Decreased visual acuity resulting from glistening and sub-surface nano-glistening formation in intraocular lenses: A retrospective analysis of 5 cases.

BACKGROUND: To report on five patients with decreased visual acuity due to glistening and severe sub-surface nano-glistening (SSNG) formation within their intraocular lenses (IOLs). DESIGN: Case reports and analysis of extracted IOLs. PARTICIPANTS AND SAMPLES: We report improved visual acuity when IOLs with severe glistening and SSNG were exchanged for clear IOLs in five patients. METHODS: Case reports. MAIN OUTCOME MEASURES: The main outcome measure was visual acuity. The secondary outcome measure was light transmission. Explanted IOLs were subjected to investigation. Pre- and postoperative slit lamp images of the anterior eye and microscopic images of the extracted IOLs were taken and compared. Light transmission of the IOL was measured using a double beam type spectrophotometer. An integrated value of the percentage light transmittance in the visible light spectrum was calculated. RESULTS: We report on five patients whose visual acuity improved when IOLs were exchanged because of severe glistening and SSNG. All of the affected IOLs were MA60BM (Alcon, Forth Wroth Texas, USA) and the original implantation had occurred over a range of 6-15 years prior to the IOL exchange. Light transmission was decreased in all affected lenses compared to a similar control IOL. CONCLUSIONS: Although only a few reports of cases in which glistening and SSNG have progressed to the level of decreased visual function have been published, the likelihood is that this phenomena will increase as the severity and incidence of these inclusions have been shown to increase with time. Appropriate evaluations of visual function in such patients are needed and consideration should be given to IOL exchange in symptomatic patients.

Impact of intraocular lens material and design on light scatter: In vitro study.

PURPOSE: To determine the typical in vitro straylight levels for intraocular lenses (IOLs) of different materials and designs. SETTING: Abbott Medical Optics, Inc., Groningen, the Netherlands. DESIGN: Experimental study. METHODS: Two optical bench setups were used to determine baseline straylight levels of IOLs placed in a saline-filled cuvette: one for forward scatter positions between 0.6 and 3.0 degrees and one for positions up to 22.0 degrees. Line-spread functions were measured using the small-angle setup, and scattered light intensity was measured using the wide-angle setup. From these measurements, the angular dependent straylight parameter was calculated. Ten IOLs of different materials (hydrophobic and hydrophilic) and designs (monofocal or diffractive multifocal and spheric or aspheric) were studied, and their measured straylight levels were compared with the levels in a 20-year-old and a 70-year-old healthy noncataractous human crystalline lens. RESULTS: Irrespective of the material or design, monofocal IOLs had straylight levels below or close to those of a 20-year-old human crystalline lens. Diffractive multifocal IOLs had straylight levels higher than those of monofocal IOLs but less than those of a 70-year-old human crystalline lens. With increasing angle, hydrophobic IOLs showed a gradual decrease in straylight level. After an initial decrease, hydrophilic IOLs showed an increase in straylight level for larger angles. CONCLUSIONS: The baseline straylight levels of IOLs were design and material dependent (hydrophobic < hydrophilic; monofocal < diffractive multifocal). Most monofocal IOLs had straylight levels below the levels in a 20-year-old human crystalline lens.

Comparison of visual results with accommodating intraocular lenses versus mini-monovision with a monofocal intraocular lens.

PURPOSE: To compare near vision and quality of vision after controlling for pseudoaccommodation in patients with single-optic accommodating intraocular lenses (IOLs) or monofocal IOLs targeted for mini-monovision. SETTING: Clinical practice. DESIGN: Prospective randomized controlled clinical trial. METHODS: Patients were randomized to bilateral implantation of the Crystalens HD silicone accommodating IOL, the Tetraflex acrylic accommodating IOL, or the Tecnis 1-piece monofocal (nonaccommodating) control IOL. The target refraction for the control group was mini-monovision (-0.25 diopter [D] and -0.75 D). In the accommodating IOL groups, manufacturer recommendations were followed; that is, a target refraction of mini-monovision (-0.25 D and -0.75 D) in the acrylic accommodating group and +0.25 D in the silicone accommodating group. Pupil size and anterior corneal spherical aberration were measured preoperatively. Main outcome measures were binocular target refraction corrected near vision and contrast sensitivity 3 months postoperatively. RESULTS: There were no statistically significant differences between the 3 groups in age, photopic or mesopic pupil size, anterior corneal spherical aberration, corneal astigmatism, or the power of the IOLs implanted. Binocular distance visual acuity at 4 m was 20/20(-) in all groups, intermediate vision was approximately 20/25, and near vision was 20/40 to 20/50. There were no statistically significant differences between the 3 groups in visual acuity or contrast sensitivity. CONCLUSION: Single-optic accommodating IOLs did not offer a significant advantage in near visual acuity over mini-monovision with a monofocal (nonaccommodating) IOL.

Personalized correction of spherical aberration in cataract surgery.

PURPOSE: To compare contrast sensitivity after phacoemulsification with implantation of the Tecnis intraocular lens (IOL) between patients with a selected preoperative corneal spherical aberration and patients without a selected amount of aberration. SETTING: Private practice, St. Catharines, Ontario, Canada. METHODS: Thirty-three cataract patients were divided into 2 groups. The first group (n = 13) included consecutive patients with a spherical aberration of at least +0.33 microm measured with the Oculus Easygraph. Consecutive patients meeting the inclusion criteria (n = 20) were included in the second group. All patients had phacoemulsification with implantation of the Tecnis IOL. After 3 to 5 weeks, contrast sensitivity was measured by sinusoidal grating charts for distance under photopic (85 cd/m2) and mesopic (3 cd/m2) conditions with optical correction in place. Five standard spatial frequencies were tested. RESULTS: All surgical procedures and postoperative courses were uneventful. The IOLs were in the bag without decentration or tilt. The mean preoperative spherical aberration was +0.370 microm +/- 0.024 (SD) in the first group and +0.291 +/- 0.081 microm in the second group (P = .0010). Patients in the first group had better contrast sensitivity than those in the second group. Statistically significant differences were detected at spatial frequencies of 6.0 cycles per degree (cpd) and 12 cpd under photopic conditions (P = .0267 and P = .0215, respectively) and mesopic conditions (P = .0356 and P = .0217, respectively). CONCLUSIONS: The Tecnis IOL has a negative spherical aberration of -0.27 microm. Targeting for a postoperative mean residual spherical aberration of approximately +0.10 microm by selecting patients according to their preoperative spherical aberration resulted in better contrast sensitivity.

Distribution of corneal spherical aberration in a comprehensive ophthalmology practice and whether keratometry can predict aberration values.

PURPOSE: To determine the spherical aberration of the cornea in the general population and whether keratometry readings are predictive of corneal spherical aberration values. SETTING: Private comprehensive ophthalmology practice. METHODS: Corneal spherical aberration and keratometry readings were measured in 696 normal eyes of patients presenting for ocular examination to a comprehensive ophthalmologist. The Easygraph (Oculus) was used to measure the corneal topography and keratometry readings in patients with healthy corneas. The analysis was performed using software in the Easygraph to determine the Zernike coefficients for each cornea. The keratometry and spherical aberration (Zernike coefficient Z(4)(0)) were then statistically analyzed. RESULTS: The corneal spherical aberration, analyzed by the Kolmogorov-Smirnov test for normality, fit a normal Gaussian distribution. The spherical aberration value was (+0.274 +/- 0.089) x 10(-3), measured at an optical zone of 6.0 mm. A very weak correlation was found between corneal spherical aberration and central keratometry readings of the cornea: Corneal spherical aberration = {0.017 x (mean keratometry) - 0.457} x 10(-3). CONCLUSIONS: The corneal spherical aberration distribution was a normal Gaussian curve. However, the mean value was significantly different when the sex of the patient was considered. Corneal keratometry readings could not be reliably used to predict corneal spherical aberration.

Endothelial cell loss after cataract phacoemulsification with Healon5 vs. I-Visc Phaco.

BACKGROUND: Healon5, the first viscoadaptive agent introduced in ophthalmic surgery, has been judged to be superior to Healon GV in protecting corneal endothelial cells. The purpose of this study was to compare the endothelial protective effects of I-Visc Phaco, a newer viscoadaptive agent, with those of Healon5 in cataract phacoemulsification. METHODS: A total of 96 unselected patients scheduled to undergo cataract surgery at a community-based hospital in St. Catharines, Ont., were assigned to receive I-Visc Phaco. This group was compared with 112 patients who had received Healon5 in a previous study by the author. The technique used to remove the cataract with phacoemulsification and insertion of an intraocular lens was the same in the two groups. Endothelial cell count and corneal thickness were measured preoperatively and 3 and 8 weeks postoperatively with a Konan noncontact specular microscope. One-way analysis of variance was used to analyse the data. RESULTS: Preoperatively there was no statistically significant difference between the Healon5 and I-Visc Phaco groups in age, eye operated, or endothelial cell count or corneal thickness. At 3 weeks there was no significant difference between the two groups in mean endothelial cell count (2110.2 [standard deviation (SD) 529.9] cells/mm2 vs. 2113.5 [SD 566.6] cells/mm2) or mean corneal thickness (586.2 microm [SD 46.73 microm] vs. 583.9 microm [SD 42.23 microm]). Similarly, there was no significant difference between the two groups in mean endothelial cell count (2113.3 [SD 496.6] cells/mm2 vs. 2145.5 [SD 573.1] cells/mm2) or mean corneal thickness (570.9 microm [SD 44.09 microm] vs. 574.4 microm [SD 40.73 microm]) at 8 weeks. INTERPRETATION: Results at 3 and 8 weeks postoperatively indicate that Healon5 and I-Visc Phaco protect the endothelium equally well during cataract phacoemulsification surgery.