Effect of a yellow intraocular lens on scotopic vision, glare disability, and blue color perception.

PURPOSE: To compare the photopic and scotopic contrast sensitivity with and without glare as well as blue color perception between eyes with an AcrySof SN60AT Natural intraocular lens (IOL) (Alcon Laboratories Inc.) and eyes with a conventional AcrySof SA60AT IOL. SETTING: Ankara University School of Medicine, Department of Ophthalmology, Ankara, Turkey. METHODS: Right eyes of 38 patients with an AcrySof Natural IOL and right eyes of 38 age-matched patients with a conventional AcrySof SA60AT IOL were included in a study. Contrast sensitivity was measured with the Functional Acuity Contrast Test under photopic conditions. Scotopic contrast sensitivity in the presence or absence of glare was measured using the Mesotest II (Oculus GmbH). Blue-green color vision was evaluated with the Moreland equation of the HMC Anomaloskop MR (Oculus GmbH). RESULTS: The mean age of patients was 66.6 years +/- 8.2 (SD) in the Natural IOL group and 66.4 +/- 8.0 years in the conventional IOL group. There was no statistically significant difference in photopic contrast sensitivity, scotopic contrast sensitivity with and without glare, or disability glare between the 2 groups (P>.05). Photopic and scotopic contrast sensitivity with and without glare significantly decreased with age in both groups (P<.01). There was no statistically significant difference in anomaloscope scores between the 2 groups (P>.05). The Moreland middle match point showed a significant shift toward blue with age in both groups (P<.01). CONCLUSIONS: The AcrySof SN60AT Natural IOL provided contrast sensitivity under photopic and scotopic conditions (with and without glare) and blue color perception comparable that obtained with the AcrySof SA60AT IOL. Scotopic vision and blue color discrimination decreased with age with both IOLs.

Biocompatibility of Intraocular Lenses.

The performance of an intraocular lens is determined by several factors such as the surgical technique, surgical complications, intraocular lens biomaterial and design, and host reaction to the lens. The factor indicating the biocompatibility of an intraocular lens is the behavior of inflammatory and lens epithelial cells. Hence, the biocompatibility of intraocular lens materials is assessed in terms of uveal biocompatibility, based on the inflammatory foreign-body reaction of the eye against the implant, and in terms of capsular biocompatibility, determined by the relationship of the intraocular lens with residual lens epithelial cells within the capsular bag. Insufficient biocompatibility of intraocular lens materials may result in different clinical entities such as anterior capsule opacification, posterior capsule opacification, and lens epithelial cell ongrowth. Intraocular lenses are increasingly implanted much earlier in life in cases such as refractive lens exchange or pediatric intraocular lens implantation after congenital cataract surgery, and these lenses are expected to exhibit maximum performance for many decades. The materials used in intraocular lens manufacture should, therefore, ensure long-term uveal and capsular biocompatibility. In this article, we review the currently available materials used in the manufacture of intraocular lenses, especially with regard to their uveal and capsular biocompatibility, and discuss efforts to improve the biocompatibility of intraocular lenses.

Superoxide dismutase activity in the lens capsule of patients with pseudoexfoliation syndrome and cataract.

PURPOSE: To evaluate the activity of the antioxidative enzyme superoxide dismutase (SOD) in the anterior lens capsule of patients with cataract complicating pseudoexfoliation syndrome (PEX) in an attempt to determine the role of the oxidative mechanisms in the etiopathogenesis of this disorder. SETTING: Departments of Ophthalmology and Biochemistry, Ankara University School of Medicine, Ankara, Turkey. METHODS: At the beginning of phacoemulsification surgery, the anterior lens capsules in 21 eyes with PEX and cataract (group A) and those in 24 eyes with cataract alone (group B) were collected with continuous curvilinear capsulorhexis and were frozen at -20 degrees C. At the time of analysis, the specimens were thawed and centrifuged and the supernatants of the homogenate obtained from the samples were analyzed for the activity of the enzyme SOD. RESULTS: The mean age of patients was 74.8 years +/- 5.5 (SD) in group A and 71.7 +/- 5.6 years in group B. The specific activity of SOD was 17.6 +/- 10.8 IU/mg and 4.36 +/- 1.80 IU/mL in group A and 9.9 +/- 12.9 IU/mg and 2.71 +/- 2.61 IU/mL in group B. Superoxide dismutase activity was significantly higher in group A patients than in group B patients (P = .022 and P = .011, respectively). CONCLUSIONS: The increase in SOD activity in the lens capsule of patients with PEX and cataract suggests that oxidative mechanisms play a role in the etiopathogenesis of cataract in PEX. This suggests that SOD activity may be increased as a compensatory mechanism to eliminate this oxidative stress.

Drug-induced intraocular lens movement and near visual acuity after AcrySof intraocular lens implantation.

PURPOSE: To evaluate the factors influencing AcrySof intraocular lens (IOL) (Alcon Laboratories) movement and near visual acuity after cyclopentolate 1% and pilocarpine 2%. SETTING: Department of Ophthalmology, University of Ankara, Ankara, Turkey. METHODS: Thirty eyes of 22 patients with AcrySof IOL implantation were included in this prospective study. Near visual acuity (Jaeger) at 35 cm through best distance correction without an add and pupil diameter were measured and correlated with anterior chamber depth (ACD) measured with ultrasound biomicroscopy (UBM) after application of cyclopentolate 1% and pilocarpine 2%, respectively. The magnitude of the change in the ACD was correlated with the accommodation amplitude, patient age, time interval between surgery and imaging, preoperative axial length, capsulorhexis diameter, ACD during cycloplegia, IOL diameter, and presence of posterior capsule opacification (PCO). RESULTS: Near visual acuity significantly decreased after application of cyclopentolate 1% and increased after application of pilocarpine 2% (P < .001) in all eyes. The IOL moved anteriorly in 8 (26%) eyes and posteriorly in 22 (74%) eyes after pilocarpine 2%. There was no correlation between the ACD and near visual acuity under cyclopentolate 1% (r = 0.06, P > .05) or pilocarpine 2% (r = 0.04, P > .05). There was a moderate correlation between the anterior IOL movement and accommodation amplitude (P < .05, r = 0.42). There was no correlation between the magnitude of the IOL movement and patient age, time interval between surgery and imaging, the preoperative axial length, capsulorhexis diameter, ACD during cycloplegia, IOL diameter, and the presence of PCO (P > .05). CONCLUSIONS: There was better near visual acuity in all eyes with the AcrySof MAIOL, although most IOLs move slightly backward after of pilocarpine 2%. This points out pseudoaccommodation rather than pseudophakic accommodation. Ultrasound biomicroscopy is useful in determining the ACD and the relation between the IOL and the surrounding tissues after cataract surgery.

Effect of four different intraocular lenses on posterior capsule opacification.

AIM: To evaluate the impact of 4 different intraocular lenses (IOLs) on posterior capsule opacification (PCO) by comparing the neodymium: yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy rates. METHODS: This retrospective study included 4970 eyes of 4013 cataract patients who underwent phacoemulsification and IOL implantation between January 2000 and January 2008 by the same surgeon at one clinic. Four different IOLs were assessed. The outcome parameter was the incidence of Nd:YAG laser posterior capsulotomies. RESULTS: An Nd:YAG laser posterior capsulotomy was performed in 153 (3.07%) of the 4970 eyes. The mean follow-up time was 84mo for all of the IOL groups. The percentage of eyes developing PCO was significantly greater for the acrylic hydrophilic IOLs than for the hydrophobic IOLs, although eyes with acrylic hydrophilic IOLs did not require Nd:YAG laser capsulotomy as soon as eyes with acrylic hydrophobic IOLs. There was no difference between the long-term PCO rates when 1- and 3-piece acrylic hydrophobic IOLs were compared or when IOLs made of the same material but with different haptic angles were compared. CONCLUSION: In this study, eyes with acrylic hydrophilic IOLs were more likely to develop PCO than those with acrylic hydrophobic IOLs. The lens design (1-piece versus 3-piece and varying haptic angles) did not affect the PCO rate.

May nitric oxide molecule have a role in the pathogenesis of human cataract?

Recent studies have shown that nitric oxide molecule may have a role in the development of cataract. In this study, we measured the levels of a nitric oxide metabolite (nitrite) in the cataractous and normal human lenses. A modified Griess assay was used to determine the nitrite levels in the lenses as a measure of nitric oxide, based on the spectrophotometric method. Nitrite was detected in 26 (44.1%) cataractous lenses and was found below the detection limit in 33 (55.9%) cataractous lenses. Mean nitrite levels in cataractous lenses (2.77+/-5.26nmol/100mg) was found higher than the normal lenses (0.77+/-0.79nmol/100mg) but this increase was not statistically significant. Comparison of nitrite levels among lenses with various types of cataracts revealed higher levels in lenses with posterior subcapsular cataracts. Hypertensive patients had also significantly higher nitrite levels in their cataractous lenses. The increased levels in the cataractous lenses display a possible role of nitric oxide in the pathogenesis of cataract in human eyes.

Effects of intracameral lidocaine on ocular tissues.

PURPOSE: To investigate the ultrastructural changes in iris and corneal tissue induced by intracameral 1% lidocaine infusion applied during lens extraction in a rabbit model. METHODS: The study was conducted using New Zealand rabbits. Eight rabbits received 0.2 mL 1% lidocaine hydrochloride intracamerally and lens extraction was performed, keeping the posterior capsule intact. After lens extraction, cornea and iris tissue samples were obtained for electron microscopy. Eight eyes were included as a control group. RESULTS: Electron microscopy revealed morphological abnor-malities in both cornea and iris of the lidocaine injected eyes, different from the control group. Cytoplasmic vacuolization, phagosomes and residual bodies were observed in epithelial cells. Corneal fibroblasts contained fluid-filled vacuoles, which could be due to the influx of water into the cells as a result of corneal endothelial damage. Mitochondrial swelling and residual bodies were also seen in the cytoplasm of fibroblasts. Blood vessels in the iris contained fluid material composed of fibrin and proteinaceous material and many vacuoles showed vascular endothelial injury. CONCLUSION: Even a short period of exposure of intra-cameral lidocaine to the ocular tissues can induce histo-logical changes that may result in functional defects.