Optical Quality Of An Enhanced Monofocal Iol With Corneal Astigmatism

To evaluate how corneal astigmatism affects the optical quality of a (non-toric) enhanced monofocal intraocular lens (EM-IOL) (EM Isopure, BVI Medical, Belgium) in comparison to a standard monofocal lens of the same material and platform (Micropure, BVI Medical, Belgium).

- Group of Applied Optics and Image Processing, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Barcelona Tech, Spain.

- Optometry and Vision Department, Faculty of Optics and Optometry, Complutense University of Madrid, Spain.

The optical quality of the IOLs was studied in vitro in a model eye implemented on optical bench for 2.0, 3.0, and 4.5 mm pupils at the IOL plane. The model eye is specifically designed to closely resemble a natural, physiological eye. It is further equipped with an adaptive optics system, allowing for precise control over the possible existence of corneal astigmatism. We measured the effects of increasing corneal regular positive astigmatism (from 0.0 D to + 1.75 D, in 0.25 D steps) on the optical performance of the IOLs. From the through-focus (TF) images, the area under the MTF metric (MTFa) was calculated on the X and Y axes given its potential as a preclinical predictor of visual acuity (VA).

At pupils of 2.0 and 3.0 mm, the EM Isopure exhibited similar optical quality deterioration (i.e., MTFa decrease) to the reference monofocal IOL in the presence of corneal astigmatism. This degradation began at the minimum induced astigmatism level (0.25 D) and continued with increasing values. These results suggest a similar trend in visual acuity (VA) reduction and, consequently, limited tolerance to corneal astigmatism for patients implanted with the EM-Isopure and the monofocal Micropure, as long as the pupil diameter remains equal to or less than 3.0 mm. However, at a pupil diameter of 4.5 mm, the EM Isopure displayed a significantly greater decrease in optical quality compared to the reference monofocal IOL.

The reduction of optical quality of the (non-toric) EM Isopure IOL in presence of corneal astigmatism is similar to that of a reference monofocal Micropure IOL when tested in a model eye with pupils up to 3.0 mm. These results anticipate a similar trend in VA modification and, therefore, in limited tolerance to residual astigmatism, in patients implanted with EM Isopure compared to those implanted with monofocal Micropure. However, it would be necessary to contrast these results with clinical data from patients with larger pupils to observe how pupillary dynamics influence this group.