Comparison of anterior section parameters using anterior segment optical coherence tomography and ultrasound biomicroscopy in myopic patients after ICL implantation

AIM：To compare the agreement of anterior chamber depth（ACD）and central vault measurements obtained by anterior segment optical coherence tomography（AS-OCT）and ultrasound biomicroscopy（UBM）of post surgical high myopic eyes with posterior chamber phakic intraocular lens（Visian ICL;STAAR Surgical）implantation.·METHODS：Fifty-two phakic eyes of 28 high myopic patients who underwent implantable Collamer lens（ICL）surgery for the correction of high myopia were studied.The postoperative ACD,the distance between the corneal endothelium and the anterior surface of ICL（cornea-ICL）and the central vault were measured with the AS-OCT system and the UBM system.Intraclass correlation coefficient（ICC）and the Bland-Altman plot were used to evaluate the repeatability and agreement of two devices.·R ESULTS：The mean ACD,cornea-ICL and central vault in the 52 phakic eyes after ICL surgery was 3.19±0.28 mm,2.47±0.28 mm,0.50±0.19 mm by AS-OCT and3.13±0.25 mm,2.49±0.25 mm,0.44±0.19 mm by UBM,respectively.Pairwise comparison of ACD and central vault measurements showed significant differences between AS-OCT and UBM（〈0.05）.However,no statistically significant difference was found between these imaging techniques in cornea-ICL（〉0.05）.The Pearson correlation coefficient（）between AS-OCT and UBM measurements for ACD,cornea-ICL and vault was0.88,0.80 and 0.89,respectively（〈0.001）.The ICC was0.89-0.94 for the measurements of AS-OCT and UBM.Bland-Altman analysis showed the 95%limits of agreement of ACD,cornea-ICL,central vault measurements between these two devices were-0.20 to 0.32 mm,-0.36to 0.32 mm and-0.12 to 0.24 mm,respectively.58·CONCLUSION：Central ACD and vault measurements using AS-OCT demonstrated a slight significantly higher value than using UBM in phakic eyes after ICL surgery.These two devices should not be used interchangeably for measurements of central ACD and vault in patients after phakic intraocular lens implantation.

Agreement of angle closure assessments between gonioscopy, anterior segment optical coherence tomography and spectral domain optical coherence tomography

AIM: To determine angle closure agreements between gonioscopy and anterior segment optical coherence tomography(AS-OCT), as well as gonioscopy and spectral domain OCT(SD-OCT). A secondary objective was to quantify inter-observer agreements of AS-OCT and SD-OCT assessments.METHODS: Seventeen consecutive subjects(33 eyes)were recruited from the study hospital’s Glaucoma clinic.Gonioscopy was performed by a glaucomatologist masked to OCT results. OCT images were read independently by 2 other glaucomatologists masked to gonioscopy findings as well as each other’s analyses of OCT images.RESULTS: Totally 84.8% and 45.5% of scleral spurs were visualized in AS-OCT and SD-OCT images respectively(P 【0.01). The agreement for angle closure between AS-OCT and gonioscopy was fair at k =0.31(95% confidence interval, CI: 0.03-0.59) and k =0.35(95%CI: 0.07-0.63) for reader 1 and 2 respectively. The agreement for angle closure between SD-OCT and gonioscopy was fair at k =0.21(95% CI: 0.07-0.49) and slight at k =0.17(95% CI: 0.08-0.42) for reader 1 and 2 respectively. The inter-reader agreement for angle closure in AS-OCT images was moderate at 0.51(95% CI: 0.13-0.88). The inter-reader agreement for angle closure in SD-OCT images was slight at 0.18(95% CI: 0.08-0.45).CONCLUSION: Significant proportion of scleral spurs were not visualised with SD-OCT imaging resulting in weaker inter-reader agreements. Identifying other angle landmarks in SD-OCT images will allow more consistent angle closure assessments. Gonioscopy and OCT imaging do not always agree in angle closure assessments but have their own advantages, and should be used together and not exclusively.