneal topographic, tomographic, topometric, and densitometric values obtained using the Pentacam HR imaging system were analyzed. Posterior elevation (PE), Keratoconus index (KI), index of height asymmetry (IHA), index of height decentration (IHD), Dp, Da, Final D, maximum pachymetric progression index (PPImax), and maximum Ambrósio relational thickness parameters showed significant changes between the baseline and the 6th-month follow-up in SK group (p<0.05 for all values). There were significant changes in all zones except a central layer of 6-10 zone, anterior, and central layer of 10-12 zone between the baseline and the 6th-month follow-up in the SK group (p<0.05, for all values). The changes in mean±standard deviation of KI, IHA, IHD, PPImax parameters, and corneal densitometry values of the posterior layer of 0-2 mm and 2-6 mm zones were significant in the SK group compared to the controls (p<0.05, for all values). PE, KI, IHA, IHD, and PPImax parameters as well as increasing corneal light backscatter of the posterior central layer might be useful for follow-up of progression of SK. New multimeric parameters created by combinations of topometric, tomographic, and corneal densitometry parameters could be the future of SK follow-up.

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

The Changing Face of the Cornea in a Case of Juvenile Glaucoma and Subclinical Keratoconus.

We report on a 23-year-old man who presented with bilateral subclinical keratoconus and juvenile glaucoma (JG). With intraocular pressures (IOPs) of 30 and 28 mmHg, both eyes were consecutively operated by adjusted trabeculotomy, leading to a remarkable decrease in IOP to well below the mean for this surgery in JG. Meanwhile, most keratoconus indices clearly progressed in the first 5 months postoperatively, with increases in corneal hysteresis, associated with a remarkable drop in the corneal resistance factor. During the following years, IOP remained low, and all changes (except the increase in corneal hysteresis) reverted to near preoperative levels through the follow-up course of 5 years. This report complements a few existing reports that show the coincidence of keratoconus and JG, and, more importantly, documents a novel pattern of remarkable and prolonged corneal changes following surgical lowering of IOP in eyes with these changes. Postoperative biomechanical disturbances in the cornea and possibly limbus are proposed in cases of JG and subclinical keratoconus.

Heritability of Corneal Parameters in Nuclear Families With Keratoconus

PurposeThis study aimed to investigate the heritability of corneal parameters obtained by Pentacam in nuclear families with keratoconus (KC).MethodsA total of 82 patients with KC and their biological parents (n = 164) were recruited in the current study. All subjects underwent corneal tomography with Pentacam. Family units were analyzed to calculate the heritability of corneal parameters by linear mixed effects model using the R statistical software.ResultsThe pachymetry at apex, pupil, and thinnest point were all significantly heritable at 43.26%, 42.63%, and 43.09%, respectively. The heritability of flat meridian keratometry, steep meridian keratometry, and mean keratometry in the anterior surface were 10.36%, 9.05%, and 10.21%, respectively, and that of flat meridian keratometry, steep meridian keratometry, and mean keratometry in the posterior surface were 8.44%, 9.67%, and 9.06%, respectively. The posterior radius of curvature had higher heritability in comparison with anterior radius of curvature (19.16% vs. 14.37%). Moreover, among combined topometric indices, the heritability of index of vertical asymmetry was the highest (19.49%), and that of central keratoconus index was the lowest (6.64%).ConclusionsThe present study demonstrated a substantial heritability of corneal parameters in nuclear families with KC. The pachymetric indices are heritable and may be suitable as KC endophenotypes, suggesting a necessity to discover the genes associated with corneal thickness in KC.Translational RelevanceThe pachymetric indices are heritable and may be suitable as KC endophenotypes, indicating that the pachymetric indices might be a corneal characteristic to predict the occurrence of KC.