Pentacam Oculus Research Articles

Keratoconus Detection in High-Astigmatism Pediatric Patients: Optimal Pentacam Indices and Cutoff Points.

To assess the accuracy of various Pentacam indices in distinguishing keratoconus (KC) in pediatric patients with high astigmatism and to establish appropriate cutoff values. This prospective multicenter cross-sectional study included 312 eyes from 167 patients aged 6 to 18 years (mean age, 13.1 ± 3.2 years) evaluated with Oculus Pentacam HR. Patients were categorized into 4 groups: KC, forme fruste keratoconus, astigmatism greater than 2 diopters (Cyl2D), and control. A subgroup of Cyl2D comprised patients with astigmatism greater than 4 diopters (Cyl4D). Twenty-three Pentacam indices were analyzed, and receiver operating characteristic curves determined optimal cutoff points, sensitivity, and specificity. The best indices for distinguishing KC from Cyl2D were high-order aberration root mean square of the anterior corneal surface (area under the receiver operating characteristic curve 0.987), Belin/Ambrosio enhanced ectasia total derivation (0.971), index of vertical asymmetry (0.971), average pachymetric progression index (0.962), maximum Ambrosio relational thickness (0.960), posterior elevation (0.952), and anterior elevation (0.948). The accuracy of these indices was highest in the control group and lowest in the Cyl4D group. Area under the receiver operating characteristic curve was significantly lower for fruste keratoconus than KC. Optimal cutoff values were higher for astigmatic patients than for those with no refractive error. Most indices effectively distinguished between KC and normal pediatric patients. For individuals with high astigmatism, we suggest focusing on specific indices such as high-order aberration root mean square, Belin/Ambrosio enhanced ectasia total derivation value, maximum Ambrosio relational thickness, average pachymetric progression index, and index of vertical asymmetry. Optimal cutoff points for these patients were higher than those for nonastigmatic children and differed from adult populations.

Comparison of the IOL Master and Pentacam in the measurement of anterior segment parameters in patients with high myopia and cataracts

This study aimed to compare the differences between the Zeiss IOL Master and Oculus Pentacam in keratometry and central anterior chamber depth (ACD) measurements in patients with high myopia and cataracts. Between January 2019 and December 2020, 89 patients (103 eyes) with cataracts and high myopia who underwent preoperative cataract evaluation at Nanchang First Hospital were selected for retrospective analysis. Keratometry (K1, K2) and ACD were measured with the IOL Master and Pentacam. Paired t-tests were performed to compare the differences, while the Bland-Altman method was used to evaluate the agreement. The K1 value was (43.15±2.44) D for the IOL Master and (42.98±2.47) D for the Pentacam, and the difference between the two instruments was statistically significant (P<0.01). The K2 value was (44.55±2.63) D for the IOL Master and (44.32±2.55) D for the Pentacam. The ACD was (3.44±0.33)mm for the IOL Master and (3.39±0.36)mm for the Pentacam. There were statistically significant differences between the two instruments in both keratometry and ACD (P<0.01). The absolute values of the maximum difference between the two instruments for K1 and K2 were 1.1 and 1.07; thus, the consistency of the two instruments with respect to this measurement was poor. However, the absolute value of the maximum difference between the two instruments for ACD was 0.34, so the consistency of the two instruments in relation to this measurement was good. Both the IOL Master and the Pentacam can be used in the measurement of keratometry and ACD in patients with high myopia and cataracts, but the keratometry measurements should be compared in clinical application.

Code-Free Machine Learning Approach for EVO-ICL Vault Prediction: A Retrospective Two-Center Study.

Establishing a development environment for machine learning is difficult for medical researchers because learning to code is a major barrier. This study aimed to improve the accuracy of a postoperative vault value prediction model for implantable collamer lens (ICL) sizing using machine learning without coding experience. We used Orange data mining, a recently developed open-source, code-free machine learning tool. This study included eye-pair data from 294 patients from the B&VIIT Eye Center and 26 patients from Kim's Eye Hospital. The model was developed using OCULUS Pentacam data from the B&VIIT Eye Center and was internally evaluated through 10-fold cross-validation. External validation was performed using data from Kim's Eye Hospital. The machine learning model was successfully trained using the data collected without coding. The random forest showed mean absolute errors of 124.8 µm and 152.4 µm for the internal 10-fold cross-validation and the external validation, respectively. For high vault prediction (>750 µm), the random forest showed areas under the curve of 0.725 and 0.760 for the internal and external validation datasets, respectively. The developed model performed better than the classic statistical regression models and the Google no-code platform. Applying a no-code machine learning tool to our ICL implantation datasets showed a more accurate prediction of the postoperative vault than the classic regression and Google no-code models. Because of significant bias in measurements and surgery between clinics, the no-code development of a customized machine learning nomogram will improve the accuracy of ICL implantation.

Agreement between IOLMaster 700 and Pentacam AXL for IOL power measurement in patients with high myopia.

The anterior segment in individuals with high myopia has different features compared to those without myopia. IOLMaster 700 and Oculus Pentacam AXL are two accurate optical biometers. Both devices measure the cornea differently and thus yield different results when measuring intraocular lens (IOL) power. The purpose of this study is to assess the agreement of the IOL power calculation between IOLMaster 700 and Oculus Pentacam AXL in patients with high myopia. A prospective, analytical cross-sectional study was conducted to assess the agreement between the IOL power calculation with IOLMaster 700 and Oculus Pentacam AXL. In this study, 44 eyes were examined using Oculus Pentacam AXL and IOLMaster 700, and IOL power was calculated using the Barret Universal II formula and the AMO Sensar AR40E. The Bland-Altman plot was used to evaluate the agreement between the two devices. Based on the IOLMaster 700 examination, 44 eyes with high myopia had axial lengths ranging from 26.05 to 34.02 mm. The mean IOL power was 8.26 ± 4.755 and 8.58 ± 4.776 based on IOLMaster 700 and Oculus Pentacam AXL, respectively. The Bland-Altman plot revealed good agreement between the two devices, with a mean difference of -0.3182 in the IOL power calculation and a 95% LoA of 0.88099-0.24462 with a 95% confidence interval. Both devices showed good agreement in the IOL power calculation in patients with high myopia.

Characterization the corneal transparency profile in SMILE-treated myopic patients with densitometry: A 7-year cohort study.

To investigate 7-year changes in corneal densitometry (CD) and its influencing factors following small incision lenticule extraction (SMILE) for moderate to high myopia. A total of 32 patients (52 eyes) with a mean spherical equivalent (SE) refraction of -6.30 ± 1.30 D who underwent SMILE were recruited for this prospective study. Pre- and postoperative CD and corneal aberrations were measured by an oculus Pentacam system, and patients were followed up to 7 years. The CD evolution over time and its influencing factors were explored. No complications were observed after SMILE. There was a significant time effect on postoperative CD ( P < 0.05). The CD values at the 0-to-2 and 2-to-6 mm of the anterior layer increased at the first day ( P < 0.05) and declined to baselines at 1 year postoperatively; after that, CD values at any zone and any corneal layer presented a decreasing trend over time (all P < 0.05). Multivariate analysis showed that postoperative CD was positively correlated with age and optical zone (OZ), whereas negatively correlated with SE, corrected distance visual acuity (CDVA), and corneal aberrations (higher-order aberrations, Coma0 and Coma90) (all P < 0.05). Generalized estimating equation revealed that age, SE, CDVA, OZ, and Coma0 were the main factors influencing postoperative CD values (all P < 0.05). CD manifested a long-term decreasing trend in moderate to high myopia treated with SMILE. Its main influencing factors are age, SE, CDVA, OZ, and Coma0.

Radiation Maculopathy in Patients with Malignant Melanoma of the Corpus Ciliare and Choroidea Following One-Day Session of Stereotactic Radiosurgery.

The aim of the thesis is to present the case of apatient in whom bilateral calcification of the hydrophilic intraocular lens (IOL) Lentis M+ LS-313 MF30 (Oculentis) has developed. Due to the negative effect on visual functions, explantation and replacement of the artificial lens was necessary in both eyes. Case Report: An overview of the available literature summarized the diagnostics, current examination methods and possibilities of the surgical solution of calcification of the bifocal hydrophilic lens Lentis M+ LS-313 MF30 (Oculentis). The specific solution is described in acase report of apatient in whom calcification of both lenses developed 6 years after implantation of the IOL. In 2015, the patient underwent uncomplicated cataract surgery of both eyes with the implantation of an artificial intraocular lens into the capsule. In September 2021, an 82-year-old man was examined at our outpatient clinic for deterioration of visual acuity and changes in the material of the artificial IOL which were perceptible during aclinical examination, on the recommendation of alocal ophthalmologist. Blurred vision predominated. Adiagnosis of intraocular lens opacification was confirmed and documented using aScheimpflug camera (OCULUS Pentacam HR) and anterior OCT (Avanti RTVue XR Optovue,). The patient was indicated for explantation and replacement of the opacified intraocular lens in the left and subsequently in the right eye- The same type of IOL was used for reimplantation with good functional results. Conclusion: Since 2010, multifocal lens implantation has been on an upward trend worldwide. This type of MF IOL has also been used in thousands of implantations. Anumber of other explantations can be expected in the coming years. The optimal solution is the correct replacement of the calcified IOL with the same construction made of safer hydrophobic material.

Long-term outcomes of tailored stromal expansion with refractive lenticule for crosslinking thin corneas.

To assess the long-term safety and stability of visual outcomes following the modified technique of collagen crosslinking (CXL) using refractive lenticule in eyes with thin corneas (<400 µm) and progressive keratoconus. A tertiary eye care hospital in India. Prospective, interventional case series. Eyes with progressive keratoconus and thin corneas (<400 µm) underwent CXL with intraoperative stromal augmentation using a refractive lenticule obtained from small-incision lenticule extraction (SMILE). Preoperative and postoperative evaluation (3 months, and then yearly thereafter) included corneal tomography (Oculus Pentacam), uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively), manifest refraction, and endothelial cell count (specular microscopy), and adverse events, if any, were noted. The patients were followed up for a period of 5 years. Seven eyes were included in the analysis. Mean corneal flattening of -4.29 D was noted from preoperative maximum keratometry (P = 0.018). An improvement in UDVA and CDVA of 0.38 logarithm of minimum angle of resolution (logMAR) and 0.36 logMAR, respectively, was noted at 5 years postoperative visit. Four eyes demonstrated a gain of two lines in CDVA. Mean spherical equivalent improved from -6.85 D preoperatively to -6.05 D at 5 years postoperatively. Clear demarcation line was noted between 230 to 270 µm on anterior segment optical coherence topography. No significant endothelial cell loss was noted postoperatively. Long-term outcomes demonstrated safety and disease stability following lenticule-assisted CXL.

Potential vision tester using adaptive optics, Maxwellian view, and small pupil.

We demonstrate a free-space, trolley-mounted potential vision tester (PVT), designed to study and improve the accuracy of visual acuity (VA) measurements in the aging eye. Key features include a high-resolution visual display presented in Maxwellian view, a 3 mm pupil to limit wavefront (WF) aberrations, and a moderate cost deformable mirror to induce or correct higher order optical aberrations. The visual display supported accurate measurement of visual acuities down to 20/5. The moderate cost, piezo deformable mirror induced seven nominal aberrations, calibrated as 0, -0.32, -0.23, + 0.27, and +0.39 microns spherical aberration; + 0.49 microns Y coma; and -0.51 microns X coma. A custom Hartmann Shack (HS) calibration (HSc) system demonstrated that induced aberrations were repeatable and stable. A Badal optometer provided the coarse focus. WF aberrations were measured for five normal subjects with a commercially available HS device (HSP) (OCULUS Pentacam AXL Wave), providing estimates of WF errors for 3 mm and other pupil sizes. VA was measured using four alternative forced-choice for a single black on white E stimulus in each trial. Using the method of constant stimuli yielded robust standard deviation measurements. The 50% fit for VA plotted against induced aberration resulted in linear functions for each subject for the range of our positive and negative spherical aberration data. Subjects differed, but higher order terms were unnecessary to describe data across spherical aberrations.

Repeatability and agreement of central corneal thickness measurements with a new handheld non-contact pachymeter.

To compare the repeatability of central corneal thickness (CCT) measurements taken with a new handheld pachymeter (Occuity PM1 pachymeter) and to assess its agreement with ultrasound biometry and two commercially available optical biometers in participants with normal eyes. Three consecutive CCT measurements of the right eye of 105 participants with normal corneas were acquired by the PM1 pachymeter, Lenstar LS 900 and Oculus Pentacam HR in a random order. This was followed by three measurements with a handheld ultrasound pachymeter (UP) (Pachmate 2). Repeatability and the repeatability limit were calculated for each device and Bland-Altman limits of agreement (LoA) were determined for the PM1 pachymeter compared to the other devices. The mean CCT (±SD) was 551.04 ± 33.43, 558.62 ± 31.46, 549.41 ± 31.00 and 539.73 ± 29.50 μm for the PM1 pachymeter, UP, Lenstar and Pentacam, respectively. The repeatability limits (expressed as the within subject SD for repeat measurements) were 14.02, 13.68, 4.99 and 9.90 μm, respectively. The closest agreement was between the PM1 and Lenstar (mean difference = -1.63 μm with LoA 10.72 μm below and 13.97 μm above the readings obtained with the Lenstar). The PM1 underestimated CCT compared to UP (mean difference = 7.58 μm, LoA 24.63 μm below and 9.47 μm above UP). The agreement was lowest between the PM1 and Pentacam (mean difference = -11.30 μm, LoA between 4.29 and 26.89 μm). The PM1 pachymeter shows excellent precision for CCT measurements across a range of corneal thicknesses in normal eyes and provides a safe and easy-to-use alternative to ultrasound pachymetry.

The effect of age on lens parameters and axial length among wide age range of Saudis: A prospective, cross-sectional study.

The purpose of the study is to establish normative values of eye parameters such as lens thickness (LT), lens diameter (LD), and axial length (AXL) among wide age range of Saudis using Pentacam AXL and compare these values between gender, in addition to that, to find the correlation between the age and those parameters. In this prospective cross-sectional study, we measured LT, LD, and AXL in 125 healthy Saudi controls aged between 8 and 60 years using OCULUS Pentacam AXL. The screening tests were performed for each subject to exclude any ocular abnormalities using slit lamp (Haag-Streit BQ 900), refractive error measured using auto refractometer (Topcon KR-1 Autorefractor/Keratometer), and subject who has spherical equivalent more than ± 4.00D and astigmatism more than 1.00DC was excluded from the study. The mean of three readings of LT, LD, and AXL was taken. All examination was applied on one eye (right eye). The overall mean and standard deviation of LT, LD, and AXL was 2.2 mm ± 0.5, 2.7 mm ± 0.6, and 23.8 mm ± 1.0, respectively. There was no statistically significant difference between males and females in these parameters in all age groups, except in Group 2 (age: 19-30 years), there was a statistically significant difference between males and females in AXL, mean difference (M = 0.48), and P = 0.015. The mean of LT and LD was negatively associated with age. However, there was no significant correlation between AXL and age. Normative values of LT, LD, and AXL have been established in wide age group of healthy Saudis; the findings of the present study can highlight not only the normal range of the different ocular parameters, namely LT, LD, and AXL, but also their variation with age and gender.

Refractive Outcome After Corneal Lenticule Implantation Ex Vivo Non-Human Study

Purpose To evaluate changes in corneal refractive parameters after implantation of a stromal lenticule of different thickness. We assume that the refractive outcome depends on the optical power of the used lenticule. Methods We conducted an ex-vivo non-human study on 33 normotonic porcine eyeballs divided into two groups, for 4D and 8D human lenticule implantation. Corneal stromal lenticules were obtained as a by-product from a laser procedure ReLEx SMILE. We evaluated corneal refractive parameters measured on Oculus Pentacam© device before and immediately after the intrastromal lenticule implantation. Results There was no statistically significant difference in corneal refractive parameters between the eyeball groups before lenticule implantation. In both groups, the intrastromal implantation in the depth of 300um led to a significant increase of central corneal pachymetry and corneal anterior steepening. In the 4D group the average central corneal pachymetry increased from 903 ± 124.59 to 1230 ± 148.99 (p = 0.0022) and in 8D group from 733.35 ± 69.60 to 1109 ± 161.64 (p = 0.0008). Induced changes in other studied parameters were not statistically significant, Kmax changed from 45.57 ± 2.78 to 72.07 ± 16.83 (p = 0.0094) and Km front from 40.72 ± 1.60 to 48.87 ± 5.83 (p = 0.0037) in 4D group and in the 8D group average Kmax increased from 42.22 ± 1.54 to 62.95 ± 12.67 (p = 0.0001) and K2 front 40.46 ± 1.64 to 51.51 ± 9.63 (p = 0.0037). There were no significant differences in refractive changes between the 4D and 8D groups after lenticule implantation. Conclusion Intrastromal corneal lenticule implantation induces changes in corneal refractive parameters. In both groups, the implantation induced a significant increase of an anterior corneal steepening without any significant influence on posterior corneal flattening. Corneal lenticule implantation did not lead to any significant change of corneal astigmatism. However, in order to have more precise data for future clinical applications we need to continue with the experiments and verify the results on human corneas.

Age-related changes in Scheimpflug corneal densitometry and their correlations with corneal topographic measurements in a healthy Chinese population.

Objective measurement of corneal densitometry (CD) values can be used to assess corneal transparency and health status, to investigate corneal diseases, and to review anterior segment surgeries. However, literature regarding the association between CD and corneal parameters in healthy adolescent and older individuals is limited. This study investigated age-related changes in Scheimpflug CD values and their correlations with age, sex, and corneal topographic parameters. This retrospective cross-sectional observational study included 347 eyes from 181 consecutive healthy Chinese participants aged between 5 and 90 years. They were divided into 9 age groups: 5-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, and 80-90 years. CD and corneal topographic measurements were measured using the Oculus Pentacam. To evaluate CD, the cornea was divided into 3 layers according to depth (anterior 120 µm, central, and posterior 60 µm), and into 4 annular regions according to diameter (0-2, 2-6, 6-10, and 10-12 mm). CD across different depths and regions was positively correlated with age (all P values <0.001). Of the 3 layers of corneal thickness, CD was highest in the anterior 120 µm and lowest in the posterior 60 µm (all P values <0.05). Among the 4 annular regions spanning the corneal diameter, the lowest CD values were 6-10, 2-6, and 0-2 mm at 5-29, 30-69, and 70-89 years, respectively. The highest CD values were 10-12 mm at 5-79 years, and 6-10 mm at 80-90 years (all P values <0.05). CD values of 10-12 mm in the anterior 120 µm corneal layer were significantly lower in men than in women (Z=-2.353; P=0.019). CD of 0-10 mm in each layer was not significantly different between sexes (all P values >0.05). Corneal topographic measurements, including flat-axis keratometry (K1), steep-axis keratometry (K2), and spherical aberration, were slightly positively correlated with age and CD (all P values <0.05). However, central corneal thickness (CCT) and thinnest corneal thickness (TCT), and age or CD showed no correlation (all P values >0.05). With age, CD, keratometry, and spherical aberration gradually increased, while the corneal thickness did not change significantly.

Clinical Study on Corneal Topographical Changes in Vernal Keratoconjunctivitis by Using OCULUS Pentacam®.

To evaluate the corneal topographical changes in vernal keratoconjunctivitis (VKC) subjects using OCULUS Pentacam. This was a cross-sectional study. VKC patients and normal subjects who fulfilled the inclusion and exclusion criteria were recruited by convenience sampling into the study. Subjects underwent a best-corrected visual acuity measurement with a Snellen chart, retinoscopy, and corneal topography (OCULUS Pentacam®), followed by anterior segment and fundus examination and intraocular pressure measurement. Data were collected and analyzed using SPSS version 26.0 for Windows (SPSS Inc. Chicago, IL, USA). A p-value <0.05 was considered statistically significant. A total of 78 eyes of 43 VKC patients and 84 eyes of normal subjects were included in the study. Most of the VKC subjects were Malay males aged 10 years or less. A majority (71.8%) had palpebral VKC of five years duration or less (57.7%) and presented between the ages of six and 10 years (44.9%). Central corneal curvature and astigmatism were significantly higher in VKC subjects compared to the normal population (p < 0.05). The minimal pachymetry was significantly lower with a longer duration of VKC (p < 0.05). Older age of presentation of VKC was associated with higher central corneal curvatures and thinner minimal pachymetry (p < 0.05). There was no association between the type of VKC and corneal topography changes. The prevalence of keratoconus and subclinical keratoconus among VKC subjects was 10.3% and 11.5%, respectively. Longer duration and older age of presentation of VKC are associated with significant corneal topographical changes, thus exposing them to a higher risk of the future development of keratoconus.

ICL Postimplantation Decentration and Tilt in Myopic Patients with Primary Iridociliary Cysts.

To observe the decentration and tilt of implantable collamer lens (ICL) as well as possible visual effects postimplantation in primary iridociliary cysts. The present investigation was a retrospective cohort study. All 48 patients (91 eyes) who underwent ICL surgery at the Center of Refraction Surgery of Tianjin Medical University Eye Hospital between July 2018 and May 2020 were split into two groups based on the absence or presence of primary iridociliary cysts established by ultrasonic biological microscopy (UBM) examination. Intraocular pressure (IOP), corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), anterior chamber angle (ACA), anterior chamber volume (ACV), and anterior chamber depth (ACD) were recorded preoperatively and postoperatively at 1, 6, and 12 months. Additionally, we performed an analysis of the ICL vault, decentration, and tilt using a rotating Scheimpflug Oculus Pentacam camera system at 1, 6, and 12 months after surgery. No serious complications were observed. Significant postoperative improvement (P < 0.05) of UDVA was established in the two studied groups; however, we did not observe statistically significant intergroup differences (P > 0.05) throughout the entire research period. In each group, the preoperative ACA, ACV, and ACD were statistically significantly reduced (P < 0.05), but no such decrease was established between their postoperative values (P > 0.05). We observed no statistical differences between both groups with regard to their values of IOP, ACA, ACV, ACD, ICL vault, ICL decentration, and tilt at 1, 6, and 12 months after surgery. Similarly, no statistically significant within-group correlation (P > 0.05) of the decentration of ICL and the tilt and the CDVA values was established. No postimplantation effect of ICL with a central hole on vision was established in myopia patients with primary iridociliary cysts, within certain limits of ICL decentration and tilt values.

Corneal stroma densitometry evolution in a clinical model of cellular therapy for advanced keratoconus

AbstractPurpose: To report the corneal stromal densitometry (CD) evolution studied by Scheimpflug tomography, anterior segment optical coherence tomography (AS‐OCT), and confocal microscopy changes, in keratoconus patients included in a clinical experience of advanced cell therapy using autologous humans adipose‐derived adult stem cells (ADASCs), and corneal decellularized or ADASCs‐recellularized human donor corneal laminas in advanced keratoconus.Methods: Interventional prospective, consecutive, randomized, comparative series of cases. Fourteen keratoconic patients were randomly distributed into three groups for three types of surgical interventions: group 1 (G‐1), autologous ADASCs implantation (n = 5); group 2 (G‐2), decellularized human corneal stroma (n = 5); and, group 3 (G‐3), autologous ADASCs + decellularized human corneal stroma (n = 4). Participants were assessed with Scheimpflug‐based Oculus Pentacam CD module, AS‐OCT (Visante, Carl Zeiss), and confocal microscopy (HRT3 RCM Heidelberg).Results: The central and total CD were statistically significantly higher in G‐2 compared with G‐1, and G‐3 compared with G‐1 at the studied annular zones centered on the corneal apex (0–2 mm, 2–6 mm, and 6–10 mm). There was statistical significance higher in G‐3 compared with G‐2 at the central corneal stroma at (0–2 mm, 2‐6 mm). The confocal microscopy findings, as well as the AS‐OCT reflected the densitometry changes.Conclusions: The intrastromal implantation of ADASCs produced very subtle changes in CD at the level of the central corneal stroma. However, the intrastromal implantation of decellularized corneal laminas increases it slightly, but with lower values than the implantation of recellularized laminas with ADASCs.

Comparison of Central Corneal Thickness Measurements with Four Different New Devices and Ultrasound Pachymetry

To assess the central corneal thickness (CCT) with 5 different devices, evaluate the repeatability of the devices, and determine the possible relationship between thickness values and sex. The study included 308 eyes of 154 patients (76 women, 78 men) between the ages of 18-30 who presented to the Ophthalmology Clinic of Muğla Sıtkı Koçman University Training and Research Hospital. Autorefractor (Topcon, Japan), ultrasound pachymetry (UP) (Ceniscan, USA), high-resolution Pentacam (Oculus, USA), anterior segment-optical coherence tomography (AS-OCT) (Optovue, USA), and Spectralis AS-OCT (Heidelberg, Germany) measurements were assessed. The mean age of the study participants was 23.2±0.2 years and the mean CCT was 540±14.1 μm, with no statistically significant difference in CCT between sexes (p&gt;0.05). Mean CCT values were 557.0±26.7 μm with the autorefractor, 543.6±32.9 μm with UP, 533.8±30.2 μm with the Oculus Pentacam, 519.8±30.1 μm with Optovue AS-OCT, and 547.5±31.6 μm with Heidelberg AS-OCT. Pairwise comparisons between devices showed that the Optovue AS-OCT gave significantly lower CCT measurements than the autorefractor and Heidelberg AS-OCT device (p=0.027 and p=0.033, respectively). The coefficient of repeatability for autorefractor, UP, high-resolution Pentacam, Optovue AS-OCT, and Heidelberg AS-OCT CCT measurements were 1.51%, 2.46%, 3.72%, 2.57%, and 3.34%, respectively. Measurements made with five different devices showed that CCT was comparable and clinically usable. However, it was determined that the Optovue AS-OCT showed lower CCT values compare to other devices. When compared in terms of repeatability, it was found to be lower in the Pentacam than other devices.

Prediction of corneal astigmatism based on corneal tomography after femtosecond laser arcuate keratotomy using a pix2pix conditional generative adversarial network.

PurposeThis study aimed to develop a deep learning model to generate a postoperative corneal axial curvature map of femtosecond laser arcuate keratotomy (FLAK) based on corneal tomography using a pix2pix conditional generative adversarial network (pix2pix cGAN) for surgical planning.MethodsA total of 451 eyes of 318 nonconsecutive patients were subjected to FLAK for corneal astigmatism correction during cataract surgery. Paired or single anterior penetrating FLAKs were performed at an 8.0-mm optical zone with a depth of 90% using a femtosecond laser (LenSx laser, Alcon Laboratories, Inc.). Corneal tomography images were acquired from Oculus Pentacam HR (Optikgeräte GmbH, Wetzlar, Germany) before and 3 months after the surgery. The raw data required for analysis consisted of the anterior corneal curvature for a range of ± 3.5 mm around the corneal apex in 0.1-mm steps, which the pseudo-color corneal curvature map synthesized was based on. The deep learning model used was a pix2pix conditional generative adversarial network. The prediction accuracy of synthetic postoperative corneal astigmatism in zones of different diameters centered on the corneal apex was assessed using vector analysis. The synthetic postoperative corneal axial curvature maps were compared with the real postoperative corneal axial curvature maps using the structural similarity index measure (SSIM) and peak signal-to-noise ratio (PSNR).ResultsA total of 386 pairs of preoperative and postoperative corneal tomography data were included in the training set, whereas 65 preoperative data were retrospectively included in the test set. The correlation coefficient between synthetic and real postoperative astigmatism (difference vector) in the 3-mm zone was 0.89, and that between surgically induced astigmatism (SIA) was 0.93. The mean absolute errors of SIA for real and synthetic postoperative corneal axial curvature maps in the 1-, 3-, and 5-mm zone were 0.20 ± 0.25, 0.12 ± 0.17, and 0.09 ± 0.13 diopters, respectively. The average SSIM and PSNR of the 3-mm zone were 0.86 ± 0.04 and 18.24 ± 5.78, respectively.ConclusionOur results showed that the application of pix2pix cGAN can synthesize plausible postoperative corneal tomography for FLAK, showing the possibility of using GAN to predict corneal tomography, with the potential of applying artificial intelligence to construct surgical planning models.

Keratoconus: current aspects of diagnosis and classification

Keratoconus (KC) is a progressive non-inflammatory ectatic corneal disease typified by corneal thinning and conical protrusion, as well as irregular astigmatism with a varying-degree visual impairment. A literature review on the disease epidemiology, classification and diagnosis is presented. Current clinical practice most commonly relies on the Krumeich’s adaptation of ABCD grading system by M. Belin and M. Amsler. The KC diagnosis requires a comprehensive approach that integrates a variety of methods. Scheimpflug imaging with the corneal biochemistry assessment is performed with a Pentacam Oculus keratotomograph in combination with a Corvis ST device. The result is expressed as diagnostic indices, CBI (Corvis Biomechanical Index), BAD-D (Belin/Ambrósio Enhanced Ectasia Index total deviation) and TBI (Tomographic Biomechanical Index). The use of optical coherence tomography is necessary to perform corneal epithelial thickness mapping as well as pachymetry to rule out hidden stromal thinning.

A novel homozygous ZNF469 variant causing brittle cornea syndrome is associated with corneal ectasias in heterozygous carriers.

To describe a family segregating a novel truncating ZNF469 homozygous mutation causing brittle cornea syndrome type 1 in a male patient and associated with corneal ectasia in his two heterozygous young children. A 49-year-old affected male and his 12- and 8-year-old, apparently healthy, siblings underwent phenotypic and genetic assessment. An Oculus Pentacam Scheimpflug topographer system was employed for keratometries and central corneal thickness measurements. Exome sequencing was performed in DNA from the index case with subsequent Sanger sequencing confirmation of the ZNF469 gene causal variant in his relatives. The index case had a history of bilateral keratoglobus, corneal perforations, bilateral hypoacusia, and skeletal anomalies. His two children exhibited topographic anomalies compatible with keratoconus suspects as well as mild skeletal anomalies. Genetic analysis identified a novel homozygous c.2340delC variant in the ZNF469 gene, which predicts a p.(Arg781Glufs*19) truncated protein. Sanger sequencing identified heterozygosity for the c.2340delC variant in DNA from both siblings. Our results expand the mutational spectrum associated with brittle cornea syndrome and provide the first demonstration of early corneal anomalies in subjects carrying monoallelic ZNF469 variants.

Cataract Grading in Pure Senile Cataracts: Pentacam versus LOCS III.

PurposeTo determine the diagnostic accuracy of Pentacam Cataract Grading Scale (PCGS) versus the Lens Opacities Classification System (LOCS III) in scaling pure age-related cataract.MethodsBetween April 2016 and May 2017, eyes of 281 patients were evaluated for grading of lens opacity. We used LOCS III and PCGS. Patients with pure age-related cataract with no previous history of eye surgery, eye trauma, or chronic systemic disease between 50 and 95 years of age were included. The examination of the patients was done, using slit lamp and LOCS III grading chart. The second examination was done a week later, using Oculus Pentacam. Next, we graded them using a PNS grading score. Spearman's rank correlation and a Bland-Altman Plot were implemented for analysis using MedCalc 14. 8.1. P O.05 was considered as statistically significant.Results Three hundred eyes were examined. Of them, 189 patients were male, and patients between 70 to 80 years old were the most common group. The correlation between grades of two methods was 0.47 (P 0.001). Results of the Bland-Altman plot showed a moderate alignment between the two methods.ConclusionThe association between LOCSIII and PCGS is not so favorable, however, it is an economical and effective method to assess lens opacities is LOCSIII. PCGS can be used in early diagnosis. For a definitive diagnosis and appropriate therapeutic intervention, an ophthalmological examination is needed.