A contralateral eye study comparing apodized diffractive and full diffractive lenses: wavefront analysis and distance and near uncorrected visual acuity.

PURPOSE: To evaluate intraindividual visual acuity, wavefront errors and modulation transfer functions in patients implanted with two diffractive multifocal intraocular lenses. METHODS: This prospective study examined 40 eyes of 20 cataract patients who underwent phacoemulsification and implantation of a spherical multifocal ReSTOR intraocular lens in one eye and an aspheric Tecnis ZM900 multifocal intraocular lens in the other eye. The main outcome measures, over a 3-month follow-up period, were the uncorrected photopic distance and near visual acuity and the defocus curve. The visual acuity was converted to logMAR for statistical analysis and is presented in decimal scale. The wavefront error and modulation transfer function were also evaluated in both groups. RESULTS: At the 3-month postoperative visit, the mean photopic distance uncorrected visual acuity (UCVA) was 0.74 +/- 0.20 in the ReSTOR group and 0.76 +/- 0.22 in the Tecnis group (p=0.286). The mean near UCVA was 0.96 +/- 0.10 in the ReSTOR group and 0.93 +/- 0.14 in the Tecnis group (p=0.963). The binocular defocus curve showed measurements between the peaks better than 0.2 logMAR. The total aberration, higher-order aberration and coma aberration were not significantly different between the groups. The spherical aberration was significantly lower in the Tecnis group than in the ReSTOR group. (p=0.004). Both groups performed similarly for the modulation transfer function. CONCLUSION: The ReSTOR SN60D3 and Tecnis ZM 900 intraocular lenses provided similar photopic visual acuity at distance and near. The diffractive intraocular lenses studied provided a low value of coma and spherical aberrations, with the Tecnis intraocular lens having a statistically lower spherical aberration compared to the ReSTOR intraocular lens. In the 5 mm pupil diameter analyses, both intraocular lens groups showed similar modulation transfer functions.

Mini-rhexis for white intumescent cataracts.

PURPOSE: To compare the intraoperative safety of two techniques of capsulorhexis for intumescent white cataracts: traditional one-stage continuous curvilinear capsulorhexis and two-stage continuous curvilinear capsulorhexis. METHODS: This prospective comparative randomized study included two groups: the 1-CCC group (11 patients) received traditional one-stage continuous curvilinear capsulorhexis with 5-6 mm diameter, and the 2-CCC (13 patients) group received a deliberately small continuous curvilinear capsulorhexis that was secondarily enlarged, or a two-stage continuous curvilinear capsulorhexis. Patients were stratified according to cataract subset, which was characterized echographically. Six patients were considered as type 1, fifteen as type 2 and three as type 3. Type 1 included intumescent white cataracts with cortex liquefaction and extensive internal acoustic reflections, type 2 included white cataracts with voluminous nuclei, a small amount of whitish solid cortex, and minimal internal acoustic reflections, and type 3 included white cataracts with fibrous anterior capsules and few internal echo spikes. RESULTS: With the one-stage technique, 46.15% of patients had leakage of the liquefied cortex; in addition, the surgeon perceived high intracapsular pressure in 61.53% of cases. Anterior capsule tears occurred in 23.07% of cases, discontinuity of capsulorhexis in 30.79% of cases and no posterior capsular rupture occurred. With the two-stage technique, leakage of the liquefied cortex occurred in 45.45% of cases; additionally, the surgeon perceived high intracapsular pressure in 36.36% of cases. No anterior capsule tears, discontinuity of capsulorhexis or posterior capsular rupture occurred. Considering each cataract subset, there was a higher incidence of leakage for type 2 as compared to types 1 and 3. CONCLUSIONS: Two-stage continuous curvilinear capsulorhexis helps prevent unexpected radial tears of the initial capsulotomy from high intracapsular pressure, sudden radialization of the CCC and other intraoperative complications due to high intracapsular pressure, thus providing a safe cataract surgery in cases of white cataracts. These findings were supported by ultrasonography.