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Published on: September 20, 2024
Combining small aperture approach and toric correction for irregular astigmatism management
Hyeck-Soo Son1, Asu Rayamajhi, Ava Niknahad
1From The David J. Apple Center for Vision Research, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany (Son, Rayamajhi, Niknahad, Khoramnia, Auffarth, Augustin, Friedrich, Łabuz); Light Technology Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany (Rayamajhi); Johns Hopkins School of Medicine, Baltimore, Maryland (Niknahad); Department of Ophthalmology, University Hospital of Carl Gustav Carus Dresden, Germany (Khoramnia).
Purpose:
To investigate the potential of a hybrid intraocular (IOL) design featuring both small-aperture and toric elements to address the limitations of irregular astigmatism in cataract surgery. IOLs featuring a small-aperture have shown promise in managing such cases through the "pinholde effect" yet they do not correct the underlying astigmatic power.
Setting:
David J. Apple Laboratory for Ocular Pathology, Heidelberg, Germany.
Design:
Experimental study.
Methods:
A retrospective analysis of 22 eyes with irregular astigmatism was conducted using semipersonalized eye models derived from Pentacam tomography data. Simulations were performed in OpticStudio to evaluate 3 IOL systems: a toric IOL, a small-aperture, and a combined small-aperture + toric IOL. Image quality was assessed using Strehl ratio (SR) and root mean square (RMS) error. Landolt C simulations and correlation analyses were also performed.
Results:
The hybrid IOL significantly outperformed the toric and small-aperture IOLs alone, achieving mean SR of 0.80 ± 0.17 (vs 0.10 ± 0.07 and 0.20 ± 0.19, respectively, P < .001) and the lowest RMS error (0.07 μm, P < .001). Simulations demonstrated superior visual quality and less sensitivity to corneal asymmetry. R2 analyses confirmed a strong association between corneal astigmatism and improved optical quality in the combined model.
Conclusions:
Integrating a toric correction within a small-aperture optic yields superior optical performance in irregular astigmatism simulations. In clinical practice, combining sulcus-fixated pinhole implants with toric posterior-chamber IOLs or sulcus-fixated toric lenses with a small-aperture posterior-chamber IOL may achieve better outcomes in complex corneal profiles.
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