Abstract:

Objective

To investigate the difference of surgical target angles measured by different methods and the selection of surgical procedure in acute acquired comitant esotropia（AACE）.

Methods

Thirty-nine consecutive AACE patients（56 eyes）underwent surgery at the Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine from September 2022 to September 2023 were collected.Among of them，there were 32 males（46 eyes）and 7 famles（10 eyes）with an averange of（18.7±11.2）years-old（ranging from 5 to 50 years-old）.Four methods were used to measure the preoperative angle of deviation，including the prism and alternative cover test（PACT），the maddox rod and prism test（MRPT），the baseout recovery point（BORP）and the prism adaptation test（PAT）.The average value of the maximum angles at distance and near was used as the surgical target angle.The surgical method was the unilateral or bilateral medial rectus recession（MRc）procedure or the recession and resection（RR）procedure.The difference in angles measured by different methods and the effect of different surgical procedures were analyzed.A successful surgical alignment was defined as the distance and near angle within±8^△with no diplopia.The equivalent spherical lens and deviation were performed with normality test and described by±s or M（Q1，Q3），and compared by t-test or Wilcoxon rank sum test.The comparison of preoperative four methods for measuring oblique angle was conducted using ANOVA.When the difference was statistically significant，further pairwise comparisons were made.The comparison of preoperative oblique angle increment between typeⅡand typeⅢAACE patients was conducted using a grouped t-test.The comparison between the actual surgical increments of MRC and RR procedures was conducted using a grouped t-test.The comparison of fusion function before and after surgery was conducted using paired t-test or Wilcoxon rank sum test.Count data was expressed in frequency and percentage，and comparison between groups was performed using the chi square test.

Results

The mean preoperative angles measured by PACT at distance and near were（33.5±12.4）^△and（34.6±15.6）^△，respectively.The augmentation of the angle at distance measured by MRPT was（6.6±4.6）^△，and the difference was statistically significant（t＝2.11，P＜0.05）.The augmentation of the angle at near measured by MRPT was（5.4±4.3）^△with no statistically significant difference（t＝1.38，P＞0.05）.The angle measured by BORPwas larger than that measured by PACT the augmentation at distance and at near were（12.5±7.4）^△，（16.9±11.6）^△，respectively.There were significant differences between them（t＝4.00，4.31；P＜0.05）.The angle measured by PAT was larger than that measured by PACT the augmentation at distance and at near were（11.8±7.8）^△，（16.5±11.1）^△，respectively.There were significant differences between them（t＝3.78，4.23；P＜0.05）.There was no significant difference between angles measured by BORP and PAT at distance or at near（t＝0.22，0.08；P＞0.05）.The average time of PAT was（11.1±4.1）hours.All patients achieved successful surgical alignment after one surgery.The actual augmentation of the surgical amount of MRc and RR procedures based on the PACTwas（3.4±1.5）mm and（2.8±2.3）mm，respectively，with no statistical significance（t＝-0.91，P＞0.05）.The actual augmentation of the surgical amount of MRc and RR procedures based on the BORP or PAT was（0.8±1.4）mm and（0.04±0.4）mm，respectively，and the difference was statistically significant（t＝-2.87，P＜0.05）.

Conclusions

The BORP and PAT may have equivalent effect to uncover the latent angle of AACE fully，and can effectively treat AACE as the surgical target angle.The RR procedure presented superiority with less surgical augmentation than the MRc procedure in AACE surgery.

Key words: Acute acquired comitant esotropia, Base-out recovery point, Prism adaptation test, Strabismus surgical procedures