Vaulting of Collagen Copolymer IOL as Indicator of Accurate White-to-White Measurement
Narrative Responses:
Purpose
To study whether the postoperative vault of an ICL can be used to assess the accuracy of white to white measurement with digital callipers.
Methods
In this prospective study ,15 eyes that underwent ICL implantation were subject to anterior segment OCT to assess the vaulting of the ICL with respect to the natural lens. This was compared with pre operative parameters including spherical refractive error, keratometry values, anterior chamber depth and white to white estimation.
Results
The white to white values negatively correlated with the anterior chamber depth(r=-0.48), weakly negatively correlated with the vault(r=-0.23), weakly correlated with the spherical error(r=0.21), all these being statistically significant (P=0.00). The AC depth and vaulting showed no correlation. The ratio of the vault of the ICL to the AC depth showed that normal ranged between 0.1 and 0.23. The ratio of the ICL vault to the wtw ranged between 0.027 and 0.071 for all normal vaults.
Conclusion
Incorporation of the wtw in a formula that assumes a fraction of acd to be the optimum vault would yield a ratio. When this ratio falls within the calculated range, it proves the wtw estimation to be accurate.