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He Y, Ma BS, Zeng JH, Ma DJ. Corneal optical density: Structural basis, measurements, influencing factors, and roles in refractive surgery. Front Bioeng Biotechnol 2023; 11:1144455. [PMID: 37091331 PMCID: PMC10117965 DOI: 10.3389/fbioe.2023.1144455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 03/29/2023] [Indexed: 04/08/2023] Open
Abstract
The cornea is the main refractive medium of the human eye, and its clarity is critical to visual acuity. Corneal optical density (COD) is an important index to describe corneal transparency. Intact corneal epithelial and endothelial cells, regular arrangement of collagen fibers in the stroma, and normal substance metabolism are all integral for the cornea to maintain its transparency. In the last two decades, the Pentacam Scheimpflug imaging system has emerged as a breakthrough for the measurement of COD (also called corneal densitometry). It has been found that a wide variety of factors such as age, refractive status, and corneal diseases can affect COD. Different corneal refractive surgery methods also change COD in different corneal regions and layers and affect visual acuity following the surgery. Thus, COD has gradually become a significant indicator to evaluate corneal health, one on which the attention of clinicians has been increasingly focused.
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Affiliation(s)
- Ye He
- Changsha Aier Eye Hospital, Changsha, China
| | - Bo-Sheng Ma
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jun-Hao Zeng
- Xiangya School of Medicine, Central South University, Changsha, China
| | - Dai-Jin Ma
- Changsha Aier Eye Hospital, Changsha, China
- *Correspondence: Dai-Jin Ma,
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Martin R, Nuñez L, Sastre J, De juan V, Rodriguez G. Constancy of the Orbscan acoustic factor to detect contact lens‐induced corneal swelling. Clin Exp Optom 2021; 94:352-60. [DOI: 10.1111/j.1444-0938.2010.00578.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Raul Martin
- IOBA‐Eye Institute and School of Optometry, Department of Physics TAO, University of Valladolid, Valladolid, Spain
E‐mail:
| | - Laura Nuñez
- IOBA‐Eye Institute and School of Optometry, Department of Physics TAO, University of Valladolid, Valladolid, Spain
E‐mail:
| | - Jesus Sastre
- IOBA‐Eye Institute and School of Optometry, Department of Physics TAO, University of Valladolid, Valladolid, Spain
E‐mail:
| | - Victoria De juan
- IOBA‐Eye Institute and School of Optometry, Department of Physics TAO, University of Valladolid, Valladolid, Spain
E‐mail:
| | - Guadalupe Rodriguez
- IOBA‐Eye Institute and School of Optometry, Department of Physics TAO, University of Valladolid, Valladolid, Spain
E‐mail:
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Oliveira CM, Ribeiro C, Franco S. Corneal imaging with slit‐scanning and Scheimpflug imaging techniques. Clin Exp Optom 2021; 94:33-42. [DOI: 10.1111/j.1444-0938.2010.00509.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
| | - Celina Ribeiro
- Centre/Department of Physics, University of Minho, Portugal
E‐mail:
| | - Sandra Franco
- Centre/Department of Physics, University of Minho, Portugal
E‐mail:
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Garcia PN, Chamon W, Allemann N. Comparability of corneal thickness and opacity depth assessed by OCT and UBM. Graefes Arch Clin Exp Ophthalmol 2021; 259:1915-1923. [PMID: 33763731 DOI: 10.1007/s00417-021-05161-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 02/24/2021] [Accepted: 03/12/2021] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE To compare the measurement of central thickness and depth of involvement of opacity-bearing corneas at different intensities (mild, moderate, and dense) using different instruments: Visante and Optovue OCTs, ultrasound biomicroscopy (UBM), and ultrasound pachymetry (central thickness). METHODS Sample of 102 eyes: 70 eyes (68.63 %) with corneal opacity; 32 eyes (31.37%) with normal corneas. Corneal opacity grading included mild (28 eyes, 40.00 %), moderate (27 eyes, 37.57 %), and dense (15 eyes, 21.43 %). Opacity intensity was graded and documented. Central corneal thickness was determined using Optovue and Visante OCTs, ultrasound pachymetry, and UBM VuMax (50 MHz), and depth of corneal opacity, using Optovue and Visante OCTs and UBM. RESULTS Total corneal thickness of the control group showed differences with a small correction factor using Optovue OCT (534.03 ± 39.88 μm), Visante OCT (523.72±38.70 μm), and ultrasound pachymetry (529.84 ± 39.76 μm), and were higher when compared to UBM (492.06 ± 37.93 μm). In mild opacity, depth measurements were the same with OCT Optovue and Visante and higher than those by UBM. In moderate opacities, there were no differences in measurements by different instruments. In dense opacities, OCT Optovue and Visante measurements were the same and higher than those by UBM. CONCLUSIONS Central corneal thickness measurements were considered higher in corneas with opacity than in normal corneas. We observed that the greatest thicknesses were measured in corneas with dense opacities. There was a difference between the measurements taken by different instruments, both in central thickness and in opacity depth in cases of mild and dense opacity, and no difference in moderate opacity.
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Affiliation(s)
- Patricia Novita Garcia
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo-Paulista School of Medicine - UNIFESP-EPM, São Paulo, Brazil.
- Department of Ophthalmology, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil.
| | - Wallace Chamon
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo-Paulista School of Medicine - UNIFESP-EPM, São Paulo, Brazil
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago - UIC, Chicago, IL, USA
| | - Norma Allemann
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo-Paulista School of Medicine - UNIFESP-EPM, São Paulo, Brazil
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago - UIC, Chicago, IL, USA
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Ho WC, Lam PTH, Chiu TYH, Yim MCM, Lau FTC. Comparison of central corneal thickness measurement by scanning slit topography, infrared, and ultrasound pachymetry in normal and post-LASIK eyes. Int Ophthalmol 2020; 40:2913-2921. [PMID: 32617805 DOI: 10.1007/s10792-020-01475-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/20/2020] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To compare central corneal thickness (CCT) measurements by scanning slit topography (SST), infrared pachymetry (IRP), and ultrasound pachymetry (USP), and their agreement in normal and post-laser in situ keratomileusis (LASIK) eyes. METHODS Sixty normal and 35 post-LASIK subjects were recruited. Only one eye from each subject was analyzed. Non-contact pachymetry was performed first, and the order for SST (Orbscan IIz) and IRP (Tonoref III) was randomized for each patient, to be followed by contact USP (Echoscan US-4000). Pearson's correlation, paired t test, and Bland-Altman plots were used to investigate association, difference, and agreement among different instruments respectively. RESULTS The measurements obtained with the instruments were highly correlated. Compared to CCT determined by USP (CCTUSP), CCT determined by SST (after correction with acoustic factor) (CCTSSTC) was thicker by 7 µm in normal eyes (P < 0.001). There was no significant difference between CCTSSTC and CCTUSP (P = 0.128), but a thickness-dependent deviation in post-LASIK eyes (P = 0.003). The CCT determined by IRP (CCTIRP) was thicker than CCTUSP in normal (P < 0.001) and post-LASIK eyes (P < 0.001) and demonstrated proportional overestimation with thinner corneas, with less predictable ultrasonic equivalent corneal thickness in normal eyes. Conversely, CCTIRP significantly underestimated CCT compared to CCTSST and showed increasing underestimation with thinner corneas in both normal and post-LASIK eyes (both P < 0.001). CONCLUSION Central corneal thickness determined by SST, IRP and USP were not interchangeable or interconvertible, probably attributed to difference in methodologies. Compensation with algorithms may improve agreements amongst instruments.
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Affiliation(s)
- Wing-Cheung Ho
- Eye Centre, Hong Kong Baptist Hospital, 222 Waterloo Road, Kowloon Tong, Hong Kong, People's Republic of China
| | - Philip Tsze-Ho Lam
- Eye Centre, Hong Kong Baptist Hospital, 222 Waterloo Road, Kowloon Tong, Hong Kong, People's Republic of China.
| | - Thomas Yee-Hang Chiu
- Eye Centre, Hong Kong Baptist Hospital, 222 Waterloo Road, Kowloon Tong, Hong Kong, People's Republic of China
| | - Mandy Ching-Man Yim
- Eye Centre, Hong Kong Baptist Hospital, 222 Waterloo Road, Kowloon Tong, Hong Kong, People's Republic of China
| | - Fion Tung-Ching Lau
- Eye Centre, Hong Kong Baptist Hospital, 222 Waterloo Road, Kowloon Tong, Hong Kong, People's Republic of China
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Cantera E, Cortes M, Sacco R, Vestri G, Micera A. Topographic indices and pachymetry in healthy adolescents obtained with Sirius topographer. Int Ophthalmol 2018; 38:2519-2526. [DOI: 10.1007/s10792-017-0763-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 10/23/2017] [Indexed: 10/18/2022]
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Belovay GW, Goldberg I. The thick and thin of the central corneal thickness in glaucoma. Eye (Lond) 2018; 32:915-923. [PMID: 29445115 DOI: 10.1038/s41433-018-0033-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/15/2018] [Accepted: 01/17/2018] [Indexed: 11/09/2022] Open
Abstract
Central corneal thickness (CCT) is an important parameter in the assessment of any potential glaucoma patient. While it affects prognosis in ocular hypertension, its value in patients diagnosed with glaucoma is less certain. There are several biological factors and genetic components that may influence glaucoma progression, which have been associated with thinner CCT. The CCT itself can be affected by several factors including ethnicity, age, sex, glaucoma medications, genetics, and the subtype of glaucoma. Besides, there is variability in the measurement of CCT between difference types of devices. These factors need to be considered in the evaluation of glaucoma patients' CCT and its effect on interpretation of intraocular pressure levels and risk stratification.
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Affiliation(s)
| | - Ivan Goldberg
- Glaucoma Unit, Sydney Eye Hospital, Sydney, Australia.,Discipline of Ophthalmology, University of Sydney, Sydney, Australia.,Eye Associates, Sydney, Australia
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Schneider M, Borgulya G, Seres A, Nagy ZZ, Nemeth J. Central Corneal Thickness Measurements with Optical Coherence Tomography and Ultrasound Pachymetry in Healthy Subjects and in Patients after Photorefractive Keratectomy. Eur J Ophthalmol 2018; 19:180-7. [DOI: 10.1177/112067210901900202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Purpose To compare central corneal thickness measurements made using two different methods, optical coherence tomography (OCT) and ultrasound pachymetry, applied both in normal eyes and in eyes on which photorefractive keratectomy (PRK) had been performed. A second objective was to assess the intrasession variability of OCT measurements. Methods In this prospective study, central corneal thickness was measured in 20 normal subjects (normal group) and in 20 PRK patients using the StratusOCT instrument model 3000 (Carl Zeiss Meditec), and also with an ultrasound pachymeter. Five OCT measurements were performed using the Fast Macular Thickness protocol. Corneal thickness data were obtained with the Scan Profile analysis protocol. The OCT measurement results were compared with the mean value of three ultrasound pachymetry measurements for the same eye. Results The pachymetry–OCT correlation coefficients were 0.96 and 0.97 in the normal and PRK groups, respectively (p=0.14). Neither linear regression nor Bland-Altmann analysis revealed any significant systematic measurement error. Intrasession standard deviations in the normal and PRK groups were 4.9 μm and 3.8 μm, respectively. Conclusions Noncontact central corneal thickness measurements made using the StratusOCT instrument are accurate and reproducible, both in normal subjects and in post-PRK patients. The instrument system does not need any modifications to correctly detect and measure the center of the cornea.
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Affiliation(s)
- Miklos Schneider
- Department of Ophthalmology, Semmelweis University, Faculty of Medicine, Budapest
| | - Gabor Borgulya
- School of PhD Studies, Semmelweis University, Budapest - Hungary
| | - Andras Seres
- Department of Ophthalmology, Semmelweis University, Faculty of Medicine, Budapest
| | - Zoltan Z. Nagy
- Department of Ophthalmology, Semmelweis University, Faculty of Medicine, Budapest
| | - Janos Nemeth
- Department of Ophthalmology, Semmelweis University, Faculty of Medicine, Budapest
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Evaluation of Corneal Pachymetry Measurements by Galilei Dual Scheimpflug Camera. Eur J Ophthalmol 2018; 22 Suppl 7:S33-9. [DOI: 10.5301/ejo.5000056] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2011] [Indexed: 11/20/2022]
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Repeatability and Agreement of Orbscan II, Pentacam HR, and Galilei Tomography Systems in Corneas With Keratoconus. Am J Ophthalmol 2017; 175:122-128. [PMID: 27993593 DOI: 10.1016/j.ajo.2016.12.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 12/07/2016] [Accepted: 12/07/2016] [Indexed: 11/23/2022]
Abstract
PURPOSE To assess the repeatability and agreement of keratometry and pachymetry measurements obtained using 3 tomographers in eyes with keratoconus. DESIGN Reliability analysis. METHODS setting: Institutional. STUDY POPULATION Fifty eyes of 50 participants with keratoconus. observational procedure: Steep keratometry, flat keratometry, central corneal thickness (CCT), and thinnest corneal thickness (TCT) measurements using Galilei, Orbscan II, and Pentacam HR. MAIN OUTCOME MEASURES Repeatability was assessed using within-subject standard deviation (SW), coefficient of variation (CV), and intraclass correlation coefficient (ICC). Bland-Altman plots and 95% limits of agreement (LoA) were used to evaluate agreement between device pairs. RESULTS For all studied parameters, ICC was >0.97 with the least repeatable measurements obtained using Orbscan II. Mean steep keratometry values were similar while mean flat keratometry values were significantly different between all devices. The Galilei and Pentacam HR had the lowest 95% LoA for both CCT and TCT. There were no significant differences in mean CCT between Galilei and Pentacam HR. Mean Orbscan II CCT measurements were not significantly different overall but had wide 95% LoA with Pentacam HR (-47.95 to 58.09 μm) and Galilei (-43.70 to 53.91 μm). Mean Orbscan II CCT measurements were significantly lower when an acoustic factor of 0.92 was applied (-33.6 μm vs Pentacam HR, P < .001; -33.6 μm vs Galilei; P < .001). CONCLUSIONS Keratometric and pachymetric measurements of keratoconic eyes obtained by Galilei, Orbscan II, and Pentacam were disparate. Measurements were less repeatable with Orbscan II compared with Pentacam HR and Galilei, although overall repeatability was high for all instruments.
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Kumar M, Shetty R, Jayadev C, Dutta D. Comparability and repeatability of pachymetry in keratoconus using four noncontact techniques. Indian J Ophthalmol 2016; 63:722-7. [PMID: 26632128 PMCID: PMC4705708 DOI: 10.4103/0301-4738.170987] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
PURPOSE To compare and determine the repeatability of central corneal thickness (CCT) measurements using four noncontact pachymetry instruments in eyes with keratoconus. MATERIALS AND METHODS The CCT of consecutive patients with keratoconus was measured during a single visit using the swept source optical coherence tomography (SS-OCT, Casia SS-1000°CT, Tomey, Nagoya, Japan), a rotating Scheimpflug camera system (Pentacam, Oculus Optikgerate GmbH, Wetzlar, Germany), scanning slit topographer (Orbscan IIz topography, Baush and Lomb Surgical Inc., San Dimas, CA, USA), and a hand-held spectral domain OCT (HHSD-OCT, Bioptigen Inc., Durham, North Carolina, USA). Test-retest variability, correlation between measurements and interdevice agreement were analyzed. RESULTS Fifty eyes of 25 participants were analyzed in this study. All measurement methods correlated well with each other (r > 0.9, P < 0.001). Mean ± standard deviation CCT measured by HHSD-OCT, Orbscan IIz, SS-OCT, and Pentacam was 462 ± 41 mm, 458 ± 41 mm, 454 ± 40 mm, and 447 ± 42 mm, respectively. While the HHSD-OCT over-estimated the CCT (P < 0.001), there was a good correlation between the measurements obtained from the other three devices. However, the numerical difference was high and this trend was seen in all the paired comparisons. CONCLUSIONS Though the measurements by different devices correlated well, the numerical agreement may be inadequate for their interchangeable use in clinical practice.
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Affiliation(s)
- Mukesh Kumar
- Department of Cornea and Refractive Surgery, Narayana Nethralaya Super Specialty Eye Hospital, Bengaluru, Karnataka, India
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Briggs S, Bin Moammar M. Effect of 2% fluorescein on Scheimpflug central corneal thickness measurements. Int J Ophthalmol 2016; 9:239-42. [PMID: 26949642 DOI: 10.18240/ijo.2016.02.10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 12/12/2014] [Indexed: 11/23/2022] Open
Abstract
AIM To assess central corneal thickness (CCT) changes measured with Scheimpflug device following instillation of 2% fluorescein in normal subjects. METHODS This was a prospective randomized study of 60 hospital volunteers. After baseline CCT measurements of both eyes of 40 subjects were obtained using Scheimpflug system, a drop of preservative-free 2% fluorescein, was instilled in one eye and in other eye, one drop of normal saline (control). Measurements were repeated after 1, 2, 5, 10, 20, 30, 40, 50 and 60min (continuous assessment group). Twenty subjects had baseline CCT taken, then fluorescein was instilled in one eye and measurements were taken at 1min. Ten eyes had saline rinse after 1min and 10 other eyes did not, measurements were repeated at 2min (eye rinse group). RESULTS The mean baseline CCT for continuous assessment group was 546.2 ±32.1 µm (range, 489.0-606.0), control eyes was 546.6±30.7 µm (range, 489.0-602.0). At 1min after fluorescein instillation, CCT significantly increased by 37.0±34.0 µm (P<0.001), then decreased gradually, reaching baseline at 60min. CCT variations were not significant in control group (P>0.05). For eye rinse group, CCT mean differences between baseline and 2min were 18.2 µm (95 % CI: -54.7 to 18.3) with rinse and 26.5 µm (95% CI: -62.9 to 9.9) without rinse; paired sample tests were not significant (P>0.05). CONCLUSION The presence of fluorescein increased CCT value to a clinically relevant level of 6.8%. Eye rinse did not significantly reduce the effect at 2min post fluorescein timepoint.
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Affiliation(s)
- Stella Briggs
- College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Marwa Bin Moammar
- Ophthalmology Clinic, Security Forces Hospital, Riyadh 11481, Saudi Arabia
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Rashid RF, Farhood QK. Measurement of central corneal thickness by ultrasonic pachymeter and oculus pentacam in patients with well-controlled glaucoma: hospital-based comparative study. Clin Ophthalmol 2016; 10:359-64. [PMID: 27041982 PMCID: PMC4780203 DOI: 10.2147/opth.s96318] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background The measurement of central corneal thickness (CCT) plays an important role in the diagnosis and treatment of glaucoma and many corneal diseases. Objective of the study To compare the measurement of CCT by ultrasonic pachymeter with that measured by oculus pentacam in both normal subjects and patients with well-controlled glaucoma. Patients and methods In 173 eyes of both controls and patients with open-angle glaucoma (normal intraocular pressure) attending Ibn Al Haitham Teaching Eye Hospital, CCT was measured by oculus pentacam and then by ultrasound pachymeter at the same morning by the same technicians. Results The results showed no significant difference in CCT readings measured by the two devices in both glaucoma and control groups (glaucoma group: 547.29±49.32 µm with pentacam vs 547.66±45.24 µm with ultrasound pachymeter; control group: 551.02±36.28 µm with pentacam vs 541.25±34.96 µm with ultrasound pachymeter). P-values were >0.05 in both groups (statistically not significant). Conclusion and recommendation Ultrasonic pachymeter and oculus pentacam can be used interchangeably in measuring CCT, and we recommend a nontouch method (in this study, pentacam Scheimpflug camera) for measuring CCT during assessment of patients with glaucoma or any ocular disease or surgery.
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Affiliation(s)
- Riyam Faihan Rashid
- Department of Ophthalmology, College of Medicine, University of Babylon, Babylon, Iraq
| | - Qasim K Farhood
- Department of Ophthalmology, College of Medicine, University of Babylon, Babylon, Iraq
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Measurement of central corneal thickness with optical low-coherence reflectometry and ultrasound pachymetry in normal and post-femtosecond laser in situ keratomileusis eyes. Cornea 2015; 34:204-8. [PMID: 25514702 DOI: 10.1097/ico.0000000000000329] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE To determine the repeatability and reproducibility of measurements of central corneal thickness (CCT) using optical low-coherence reflectometry (Lenstar LS900; Haag Streit) in normal eyes and post-femtosecond laser in situ keratomileusis (post-FS-LASIK) eyes and evaluate their agreement with ultrasound (US) pachymetry. METHODS CCT was measured using Lenstar and US pachymetry sequentially in normal and post-FS-LASIK eyes by 2 experienced observers. Intraoperator repeatability and interoperator reproducibility were assessed by within-subject standard deviation, test-retest repeatability, coefficient of variation (CoV), and intraclass correlation coefficient. Paired t-tests and Bland-Altman plots were used for analyzing agreement between the 2 devices. RESULTS In this study, 55 healthy subjects and 50 post-FS-LASIK patients were recruited. Test-retest repeatability of Lenstar was within 10 μm, CoV was less than 1.0%, and intraclass correlation coefficient was more than 0.9 in both normal and post-FS-LASIK groups. Mean difference between these methods was 1.4 ± 4.2 μm and -1.7 ± 5.4 μm, respectively. Moreover, measurements of CCT showed narrow 95% limits of agreement (range, normal group: -6.8 and 9.6 μm; post-FS-LASIK group: -12.4 and 8.9 μm), which implied good agreement. CONCLUSIONS Measurements of CCT using Lenstar showed excellent intraoperator repeatability and interoperator reproducibility both in normal eyes and post-FS-LASIK eyes. Measurements of CCT using Lenstar and US pachymetry showed good agreement and both can be used interchangeably.
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Ramamurthy S, Reddy JC, Jhanji V. Topography and tomography in the diagnosis of corneal ectasia. EXPERT REVIEW OF OPHTHALMOLOGY 2015. [DOI: 10.1586/17469899.2015.1044979] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Pentacam vs SP3000P specular microscopy in measuring corneal thickness. Cont Lens Anterior Eye 2014; 38:21-7. [PMID: 25240777 DOI: 10.1016/j.clae.2014.08.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 08/01/2014] [Accepted: 08/28/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare corneal thickness (CT) measurements obtained with SP3000P specular microscope and Pentacam in eyes screened to undergo refractive surgery (RS). METHODS In this prospective study, a non-randomized consecutive series of 73 healthy eyes (age range: 14-78 years; mean=38.4±14.9) underwent CT measurement with both Oculus Pentacam and Topcon SP3000P specular microscope to assess their suitability to undergo corneal RS. RESULTS CT measurements with SP3000P ranged from 451 to 609 μs (mean 523.1±34.4 μs). The measurements obtained with Pentacam ranged at the corneal apex from 477 to 672 μs (mean 558.9±38.9 μs), at the pupil center from 477 to 672 μs (mean 557.9±38.9 μs) and at the thinnest point from 474 to 669 μs (mean 551.1±39.4 μs). CT measurements showed a good correlation but a statistically significant difference at the pupil center (mean -34.9±14.6 μs, R(2)=0.860, p<0.001), at the apex (mean -35.9±14.9 μs, R(2)=0.856, p<0.001) and at the thinnest point (mean -32±14.8 μs, R(2)=0.862, p<0.001). The calculated regression formulas were: y=0.816x+66.94 for the apex, y=0.819x+66.07 for the pupil center and y=0.810x+73.13 for the thinnest point; where y is the CT measured with the SP3000P and x is the measurement obtained with the Oculus Pentacam. CONCLUSIONS Our results suggest that SP3000P measures thinner corneas compared to the Pentacam and that the correcting factor we identified should be applied to make comparisons between these two devices.
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Comparison and repeatability of keratometric and corneal power measurements obtained by Orbscan II, Pentacam, and Galilei corneal tomography systems. Am J Ophthalmol 2013; 156:53-60. [PMID: 23540708 DOI: 10.1016/j.ajo.2013.01.029] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 01/23/2013] [Accepted: 01/24/2013] [Indexed: 11/21/2022]
Abstract
PURPOSE To assess the repeatability and comparability of corneal power and central corneal thickness (CCT) measurements obtained using Orbscan II (Bausch & Lomb), Pentacam (Oculus), and Galilei (Ziemer) tomographers. DESIGN Prospective, comparative study. METHODS setting: Departments of Ophthalmology, University of Auckland and Auckland District Health Board, Auckland, New Zealand. study population: Thirty eyes of 30 healthy participants. observations. CCT and corneal power measured using Orbscan II, Pentacam, and Galilei tomography. main outcome measures: Degree of agreement in and repeatability of CCT and corneal power measures. RESULTS Orbscan II measured significantly lower CCT compared with Pentacam (20 μm; P < .0005) and Galilei (18 μm; P < .0005). The Orbscan II had wide limits of agreement when compared with both the Galilei (-11 to 47 μm) and Pentacam (-88 to 47 μm). For each device, the intraclass correlation coefficient for CCT was higher than 0.9. The coefficient of variation ranged from 0.33% to 0.93%. There was no significant difference in mean steep keratometry or mean flat keratometry between instrument pairs. However, there was poor agreement in flat keratometry and steep keratometry obtained by Orbscan II compared with those obtained by the Galilei and Pentacam. CONCLUSIONS The keratometry and pachymetry measurements obtained by Orbscan II, Pentcam, and Galilei tomographers were sufficiently disparate that the 3 devices could not be considered equivalent. All 3 devices demonstrated a high level of repeatability, although the Galilei exhibited the best repeatability.
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Fukuda R, Usui T, Miyai T, Mori Y, Miyata K, Amano S. Corneal Thickness and Volume Measurements by Swept Source Anterior Segment Optical Coherence Tomography in Normal Subjects. Curr Eye Res 2013; 38:531-6. [DOI: 10.3109/02713683.2012.745878] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Repeatability of pachymetric mapping using fourier domain optical coherence tomography in corneas with opacities. Cornea 2012; 31:418-23. [PMID: 22236789 DOI: 10.1097/ico.0b013e31823f098c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the repeatability of Fourier domain optical coherence tomography (OCT) pachymetric mapping in patients with corneal opacities and to assess the reliability of Fourier domain OCT with 830 nm wavelength as a pachymetric measurement tool in opaque corneas. METHODS A Fourier domain OCT system was used to map the corneal thickness of patients with corneal scars or dystrophy. A retrospective study of a consecutive series was conducted. The repeatability was measured using pooled standard deviation of repeated measurements. A slit-scanning tomography device provided pachymetric mapping for comparison. RESULTS Seventeen eyes of 12 patients with corneal scars (7 trauma and 3 post infection) or dystrophy (2 Reis-Bucklers and 5 granular dystrophy) were included. The posterior corneal boundary was detectable in all cases. The average corneal thickness measured by OCT was 536 ± 89 μm in central 2 mm area, 553 ± 76 μm in pericentral 2- to 5-mm area, and 508 ± 93 μm for the minimum corneal thickness. The slit-scanning tomography central corneal thickness, 433 ± 111 μm, was significantly lower than OCT readings (mean difference -91.1 ± 33.3 μm, P = 0.002). Repeatability of the OCT measurements was 2.1 μm centrally and 1.2 μm pericentrally. CONCLUSION Pachymetric mapping with Fourier domain OCT was highly repeatable. Fourier domain OCT is a reliable pachymetric tool in opaque corneas. In comparison, corneal thickness measured by the slit-scanning tomography is significantly thinner than those measured by the Fourier domain OCT in the presence of corneal opacities.
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Guilbert E, Saad A, Grise-Dulac A, Gatinel D. Corneal thickness, curvature, and elevation readings in normal corneas: Combined Placido–Scheimpflug system versus combined Placido–scanning-slit system. J Cataract Refract Surg 2012; 38:1198-206. [DOI: 10.1016/j.jcrs.2012.01.033] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 01/08/2012] [Accepted: 01/16/2012] [Indexed: 11/26/2022]
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Accuracy and Repeatability of a New Tono-Pachymeter for Measuring Central Corneal Thickness. Eye Contact Lens 2012; 38:158-63. [DOI: 10.1097/icl.0b013e31824b005b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Evaluation of central corneal thickness measurement with RTVue spectral domain optical coherence tomography in normal subjects. Cornea 2011; 30:121-6. [PMID: 20885314 DOI: 10.1097/ico.0b013e3181e16c65] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE To determine (1) repeatability of central corneal thickness (CCT) measurements by spectral domain optical coherence tomography (RTVue; Optovue, Inc, Fremont, CA) and (2) agreement between CCT measurements by RTVue and those by ultrasonic pachymetry, Orbscan, and anterior segment optical coherence tomography (ASOCT). METHODS In a prospective observational study, 2 cohorts of normal subjects were recruited. In the first cohort (51 subjects), 5 measurements of CCT were obtained by RTVue during the same visit to determine the repeatability. In the second cohort (65 subjects), CCT measurements were obtained by RTVue, ultrasonic pachymetry, Orbscan, and ASOCT during the same visit to determine the agreement among these instruments. Repeatability was assessed by intraclass correlation coefficient (ICC), within-subject standard deviation, coefficient of repeatability, and within-subject coefficient of variation. Agreement was assessed by ICC and Bland and Altman plots. RESULTS Repeatability of CCT measurements by RTVue as assessed by ICC, within-subject standard deviation, coefficient of repeatability, and within-subject coefficient of variation was 0.99 (0.99-0.99), 2.2 (1.9-2.5), 4.2 μm (3.6-4.8), and 0.4% (0.3-0.5), respectively. The average CCT by RTVue (529 μm) was comparable to that by ultrasonic pachymetry (539 μm; P = 0.15), Orbscan (536 μm; P = 0.54), and ASOCT (526 μm; P = 0.77). The 95% limits of agreement on Bland and Altman plots ranged from 20 μm (between RTVue and ASOCT) to 33 μm (between RTVue and Orbscan). CONCLUSIONS CCT measurements by RTVue have an excellent repeatability. Although CCT measurements by RTVue are comparable to that by ultrasonic pachymetry, Orbscan, and ASOCT, the difference between instruments can be significant depending on the clinical situation considered.
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Bao FJ, Yu AY, Kassem W, Wang QM, Elsheikh A. Biometry of the Cornea in Myopic Chinese Patients. J Refract Surg 2011; 27:345-55. [DOI: 10.3928/1081597x-20101105-02] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 08/31/2010] [Indexed: 11/20/2022]
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Central Corneal Thickness Measured With Three Optical Devices and Ultrasound Pachometry. Eye Contact Lens 2011; 37:66-70. [DOI: 10.1097/icl.0b013e31820c6ffc] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Sedaghat MR, Daneshvar R, Kargozar A, Derakhshan A, Daraei M. Comparison of central corneal thickness measurement using ultrasonic pachymetry, rotating Scheimpflug camera, and scanning-slit topography. Am J Ophthalmol 2010; 150:780-9. [PMID: 20932508 DOI: 10.1016/j.ajo.2010.06.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2009] [Revised: 06/03/2010] [Accepted: 06/13/2010] [Indexed: 11/30/2022]
Abstract
PURPOSE To evaluate and compare central corneal thickness measurements using rotating Scheimpflug camera, scanning-slit topography, and ultrasound pachymetry in virgin, healthy corneas. DESIGN Prospective, observational, cross-sectional study. METHODS Central corneal thickness in 157 healthy eyes of 157 patients without ocular abnormalities other than refractive errors was measured, in a sequential order, once with rotating Scheimpflug camera and scanning-slit topography and 3 times with ultrasound pachymetry as the last part of examination. All measurements were performed by a single experienced examiner. The results from scanning-slit topography are given with and without correction for "acoustic correction factor" of 0.92. RESULTS The average measurements of central corneal thickness by rotating Scheimpflug imaging, scanning-slit pachymetry, and ultrasound were 537.15 ± 32.98 μm, 542.06 ± 39.04 μm, and 544.07 ± 34.75 μm, respectively. The mean differences between modalities were 6.92 μm between rotating Scheimpflug and ultrasound (P < .0001), 2.01 μm between corrected scanning-slit and ultrasound (P = .204), and 4.91 μm between corrected scanning-slit and rotating Scheimpflug imaging (P = .001). According to Bland-Altman analysis, highest agreement was between ultrasonic and rotating Scheimpflug pachymetry. CONCLUSIONS In the assessment of normal corneas, rotating Scheimpflug topography measures central corneal thickness values with higher agreement to ultrasound pachymetry.
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Affiliation(s)
- Mohammad Reza Sedaghat
- Khatam Anbia Eye Hospital, Eye Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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Abstract
PURPOSE To evaluate the changes in central corneal thickness (CCT) and corneal volume (CV) in eyes that have undergone myopic photorefractive keratectomy (PRK). METHODS CCT and CV obtained with an Oculus Pentacam before 1, 3, and 6 months after PRK were analyzed in 84 eyes with a mean preoperative refraction of -4.93 ± 2.23 diopter. The changes were compared with the amount of refractive treatment. The differences were evaluated with the Student t test and the correlations with the Pearson index. RESULTS One month after PRK, CCT and CV mean differences were 73.2 ± 31.5 μm (P < 0.001) and 2.2 ± 1.7 mm (P < 0.001), respectively. Three months after PRK, CCT and CV mean differences were 66.6 ± 26.7 μm (P < 0.001) and 1.4 ± 1.3 mm (P < 0.001), respectively. Six months after PRK, CCT and CV mean differences were 65.3 ± 25.7 μm (P < 0.001) and 1.4 ± 1.3 mm (P < 0.001), respectively. The effective treatment at each follow-up point was correlated with CCT changes (R = 0.62, 0.71, and 0.73, respectively), but not with CV changes (R = 0.04, 0.04, and 0.01, respectively). CONCLUSIONS Our findings support the hypothesis that after myopic PRK, when a series of corneal lamellae are severed centrally, the remaining peripheral segments relax. The squeezing force on the matrix is reduced, and the distance between the lamellae expands.
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Faramarzi A, Karimian F, Jafarinasab MR, Jabbarpoor Bonyadi MH, Yaseri M. Central corneal thickness measurements after myopic photorefractive keratectomy using Scheimpflug imaging, scanning-slit topography, and ultrasonic pachymetry. J Cataract Refract Surg 2010; 36:1543-9. [DOI: 10.1016/j.jcrs.2010.03.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 03/23/2010] [Accepted: 03/29/2010] [Indexed: 10/19/2022]
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The Orbscan Acoustic (Correction) Factor for Central Corneal Thickness Measures of Normal Human Corneas. Eye Contact Lens 2010; 36:106-15. [DOI: 10.1097/icl.0b013e3181d0b604] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Park SH, Choi SK, Lee DH, Kim JH. Central Corneal Thickness Measured by Four Different Methods in Normal and Post-Femtosecond Laser-Assisted LASIK Eyes. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2010. [DOI: 10.3341/jkos.2010.51.3.320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Se Hoon Park
- Department of Ophthalmology, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea
| | - Suk Kyue Choi
- Department of Ophthalmology, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea
| | - Do Hyung Lee
- Department of Ophthalmology, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea
| | - Jin Hyoung Kim
- Department of Ophthalmology, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea
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Comparison of central corneal thickness measurements by Pentacam, noncontact specular microscope, and ultrasound pachymetry in normal and post-LASIK eyes. Saudi J Ophthalmol 2009; 23:181-7. [PMID: 23960858 DOI: 10.1016/j.sjopt.2009.10.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 08/28/2009] [Indexed: 11/22/2022] Open
Abstract
PURPOSE To compare central corneal thickness (CCT) measurements taken with Pentacam, noncontact specular microscope (NCSM), and ultrasound pachymetry (US) in normal and post-laser in situ keratomileusis (LASIK) eyes and to assess the agreement between the three devices. DESIGN Prospective clinical trial. PATIENTS AND METHODS Central corneal thickness (CCT) was measured in 94 eyes of normal volunteer and in 72 eyes of post-LASIK patients. Measurements were made with the three devices. RESULTS In normal eyes, the mean (±SD) CCT taken with Pentacam, NCSM, and US was 552.6 ± 36.8 μm, 511.9 ± 38.6 μm, and 533.3 ± 37.9 μm, respectively. The average values of CCT taken with the three instruments were significantly different. In post-LASIK eyes the mean CCT with Pentacam, NCSM, and US was 483.02 ± 6.03 μm, 450.7 ± 5.3 μm, and 469.5 ± 5.8 μm, respectively. The average values of CCT taken were significantly different for Pentacam vs. NCSM (P = 0.046) and Pentacam vs. US (P = 0.02), but not significant for NCSM vs. US (P = 0.352). The Bland and Altman method for assessing clinical agreement between 3 instruments showed that in normal eyes, the mean values and paired differences of the three CCT devices were found to be statistically independent. In post-LASIK eyes, there was significant association between the difference and the mean of the Pentacam and NCSM, and US and NCSM. CONCLUSION The three devices cannot be used interchangeably in normal and post-LASIK eyes. Pentacam tends to give significantly thicker reading than ultrasound pachymetry.
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López-Miguel A, Nieto JC, Díez-Cuenca M, Piñero DP, Maldonado MJ. Agreement of non-contact pachymetry after LASIK: comparison of combined scanning-slit/Placido disc topography and specular microscopy. Eye (Lond) 2009; 24:1064-70. [PMID: 19786958 DOI: 10.1038/eye.2009.233] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To assess the interchangeability of central corneal thickness (CCT) measurements between combined scanning-slit/Placido disc topography (Orbscan-II) and specular microscopy (Topcon SP-2000P) in patients who underwent laser in situ keratomileusis (LASIK) for myopia. PATIENTS AND METHODS We recruited 118 consecutive patients who underwent LASIK for myopia. The CCT was measured using Orbscan-II and Topcon SP-2000P randomly. Orbscan-II and Topcon SP-2000P CCT data were analysed using the paired-sample t-test and the limits of agreement (LoA) were calculated with the method described by Bland-Altman. RESULTS The average CCT measurements by Orbscan-II and Topcon SP-2000P were 447.55+/-49.78 microm and 461.38+/-35.35 microm, respectively (P<0.0001; mean difference, 13.83+/-22.31 microm; 95% confidence interval, 9.77-17.09 microm). The Bland-Altman plot showed an inverse association between the average and the difference between the devices: Topcon-Orbscan-II=174.23 -0.353xAverage (P<0.01). The widths of the crude and regression-based 95% limits of agreement were 87.45 and 63.72 microm, respectively. CONCLUSIONS Orbscan-II measurements of CCT after myopic LASIK were significantly lower than those obtained using Topcon SP-2000P. The limits of agreement between the two devices were too broad and, therefore, both pachymetric values cannot be used interchangeably. Further, the tendency towards comparably Orbscan-II readings in thinner corneas precludes that one technique can directly replace the other. This is important for the adequate medium- and long-term follow-up of the growing LASIK patient population.
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Affiliation(s)
- A López-Miguel
- Departamento de Oftalmología, Clínica Universitaria, Universidad de Navarra, Pamplona, Spain.
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Basmak H, Sahin A, Yildirim N. The Reliability of Central Corneal Thickness Measurements by Ultrasound and by Orbscan System in Schoolchildren. Curr Eye Res 2009; 31:569-75. [PMID: 16877265 DOI: 10.1080/02713680600801115] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To compare the central corneal thickness measurements obtained by ultrasound (US) pachymetry and the Orbscan II system in healthy schoolchildren. METHODS A total of 356 schoolchildren aged 7 to 12 years underwent central cornal thickness (CCT) measurement with Orbscan II and ultrasonic pachymetry. All eyes were examined first with the Orbscan II and then by US pachymetry. The mean of the difference, standard deviation (SD), and 95% limits of agreement, with and without applying the acoustic correction factor, were determined. The differences between the devices in measuring mean CCT were calculated with paired-sample t test. Pearson correlation test was used to determine the correlation between variables. p < 0.05 was considered to be statistically significant. Linear regression analysis was used to quantify the correlation between the two methods. RESULTS Orbscan II measurements were significantly higher than US pachymetry measurements without applying the manufacturer-recommended acoustic correction factor (0.92) correction (580.39 +/- 37 microm and 562.95 +/- 32 microm, respectively) (p < 0.0001). When this acoustic correction factor was applied, the Orbscan II measurements demonstrated significantly lower results when compared with those of US pachymetry (533.96 +/- 34 microm and 562.95 +/- 32 microm, respectively) (p < 0.0001). The linear regression analysis lines showed approximately 45-degree slope indicating a strong correlation between these methods (US pachymetry = 145.71 + 0.72 x Orbscan II value without acoustic correction factor (microm), r = 0.89, p < 0.0001). There was a high degree of variability in differences between the 2 devices in individual subjects. The range was between 25 to -55 microm without the acoustic correction factor and 67 to -5 microm with the acoustic correction factor. CONCLUSIONS Although US pachymetry and Orbscan II demonstrated a strong linear correlation, there was a high degree of variability in differences between the two devices in individual subjects who participated.
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Affiliation(s)
- Hikmet Basmak
- Department of Ophthalmology, Eskisehir Osmangazi University Hospital, Eskisehir, Turkey.
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Fukuda S, Kawana K, Yasuno Y, Oshika T. Anterior ocular biometry using 3-dimensional optical coherence tomography. Ophthalmology 2009; 116:882-9. [PMID: 19410946 DOI: 10.1016/j.ophtha.2008.12.022] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 11/04/2008] [Accepted: 12/05/2008] [Indexed: 10/20/2022] Open
Abstract
PURPOSE To evaluate anterior ocular biometry by comparing the measurements of central corneal thickness (CCT) and anterior chamber depth (ACD) with 3-dimensional corneal and anterior segment optical coherence tomography (CAS-OCT) and other methods. DESIGN Cross-sectional study. PARTICIPANTS Forty eyes of 40 normal subjects. METHODS The CCT was measured by 4 methods (CAS-OCT, Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry), and the ACD was measured by 3 methods (CAS-OCT, Scheimpflug camera, and scanning-slit topography). The anterior chamber volume (ACV) was calculated with CAS-OCT. Repeatability and reproducibility of CAS-OCT measurements were evaluated. MAIN OUTCOME MEASUREMENTS The CCT and ACD were measured and compared between devices. The ACV was calculated with CAS-OCT. Coefficient of variation and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility of CAS-OCT measurements. RESULTS The mean CCT was 547.0+/-39.0, 590.0+/-39.8, 525.0+/-45.0, and 545.0+/-40.3 microm with CAS-OCT, Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry, respectively. Significant differences were observed among the 4 methods (P<0.0001; 1-way analysis of variance [ANOVA]). The CCT measured with Scheimpflug camera was significantly larger than those measured with the other methods (P<0.0001; Bonferroni multiple comparison), but there was no significant difference among the other 3 methods. The mean ACD was 3.01+/-0.47, 3.04+/-0.52, and 2.88+/-0.50 mm with CAS-OCT, Scheimpflug camera, and scanning-slit topography, respectively. There was no significant difference among the 3 methods (P = 0.678; 1-way ANOVA). A significant linear correlation in CCT and ACD were observed between CAS-OCT and other methods (all P<0.0001). The mean ACV calculated with CAS-OCT was 169.7+/-23.1 mm(3). The coefficient of repeatability and reproducibility of CCT and ACD measurements were <5% and ICCs were >0.98. CONCLUSIONS The CCT measurements were comparable among CAS-OCT, ultrasonic pachymetry, and scanning-slit topography, but Scheimpflug camera yielded a significantly higher CCT value. There was no significant difference in ACD measurements among CAS-OCT, Scheimpflug camera, and scanning-slit topography. The ACV was noninvasively measured by CAS-OCT. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any materials discussed in this article.
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Affiliation(s)
- Shinichi Fukuda
- Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki, Japan.
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Pentacam and Orbscan II Measurements ofPosterior Corneal Elevation Before andAfter Photorefractive Keratectomy. J Refract Surg 2009; 25:290-5. [DOI: 10.3928/1081597x-20090301-09] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Repeatability of Central Corneal Thickness Measures by Orbscan Pachymetry for Right and Left Eyes. Eye Contact Lens 2009; 35:20-5. [DOI: 10.1097/icl.0b013e318192d89a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
PURPOSE To measure corneal and epithelial thickness across four meridians using Optical Coherence Tomography (OCT) and to compare these measurements between normal non-lens wearers (NLW), rigid gas permeable (RGP) lens wearers, and RGP-wearing keratoconics (KC). METHODS Both eyes of 60 subjects were measured (20 NLW, nine female:11 male, 27.6 +/- 5.9 years; 20 RGP, 20 female, 23.9 +/- 7.6 years; and 20 KC, seven female:13 male, 32.4 +/- 8.1 years). A customized fixation target employing LEDs in eight directions of gaze was attached to the OCT and corneal images obtained. Raw OCT scans were analyzed to yield values for corneal and epithelial thickness and color-coded maps were compiled. RESULTS Central corneal thickness (CCT) was thinnest in KC (447 +/- 68 microm) and similar between RGP (518 +/- 32 microm; pKC < 0.001) and NLW (517 +/- 21 microm) (p(KC) < 0.001 NLW pRGP > 0.05). Peripheral corneal thickness in NLW was thickest in the superior temporal and thinnest in the inferior (I) regions (superior temporal(thickest) vs. I(thinnest) p < 0.001). Central epithelial thickness was thinnest in KC (44 +/- 7 microm), followed by RGP (50 +/- 4 microm), then NLW (54 +/- 2 microm) (pKC < 0.001 NLW p(RGP) < 0.05). Central epithelial thickness in the KC group was significantly thinner than in the RGP group (p < 0.001). In the NLW group, peripheral epithelial thickness was thicker (63 +/- 5 microm) than central (p < 0.001) and was thickest in the superior (S) region and thinnest in the inferior (I) region (S(thickest) vs. I(thinnest) p < 0.001). KC epithelium was thinnest in the inferior temporal meridian (42 +/- 5 microm). CONCLUSIONS Thickness of the normal cornea and epithelium was greatest in the superior region. In all groups, the inferior cornea and epithelium was thinnest, and to a greater extent in the KC group.
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Paul T, Lim M, Starr CE, Lloyd HO, Coleman DJ, Silverman RH. Central corneal thickness measured by the Orbscan II system, contact ultrasound pachymetry, and the Artemis 2 system. J Cataract Refract Surg 2008; 34:1906-12. [PMID: 19006737 DOI: 10.1016/j.jcrs.2008.07.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Accepted: 07/23/2008] [Indexed: 12/01/2022]
Abstract
PURPOSE To compare central corneal thickness (CCT) measurements by the Orbscan II device, contact ultrasound (US) pachymetry, and the noncontact Artemis 2 scanning US system. SETTING Department of Ophthalmology, Weill Cornell Medical College, New York, New York, USA. METHODS The CCT in 40 eyes (20 normal subjects) was measured by the Orbscan II followed by contact US pachymetry and then the Artemis 2. Results were compared using analysis of variance (ANOVA), paired t tests, and Bland-Altman plots. RESULTS There was a significant difference in CCT measurements between the 3 modes (F = 32.84, P = .0001, 1-way ANOVA). Artemis 2 and US pachymetry measurements were highly correlated (r2 = 0.963, P < .0001), although Artemis 2 values were a mean of 11.2 microm +/- 6.6 (SD) thinner than pachymetry values. Artemis 2 and Orbscan II measurements were less well correlated (r2 = 0.851, P < .001); Orbscan II values were a mean of 7.5 +/- 15.7 microm thinner than Artemis 2 values. Orbscan II values showed a trend toward increasing underestimation of CCT in thinner corneas. CONCLUSIONS Ultrasound pachymetry and Artemis 2 CCT measurements were highly correlated; the 11 microm mean difference in measurements may be attributed to decentration, oblique incidence of the probe to the cornea, or possibly the effect of topical anesthesia with contact pachymetry. Although the mean difference between Orbscan II and Artemis 2 values was 7.5 microm, Orbscan values were less correlated than Artemis 2 values with contact US pachymetry and were prone to underestimation of the CCT in thinner corneas.
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Affiliation(s)
- Tania Paul
- Department of Ophthalmology, Weill Cornell Medical College, New York Presbyterian Hospital, New York, New York 10065, USA
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Abstract
PURPOSE To compare central and peripheral corneal swelling with high-Dk (lotrafilcon A) and low-Dk (etafilcon A) contact lenses (CLs) during extended wear (EW). METHODS Corneal thickness was measured in 5 corneal locations (central, superior, inferior, nasal, and temporal) with Orbscan II pachymetry 1 week before the wearing of CLs and after 1 week of EW. High-Dk (lotrafilcon A) and low-Dk (etafilcon A) soft CLs were randomly fitted for EW in the right and left eyes of 20 subjects with normal ocular health. Orbscan was also performed before CL removal after 3 and 7 days of EW. RESULTS Lotrafilcon A induced a lower percentage of corneal swelling in all 5 corneal locations than etafilcon A (P < 0.05, paired t test). Lotrafilcon A swelling percentages were as follows: central (1.67% +/- 2.22%), superior (2.04% +/- 3.25%), inferior (1.38% +/- 1.74%), nasal (1.50% +/- 2.00%), and temporal (1.27% +/- 1.47%). Etafilcon A swelling percentages were as follows: central (4.98% +/- 3.07%), superior (6.62% +/- 8.39%), inferior (5.24% +/- 5.54%), nasal (3.41% +/- 3.14%), and temporal (4.46% +/- 3.32%). Differences between the central and peripheral corneal swelling during EW of both types of lenses were not significant (P > 0.05, repeated-measures analysis of variance). CONCLUSIONS Central and peripheral corneal thicknesses increase more with etafilcon A than with lotrafilcon A during EW, as measured by Orbscan pachymetry.
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Comparison and reproducibility of corneal thickness and curvature readings obtained by the Galilei and the Orbscan II analysis systems. J Cataract Refract Surg 2008; 34:1742-7. [DOI: 10.1016/j.jcrs.2008.06.024] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 06/04/2008] [Indexed: 11/17/2022]
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Al-Mezaine HS, Al-Amro SA, Kangave D, Sadaawy A, Wehaib TA, Al-Obeidan S. Comparison between central corneal thickness measurements by oculus pentacam and ultrasonic pachymetry. Int Ophthalmol 2008; 28:333-8. [PMID: 17898935 DOI: 10.1007/s10792-007-9143-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Accepted: 08/23/2007] [Indexed: 11/26/2022]
Abstract
PURPOSE To compare the accuracy of central corneal thickness (CCT) measurements by the oculus pentacam scheimpflug system, with those obtained with the DGH ultrasound pachymeter (UP) and to assess the agreement between the two devices. METHODS In a prospective study, measurement agreement was assessed in 984 eyes of 492 healthy subjects using both oculus pentacam and ultrasonic pachymetry at the Eye Consultants Center, Riyadh, Saudi Arabia. RESULT In the measurement agreement experiment, the mean CCT was 552.4 +/- 37.0 microm with oculus pentacam and 544.1 +/- 35.4 microm with ultrasonic pachymetry. Regression analysis showed a high correlation between the values obtained with both devices (r = 0.912, P < 0.001). Compared with UP, pentacam overestimated the CCT by a mean of 8.2 microm as demonstrated in a Bland-Altman plot. CONCLUSION the CCT measurements by the pentacam and UP are highly correlated. The pentacam agrees well with UP and is a reliable alternative to UP in CCT measurements.
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Affiliation(s)
- Hani S Al-Mezaine
- Department of Ophthalmology, College of Medicine, King Saud University, PO Box 230387, Riyadh, 11321, Saudi Arabia.
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Wang JC, Bunce C, Lee HM. Intraoperative corneal thickness measurement using optical coherence pachymetry and corneo-gage plus ultrasound pachymetry. J Refract Surg 2008; 24:610-4. [PMID: 18581787 DOI: 10.3928/1081597x-20080601-10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Jenn-Chyuan Wang
- Department of Ophthalmology, National University Hospital, Singapore.
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Matsuda J, Hieda O, Kinoshita S. Comparison of central corneal thickness measurements by Orbscan II and Pentacam after corneal refractive surgery. Jpn J Ophthalmol 2008; 52:245-249. [DOI: 10.1007/s10384-008-0550-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Accepted: 01/24/2008] [Indexed: 10/21/2022]
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Sarunic MV, Asrani S, Izatt JA. Imaging the ocular anterior segment with real-time, full-range Fourier-domain optical coherence tomography. ACTA ACUST UNITED AC 2008; 126:537-42. [PMID: 18413525 DOI: 10.1001/archopht.126.4.537] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We have demonstrated a novel Fourier-domain optical coherence tomography system and signal-processing algorithm for full-range, real-time, artifact-free quantitative imaging of the anterior chamber. Cross-sectional full-range images comprising 1024 x 800 pixels (axial x lateral) were acquired and displayed at 6.7 images/s. Volumetric data comprising 1024 x 400 x 60 pixels (axial x lateral x elevation) were acquired in 4.5 seconds with real-time visualization of individual slices and 3-dimensional reconstruction performed in postprocessing. Details of the cornea, limbus, iris, anterior lens capsule, trabecular meshwork, and Schlemm's canal were visualized. Quantitative surface height maps of the corneal epithelium and endothelium were obtained from the volumetric data and used to generate corneal thickness maps.
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Affiliation(s)
- Marinko V Sarunic
- Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Durham, North Carolina 27708, USA
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Identifying relationships between tomography-derived corneal thickness, curvature, and diameter and in vivo confocal microscopic assessment of the endothelium in healthy corneas of young adults. Eye (Lond) 2008; 23:270-8. [PMID: 18259207 DOI: 10.1038/sj.eye.6703091] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Despite the importance of a healthy endothelial layer in anterior segment surgery, the possible influence of corneal parameters on endothelial cell density (ECD) has largely been ignored in the young adult eye. This study investigated the possible associations between corneal tomographic parameters and ECD values in young adults. METHODS Subjects aged 21-30 years, with normal corneas were recruited. Mean ECD, mean cell area (MCA), coefficient of variation for cell area (COVA), and proportion of hexagonal cells were derived by in vivo confocal microscopy. The Orbscan II system was used to measure corneal parameters including: thickness, horizontal corneal diameter, corneal curvature, anterior and posterior elevation, and eccentricity. RESULTS Sixty-two subjects (42 female, 20 male) were included (mean age 25+/-3 years). Overall mean ECD was 3169+/-309 cells/mm(2) with no differences between genders. Mean percentage of hexagonality was 53+/-5%, male subjects (55%) had a higher percentage of hexagonal cells than female subjects (51%) (P=0.02). Central corneal thickness (CCT) was 529+/-43 microm. Central ECD was significantly correlated with CCT (Pearson's r=0.26, P=0.04). However, horizontal corneal diameter (r=0.19, P=0.14), anterior corneal curvature (r=-0.07, P=0.6), and posterior corneal curvature (r=-0.07, P=0.6) were not correlated with ECD or percentage of hexagonality. There was no statistically significant association between anterior chamber depth (3.6+/-0.3 mm) and ECD (r=0.15, P=0.3). CONCLUSION Corneal thickness is related to ECD in normal young adult eye, with lower ECD values identified in thinner corneas; however, corneal diameter and corneal curvature do not have a significant correlation with ECD.
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Sohajda Z, Papp J, Berta A, Módis L. The comparative study of two recently developed A-scan devices: determination of central corneal thickness, anterior chamber depth and axial length. Acta Ophthalmol 2008; 86:45-8. [PMID: 17651470 DOI: 10.1111/j.1600-0420.2007.00994.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
PURPOSE The clinical use and comparison of two recently developed A-scan ultrasound devices. METHODS The same investigator determined central corneal thickness (CCT), anterior chamber depth (ACD) and axial length (AL) with an OcuScan RxP (Alcon, Forth Worth, Texas, USA) and an AL-2000 (Tomey, Erlangen, Germany) ultrasound device in 80 eyes of 40 patients. The mean patient age was 63.72 years [standard deviation (SD) 18.92]. The patients did not suffer from any systemic or eye disease affecting the anterior and posterior segments of the eye, and their refractive error (spherical and astigmatic) did not exceed +/- 3.0 dioptres. RESULTS The value of the CCT was 541.55 (SD 34.97) microm with the OcuScan RxP, and 547.46 (SD 35.70) microm with the AL-2000 device (P < 0.001). With respect to the ACD and AL, significantly lower values were obtained with the AL-2000 instrument (P < 0.001). The ACD was 2.92 (SD 0.48) mm with the AL-2000 and 3.07 (SD 0.47) mm with the OcuScan RxP device. The AL was 22.67 (SD 0.84) mm with the AL-2000 and 22.81 (SD 0.87) mm with the OcuScan RxP instrument. However, a positive and significant correlation could be demonstrated between the devices (r = 0.88 CCT, r = 0.86 ACD and r = 0.91 AL; P < 0.001). CONCLUSION The instruments are reliable in clinical use; however, statistically significant differences were found between the devices. During patient follow-up, the devices cannot simply be used interchangeably.
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Affiliation(s)
- Zoltán Sohajda
- Department of Ophthalmology, Medical and Health Science Centre, University of Debrecen, Hungary.
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Comparison of corneal thickness measurements by ultrasound and scheimpflug photography in eyes that have undergone laser in situ keratomileusis. Am J Ophthalmol 2008; 145:75-80. [PMID: 17988643 DOI: 10.1016/j.ajo.2007.08.026] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2007] [Revised: 08/20/2007] [Accepted: 08/21/2007] [Indexed: 11/23/2022]
Abstract
PURPOSE To compare two methods of measuring central cornea thickness (CCT) in eyes that have undergone laser in situ keratomileusis (LASIK). DESIGN Prospective clinical trial. METHODS The corneal thickness from 104 eyes of 53 consecutive patients undergoing the one-year follow-up after LASIK was measured with both the Pentacam (Oculus, Inc, Wetzlar, Germany) and ultrasonic pachymetry. All patients were examined at one clinical setting, where first Pentacam imaging was performed by one technician and then ultrasound pachymetry was performed by a masked second technician. The results were compared. RESULTS The average age of the patient population was 38 years (range, 22 to 56 years) of those who underwent the one-year follow-up examination an average of 406 days (range, 264 to 579 days) after LASIK. The mean CCT measurement was 506 +/- 29.5 microm (range, 454 to 574 microm) with the Pentacam topographer and 505 +/- 31.7 microm (range, 433 to 576 microm) with ultrasound pachymetry. The average difference (Pentacam minus ultrasound) was 1.4 +/- 10.4 microm (range, -21.8 to 23.4 microm). CONCLUSIONS The Pentacam's CCT measurement and that of ultrasound pachymetry show good correlation. Pentacam pachymetry may be substituted for ultrasound in the post-LASIK patient.
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Sandler SF, Zelefsky JR, Dorairaj S, Arthur SN, Ritch R, Liebmann JM. Intra-Observer and Inter-Observer Reliability and Reproducibility of Slit-Lamp–Adapted Optical Coherence Tomography for Evaluation of Anterior Chamber Depth and Central Corneal Thickness. Ophthalmic Surg Lasers Imaging Retina 2008; 39:299-303. [DOI: 10.3928/15428877-20080701-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hashemi H, Roshani M, Mehravaran S, Parsafar H, Yazdani K. Effect of corneal thickness on the agreement between ultrasound and Orbscan II pachymetry. J Cataract Refract Surg 2007; 33:1694-700. [PMID: 17889762 DOI: 10.1016/j.jcrs.2007.05.036] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Accepted: 05/27/2007] [Indexed: 11/23/2022]
Abstract
PURPOSE To study the agreement between ultrasound (US) and Orbscan II (Bausch & Lomb) measurements with different ranges of central thickness in normal corneas. SETTING Noor Ophthalmology Research Center, Tehran, Iran. METHODS The central corneal thickness was measured first by the Orbscan II and then with a US pachymeter in 177 right eyes. Data were compared in 3 thickness groups: less than 500 microm, 500 to 600 microm, and more than 600 microm. In all cases, uncorrected Orbscan II data were used. For each range, a correction factor was calculated through regression analysis, which was then used in a new set of analyses. To study the agreement between the 2 methods, the 95% limits of agreement (LoA) and intraclass correlations coefficients (ICC) were determined. RESULTS The mean interdevice difference was 2.7 +/- 16.9 (SD) in the less than 500 microm group (P = .365), 21.3 +/- 3.1 in the 500 to 600 microm group (P = .0001), and 27.2 +/- 20.9 in the more than 600 microm group (P = .0001). No clinically acceptable LoA were found in any group. The application of regression equations to the Orbscan II readings improved the agreement in the less than 500 microm group better than the other 2 groups. The ICC was 0.76, 0.61, and 0.43 in the less than 500 microm, 500 to 600 microm, and more than 600 microm groups, respectively. CONCLUSIONS The Orbscan corneal thickness readings had relatively lower validity than US measurements. The 2 devices should not be used interchangeably, especially when the validity of the measurement is vital. In patient screening for corneal surgery, it is advisable to recheck corneal thickness with a US pachymeter.
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Affiliation(s)
- Hassan Hashemi
- Noor Ophthalmology Research Center, Tehran University of Medical Sciences, Tehran, Iran
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