Abstract
PurposeTo compare aqueous humour (AH) dynamics in the presence of a precrystalline (Implantable Collamer Lens®; ICL) or iris-fixed (Artiflex®) phakic intraocular lens (PIOL).MethodsBy computational fluid dynamics simulation, AH flow was modelled through a peripheral iridotomy (PI) or central lens hole (both 360 μm) in the presence of an Artiflex or ICL lens, respectively. The impacts of AH flow were then determined in terms of wall shear stress (WSS) produced on the endothelium or crystalline lens. Effects were also modelled for different scenarios of pupil diameter (PD 3.5 or 5.5 mm), ICL vault (100, 350, 800 μm) and number of Artiflex iridotomies (1 or 2) and location (12 or 6 o’clock).ResultsFor a PD of 3.5 mm, AH volumes flowing from the posterior to the anterior chamber were 37.6% of total flow through the lens hole (ICL) and 84.2% through PI (Artiflex). For an enlarged PD (5.5 mm), corresponding values were 10.3% and 81.9% respectively, so PI constitutes a very efficient way of evacuating AH. Central endothelial WSS in Pa was lower for the large vault ICL and the Artiflex (1−03 and 1.1−03 respectively) compared to the PIOL-free eye (1.6−03). Crystalline lens WSS was highest for the lowest vault ICL (1−04).ConclusionsAH flow varied according to the presence of a precrystalline or iris-fixed intraocular lens. Endothelial WSS was lower for an implanted ICL with large vault and Artiflex than in the PIOL-free eye, while highest crystalline WSS was recorded for the lowest vault ICL.
Highlights
For a pupil diameter (PD) of 3.5 mm, aqueous humour (AH) volumes flowing from the posterior to the anterior chamber were 37.6% of total flow through the lens hole (ICL) and 84.2% through peripheral iridotomy (PI) (Artiflex)
AH flow varied according to the presence of a precrystalline or iris-fixed intraocular lens
Endothelial wall shear stress (WSS) was lower for an implanted ICL with large vault and Artiflex than in the phakic intraocular lens (PIOL)-free eye, while highest crystalline WSS was recorded for the lowest vault ICL
Summary
Two of the most popular options are the placement of a posterior chamber (PC) or anterior chamber (AC) iris-fixed phakic intraocular lens (PIOL) such as the implantable collamer lens (ICL, STAAR Surgical AG, Nidau, Switzerland)1 [1,2] or Artiflex (Ophthec, The Netherlands), respectively [3,4].Despite infrequent complications, these PIOLs have common potential risks such as ocular hypertension, pupillary block, pigment dispersion, endothelial damage, angle narrowing, and cataracts [3,4,5,6,7,8,9,10].An implanted PIOL is an obstacle that hinders the passage of AH from the PC to the AC through the pupil, forcing the AH to redistribute. Two of the most popular options are the placement of a posterior chamber (PC) or anterior chamber (AC) iris-fixed phakic intraocular lens (PIOL) such as the implantable collamer lens (ICL, STAAR Surgical AG, Nidau, Switzerland)1 [1,2] or Artiflex (Ophthec, The Netherlands), respectively [3,4] Despite infrequent complications, these PIOLs have common potential risks such as ocular hypertension, pupillary block, pigment dispersion, endothelial damage, angle narrowing, and cataracts [3,4,5,6,7,8,9,10]. In the presence of a PIOL, reduced AH could directly cause ocular hypertension or mechanical trauma, and indirectly may lead to the development of cataract or endothelial damage by compromising oxygen and nutrient delivery to the cells
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