Repeatability assessment of anterior segment measurements in myopic patients using an anterior segment OCT with placido corneal topography and agreement with a swept-source OCT.

BACKGROUND: The precision of anterior segment biometric measurements in eyes has become increasingly important in refractive surgery. The purpose of this study is to assess the repeatability of the automatic measurements provided by a new spectral-domain optical coherence tomograph (SD-OCT)/Placido topographer (MS-39, CSO) and its agreement with a swept-source OCT (SS-OCT) biometer (CASIA SS-1000, Tomey) in patients with myopia. METHODS: The right eye of 235 subjects was scanned 3 times with both devices. The evaluated parameters included central corneal radius of the steep meridian, central corneal radius of the flat meridian, mean central corneal radius, thinnest corneal thickness, central corneal thickness, anterior chamber depth, corneal volume and diameter. The intraobserver repeatability of the MS-39 measurements was calculated using intraclass correlation coefficient (ICC), within subject standard deviation, coefficient of repeatability, coefficient of variation and repeated-measures analysis of variance of the 3 repeated measurements. The agreement between the two devices was evaluated by 95% limits of agreement (LoA). RESULTS: The majority of the parameters acquired from MS-39 showed high repeatability. The repeatability of corneal diameter was slightly lower than the other measurements, although the ICC remained high. Agreement with the CASIA SS-1000 was good, indicated by the Bland-Altman plots with narrow 95% LoA values for all parameters assessed. CONCLUSIONS: The high repeatability of automatic measurements by the new device supports its clinical application in eyes with myopia, and the good agreement between the two devices indicates they could be used interchangeably for the parameters evaluated.

The effects of pharmacological accommodation and cycloplegia on axial length and choroidal thickness / Efeitos da acomodação farmacológica e da cicloplegia no comprimento axial e na espessura da coroide

ABSTRACT Purpose: To investigate the effects of pharmacological accommodation and cycloplegia on ocular measurements. Methods: Thirty-three healthy subjects [mean (±SD) age, 32.97 (±5.21) years] volunteered to participate in the study. Measurement of the axial length, macular and choroidal thickness, refractive error, and corneal topography, as well as anterior segment imaging, were performed. After these procedures, pharmacological accommodation was induced by applying pilocarpine eye drops (pilocarpine hydrochloride 2%), and the measurements were repeated. The measurements were repeated again after full cycloplegia was induced using cyclopentolate eye drops (cyclopentolate hydrochloride 1%). The correlations between the measurements were evaluated. Results: A significant increase in subfoveal choroidal thickness after applying 2% pilocarpine was identified (without the drops, 319.36 ± 90.08 µm; with pilocarpine instillation, 341.60 ± 99.19 µm; with cyclopentolate instillation, 318.36 ± 103.0 µm; p<0.001). A significant increase in the axial length was also detected (without the drops, 23.26 ± 0.83 mm; with pilocarpine instillation, 23.29 ± 0.84 mm; with cyclopentolate instillation, 23.27 ± 0.84 mm; p=0.003). Comparing pharmacological accommodation and cycloplegia revealed a significant difference in central macular thickness (with pilocarpine instillation, 262.27 ± 19.34 µm; with cyclopentolate instillation, 265.93 ± 17.91 µm; p=0.016). Pilocarpine-related miosis (p<0.001) and myopic shift (p<0.001) were more severe in blue eyes vs. brown eyes. Conclusion: Pharmacological accommodation may change ocular measurements, such as choroidal thickness and axial length. This condition should be considered when performing ocular measurements, such as intraocular lens power calculations.(AU)

RESUMO Objetivo: Investigar os efeitos da acomodação farmacológica e da cicloplegia nas medições oculares. Métodos: participaram do estudo 33 voluntários saudáveis (média de idade [± DP], 32,97 anos [± 5,21 anos]). Foram medidos o comprimento axial, a espessura macular e coroidal e o erro refrativo, bem como realizados exames de imagem da topografia corneana e do segmento anterior. Em seguida, foi induzida a acomodação farmacológica aplicando-se colírio de pilocarpina (cloridrato de pilocarpina a 2%) e as medições foram repetidas nos participantes. As mesmas medições foram repetidas depois de induzir a cicloplegia completa com colírio de ciclopentolato (cloridrato de ciclopentolato a 1%) e foram avaliadas as correlações entre as medidas. Resultados: Identificou-se aumento significativo da espessura coroidal subfoveal com o uso da pilocarpina a 2% (sem colírio, 319,36 ± 90,08 µm; com a instilação de pilocarpina, 341,60 ± 99,19 µm; com a instilação de ciclopentolato, 318,36 ± 103,0 µm; p<0,001). Detectou-se também aumento significativo do comprimento axial (sem colírio, 23,26 ± 0,83 mm; com a instilação de pilocarpina, 23,29 ± 0,84 mm; com a instilação de ciclopentolato, 23,27 ± 0,84 mm; p=0,003). Ao se comparar a acomodação farmacológica e a cicloplegia, houve diferença significativa na espessura macular central (com a instilação de pilocarpina, 262,27 ± 19,34 µm; com a instilação de ciclopentolato, 265,93 ± 17,91 µm; p=0,016). Observou-se que a miose associada à pilocarpina (p<0,001) e o desvio miópico (p<0,001) foram mais severos nos olhos azuis que nos castanhos. Conclusão: A acomodação farmacológica pode alterar medidas oculares como a espessura da coroide e o comprimento axial. Essa possibilidade deve ser levada em consideração ao se efetuarem medições oculares, tais como cálculos de potência de lentes intraoculares.(AU)

Agreement of Corrected Intraocular Pressure Values Between Corvis ST and Pentacam in Patients With Keratoconus, Subclinical Keratoconus, and Normal Cornea.

PURPOSE: To analyze the agreement of corrected intraocular pressure (IOP) values between Corvis ST (ΔIOP1) and Pentacam (ΔIOP2) in patients with keratoconus (KC), subclinical KC (sub-KC), and normal cornea. METHODS: In total, 235 eyes were divided into KC, sub-KC, and control groups. Differences in ΔIOP1 (biomechanically corrected IOP minus uncorrected IOP) and ΔIOP2 (central corneal thickness-corrected amounts of IOP) were analyzed within and among groups. Topographical and biomechanical differences were compared among the 3 groups. Factors affecting differences between ΔIOP1 and ΔIOP2 were analyzed. Agreement analysis of ΔIOP2 and ΔIOP1 was performed by Bland-Altman plots for all 3 groups. RESULTS: Mean ΔIOP1 was highest in the KC group (1.23 ± 0.84 mm Hg), followed by sub-KC and control groups (all P < 0.05). Deformation amplitude ratio at 2 mm (DA-2 mm), integrated radius, stiffness parameter at first applanation, and Corvis biomechanical index values significantly differed between sub-KC and control groups. The differences between ΔIOP1 and ΔIOP2 were affected by stiffness parameter at first applanation, after adjusting for central corneal thickness and age, in all 3 groups. The lowest agreement between ΔIOP2 and ΔIOP1 was observed in the KC group (mean difference: 1.90 mm Hg; 95% limit of agreement ranged from -0.2 to 3.9 mm Hg). CONCLUSIONS: Among the 3 groups in this study, the KC group exhibited the worst consistency between ΔIOP2 and ΔIOP1. For the sub-KC and control groups, corrected IOP values derived by Pentacam were similar to Corvis ST. Ophthalmologists should carefully consider the mechanical properties of eyes with KC during IOP management.

The Interday Repeatability of Parameters for the Assessment of Progressive Disease in Subjects With Less Advanced Keratoconus.

PURPOSE: To evaluate the interday repeatability in the measurement of parameters used for the detection of progression of keratoconus by prediction limits (PL) for single measurements, and the repeatability coefficient (RC) for the mean of replicate measurements. DESIGN: Prospective reliability analysis for cases and control eyes. METHODS: Twenty-five eyes in 25 subjects with KC and 25 eyes in 25 healthy controls were included. Four consecutive measurements were made, 3 days apart, with a Pentacam HR tomographic instrument (denoted the Pentacam) and a Nidek ARK 560-A auto-keratometer (denoted the keratometer). Main outcome measures were the intra- and interday RC of parameters used in the detection of progression of keratoconus. RESULTS: The most repeatable parameter obtained with the Pentacam was the curvature power of the central flat meridian (K1, 0.44 D [RC], -0.55 to 0.60 diopter [D] [PL]), followed by the central steep meridian (K2, 0.72 D [RC], -0.90 to 0.94 D [PL]). The interday repeatability of K1 and K2 was similar when using the keratometer (K1, 0.32 D [RC], -0.66 to 0.57 D [PL], K2, 0.93 D [RC], -1.36 to 1.08 D [PL]). The interday repeatability of the curvature power of the steepest point (Kmax, 0.84 D [RC], -0.90 to 1.11 D [PL]) would benefit from being stratified: RC = 0.44 D and PL = -0.49 to 0.67 D for Kmax < 49.0 D, and RC = 1.08 D and PL = -1.19 to 1.42 D for Kmax ≥ 49.0 D. CONCLUSIONS: The interday repeatability of measurements, single or replicate, in subjects with keratoconus should be considered when diagnosing progressive disease. K1 exhibited the best intraday repeatability. Kmax benefits from being stratified according to disease severity.

Precision of the Nidek Tonoref II autokeratometer: how many repeated measurements are required?

PURPOSE: To determine the minimal number of repeated measurements required for precise Nidek Tonoref II autokeratometry. METHODS: This prospective, non-intervention study was performed at the Department of Ophthalmology, Randers, Denmark. We used the Nidek Tonoref II autokeratometer to perform 10 successive measurements on 100 right eyes of cooperative individuals. Each keratometry was converted to the spherical equivalent power (SE), while the net astigmatism was converted to polar values along zero (KP(0)) and 45 degrees (KP(45)). All units were in dioptres (D). The precision was calculated as the mean absolute difference between paired measurements, using one or the average of two, three, four or five autokeratometries. Statistical assessment was performed with Dunn's test for repeated measurements with a Bonferroni correction. RESULTS: The precision of SE, KP(0) and KP(45) increased statistically significantly from one to three measurements, with no significant improvement for autokeratometries based on four or five measurements. There was no significant precision difference between one and two measurements. CONCLUSION: A single keratometry is inadequate, but the vector average of three measurements is sufficient for precise autokeratometry with the Tonoref II device. The consistent use of three keratometries with this device may increase the precision of spherical and toric IOL calculation.

Repeatability of Zone Averages Compared to Single-Point Measurements of Maximal Curvature in Keratoconus.

PURPOSE: To evaluate the repeatability of curvature zone averages centered on the point of maximum curvature (Kmax) compared to that of the single-point Kmax. DESIGN: Comparative reliability analysis. METHODS: Setting: American University of Beirut Medical Center, Beirut, Lebanon. STUDY POPULATION: Sixty-five eyes of 65 adult keratoconus patients. Patients with other ocular disease, history of ocular surgery or trauma, and contact lens wear within 2 weeks of image acquisition were excluded. OBSERVATION PROCEDURES: Eyes were evaluated with 3 consecutive scans using the Galilei dual Scheimpflug-Placido system. MAIN OUTCOME MEASURES: Repeatability of axial and instantaneous Kmax single points, and zone averages with radii of 0.1-2.0 mm, centered on them. Repeatability was assessed by within-subject standard deviations, repeatability limits (r), and intraclass correlation coefficients. RESULTS: Axial curvature zone averaging yielded clinically acceptable repeatability only in eyes with Kmax ≤50 diopters (D), for radii of 1.5 mm and 2.0 mm (r = 0.87 D and r = 0.76, respectively, vs r = 0.91 for the single-point axial Kmax). Compared to instantaneous Kmax, clinically acceptable repeatability was achieved with instantaneous zone averages of at least 1.5 mm radius in eyes with Kmax ≤50 D (r = 0.99 D and r = 0.70 D, respectively) and 2.0 mm radius in eyes with Kmax >50 D (r = 2.28 D and r = 0.87 D, respectively). For all eyes, the repeatability limit of the location of Kmax was 0.82 mm and 0.80 mm for axial and instantaneous curvature, respectively. CONCLUSIONS: Instantaneous curvature zone averages centered on Kmax yielded a greater improvement in repeatability than axial zone averages and reached clinical adequacy with radii of at least 1.5 mm, for eyes with Kmax ≤50 D, and with a 2.0 mm radius for eyes with Kmax >50 D.

Comparison of variables measured with a Scheimpflug device for evaluation of progression and detection of keratoconus.

Keratoconus is a progressive ectatic corneal disorder, which can result in severe visual impairment. The new ABCD keratoconus classification system allows differentiated description of the disease. Aim of the study was to evaluate the components of this novel staging system (ARC, PRC, thinnest pachymetry) as well as topometric indices, deviation of normality indices, and other parameters in terms of repeatability and reliability. 317 eyes with keratoconus were examined twice with a Scheimpflug device (Pentacam, Oculus). Bland Altman analysis and intraclass correlations were carried out to evaluate the parameters repeatability and reliability. Apart from IHA (ICC = 0.730), all parameters showed excellent reliability (ICC > 0.900). ARC, PRC, thinnest pachymetry, Kmax, CKI, KI, Rmin, and Progression Avg were the best repeatable parameters with relative repeatability values < 2.5%. Other parameters performing well in terms of repeatability were IHD, ISV, IVA, and final D (RR < 13%). Regression analysis revealed consistently high repeatability along all stages of keratoconus for PRC, thinnest pachymetry, and CKI. All parameters of the ABCD staging system showed excellent reliability and repeatability, PRC and thinnest pachymetry even at all stages of keratoconus and can consequently be reliably used in the determination of keratoconus progression.

Repeatability of Orbscan III for anterior segment parameters in normal eyes.

PURPOSE: Assessment of repeatability of Orbscan III in measuring steep keratometry (sKm), flat keratometry (fKm), thinnest corneal thickness (TCT), anterior chamber depth (ACD), white-to-white diameter (WTW) and 3 mm and 5 mm zonal irregularity in healthy eyes. METHODS: In this prospective observatioanl study 100 eyes of 50 participants underwent three consecutive scans on Orbscan III by a single examiner with a gap of 5 minutes between scans. Statistical analysis was performed to assess the repeatability of sKm, fKm, TCT, WTW, ACD and parameters of 3- and 5 mm irregularity. Within subject standard deviation (Sw), coefficient of variation (CoV) and test retest variability (TRT) was calculated for the commonly used parameters. WERE THE MAIN OUTCOME MEASURES.: The repeatability of sKm, fKm, TCT, WTW, ACD, 3 mm and 5 mm zonal irregularity on Orbscan III. RESULTS: Total of 50 patients (25 male and 25 female) who fulfilled inclusion and exclusion criteria were assessed. sKm, fKm, TCT and WTW were found to have a TRT of 0.31, 0.29. 21.5 and 0.27, respectively, and the ICC values were found to be over 0.9, denoting high repeatability. Repeat measurements of parameters of irregularity and ACD were found to be statistically similar, again denoting similarity between repeat measurements. CONCLUSION: Orbscan III provides repeatable measurements of Sim-k, anterior chamber depth, thinnest corneal thickness, 3 mm and 5 mm zonal irregularity and white-to-white diameter in healthy eyes.

Visual quality observation of clear lens extraction by ultrasonic phacoemulsification and intraocular lens implantation in a child with microspherophakia: A case report.

RATIONALE: Microspherophakia is characterized by a small, spherical crystalline lens with increased sagittal diameter. Because of the uncertainty about the outcome, as well as the complexity of the operation and development of complications, the management and timing of surgical intervention for microspherophakia are still debated. Lens extraction is effective for avoiding the risk of pupillary blockage, but the outcome after operation is controversial. The iTrace (Tracey, USA) report shows the influence of low-order aberrations (LOA) and high-order aberrations (HOA), which may be valuable in predicting postoperative outcome. Our report concerns a child with microspherophakia who underwent lens extraction via the analysis of visual quality by iTrace. PATIENT CONCERNS: Our report is on the case of a 7-year-old girl whose parents observed she had to bring her papers and books extremely close to her face to read. On examination, the girl was bilaterally diagnosed microspherophakia with a small tremble lens. The objective refraction was -15.0 diopter of spherical power (DS)/-1.00 diopter of cylindrical power (DC) × 180 right eye (OD) and -12.5 DS/-1.50 DC × 20 left eye (OS). The HOA of OD and OS were high up to 0.926 and 0.659, respectively by iTrace. The visual quality remained terrible after correcting LOA (high myopia and astigmatism). According to iTrace report, the patient would get a good visual quality by extracting the clear lens with HOA from cornea after correcting LOA. The girl's parent opted for surgery on the left eye. DIAGNOSIS: Due to the patient's symptoms, examination results, she was diagnosed with microspherophakia. INTERVENTIONS: The patient underwent clear lens extraction by ultrasonic phacoemulsification and intraocular lens implantation. OUTCOMES: The first day after operation, total HOA was decreased to 0.077. Total LOA was 0.713. Corrected distance visual acuity (CDVA) is 20/20. One week after surgery, HOA was 0.110 and LOA was 0.328. CDVA was 20/25. CDVA was still 20/25 one month after surgery. The total HOA was 0.110 and the LOA was 0.334 by iTrace. LESSONS: ITrace not only plays an important role in analyzing potential reasons of undesirable preoperative visual quality but also can predict postoperative outcomes. All these functions are helpful for determining surgical intervention of microspherophakia cases.

Clinical Accuracy of an Advanced Corneal Topographer with Tear-Film Analysis in Functional and Structural Evaluation of Dry Eye Disease.

Purpose: Dry eye disease (DED) is a common condition that significantly lowers the quality of life. As the disease grows more prevalent, multiple commercial instruments have been developed to measure the ocular surface of dry eyes, but no single device has yet been successful in comprehensive measurements. The current study aimed to investigate the clinical accuracy and utility of the Antares topographer in the diagnosis of DED.Methods: Thirty-three consecutive patients underwent analyses of their non-invasive first tear-film break-up time (NIF-BUT), tear meniscus height (TMH) and meibography with the Antares topographer. The meibography with the LipiView scan was conducted. Slit-lamp examinations were done for assessments of meibomian glands (MG) and fluorescein tear-film break-up time (FBUT). Schirmer 1 test was done. The Ocular Surface Disease Index (OSDI) scores were graded.Results: Thirty-three eyes of 33 patients (mean age 61.5 ± 10.6 years, range 37.5-76.4 years, 27.3% males) completed the study. According to the Antares measurements, the NIF-BUT of the patient population was 5.0 ± 3.4 seconds on average (1.1-15.0 seconds), and the TMH was 0.2 ± 0.1 mm at center (0.1-0.5 mm). The average OSDI score was 22.4 ± 16.6 points (0.0-79.5 points). When correlations were calculated, significant correlations were found between the NIF-BUT from the Antares topographer and FBUT (r = 0.538, P = .001), and between MG dropout from the Antares topographer and that from the LipiView interferometer (r = 0.446, P=.009). Antares NIF BUT and FBUT were in agreement with one another (95% limits of agreement (LOA) -5.04 ± 6.37, P=.198) as were the infrared images from the Antares topographer and those from the LipiView interferometer (95% LOA -0.25 ± 0.35, P=.073).Conclusion: The Antares topographer is useful in the diagnosis of DED. Among its outputs, the NIF-BUT and MG dropout most closely correlated with currently accepted modes of diagnosis. However, concurrent clinical examinations are recommended for clinical follow-up.

A Comparative Study of Total Corneal Power Using a Ray Tracing Method Obtained from 3 Different Scheimpflug Camera Devices.

PURPOSE: We sought to assess the agreement of ray-traced corneal power values by 3 Scheimpflug tomographers tp construct the corresponding arithmetic adjustment factor in comparison with an automated keratometer (IOLMaster) and a conventional Placido-based topographer (Allegro Topolyzer). DESIGN: Prospective reliability analysis. METHODS: A total of 74 eyes from 74 healthy subjects who underwent corneal power measurements using Pentacam, Sirius, Galilei, IOLMaster, and Allegro Topolyzer were included. Ray-traced corneal power values, such as total corneal refractive power (TCRP), mean pupil power (MPP), total corneal power (TCP), mean keratometry (Km), and simulated keratometry (SimK) were recorded respectively and analyzed using one-way analysis of variance (ANOVA) and Bland-Altman plots. RESULTS: Among the 3 ray-traced corneal power values, TCRP and MPP did not differ significantly (P = 0.81), whereas TCP presented a slightly significant larger value (P < 0.001). Compared to Km or SimK, corneal power measurements by the ray tracing method exhibited significantly lower values (P < 0.001). Bland-Altman plots disclosed that the 3 Scheimpflug tomographers showed similar 95% limits of agreement after arithmetic adjustment compared with Km (-0.40 to 0.40 D, -0.39 to 0.39 D, and -0.35 to 0.34 D) or SimK (-0.50 to 0.51 D, -0.43 to 0.42 D, and -0.46 to 0.46 D). CONCLUSIONS: Ray-traced corneal power values obtained using 3 Scheimpflug tomographers with default diameter settings were similar, indicating that they could be used interchangeably in daily clinical practice. The 3 Scheimpflug tomographers were satisfactory in agreement after arithmetical adjustment compared with conventional automated keratometer or Placido-based topographer.

Comparing the postoperative refractive predictability of Pentacam HR and IOLMaster 500 after a multifocal intraocular lens implantation / Comparação da previsibilidade refrativa pós-operatória do Pentacam HR e IOLMaster 500 após implante de lentes intraoculares multifocais

ABSTRACT Purpose: To compare the postoperative refractive predictability of IOLMaster 500 and Pentacam HR on the basis of keratometry and anterior chamber depth values in eyes with an indication for multifocal intraocular lens (IOL) implantation. Methods: This was a retrospective study conducted on 118 eyes treated with phacoemulsification and multifocal intraocular lens implantation. Only the eyes that achieved emmetropia in the dynamic refraction performed on postoperative day 30 were included. Haigis' formula was used in each case to calculate the intraocular lens power, and the intraocular lens with the target refraction closest to emmetropia was implanted. Four lens calculation scenarios were tested by combining keratometry and anterior chamber depth measurements obtained using the two devices. Results: IOLMaster 500 and Pentacam HR differed with regard to mean keratometry (D 0.07 ± 0.03 D; p=0.0065) and anterior chamber depth (D 0.08 ± 0.01 mm; p<0.001). In the analysis of covariance, the following differences were obtained using the Haigis' formula when confronted with the biometric values obtained by inserting keratometry and anterior chamber depth values, respectively: Penta/IOL x IOL/Penta (0.13 ± 0.03; p<0.0001); Penta/Penta × IOL/Penta (0.13 ± 0.03; p<0.0001); Penta/IOL × IOL/IOL (0.11 ± 0.03; p=0.001); Penta/Penta × IOL/IOL (0.11 ± 0.03; p=0.002); IOL/IOL × IOL/Penta (0.02 ± 0.03; p=0.865); and Penta/IOL × Penta/Penta (0.002 ± 0.03; p=0.99). The difference was smaller when measuring the anterior chamber depth using the IOLMaster 500, regardless of which device was used to measure keratometry. Conclusions: Pentacam HR significantly differed from IOLMaster 500 when calculating keratometry. As regards the anterior chamber depth, the two devices were equally accurate.

RESUMO Objetivo: Comparar a previsibilidade refrativa pós-operatória do IOLMaster 500 e Pentacam HR com base nos valores de ceratometria e profundidade de câmara anterior nos olhos com indicação de implante de lentes intraoculares multifocais. Métodos: Estudo retrospectivo realizado em 118 olhos tratados com facoemulsificação e implante de lentes intraoculares multifocal. Apenas os olhos que atingiram a emetropia na refração dinâmica no 30º dia pós-operatório foram incluídos. A fórmula de Haigis foi usada em cada caso para calcular o poder das lentes intraoculares, e a lente intraocular com a refração alvo mais próxima da emetropia foi implantada. Cenários de cálculo de quatro lentes foram testados pela combinação de medidas de ceratometria e profundidade de câmara anterior obtidas usando os dois dispositivos. Resultados: IOLMaster 500 e Pentacam HR diferiram quanto à média de ceratometria (D 0,07 ± 0,03 D; p=0,0065) e profundidade de câmara anterior (D 0,08 ± 0,01 mm; p<0,001). Na análise da covariância, as seguintes diferenças foram obtidas usando a fórmula de Haigis quando confrontadas com os valores biométricos obtidos pela inserção dos valores de ceratometria e profundidade de câmara anterior, respectivamente: Penta/IOL x IOL/Penta (0,13 ± 0,03; p<0,0001); Penta/Penta x IOL/Penta (0,13 ± 0,03; p<0,0001); Penta/IOL x IOL/IOL (0,11 ± 0,03; p=0,001); Penta/Penta x IOL/IOL (0,11 ± 0,03; p=0,002); IOL/IOL x IOL/Penta (0,02 ± 0,03; p=0,865); Penta/IOL x Penta/Penta (0,002 ± 0,03; p=0,99). A diferença foi menor ao medir a profundidade da câmara anterior usando o IOLMaster 500, independentemente de qual dispositivo foi usado para medir a ceratometria. Conclusões: O Pentacam HR diferiu significativamente do IOLMaster 500 no cálculo de ceratometria. Quanto à profundidade da câmara anterior, os dois dispositivos foram igualmente precisos.

Corneal differences between healthy and subclinical patients assessed using two diferente corneal tomographers / Diferenças entre as córneas de pacientes saudáveis e pacientes subclínicos avaliados com dois tipos de tomógrafos de córnea

ABSTRACT Purpose: To analyze subclinical keratoconus topography indexes using Pentacam and Orbscan-II measurements to identify evidences for seeking sensitive indexes to screen and diagnose subclinical keratoconus. Methods: Fifty healthy participants (50 eyes) and 40 patients with subclinical keratoconus (40 eyes) were included. Seven common parameters including corneal thickness at the thinnest point; minimum curvature of the front surface (minimum simulated keratometry value, SimK's Min); maximum curvature of the front surface (maximum simulated keratometry value, SimK's Max); the frontal corneal surface best-fit spherical radius of the curvature; the back corneal surface best-fit spherical radius of curvature; the anterior corneal surface height (anterior Diff value); and the posterior corneal surface height (posterior Diff value) measured by Pentacam and Orbscan-II between normal and subclinical keratoconus eyes were compared. Results: Statistical differences between the healthy and subclinical keratoconus groups (p<0.01) were found in all corneal parameters measured using both devices. Differences in the minimum curvature of the front surface (SimK's Min), thinnest point, anterior Diff value, and posterior Diff value were significant between Pentacam and Orbscan-II in the subclinical keratoconus group (p<0.05). Conclusion: The findings of this study identify the differences between normal and subclinical keratoconus eyes at the minimum curvature of the front surface, maximum curvature of the front surface, frontal corneal surface best-fit spherical radius of curvature, back corneal surface best-fit spherical radius of curvature, Anterior Diff value, and Posterior Diff value measures using Orbscan II and Pentacam that can help eye care practitioners clinically diagnose subclinical keratoconus.

RESUMO Objetivo: Analisar os índices subclínicos de to pografia de ceratocone utilizando as medidas feitas com Pentacam e com Orbscan-II para identificar evidências para a busca de índices sensíveis para triagem e diagnóstico de ceratocone subclínico. Métodos: Cinquenta participantes saudáveis (50 olhos) e 40 pacientes com ceratocone subclínico (40 olhos) foram incluídos. Sete parâmetros comuns, incluindo a espessura da córnea no ponto mais fino; a curvatura mínima da superfície frontal (valor mínimo da ceratometria simulada, Min de SimK); a curvatura máxima da superfície frontal (valor máximo da ceratometria simulada, Max de SimK); a superfície frontal e a superfície posterior da córnea de melhor ajuste ao raio da curvatura, a altura da superfície anterior da córnea (valor Diff anterior) e a altura da superfície corneana posterior (valor Diff posterior) medidos pelo Pentacam e pelo Orbscan-II entre os olhos normais e com ceratocone subclínico foram comparados. Resultados: As diferenças estatísticas entre os grupos saudável e com ceratocone subclínico (p<0,01) foram encontradas em todos os parâmetros corneanos medidos usando ambos os dispositivos. Diferenças na curvatura mínima da superfície frontal (Min de SimK) no ponto mais fino, no valor Diff anterior e no valor Diff posterior foram significativas entre Pentacam e Orbscan-II no grupo com ceratocone subclínico (p<0,05). Conclusão: Os achados deste estudo identificam as diferenças entre olhos normais e com ceratocone subclínico para a curvatura mínima da superfície frontal, a curvatura máxima da superfície frontal, a superfície corneana frontal e a superfície corneana posterior de melhor ajuste ao raio esférico da curvatura e as medidas de Diff anterior e posterior usando Orbscan II e o Pentacam que podem auxiliar os profissionais de oftalmologia a diagnosticar clinicamente o ceratocone subclínico.

Characterising keratometry in different dog breeds using an automatic handheld keratometer.

BACKGROUND: Keratometry is clinically important and is routinely performed as part of human ophthalmic examination. In veterinary ophthalmology, little is known about keratometry in dogs, and its practical application has been limited. The present study aimed to describe keratometry in some dog breeds popular in Japan using a handheld keratometer. METHODS: Client-owned dogs of various signalment were enrolled prospectively in the keratometry examination. Interbreed variations in mean corneal curvatures (R1R2avg) and corneal astigmatism (Δ(R1-R2)) were evaluated statistically with respect to their bodyweight based on the data which fulfilled the predetermined inclusion criteria. P<0.05 was considered statistically significant. RESULTS: On examination of 237 dogs from 16 different breeds, R1R2avg (mean±sd) ranged from 7.54±0.30 mm in Pomeranians to 9.28±0.19 mm in golden retrievers. Δ(R1-R2) (mean±sd) ranged from 0.22±0.11 mm in miniature schnauzers to 0.57±0.30 mm in French bulldogs. CONCLUSION: The present study successfully described keratometry in 16 dog breeds. The study revealed considerable interbreed variations in both R1R2avg and Δ(R1-R2), which did not necessarily correlate with bodyweight. These results are useful both clinically in fitting contact lenses in the management of corneal diseases and non-clinically in optometric studies in dogs.

Comparing the postoperative refractive predictability of Pentacam HR and IOLMaster 500 after a multifocal intraocular lens implantation.

PURPOSE: To compare the postoperative refractive predictability of IOLMaster 500 and Pentacam HR on the basis of keratometry and anterior chamber depth values in eyes with an indication for multifocal intraocular lens (IOL) implantation. METHODS: This was a retrospective study conducted on 118 eyes treated with phacoemulsification and multifocal intraocular lens implantation. Only the eyes that achieved emmetropia in the dynamic refraction performed on postoperative day 30 were included. Haigis' formula was used in each case to calculate the intraocular lens power, and the intraocular lens with the target refraction closest to emmetropia was implanted. Four lens calculation scenarios were tested by combining keratometry and anterior chamber depth measurements obtained using the two devices. RESULTS: IOLMaster 500 and Pentacam HR differed with regard to mean keratometry (D 0.07 ± 0.03 D; p=0.0065) and anterior chamber depth (D 0.08 ± 0.01 mm; p<0.001). In the analysis of covariance, the following differences were obtained using the Haigis' formula when confronted with the biometric values obtained by inserting keratometry and anterior chamber depth values, respectively: Penta/IOL x IOL/Penta (0.13 ± 0.03; p<0.0001); Penta/Penta × IOL/Penta (0.13 ± 0.03; p<0.0001); Penta/IOL × IOL/IOL (0.11 ± 0.03; p=0.001); Penta/Penta × IOL/IOL (0.11 ± 0.03; p=0.002); IOL/IOL × IOL/Penta (0.02 ± 0.03; p=0.865); and Penta/IOL × Penta/Penta (0.002 ± 0.03; p=0.99). The difference was smaller when measuring the anterior chamber depth using the IOLMaster 500, regardless of which device was used to measure keratometry. CONCLUSIONS: Pentacam HR significantly differed from IOLMaster 500 when calculating keratometry. As regards the anterior chamber depth, the two devices were equally accurate.

Repeatability of anterior segment measurements by optical coherence tomography combined with Placido disk corneal topography in eyes with keratoconus.

Corneal tomography is an important tool to identify and follow up eyes with keratoconus. Our study evaluate the repeatability of the automatic measurements provided in keratoconic eyes by a new anterior-segment optical coherence tomographer (AS-OCT) combined with Placido-disk topography (MS-39, CSO) and assess their agreement with the corresponding measurements taken with a rotating Scheimpflug camera combined with Placido-disk topography (Sirius, CSO). Mean simulated keratometry, posterior and total corneal power, total corneal astigmatism, corneal asphericity, thinnest corneal thickness, epithelial thickness, corneal diameter, and aqueous depth were evaluated. Repeatability was assessed using test-retest variability, the coefficient of variation, and the intraclass correlation coefficient; agreement was assessed by the 95% limits of agreement. Good repeatability was achieved for most parameters. Moderate repeatability was found for total corneal astigmatism measurements. The repeatability of mean simulated keratometry and total corneal power measurements worsened with more severe stages of keratoconus with a statistically significant relationship between the individual coefficient of variation and corneal power values. Agreement with the Scheimpflug camera was moderate for aqueous depth and thinnest corneal thickness and poor for most other measured parameters. The good repeatability of automatic measurements suggests the new AS-OCT device to be a viable option in clinical practice of eyes with keratoconus.

Validation of posterior corneal curvature measurements with color light-emitting diode topography.

PURPOSE: To evaluate the intrasession repeatability and validity of posterior corneal curvature and astigmatism measurements provided by a color light-emitting diode reflection topography system in healthy eyes. METHODS: A total of 40 healthy eyes of 40 patients (age, 16-66 years) were enrolled. A complete eye examination was performed in all cases including posterior topographic analysis with two systems: the Scheimpflug-based system (Pentacam; Oculus Optikgeräte GmbH, Wetzlar, Germany) and the Cassini system (i-Optics; Ophthec, The Hague, The Netherlands). With this last system, three consecutive measurements were taken to assess the level of intrasession repeatability (within-subject standard deviation, Sw; intraclass correlation coefficient). The Bland & Altman analysis was used to evaluate the interchangeability of both devices. RESULTS: The Sw was ⩽0.06 mm for all posterior corneal radius measurements, with intraclass correlation coefficient of ⩾0.960. The Sw for the magnitude of astigmatism, J0, and J45 were 0.15, 0.04, and 0.04 D, respectively, with intraclass correlation coefficient values of 0.876, 0.897, and 0.840, respectively. Statistically significant differences between devices were found in all parameters evaluated (p ⩽ 0.025). The interchangeability analysis revealed the presence of clinically relevant limits of agreement for the flattest (0.03 to 0.50 mm) and steepest posterior corneal radii (-0.01 to 0.39 mm). In contrast, limits of agreements were not clinically relevant for the magnitude of posterior astigmatism (-0.17 to 0.27 D) and their power vector components (-0.11 to 0.15 D). CONCLUSION: The Cassini system provides consistent measures of posterior corneal curvature and astigmatism in healthy eyes, but only measures of posterior astigmatism can be considered as interchangeable with those provided by the Pentacam.

Comparison of Preoperative Parameter Measurements Using an Optical Biometer, Automated Keratometer, and a Placido-Based Topographer Module.

OBJECTIVES: To assess the agreement of corneal power, corneal astigmatism, axis location, and astigmatic vector component measurements using a Lenstar LS900, a T-cone add-on, and an ARK 1S autorefractor, furthermore, to assess instrument agreement in a subset of astigmatic eyes. METHODS: Retrospective analysis of keratometric readings from 3 instruments for 66 eyes undergoing cataract surgery at the Maryland Veterans Affairs Medical Center from November 2014 to 2015. Agreement in corneal power, mean corneal power, axis location, and astigmatic vector components (J0, J45) between devices was evaluated. Comparability was assessed using intraclass correlation, analysis of variance (ANOVA) one-way analysis, Bland-Altman analysis, and power vector analysis. Intraclass correlation was then assessed for a subset of 42 eyes with corneal astigmatism greater than or equal to 1 D. RESULTS: The intraclass correlation between instruments was 0.941 for corneal power, 0.788 for corneal astigmatism, 0.932 for J0, and 0.809 for J45. The ANOVA one-way repeated P values comparing Kf, Ks, Km, corneal astigmatism, axis location, J0, and J45 were all greater than 0.05. Power vector analysis showed nearly all values between instruments to be within ±0.5 D. Finally, the intraclass correlation between instruments in eyes with ≥1 D of corneal astigmatism as measured by the T-cone was 0.946 for corneal power, 0.837 for corneal astigmatism, 0.948 for J0, and 0.950 for J45. CONCLUSIONS: The high level of agreement between all devices indicates the instruments may be used interchangeably. Our data suggest that this may also be true for the subset of eyes with greater than or equal to 1 D in astigmatism, highlighting the toric intraocular lens population.

Corneal differences between healthy and subclinical patients assessed using two diferente corneal tomographers.

PURPOSE: To analyze subclinical keratoconus topography indexes using Pentacam and Orbscan-II measurements to identify evidences for seeking sensitive indexes to screen and diagnose subclinical keratoconus. METHODS: Fifty healthy participants (50 eyes) and 40 patients with subclinical keratoconus (40 eyes) were included. Seven common parameters including corneal thickness at the thinnest point; minimum curvature of the front surface (minimum simulated keratometry value, SimK's Min); maximum curvature of the front surface (maximum simulated keratometry value, SimK's Max); the frontal corneal surface best-fit spherical radius of the curvature; the back corneal surface best-fit spherical radius of curvature; the anterior corneal surface height (anterior Diff value); and the posterior corneal surface height (posterior Diff value) measured by Pentacam and Orbscan-II between normal and subclinical keratoconus eyes were compared. RESULTS: Statistical differences between the healthy and subclinical keratoconus groups (p<0.01) were found in all corneal parameters measured using both devices. Differences in the minimum curvature of the front surface (SimK's Min), thinnest point, anterior Diff value, and posterior Diff value were significant between Pentacam and Orbscan-II in the subclinical keratoconus group (p<0.05). CONCLUSION: The findings of this study identify the differences between normal and subclinical keratoconus eyes at the minimum curvature of the front surface, maximum curvature of the front surface, frontal corneal surface best-fit spherical radius of curvature, back corneal surface best-fit spherical radius of curvature, Anterior Diff value, and Posterior Diff value measures using Orbscan II and Pentacam that can help eye care practitioners clinically diagnose subclinical keratoconus.