Posterior Elevation Research Articles

Repeatability of Scheimpflug Tomography for Assessing Fuchs Endothelial Corneal Dystrophy

To determine if agreement between subjective interpretations of Scheimpflug tomography maps of corneas with Fuchs endothelial corneal dystrophy (FECD) is affected by daily and hourly changes in corneal edema. Reliability analysis. Scheimpflug imaging pachymetry and posterior elevation maps of corneas with a range of severity of FECD were evaluated in a randomized manner for the presence of 3 tomographic features of edema. Agreement between interpretations of 1 masked observer was assessed (percentage, and κ-statistic with 95% confidence interval) for images taken within minutes on the same day, for images taken at a similar time on a different day, and for images taken over the course of a morning. Intra- and interobserver agreement was also assessed. Interpretations for individual tomographic features agreed for ≥88% of images (κ ≥ 0.75) taken within minutes on the same day; complete disagreement (ie, disagreement for all 3 tomographic features in an image) occurred in ≤3% of images. Interpretations agreed for ≥77% of images (κ ≥ 0.52) taken at a similar time on a different day; complete disagreement did not occur. Interpretations agreed for ≥81% of images (κ ≥ 0.61) taken over the course of a morning; complete disagreement occurred in ≤6% of images. Intraobserver agreement was ≥93% (κ ≥ 0.83) and interobserver agreement was ≥93% (κ ≥ 0.66); complete disagreement did not occur. Subjective interpretation of Scheimpflug images in FECD is highly repeatable for disease classification. Although small variations in interpretations resulted from pathophysiologic changes in corneal hydration and other factors, clinically significant disagreements in interpretation were uncommon and therefore unlikely to affect clinical decision-making.

Three-year follow-up of accelerated transepithelial corneal cross-linking for progressive paediatric keratoconus

PurposeTo investigate the long-term safety and efficacy of accelerated transepithelial cornealcross-linking (ATE-CXL) in children with progressive keratoconus.MethodsFifty-three eyes of 41 paediatric patients (34 boys, 7 girls; mean age 14.81±1.96 years)...

Influence factors and differences of posterior corneal elevation measured by Pentacam system combined with Corvis ST

Objective: To investigate the influence factors and differences of abnormal posterior corneal elevation by Pentacam system and Corvis ST. Methods: This retrospective case series study included 227 eyes of 144 patients (90 males, 139 eyes; 54 females, 88 eyes) from December 2017 to October 2018 who were going to receive corneal refractive surgery at the Corneal Refraction Department of Qingdao Eye Hospital. The general data of the patients including gender, age, refractive parameters, optimal correction of spherical and cylindrical diopters were collected. All patients underwent Pentacam system and Corvis ST measurement. According to the back difference (BD) of Pentacam parameters, BD<12 μm was set as the control group (59 patients, 118 eyes) and BD≥12 μm as the high BD group (85 patients, 109 eyes). In the high BD group, BD≤16 μm was set as the suspicious group (44 patients, 53 eyes), while BD>16 μm was set as the abnormal group (41 patients, 56 eyes). Seven parameters of Pentacam and 15 parameters of Corvis ST were selected. The Pentacam parameters included BD, anterior surface keratometry (ASK), posterior surface keratometry (PSK), anterior surface astigmatism (AAstig), posterior surface astigmatism (PAstig), central corneal thickness (CCT), and corneal diameter (W-W). The parameters of Corvis ST included the first applanation time (AT(1)), the first applanation length (AL(1)), the first applanation velocity (AV(1)), the second applanation time (AT(2)), the second applanation length (AL(2)), the second applanation velocity (AV(2)), highest concavity time (HCT), highest concavity peak distance (HC-PD), highest concavity deformation amplitude (HC-DA), highest concavity radius (HC-R), the ratio of deformation amplitude (DA ratio), Integr. Radius, corneal thickness thinnest/pachymetric progression (ARTh), SPA1 (resultant pressure divided by deflection amplitude at the first applanation), and the Corvis Biomechanical Index (CBI). The comparison between the groups was analyzed with Independent sample t test, Kruskal-Wallis H test, and Bonferroni test. Spearman rank correlation analysis was used to explore the correlation factors of BD, and the main factors affecting BD were found through multiple linear regression. Results: There were no statistically significant differences between the control group and the high BD group in age, spherical diopters, and cylindrical diopters (t=-3.311, -1.808, -2.359; P=0.071, 0.072, 0.121, respectively). In Pentacam parameters, ASK, PSK, PAstig, and W-W showed significant differences among groups (Z=18.492, 31.547, 10.773, 70.167; P<0.05). AAstig and CCT showed no statistical difference between groups (P>0.05). Compared with the control group [42.80 (41.98, 44.00)], ASK increased in the abnormal group [43.40 (42.20, 44.40)] significantly (t=-4.292; P<0.05). PSK of the suspicious group [-6.50 (-6.60, -6.35)] and the abnormal group [-6.50 (-6.70, -6.33)] increased significantly compared with the control group [-6.30 (-6.50, -6.20)] (t=4.492, 4.618; P<0.05). Compared with the control group [0.40 (0.30, 0.50)], PAstig of the suspicious group [0.40 (0.30, 0.40)] and the abnormal group [0.40 (0.30, 0.40)] increased significantly (t=2.796, 2.515; P=0.016, 0.036). Compared with the control group [11.50 (11.40, 11.80)], W-W of the suspicious group [11.40 (11.00, 11.60)] and the abnormal group [11.10 (10.90, 11.30)] decreased, and W-W of the abnormal group also decreased significantly compared with the suspicious group (t=3.235, 8.353, 4.282; P<0.05). The correlation analysis between BD and Pentacam parameters of patients in each group showed that BD was negatively correlated with W-W (r=-0.614, -0.304, -0.396, -0.661, P<0.05) in the control group, the suspicious group, the abnormal group, and all patients, while BD had a low correlation with other parameters or no significant correlation. The correlation analysis of BD and Corvis ST parameters in patients showed that only in the suspicious group, BD was positively correlated with AV(1), HCT, and HC-DA (r=0.332, 0.361, 0.382, P<0.05), while no significant correlation was found between BD and other Corvis ST parameters in each group. In order to further explore the main factors affecting BD, Pentacam parameters and Corvis ST parameters were selected as independent variables with BD as the dependent variable to establish a multivariate linear regression analysis model. There was no collinearity between variables W-W, ASK, PSK, HC-PD, SPA1, and CCT (tolerance<0.100). The equation test result was F=37.221, P<0.001, adjusted r(2)=0.504, and the fitting was good. Conclusions: Among the Pentacam parameters, W-W, ASK, and PSK are the main factors affecting the change of BD. HC-PD and SPA1 in the Corvis ST parameters may also have some influence on BD. The Pentacam system combined with Corvis ST is a very useful differential diagnosis system for patients with abnormal BD. (Chin J Ophthalmol, 2020, 56:110-117).

Corneal elevation indices and pachymetry values of Saudi myopes using scheimpflug imaging.

Objectives:To report the corneal elevation and thickness values for Saudi myopes and to evaluate the differences between these parameters in subgroups of this target population.Methods:Pentacam corneal topographic maps of the right eyes of patients visiting Al-Hokama Eye Clinic, Riyadh, Saudi Arabia, a tertiary eye center between January 2009 and December 2015 were retrospectively analyzed in this cross-sectional study. The patients were grouped into 3 categories based on their spherical readings: mild (-0.25 to -2.75D), moderate (-3.00 to -5.75D), and severe (≥-6.00D). Furthermore, patients with cylindrical readings of ≥-1.00 diopter were categorized as having myopic astigmatism, whereas those with less than -1.00 cylindrical diopter were categorized as having simple myopia.Results:Our sample was comprised of 1,276 patients; 838 (65.7%) had simple myopia and 438 (34.3%) had myopic astigmatism. The values for the whole myopic group were as follows: anterior corneal elevation (AE) at the apex= 2.60±1.48 (standard deviation), thinnest AE= 2.56±1.68, posterior elevation (PE) at the apex= 3.67±3.58, thinnest PE= 4.92±3.81, central pachymetry= 550.09±34.29, apical pachymetry=550.73±34.64, and thinnest pachymetry= 546.30±34.61. All of the measurements, except the apical PE and thinnest PE, were statistically significant across the simple and myopic astigmatism groups (p<0.05). Comparing the mild to moderate myopia groups revealed a significant difference in the apical AE (p=0.037). Moreover, the comparison between the mild and severe myopia groups revealed that the apical PE and the thinnest PE, as well as the central, apical, and thinnest pachymetry values were statistically significantly different (p<0.05).Conclusion:The corneal elevation indices and thicknesses specific to the Saudi myopes were found to be comparable to the international databases in terms of the elevation and thickness in some of the parameters.

Higher-order aberrations in keratoconus suspect

Purpose: The aim of this study was to assess the pattern of higher-order aberrations (HOAs) in keratoconus suspect (KCS) eyes using Scheimpflug–Placido topography (Sirius, CSO, Italy) and also to detect the sensitivity and specificity of all parameters to discriminate subclinical keratoconus (KC), and normal eye was investigated. Patients and Methods: This was a retrospective, cross-sectional study of 100 eyes of KCS patients along with 50 normal eyes as a control group. The following parameters were evaluated: sphere, cylinder, spherical equivalent, flat and steep keratometry (K), mean K, total root mean square (RMS), RMS coma, RMS spherical aberration, and anterior and posterior corneal elevation in the most curved part of the cornea. All eyes underwent Sirius Scheimpflug–Placido topography evaluation. Results: The KCS group showed significantly higher values for cylinder, mean flat, steep, and mean keratometry (K) compared to the control group. There were statistically significant differences in all aberrometric parameters in KCS compared with the control group except for spherical aberration. The optimum cutoff point and area under receiver operating characteristic curve of both RMS and elevation (anterior and posterior) achieved larger than 90% in both sensitivity and specificity. Conclusion: HOAs and corneal elevation (anterior and posterior) of the most curved part of the cornea proved to be able to distinguish KCS from the normal control group. Higher amounts of vertical coma and larger values of coma-like RMS have been found in patients with suspect KC when compared to normal corneas.

Advanced keratoconus with very low pachymetry – Can contact lens avoid corneal surgery?

Clinical relevance: Keratoconic eyes with low pachymetric values, precluding safe CXL can show significant improvement in vision with newer scleral Contact lenses(CL), which was not possible with older rigid CLs. Purpose: To describe diagnostic and management difficulties in keratoconic eyes with pachymetry too low for CXL (Collagen Cross linking)necessitating surgery for improving tensile strength, yet having significant improvement in vision with newer rigid contact lenses such that immediate keratoplasty can be deferred. Methods: Case records of 16 patients (20 eyes) were reviewed. All patients had advanced keratoconus with low pachymetric values but had significant improvement in vision with rigid CLs. CXL was not safely feasible in these eyes and immediate surgical treatment for tissue strengthening was deferred as they had good vision with newer rigid CLs. Patients were kept under close observation due to the risk of developing corneal hydrops. Results: Mean age was 25.68 years. Mean best-corrected visual acuity with glasses was 0.54logMAR, whereas, with rigid CLs was 0.18logMAR. Mean steep-keratometry (K) was 62.66D. Mean central pachymetry, highest posterior surface elevation, and pachymetry at thinnest location was 314.4, 119.6 and 313.61microns respectively. Mean follow-up was 4 years. Conclusion: Advanced keratoconic eyes may have pachymetric values too low for CXL, therefore needing keratoplasty for tissue strengthening and yet can have good vision with rigid CLs. Quantitative analysis of further progression of keratoconus in these eyes is difficult as imaging techniques become unreliable in advanced stages of the disease. Significant improvement in vision with newer rigid and scleral CLs makes the decision to operate, purely for tissue building, difficult.

Assessment of posterior urethra in benign prostatic hyperplasia and after its surgery.

Introduction:Surgical management of benign prostatic hyperplasia (BPH) primarily consists of transurethral resection of the prostate (TURP). Due to BPH and after surgical intervention, anatomic variations in the posterior urethra are expected. Due to the paucity of information regarding posterior urethral anatomic variations in these conditions and its aftermath, this study was undertaken to evaluate the anatomic variations in the posterior urethra after TURP.Materials and Methods:This prospective observational study was conducted over 2 years at the Department of Surgery and Radiodiagnosis, University College of Medical Sciences, Delhi. All consenting patients undergoing TURP for BPH were included in the study. We assessed the posterior urethral changes in BPH before and 3 months after the procedure. Diagnostic modalities used were urethrocystoscopy, micturating cystourethrogram, and retrograde urethrogram. Furthermore, the prostate volume and postvoid residual volume of urine were compared before and after its surgery using ultrasonography. Urodynamic studies were used to calculate total voided volume (TVV), peak flow rate (PFR), voiding time (VT), and hesitancy.Results:Mean age of the patients was 68.12 ± 7.83 years. Lengthening in posterior urethra was seen in BPH patients with a mean of 4.24 ± 1.012 cm. Postprocedure, there was a mean reduction of 2.6 ± 1.225 cm in length of the posterior urethra (P < 0.0001). Prostatic urethral angle was increased in patients suffering from BPH, and it decreased after undergoing surgical management (P < 0.679). All patients enrolled in our study had prostatic lobes enlargement, and after surgery, this enlargement was reduced in most of the patients with 21 having no prostatic enlargement, and in four patients, bilateral lateral lobe was not completely reduced (P = 1.000). Stricture in prostatic urethra was observed in 2 out of 25 (8%) patients operated for BPH. Evaluation of various parameters of urodynamic studies revealed the net improvement in the TVV of 157.746 ± 120.999 ml, as before the procedure, this value was 176.715 ± 72.272 ml, and after surgery, it was 334.46 ± 78.588 ml (P < 0.001). VT taken by patients before surgery was 57.377 ± 16.858 s, and postprocedure, this value was 33.31 ± 8.807 s. This net reduction of 24.069 ± 14.88 s was statistically significant (P < 0.0001). PFR before the procedure was 6.177 ± 3.5067, and postprocedure, this value was 26.43 ± 7.112 ml/s with a net improvement of 20.253 ± 9.226 ml/s (P < 0.0001). Hesitancy in BPH patients before the procedure was 23.908 ± 15.521 s. Postprocedure, hesitancy decreased to a value of 6.79 ± 4.435 s with a net reduction of mean 17.115 ± 15.817 s (P < 0.002).Conclusion:By our findings, we conclude that BPH is associated with anatomic variations in posterior urethra such as lengthening of the length of the posterior urethra and increased posterior urethral elevation, which is measured by an increase in posterior urethral angle (PUA). Whereas post-TURP, there is a shortening of posterior urethra, decrease in PUA, decrease in prostatic volume, postvoid residual urine volume, and improvement in uroflowmetric parameters.

Ectasia after keratorefractive surgery: Analysis of risk factors and treatment outcomes in the Indian population.

Purpose:To analyze the risk factors in eyes developing ectasia following keratorefractive procedures. In addition, the study assessed visual outcomes following various treatment modalities for ectasia.Methods:In this retrospective study, data of patients who underwent keratorefractive procedures, presenting to the refractive services of a tertiary eye care hospital in South India between January 2016 and May 2019 was analyzed. Of these, the eyes that developed ectasia were noted and the possible risk factors were determined. Visual outcomes following treatment with corneal collagen crosslinking (CXL) with or without intracorneal ring segment implantation (ICRS) or topography-guided corneal ablation (T-PRK) were analyzed.Results:Forty eyes of 26 patients developed ectasia following keratorefractive procedures, with a mean interval of 73.1± 45.4 months between primary procedure and ectasia development. Of these, 14 patients had bilateral presentation. Identifiable risk factors included ablation depth >75 μm (59.25%), percentage of tissue altered (PTA) >40% (48.14%), residual stromal bed <300 μm (22.22%), mean refractive spherical equivalent >8 D (25.92%), inferior–superior (I–S) asymmetry >1.4D (7.40%), central corneal thickness (CCT) <500 μm (7.40%), Belin Ambrosio Display (BAD) >2.5 (7.40%), posterior float elevation maximum ≥18 μm (3.70%), and pellucid marginal degeneration (PMD; 3.70%).Conclusion:Our study shows that only 70% of the eyes demonstrated an identifiable risk factor for the development of ectasia. Ablation depth of >75 μm and the PTA >40% were the most common risk factors. Treatment following CXL with ICRS or T-PRK demonstrated significantly better visual outcomes in comparison with CXL alone.

Joint line elevation is not associated with mid-flexion laxity in patients with varus osteoarthritis after total knee arthroplasty.

Previous cadaver studies showed that the additional bone cuts in the distal and posterior femur and joint line elevation resulted in laxity at mid-flexion after total knee arthroplasty (TKA). However, these results are not always applicable to TKA candidates because the related studies used cadaver knees with no osteoarthritis. It was hypothesized that the joint line elevation results in mid-flexion laxity after TKA in patients with knee osteoarthritis. The purpose of this study was to analyze the relationship between joint line elevation and mid-flexion laxity in patients with knee osteoarthritis. 30 knees with varus osteoarthritis undergoing TKA were evaluated. Two femoral trial component models were prepared: (1) normal model with a thickness of the distal and posterior femoral components of 9mm, and (2) 2-mm joint line elevation model with a thickness of the distal and posterior femoral components of 9 - 2 = 7mm. This 2-mm joint line elevation model simulated an additional bone cut in the distal and posterior femur, and joint line elevation, without an additional bone cut. The femoral trial component models were set before implantation and measured the joint gap kinematics using a tensor device through the full knee range of motion. The differences in joint gap change from 30° to 90° were not statistically significant between the two models. However, the joint line elevation model decreased the joint gap laxity at 120° (p = 0.02) and at 145° (p = 0.01). This study showed that a 2-mm joint line elevation was not associated with mid-flexion laxity in patients with varus osteoarthritis in the knee. The results of this study differed from the results in previous cadaver studies. Therapeutic study, level II, prospective comparative study.

Comparison of anterior segment changes after femtosecond laser LASIK and SMILE using a dual rotating Scheimpflug analyzer

BackgroundTo compare the changes in the anterior segment after femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) using a dual rotating Scheimpflug (DRS) analyzer (Galilei®; Ziemer Ophthalmology, Port, Switzerland).MethodsA total of 218 eyes of 109 patients who underwent FS-LASIK or SMILE for myopic correction were retrospectively studied. Ninety-eight eyes of 49 patients who underwent FS-LASIK were compared to 120 eyes of 60 patients treated with SMILE. A DRS analyzer was used for preoperative and 6-month postoperative anterior segment analyses. Measured variables included the central corneal thickness (CCT), anterior chamber depth (ACD), anterior and posterior keratometry (K), anterior and posterior best-fit sphere radius, and maximum posterior elevation (MPE).ResultsAfter the procedure, the amount of CCT decrease was higher in the SMILE group than in the FS-LASIK group, but it was not statistically significant. The MPE was significantly increased after both procedures (p < 0.001 and p = 0.001 in the FS-LASIK and SMILE groups, respectively), with the amount of elevation being higher after FS-LASIK than after SMILE even though it was not statistically significant. And there was a significant change in the steep and average posterior K in the FS-LASIK group (p = 0.006 and 0.001, respectively), but not in the SMILE group.ConclusionsRegarding changes in the MPE and posterior K, changes in the posterior corneal surface were greater after FS-LASIK than after SMILE.Trial registrationThe trial registration number: KCT0003628. Date of registration: 15 March 2019.

Analysis of anterior chamber morphological changes after small incision lenticule extraction

Objective To investigate the changes of anterior chamber profiles after small incision lenticule extraction(SMILE) and analyze the possible influencing factors. Methods A case observation study was designed.Thirty-one patients(59 eyes) with myopia and myopic astigmatism who underwent SMILE surgery at the Refractive Surgery Center of Tianjin Eye Hospital from April to December 2015 were enrolled and examined preoperatively and at 1 month, 3 and 6 months postoperatively.The anterior chamber profiles, including anterior chamber depth (ACD), anterior chamber volume (ACV) and anterior chamber angle (ACA) were measured using the Pentacam.The correlations between parameters were analyzed and the differences of the parameters at different time points were compared.This study followed the Declaration of Helsinki.This study protocol was approved by Ethic Committee of Tianjin Eye Hospital (No.TJYYLL-2015-20). Written informed consent was obtained from each subject before the operation. Results Compared with pre-operation, the central corneal thickness (CCT) was significantly decreased at 1 month, 3 and 6 months postoperatively (all at P 0.05). The posterior corneal elevation (PCE) at different time points before and after surgery was significantly different (F=19.249, P<0.001), compared with the preoperation, the PCE at 1 month, 3 and 6 months postoperatively moved slightly backward (all at P<0.05). The preoperative ACD was (3.33±0.25)mm, the preoperative ACV was (217.46±31.55)mm3, and the ACD was (3.31±0.25), (3.30±0.25) and (3.30±0.25)mm, the ACV was (214.71±33.09), (211.14±33.65) and (210.08±32.19)mm3, respectively at 1 month, 3 and 6 months postoperatively, with significant differences at different time points before and after surgery (F=12.477, 12.205; both at P<0.001), compared with the preoperation, the ACD at 1 month, 3 and 6 months postoperatively and ACV at 3 months and 6 months postoperatively were obviously decreased, with a significant difference between them (all at P<0.05). There was a significant positive correlation between ACD and ACV at different time points before and after surgery (r=0.870, 0.893, 0.886, 0.884; all at P<0.001). The preoperative ACD was negatively correlated with CCT (r=-0.286, P<0.05). Conclusions The ACD is decreased postoperatively, it is basically stable at (3.30±0.25)mm, which satisfies the requirements of the ACD required for implantable collamer lens.And the stable state of ACD is also important for keratoconus detection. Key words: Small incision lenticule extraction; Anterior chamber depth; Anterior chamber volume; Anterior chamber angle

The Coupled Kinematics of Scapulothoracic Upward Rotation.

Scapulothoracic upward rotation (UR) is an important shoulder complex motion allowing for a larger functional work space and improved glenohumeral muscle function. However, the kinematic mechanisms producing scapulothoracic UR remain unclear, limiting the understanding of normal and abnormal shoulder movements. The objective of this study was to identify the coupling relationships through which sternoclavicular and acromioclavicular joint motions contribute to scapulothoracic UR. This was a cross-sectional observational study. Sixty participants were enrolled in this study; 30 had current shoulder pain, and 30 had no history of shoulder symptoms. Shoulder complex kinematics were quantified using single-plane fluoroscopy and 2D/3D shape matching and were described as finite helical displacements for 30-degree phases of humerothoracic elevation (30 degrees-60 degrees, 60 degrees-90 degrees, and 90 degrees-120 degrees). A coupling function was derived to estimate scapulothoracic UR from its component motions of acromioclavicular UR, sternoclavicular posterior rotation, and sternoclavicular elevation as a function of acromioclavicular internal rotation. The proportional contributions of each of the component motions were also calculated and compared between phases of humerothoracic elevation and groups. Scapulothoracic UR displacement could be effectively predicted using the derived coupling function. During the 30- to 60-degree humerothoracic elevation phase, acromioclavicular UR accounted for 84.2% of scapulothoracic UR, whereas sternoclavicular posterior rotation and elevation each accounted for < 10%. During later phases, acromioclavicular UR and sternoclavicular posterior rotation each accounted for 32% to 42%, whereas sternoclavicular elevation accounted for < 11%. Error due to the tracking of sternoclavicular posterior rotation may have resulted in an underprediction of its proportional contribution and an overprediction of the proportional contribution of acromioclavicular UR. Acromioclavicular UR and sternoclavicular posterior rotation are the predominant component motions of scapulothoracic UR. More research is needed to investigate how these coupling relationships are affected by muscle function and influenced by scapular dyskinesis.

Corneal elevation changes after forced eyelid closure in healthy participants and in patients with keratoconus

BackgroundTo assess pointwise corneal elevation changes after forced eyelid closure test (FECT) in the eyes of healthy subjects and in eyes with keratoconus.MethodsTwenty‐nine subjects with keratoconus and 31 healthy volunteers were evaluated. Patients with keratoconus who had corneal hydrops, apical scarring, corneal thickness ≤ 400 μm, ocular surface disease, contact lens wear on the examination day and a history of corneal cross‐linking were excluded. Exclusion criteria for healthy participants were spherical error > +3.00 D and < −3.00 D, corneal astigmatism > 1.50 D, corneal curvature > 47 D, ocular allergy, clinical findings and family history of keratoconus. Pentacam was performed before and after 20-seconds of FECT and raw data were extracted from the built‐in software. Pointwise anterior and posterior elevation changes in the central 8-mm cornea were assessed using paired samples t‐test and heat maps were constructed to reflect mean changes and statistically significant data points. Statistical significance was assumed at p < 0.01.ResultsAge and gender were similar between healthy subjects (24.5 ± 1.6-years, 46.4 per cent female) and subjects with keratoconus (28.6 ± 9.2-years, 46.4 per cent female, p = 0.19, 0.61, respectively). Healthy eyes displayed posterior depression clustering in the inferotemporal and inferonasal areas (mean change: −4.5 ± 7.8 μm and −5.2 ± 9.8 μm, respectively, all p < 0.01). In contrast, keratoconus eyes exhibited a wider area of posterior elevation clustering in the inferior cornea (mean change: 8.1 ± 14.5 μm, all p < 0.01) with a small extension in the inferotemporal cornea (mean change: 12.1 ± 22.3 μm, all p < 0.01).ConclusionFECT elicits corneal elevation changes mainly in the inferior cornea with the change being more pronounced and wider in eyes with keratoconus.

Predicting the Prognosis of Fuchs Endothelial Corneal Dystrophy by Using Scheimpflug Tomography

To determine if Scheimpflug tomography pachymetry map and posterior elevation map patterns, central corneal thickness (CCT), and corneal backscatter can predict the prognosis of Fuchs endothelial corneal dystrophy (FECD). Cross-sectional study with follow-up of outcomes. Ninety-six eyes (56 subjects) with a range of severity of FECD. Corneas were graded by cornea specialists according to the area and confluence of guttae and the presence of clinically definite edema. Masked and randomized Scheimpflug imaging pachymetry map and posterior elevation map patterns were assessed by 1 observer for loss of regular isopachs, displacement of the thinnest point of the cornea, and the presence of posterior surface depression. The prognosis of eyes over a 5-year (median) follow-up period was determined based on FECD progression (new onset of clinically definite edema or ≥5% increase in CCT) or intervention by endothelial keratoplasty. Cumulative probabilities of progression and intervention were estimated from survival analyses, with risk factors determined by using Cox proportional hazards models. Pachymetry map and posterior elevation map patterns, corneal backscatter, and CCT (ultrasonic pachymetry). In univariate analyses, loss of regular isopachs (hazard ratio [HR], 18.00) displacement of the thinnest point (HR, 11.53), focal posterior surface depression (HR, 10.21), and anterior corneal backscatter (HR, 1.22, per 1-grayscale unit increment), were risk factors for progression or intervention (P < 0.001), whereas CCT (HR, 1.30, per 25-μm increment) was not (P = 0.15). In multivariate analyses, loss of regular isopachs (HR, 11.57; P < 0.001) and displacement of the thinnest point (HR, 5.61; P= 0.02) were independent and clinically important risk factors for progression and intervention. The 5-year cumulative risk of disease progression and intervention was 7%, 48%, and 89% when none, 1 or 2, and all 3 pachymetry map and posterior elevation map parameters were present, respectively (P <0.001). The 4-year cumulative risk of disease progression and intervention after uncomplicated cataract surgery was 0%, 50%, and 75% when none, 1 or 2, and all 3 pachymetry map and posterior elevation map parameters were present, respectively (P < 0.001). Three Scheimpflug tomography pachymetry map and posterior elevation map patterns can predict FECD prognosis independent of CCT. The risk of FECD progression and intervention, including after uncomplicated cataract surgery, increases according to the number of parameters present.

Keratoconus Screening Among Myopic Children.

AimTo assess the topographic corneal changes and the incidence of keratoconus among children with high myopia.SettingsIt is a prospective study, in which 174 eyes of children with high myopia were studied in the period between August 2015 and June 2018.MethodsAll patients were examined to assess the refractive error and corneal examination using Scheimpflug camera to evaluate different corneal parameters.ResultsStudied children aged between 6 and 14 years (11.05±1.98). Males represented 54% of the cases (n=94). The mean spherical error was −7.75±2.97 ranging from −6 to −13.50D. The mean cylindrical error was −4.12±1.78D (−1 to −8). Regarding corneal examination, data recorded were those about maximum K reading (kmax), thinnest location, highest anterior and posterior elevation in 4mm zone, and higher-order corneal aberrations. Analysis of the obtained data revealed 16 eyes (9.2%) with keratoconus. These eyes were considered as a separate group and compared with the remaining eyes. There was significant difference in kmax (p= 0.03), anterior elevation, and posterior elevation (p=0.01 for both). Regarding myopia or astigmatism, there were no significant differences when compared with normal eyes. But high myopia with low astigmatism were found in five eyes of them (31.2%). The main statistically different aberrations were vertical coma (−2.04±0.99) (p=0.01) and spherical aberrations (−0.9±0.78) (p=0.02). Regarding gender, there were 11 eyes in boys (68.7%), and this was statistically significant (p=0.01). Vernal keratoconjunctivitis with frequent eye rubbing was found in 6 eyes (37.5%).ConclusionChildren with high myopia irrespective of the degree of astigmatism may have corneal abnormalities which are more pronounced in cases with vernal keratoconjunctivitis. Corneal examination should be performed for highly myopic children to detect any corneal abnormality and to treat it as early as possible.

Keratoconus detection using deep learning of colour-coded maps with anterior segment optical coherence tomography: a diagnostic accuracy study

ObjectiveTo evaluate the diagnostic accuracy of keratoconus using deep learning of the colour-coded maps measured with the swept-source anterior segment optical coherence tomography (AS-OCT).DesignA diagnostic accuracy study.SettingA single-centre study.ParticipantsA total...

Correlation of corneal elevations measured by Scheimpflug corneal imaging with severity of keratoconus

PurposeTo evaluate the correlation of corneal elevation and difference elevation with severity of keratoconus. MethodsAnterior and posterior corneal elevations with both conventional and enhanced best-fit spheres (using rotating Scheimpflug camera) were measured. Front and back difference elevation were extrapolated from difference map of Belin/Ambrỏsio Enhanced Ectasia Display of the Scheimpflug system. Data from corneal elevations and difference elevations were correlated with maximum keratometry, minimal corneal thickness, and severity of keratoconus as assessed by Amsler-Krumiech classification of keratoconus. ResultsNinety eyes of 55 keratoconus patients of different clinical stages were evaluated. There was a significant positive correlation between keratoconus severity and corneal elevations (anterior and posterior elevation as measured with both conventional and enhanced best-fit spheres) and also between keratoconus severity and corneal elevation differences (P < 0.001 and r > 0.625 for all). Maximum keratometry (Kmax), mean keratometry (Kmean), and all corneal elevations and difference elevations were highly correlated (P < 0.001 and r > 0.840 for all). A significant negative correlation was found between minimum corneal thickness and all corneal elevations and difference elevations (P < 0.001 and r < 0.711 for all). Receiver operating characteristic (ROC) curve analyses showed that anterior and posterior difference elevations have the best predictive accuracy for grading keratoconus severity. ConclusionEvaluation of corneal elevation and difference elevation data obtained from Scheimpflug corneal imaging is useful for grading severity of keratoconus.

Diagnostic Sensitivity of Different Reference Bodies When Using Scheimpflug Tomography in a Myopic Population with Keratoconus.

Purpose To establish which reference body offers the greatest sensitivity in keratoconus (KC) diagnosis, obtain normative data for the myopic population with toric ellipsoid reference bodies, and determine the cutoff points for a population with KC. Methods A retrospective, observational study of the entire Scheimpflug tomographer database of the Fundación Jiménez Díaz in Madrid was conducted to identify a normal myopic and a KC myopic population. Three different reference bodies were tested on all patients: best fit sphere (BFS), best fit toric ellipsoid with fixed eccentricity (BFTEFE), and best fit toric ellipsoid (BFTE). Anterior and posterior elevation measurements at the apex and thinnest point were recorded, as well as the root mean square of posterior elevations (RMS-P). Normative data were extracted, and receiver operating characteristic (ROC) curves were generated to obtain cutoff points between the normal and KC population. Results A total of 301 eyes were included, comprising 219 normal myopic and 82 myopic KC eyes. BFS and BFTEFE produced the best results when measuring posterior elevation at the thinnest point. BFTE had better sensitivity with the RMS-P. From all measurements, best sensitivity (100%) was achieved with a cutoff point of 8 μm of posterior elevation at the thinnest point using the BFTEFE. BFTE was found to hide the cone in certain patients. Conclusions Posterior elevation measured at the thinnest point with a BFTEFE is the best-performing parameter and, therefore, is recommended to discriminate between normal and KC patients within a myopic population.

Keratoconus Prevalence Among High School Students in New Zealand

To determine the prevalence of keratoconus among high school students in Wellington, New Zealand. The Wellington Keratoconus Study was a population-based prospective cross-sectional study of 2 cohorts in Wellington: cohort 1 (year 9 students, mean age 13.9 years) and cohort 2 (year 11 students, mean age 15.5 years). A total of 1916 students with a mean age of 14.6 years participated from 20 schools in the region. Keratoconus was found in 1:191 (0.52%) participants overall and in 1:45 (2.25%) Maori participants. Pentacam mean Kmax of 48.7 diopters (D) (cohort 1, 45.5 D; cohort 2, 49.9 D), thinnest pachymetry of 494.05 μm (cohort 1, 479.0 μm; cohort 2, 499.5 μm), posterior elevation at the thinnest point of 23.4 (cohort 1, 15.2; cohort 2, 26.6), Belin/Ambrosio enhanced ectasia display overall D value of 4.30 (cohort 1, 3.2; cohort 2, 4.7) were noted in participants with keratoconus. In those with keratoconus, 8 of 10 had visual impairment of 0.2 Logarithm of the Minimum Angle of Resolution (LogMAR) or worse in the better eye; 7 of 10 did not use visual aids; 7 of 10 had atopy; and 6 of 10 were from a low school decile. In those without keratoconus, 43.8% had atopy. Keratoconus may affect up to 1 in 191 New Zealand adolescents and 1 in 45 Maori adolescents. Keratoconus appeared to be associated with Maori ethnicity, atopy, lower school decile, visual impairment, and the underutilization of visual aids. Nationwide screening programs may have a role in reducing the burden of disease associated with keratoconus.

Comparison of eye-rubbing effect in keratoconic eyes and healthy eyes using Scheimpflug analysis and a dynamic bidirectional applanation device

To compare the effect of eye rubbing on Scheimpflug imaging parameters and corneal biomechanics in eyes with keratoconus and healthy eyes. Oftalmosalud Instituto de Ojos, Lima, Peru. Prospective cohort study. The study included healthy and keratoconus patients who attended the institution between January 2017 and July 2017. Eye rubbing was performed for 1minute followed by a 5-second break, followed by further rubbing for 1minute. Baseline tests were performed before rubbing; post-rubbing tests were performed immediately after (0minutes), and then again at 7minutes and 14minutes. Parameters related to anterior and posterior curvature and elevation, pachymetry, and corneal biomechanics obtained from tomography with a rotating Scheimpflug camera (Pentacam HR) and a dynamic bidirectional applanation device (Ocular Response Analyzer) were measured and compared between healthy and keratoconic eyes. The study included 30 healthy eyes and 31 keratoconic eyes. In the healthy group, the immediate mean changes in steeper anterior keratometry, posterior astigmatism, anterior chamber volume (ACV), flattest posterior keratometry, and Goldmann-correlated intraocular pressure (IOPg) after eye rubbing were 0.07 diopters (D)±0.15 (SD), -0.01±0.08 D, 0.03±7.06mm3, -0.001±0.04mm, and -1.21±1.99mm Hg, respectively, whereas the mean changes in the keratoconus group were -0.03±0.32 D, 0.14±0.50 D, -5.09±8.45mm3, 0.03±0.06mm, and -1.61±1.41mm Hg, respectively. There were statistically significant differences between the preoperative and postoperative eye-rubbing values of posterior astigmatism, ACV, and IOPg in the keratoconus group (P=.03, P=.0003, and P=.001, respectively) but not in the healthy group (P=.65, P=.85, and P=.23, respectively). Unlike the healthy eyes group, the keratoconus group experienced significant changes in ACV, IOP, and corneal posterior astigmatism after eye rubbing.