Posters

Retinal image magnification and distortion in the pseudophakic eye

Poster Details

First Author: H.Ginis GREECE

Co Author(s): G. Rallatos   P. Zafirakis                 

Abstract Details

Purpose:

The purpose of the study was to investigate the geometric properties of the peripheral retinal image in pseudophakic eyes. Specifically, to investigate whether there is magnification and distortion and correlate these properties with the power and effective lens position (ELP) of the implanted intraocular lenses (IOLs).

Setting:

Athens Eye Hospital, Glyfada, Greece.

Methods:

Fundus photography (Cobra HD, SCO, Italy) is performed routinely in all patients presented for cataract evaluation at Athens Eye hospital. We recruited fourty-eight (48) patients that underwent cataract surgery, implanted with monofocal IOLs (range: 18 to 26 D, mean 21.4D), for which retinal features such as vessel bifurcations were clearly visible in the preoperative fundus images. Fundus photography was repeated one month postoperatively. Each images pair was comparatively analysed using a purposely-written computer script using MATLAB (MathWorks, Natick, MA, USA). The script allowed image superposition (registration), rotation and calculation of the relative displacement of retinal features.

Results:

Image analysis revealed a radial displacement of the retinal features consistent with image magnification. The radial displacement ranged from 0 to 2.5 degrees (mean:1.12, SD: 0.58). The magnification was not constant at all field angles indicating a positive (Pincushion type) distortion.The findings were consistent with optical modelling analysing the relationship between image magnification, image distortion and IOL power and ELP.

Conclusions:

The present study revealed image magnification and distortion in the central sixty degrees of the visual field in pseudophakic eyes. The measured magnification is unlikely to have any practical implications for central vision. However, since peripheral image can be distorted by several degrees. It remains to be investigated whether this phenomenon affects the peripheral vision of pseudophakic patients.

Financial Disclosure:

None