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Pupil dynamics

Maximilian Hammer Maximilian Hammer Follow Nov 26, 2021 · 2 mins read
Pupil dynamics
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Heidelberg, 26.11.2021. It is with great joy that we would like to share with you that our paper has recently been published in Nature’s Scientific Reports - on our study of the effect on pupil size after three different strategies for IOL fixation.

Yanxiu Sun, Maximilian Hammer, Timur M Yildirim, Ramin Khoramnia & Gerd U Auffarth Pupil dynamics after in-the-bag versus anterior and retropupillary iris-fixated intraocular lens implantation. Sci Rep 11, 21436 (2021).

The background

In general, there are two applications for implanting Iris-claw intraocular lenses (IOLs ). When the lenses are fixed anteriorly this corrects a patient’s refractive error. In the second indication, the lens is fixed posteriorly to treat aphakia, or a late-onset dislocation or subluxation of an IOL that was fixed in the capsule. Regardless of where the lens is placed, the enclavation of the iris tissue opens the possibility of restricting pupil motility.

What we did

In this study, we investigated postoperative pupil size at three different levels of illumination for anterior and posterior iris-fixated IOLs and we compared that to pupil size after in-the-bag IOL implantation. We analyzed seventy eyes in three groups: 22 of 11 patients in the anterior iris-fixation group, 22 eyes of 20 patients in the posterior iris-fixation group, and 26 eyes of 13 patients in the in-the-bag group.

We measured pupil size using a Procyon P2000 pupillometer (Procyon Instruments Ltd, London, United Kingdom) at scotopic (0.04 lx), low-mesopic (0.4 lx) and high-mesopic (4 lx) light conditions. All the groups were measured 6-months after surgery and we did preoperative measurements for the IFPH- and IB-group.

What we found

Both groups, those that underwent in-the-bag fixation as well as those with anterior iris-fixated IOLs, showed a smaller scotopic pupil size postoperatively, when compared to preoperative values. Postoperatively, the group that underwent posterior iris-fixated IOL implantation showed a significantly smaller scotopic pupil size compared to the other two groups.

Legend: IFRP – retropupillary iris-claw fixation, IB – In-the-bag, IFPH- anterior iris-fixation

In Summary

While all three IOL fixation strategies do not impair the constriction of the pupil in normal light conditions, we did see differences at scotopic illumination. The retropupillary iris-fixation strategy showed smaller scotopic pupil sizes when compared to the in-the-bag group with a similar age. Prof. Gerd Auffarth commented,“It is noteworthy that neither of the surgical techniques for iris fixation seems to impair the constriction of the pupil in normal light conditions. But this points to the need for more studies where we assess pre- and post-operative pupil size of patients undergoing IFRP as well as the relation between pupil dynamic measurements and patient reported outcomes.”

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Maximilian Hammer
Written by Maximilian Hammer Follow
Maximilian Hammer is an Ophthalmology Resident at the University Eye Clinic Heidelberg and a Research Scientist at the David J Apple Laboratory.