Changes in vaulting of myopic and toric implantable collamer lenses in different lighting conditions

Abstract

. Purpose: To evaluate the changes in vaulting of myopic and toric Implantable Collamer Lenses (ICLs) in different lighting conditions. Methods: Thirty‐seven eyes of 37 patients implanted with a myopic ICL and 26 eyes of 26 patients implanted with a toric ICL were examined using Visante optical coherence tomography (OCT) in photopic (257 lux) and mesopic (2 lux) conditions. Pupil diameter and distance changes between the ICL and adjacent intraocular structures were measured. Results: The mean horizontal pupillary diameters in mesopic conditions were 5.3 ± 0.9 (SD) mm. In photopic conditions, a mean decrease of –1.8 ± 0.6 mm [95% confidence interval (95% CI) −2.0 to −1.7; p < 0.0001] was observed. The mean distances between the ICL and the crystalline lens in mesopic conditions were 0.33 ± 0.17 mm. In photopic conditions, a mean decrease of −0.04 ± 0.06 mm (95% CI −0.05 to −0.02; p < 0.0001) in the ICL‐crystalline lens distance was found. There was a −0.02 ± 0.04 mm (95% CI −0.03 to −0.01; p = 0.0022) decrease in the anterior chamber depth and a 0.02 ± 0.06 mm (95% CI 0.002 to 0.032; p = 0.0275) increase in the distance between the cornea and the ICL. We found no difference in the change in vaulting between the two ICLs in different lighting conditions. Conclusion: There is a decrease in the central vaulting of myopic and toric ICLs in photopic conditions. This is due to both posterior movement of the ICL and anterior protrusion of the crystalline lens.

Dynamic Vaulting Changes in V4c versus V4 Posterior Chamber Phakic Lenses Under Differing Lighting Conditions

“…11 A significant mean reduction in vaulting (À40 mM) in eyes implanted with V4 ICLs also has been reported under photopic conditions of 257 lux. 13 Consistent with these 2 studies, in the eyes implanted with V4 ICLs in our study, a comparable reduction in vaulting (À88.6 mM) was observed, showing the highest amount of vaulting changes between photopic and mesopic conditions. A possible explanation is that the light intensity provided by a light source such as a penlight or room light may affect changes in vaulting, based on previous studies that showed increased light stimulus intensity was associated with an increase in direct light reflex amplitude and the maximum rate of constriction.…”

“…Additionally, anterior protrusion or posterior movement of the crystalline lens might follow, all of which have been demonstrated previously in eyes implanted with conventional ICLs. 11,13 However, our results in eyes implanted with V4c ICLs did not support light-induced movement of the crystalline lens, which was proven by an unchanging ACD according to differing lighting conditions. Based on these results, it is highly probable that the backward movement of the V4c ICL toward the anterior surface of the crystalline lens, induced by constriction of the pupil under photopic conditions, could be the main contributor to dynamic changes in vaulting.…”

“…11,13 In 1 study that included 10 eyes implanted with V4 ICLs and 3 eyes implanted with V3 models, a significant mean reduction in vaulting (À73 mM) was observed under photopic conditions with miosis of the pupil; the result was induced by shining a penlight into the contralateral eye. 11 A significant mean reduction in vaulting (À40 mM) in eyes implanted with V4 ICLs also has been reported under photopic conditions of 257 lux.…”

“…11,12 On the other hand, pupil constriction is induced under photopic conditions merely via the light reflex, which is mediated by retinal photoreceptors and subserved by 4 neurons (the sensory, internuncial, preganglionic motor, and postganglionic neurons), finally causing the ICL to move toward the crystalline lens. 11,13,14 Studies evaluating changes in vaulting of the ICL under differing lighting conditions showed a significant decrease in central vaulting under photopic conditions. 11,13 Recently, the V4c ICL (CentraFLOW technology, STAAR Surgical) was designed with a 360 mm central hole to allow for the natural flow of aqueous humor without the need for iridotomy.…”

“…11,13,14 Studies evaluating changes in vaulting of the ICL under differing lighting conditions showed a significant decrease in central vaulting under photopic conditions. 11,13 Recently, the V4c ICL (CentraFLOW technology, STAAR Surgical) was designed with a 360 mm central hole to allow for the natural flow of aqueous humor without the need for iridotomy. The V4c ICL has shown clinical outcomes comparable to those of the conventional V4 ICL.…”