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Keratometric index obtained by Fourier-domain optical coherence tomography.

Hua Y, Stojanovic A, Utheim TP, Chen X, Ræder S, Huang J, Wang Q - PLoS ONE (2015)

Bottom Line: The ratio of anterior corneal curvature to posterior corneal curvature (Ratio) and keratometric index (N) were calculated within central 3 mm zone with the RTVue FD-OCT (RTVue, Optovue, Inc.) in 186 untreated eyes, 60 post-LASIK/PRK eyes, and 39 keratoconus eyes.The total corneal powers were calculated using different keratometric indices: Kcal based on the mean calculated keratometric index, K1.3315 calculated by the keratometric index of 1.3315, and K1.3375 calculated by the keratometric index of 1.3375.All the parameters were normally distributed.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China.

ABSTRACT

Purpose: To determine the keratometric indices calculated based on parameters obtained by Fourier-domain optical coherence tomography (FD-OCT).

Methods: The ratio of anterior corneal curvature to posterior corneal curvature (Ratio) and keratometric index (N) were calculated within central 3 mm zone with the RTVue FD-OCT (RTVue, Optovue, Inc.) in 186 untreated eyes, 60 post-LASIK/PRK eyes, and 39 keratoconus eyes. The total corneal powers were calculated using different keratometric indices: Kcal based on the mean calculated keratometric index, K1.3315 calculated by the keratometric index of 1.3315, and K1.3375 calculated by the keratometric index of 1.3375. In addition, the total corneal powers based on Gaussian optics formula (Kactual) were calculated.

Results: The means for Ratio in untreated controls, post-LASIK/PRK group and keratoconus group were 1.176 ± 0.022 (95% confidence interval (CI), 1.172-1.179), 1.314 ± 0.042 (95%CI, 1.303-1.325) and 1.229 ± 0.118 (95%CI, 1.191-1.267), respectively. And the mean calculated keratometric index in untreated controls, post-LASIK/PRK group and keratoconus group were 1.3299 ± 0.00085 (95%CI, 1.3272-1.3308), 1.3242 ± 0.00171 (95%CI, 1.3238-1.3246) and 1.3277 ± 0.0046 (95%CI, 1.3263-1.3292), respectively. All the parameters were normally distributed. The differences between Kcal and Kactual, K1.3315 and Kactual, and K1.3375 and Kactual were 0.00 ± 0.11 D, 0.21 ± 0.11 D and 0.99 ± 0.12 D, respectively, in untreated controls; -0.01 ± 0.20 D, 0.85 ± 0.18 D and 1.56 ± 0.16 D, respectively, in post-LASIK/PRK group; and 0.03 ± 0.67 D, 0.56 ± 0.70 D and 1.40 ± 0.76 D, respectively, in keratoconus group.

Conclusion: The calculated keratometric index is negatively related to the ratio of anterior corneal curvature to posterior corneal curvature in untreated, post-LASIK/PRK, and keratoconus eyes, respectively. Using the calculated keratometric index may improve the prediction accuracies of total corneal powers in untreated controls, but not in post-LASIK/PRK and keratoconus eyes.

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The multiple variables graphs of Rposterior values, Ratio and keratometric index (N) from the three group.A: The multiple variables graphs of Rposterior values from untreated controls, post-LASIK/PRK group and keratoconus group. B: the multiple variables graphs of Ratio values from untreated controls, post-LASIK/PRK group and keratoconus group. C: The multiple variables graphs of calculated keratometric index (N) from untreated controls, post-LASIK/PRK group and keratoconus group.
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pone.0122441.g002: The multiple variables graphs of Rposterior values, Ratio and keratometric index (N) from the three group.A: The multiple variables graphs of Rposterior values from untreated controls, post-LASIK/PRK group and keratoconus group. B: the multiple variables graphs of Ratio values from untreated controls, post-LASIK/PRK group and keratoconus group. C: The multiple variables graphs of calculated keratometric index (N) from untreated controls, post-LASIK/PRK group and keratoconus group.

Mentions: Fig 2 shows the multiple variable graphs of the mean Rposterior, Ratio and Keratometric index (N) in untreated controls, post-LASIK/PRK group and keratoconus group. In Fig 2A, the mean Rposterior from keratoconus group was significantly smaller than those from untreated and post-LASIK/PRK group (both P<0.05). And there was no statistical significance between the mean Rposterior values from untreated controls and post-LASIK/PRK group (P>0.05). In Fig 2B, both the mean Ratio from post-LASIK/PRK group and keratoconus group were larger than the mean Ratio from untreated controls (both P<0.05), and the mean Ratio from post-LASIK/PRK group was larger than that from keratoconus group (P<0.05). In Fig 2C, both the mean keratometric indices (Ncal) from post-LASIK/PRK group and keratoconus group were smaller than the mean Ratio from untreated controls (both P<0.05), and the mean N from post-LASIK/PRK group was smaller than that from keratoconus group (P<0.05).


Keratometric index obtained by Fourier-domain optical coherence tomography.

Hua Y, Stojanovic A, Utheim TP, Chen X, Ræder S, Huang J, Wang Q - PLoS ONE (2015)

The multiple variables graphs of Rposterior values, Ratio and keratometric index (N) from the three group.A: The multiple variables graphs of Rposterior values from untreated controls, post-LASIK/PRK group and keratoconus group. B: the multiple variables graphs of Ratio values from untreated controls, post-LASIK/PRK group and keratoconus group. C: The multiple variables graphs of calculated keratometric index (N) from untreated controls, post-LASIK/PRK group and keratoconus group.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401696&req=5

pone.0122441.g002: The multiple variables graphs of Rposterior values, Ratio and keratometric index (N) from the three group.A: The multiple variables graphs of Rposterior values from untreated controls, post-LASIK/PRK group and keratoconus group. B: the multiple variables graphs of Ratio values from untreated controls, post-LASIK/PRK group and keratoconus group. C: The multiple variables graphs of calculated keratometric index (N) from untreated controls, post-LASIK/PRK group and keratoconus group.
Mentions: Fig 2 shows the multiple variable graphs of the mean Rposterior, Ratio and Keratometric index (N) in untreated controls, post-LASIK/PRK group and keratoconus group. In Fig 2A, the mean Rposterior from keratoconus group was significantly smaller than those from untreated and post-LASIK/PRK group (both P<0.05). And there was no statistical significance between the mean Rposterior values from untreated controls and post-LASIK/PRK group (P>0.05). In Fig 2B, both the mean Ratio from post-LASIK/PRK group and keratoconus group were larger than the mean Ratio from untreated controls (both P<0.05), and the mean Ratio from post-LASIK/PRK group was larger than that from keratoconus group (P<0.05). In Fig 2C, both the mean keratometric indices (Ncal) from post-LASIK/PRK group and keratoconus group were smaller than the mean Ratio from untreated controls (both P<0.05), and the mean N from post-LASIK/PRK group was smaller than that from keratoconus group (P<0.05).

Bottom Line: The ratio of anterior corneal curvature to posterior corneal curvature (Ratio) and keratometric index (N) were calculated within central 3 mm zone with the RTVue FD-OCT (RTVue, Optovue, Inc.) in 186 untreated eyes, 60 post-LASIK/PRK eyes, and 39 keratoconus eyes.The total corneal powers were calculated using different keratometric indices: Kcal based on the mean calculated keratometric index, K1.3315 calculated by the keratometric index of 1.3315, and K1.3375 calculated by the keratometric index of 1.3375.All the parameters were normally distributed.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China.

ABSTRACT

Purpose: To determine the keratometric indices calculated based on parameters obtained by Fourier-domain optical coherence tomography (FD-OCT).

Methods: The ratio of anterior corneal curvature to posterior corneal curvature (Ratio) and keratometric index (N) were calculated within central 3 mm zone with the RTVue FD-OCT (RTVue, Optovue, Inc.) in 186 untreated eyes, 60 post-LASIK/PRK eyes, and 39 keratoconus eyes. The total corneal powers were calculated using different keratometric indices: Kcal based on the mean calculated keratometric index, K1.3315 calculated by the keratometric index of 1.3315, and K1.3375 calculated by the keratometric index of 1.3375. In addition, the total corneal powers based on Gaussian optics formula (Kactual) were calculated.

Results: The means for Ratio in untreated controls, post-LASIK/PRK group and keratoconus group were 1.176 ± 0.022 (95% confidence interval (CI), 1.172-1.179), 1.314 ± 0.042 (95%CI, 1.303-1.325) and 1.229 ± 0.118 (95%CI, 1.191-1.267), respectively. And the mean calculated keratometric index in untreated controls, post-LASIK/PRK group and keratoconus group were 1.3299 ± 0.00085 (95%CI, 1.3272-1.3308), 1.3242 ± 0.00171 (95%CI, 1.3238-1.3246) and 1.3277 ± 0.0046 (95%CI, 1.3263-1.3292), respectively. All the parameters were normally distributed. The differences between Kcal and Kactual, K1.3315 and Kactual, and K1.3375 and Kactual were 0.00 ± 0.11 D, 0.21 ± 0.11 D and 0.99 ± 0.12 D, respectively, in untreated controls; -0.01 ± 0.20 D, 0.85 ± 0.18 D and 1.56 ± 0.16 D, respectively, in post-LASIK/PRK group; and 0.03 ± 0.67 D, 0.56 ± 0.70 D and 1.40 ± 0.76 D, respectively, in keratoconus group.

Conclusion: The calculated keratometric index is negatively related to the ratio of anterior corneal curvature to posterior corneal curvature in untreated, post-LASIK/PRK, and keratoconus eyes, respectively. Using the calculated keratometric index may improve the prediction accuracies of total corneal powers in untreated controls, but not in post-LASIK/PRK and keratoconus eyes.

Show MeSH
Related in: MedlinePlus