Scheimpflug Imaging System Research Articles

Three-dimensional ghost imaging via the Scheimpflug detection.

For previous three-dimensional ghost imaging, the acquisition of absolute distance information is mainly based on the principle of time-of-flight, which usually needs lots of measurements and a large detection/modulation bandwidth product. Here we present a technique called three-dimensional ghost imaging via the Scheimpflug detection (3D-GISD), which exploits the principle of a similar binocular stereoscopic vision for distance information acquisition and can dramatically reduce the measurements required for high-quality 3D image reconstruction. The experimental results demonstrate that high-quality 3D-GISD can be still obtained even if the target exceeds the depth of field of Scheimpflug imaging system and less than 500 measurements are adopted for an image with 128×128 pixels. What's more, the ranging accuracy of 0.2 mm can be achieved by 3D-GISD at about 1.1 m detection distance for a real scenario. Factors influencing the accuracy of distance measurement for 3D-GISD are also discussed.

Integrated line-field optical coherence tomography and scheimpflug imaging for corneal imaging

Previously we demonstrated a combined scanning-point optical coherence tomography (OCT) and Scheimpflug Imaging (SI) system, to provide cross-section images of the corneal layers and the whole anterior segment of the eye simultaneously. However, to fully realise the benefits of this dual imaging modality concept towards clinical practice, it is required that the OCT part of the system can achieve ultra-high axial resolution (<3 µm in air) and faster imaging speeds, without using prohibitively expensive components. To achieve this, a new imaging device integrating line-field OCT and SI, using a supercontinuum light source, is demonstrated. This line-field configuration enables both OCT and SI B-scan to be captured using the same light illumination in a single shot, which is the most significant improvement over single point scanning. This achieves an OCT axial resolution down to 2.1 µm in air (1.6 µm in corneal tissue) and an imaging speed up to 213 kA-Scans/s. Since the OCT and SI capture the identical corneal position and serve as cross-validation, this technique offers a great method for accurately determining the individual corneal thickness and refractive index, thereby minimizing individual variations, which can help determine the extent of cutting or correction needed in vision correction. Moreover, the precise measurement of corneal thickness provided by this technique allows for a better understanding of the biomechanical properties of the cornea. We demonstrate the efficacy of the proposed system by evaluating porcine and bovine eyes ex-vivo for determining the corneal refractive index and thickness.

Evaluation of corneal densitometry values with Pentacam in cases of ocular hypertension and pseudoexfoliative glaucoma

BackgroundExamination of corneal densitometry measurements using the Pentacam Scheimpflug imaging system in cases of pseudoexfoliative glaucoma (PEXG) and ocular hypertension (OHT). MethodsThe study included 50 eyes of 29 PEXG patients, 25 eyes of 16 OHT patients, and 76 eyes of 38 healthy control subjects followed in the glaucoma clinic. Corneal densitometry values of all cases were measured using the Scheimpflug imaging system (Pentacam, Oculus, Germany). Corneal densitometry was assessed based on 4 concentric radial zones (0–2 mm, 2–6 mm, 6–10 mm, and 10–12 mm) and depths (anterior, central, posterior, and total) within the Scheimpflug imaging system. The results were statistically analyzed. ResultsCorneal densitometry values examined between the OHT and control groups were higher in OHT and statistically significant (p < 0.05). Corneal densitometry values examined between the PEXG and control groups were higher in PEXG and statistically significant (p < 0.05). In comparison between the PEXG and OHT groups, corneal densitometry values in the central 0–2 mm, 2–6 mm, and 6–10 mm; posterior 0–2 mm and 2–6 mm radial zones were higher in PEXG and statistically significant (p < 0.05). ConclusionsIt was observed that elevated intraocular pressure levels in OHT cases could lead to changes in the cornea, consequently increasing corneal densitometry values. The higher corneal densitometry values in PEXG cases compared to OHT were attributed to the accumulation of pseudoexfoliative material in the cornea. Based on our study, corneal densitometry could serve as a potential biomarker for early glaucoma detection in OHT cases and could be employed to assess corneal transparency during the follow-up of PEXG cases.

Corneal and anterior segment parameters in patients with clinically unilateral pseudoexfoliation syndrome.

Pseudoexfoliation syndrome (PES) is an age-related systemic condition that predominantly affects ocular structures and is characterized by the deposition of material on the lens, ciliary body, zonules, corneal endothelium, iris, and pupillary margin. We compared the corneal endothelial morphology, anterior segment parameters, corneal densitometry, and corneal topographic characteristics between the clinically affected and apparently normal fellow eyes of patients with clinically unilateral PES. This was a comparative, cross-sectional study of 34 patients with clinically unilateral PES. The anterior segment was examined using a Scheimpflug imaging system, and the corneal endothelium was assessed using a noncontact specular microscope. Corneal endothelial cell density, polymegathism, and pleomorphism were assessed using the specular microscope. Furthermore, the Scheimpflug camera was used to measure the corneal power of the flat and steep axis, mean corneal power, maximum keratometry, anterior chamber angle, anterior chamber depth, anterior chamber volume, corneal volume, and the corneal thickness at the apex point, center of the pupil, and the thinnest point. Corneal densitometry was evaluated at two concentric zones (0-2 mm and 0-12 mm). In total, 68 eyes from 34 patients were ultimately included in the study. The mean (standard deviation) age of the patients was 73.38 (8.75) years (range: 50-87 years). Among the included patients, 17 (50%) were male and 17 (50%) were female. The anterior segment parameters did not significantly differ between eyes with PES and their clinically unaffected fellow eyes (all P > 0.05). Similarly, no statistically significant difference was observed in corneal endothelial morphology (all P > 0.05). Our measured parameters do not differ between the clinically affected eye and the clinically unaffected fellow eye. This supports the theory that PES is a bilateral disorder. Considering the variety of complications associated with PES, bilateral involvement should be assumed in the clinical and surgical management of patients with clinically unilateral PES. In the future, new research could increase our understanding of this syndrome.

Comparison of two swept-source optical coherence tomography devices, a Scheimpflug camera system and a ray-tracing aberrometer in the measurement of corneal power in patients with cataract

PurposeTo assess the differences and similarities in the corneal curvature obtained by two swept-source optical coherence tomography (SS-OCT) devices, Scheimpflug imaging system and one ray tracing aberrometer in patients with cataracts. Moreover, this study aimed to compare the differences in posterior corneal (PK), total corneal (TK) and true net power (TNP) measurements among the IOLMaster 700, CASIA2, and Pentacam.MethodsA total of 200 eyes of 200 patients (116 female, 58%) were enrolled in this study, with a mean age of 65.9 ± 9.5 years. The flattest (Kf), steepest (Ks), and mean cornal powers (Km), J0, and J45 were obtained using two SS-OCT-based biometric devices, one rotating camera system and one ray-tracing aberrometer. The PK, TK and TNP values were also measured using these devices. To evaluate the differences and similarities between the devicves, the Friedman test, Pearson correlation coefficient (r), intraclass coefficient correlation (ICC) and Bland‒Altman plots with 95% limits of agreement (LoA) were used, and boxplots and stacked histograms were generated to describe the distributions of the data.ResultsThere were no significant differences between the IOLMaster 700 and Pentacam for any of the keratometry values. Additionally, there were no significant differences between the IOLMaster 700 and iTrace in evaluating J0 and J45. Bland‒Altman plots revealed relatively wide LoA widths, almost larger than 1 diopter for the keratometry values and almost larger than 0.5 diopter for J0 and J45 values among the four devices. In terms of PK and TK values, significant differences and low ICCs were found among the three devices.ConclusionsAlthough strong correlations and good agreement were found among the IOLMaster700, CASIA2, Pentacam and iTrace for Kf, Ks, Km and J0, J45, it seems that the measurements should not be used interchangeably because of the wide LoA widths and the presence of significant differences among the devices. Similarly, due to significant differences and low ICCs, the PK, TK and TNP values obtained by IOLMaster 700, CASIA2, and Pentacam should not be used interchangeably.

Refractive Index Measurement of the Crystalline Lens in Vivo.

This study provides a new method to measure the refractive index of crystalline lens in the human eye in vivo . Accessing the refractive index of crystalline lenses in the human eye in vivo has long been a challenge. This study aimed to measure the refractive index of a lens in vivo using an anterior segment optical coherence tomography (AS-OCT) system combined with a Scheimpflug imaging system. A ray-traceable Scheimpflug imaging was developed and integrated into an AS-OCT system. A theoretical study revealed that the combination of these two systems provides a unique solution for simultaneously measuring the refractive index and the thickness of the lens. The average lens refractive index along the ray pathway ( Nav ) and lens shape were measured for seven subjects. The lens Nav along the central ray varies from 1.383 to 1.419 between subjects. The lens refractive index function across the lens diameter varies from subject to subject. The lens Nav increases for accommodated eyes. The thicknesses and profiles of the lenses are also determined. The lens refractive index varies substantially from individual eye to individual eye, not only along the central ray pathway but also for the lens refractive index function across the lens diameter. Ray-traceable Scheimpflug imaging-equipped AS-OCT is useful for testing the refractive index of lenses in the human eye in vivo .

How Does Pupil Size Affect Lens and Corneal Densitometry Measured by Scheimpflug Tomography?

To investigate the effects of pupil diameter on the evaluation of lens and corneal densitometry measured by Scheimpflug tomography. This cross-sectional and comparative study used the right eyes of 32 participants. Corneal and lenticular optical densitometries, corneal volume, anterior segment volume, and anterior chamber depth measurements were taken with the Scheimpflug imaging system when the pupils were mid-dilated and fully dilated. The results were statistically compared. The mean lens density was 19.20±3.05 when the pupils were mid-dilated (mean pupil diameter 2.98±0.89 mm) and 23.25±3.88 at full dilation (mean pupil diameter 5.01±0.92 mm) (p<0.001). The mean corneal density was 16.15±0.99 with mid-dilated pupils and 16.38±0.95 with fully dilated pupils (p=0.065). Anterior chamber depth and anterior segment volume measurements increased with larger pupil diameter (p<0.05). The lens densitometry values increased with an increase in pupil diameter. The corneal density measurements increased minimally but the differences were not statistically significant. This study revealed that lens densitometry was significantly affected by pupil diameter.

Corneal characteristics in patients with retinitis pigmentosa

BackgroundTo evaluate corneal topography and specular microscopic findings in patients with retinitis pigmentosa. MethodsOne hundred and two eyes of 51 patients with retinitis pigmentosa and 60 eyes of 30 healty subjects were included in our study. A detailed ophthalmological examination involving best corrected visual acuity (BCVA) was performed. A rotating Scheimpflug imaging system, was used to evaluate all eyes for topographic and aberrometrics parameters. Specular microscopy measurements were also noted. ResultsThe retinitis pigmentosa group consisted of 51 patients (29 male and 22 female, mean age of 35.61±13.55 (18–65) years and the control group also consisted of 30 healty subjects (29 male and 22 female, mean age of 33.67±9.92 (20–58) years. There was no difference between the groups in terms of age (p = 0.624) and gender (p = 0.375). Spherical equivalents were higher in the RP group (p<0.001). Central keratoconus index (CKI) (p<0.001), Belin Ambrosio enhanced ectasia display total deviation value (BAD-D) (p = 0.003), index of surface variance (ISV) (p<0.001), index of vertical asymmetry (IVA) (p<0.001), Ambrosio related thickness (ART max) (p = 0.018), index of height asymmetry (IHA) (p = 0.009), index of height decentration (IHD) (p<0.001), maximum anterior elevation (p<0.001), front elevation in thin location (p = 0.05), progression index average (p = 0.015), root mean square (RMS) total (p = 0.010) and RMS-higher order aberration (RMS-HOA) (p<0.001) values were higher in RP group. There was a weak negative correlation between BCVA and ART max measurements (r=-0.256, p = 0.009) in RP group. We detected keratoconus-suspect in 6 eyes and clinically manifest keratoconus in one eye in the RP group. ConclusionsPatients with retinitis pigmentosa may have corneal morphological disorders that may affect vision. In our study, corneal topographic pathologies including keratoconus and possible keratoconus were detected in RP patients.

Corneal optical density: Structural basis, measurements, influencing factors, and roles in refractive surgery.

The cornea is the main refractive medium of the human eye, and its clarity is critical to visual acuity. Corneal optical density (COD) is an important index to describe corneal transparency. Intact corneal epithelial and endothelial cells, regular arrangement of collagen fibers in the stroma, and normal substance metabolism are all integral for the cornea to maintain its transparency. In the last two decades, the Pentacam Scheimpflug imaging system has emerged as a breakthrough for the measurement of COD (also called corneal densitometry). It has been found that a wide variety of factors such as age, refractive status, and corneal diseases can affect COD. Different corneal refractive surgery methods also change COD in different corneal regions and layers and affect visual acuity following the surgery. Thus, COD has gradually become a significant indicator to evaluate corneal health, one on which the attention of clinicians has been increasingly focused.

Correlation between automated assessment of senile cataract density and the applied ultrasound energy during phacoemulsification

Introduction. Cataract density is highly important factor when choosing a surgical method and setting the parameters of a phacoemulsification device. Diagnostic devices enable automated assessment of lens opacification degree. Material and Methods. Study included 30 patients operated on for senile cataracts at the Clinic of Eye Diseases of the University Clinical Center of Vojvodina. After determining the preoperative best corrected visual acuity, cataract density was assessed using the Pentacam Nucleus Staging scale of the Scheimpflug imaging system, Pentacam AXL Wave (Oculus, Wetzlar, Germany). The evaluation of the applied ultrasound energy during phacoemulsification was quantified and expressed in the form of Cumulative Dissipated Energy index of the Centurion Vision System (Alcon, Irvine, USA) eye microsurgery device. The obtained results are expressed in the form of mean values, and their connection is presented in the form of correlation. Results. Statistically significant positive correlation was found between the cataract density expressed with use of the Pentacam Nucleus Staging scale and the applied ultrasound energy during surgery, expressed in the form of Cumulative Dissipated Energy index (r=0.37, p=0.04). No statistically significant correlation was found between preoperative best corrected visual acuity and cataract density expressed with the Pentacam Nucleus Staging scale (p&gt;0.05) or between preoperative best corrected visual acuity and Cumulative Dissipated Energy index (p&gt;0.05). Conclusion. The obtained data indicate a positive correlation (r=0.37, p=0.04) between the degree of lens opacification assessed by Pentacam Nucleus Staging scale and the required ultrasound energy applied during phacoemulsification expressed as Cumulative Dissipated Energy index.

Analysis of corneal topographic and densitometric properties in patients receiving systemic isotretinoin therapy

Purpose To evaluate dry eye parameters, corneal topographic features, corneal densitometric changes, and anterior segment parameters in patients receiving systemic isotretinoin treatment. Methods This prospective cross-sectional study included 66 eyes of 33 patients who were started on oral isotretinoin therapy for severe acne vulgaris. All patients were evaluated in terms of ocular surface tests such as tear break-up time (TBUT) and Schirmer-1 and were asked to fill in the ocular surface disease index (OSDI) questionnaire. Corneal densitometric and topographic measurements were obtained using the Scheimpflug imaging system. Results The mean age of the patients was 19.9 ± 1.6 years, and 21 (63.6%) of the participants were female. The mean OSDI score was significantly higher in the third month than before treatment (20.05 ± 19.38, vs. 26.96 ± 22.94, p = 0.00, respectively). The mean values of the TBUT test were significantly lower in the third month than before treatment (9.06 ± 4.40 sec, vs. 10.71 ± 4.61 sec, p = 0.02, respectively). Mean scores of the Schirmer 1 test showed no statistically significant difference between before treatment and the third month (16.08 ± 8.40 mm, vs. 16.08 ± 8.50 mm, p = 1, respectively). There was no statistically significant difference between before treatment and the third month in the majority of the densitometry measurements in concentric zones. However, the difference tended to be significant between the groups concerning posterior zone 0–2 mm (11.01 ± 0.85 GSU vs. 10.62 ± 0.89 GSU, p = 0.006). The RMS LOAs (front), RMS Total (Total), RMS LOAs Total (Total), RMS HOAs Total (Total), K max, CCT, and CoV values were significantly higher in the third month than before treatment (p < 0.05 for all). Conclusions The dermatology specialists should be aware of the ocular complications of systemic isotretinoin therapy. Therefore, a complete ophthalmologic examination for the prompt apprehension and management of ocular involvement is essential in patients under isotretinoin therapy to increase ocular comfort and adherence to the therapy.

Çocuk ve erişkin Keratokonus hastalarında hızlandırılmış çapraz bağlama tedavisi sonrası Scheimpflug Kornea Dansitometri analizi

Amaç: On sekiz yaş altı ve 18 yaş üstünde keratokonus nedeniyle çapraz bağlama tedavisi (ÇB) uygulanan hastalardaki korneal dansitometri değişimlerini karşılaştırmalı olarak değerlendirmektir. Yöntem: Keratokonus tanısıyla ÇB uygulanan 55 hastanın 74 gözü çalışmaya alındı. 18 yaş ve altındaki hastalar grup 1’e dahil edilirken, 18 yaş üstündeki hastalar grup 2’ye dahil edildi. Hastaların ÇB öncesinde ve sonrasında Pentacam Scheimpflug görüntüleme sistemi ile kornea kalınlığı ve korneal dansitometri değerleri ölçülerek kaydedildi. Çapraz bağlama sonrası tüm hastaların kornea kalınlıkları ultrasonik pakimetri ile de ölçüldü ve Scheimpflug sistem ölçümleri ile karşılaştırma yapıldı. Bulgular: Grup 1’de ÇB öncesindeki korneal dansitometri değeri 19.84±2.67 GSU iken, işlem sonrası 21.54±3.32 GSU idi ve aradaki fark istatistiksel olarak anlamlıydı (p=0.048). Benzer şekilde Grup 2’deki dansitometri değeri ÇB öncesinde 18.74±1.56 GSU iken, işlem sonrasında 24.53±10.46 GSU idi ve aradaki fark anlamlıydı (p&amp;lt;0.0001). Grup 1’de Scheimpflug görüntüleme sistemi ile ÇB öncesi ölçülen kornea kalınlığı 473.04±24.23 µ iken, grup 2’de 467.89±29.09 µ idi. Her iki grupta ÇB sonrası kornea kalınlıkları sırasıyla 461.88±27.64 µ ve 446.42±32.76 µ idi ve aradaki fark iki grupta da istatistiksel olarak anlamlıydı (sırasıyla p=0.003, p&amp;lt;0.0001). Sonuç: Keratokonus hastalarında, ÇB sonrasında, çocuk ve erişkinlerde korneal bulanıklık oluşmaktadır. Erişkinlerde çocuklara göre daha fazla bulanıklık olmaktadır. Bulanıklığın takibinde korneal dansitometri objektif veriler sunar. Bulanıklık olan kornealarda kalınlık takibi için ultrasonik pakimetri, Scheimpflug kameraya göre daha doğru ölçümler sunabilir.

Evaluation of the corneal morphologic and topographic alterations in patients with Bell’s palsy

Purpose: To evaluate the effects of ocular surface changes that may develop due to Bell’s palsy (BP) on dry eye parameters, corneal densitometry values, and aberrations in patients with unilateral BP and compare them with sound eyes.&#x0D; Materials and Methods: A total of 33 eyes of 33 patients diagnosed with unilateral BP and 33 sound fellow eyes of the patients were enrolled in this study. A complete ophthalmologic examination including best-corrected visual acuity (BCVA), intraocular pressure measurement, slit-lamp biomicroscopy to observe superficial punctate keratopathy (SPK), tear break-up time (TBUT) test, and detailed fundoscopic examination was performed for all patients. The corneal topographic, densitometric, and aberrometric measurements were performed using the Pentacam Scheimpflug imaging system.&#x0D; Results: The mean age of 33 patients was 54.9±14.7 years of whom 19 (57.6%) were female; 14 (42.4%) were male. According to the House-Brackmann scale, the majority of the patients had grade II facial nerve palsy. The BCVA in the affected eye was lower and 0.74±0.23 compared to 0.87±0.21 in sound eyes (p=0.029). The mean TBUT was lower and 6.0±4.7 in eyes affected by BP compared to 8.7±4.0 in sound eyes (p=0.014). The SPK was present in 23 (69.7%) patients. The comparison of the corneal densitometry values revealed that the densitometry measurements in anterior concentric zones were slightly higher in affected eyes. Corneal aberrometric values were also slightly higher in affected eyes. No significant difference was observed between affected and sound eyes in terms of corneal keratometric, densitometric, and aberrometric values (p&gt;0.05, for all).&#x0D; Conclusions: Corneal exposure leading to visual complications, and lowering of the tear production may lead to dry eye in BP patients. The examination of the ocular surface to observe the ocular findings of BP is essential. The main priority of the ophthalmologist is to ensure adequate corneal protection to prevent undesired ocular outcomes.

Ocular anterior segment and corneal parameters evaluation in celiac disease

This observational case–control study evaluated the anterior ocular segment parameters of patients with celiac disease with a Scheimpflug imaging system and compared them with those of a healthy controls group, highlighting potential differences related to the underlying pathogenetic mechanisms of the disease. Seventy celiac patients and 70 healthy subjects were assessed with a comprehensive ophthalmological evaluation, including clinical history, Snellen best-corrected visual acuity, axial length (AL) measurements with IOLMaster, and anterior segment tomographic evaluation with Pentacam HR. The measurements of all keratometry values, astigmatism, steep axis, anterior and posterior Q value (asphericity), pupil diameter, pupil center, corneal apex, the thinnest point, corneal volume, anterior chamber depth from the epithelium, anterior chamber depth from endothelium, anterior chamber volume, and iridocorneal angle were also appraised. The two study groups were comparable and similar for gender, age, and AL, with no statistically significant differences regarding all analyzed tomographic parameters. Thus, ocular anterior segment parameters of celiac patients are not significantly different from those of healthy subjects, suggesting no underlying pathogenetic implications of celiac disease affecting the assessed structures. Nevertheless, a routine ophthalmological examination for all celiac patients should be recommended throughout their lifetimes due to the potential ocular manifestations of the disease.

Corneal Ectatic Disease - Progression

Before the appearance of recent tomographic imaging and membrane cross-linking (CXL), identification and treatment of ectatic unwellness was restricted to disease severity during which changes to the anterior corneal surface resulted in visual disturbances. Rigid contact lenses and/or penetrating corneal transplant treated advanced disease, as a result of early or subclinical identification of disease wasn't doable or its necessity was appreciated. The emergence of cardinal as a viable treatment to switch the natural progression of astigmatism has enlarged the requirement for higher diagnostics. Many strategies are delineated within the literature to assess and document the progression of keratoconus, however there's no consistent definition of the progression of ectasia. the foremost recent imaging techniques (eg tomography) have created it doable to notice ectatic unwellness early, before loss of vision and subjective disorders.Belin' ABCD classification/staging system was introduced on a Scheimpflug imaging system [Pentacam, (Oculus GmbH, Wetzlar, Germany)] to handle previous shortcomings. The ABCD system uses four parameters: anterior ("A") and posterior ("B" for the back) radius of curvature taken in an exceedingly three.0 metric linear unit optical zone targeted on the thinnest point, "C" is that the minimum membrane thickness and “D” vision of the most effective show distance. The primary 3 parameters (A, B, C) are mechanically generated objective measures that may be accustomed to confirm progressive change.The staging system isn't restricted to a selected industrial entity and might be incorporated in any tomographic imaging system. The ABCD Pro- gression show diagrammatically displays every parameter and shows once applied mathematics amendment on top of measuring noise is reached. this {could} permit the practician the power to diagnose progressive unwellness at a far earlier stage than was antecedently possible, with the arrogance that earlier intervention could stop visual loss.

Objective Assessment of Corneal and Lens Clarity in Patients with COVID-19.

The severe acute respiratory syndrome coronavirus 2 virus, which causes the coronavirus disease 2019 (COVID-19) pandemic, can bind to epithelial cells in the human cornea and conjunctiva, which may result in changes of corneal and lenticular densitometry. We aimed to report the corneal and lenticular clarity of patients who had been diagnosed previously with confirmed infection of COVID-19. This was a prospective, cross-sectional study. Fifty-three patients who had recovered from COVID-19 and 51 healthy individuals who had not had COVID-19 (control) were included in this study. Measurement of the corneal (at a corneal diameter of 12 mm) and lens densitometry of participants was performed using a Pentacam HR Scheimpflug imaging system. Three different optimal depths as anterior, central, and posterior layers and four concentric zones, consisting of diameters of 0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm, were chosen to perform the corneal densitometric measurements. The mean lenticular densitometric values were calculated in zone 1 at 2.0 mm, zone 2 at 4.0 mm, and zone 3 at 6.0 mm by taking the central part of the pupil as reference point. When compared with the individuals in the control group, the corneal densitometry measurements in the patients in the COVID-19 group were considerably higher in anterior 0 to 2 mm, 2 to 6 mm, 6 to 10 mm zones and total diameter; center 0 to 2 and 2 to 6 mm zones and total diameter; posterior 0 to 2 mm zone; and total corneal 0 to 2 and 2 to 6 mm zones and total diameter (P < .05, for each). When compared with the individuals in the control group, all of the lens densitometry measurements, except for those located in zone 1, were determined to be significantly higher among the patients in the COVID-19 group (P < .05, for each). Significant alterations were found in corneal and lenticular densitometric values in patients who had had COVID-19. The virus could adversely affect cornea and lens transparency.

Consequences of seasonal allergic conjunctivitis on ocular parameters of anterior and posterior segments: An up-to-date imaging approach.

To investigate consequences of seasonal allergic conjunctivitis (SAC) on the ocular anterior and posterior segment parameters. Forty healthy participants (mean age: 25.90 ± 5.7 years, 20 females, 20 males) and 40 patients with SAC (mean age: 26.20 ± 5.7 years, 20 females, 20 males) were included in this prospective study. The anterior segment parameters including central corneal thickness (CCT) and anterior chamber depth (ACD) were measured by Scheimpflug imaging system. Axial length (AL) was measured by optical biometry. The posterior segment parameters, including retinal nerve fiber layer (RNFL), subfoveal choroidal thickness, and central macular thickness were measured by optical coherence tomography. Similar values of the ACD, AL, RNFL as well as central macular thickness between healthy participants and patients with SAC were revealed. Despite the CCT being thinner in SAC, there was no statistically significant difference between the two groups. On the other hand, SAC was found to be associated with an increase in subfoveal choroidal thickness, the condition of which may be attributed to the inflammatory nature of the disease. The present study has managed to demonstrate non-significant alterations in the ocular anterior and posterior segment parameters of patients with SAC. Yet, the increase in subfoveal choroidal thickness may be linked to the accompanying inflammation of both the conjunctiva and other ocular tissues, particularly the choroidal layer.

Analysis of corneal densitometry and endothelial morphometry in patients with psoriasis

BackgroundTo evaluate corneal endothelial properties and corneal densitometry values in patients with psoriasis and to compare the results with those of healthy controls. MethodsThis prospective, comparative, and cross-sectional study included 106 eyes of 53 patients who were diagnosed with psoriasis and 106 eyes of 53 age-gender matched healthy controls. All patients were evaluated in terms of ocular surface tests such as Schirmer-1 and tear break-up time (TBUT). Corneal endothelial measurements were performed using noncontact specular microscopy. Corneal tomographic and densitometric measurements were obtained using the Scheimpflug imaging system. Measurements were also evaluated according to the psoriasis area and severity index (PASI) score. ResultsThe mean TBUT and Schirmer 1 test values were significantly lower in the psoriasis group than in the healthy controls (p = 0.02, p < 0.001, respectively). While the mean endothelial cell density was significantly lower in patients with psoriasis than the healthy controls (2389.9±314.9 cells/mm2 vs. 2512.4±289.7 cells/mm2, p = 0.02), the mean average endothelial cell area, standard deviation of cell area, coefficient of variation of cell area were significantly higher in patients with psoriasis (426.6±62.7 µm2 vs. 403.2±46.1 µm2, p = 0.01; 206.4±52.3 µm2 vs. 183.2±43.8 µm2, p = 0.006; and 48.1±6.3% vs. 45.7±6.7%, p = 0.04, respectively). Most of the densitometry measurements in concentric zones were higher in patients with psoriasis than in healthy controls, but none of the differences reached statistical significance. ConclusionsA regular eye examination is crucial in patients with psoriasis because corneal structural and functional changes, particularly endothelial alterations, are of utmost importance in planning intraocular surgeries in patients with psoriasis.

Changing perspectives

Changing perspectives

Comparison of total keratometry with corneal power measured by optical low-coherence reflectometry and placido-dual Scheimpflug system.

To compare the total keratometry (TK) and astigmatism measurements in eyes with cataract using automated keratometry of swept-source optical coherence tomography (ss-OCT), optical low-coherence reflectometry (OLCR), simulated keratometry (SimK), and total corneal power (TCP) of combined placido-dual Scheimpflug imaging system. The study was conducted at LV Prasad Eye Institute, Hyderabad, India. Retrospective evaluation of electronic medical records of patients who were evaluated for cataract surgery. Twenty-eight eyes of 28 patients were included in the study. All patients evaluated for cataract surgery underwent corneal power measurements using three devices: ssOCT, OLCR, and combined placido-dual Scheimpflug imaging were included in the study. Vector analysis was performed to evaluate corneal astigmatism and Bland-Altman analysis was conducted to evaluate the limits of agreement of similar parameters among devices. The mean TK was statistically significantly different from the keratometry obtained from optical biometers and values measured by the Scheimpflug imaging system. The magnitude of mean difference was greater between TK and TCP (0.75 ± 0.25) compared to other variables. The mean difference in astigmatism between TK, ss-OCT-K (0.09 ± 0.12, p = 0.48), OCLR-K (0.10 ± 0.48, p = 0.91), and TCP (0.09 ± 0.47, p = 0.31) was not statistically significant but was statistically significant between TK and SimK values (0.23D ± 0.49D). The axis of orientation (<20°) of astigmatism was comparable (100%, 28 eyes) between two keratometry variables measured by ss-OCT. There appears to be a greater correlation of automated keratometry, and TK values obtained from ss-OCT compared to other variables studied. The measurements from TK, Simk, and TCP cannot be used interchangeably.