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초록
Purpose:
To investigate the cause of failure in the correction of childhood myopia using orthokeratologic (Ortho-K) lenses.
Methods:
The failure group was 29 patients who stopped wearing the lenses for various reasons, while the success group was 29 patients who bought lenses more than twiceand wore them for two years and more. Statistical analyses were performed to identify significant differences between the groups.
Results:
Among the failure group, failure to continuously wear the Ortho-K lenses was attributed to undercorrection (19 patients), corneal erosion (2 patients), and sleep disorders (1 patient). Initial spherical diopter and initial spherical equivalent diopter showed statistical diffence between the success group and failure group. Of these two factors, as the initial spherical equivalent diopter increased, the chance of failure to use Ortho-K lens increased. According to a logistic multiple regression analysis, the odds of failure of using Ortho-K lens increased by 1.59 when the initial spherical diopter increased by 1. If the absolute value of the initial spherical diopter was over 6.24, the chance of failure increased by 80%.
Conclusions:
The failure of continuously wearing Ortho-K lenses due to undercorrection was found to be the major cause of failure in the correction of childhood myopia. The initial spherical diopter and initial spherical equivalent diopter were significant factors influencing the undercorrection. From these results, we predict that the odds of failure of continuously wearing Ortho-K lenses increases along with increases in the initial spherical diopter. In conclusion, clinicians should be warned concerning the odds of failure due to low initial spherical diopter.
References
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Figure 1.
Causes of failure on corneal topography within 3 months. (A), (B), and (C) show an example of corneal topologies for the patients of failure group with decentration, central island, and incomplete corneal reshaping, respectively. The left column in the figure is for before wearing Ortho-K lens, and the right one is for after wearing lens. Ortho-K = orthokeratologic.
Table 1.
Demographic data of success and failure groups
| Success group | Failure group† | p-value | |
|---|---|---|---|
| Sex (M:F) | 11:18 | 7:15 | 0.685‡ |
| Age (years) | 9.72 ± 2.43 | 9.00 ± 2.27 | 0.416§ |
| log VA* | -0.92 ± 0.22 | -0.99 ± 0.40 | 0.433§ |
Table 2.
Comparison between success group and failure group* in wearing Ortho-K lenses continuously
| Success group | Failure group* | p-value | |
|---|---|---|---|
| Initial spherical diopter | -2.65 ± 0.99 | -3.48 ± 1.78 | <0.001 |
| Initial cylindrical diopter | -0.46 ± 0.31 | -0.65 ± 0.37 | 0.298 |
| Initial spherical equivalent diopter | -2.88 ± 0.99 | -3.80 ± 1.86 | <0.001 |
| Pachymetry (µm) | 532.76 ± 27.72 | 532.05 ± 40.29 | 0.127 |
| K min (diopter) | 43.11 ± 1.18 | 42.65 ± 1.10 | 0.994 |
| K max (diopter) | 44.13 ± 1.25 | 44.02 ± 1.14 | 0.704 |
| Increment of spherical diopter | 2.12 ± 0.83 | 0.82 ± 1.88 | 0.006 |
| Increment of spherical equivalent diopter | 2.11 ± 0.83 | 0.67 ± 0.45 | 0.005 |
| Increment of log VA | 0.90 ± 0.21 | 0.63 ± 0.42 | <0.001 |
Values are presented as mean ± SD; All component of success and failure group was compared to each other before using orthokeratologic lens; Increment of spherical diopter, spherical equivalent diopter and logarithmic visual acuity is difference between initial values and final measured values.
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