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Abstract
Purpose
To evaluate the accuracy of Pentacam® built-in 5 intraocular pressure (IOP) correction programs used to measure the IOP of patients who received corneal refractive surgery.
Methods
IOP of 124 eyes from 62 patients who underwent epipolis laser in situ keratomileusis was measured with Goldmann applanation tonometry (GAT) at 6 months pre- and post-operatively. The collected data was input into Pentacam®, calculated by 5 correction programs, Ehlers, Shah, Dresden, Orssengo / Pye, Kohlhaas, and compared.
Results
The GAT-based pre- and post-operative IOP was 15.75 ± 2.24 mm Hg, and 10.72 ± 2.31 mm Hg, respectively, revealing the post-operative IOP to be significantly lower than the pre-operative IOP (p < 0.001). Among the 5 correction programs within Pentacam®, Ehlers program showed little difference between pre- and post-operative IOP values (p = 0.228) and the post-operative correction value showed no significant difference with the pre-operative GAT value (p = 0.413).
References
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Figure 2.
Comparison between preoperative and postoperative IOP and IOP c. IOP was checked by Goldmann and IOP c was calculated by formula in pentacam. IOP c showed significant difference in Shah, Dresden, Orssengo / Pye, Kohlhaas formula (p = 0.015, p = 0.001, p = 0.001, p < 0.001, respectively), except in Ehlers formula (p = 0.228). IOP = intraocular pressure; IOP c = corrected intraocular pressure.
Figure 3.
Comparison between preoperative GAT with post-operative IOP c after epi-LASIK by the 5 correction methods. There is significant difference with IOP c (by Shah, Dresden, Orssengo / Pye, Kohlhaas), but no significant difference with IOP c by Ehlers. Postoperative IOP c by Ehlers is most consistent with preoperative GAT. GAT = Goldmann applanation tonometric intraocular pressure; IOP c = corrected intraocular pressure; Epi-LASIK = epipolis laser in situ keratomileusis. * p < 0.05.
Figure 4.
Difference between corrected preoperative IOP and corrected postoperative IOP, plotted against the mean of the two measurements. The mean difference obtained by Ehlers was 0.13 mm Hg and the 95% limit of agreement was ±0.97 mm Hg, among these 5 groups Ehlers is the smallest. Mean difference IOP = corrected preoperative IOP – corrected postoperative IOP.
Table 1.
Subjects' demographic and clinical data
| Preoperative | 6 mons Postoperative | Difference* | |
|---|---|---|---|
| Number (eyes) | 62 (124) | ||
| Age (yrs) | 29.6 ± 2.4 | ||
| Sex (M:F) | 32:30 | ||
| Mean ablation depth (μ m) | 65.3 ± 12.7 | ||
| SE (D) | –3.74 ± 1.59 | –0.89 ± 0.52 | |
| Goldmann-IOP (mm Hg) | 15.75 ± 2.24 | 10.72 ± 2.31 | 5.37 ± 1.21 |
| CCT (μ m) | 557 ± 33 | 470 ± 32 | 72 ± 24 |
| Corneal curvature (mm) | 7.74 ± 0.24 | 8.51 ± 0.35 | –1.56 ± 0.35 |
Table 2.
Correlation of IOPc by 5 methods with CCT and K
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