Corneal thickness measurements in normal and keratoconic eyes: Pentacam comprehensive eye scanner versus noncontact specular microscopy and ultrasound pachymetry

Uçakhan, Ömür Ö.; Özkan, Mehmet; Kanpolat, Ayfer

doi:10.1016/j.jcrs.2006.02.037

Cited by 165 publications

(110 citation statements)

References 23 publications

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“…Logistic regression was used to support the cutoff point identified with the ROC curve analysis. (5)(6)(7)(8)(9)(10)(11)(12)(13)(14) . However, accurate differentiation of keratoconus from healthy corneas is not yet sufficient, as there is a need to detect corneas with a higher susceptibility to becoming ectatic after laser photoablative surgery (15)(16) .…”

Section: Ability Of Corneal Biomechanical Metrics and Anterior Segmenmentioning

confidence: 99%

Ability of corneal biomechanical metrics and anterior segment data in the differentiation of keratoconus and healthy corneas

Fontes¹,

Ambrósio²,

Jardim³

et al. 2010

Arq. Bras. Oftalmol.

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Purpose: To evaluate the sensitivity, specificity, and test accuracy of corneal biomechanical metrics and anterior segment data in differentiating keratoconus from healthy corneas. Methods: Comparative case series. Patients with and without keratoconus (gender and age-matched) were submitted for complete eye examinations including corneal hysteresis (CH) and corneal resistance factor (CRF) as measured by the Ocular Response Analyzer and anterior segment data as gathered through Pentacam assessments. The anterior segment data measurement included average central keratometric readings (K-Ave), corneal astigmatism (CA), central corneal thickness (CCT), anterior chamber depth (AC depth) and corneal volume (CV). All parameters were assessed, compared and analyzed. A receiver operating characteristic (ROC) curve was used to identify the best cutoff point by which to maximize the sensitivity and specificity of discriminating keratoconus from normal corneas for each data category. Results: Seventy seven eyes from forty three patients (24 male, 19 female) with keratoconus and eighty six eyes from forty three (24 male, 19 female) healthy controls were enrolled. ROC curve analysis showed poor overall predictive accuracy for all studied parameters in differentiating keratoconus from normal corneas. The highest sensitivity (79.2%) was obtained for both AC depth and CH (cutoff points 3.22 mm and 9.39 mmHg respectively). The best specificity (89.5%) and test accuracy (80.34%) were obtained for CA (cutoff point of 2.2 D). Conclusion: When considered together, studied parameters showed statistical differences between groups. However, when considered independently they presented low sensitivity, specificity and test accuracy in differentiating keratoconus from healthy corneas. Keywords: Cornea; Corneal diseases; Corneal topography; Biomechanics; Keratoconus. RESUMOObjetivo: Avaliar a sensibilidade, especificidade e acurácia de parâmetros biomecânicos e anatômicos do segmento anterior isolados na diferenciação de córneas saudáveis e com ceratocone. Métodos: Estudo tipo série de casos comparativa. Pacientes com ceratocone e controles saudáveis foram pareados (idade e sexo) e submetidos a exame oftalmológico completo, incluindo avaliação biomecânica (ORA) e tomográfica (Pentacam). Ceratometria central média, astigmatismo corneano, espessura corneana central, profundidade da câmara anterior, volume corneano, CH e CRF foram estabelecidos, avaliados e comparados. Curvas ROC (Receiver operating characteristic) foram utilizadas para identificar o melhor valor de corte que apresentasse a maior sensibilidade e especificidade na discriminação entre ceratocone e córneas saudáveis para cada dado estudado. Resultados: Setenta e sete olhos de 43 pacientes com ceratocone (24 homens e 19 mulheres) e 86 olhos de pacientes saudáveis (24 homens e 19 mulheres) foram incluídos no estudo. Curvas ROC mostraram baixa acurácia na predição do diagnóstico de ceratocone em todos os parâmetros isolados estudados. Maior sensibilidade encontrada foi 79,...

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Section: Ability Of Corneal Biomechanical Metrics and Anterior Segmenmentioning

confidence: 99%

Ability of corneal biomechanical metrics and anterior segment data in the differentiation of keratoconus and healthy corneas

Fontes¹,

Ambrósio²,

Jardim³

et al. 2010

Arq. Bras. Oftalmol.

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“…However, proper patient selection is challenging in such cases, as preoperative thin corneas and thinner residual stromal bed after excimer laser ablation are widely described as risk factors for the development of postoperative ectasia (3)(4) . Healthy patients can present with thin corneas (≤505 μm), and keratoconic eyes can have a "normal" (≤520 μm) central corneal thickness (CCT) (5)(6)(7)(8) . For decision making in these cases, the surgeon should rely on analysis of corneal topography and tomography data (such as corneal volume, elevation maps and pachymetric distribution) (9)(10) .…”

Section: Introductionmentioning

confidence: 99%

Corneal biomechanical evaluation in healthy thin corneas compared with matched keratoconus cases

Fontes¹,

Ambrósio²,

Velarde³

et al. 2011

Arq. Bras. Oftalmol.

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Purpose: To evaluate and compare corneal hysteresis (CH) and corneal resistance factor (CRF) in healthy eyes with a central corneal thickness (CCT) ≤ 505 μm with CH and CRF in gender-, age-, and CCT-matched keratoconus cases, and to estimate the sensitivity and specificity of these parameters for discriminating between the two groups. Methods: Prospective, comparative case series. In total 46 eyes from 30 healthy patients with CCT ≤ 505 μm, and 42 eyes from 30 CCT-, gender-and age-matched keratoconus cases were enrolled. Biomechanical metrics (CH and CRF) were measured using the Ocular Response Analyzer (ORA) and then compared. A receiver operating characteristic (ROC) curve was used to identify cut-off points to maximize the sensitivity and specificity for discriminating between the groups. Results: The CCT was 485.96 ± 17.61 μm (range, 438 -505) in healthy thin corneas and 483.64 ± 16.19 μm (range, 452 -505) in keratoconus; p=0.5225. CH was 8.63 ± 1.23 mmHg (range, 5.95 -12.2) and 8.07 ± 1.17 mmHg (range, 4.9 -9.85), respectively; p=0.0312. CRF was 8.43 ± 1.29 mmHg (range, 5.45 -11.10) and 7.22 ± 1.34 mmHg (range, 4.7 -9.45), respectively; p<0.001. ROC curve analysis showed a poor overall predictive accuracy of CH (cut-off, 8.95 mmHg; sensitivity, 63%; specificity, 23.8%; test accuracy, 44.30%) and CRF (cut-off, 7.4 mmHg; sensitivity, 28.3%; specificity, 40.5%; test accuracy, 34.12%) for detecting keratoconus in the eyes studied. Conclusion: CH and CRF were statistically lower in keratoconus than in healthy thin corneas. However, CH and CRF offered very low sensitivity and specificity for discriminating the groups.Keywords: Cornea/physiology; Keratoconus; Corneal diseases; Biomechanics/physiology; Diagnostic techniques, ophthalmological RESUMOObjetivo: Avaliar e comparar a histerese corneana (CH) e o fator de resistência corneano (CRF) em olhos saudáveis com espessura corneana central (CCT) ≤ 505 μm com os resultados de CH e CRF em pacientes com ceratocone pareados por sexo, idade e CCT, além de estimar a sensibilidade e especificidade destes parâmetros na diferenciação dos grupos. Métodos: Estudo prospectivo, do tipo série de casos comparativa. No total, 46 olhos de 30 pacientes saudáveis com CCT ≤ 505 μm, e 42 olhos de 30 pacientes com ceratocone pareados por sexo, idade e CCT foram incluídos. Os parâmetros biomecânicos (CH e CRF) foram obtidos através do equipamento Ocular Response Analyzer (ORA) e depois comparados. Curvas ROC (Receiver operating characteristic) foram utilizadas para identificar o melhor valor de corte que apresentasse a maior sensibilidade e especificidade na discriminação entre ceratocone e córneas finas saudáveis para cada dado estudado. Resultados: A CCT encontrada foi 485,96 ± 17,61 μm (de 438 a 505) no grupo de córneas finas saudáveis e 483.64 ± 16,19 μm (de 452 a 505) no grupo ceratocone; p=0,5225. CH 8,63 ± 1,23 mmHg (de 5,95 a 12,2) e 8,07 ± 1,17 mmHg (de 4,9 a 9,85), respectivamente; p=0,0312. CRF 8,43 ± 1,29 mmHg (de 5,45 a 11,10) e 7,22 ± 1,34 mmHg (de 4,7 a 9,45), resp...

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“…Corneal thickness has been proposed to be a useful parameter for the clinical identification of keratoconus. 36,37 Studies using ultrasound 38,39 or slit-scanning technologies40 have found that the difference (or ratio) between the peripheral and the thinnest (or central) corneal thickness was significantly greater in eyes with keratoconus than in normal eyes. Corneal thickness measurements have some disadvantages.…”

Section: Discussionmentioning

confidence: 99%

Keratokonus ve Subklinik Keratokonusun Tespit Edilmesi için Pentacamla Korneal Hacim Ölçümleri

Çağıl¹,

Uğurlu²,

Çakmak³

et al. 2013

Tjo

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Sum maryPur po se: To estimate the sensitivity and specificity of corneal volume (CV) measurements in discriminating keratoconus and subclinical keratoconus from normal corneas. Ma te ri al and Met hod: Clinical records and Pentacam measurements of ninety-four patients with keratoconus, 36 patients with subclinical keratoconus, and 166 refractive surgery candidates with normal corneas were evaluated retrospectively. CV within 3, 5, 7, and 10 mm circles around the central cornea was measured in one eye of each patient, using the Pentacam. CV measurements in keratoconus and subclinical keratoconus were compared with normal corneas. Receiver operating characteristic (ROC) curves were used to determine the test's overall predictive accuracy and to identify optimal CV cutoff points to maximize sensitivity and specificity in discriminating keratoconus and subclinical keratoconus from normal corneas. Re sults: Mean CV within a 3.0 mm circle around the central cornea was statistically lower in keratoconus (3.4±0.2 mm 3 , p<0.001) and subclinical keratoconus (3.6±0.2mm 3 , p<0.001) versus normal corneas (3.8±0.3mm 3 ). ROC curve analysis showed high overall predictive accuracy of CV for keratoconus (area under the curve 0.92). Optimal cutoff points were 3.55 mm 3 for keratoconus and 3.65 mm 3 for subclinical keratoconus. These values provided sensitivity and specificity of 83% and 86%, respectively, for keratoconus, and 61% and 74% for subclinical keratoconus. Dis cus si on: CV within a 3.0 mm circle around the central cornea effectively discriminates keratoconus from normal corneas. However, its sensitivity and specificity are lower for subclinical keratoconus diagnosis. (Turk J Ophthalmol 2013; 43: 77-82) Key Words: Corneal volume, keratoconus, pentacam, subclinical keratoconus Özet Amaç: Kornea hacmi (KH) ölçümlerinin keratokonus ve subklinik keratokonusu normal kornealardan ayırt etmedeki duyarlılık ve özgünlüğünün tespit edilmesi. Ge reç ve Yön tem: Doksan dört keratokonus hastası, 36 subklinik keratokonuslu hasta ve 166 refraktif cerrahi adayının klinik kayıtları ve Pentacam ölçümleri retrospektif olarak incelendi. Pentacam kullanarak her hastanın santral kornea etrafındaki 3, 5, 7 ve 10 mm lik dairelerdeki KH'sı ölçüldü. Keratokonus ve subklinik keratokonustaki KH ölçümleri normal kornealarla karşılaştırıldı. Testin tüm tahmini doğruluğunu test etmek ve keratokonus ve subklinik keratokonusu normal kornealardan ayırt etmekte duyarlılık ve özgünlüğü maksimuma çıkaran optimal kesim noktalarının tanımlamak için ROC (Receiver operating characteristic) eğrileri kullanıldı. Sonuçlar: Santral kornea etrafındaki 3,0 mm'lik dairedeki KH; keratokonusta (3,4±0,2mm 3 , p<0,001) ve subklinik keratokonusta (3,6±0,2mm 3 , p<0,001) normal kornealara gore (3,8±0,3 mm 3 ) istatistiksel olarak düşüktü. ROC eğrisi analizi KH'nın keratokonus için yüksek toplam tahmini doğruluğunu gösterdi ( eğri altında kalan alan 0,92). Optimal kesim noktaları keratokonus için 3,55 mm 3 , subklinik keratokonus için ise 3,65 mm 3 idi. Bu değerler, kera...

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Corneal thickness measurements in normal and keratoconic eyes: Pentacam comprehensive eye scanner versus noncontact specular microscopy and ultrasound pachymetry

Cited by 165 publications

References 23 publications

Ability of corneal biomechanical metrics and anterior segment data in the differentiation of keratoconus and healthy corneas

Ability of corneal biomechanical metrics and anterior segment data in the differentiation of keratoconus and healthy corneas

Corneal biomechanical evaluation in healthy thin corneas compared with matched keratoconus cases

Keratokonus ve Subklinik Keratokonusun Tespit Edilmesi için Pentacamla Korneal Hacim Ölçümleri

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