Aberrometría corneal en el queratocono subclínico

Objetivo: Determinar parámetros aberrométricos de la córnea para la detección del queratocono subclínico. Métodos: Se realizó un estudio observacional, analítico de corte transversal que incluyó 36 pacientes con queratocono subclínico (grupo de estudio) y 36 estudiantes con córneas aparentemente sanas (grupo control), que asistieron a la consulta de córnea del Instituto Cubano de Oftalmología Ramón Pando Ferrer, entre mayo de 2018 y junio de 2022. Se analizaron topografía y aberrometría corneal con el tomógrafo corneal Pentacam AXL. Resultados: El grupo queratocono subclínico mostró valores similares para la queratometría, asfericidad corneal, paquimetría y el valor total de desviación en comparación con el grupo normal. Hubo diferencias estadísticamente significativas en los parámetros aberrométricos, como el coma a 90º (Z3 -1), y la raíz cuadrada media de las aberraciones de alto orden, de cara anterior, posterior y total corneal, en queratocono subclínico en comparación con el grupo normal. El coma posterior a 90º presentó un área bajo la curva (0,894) mayor dentro de las aberrometrías, con un punto de corte de -0,013 μm, con sensibilidad del 86,1 % y especificidad del 88,9 %. Conclusiones: El coma posterior a 90º (parámetro aberrométrico) presenta una alta sensibilidad y especificidad para el diagnóstico de queratocono subclínico, mediante el análisis tomográfico Pentacam AXL.

Objective: To determine corneal aberrometric parameters for the detection of subclinical keratoconus. Methods: An observational, analytical, cross-sectional study was performed including 36 patients with subclinical keratoconus (study group) and 36 students with apparently healthy corneas (control group), who attended the cornea consultation at the Cuban Institute of Ophthalmology Ramón Pando Ferrer, between May 2018 and June 2022. Corneal topography and aberrometry were analyzed with the Pentacam AXL corneal tomographer. Results: The subclinical keratoconus group showed similar values for keratometry, corneal asphericity, pachymetry and total deviation value compared to the normal group. There were statistically significant differences in aberrometric parameters, such as coma at 90° (Z3-1), and root mean square of high-order anterior, posterior and total corneal aberrations in subclinical keratoconus compared to the normal group. The 90° posterior coma presented a higher area under the curve (0.894) within the aberrometries, with a cutoff point of -0.013 μm, with sensitivity of 86.1 % and specificity of 88.9 %. Conclusions: Coma posterior to 90º (aberrometric parameter) presents high sensitivity and specificity for the diagnosis of subclinical keratoconus, using Pentacam AXL tomographic analysis.

Densitometría corneal en el queratocono

Objetivo: Evaluar la densitometría corneal en pacientes con queratocono. Métodos: Se realizó un estudio observacional descriptivo de corte transversal que incluyó 90 pacientes con queratocono (grupo de estudio) y 30 estudiantes con córneas aparentemente sanas (grupo control), que asistieron a la consulta de córnea del Instituto Cubano de Oftalmología Ramón Pando Ferrer, entre mayo del 2018 y junio del 2019. Se seleccionó el ojo derecho de cada caso. Se analizaron densitometría corneal con el tomógrafo corneal Pentacam AXL. Resultados: La densitometría fue mayor en el queratocono respecto a la córnea aparentemente sana, de 0 a 2 mm, en la capa anterior, central, y posterior, respectivamente (p < 0,001). La densitometría aumentó en los 0 a 2 mm en la capa anterior en el grupo moderado y en el grupo avanzado (p < 0,001), y entre los 2-6 mm en la capa central, de 10,86 ± 0,54 en el control, en el queratocono avanzado a 12,35 ± 1,16 y en el moderado a 12,16 ± 1,45 (p < 0,001). La densitometría aumentó en el avanzado de 27,64 ± 3,81, de 22,77 ± 2,14 en el leve, y de 24,04 ± 2,83 en el moderado y en los 0-2 mm, en la capa anterior. Conclusiones: La densitometría es mayor en la córnea queratocónica respecto a la córnea aparentemente sana, además que se incrementa al aumentar la gravedad del queratocono en el área central.

Objective: To evaluate corneal densitometry in patients with keratoconus. Methods: A cross-sectional descriptive observational cross-sectional study was performed including 90 patients with keratoconus (study group) and 30 students with apparently healthy corneas (control group), who attended the cornea consultation at the Cuban Institute of Ophthalmology Ramón Pando Ferrer, between May 2018 and June 2019. The right eye of each case was selected. Corneal densitometry was analyzed with the Pentacam AXL corneal tomographer. Results: Densitometry was higher in keratoconus relative to apparently healthy cornea, from 0 to 2 mm, in the anterior, central, and posterior layer, respectively (p < 0.001). Densitometry increased in the 0 to 2 mm in the anterior layer in the moderate group and in the advanced group (p < 0.001), and between 2-6 mm in the central layer, from 10.86 ± 0.54 in the control, in the advanced keratoconus to 12.35 ± 1.16 and in the moderate to 12.16 ± 1.45 (p < 0.001). Densitometry increased in advanced from 27.64 ± 3.81, from 22.77 ± 2.14 in mild, and from 24.04 ± 2.83 in the moderate and 0-2 mm, in the anterior layer. Conclusions: Densitometry is higher in the keratoconic cornea with respect to the apparently healthy cornea, moreover it increases with increasing severity of keratoconus in the central area.

Outcomes of accelerated collagen cross linking in progressive paediatric keratoconus

Purpose: To determine the efficacy and safety of pediatric accelerated cross linking (CXL). Methods: A prospective study on progressive keratoconus (KC) cases under ?18 years of age. Sixty four eyes of thirty nine cases underwent epithelium?off accelerated CXL protocol. Visual acuity (VA), slit?lamp examination, refraction, pentacam reading of keratometry (K), corneal thickness, and thinnest location pachymetry were noted. Cases were followed up on days 1, 5, and at 1st, 3rd, 6th, and 12th?month post procedure. Results: Statistically, significant improvement of the mean aided VA, K, and mean corneal astigmatism (p < 0.0001) was noted. Mean Kmax reading reduced from 55.5 ± 5.64 (47.4–70.4) diopter (D) preoperatively to 54.41 ± 5.51 (46–68.3) D at 12 months postaccelerated CXL. Two cases had progression. Complications encountered were sterile infiltrate and persistent haze. Conclusion: Accelerated CXL is effective and efficacious in pediatric KC.

Effect of mydriatic eye drops (combined 0.8% tropicamide and 5% phenylephrine) on the measurements of corneal parameters using Pentacam

Purpose: The purpose of the study is to investigate the effects of combined 0.8% tropicamide and 5% phenylephrine on the corneal parameters using Pentacam. Methods: The study was performed on 200 eyes of 100 adult patients visiting the ophthalmology clinic for evaluation of refractive errors or cataract screening. Mydriatic drops (Tropifirin; Java, India) containing tropicamide 0.8%, phenylephrine hydrochloride 5%, and chlorbutol 0.5% (as a preservative) were instilled into the eyes of the patients three times every 10 minutes. The Pentacam was repeated after 30 minutes. The measurement data of various corneal parameters from different Pentacam displays (keratometry, pachymetry, densitometry, and Zernike analysis) was manually compiled on an Excel spreadsheet and analyzed using Statistical Package for the Social Sciences (SPSS) 20 software. Results: Analysis of Pentacam refractive maps revealed a statistically significant increase (P < 0.05) in the values of radius peripheral (cornea front), pupil center Pachymetry, pachymetry apex, thinnest location Pachymetry, and cornea volume. However, pupil dilation did not affect the Q?value (asphericity). Analysis of the densitometry values revealed significant increase in all zones. Aberrations maps revealed statistically significant increase in the value of spherical aberration after the induction of mydriasis, but the values of Trefoil 0º, Trefoil 30º, Koma 90º, and Koma 0º were not affected significantly. We did not observe any untoward effect of the drug, except transient blurring of vision. Conclusion: The current study showed that routine mydriasis in the eye clinics leads to a significant increase in various corneal parameters including corneal pachymetry, cornea densitometry, and spherical aberration as measured by Pentacam, which can influence the decision?making in the management of various corneal diseases. The ophthalmologists should be aware of these issues and make adjustments in their surgical planning accordingly

Determination of the repeatability of corneal densitometry as measured with a Scheimpflug camera device in refractive surgery candidates

Purpose: Corneal densitometry analysis provides an objective measurement of corneal transparency in patients undergoing photorefractive keratectomy (PRK). To date, no study that focuses on determining the reliability and smallest real difference (SRD), specifically in PRK candidates, has been published. Methods: The study was conducted at Clínica de Oftalmología Sandiego, Medellín, Colombia. This was a prospective and analytical study. Refractive surgery candidates underwent Pentacam measurements twice with five minutes of difference. Repeatability of measurements was evaluated for every area using Wilcoxon signed?rank test, Spearman’s rank?order correlation, and the intraclass correlation coefficient, followed by a within?subjects factor (Sw) finishing with a determination of the SRD for all areas. Bland–Altman plots were created and analyzed. Results: A total of 110 eyes were included. The mean total densitometry was 18.67 ± 1.56 grayscale units (GSU) and 18.65 ± 1.49 GSU for the first and second measurements, respectively. Wilcoxon was non?significant (P > 0.05) while the intraclass correlation coefficient demonstrated an excellent agreement. SRD ranged from 0.21 GSU (posterior × 6–10 mm) to 1.79 GSU (total × 10–12 mm). Anterior depths and 10–12 mm annulus had consistently more variability and greater (worse) SRD. The 10–12 mm annulus showed great dispersion on the Bland–Altman plots. Conclusion: Corneal densitometry has an excellent repeatability in refractive surgery candidates for areas below 10 mm. Any densitometry change ?1.0 GSU in areas under 10 mm should be considered as well above measurement noise and corresponding to a real change in measured parameters. The 10–12 mm area does not seem to be reliable enough in refractive surgery candidates to warrant surveillance after corneal?based surgery

Comparative study of corneal thickness and thinnest point position of keratoconus measured by Pentacam HR and RTVue OCT / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the difference, correlation, and consistency of corneal thickness and the thinnest point position detected by Pentacam HR corneal topography map and RTVue optical coherence tomography(OCT)in patients with keratoconus.METHODS: Cross-sectional comparative study. The corneal curvature map, corneal thickness map, thinnest point position, and thinnest point thickness were detected by Pentacam HR and RTVue OCT. Paired sample t-test was used for data consistent with normal distribution, and paired sample rank sum test was used for data inconsistent with normal distribution. Spearman correlation analysis and Bland-Altman analysis were used for the correlation and consistency of the two measurement methods.RESULTS: A total of 63 patients(105 eyes)with keratoconus were included in this study, including 49 males(77.8%)and 14 females(22.2%), aged 22.24±6.19 years; among them, relevant data of Pentacam HR topographic map: Km was 47.85±4.73D and Kmax was 55.43±8.72D. In measuring central corneal thickness and the thinnest point thickness of keratoconus, the Pentacam HR was 4.70μm and 19.46μm thicker than the mean value measured by RTVue OCT(P&#x003C;0.05). There was no significant difference between the horizontal and vertical coordinates of the thinnest points measured by the two devices(P&#x003E;0.05). The central corneal thickness and the thinnest point thickness measured by the two devices were highly correlated, the horizontal coordinate of the thinnest point was moderately correlated, and the vertical coordinate of the thinnest point was weakly correlated. Bland-Altman analysis showed that the central corneal thickness, the thinnest point thickness, the horizontal coordinate of the thinnest point, and the vertical coordinate of the thinnest point were 95.2%(100/105)and 93.3%(98/105), 95.2%(100/105), 95.2%(100/105)respectively, which were within the 95% consistency limit, while the consistency ranges were -36.00～+26.62μm, -42.27～+3.36μm, -0.80～+0.84mm, and -1.95～+1.06mm, respectively.CONCLUSION: In keratoconus, the central corneal thickness and the thinnest point thickness measured by Pentacam HR were higher than those measured by RTVue OCT. It is not recommended that the central corneal thickness and the thinnest point thickness measured by the two instruments be interchangeable in clinical use because of the wide range of consistency between the two instruments' results. The position of the thinnest corneal point measured by the two instruments is similar and consistent, so it could be considered to replace the measured values of the two instruments in clinical use.

Clinical study on the diagnosis of early keratoconus based on ocular morphological parameters with different corneal diameters / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the diagnostic value of ocular morphological parameters under different corneal diameters for early keratoconus.METHODS: A retrospective case-control study. A total of 201 patients(201 eyes)who were treated in our hospital from January 2019 to March 2022 were included. They were divided into 135 cases(135 eyes)in the control group(patients with history of refractive error)and 66 cases(66 eyes)in the subclinical keratoconus group. The Pentacam anterior segment analyzer was used to determine the horizontal central curvature of corneal posterior surface(Kf), posterior vertical central curvature of corneal posterior surface(Ks), average curvature of corneal posterior surface(Km), Posterior I-S ratio, corneal posterior surface height after the thinnest point(PE at the thinnest point), maximum posterior elevation from best fit sphere(MPE from BFS), maximum posterior elevation from best fit toric ellipsoid(MPE from BFTE), posterior asphericity asymmetry index(AAI), thinnest point thickness of the cornea(TCT), central corneal thickness(CCT), depressed corneal thickness(DCT), pachymetric progression index average(PPIavg), Ambrósio relational thickness maximum(ARTmax)and Belin D value. The differences of each parameter between the two groups were analyzed. Receiver operating characteristic(ROC)curves were analyzed to determine the best diagnosis point. The control group was further divided into groups according to the corneal diameter: corneal diameter ≤11.0mm, 11.1mm≤ corneal diameter ≤11.5mm, 11.6mm≤ corneal diameter ≤12.0mm, corneal diameter ≥12.1mm. The differences of each parameter among these groups were compared. Pearson correlation analysis was used to analyze the correlation between corneal diameter and other parameters.RESULTS: There were significant differences in posterior I-S ratio, PE at the thinnest point, MPE from BFS, MPE from BFTE, posterior AAI, TCT, DCT, PPIavg, ARTmax, Belin D value between the subclinical keratoconus group and the control group(P&#x0026;#x003C;0.05). Sensitive index of Pentacam to diagnosis subclinical keratoconus were Belin D value, posterior I-S ratio, PPIavg, posterior AAI and MPE from BFTE(AUC≥0.9). In the control group, there was no significant difference in posterior I-S ratio, MPE from BFTE, posterior AAI, TCT, CCT, and DCT among different corneal diameter groups (P&#x0026;#x003E;0.05), and there was no significant correlation with corneal diameter(all P&#x0026;#x003E;0.05).CONCLUSION: The Belin D value, posterior I-S ratio, PPIavg, posterior AAI, MPE from BFTE obtained by Pentacam are sensitive indicators for the diagnosis of early keratoconus, among which posterior I-S ratio, posterior AAI, MPE from BFTE are less affected by corneal diameter. They play an important role in the early diagnosis of keratoconus under different corneal diameters.

The Pentacam® AXL Wave provides a reliable wavefront-based objective refraction when compared to manifest subjective refraction: A prospective study

Purpose: Accurate refraction is arguably the most important parameter for a successful laser vision correction surgery and is based on a combination of manifest and cycloplegic refraction. Wavefront?based objective refraction may be useful in the evaluation of patients. So far, the reliability of objective refraction as measured using the Pentacam® AXL Wave has not been published in the literature. Methods: This was a prospective study including a total of 168 eyes belonging to 84 young non?presbyopic patients evaluated for refractive surgery. Pentacam® AXL Wave full sequence was taken for all patients. Then, a clinician who was unaware of the objective refraction results performed a full physical examination, including manifest refraction starting from an autorefractometer value. All refraction values were transferred to astigmatic power vectors as per the Thibos method. Reliability of the different vectors and a unifying blur value were compared using Spearman correlation, Bland–Altman plot, and intraclass correlation coefficient. Results: The mean age was 28.8 ± 5.4 years, with a female preponderance (60.7%). The correlation between both eyes was high. The difference in M vector between subjective and objective refraction was 0.16 D, while the difference was 0.04 and 0.01 D for the J0 and J45 vectors, respectively. Paired samples Student t was non?significant for all comparisons. Spearman rho correlations were high (0.666–0.924, all P < 0.001). Intraclass correlation coefficients were also high (0.890–0.966). Bland–Altman plots did not demonstrate any systematic errors. Conclusion: Wavefront?based refractive refraction obtained using the Pentacam® AXL Wave is highly agreeable and correlated with measurements obtained by manifest subjective refraction.

Impact of tear optics on the repeatability of Pentacam AXL wave and iTrace in measuring anterior segment parameters and aberrations

Purpose: To assess impact of tear optics on repeatability of a Scheimpflug device with a Hartmann Shack aberrometer and a ray tracing aberrometer. Methods: One hundred healthy and 100 postrefractive surgery eyes underwent dry eye evaluation including Schirmer抯 test and tear film break?up time (TBUT). They underwent optical quality analyzer (OQAS, Visio metrics S.L, Terrassa, Spain) to assess objective scatter index (OSI), three scans each on Pentacam AXL wave (OCULUS Optikgerate Gmbh, Wetzlar, Germany), iTrace (Tracey� Technologies, Texas, USA) for flat, steep keratometry, thinnest corneal thickness, root mean square higher?order aberrations (RMS HOA), RMS lower?order aberrations (LOA), spherical aberrations, RMS COMA. Repeatability of Pentacam AXL wave and iTrace in healthy and postrefractive eyes (OSI >1 vs OSI <1) was studied using within?subject standard deviation (Sw) test杛etest repeatability (TRT), coefficient of variation (COV). Results: OSI showed an inverse association with TBUT (P < 0.001). All measurements with Pentacam AXL wave with OSI < 1 had excellent repeatability, intraclass correlation coefficient (ICC) ranging from 0.88 for HOA, to 0.92 for LOA. The Sw, TRT, and COV of all aberration measurements were significantly lower (better) than those of iTrace. In eyes with OSI ?1, the repeatability with Pentacam AXL wave dropped with ICC ranging from 0.77 for HOA, to 0.84 for LOA with lower Sw, TRT, and COV of all aberration measurements as compared to iTrace. Maximum variation was seen with HOA and minimum with LOA. Conclusion: Tear optics affected repeatability of Pentacam wave and iTrace. Pentacam wave had better repeatability in eyes with a poor tear film as compared to iTrace. Thus, the tear film can impact repeatability of an instrument and it is important to assess the tear film prior to imaging patients, which can change the way we interpret and image these patients.

Assessment of the postoperative effect of corneal cross-linking on keratoconus using the ABCD grading system

Purpose: To monitor the changes in the ABCD grading system during a one?year follow?up after a corneal cross?linking (CXL) procedure. Methods: This prospective study included 30 eyes of 25 patients with keratoconus, who received the CXL treatment. The patients with a history of ocular trauma or surgery and other corneal pathology were excluded from the study. The patients were examined at the baseline visit and followed up at 3, 6, and 12 months after the CXL. All the patients underwent a standard CXL procedure with visual acuity and Scheimpflug tomography testing at each visit. The corneal parameters and ABCD grading were monitored throughout the follow?up period. Results: There were no significant changes of parameter A and anterior radius curvature (ARC) in the ABCD grading system. Parameters B and D showed progression postoperatively, with an improvement of parameter D on the final visit. Parameter C showed a statistically significant increase at all three post?CXL visits, but a constant gradual decrease in the value over time. Conclusion: The ABCD grading system can be very useful in monitoring the progression of keratoconus (KC), but it can also help in monitoring the efficacy of corneal cross?linking. The anterior surface parameters in the ABCD grading system did not show progression in the post?CXL period, and parameters C and D showed improvement and stability a year after the procedure.

Changes of corneal astigmatism and tear film stability in patients with cataract and pterygium combined operation / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the changes and clinical significance of corneal parameters and tear film stability after cataract combined with pterygium surgery. <p>METHODS: The clinical data of 80 patients with cataract and pterygium admitted to our hospital from January to December 2020 were retrospectively studied. All patients underwent pterygium excision + phacoemulsification + intraocular lens implantation + limbal stem cell transplantation. The changes of visual acuity, corneal Pentacam parameters, corneal astigmatism, corneal curvature and tear film stability before and after operation were compared, and the degree deviation of intraocular lens(IOL)was calculated.<p>RESULTS: At 3mo after operation, the average corneal refractive index and average corneal refractive index of the patients in this group were significantly higher than those before operation. The index of surface variance(ISV)of corneal surface and astigmatism of anterior corneal surface were significantly lower than those before operation, and the indexes of tear film stability were significantly improved compared with those before operation(all <i>P</i><0.01). At 6mo after operation, the visual acuity of the patients in this group was significantly improved compared with that before operation, and the corneal astigmatism was significantly decreased compared with that before operation, but the corneal curvature was significantly higher than that before operation(all <i>P</i><0.001). The IOL degree deviation of the patients in this group was -5.5 - +3.5D.<p>CONCLUSION: Cataract combined with pterygium surgery can effectively improve the visual acuity of patients and improve the stability of tear film, but there may be corneal astigmatism. Therefore, the contralateral corneal refractive power should be used to calculate the IOL degree after pterygium excision. When the corneal refractive state is stable, cataract phacoemulsification is performed to ensure its prognosis.

Comparsion of corneal astigmatism measurement among iTrace, IOL Master 700 and Pentacam HR in cataract eyes / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the difference and consistency among iTrace, IOL Master 700 and Pentacam HR in measuring corneal astigmatism before cataract surgery.<p>METHODS: Across-sectional study. From May 2020 to May 2021, a total of 149 cataract patients(181 eyes)were collected in our hospital. Presurgery, steep keratometry(Ks), flat keratometry(Kf), mean keratometry(Km), astigmatism magnitude(Cyl), and steep astigmatic axis values measured by the three instruments of the iTrace, IOL Master 700 and the Pentacam HR. The difference and consistency of the measurement indexes of the three instruments were analyzed.<p>RESULTS: Statistical differences existed in Ks, Kf, Km among the three instruments(<i>F</i>=4.912, 3.514, 4.873, all <i>P</i><0.05)and there was no difference in Cyl and Axis(<i>F</i>=0.523, 0.128, all <i>P</i>>0.05). Bland-Altman analysis showed the outcomes revealed that the Ks and Kf measured by iTrace and the other two instruments have poor consistency, and the consistency of Cyl and Axis was good. But the difference of Axis is not clinically acceptable. There were no statistically differences between the iTrace and the other two devices among the low astigmatism(50 eyes), moderate astigmatism(34 eyes)and high astigmatism(18 eyes)groups(all <i>P</i>>0.05). <p>CONCLUSION: In the preoperative measurement of cataract patients except for the good consistency of astigmatism, the iTrace, IOL Master 700 and Pentacam HR showed different Ks and Kf, and the Axis difference exceeded the clinically acceptable range, especially in the highly astigmatism group. The measurement of corneal astigmatism before cataract surgery should be evaluated by multiple measurement methods and make comprehensive planning for the surgical plan.

Study on the relationship between astigmatism and keratoconus by using Pentacam anterior segment analyzer / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To study the relationship between astigmatism and keratoconus by using Pentacam anterior segment analyzer.METHODS:Totally 88 patients(93 eyes)with early keratoconus were divided into clinical keratoconus group(43 cases, 46 eyes)and subclinical keratoconus group(45 cases, 47 eyes)according to related standards. Meanwhile, 40 patients(41 eyes)with history of myopia and astigmatism(astigmatism ≥2.0D)were recorded as the control group. The keratoconus index(KI), corneal index of surface variance(ISV)and index of vertical asymmetry(IVA)were determined using Pentacam anterior segment analyzer, and their diagnostic value for keratoconus was analyzed.RESULTS:The parameters of Pentacam anterior segment analyzer were different among the three groups(<i>P</i><0.05). Rmin was the highest, and other parameters were the lowest in the control group. Rmin was lower, and other parameters were higher in the clinical keratoconus group than in the subclinical keratoconus group(<i>P</i><0.05). The area under curve(AUC)values of ISV, KI, IVA, index of highest decentration(IHD), aberration coefficient(ABR), corneal anterior surface maximum keratometry(Kmax), posterior corneal surface elevation(PE), minimun radius of curvature(Rmin)and corneal anterior surface elevation(AE)in the diagnosis of clinical keratoconus were 1, 1, 1, 1, 0.950, 0.919, 0.951, 1 and 0.992, with good sensitivity and specificity. IVA, Rmin, AE, and PE had better sensitivity and specificity in the diagnosis of subclinical keratoconus. The AUC values were 0.927, 0.923, 0.954, and 0.947, respectively.CONCLUSION:Pentacam anterior segment analysis system has great value in early diagnosis of keratoconus.

Mediciones biométricas en pacientes miopes con cirugía fotoablativa previa / Biometric measurements in myopic patients with previous photoablative surgery

Objetivo: Comparar las mediciones biométricas realizadas con el IOL Master 700 y el Pentacam AXL en pacientes miopes con cirugía fotoablativa previa. Métodos: Se realizó un estudio transversal en 103 ojos de 103 pacientes miopes con cirugía fotoablativa previa, atendidos en el período de enero 2019 a enero 2020, en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer". Las variables estudiadas fueron: edad, sexo, equivalente esférico y características biométricas posoperatorias (longitud axial, profundidad de la cámara anterior y queratometrías), así como su relación, aportadas automáticamente por el IOL master 700 y el pentacam AXL para evitar los factores dependientes del operador, tres meses después de la cirugía. El análisis estadístico se realizó con la prueba t para datos pareados, utilizando una significación del 95 por ciento. Resultados: La edad promedio fue de 25,72 ± 4,26 años. Se analizaron 53 ojos derechos y 50 izquierdos, todos tratados con láser de superficie. El equivalente esférico medio fue de -0,06 ± 0,34 dioptrías y el tiempo entre la cirugía y los exámenes fue de 6,32 ± 3,56 meses. No hubo diferencia estadísticamente significativa (p > 0,05) entre la longitud axial y la profundidad de la cámara anterior; mientras que sí la hubo (p < 0,01) con las queratometrías obtenidas con el IOL Master 700, en comparación con los del pentacam AXL. Conclusión: En pacientes miopes con cirugía fotoablativa previa, el IOL Master 700 y el pentacam AXL proveen mediciones biométricas similares, como la longitud axial y la profundidad de la cámara anterior, no así con la queratometría, la cual es diferente(AU)

Objective: Compare the biometric measurements taken with IOL Master 700 and Pentacam AXL in myopic patients with previous photoablative surgery. Methods: A cross-sectional study was conducted of 103 eyes of 103 myopic patients undergoing photoablative surgery at Ramón Pando Ferrer Cuban Institute of Ophthalmology from January 2019 to January 2020. The variables analyzed were age, sex, spherical equivalent and preoperative biometric characteristics (axial length, anterior chamber depth and keratometries) and the relationship to one another, automatically supplied by IOL Master 700 and Pentacam AXL to avoid operator-dependent factors. The analysis was performed three months after surgery. Statistical analysis was based on the paired Student's t-test with a significance level of 95 percent. Results: Mean age was 25.72 ± 4.26 years. Fifty-three right eyes and 50 left eyes were studied, all of them treated with surface laser. Mean spherical equivalent was -0.06 ± 0.34 diopters; the time elapsed between surgery and the tests was 6.32 ± 3.56 months. No statistically significant differences (p > 0.05) were found between axial length and anterior chamber depth, but statistically significant differences (p < 0.01) were observed between the keratometries obtained with IOL Master 700 and Pentacam AXL. Conclusion: IOL Master 700 and Pentacam AXL provide similar biometric measurements for axial length and anterior chamber depth in myopic patients with previous photoablative surgery, but keratometric measurements are different(AU)

Comparación entre las mediciones biométricas del IOL Master 500 y el Pentacam AXL en la biometría ocular / Comparison of biometric measurements taken with IOL Master 500 and Pentacam AXL for ocular biometry

Objetivo: Comparar las mediciones biométricas realizadas con el IOL Master 500 y el Pentacam AXL. Métodos: Se realizó un estudio transversal en 99 ojos de 99 pacientes miopes con criterio de cirugía fotoablativa, atendidos en el período de enero del año 2019 a enero de 2020, en el Servicio de Cirugía Refractiva del Instituto Cubano de Oftalmología "Ramón Pando Ferrer". Las variables estudiadas fueron edad, sexo, equivalente esférico y características biométricas preoperatorias (longitud axial, profundidad de la cámara anterior y queratometrías), así como su relación, aportadas automáticamente por el IOL Master 500 y el Pentacam AXL para evitar los factores dependientes del operador. El análisis estadístico se realizó con la Prueba t para datos pareados, utilizando una significación del 95 por ciento. Una diferencia con un valor de p < 0,05 fue considerado estadísticamente significativo. Resultados: El 60,61 por ciento de los pacientes eran de sexo femenino y el 39,39 por ciento del masculino, con una edad promedio de 25,67 ± 4,30 años. Se analizaron 51 ojos derechos y 48 izquierdos. El equivalente esférico medio fue de -3,30 ± 1,53 dioptrías. No hubo diferencia estadísticamente significativa entre los valores biométricos (longitud axial, profundidad de la cámara anterior y queratometrías) obtenidos con el IOL Master 500, en comparación con los del Pentacam-AXL (p > 0,05). Conclusión: Las mediciones biométricas (longitud axial, profundidad de la cámara anterior y queratometrías) obtenidas con el IOL Master 500 y el Pentacam-AXL son similares(AU)

Objective: Compare biometric measurements taken with IOL Master 500 and Pentacam AXL. Methods: A cross-sectional study was conducted of 99 eyes of 99 myopic patients with indication of photoablative surgery attending the Refractive Surgery Service at Ramón Pando Ferrer Cuban Institute of Ophthalmology from January 2019 to January 2020. The variables analyzed were age, sex, spherical equivalent and preoperative biometric characteristics (axial length, anterior chamber depth and keratometries) and the relationship to one another, automatically supplied by IOL Master 500 and Pentacam AXL to avoid operator-dependent factors. Statistical analysis was based on the paired T-test with a significance level of 95%. A difference with a p-value < 0.05 was considered to be statistically significant. Results: Of the patients studied, 60.61 percent were female and 39.39 percent were male; mean age was 25.67± 4.30 years. A total 51 right eyes and 48 left eyes were analyzed. Mean spherical equivalent was -3.30 ± 1.53 diopters. No statistically significant difference was found between the biometric values (axial length, anterior chamber depth and keratometries) obtained with IOL Master 500 versus Pentacam AXL (p > 0.05). Conclusion: Similar biometric measurements (axial length, anterior chamber depth and keratometries) are obtained with IOL Master 500 and Pentacam AXL(AU)

Comparison of three instruments for measuring corneal biological parameters before cataract surgery / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To compare the differences of corneal curvature and astigmatism measured by Pentacam, IOL Master and iTrace of cataract patients.<p>METHODS:In this prospective clinical trial,68 cataract patients(82 eyes)received treatment at the ophthalmology department of our hospital. In the treatment process, used the IOL Master, Pentacam and iTrace to measure the patient's corneal curvature(K1, K2, Km)and astigmatism(J0, J45). The difference, correlation and consistence among three instruments were analysed. <p>RESULTS: Differences analysis showed that in the measurement of K1, K2, Km, there was no difference among Pentacam, IOL Master and iTrace(<i>P</i>>0.05). Pearson correlation analysis showed that K1, K2, Km were highly correlated among three instruments(|<i>r</i>|>0.5, <i>P</i><0.01). J0, J45 were moderately correlated between IOL Master and Pentacam, so as IOL Master and iTrace(0.3<|<i>r</i>|<0.5, <i>P</i><0.01). J0, J45 were weakly correlated between Pentacam and iTrace(0.1<|<i>r</i>|<0.3, <i>P</i><0.05). The Bland-Altman showed that the corneal curvature and astigmatism vectors examined by these three devices had non-comparable results.<p>CONCLUSION: K1, K2, Km, J0, J45 were correlated among the three devices, but the three devices all cannot directly interchanged, targeted selection is required for the measuring the corneal curvature and astigmatism by these three different instruments in the actual clinical process.

Analysis of dynamic changes of posterior corneal power and astigmatism after cataract surgery based on Pentacam system / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate dynamic changes of posterior corneal power and astigmatism after cataract surgery based on Pentacam three-dimensional anterior eye segment analyzer.<p>METHODS: Totally 96 elderly patients(116 eyes)with cataract underwent phacoemulsification combined with intraocular lens implantation in our hospital from January 2019 to January 2020 were selected. Parameters including anterior corneal power, posterior corneal power, flat keratometry, steep keratometry, mean keratometry, anterior corneal astigmatism, posterior corneal astigmatism, and total corneal astigmatism were obtained using Pentacam three-dimensional anterior eye segment analyzer system at postoperative 1wk, 1mo and 3mo. Spearan correlation analysis was performed on the anterior segment. <p>RESULTS: The anterior corneal power(flat keratometry, steep keratometry, mean keratometry)was lower at postoperative 1wk than that before operation, and began to return to the preoperative level at postoperative 1mo and 3mo. The posterior corneal power and total corneal power(flat keratometry, steep keratometry, mean keratometry)were higher at postoperative 1wk than before operation, and began to stabilize at postoperative 3mo. The anterior corneal astigmatism, posterior corneal astigmatism, and total corneal astigmatism were also higher at postoperative 1wk than before operation, and began to decrease and stabilize at postoperative 3mo. The anterior corneal power was significantly positively correlated with total corneal power; The posterior corneal power was significantly negatively correlated with the total corneal power, and was significantly positively correlated with its absolute value(<i>P</i><0.05). The total corneal astigmatism before operation and at postoperative 1wk and 3mo was significantly positively correlated with anterior corneal astigmatism at corresponding time points(<i>P</i><0.01), while showed no significant correlation with posterior corneal astigmatism.<p>CONCLUSION: Changes of posterior corneal power and astigmatism can be observed with 3mo of cataract surgery, and Pentacam three-dimensional anterior eye segment analyzer system can accurately assess the dynamic changes of anterior and posterior corneal power and astigmatism before and after operation, which is of great clinical value.

Analysis of clinical efficacy of Toric intraocular lens guided by corneal topography / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To investigate the function of Pentacam in accurately selecting the model and axial position of Toric artificial lens. <p>METHODS: Totally 53 eyes of 46 cataract patients who were scheduled to receive phacoemulsification from January 2018 to December 2018 were selected in our hospital. Before the operation, corneal astigmatism was greater than 1.0D according to the examination results by AL-Scan and automatic corneal curvature instrument, and Pentacam was used to evaluate the corneal astigmatism to guide the accurate selection of Toric IOL model and the axial position to be implanted. Surgery was done by the same doctor. After operation, the patients were traced and visited for 3mo to collect the uncorrected visual acuity(UCVA), the best corrected visual acuity(BCVA), the whole-eye astigmatism, the corneal curvature and target induced astigmatism(TIA)before and after the operation as well as the postoperative astigmatism, the rate not relying on the glasses, visual quality assessment and so on. <p>RESULTS: There was no obvious change on patients' corneal astigmatism before and after the operation. The whole-eye astigmatism was reduced and UCVA and BCVA were obviously improved. The difference was statistically meaningful(<i>P</i><0.05). The postoperative residual astigmatism and TIA were statistically tested, and the results showed no statistical significance(<i>P</i>>0.05). The rate of distant vision defecation and visual quality were significantly improved. <p>CONCLUSION: Pentacam can evaluate the corneal astigmatism more comprehensively and accurately, which is helpful to guide the accurate selection of Toric artificial lens model, and to improve the postoperative expected effect.

Diagnostic value of Pentacam anterior segment analyzer examination parameters on early keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To analyze the diagnostic value of Pentacam anterior segment analyzer examination parameters on early keratoconus.<p>METHODS: Retrospective control study. Totally 100 patients(124 eyes)with keratoconus who were treated in the hospital between January 2019 and January 2020 were selected as study group. According to the severity of Amsler-Krumeich classification, patients with keratoconus were divided into mild group(51 eyes), moderate group(43 eyes)and severe group(30 eyes), and another 30 normal people with past history of myopia and astigmatism(30 eyes)were selected as control group. The Pentacam anterior segment analyzer parameters \〖horizontal central curvature of 3mm diameter range(K1), vertical central curvature of 3mm diameter range(K2), maximum refractive power of corneal anterior surface(Kmax), corneal astigmatism(Cyl), corneal thickness at the thinnest(thinnest local), ROC curve was used to analyze the sensitive indicators in the diagnosis of early keratoconus.<p>RESULTS:The K1, K2, Kmax, Cyl, ISV, IVA, KI and ACD in study group were significantly higher than those in control group(<i>P</i><0.05)while the thinnest local and ACV were significantly lower than those in control group(<i>P</i><0.05). There were statistically significant differences in the K1, K2, Kmax, Cyl, thinnest local, ISV, IVA, KI, ACV and ACD among patients with different degrees of keratoconus(<i>P</i><0.05), and the K1, K2, Kmax, Cyl, ISV, IVA, KI and ACD in moderate group and severe group were significantly higher than those in mild group(<i>P</i><0.05)while the thinnest local and ACV were significantly lower than those in mild group(<i>P</i><0.05), and there were significant differences in the parameters between moderate group and severe group(<i>P</i><0.05). ROC diagnostic curve results showed that Kmax, thinnest local, ISV, IVA and KI were sensitive indicators for diagnosing keratoconus(AUC>0.85), of which ISV had the highest diagnostic value.<p>CONCLUSION: Pentacam anterior segment analyzer can effectively measure the keratoconus parameters. There are differences in the parameters among patients with different degrees of keratoconus. Kmax, thinnest local, ISV, IVA and KI are sensitive indicators for diagnosing early keratoconus, and Pentacam anterior segment analyzer examination parameters have a higher diagnostic value on early keratoconus.

Analysis of corneal biological parameters measured by IOL Master 700 and Pentacam in patients with cataract of different ages / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To compare the difference, correlation and consistency of corneal biological parameters measured by IOL Master 700 and Pentacam before cataract extraction and intraocular lens implantation in different age groups.<p>METHODS: Cross-sectional study. A total of 87 cataract patients(162 eyes)in Weifang Eye Hospital from February to September 2020 were collected, including 44 males(80 eyes)and 43 females(82 eyes)(age 61.2±9.87 years). The patients were divided into four groups: group A \〖17 cases(32 eyes), 40-50 years old\〗, group B \〖25 cases(47 eyes), 51-60 years old\〗, group C \〖28 cases(53 eyes), 61-70 years old\〗, and group D \〖17 cases(30 eyes), 71-80 years old\〗. The preoperative corneal biological parameters of cataract patients were measured by IOL Master 700 and Pentacam, and the flat axis corneal curvature(K1), steep axis corneal curvature(K2), mean corneal curvature(Km), corneal astigmatism, anterior chamber depth(ACD)and central corneal thickness(CCT)were recorded. The difference and correlation of measurement results between two kinds of biometric instruments in different age groups were analyzed. <p>RESULTS: Except for the corneal astigmatism in group C and K1 and corneal astigmatism in group D, there were significant differences between the two instruments(<i>t</i>=2.746, -2.582, 2.637, all <i>P</i><0.05), but there was no significant difference in other parameters among the four groups. Pearson correlation analysis showed that there was a good correlation between the two instruments in measuring the parameters of the four groups of patients. The results of Bland-Altman analysis showed that there was a good consistency between IOL Master 700 and Pentacam in measuring K1, K2, Km, corneal astigmatism, ACD and CCT in the four groups.<p>CONCLUSION:There was no significant difference between IOL Master 700 and Pentacam in the measurement of corneal biological parameters in cataract patients aged 40-60 years, but there was significant difference in astigmatism between 61-70 years old, astigmatism and K1 value in 71-80 years old patients. Pearson correlation analysis showed that there was a good correlation between the two instruments. Generally speaking, the consistency of the two kinds of examination equipment is good, and the corneal astigmatism and corneal curvature should be selected by comprehensive analysis of the data.