Posters

Evaluation of light distortion analysis as an indicator of visual quality after refractive lens exchange with a diffractive multifocal intraocular lens with and without toricity

Poster Details

First Author: P.Brito PORTUGAL

Co Author(s):    M. Monteiro   H. Neves   J. González-Meijome   J. Salgado-Borges     

Abstract Details

Purpose:

Modern refractive surgery techniques aim at correcting refractive errors with the highest level of spectacle independence. Multifocal intraocular lenses (IOL) accomplish such goal by providing focal points for distance and near vision, but good results in terms of visual acuity do not always correspond to an acceptable visual quality, namely due to the presence of bothersome photic phenomena. Therefore, we used a prototype device to study the perception of light distortion after refractive lens exchange with diffractive multifocal IOLs. By correlating the distortion indices with the visual and refractive outcomes and by comparing with cases implanted with a monofocal IOL we intend to elaborate on light distortion as an indicator of overall visual quality.

Setting:

Clínica Oftalmológica das Antas and Clínica Oftalmológica Prof. Salgado Borges Porto, Portugal

Methods:

This retrospective study included 66 eyes of 33 patients who undergone uneventful refractive lens exchange (RLE) with implantation of AT LISA 839M (group 2) or AT LISA 909MP (group 3) if corneal astigmatism higher than 0.75D was present. IOL power was determined using optical biometry. All cases with a minimum follow-up time of 3 months, were sequentially scheduled for a postoperative complete ophthalmological examination. Visual and refractive outcomes were analyzed, namely uncorrected distance visual acuity (UDVA), best corrected distance visual acuity (BCDVA), uncorrected near visual acuity (UNVA), preoperative refractive error and postoperative residual refractive error. All included cases underwent evaluation with the Light Distortion Analyzer device (University of Minho, Portugal) in order to quantify light distortion indices. A control group was included consisting of healthy individuals with visually significant cataract, submitted to phacoemulsification and implantation of a monofocal aspheric IOL (group 1). Additionally, all cases were questioned on the presence and severity of positive dysphotopsia.

Results:

All 3 groups achieved a significant improvement in UDVA (p<0.001) and BCDVA (p=0.001) and no significant differences were found in distance visual outcomes between the 3 groups. Mean UNVA was 0.12 LogMAR in group 2 and 0.13 logMAR in group 3. No significant difference in UNVA was seen between the two AT LISA groups. A postoperative refractive sphere <0.50D was seen in 57.8% of cases, while 86.7% of cases implanted with the 909MP obtained a residual refractive cylinder <1.00D. Mean light distortion index (DIX) was significantly higher in the AT LISA groups (46.9% and 53.5% for group 2 and 3) than in the monofocal group (23.9%) (p<0.001), but no correlation was found between DIX and UDVA. A significant correlation was found between DIX and residual refractive error, for all 3 groups (p<0.001). All cases in groups 2 and 3 reported significantly increased haloes, but such symptom was well tolerated.

Conclusions:

The studied AT LISA IOLs provided excellent UDVA and functional UNVA. The 909MP is effective in correcting refractive astigmatism, while providing visual outcomes as favorable as the 839MP. The fact that distortion indices were higher in the diffractive IOL groups, indicates that the LDA device may be a useful adjunct in the evaluation of overall visual quality obtained with different multifocal IOLs. FINANCIAL INTEREST: NONE