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Patients report high satisfaction with an updated implantable collamer lens (ICL), and objective testing shows patients can achieve high visual quality with the devices, according to a report published in BMC Ophthalmology. Issues such as vertical tilt, total decentration, horizontal decentration, and vertical decentration had no significant correlation with visual symptom scores, according to the study. The devices, used in patients with high myopia, have been approved in the US since 2005.
This observational study included 135 eyes of 69 patients at Fudan University Eye and ENT Hospital, Shanghai, China. Fifty-six women and 13 men participated, with an age range of 20 to 40 years and mean age of 28.88±5.46 years. Spherical equivalent (SE) spanned -4.0 D to -18.5 D and averaged -10.16±2.99 D. Forty-six eyes received spherical lenses and 89 received toric ICLs.
At 6 months, mean uncorrected distance visual acuity (UDVA) was 1.12±0.23, corrected distance visual acuity (CDVA) measured 1.18±0.19, and mean SE was -0.13±0.44. Despite no substantial changes in total higher-order and spherical aberrations, the analysis found significantly increased values for coma (P =.003) and trefoil (P =.000).
Postoperative tilt change was 4° or smaller for 91.85% of patients, and all eyes were within 5°. Similarly, decentration was 0.5 mm or less for 98.5% of patients, with the maximum value being 0.6 mm. Total, horizontal, and vertical tilt or decentration did not show significant association with postoperative UDVA, CDVA, or occurrence of aberrations (P >.05). While the amount of tilt and decentration was small, frequency of visual symptoms correlated to total tilt (P <.001) and horizontal tilt (P =.003), as well as to bothersomeness (both P <.001) on the quality of vision (QOV) instrument.
Halo was the most often-experienced visual symptom (93.33%), but only reported to be more than mildly bothersome by 8.15% in the cohort. The second-most frequent symptom was glare for 54.81%, but exceeded mild intensity in just 1.48%; and third-most was blurred vision by 41.48%, including more than mild bother in 1.38%. Overall, satisfaction with the device was high; 97.04% of participants gave it ratings of 8 or higher out of 10.
The ICL V4c has a central 360 μm hole that allows for flow of aqueous humor, and evaluation of position or tilt changes. Previous research suggests there is a threshold for tilt and decentration in aspheric ICLs — above which visual function can be impacted. Also, studies indicate that halo may be caused by light reflecting on the inner surface of the central hole and posterior plane of an ICL, or that off-axis light can boost intraocular light scattering; thus symptoms are more evident with greater tilt.
The short follow-up time did not allow for analysis of time-dependent changes in tilt and decentration, which limited the study. Also, QOV score reflected the combination of all 10 perceived symptoms. Conversely, a strength comprised data adjustment for preoperative refraction, age, and eye laterality. Prior studies of ICL decentration have been in vitro, although this investigation is first to offer data in an in vivo setting.
Reference
Niu L, Zhang Z, Miao H, et al. Effects of tilt and decentration of Visian Implantable Collamer Lens (ICL V4c) on visual quality: an observational study. BMC Ophthalmol. Published online July 5, 2022. doi:10.1186/s12886-022-02499-4
