AI Article Synopsis
- The study aimed to compare the calculated sagittal height of the anterior eye (OC-SAG) using corneal parameters with the actual measurements obtained through profilometry.
- Seventy right eyes of soft contact lens wearers were analyzed, measuring OC-SAG with various chord diameters and comparing these calculations with values from a profilometer, leading to significant differences noted especially as chord diameters increased.
- The results indicated that while calculations using different methods showed varying degrees of accuracy, the discrepancies between calculated and measured OC-SAG values were statistically significant, particularly for larger chord diameters, suggesting the importance of accurate measurement in custom lens fitting.
Article Abstract
Purpose: To compare the sagittal height of the anterior eye (OC-SAG) calculated using corneal parameters with the OC-SAG measured by profilometry.
Method: Seventy right eyes of soft contact lens wearers measured with the ESP (Eaglet Eye, The Netherlands) after lens removal were retrospectively analyzed for this study. The OC-SAG of the eyes was calculated using mean k-values, eccentricity and the inner (corneal) radius obtained with the ESP for an 11-mm cord diameter. It was then extrapolated to chord diameters of 14, 14.5 and 15 mm. These values were compared with OC-SAG values obtained with the ESP for the same chord diameters. Additionally, the OC-SAG was calculated through the formula used by a lab that manufactures custom soft lenses (mark'ennovy, Madrid, Spain) and compared again with the values obtained using the ESP.
Results: Differences between calculated OC-SAG obviating the shape factor were 121 ± 44, 155 ± 105, 172 ± 117 and 189 ± 129 µm for chord diameters of 11, 14, 14.5 and 15 mm, respectively (p < 0.001). When the shape factor was included in the calculation, differences were 28 ± 48, 62 ± 102, 79 ± 113 and 96 ± 123 µm (p < 0.001). When the inner best fit sphere was used to estimate OC-SAG, differences were 34 ± 11, 0 ± 72, 17 ± 86 and 34 ± 99, respectively, with no significant differences for the 14 and 14.5 mm-chord diameters (p = 0.99 and 0.11, respectively). Correlation coefficients between OC-SAG calculated and measured OC-SAG ranged from 0.53 to 0.90 depending on the chord diameter used. When the mark'ennovy formula was used to calculate the OC-SAG as the lens diameter proposed by the formula, the difference was -47 ± 147 µm (p < 0.01).
Conclusions: Differences between the OC-SAG calculated using corneal parameters and that measured with a profilometer are statistically and clinically significant, especially for large chord diameters. The impact of this on contact lens fitting should be addressed in future studies.
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Source |
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| http://dx.doi.org/10.1016/j.clae.2022.101747 | DOI Listing |
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