**6. Conclusions**

**5. IOL power calculation in post-myopic excimer laser eyes using** 

deviation from the target refraction is not large (**Figure 8**).

cially meaningful for eyes whose prior data unavailable.

It is well known that correct IOL power calculation in patients undergoing cataract surgery depends mainly on the accurate measurement of corneal power, axial length, corneal keratometry, and the effective lens position after surgery [44, 45]. Due to index of refraction error, instrument error, and IOL formula error, precise prediction of IOL power is always a big challenge for cataract surgery in patients with previous corneal refractive surgery (PRK, LASIK, RK) [46–51]. For post corneal refractive surgery cataract patients, both, patient expectations of spectacle independence and reduction in the accuracy of conventional IOL power calculation formulas due to previous corneal surgery should be considered. To deal with these issues, many innovative post-corneal refractive surgery IOL power calculation formulas have been developed [52–58]. Compared to traditional keratometry, RTVue spectral-domain AS-OCT can measure anterior and posterior corneal curvature and then calculate the net corneal power, which in conjunction with IOLMaster biometry data (AL, ACD) provides the IOL power [59]. Previous studies have demonstrated that Fourier-domain AS-OCT can provide highly repeatable corneal power measurement and spectral-domain OCT-based IOL formulas have also provided promising results in post-refractive surgery IOL calculation in eyes undergoing cataract surgery; this is especially meaningful for patients for whom prior data are not available [59–61]. To avoid significant IOL power fluctuation between different formulas, surgeons can also use ASCRS online post-refractive IOL calculator (link: http://iolcalc. ascrs.org/) to get the average IOL power value to make sure the real postoperative refraction

Anterior segment SD-OCT can noncontactly provide true net corneal power, which is essential for IOL power calculation after excimer laser corneal surgery. The SD-OCT-based IOL formulas enable to provide promising results in post-refractive surgery IOL calculation, espe-

**Figure 8.** Average IOL power information for all available formulas using ASCRS online post-refractive IOL calculator.

**SD-OCT**

184 OCT - Applications in Ophthalmology

**5.1. Summary**

In conclusion, OCT, as a noninvasive and high-resolution imaging technology, can provide the ophthalmologist with clinically useful findings not only about the retina, but also for the cornea, lens, and anterior chamber. Anterior segment high-speed SD-OCT system offers efficient information about lens capsule evaluation, clear corneal incision investigation, capsular block syndrome management, and post-refractive surgery IOL power calculation. In the future, anterior segment SD-OCT may be a useful tool for detecting and monitoring more ocular disease progression and treatment response in clinic.
