Ghost-image analysis in phakic intraocular lenses with central hole as a potential cause of dysphotopsia.

PURPOSE

To analyse the optical effect of an artificial hole in the optic centre of posterior chamber phakic intraocular lenses.

SETTING

Institute of Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany.

DESIGN

Experimental simulation study.

METHODS

Four eye models with an ametropia of -4 D, -8 D, +4 D, and +8 D were created in the ray tracing software ASAP. Refractive correction of these models was implemented with a model of an Implantable Collamer Lens (ICL). Each eye was set up twice with 1 eye receiving a conventional ICL without a central hole and the second an ICL with a central hole. Ray bundles were traced for lateral visual field angles from 0 to 60 degrees in steps of 1 degree. Ray propagation and retinal illumination were then compared between the 2 ICL models.

RESULTS

All eye models showed ghost images originating from the anterior surface of the ICL. Eye models with the ICL with central hole showed additional light spots in the peripheral areas of the retina originating from reflections at the cylindrical wall of the central hole in the ICL. The average intensity of ghost images in the temporal retinal hemisphere was between 30 and 40 dB less than the maximum intensity of the primary image.

CONCLUSION

A central hole within a posterior chamber phakic intraocular lens may cause stray light and ghost images (positive dysphotopsia) although the on-axis visual quality of the eye with the ICL is mostly unaffected.

FINANCIAL DISCLOSURE

The authors have no financial interest in any of the material presented in this paper.