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Agreement between clinical history method, Orbscan IIz, and Pentacam in estimating corneal power after myopic excimer laser surgery.

Lekhanont K, Nonpassopon M, Wannarosapark K, Chuckpaiwong V - PLoS ONE (2015)

Bottom Line: The mean Orbscan IIz 3.0-mm total optical power was the lowest keratometric reading compared to the other 5 values.In conclusion, the keratometric values extracted from these 3 methods were disparate, either because of a statistically significant difference in the mean values or moderate agreement between them.Therefore, they are not considered equivalent and cannot be used interchangeably.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.

ABSTRACT
The purpose of this study was to investigate the agreement between the clinical history method (CHM), Orbscan IIz, and Pentacam in estimating corneal power after myopic excimer laser surgery. Fifty five patients who had myopic LASIK/PRK were recruited into this study. One eye of each patient was randomly selected by a computer-generated process. At 6 months after surgery, postoperative corneal power was calculated from the CHM, Orbscan IIz total optical power at the 3.0 and 4.0 mm zones, and Pentacam equivalent keratometric readings (EKRs) at 3.0, 4.0, and 4.5 mm. Statistical analyses included multilevel models, Pearson's correlation test, and Bland-Altman plots. The Orbscan IIz 3.0-mm and 4.0 mm total optical power, and Pentacam 3.0-mm, 4.0-mm, and 4.5-mm EKR values had strong linear positive correlations with the CHM values (r = 0.90-0.94, P = <0.001, for all comparisons, Pearson's correlation). However, only Pentacam 3.0-mm EKR was not statistically different from CHM (P = 0.17, multilevel models). The mean 3.0- and 4.0-mm total optical powers of the Orbscan IIz were significantly flatter than the values derived from CHM, while the average EKRs of the Pentacam at 4.0 and 4.5 mm were significantly steeper. The mean Orbscan IIz 3.0-mm total optical power was the lowest keratometric reading compared to the other 5 values. Large 95% LoA was observed between each of these values, particularly EKRs, and those obtained with the CHM. The width of the 95% LoA was narrowest for Orbscan IIz 3.0-mm total optical power. In conclusion, the keratometric values extracted from these 3 methods were disparate, either because of a statistically significant difference in the mean values or moderate agreement between them. Therefore, they are not considered equivalent and cannot be used interchangeably.

No MeSH data available.


Bland-Altman plots showing differences in values of the estimated postoperative corneal power for comparisons between pairs of instruments.The 95% limits of agreement between the Orbscan IIz and CHM were wide. Agreement was even poorer when comparing the EKR at 3.0, 4.0, and 4.5 mm from Pentacam and CHM. CHM = clinical history method, TOP = total optical power from Orbscan IIz, EKR = equivalent keratometric readings from Pentacam.
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pone.0123729.g001: Bland-Altman plots showing differences in values of the estimated postoperative corneal power for comparisons between pairs of instruments.The 95% limits of agreement between the Orbscan IIz and CHM were wide. Agreement was even poorer when comparing the EKR at 3.0, 4.0, and 4.5 mm from Pentacam and CHM. CHM = clinical history method, TOP = total optical power from Orbscan IIz, EKR = equivalent keratometric readings from Pentacam.

Mentions: Table 1 shows the postoperative corneal power measured from the 3 different methods, including their deviation from CHM. There were statistically significant differences among the estimated postoperative keratometric values derived from the 2 instruments and CHM (P = <0.001, multilevel models), except for the 3.0-mm EKR (P = 0.17). The corneal power values from both Orbscan IIz 3.0- and 4.0-mm total optical power maps tended to be flatter than those from CHM. Conversely, the average Pentacam EKRs at 4.0 and 4.5 mm diameters appeared to be steeper. The mean Orbscan IIz 3.0-mm total optical power was the lowest keratometric reading compared to the other 5 values. Strong linear positive correlations were found between each of these values obtained with Orbscan IIz or Pentacam, and historical-based values (r = 0.90–0.94, P = <0.001, for all comparisons, Pearson’s correlation). The Orbscan IIz 3.0-mm total optical power had the closest correlation with clinical history method (r = 0.94). The 95% LoA between the Orbscan IIz and CHM were wide (-1.05 to +2.53 D for 3.0-mm total optical power and -1.37 to +2.43 D for 4.0-mm total optical power). Agreement was even poorer when comparing the EKR at 3.0, 4.0, and 4.5 mm from Pentacam and CHM (-2.48 to +2.12 D, -2.57 to +1.65 D, and -2.72 to +1.47 D, respectively) (Fig 1).


Agreement between clinical history method, Orbscan IIz, and Pentacam in estimating corneal power after myopic excimer laser surgery.

Lekhanont K, Nonpassopon M, Wannarosapark K, Chuckpaiwong V - PLoS ONE (2015)

Bland-Altman plots showing differences in values of the estimated postoperative corneal power for comparisons between pairs of instruments.The 95% limits of agreement between the Orbscan IIz and CHM were wide. Agreement was even poorer when comparing the EKR at 3.0, 4.0, and 4.5 mm from Pentacam and CHM. CHM = clinical history method, TOP = total optical power from Orbscan IIz, EKR = equivalent keratometric readings from Pentacam.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390196&req=5

pone.0123729.g001: Bland-Altman plots showing differences in values of the estimated postoperative corneal power for comparisons between pairs of instruments.The 95% limits of agreement between the Orbscan IIz and CHM were wide. Agreement was even poorer when comparing the EKR at 3.0, 4.0, and 4.5 mm from Pentacam and CHM. CHM = clinical history method, TOP = total optical power from Orbscan IIz, EKR = equivalent keratometric readings from Pentacam.
Mentions: Table 1 shows the postoperative corneal power measured from the 3 different methods, including their deviation from CHM. There were statistically significant differences among the estimated postoperative keratometric values derived from the 2 instruments and CHM (P = <0.001, multilevel models), except for the 3.0-mm EKR (P = 0.17). The corneal power values from both Orbscan IIz 3.0- and 4.0-mm total optical power maps tended to be flatter than those from CHM. Conversely, the average Pentacam EKRs at 4.0 and 4.5 mm diameters appeared to be steeper. The mean Orbscan IIz 3.0-mm total optical power was the lowest keratometric reading compared to the other 5 values. Strong linear positive correlations were found between each of these values obtained with Orbscan IIz or Pentacam, and historical-based values (r = 0.90–0.94, P = <0.001, for all comparisons, Pearson’s correlation). The Orbscan IIz 3.0-mm total optical power had the closest correlation with clinical history method (r = 0.94). The 95% LoA between the Orbscan IIz and CHM were wide (-1.05 to +2.53 D for 3.0-mm total optical power and -1.37 to +2.43 D for 4.0-mm total optical power). Agreement was even poorer when comparing the EKR at 3.0, 4.0, and 4.5 mm from Pentacam and CHM (-2.48 to +2.12 D, -2.57 to +1.65 D, and -2.72 to +1.47 D, respectively) (Fig 1).

Bottom Line: The mean Orbscan IIz 3.0-mm total optical power was the lowest keratometric reading compared to the other 5 values.In conclusion, the keratometric values extracted from these 3 methods were disparate, either because of a statistically significant difference in the mean values or moderate agreement between them.Therefore, they are not considered equivalent and cannot be used interchangeably.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.

ABSTRACT
The purpose of this study was to investigate the agreement between the clinical history method (CHM), Orbscan IIz, and Pentacam in estimating corneal power after myopic excimer laser surgery. Fifty five patients who had myopic LASIK/PRK were recruited into this study. One eye of each patient was randomly selected by a computer-generated process. At 6 months after surgery, postoperative corneal power was calculated from the CHM, Orbscan IIz total optical power at the 3.0 and 4.0 mm zones, and Pentacam equivalent keratometric readings (EKRs) at 3.0, 4.0, and 4.5 mm. Statistical analyses included multilevel models, Pearson's correlation test, and Bland-Altman plots. The Orbscan IIz 3.0-mm and 4.0 mm total optical power, and Pentacam 3.0-mm, 4.0-mm, and 4.5-mm EKR values had strong linear positive correlations with the CHM values (r = 0.90-0.94, P = <0.001, for all comparisons, Pearson's correlation). However, only Pentacam 3.0-mm EKR was not statistically different from CHM (P = 0.17, multilevel models). The mean 3.0- and 4.0-mm total optical powers of the Orbscan IIz were significantly flatter than the values derived from CHM, while the average EKRs of the Pentacam at 4.0 and 4.5 mm were significantly steeper. The mean Orbscan IIz 3.0-mm total optical power was the lowest keratometric reading compared to the other 5 values. Large 95% LoA was observed between each of these values, particularly EKRs, and those obtained with the CHM. The width of the 95% LoA was narrowest for Orbscan IIz 3.0-mm total optical power. In conclusion, the keratometric values extracted from these 3 methods were disparate, either because of a statistically significant difference in the mean values or moderate agreement between them. Therefore, they are not considered equivalent and cannot be used interchangeably.

No MeSH data available.