A New Method for Grading the Severity of Keratoconus

McMahon, Timothy T.; Szczotka-Flynn, Loretta; Barr, Joseph T.; Anderson, Robert J.; Slaughter, Mary Ellen; Lass, Jonathan H.; Iyengar, Sudha K.

doi:10.1097/01.ico.0000226359.26678.d1

Cited by 177 publications

(127 citation statements)

References 51 publications

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“…Diagnosis of keratoconus was made by clinical (corneal stromal thinning, Vogt's striae, Fleischer ring, scissoring of the red reflex or oil droplet sign identified by retinoscopy) and topographic evaluation (increased area of corneal power surrounded by concentric areas of decreasing power, inferior-superior power asymmetry, and skewing of the steepest radial axis above and below the horizontal meridian (22)(23)(24) .…”

Section: Methodsmentioning

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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Section: Methodsmentioning

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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“…Despite the reduced rate of progression of KC with increasing age, KC can progress in older patients, resulting in reduced visual acuity and quality of life. 1,[6][7][8] Whether iatrogenic CXL in older adults with naturally cross-linked corneas has the same positive effect as in younger adults is unknown. A recent study on the safety of CXL found that age Z35 years was a major risk factor for adverse events after CXL.…”

Section: Introductionmentioning

confidence: 99%

Effects and adverse events after CXL for keratoconus are independent of age: a 1-year follow-up study

Baenninger

Bachmann

Wienecke

et al. 2014

Eye

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Purpose To compare the effect, failure rate and the risks of corneal cross-linking (CXL) in keratoconus patients aged Z35 years to patients o35 years. Methods In 141 eyes of 116 keratoconus patients we compared the changes in best phoropter-corrected visual acuity (BCVA) and maximum keratometry values (K max ) before and 12 months after CLX in patients aged Z35 years (n ¼ 34, 38 eyes) to the cohort of patients below 35 years of age. Results Overall, CXL significantly improved BCVA from 0.487 logMAR (95% confidence interval (CI) 0.426-0.548) by À 0.197 logMAR (95% CI À 0.243 to À 0.150; Po0.001) and reduced K max from 48.96 diopter (Dpt) by À 1.33 Dpt (95% CI À 1.85 to À 0.81: Po0.001). Age Z35 years had no effect on the changes of BCVA ( À 0.02 (95% CI À 0.13 to 0.09); P ¼ 0.757) or K max (0.58 (95%CI À 0.51 to 1.68); P ¼ 0.294) as compared with younger patients. In 54 patients (55 eyes, 38.5%) aged o35 years and in 18 patients (18 eyes, 47.4%) aged Z35 years, BCVA increased by Z2 Snellen lines. Failure (increase in K max Z1 Dpt) was observed in 17 eyes (16.5%) of patients aged o35 years and in 3 eyes (7.9%) of patients aged Z35 years during the 12-month follow-up period. Adverse outcomes (loss of Z2 Snellen lines) occurred in 4 (3.9%) eyes of patients aged o35 years and 1 (2.6%) eye of a patient aged Z35 years. Conclusion Effects and adverse events of CXL treatment do not seem to differ between subjects younger or older than 35 years.

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“…28 Habitual correction for 3 patients (5 eyes) consisted of a thick soft CL design for keratoconus, 2 patients (3 eyes) were wearing GP corneo-scleral CL and the other 13 patients (25 eyes) were wearing aspheric GP CL for keratoconus. Three patients AU7 discontinued the study before 1 month after fitting of the Clearkone lens, one (1 eye) for presenting with diffuse corneal staining after 1 day of wear, 2 patients (4 eyes) discontinued after reporting significant discomfort after 4 to 5 hours of wear, and 2 patients discontinued because of difficulty with insertion of the lenses.…”

Section: Resultsmentioning

confidence: 99%

Clinical Performance of a New Hybrid Contact Lens for Keratoconus

Carracedo

González-Meijóme

Lopes-Ferreira

et al. 2014

Eye &Amp; Contact Lens: Science &Amp; Clinical Practice

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A New Method for Grading the Severity of Keratoconus

Abstract: A simple and reliable grading system for keratoconus was developed that can be largely automated. Such a grading scheme could be useful in genetic studies for a complex trait such as keratoconus requiring a quantitative measure of disease presence and severity.

Cited by 177 publications

References 51 publications

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

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

Effects and adverse events after CXL for keratoconus are independent of age: a 1-year follow-up study

Clinical Performance of a New Hybrid Contact Lens for Keratoconus

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