Abstract:  Objective To study the consistency between actual vault and the vault predictedby NK and KS formulas optimized by CASIA2. Design Diagnostic technique evaluation. Participants 68 cases (68 eyes) of ICL implantation in Hefei Aier Eye Hospital. Methods The Nomogram online formula was used to calculate 68 eyes' ICL models, and they were divided into three groups of 12.1 mm, 12.6 mm and 13.2 mm according to the recommended results of the online formula. Then CASIA2 was used to measure the actual vault. The difference, correlation and consistency were compared between the actual vault(V1d12.1, V1d12.6, V1d13.2) 1 day after operation, actual vault (V1m12.1, V1m12.6, V1m13.2) 1 month after operation in the above three types of groups and the vault predicted by NK and KS formulas before operation built-in CASIA2, and the coincidence rate was also compared among the ICL (V4c) model recommended by the online formula NK and KS, respectively. Main Outcome Measures Correlation and consistency between actual vault and formula predicted vault.  Results One day after surgery, the actual vault of all eyes (68 eyes) was (528.8±176.9) μm. One month after operation, it decreased to (476.8±161.2) μm. The vault predicted by NK formula was (656.2±204.5) μm and KS formula was (707.1±173.8) μm. The total coincidence rate between Nomogram online formula and NK formula was 55.88%, and the total coincidence rate with KS formula was 42.65%. The actual vault (V1d12.1, V1d12.6, V1d13.2) and the actual vault (V1m12.1, V1m12.6, V1m13.2) of the three ICL (V4c) groups at one day and one month after surgery were compared with the vault predicted by NK formula (VNK) and KS formula (VKS) respectively, except that there was no statistically significant difference between the vault of V1d12.1 group and VKS group (t=-2.056, P=0.079), the actual vault of other model groups were lower than those predicted by NK formula and KS formula (all P<0.05). The predicted vault of NK formula and KS formula was linear with V1d (Y=0.4728 * X+218.6, Y=0.5450 * X+143.4), it was also linear with V1m (Y=0.3985 * X+215.3, Y=0.4604 * X+151.2). The intra group correlation coefficients (ICC) between V1d and VNK, V1d and VKS formula was 0.541 and 0.536; the Cronbach coefficients was 0.702 and 0.700, respectively. The ICC between V1m and VNK, V1m and VKS formula was 0.492 and 0.495, the Cronbach coefficient was 0.659 and 0.662, respectively. Bland-Altman analysis showed that 95% LoA between V1d and vault predicted by NK formula and KS formula was (-486.5~231.7) μm, (-509.6~153.0) μm, respectively. 95% LoA between V1m and vault predicted by NK formula and KS formula was (-543.4~184.5) μm, (-560.6～99.86) μm, respectively. Conclusions The predicted vault of CASIA2 optimized NK and KS formulas is higher than the actual vault, and the accuracy of CASIA2 optimized NK and KS formulas for predicting small model group ICL (V4c) is slightly better. (Ophthalmol CHN, 2022, 31: 446-452)

Key words:  CASIA2, vault, intraocular lens implantation in Phakic eyes, NK formula, KS formula