Comparison of the morphological and biomechanical characteristics of keratoconus, forme fruste keratoconus, and normal corneas

ABSTRACT Purpose To compare corneal elevation values in normal eyes, forme fruste keratoconus (FFKC) and different stages of keratoconus using Scheimpflug imaging. Materials and methods This prospective, comparative study included 267 eyes (107 normal eyes, 21 FFKC and 139 keratoconus). Keratoconic eyes were divided into four groups according to keratometry values. Maximum posterior elevation (PE) above the (best fit sphere (BFS) at the central 5 mm were measured using the Pentacam (Oculus Optikgeräte GmbH). Receiver operating characteristic curves were used to determine the test's overall predictive accuracy and to identify optimal cutoff points to discriminate between the groups. Results PE had the smallest values in normal eyes and increased in FFKC and each progressive stage of keratoconus. Mean PE was 9.98 ± 5.33 µm in normal eyes, 18.09 ± 9.23 µm in FFKC and 24.97 µm ± 15.89, 37.82 ± 18.64, 46.82 ± 21.41 and 66.07 ± 39.09, in keratoconus stage I, II, III and IV respectively. Conclusion Posterior elevation values increased according to the severity of keratoconus disease. PE can be used as indicator of keratoconus progression. How to cite this article Henriquez MA, Izquierdo L Jr, Dañin D. Corneal Elevation Values in Normal Eyes, forme fruste Keratoconus and Keratoconus at Different Stages Measured by Scheimpflug Imaging. Int J Kerat Ect Cor Dis 2014;3(1):36-39.

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Late Onset of a Persistent, Deep Stromal Scarring After PRK and Corneal Cross-linking in a Patient With Forme Fruste Keratoconus

Journal of Refractive Surgery ◽

10.3928/1081597x-20140320-09 ◽

2014 ◽

Vol 30 (4) ◽

pp. 286-288 ◽

Cited By ~ 13

Author(s):

Jose L. Güell ◽

Paula Verdaguer ◽

Daniel Elies ◽

Oscar Gris ◽

Felicidad Manero

Keyword(s):

Late Onset ◽

Cross Linking ◽

Forme Fruste Keratoconus

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Evaluation of Biomechanically Corrected Intraocular Pressure Measurements in Keratoconus and Forme Fruste Keratoconus

Ophthalmic Research ◽

10.1159/000506839 ◽

2020 ◽

Vol 63 (6) ◽

pp. 541-549

Author(s):

Tomoya Nishida ◽

Takashi Kojima ◽

Takahiro Kataoka ◽

Naoki Isogai ◽

Yoko Yoshida ◽

...

Keyword(s):

Intraocular Pressure ◽

Biomechanical Properties ◽

Control Group ◽

Pressure Measurements ◽

Altman Plot ◽

Significant Difference ◽

The Difference ◽

The Right ◽

Corneal Biomechanical Properties ◽

Forme Fruste Keratoconus

Introduction: Although biomechanically corrected intraocular pressure (bIOP) is available, the effectiveness of intraocular pressure (IOP) correction in keratoconus and forme fruste keratoconus (FFK) eyes has not been investigated. Objective: Evaluation of bIOP measurements in eyes with keratoconus and FFK. Methods: Forty-two eyes in 21 patients with keratoconus in one eye and FFK in the fellow eye were examined (KC/FFK group; mean age 24.62 ± 8.6 years; 16 males and 5 females). The control group consisted of 62 eyes in 31 unaffected subjects (mean age 26.26 ± 3.64 years; 15 males and 16 females). The bIOP was determined using a Scheimpflug-based tonometer (Corvis Scheimpflug Technology [Corvis ST®]) after measuring the IOP with a conventional non-contact tonometer (NIOP). The agreement between NIOP and bIOP values was examined using the Bland-Altman plot. The difference between NIOP and bIOP (bIOP correction amount) was compared between keratoconus and FFK eyes. Results: In the control group, there were no significant differences between right and left eyes in both NIOP and bIOP values (p = 0.975 and p = 0.224, respectively). In the KC/FFK group, NIOP values were significantly lower in the keratoconus eyes (9.93 ± 1.96 mm Hg) than in the FFK eyes (12.23 ± 3.03 mm Hg; p = 0.0003). There was no significant difference in bIOP values between the right and left eyes of the KC/FFK group (p = 0.168). The bIOP correction amount was significantly increased in keratoconus eyes (3.58 ± 2.12 mm Hg) compared to in FFK eyes (1.80 ± 3.32 mm Hg; p = 0.011). Conclusions: For eyes with keratoconus and FFK, the bIOP method is effective to adjust IOP measurements based on corneal biomechanical properties.

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The Role of Ocular Response Analyzer in Differentiation of Forme Fruste Keratoconus From Corneal Astigmatism

Eye & Contact Lens Science & Clinical Practice ◽

10.1097/icl.0000000000000541 ◽

2019 ◽

Vol 45 (2) ◽

pp. 83-87 ◽

Cited By ~ 2

Author(s):

Ahmet Kirgiz ◽

Sevil Karaman Erdur ◽

Kursat Atalay ◽

Ceren Gurez

Keyword(s):

Corneal Astigmatism ◽

Ocular Response Analyzer ◽

Forme Fruste Keratoconus

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Assessment of Visual Quality in Eyes with Forme Fruste Keratoconus and Mild and Moderate Keratoconus Based on Optical Quality Analysis System II Parameters

Journal of Ophthalmology ◽

10.1155/2020/7505016 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Zhonghao Ren ◽

Liyan Xu ◽

Qi Fan ◽

Kaili Yang ◽

Shengwei Ren ◽

...

Keyword(s):

Intraclass Correlation ◽

Visual Quality ◽

Quality Parameters ◽

Optical Quality ◽

Normal Group ◽

Quality Analysis ◽

Significant Difference ◽

Analysis System ◽

Forme Fruste Keratoconus

Purpose. The study aimed to evaluate the visual quality of forme fruste keratoconus (FFK) and mild and moderate keratoconus by using an optical quality analysis system II (OQAS-II) and to explore the correlation between optical quality parameters and the disease progression. Methods. Twenty-one normal eyes, twenty-one FFK eyes, twenty-one mild keratoconus eyes, and twenty-one moderate keratoconus eyes were included in this prospective study. The optical quality parameters, such as object scatter index (OSI), modulation transfer function cutoff (MTF cutoff), strehl ratio (SR), and OQAS-II values at contrasts of 100% (OV-100), 20% (OV-20), and 9% (OV-9), were measured by OQAS-II. The repeatability of these parameters was analyzed by intraclass correlation coefficient (ICC), repeatability coefficient (RC), and coefficient of variation (CVw). Correlations between optical quality parameters and mean central keratometry readings (Kmean) were evaluated. The sensitivity and specificity of the parameters were analyzed using the receiver operating characteristic (ROC). Results. All the optical quality parameters among four groups showed good repeatability (all ICC≥0.75). The MTF cutoff, SR, OV-100, OV-20, OV-9 in FFK, mild and moderate keratoconus eyes were significantly lower than those in the normal group (all P<0.05). The ROC analyses of the MTF cutoff, SR, OV-100, OV-20, and OV-9 showed significant area under the curve (AUC) in discriminating FFK form normal, mild keratoconus from FFK, and moderate keratoconus from mild keratoconus (all P<0.05). The OSI in mild and moderate keratoconus eyes were significantly higher than that in FFK and normal group (all P<0.05), while the OSI showed no significant difference between the FFK group and normal group (P>0.05). The ROC analyses of the OSI showed significant AUC in discriminating mild keratoconus from FFK and moderate keratoconus from mild keratoconus (all P<0.05). In addition, the MTF cutoff was closely correlated to Kmean in keratoconus eyes (r = −0.710, P<0.001). Conclusion. The repeatability of OQAS-II is good in measuring visual quality of normal as well as FFK, mild, and moderate keratoconus. The visual quality of the FFK, mild, and moderate keratoconus is worse than that in normal eyes. The OQAS-II has the potential value in screening FFK from normal eyes and might be a useful tool for evaluating the progression of keratoconus.

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