ABSTRACT: BACKGROUND:Corneal densitometry, which is also known as corneal backscattering, is a surrogate measure of corneal clarity. The purpose of the study was to investigate the changes in corneal densitometry (CD) after implanting an implantable collamer lens (ICL-V4c). METHOD:Twenty-six high myopic patients (aged 29.3?±?6.6?years, 6 males and 20 females) who underwent ICL-V4c implantation were enrolled. Intraocular pressure (IOP), corneal topography, corneal densitometry, uncorrected distance visual acuity (UCDVA), manifest refraction, and best corrected distance visual acuity (BCDVA) were evaluated pre-operatively and at 1?day, 1?week, and 1, 3, 6, and 12?months post-operatively. Endothelial cell density (ECD) was measured pre-operatively and at 3, 6, and 12?months post-operatively. The efficacy index (mean post-operative UCDVA / mean pre-operative BCDVA) and the safety index (mean post-operative BCDVA / mean pre-operative BCDVA) were evaluated at 1?month, 3?months, 6?months and 12?months post-operatively. RESULTS:Over the annular diameters of 0-2?mm, the pre-operative densitometry values of the anterior layer, central layer, posterior layer, and total layer were 20.1?±?2.8, 11.8?±?1.1, 10.5?±?0.9 and 14.1?±?1.5, respectively. From pre-operatively to post-operative Month 12, the values changed insignificantly (P?=?0.177, P?=?0.153, P?=?0.543 and P?=?0.207, respectively). Over the annular diameters of 2-6?mm, the pre-operative mean densitometry values were 17.9?±?2.2, 10.5?±?0.9, and 12.6?±?1.2, respectively. From pre-operatively to post-operative Month 12, the values decreased to 16.5?±?2.1, 10.0?±?0.9, and 11.9?±?1.2, respectively, which were similar to the pre-operative values (all P?>?0.05) but significantly lower than the values obtained at post-operative Day 1 (P?=?0.013, P?=?0.002 and P?=?0.010, respectively). The densitometry value of the posterior layer over the annular diameters of 2 to 6?mm remained unchanged (from 9.4?±?0.7 to 9.1?±?0.7) over time (P?=?0.372). The efficacy and safety indices assessed at 12?months post-operatively were 1.04?±?0.27 and 1.19?±?0.23, respectively. The changes in IOP and ECD values were statistically insignificant (P?=?0.896 and P?=?0.968, respectively). CONCLUSION:ICL-V4c implantation may be safe and efficient for high ametropia correction. The corneal densitometry values obtained over the annulus of 0-6?mm increased slightly from before the operation to post-operative Day 1 and then decreased gradually, which indicates that ICL-V4c implantation may not compromise corneal clarity.
