Comparative Study of Primary SMILE, SMILE Enhancement, and Femtosecond Laser-Assisted LASIK on Higher Order Aberrations and Corneal Densitometry.

PURPOSE: To compare differences in corneal densitometry (CD) and higher order aberrations (HOAs) in eyes that underwent small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for the treatment of myopia and myopic astigmatism at postoperative months 3, 6, and 12, and to evaluate their changes in a separate cohort of eyes after SMILE enhancement. METHODS: In this prospective, randomized, paired-eye clinical trial, consecutive eligible participants were randomized to undergo SMILE or FS-LASIK in either eye. Main outcome measures were CD and HOAs preoperatively and at 3, 6, and 12 months postoperatively. A separate cohort of consecutive patients who had SMILE and underwent enhancement were also included for comparison. RESULTS: For CD, no significant differences were found between SMILE and FS-LASIK up to month 12. For HOA measured by wavefront aberrometry, both SMILE and FS-LASIK had an increase in total root mean square (RMS) HOAs, spherical aberration (SA), and vertical coma up to month 12. SMILE had an additional increase in vertical quatrefoil, and FS-LASIK had an increase in horizontal coma at month 12. FS-LASIK had higher SA than SMILE, whereas SMILE had higher vertical quatrefoil than FS-LASIK at month 12. Central and posterior zone CD had significantly decreased after SMILE enhancement compared to after primary SMILE up to 2 years after enhancement. RMS HOAs, lower order aberrations, and SA were all increased after SMILE enhancement compared to after primary SMILE. CONCLUSIONS: SMILE induced lower SA but higher vertical quatrefoil than FS-LASIK at 1 year. Both SMILE and FS-LASIK had similar increases in RMS HOAs and vertical coma up to 1 year. There were no differences in CD between both groups. SMILE enhancement additionally had decreased central and posterior CD but greater RMS HOAs and SA compared to primary SMILE. [J Refract Surg. 2024;40(5):e291-e303.].

Histogram-Based Densitometry Index to Assess the Severity of Interstitial Lung Disease in Systemic Sclerosis in Standard and Low-Dose Computed Tomography.

OBJECTIVE: Mean lung attenuation, skewness, and kurtosis are histogram-based densitometry variables that quantify systemic sclerosis-associated interstitial lung disease (SSc-ILD) and were recently merged into a computerized integrated index (CII). Our work tested the CII in low-dose 9-slice (reduced) and standard high-resolution computed tomography (CT) scans to evaluate extensive SSc-ILD and predict mortality. METHODS: CT scans from patients with SSc-ILD were assessed using the software Horos to compute standard and reduced CIIs. Extensive ILD was determined following the Goh staging system. The association between CIIs and extensive ILD was analyzed with a generalized estimating equation regression model, the predictive ability of CIIs by the area under the receiver-operation characteristic curve (AUC), and the association between CIIs and death by Kaplan-Meier analysis. RESULTS: Among 243 patients with standard and reduced CT scans available, 157 CT scans from 119 patients with SSc-ILD constituted the derivation cohort. The validation cohort included 116 standard and 175 reduced CT scans. Both CIIs from standard (odds ratio [OR] 0.53, 95% CI 0.37-0.75; AUC 0.77, 95% CI 0.68-0.87) and reduced CT scans (OR 0.54, 95% CI 0.35-0.82; AUC 0.78, 95% CI 0.70-0.87) were significantly associated with extensive ILD. A threshold of CII ≤ -0.96 for standard CT scans and CII ≤ -1.85 for reduced CT scans detected extensive ILD with high sensitivity in both derivation and validation cohorts. Extensive ILD according to Goh staging (OR 2.94, 95% CI 1.10-7.82) and standard CII ≤ -0.96 (OR 1.78, 95% CI 1.24-2.56) significantly predicted mortality; a marginal P value was observed for reduced CII ≤ -1.85 (OR 1.27, 95% CI 0.93-1.75). CONCLUSION: Thresholds for both standard and reduced CII to identify extensive ILD were developed and validated, with an additional association with mortality. CIIs might help in clinical practice when radiology expertise is missing.

[Analysis of indocyanine green plasma disappearance rate in clinical practice]. / Vybor metodiki opredeleniya skorosti plazmennoi eliminatsii indotsianina zelenogo v klinicheskoi praktike.

OBJECTIVE: To justify the optimal method for determining indocyanine green plasma disappearance rate (PDRICG). MATERIAL AND METHODS: We analyzed PDRICG in intensive care units. Indocyanine green was administered intravenously at a dose of 0.25 mg/kg. PDRICG was analyzed simultaneously by using of three methods: 1) PDD (PiCCO2 LiMON device), 2) SBS with analysis of plasma samples on precise spectrophotometer, 3) SBS with analysis of plasma samples on simple experimental photometer. RESULTS: PDD method was used for 346 PDRICG tests in 256 patients. Of these, 14.3% of measurements were erroneous. Paired tests using PDD and SBS methods were performed in 299 cases. SBS method resulted erroneous data in 0.6% of cases. Certain correlation (r=0.79, p<0.001) was found between the reference method (SBS with spectrophotometry) and the PDD method. Bland-Altman plot for these two methods showed that proportional bias of mean difference was caused by extremely high PDRICG of the PDD method (for example, more than 30%/min). Comparison of two SBS variants (spectrophotometer and experimental photometer) revealed good correlation (r=0.91, p<0.001). CONCLUSION: SBS method for measuring PDRICG ensures accurate results under mechanical interferences in patients with impaired capillary blood flow. This eliminates the need for redo measurement. Duplication of the PDD and SBS methods is recommended when repeating the test is not possible (organ donors).

The comparison of corneal densitometry in cases with glaucoma following childhood cataract surgery and juvenile glaucoma.

PURPOSE: To compare the corneal densitometry (CD) in pediatric cases with glaucoma following childhood cataract surgery and juvenile open-angle glaucoma (JOAG). METHODS: This prospective comparative study involved 13 eyes with JOAG, 12 eyes with pseudophakic glaucoma, 13 eyes with aphakic glaucoma, and 15 control subjects. Pentacam HR Scheimpflug corneal topography was employed to evaluate corneal thickness (CCT) and CD values. RESULTS: The mean intraocular pressure (IOP) and CCT were significantly higher in aphakic glaucoma cases than the other groups (p = 0.001). In aphakic eyes, the mean CD values were higher in most of the anterior, center, and posterior layers of 0-2 mm, 2-6 mm, 6-10 mm, and total zones (p < 0.001 for all). In pseudophakic eyes, the mean CD values were statistically similar with that of aphakic eyes and higher than that of JOAG and control eyes in all layers of 0-2 mm zone and in anterior layer of 10-12 mm and anterior and total layers of 2-6 mm zones (p < 0.05 for all). The CD values demonstrated significant correlations with CCT values in both aphakic and pseudophakic eyes. However, a significant correlation of CD values with IOP was only demonstrated in aphakic eyes (p = 0.01 for all). CONCLUSION: The probable effects of childhood cataract surgery especially aphakia might cause corneal backscatter of light and increased CD in all layers in all zones of the cornea. Increased CD values and its correlation with CCT and IOP in aphakic glaucoma eyes may be of importance in clinical management.

Quantitation of Mucin by Densitometry of an Alcian Blue-Stained Membrane.

It is a challenging task to quantify mucin using conventional protein quantification methods due to the large number of glycans attached to the peptide, which make up approximately 50-90% of its molecular weight. To address this issue, we propose a simple quantification method that involves spotting mucins onto a membrane and staining them with Alcian blue.

The improvement of routine drug quality control analysis of some antihypertensive drugs using high-performance thin-layer chromatography densitometry method with greenness profile evaluation.

The common antihypertensive drugs are B-blockers and diuretics. For the determination of beta-blocker medicines (bisoprolol fumarate and carvedilol) and diuretic drug (Furosemide), new and accurate chromatographic method has been developed. The separation was achieved using a developing system that includes chloroform:methanol:ethyl acetate:ammonia (6:2:2:0.2 by volume) as a mobile phase and the bands were detected at 240 nm. The concentration ranges were 5-25, 1-7, and 1-3.5 µg/band for bisoprolol fumarate, carvedilol, and furosemide, respectively. This chromatographic approach is the first methodology for simultaneously determining bisoprolol fumarate, carvedilol, and furosemide in their pure forms and in their pharmaceutical dosage forms. The advantages of using known analytical procedures are their simplicity, speed, cost effectiveness, lack of laboriousness, and ability to save time as the three tablets are determined in one step and can be used for routine analysis of the investigated combinations in quality control laboratories. According to International Conference of Harmonization guidelines, the established procedures have been validated, and the results were statistically compared to those obtained by the reported reversed-phase-high-performance liquid chromatography methods using Student's t-test and F-test, with no significant difference between them, indicating that the proposed methods can be used for routine drug quality control analysis.

Diagnostic Efficacy of High-Resolution Computed Tomography Densitometry for Diagnosing Otosclerosis.

OBJECTIVES: The purpose of this study is to evaluate the reliability of temporal bone density measurements for diagnosing otosclerosis. MATERIALS AND METHODS: A retrospective case-control study is presented. Bone density was measured in Hounsfield units (HUs) by using high-resolution computed tomography in eight regions of interest (ROI) where otosclerotic foci are usually localized. The density of 113 otosclerotic ears was compared with that of 33 nonotosclerotic ears to determine sensitivity and specificity. Furthermore, the binormal receiver operating characteristic curve of each ROI's density was calculated to estimate the diagnostic value for osteosclerosis. In addition, the radiological density of seven cases-where radiological visual examination exhibited no findings but surgery confirmed stapes fixation-was compared with nonotosclerotic controls. RESULTS: ROI densities were significantly lower in otosclerotic patients compared with nonotosclerotic controls. The area under the curve of the fissula ante fenestram (FAF) presented the highest diagnostic performance: 1,871 HU cut-off value (area under the curve = 0.986), 96.64% sensitivity, and 100% specificity. Significantly lower densities in the FAF area were observed in the seven cases with negative radiology but intraoperatively confirmed otosclerosis. CONCLUSION: The high-resolution computed tomography density of the FAF is a reliable measurement for diagnosing otosclerosis. A value less than 1,871 HU exhibited the highest sensitivity and specificity in a European Caucasian population.

Bone effects of epidural and intra-articular glucocorticoids: a systematic literature review / Efectos óseos de los glucocorticoides epidurales e intraarticulares: revisión sistemática de la literatura

Osteoporosis and vertebral and non-vertebral fractures are common in glucocorticoids (GC) treated patients. Oral GC treatment leads to bone loss, particularly of trabecular bone. The benefits of GC used in rheumatological and traumatological disorders are known but they would have possible negative effects on bone. This systematic review aimed to evaluate the effects of epidural steroid injections (ESI), and intra-articular and intramuscular GC administration on bone mineral density (BMD) and fragility fractures. A systematic review of Medline/PubMed, Cochrane, and LILACS up to November 2020 was conducted. Meta-analyses, systematic reviews, randomized and non-randomized controlled trials, and prospective and retrospective studies comparing the effect of ESI, intra-articular or intramuscular GC used compared to a control group or baseline measurements were included. Results: A total of 8272 individuals were included among the 13 selected articles (10 about ESI and 3 about intra-articular GC; no article was found evaluating intramuscular GC). Only a few studies showed a negative effect of ESI on bone in the qualitative analysis considering osteopenia and osteoporosis in lumbar spine, femoral neck and total hip and BMD as surrogate outcomes. On the other hand, the qualitative analysis showed that most studies found an increased risk of fragility fracture. However, only two studies could be included in the quantitative analysis, in which there were no differences between patients exposed to ESI versus controls in all evaluated regions. In conclusion, there was insufficient evidence to suggest that ESI and intra-articular GC, unlike oral GC, negatively affect bone mass. Longitudinal studies are needed to obtain more knowledge regarding the effect of ESI or intra-articular GC on BMD and fragility fractures. (AU)

La osteoporosis y las fracturas vertebrales y no vertebrales son comunes en pacientes tratados con glucocorticoides (GC). El tratamiento oral con GC conduce a la pérdida ósea, particularmente del hueso trabecular. Los beneficios de los GC utilizados en patologías reumatológicas y traumatológicas son conocidos, pero tendrían posibles efectos negativos sobre el hueso. Esta revisión sistemática tuvo como objetivo evaluar los efectos de las inyecciones epidurales de esteroides (ESI), GC intraarticulares e intramusculares sobre la densidad mineral ósea (DMO) y las fracturas por fragilidad. Se realizó una revisión sistemática de Medline/PubMed, Cochrane y LILACS hasta noviembre de 2020. Se incluyeron metanálisis, revisiones sistemáticas, ensayos controlados aleatorizados y no aleatorizados, estudios prospectivos y retrospectivos que compararon el efecto de ESI, GC intraarticular o intramuscular utilizado en comparación con un grupo de control o mediciones iniciales. Resultados: Se incluyeron un total de 8272 individuos entre los 13 artículos seleccionados (10 sobre ESI y 3 sobre GC intraarticular; no se encontró ningún artículo que evaluara GC intramuscular). Solo unos pocos estudios mostraron un efecto negativo del ESI sobre el hueso en el análisis cualitativo considerando la osteopenia y la osteoporosis en la columna lumbar, el cuello femoral y la cadera total y la DMO como un resultado indirecto. Por otro lado, el análisis cualitativo mostró que la mayoría de los estudios encontraron un mayor riesgo de fractura por fragilidad. Sin embargo, solo dos estudios pudieron incluirse en el análisis cuantitativo, en los que no hubo diferencias entre los pacientes expuestos a ESI versus los controles en todas las regiones evaluadas. En conclusión, no hallamos datos suficientes para sugerir que la ESI y los GC intraarticulares, a diferencia de los GC orales, afectan negativamente a la pérdida ósea. Se necesitan estudios longitudinales para obtener más conocimiento sobre el efecto de ESI o GC intraarticular en la DMO y las fracturas por fragilidad. (AU)

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

Objectives: To investigate the effects of pupil diameter on the evaluation of lens and corneal densitometry measured by Scheimpflug tomography. Materials and Methods: 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. Results: 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). Conclusion: 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.

Seven-year corneal densitometry changes after small incision lenticule extraction and femtosecond laser-assisted in situ keratomileusis.

This study aims to investigate the 7-year changes in corneal densitometry (CD) after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). Forty-two eyes undergoing SMILE and thirty-one undergoing FS-LASIK were included in this retrospective study. CD was measured preoperatively and at 3 and 7 years postoperatively. Three concentric radial zones (0-2, 2-6, and 6-10 mm) of three different corneal depths (anterior 120 µm, posterior 60 µm, and central layer) were analyzed. In all three zones of the three corneal layers, no significant difference in CD was found between the two groups preoperatively and at 3 and 7 years postoperatively (all P > 0.05). All CD values in the three zones of the anterior and central layers significantly declined at 3 years postoperatively (all P < 0.001), and then increased at 7 years postoperatively compared to corresponding 3-year values (all P < 0.01). In the posterior layer, CD values in the 0-2-mm and 2-6-mm zones decreased at 3 years postoperatively (all P < 0.01) and continued to decrease at 7 years postoperatively (all P < 0.01). Similar CD trends were observed after SMILE and FS-LASIK. Posterior layer CD showed a decrease throughout the study period. In the anterior and central layers, CD values decreased and then increased at 7 years postoperatively. The transparency changes might have been due to age-related three-dimensional growth of collagen fibers and wound-healing reactions.

Assessing Age-Related Changes in Corneal Densitometry Parameters With Anterior Segment OCT Speckle.

Purpose: The purpose of this study was to assess in vivo regional variability in the densitometry parameters of corneal stroma and the modulating effect of age on those parameters using statistical characterization of optical coherence tomography (OCT) speckle. Methods: OCT imaging of central and peripheral cornea was performed in a group of 20 younger (24 to 30 years old) and 19 older (50 to 87 years old) subjects. The sample size was estimated using normal assumptions and previously reported data on speckle parameter variability. Statistical parameters of corneal OCT speckle were calculated in the regions of interest (ROI) encompassing central and peripheral stroma as well as taking into account their anterior and posterior subregions. Both parametric (Burr-2 parameters: α and k) and a nonparametric approach (contrast ratio [CR]) were considered. Two-way analysis of variance was used to test for differences in densitometry parameters with respect to ROI position and age. Results: Both approaches showed statistically significant differences within the ROI positions (all P < 0.001 for α, k, and CR) and age (P < 0.001, P = 0.002, and P = 0.003, for α, k, and CR, respectively) indicating substantial stromal asymmetry. Additionally, CR showed statistically significant differences between anterior and posterior subregions (P < 0.001). Conclusions: Corneal OCT-based densitometry is inherently asymmetrical and are influenced by age. The results indicate that regional variability of stromal structure is not limited to the central and peripheral regions but that differences exist also between the nasal and temporal parts of the cornea. Translational Relevance: The in vivo acquired parameters of corneal OCT speckle can be used to indirectly assess corneal structure.

Effect of smoking on corneal and lens clarity: a densitometric analysis.

PURPOSE: To assess the effect of chronic cigarette smoking on corneal and lens densitometry measurements using Pentacam HR and to compare the results obtained with those in non-smokers. MATERIALS AND METHODS: This cross-sectional comparative study included 40 chronic-smokers and 40 age-matched healthy non-smokers between 18-40 years. After general ophthalmic examination, the Pentacam HR imaging system was used to evaluate corneal and lens densitometry measurements of smokers and non-smokers. RESULTS: The mean corneal densitometry values were not statistically significantly different in all the concentric zones and layers in the eyes of the smokers and non-smokers (p > 0.05, for all). However, the mean values of zone 1, zone 2, zone 3 and average lens densitometry measurements of the smokers were statistically significantly higher compared to non-smokers (p < 0.05, for all). Additionally, significant positive correlations were detected between the number of pack-years smoked and lens densitometry measurements. CONCLUSION: Lens densitometry measurements of smokers were significantly increased while corneal densitometry measurements were not significantly altered compared to non-smokers. Smoking may contribute to cataractogenesis and smoking and age-related changes may act synergistically to cataract development among smokers.

Analysis of Corneal and Lens Densitometry Changes in Patients With Type 1 Diabetes Mellitus.

PURPOSE: By comparing the densitometry findings of patients with type 1 diabetes mellitus (T1DM) and the healthy group, we aimed to understand the possible changes that may occur in the cornea and lens in those with diabetes mellitus (DM). DESIGN: Prospective, cross-sectional study. METHODS: A total of 60 eyes of 60 patients with T1DM and 101 eyes of 101 healthy subjects were included in this study. A complete ophthalmologic evaluation was performed in all participants. Scheimpflug tomography was performed to record the corneal and lens densitometry and other tomographic data. Mean glycosylated hemoglobin (HbA1c) and mean DM duration were recorded. RESULTS: The mean age of the patients with T1DM and patients in the control group was 29.93 ± 8.56 years and 27.27 ± 1 4.96 years, respectively. The mean HbA1c was 8.43 ± 1.92, and the mean DM duration was 14.10 ± 7.77 years. Corneal densitometry (CD) values were significantly higher in the 0- to 2-mm zone in all layers and in the anterior and central 6- to 10-mm zone in the diabetic group (P = .03, P = .018, P = .001, P = .000, P = .004). The mean crystalline lens densitometry was higher in the T1DM group (P = .129). There were positive correlations between DM duration and CD in the anterior 0- to 2-mm (P = .043), central 6- to 10-mm (P = .016), posterior 6- to 10-mm (P = .022), and posterior 10- to 12-mm zone (P = .043). CONCLUSIONS: CD values were significantly higher in the diabetic group. Diabetes duration and HbA1c values showed correlations with densitometry especially in the 6- to 10-mm corneal zone. Evaluation of the cornea with optical densitometry will be useful in the early diagnosis and follow-up of clinical structural and functional changes in the cornea.

Visual outcomes and corneal densitometry after allogenic and autologous lenticule intrastromal keratoplasty for the correction of moderate-to-high hyperopia.

AIM: This study aimed to evaluate the visual outcomes and corneal densitometry (CD) after allogenic lenticule intrastromal keratoplasty (AL-LIKE) and autologous lenticule intrastromal keratoplasty (AU-LIKE) for the correction of moderate-to-high hyperopia. METHODS: Ten subjects (14 eyes) underwent AL-LIKE and eight (8 eyes) underwent AU-LIKE. Patients were examined preoperatively and 1 day, 1 month, and 6 months postoperatively. The visual outcomes and CD for both surgical methods were evaluated. RESULTS: No postoperative complications were observed with either method. The efficacy index was 0.85±0.18 and 0.90±0.33 in the AL-LIKE and AU-LIKE groups, respectively. The safety indices were 1.07±0.21 and 1.25±0.37 in the AL-LIKE and AU-LIKE groups, respectively. The CD values of the anterior, central, and posterior layers in the AL-LIKE group increased significantly at 1 day postoperatively (all P < 0.05). The CD values of the anterior and central layers remained significantly higher than the preoperative values at 6 months postoperatively (all P < 0.05). The CD values of the anterior layer in the AU-LIKE group increased significantly 1 day postoperatively (all P < 0.05) and decreased to preoperative values (all P > 0.05) 1 month postoperatively. CONCLUSION: Both AL-LIKE and AU-LIKE exhibit good efficacy and safety in correcting hyperopia. However, AU-LIKE may have a smaller affected area and faster recovery time than those associated with AU-LIKE related to changes in corneal transparency.

Distribution of 50-layer corneal densitometry values and related factors.

PURPOSE: To investigate the distribution of 50 layers of corneal densitometry and related factors. METHODS: Clinical data, including age, sex, central corneal thickness, corneal keratometry, and diopters, were collected from 102 healthy participants (102 eyes) in this retrospective study. The cornea was divided into 50 layers, and densitometry of each layer at 19 points was measured by the Pentacam. The value versus the depth curve was plotted. Paired-sample t test and one-way analysis of variance were used to compare densitometry in different regions or depth. Statistical significance was defined as P < .05. RESULTS: The densitometry values of the Bowman membrane (10-14% depth), anterior stroma (14-30% depth), epithelium (0-10% depth), and Descemet membrane (94-98% depth) decreased sequentially, and the densitometry values of the middle and posterior stroma (30-94% depth) and endothelium (98-100% depth) were the lowest. The higher the degree of astigmatism, the higher the second densitometry peak (R = 0.277, P < .001). The densitometry values of the vertex and superior parts of the cornea were higher than those in the periphery and inferior parts, respectively (all P < .001). In the Bowman membrane, the densitometry is lowest in the inferior nasal part, while in the Descemet membrane, it is lowest in the inferior temporal part. CONCLUSION: Two densitometry peaks appeared near the Bowman membrane and Descemet membrane. For different depths, the distribution of densitometry within a layer is different. We provide a methodological reference and data basis for corneal research based on local changes in densitometry, and help understand the details of corneal structure from an optical perspective through detailed layering and zoning analysis of densitometry.

Simultaneous Determination of Montelukast Sodium and Loratadine by Eco-Friendly Densitometry and Spectrophotometric Methods.

Recently, the aim of analytical community is to reduce the usage of hazardous chemicals; so eco-friendly, rapid, selective and cost-effective methods were developed for simultaneous determination of montelukast sodium (MKT) and loratadine (LRT). The first method was based on chromatographic separation performed on precoated silica gel 60 GF254 plates with ethyl acetate-ethanol 9: 1 (v/v) as the mobile phase. The developed plates were scanned and quantified at 260 nm. The method gives linear correlation over concentration ranges of 0.3-3.6 µg/spot and 0.2-4.0 µg/spot for MKT and LRT, respectively. It was also successfully applied to analysis of both drugs in their pharmaceutical preparation and human plasma. The other methods are UV-spectrophotometric methods based on smart spectra manipulating to zero order spectrum of each drug. These methods are named response correlation (RC), a-centering and ratio derivative methods. RC and a-centering methods were dependent on the presence of an isosbestic point between the overlapped spectra of both drugs. While ratio derivative method based on manipulation of the ratio spectra of both drugs. The two drugs obey Beer-Lambert law over the concentration ranges of 3.0-30.0 µg/mL in the three spectrophotometric methods. Moreover, the greenness of the developed methods is assessed using suitable analytical Eco-Scale and Green Analytical Procedure Index.

The intra- and inter-day repeatability of corneal densitometry measurements in subjects with keratoconus and in healthy controls.

The healthy cornea is transparent, however, disease can affect its structure, rendering it more or less opaque. The ability to assess the clarity of the cornea objectively could thus be of considerable interest for keratoconus patients. It has previously been suggested that densitometry can be used to diagnose early keratoconus, and that the values of densitometry variables increase with increasing disease severity, indicating that densitometry could also be used to assess progressive keratoconus. Previous studies have only assessed the repeatability of corneal densitometry measurements on the same day, which does not reflect the clinical setting in which changes are evaluated over time. We have therefore evaluated the inter-day repeatability of densitometry measurements in both patients with keratoconus and healthy controls. Measurements in the middle layer of the 2-6 mm zone of the cornea showed the best repeatability. Although an objective measure of the corneal transparency could be interesting, the generally poor repeatability of densitometry measurements limits their use. The repeatability of corneal clarity measurements could be improved by using other approaches such as optical coherence tomography, but this remains to be investigated. Such improvements would allow the more widespread use of corneal densitometry in clinical practice.

Distribution of corneal densitometry in different grades of keratoconus.

Purpose: To evaluate the use of Scheimpflug tomography in corneal densitometry (CD) in comparing the stages of keratoconic eyes. Methods: Keratoconic (KC) corneas (stages 1-3 classified according to the topographic parameters) were examined using the Scheimpflug tomographer (Pentacam, Oculus) using the CD software. CD was measured over three different depths (anterior stromal layer [120 µm], posterior stromal layer [60 µm], and middle stromal layer between these two layers), and concentric annular zones (0.0 to 2.0, 2.0 to 6.0, 6.0 to 10.0, and 10.0 to 12.0 mm diameter area). Results: The study participants were divided into three groups: keratoconus (KC) stage 1 (KC1) with 64 participants, keratoconus stage 2 (KC2) with 29 participants, and keratoconus stage 3 (KC3) with 36 participants. Comparing CD of all three layers (anterior, central, and posterior) of the cornea over different circular annuli (0-2, 2-6, 6-10, and 10-12 mm) revealed a significant difference in the 6-10 mm annulus between all groups and in all layers (P = 0.3, 0.2, and 0.2, respectively). Area under curve (AUC) was done. It revealed that the central layer showed the highest specificity (93.8%) in comparing KC1 and KC2, whereas CD in the anterior layer between KC2 and KC3 had the highest specificity (86.2%). Conclusion: CD showed increased values in the anterior corneal layer and in the annulus 6-10 mm more than other locations in all stages of KC.

Corneal densitometry: an innovative method to quantitatively evaluate corneal changes after phacovitrectomy.

BACKGROUND: To quantitatively investigate corneal changes and the correlation between corneal densitometry (CD) and endothelial parameters after phacovitrectomy. METHODS: Thirty-eight eyes with idiopathic full-thickness macular holes (iFTMHs) and cataracts underwent phacovitrectomy. Examinations were conducted at baseline and Day 1, Day 7, Month 1, and Month 3 postoperatively. CD and central corneal thickness (CCT) were measured using Pentacam. Corneal endothelial cell density (ECD), coefficient of variation (CV), and hexagonality (HEX) were measured using specular microscopy. RESULTS: ECD and HEX significantly decreased after surgery and the change in HEX occurred prior to CV. CCT increased immediately after surgery and recovered 3 months postoperatively. CD values increased significantly 1 day after surgery and then gradually decreased. For CD in the 0-2 mm zone, it took 1 month to recover in the central and posterior layers and 3 months in the anterior and total layers. For CD in the 2-6 mm zone, the central layer recovered at Day 7, the anterior and total layers recovered at 1 month, and the posterior layer did not recover until 3 months postoperatively. The CD within all layers in the 0-2 mm zone was positively correlated with CCT. Posterior CD in the 0-2 mm zone was negatively correlated with ECD and HEX. CONCLUSIONS: CD is not only correlated with CCT, ECD, and HEX but also reflects the state of the whole cornea and each layer. CD can be an objective, rapid, and noninvasive tool that reflects corneal health and undetectable edema and monitors the process of lesion repair. TRIAL REGISTRATION: This study was registered with the Chinese Clinical Trial Registry (31/10/2021, ChiCTR2100052554).

Corneal Densitometry to Assess the Corneal Cystine Deposits in Patients With Cystinosis.

PURPOSE: The purpose of this study was to assess the suitability of corneal densitometry measurements obtained with Scheimpflug imaging in estimating the corneal changes caused by cystine deposits in the cornea in patients with cystinosis. METHODS: Scheimpflug imaging (Pentacam) was performed for 14 patients with cystinosis and 16 age-matched controls. Pentacam data were used for analysis of the corneal densitometry at different zones in the cornea for patients with cystinosis and controls. Densitometry measurements were compared with the corneal crystal scores obtained from the slitlamp images for patients with cystinosis. RESULTS: There was no statistically significant difference in keratometry measurements between the 2 groups ( P > 0.05). Corneal thickness was found to be significantly higher in the control group when compared with the cystinosis group ( P = 0.0004). The mean corneal densitometry was significantly higher in patients with cystinosis when compared with controls at most of the corneal layers and zones. The corneal densitometry readings for the right and left eyes showed moderate positive correlation with the corneal crystal score with a ceiling effect being reached at the maximum corneal crystal score of 3. CONCLUSIONS: Corneal densitometry obtained through Pentacam can be used as an objective estimate of the level of cystine crystals present in patients with cystinosis. The clinical estimate of corneal crystal score, although effective at low levels of crystal deposition, does not allow for accurate estimates of change when the level of crystal deposition is high leading to limited utility when assessing treatment effects. Hence, densitometry measurements can potentially be used to assess treatment efficacy of cystinosis treatments in clinical settings.