Functional Acuity Contrast Test Research Articles

Retinal image contrast and functional visual performance with aspheric, silicone, and acrylic intraocular lenses: prospective evaluation

Purpose To compare the effects of an aspheric intraocular lens (IOL) (Tecnis Z-9000, Pharmacia Corp.) with those of conventional silicone (AA4207VF, Staar Surgical) and acrylic (AcrySof® SA60AT, Alcon Surgical) lenses on retinal imaging and functional visual performance. Setting Eye Laser Center, Tucson, Arizona, USA. Methods In this prospective study, 221 eyes of 156 patients were randomly assigned to receive 1 of 3 IOLs. Visual acuity was measured preoperatively and 1 day, 1 and 3 weeks, and 1, 3, and 6 months postoperatively. Fundus photography and photopic and mesopic functional acuity contrast testing were performed preoperatively and 3 months postoperatively. Results The differences in the preoperative and postoperative spherical and astigmatic refractive errors and best corrected visual acuity among groups were not statistically significant. The postoperative uncorrected visual acuity was best in the aspheric group in the first month. Functional acuity contrast testing showed the aspheric IOL group had a 38% to 47% increase in photopic vision, 38% in photopic with glare, 43% to 100% in mesopic, and 9% to 100% in mesopic with glare. There was no increase in photopic vision in the acrylic group but increases of 38% in photopic with glare, 25% to 50% in mesopic, and 36% to 50% in mesopic with glare. The spherical silicone IOL group had no increase in contrast testing from preoperatively. Digital analysis of retinal imaging showed increased threshold luminance levels in the aspheric group (range 116 to 208 cd/m 2) and a 4-fold increase in image contrast. Conclusions All 3 IOLs led to improved visual acuity after cataract surgery. The aspheric IOL provided a significant improvement in retinal image contrast and visual performance measured by visual acuity and functional acuity contrast testing. This improvement was greatest in night vision and night vision with glare compared to the performance of conventional spherical silicone and acrylic IOLs.

Distance and near contrast sensitivity function after multifocal intraocular lens implantation

Purpose To evaluate contrast sensitivity at distance and near after multifocal intraocular lens (IOL) implantation. Setting Ophthalmologic Institute of Alicante, University Miguel Hernández, Alicante, Spain. Methods Contrast sensitivity was measured with the Stereo Optical Functional Acuity Contrast Test at distance and near in 21 patients with a refractive multifocal IOL (Array SA-40N, AMO). A control group with a monofocal IOL (SI-40NB, AMO) was also studied to allow comparison of results. Contrast sensitivity was measured 1, 3, 6, 12, and 18 months after IOL implantation. Results There was a statistically significant greater reduction in contrast sensitivity at distance at all spatial frequencies in the multifocal group than in the monofocal group during the first month. At 3 months, contrast sensitivity at 12 and 18 cycles per deg remained reduced in the multifocal group; contrast sensitivity at the other frequencies did not differ from that in the monofocal group ( P > 0.1). At 6, 12, and 18 months, contrast sensitivity at all spatial frequencies was not significantly different between groups ( P > 0.1). There was a statistically significant greater reduction in near contrast sensitivity in the multifocal group than in the monofocal group at all spatial frequencies during the first and third month after surgery ( P < .01). No statistically significant differences were found between groups after 6 months ( P > 0.1). Contrast sensitivity at distance and near in the multifocal group improved over time ( P < .01). Conclusions The Array IOL provided contrast sensitivity at distance comparable to that obtained with the monofocal IOL between 3 and 6 months after implantation. Near contrast sensitivity improved over time but was always lower than at distance and in the monofocal near-corrected patients, which is acceptable to avoid near visual function degradation.