Mayumi Nagata

Analysis of surface whitening of extracted hydrophobic acrylic intraocular lenses

PURPOSE: To identify the cause of light scattering on the surface (ie, whitening) of extracted AcrySof intraocular lenses (IOLs). SETTING: Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan. METHODS: Dislocated IOLs extracted from 3 patients were stored and the IOL surfaces examined under light microscopy. The effect of whitening on visual function was evaluated by measuring light transmission with a spectrophotometer. To determine the cause of opacification, the IOLs were examined for calcium phosphate deposits using an electron probe X‐ray microanalyzer. The IOL surface, including the presence of organic deposits and evidence of hydrolysis, was also examined by Fourier‐transform infrared spectrophotometry. The IOLs were then dried, immersed again in physiological saline, and serially examined for changes in opacification. RESULTS: The optic surfaces of all IOLs had opacification due to whitening. Light transmission in the visible range of 360 to 800 nm was 4% less than that of unused IOLs. The X‐ray microanalysis showed no calcium phosphate deposits. Fourier‐transform infrared spectrophotometry of the IOL optic material showed no evidence of hydrolysis. Opacification disappeared after the IOLs were dried and then reappeared over time when the IOL was immersed again in physiologic saline. CONCLUSIONS: The findings strongly suggest that whitening of the hydrophobic acrylic IOL was due to trace water molecules that infiltrate the optic. Within the 3‐dimensional network of the polymeric lens material, the molecules are too small to form observable voids but can form water aggregates of sufficient size to scatter visible light, causing opacification (ie, whitening).

Decreased visual function due to high-level light scattering in a hydrophobic acrylic intraocular lens

PurposeTo investigate the effects of light scattering from the surface of hydrophobic acrylic intraocular lenses (IOLs) on visual function.MethodsA 67-year-old man was implanted with an IOL (MA60BM) in January 1998, but became aware of decreased visual function in May 2008. Observation with a slit lamp revealed light scattering throughout the entire optic of the IOL, which was extracted and replaced. Postoperative visual function improved at 1 month. The cause of light scattering was investigated with a focus on water permeating the IOL material. To confirm the effect of light scattering on visual function, light transmission of the extracted IOL was measured in physiological saline at 33°C, and the simulated retinal image was evaluated in a model eye.ResultsObservation of the extracted IOL showed light scattering from the optic surface layer, the main cause of which was phase-separated water within the IOL material. Light transmission in the extracted IOL was 16.3% lower than that in an unused IOL in the visible range. Moreover, the simulated retinal image was hazy compared to that of the unused IOL.ConclusionSevere surface light scattering from an IOL optic may decrease visual function.

Clinical evaluation of the transparency of hydrophobic acrylic intraocular lens optics

PURPOSE: To clinically evaluate postoperative changes in the transparency of hydrophobic acrylic intraocular lenses (IOLs). SETTING: Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan. DESIGN: Case‐control study. METHODS: Eyes having phacoemulsification were randomly assigned to have implantation of 1 of 3 hydrophobic acrylic IOL models. The IOLs were photographed at 0 degree and 90 degrees 1 week, 6 months, and 1 year after implantation using a Nidek EAS‐1000 anterior chamber analyzer in slit mode. The images were used to determine the intensity of light scattering in the surface and middle regions of the IOL optic. RESULTS: The study comprised 65 eyes of 57 patients with a mean age of 72.5 years. The rate of increase in light‐scattering intensity was similar in the middle and surface regions of the Tecnis ZA9003 aspheric IOL. The increase in light‐scattering intensity in both regions of the AF‐1 VA‐60BB spherical IOL was greater than that in the aspheric IOL at all the measurement points. The intensity of light scattering was highest and tended to increase over time in both regions of the AcrySof SA60AT spherical IOL; the rate of increase in intensity was higher in the surface region than in the middle region, and the difference was significantly greater at 6 months and 1 year than at 1 week. CONCLUSION: Our results suggest that AcrySof SA60AT and AF‐1 VA‐60BB IOLs are likely to develop glistenings over time and that the former may develop whitening. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Preventing secondary cataract and anterior capsule contraction by modification of intraocular lenses

Advances in intraocular lens (IOL) design have led to the use of lenses with improved performance including tinting, asphericity, multifocality and accommodation. To maximize the visual performance of these IOLs, postoperative complications such as secondary cataracts and anterior capsule contraction must be prevented. Various types of secondary cataracts may occur, each associated with complex biological reactions. Different design configurations, including square-edge IOLs, have been used to prevent secondary cataracts and anterior capsule contraction, but these have not been successful in sufficiently eliminating these complications. We have found that surface modification of IOL surfaces chemically improves surface quality and is also useful in preventing secondary cataracts and anterior capsule contraction. The UV/ozone treatment that we used as a surface modification method is a simple and highly effective method with no safety issues regarding materials following treatment. The combination of square-edge design and surface modification may be able to completely eliminate these postoperative complications.

Observation of whitening by cryo-focused ion beam scanning electron microscopy.

Our results indicate that ECCE conversion can achieve good results. Converting to ECCE because of a dense nucleus or the inability to achieve a continuous curvilinear capsulorhexis seems reasonable, given that in these situations one may be able to perform an ECCE similar to the way it would have been performed had it been planned. However, if vitreous loss is present, the ECCE may result in vitreous traction. It is now generally accepted that anything that could result in vitreous traction during complicated cataract surgery should be avoided. Procedures such as cellulose sponge vitrectomy and wound sweeping with a spatula are no longer considered acceptable because of the inherent traction they produce. Delivery of the nucleus during ECCE can be achieved by “pulling”manually or by “pushing” externally or internally (using balanced salt solution or an ophthalmic viscosurgical device). In the presence of vitreous loss, all these techniques may result in vitreoretinal traction (unless fragments anterior to the posterior capsule are manually removedafter a thoroughanteriorvitrectomy). Many trainees now receive little ECCE training, making the chance of a successful conversion less likely. If ECCE is unsuccessful, subsequent vitreoretinal surgery may be hampered by an enlarged wound and a cornea that may take longer to recover than if ECCE had not been attempted. In light of the above, we currently recommend that conversion to ECCE at our unit be considered only by surgeonswho are trained in ECCE surgery and vitreous loss is neither present nor likely. We hope that future studies will elucidate the role of ECCE conversion and allow surgeons to make more informed decisions.

Comparison of anterior capsule contraction between 5 foldable intraocular lens models.

PURPOSE: To compare anterior capsule contraction in cataract patients having implantation of 1 of 5 foldable intraocular lens (IOL) models and evaluate lens epithelial cell (LEC) adhesion to each model. SETTING: Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan. METHODS: This study comprised 115 patients (126 eyes) without systemic or ocular complications who had phacoemulsification with IOL implantation. The eyes were randomly assigned to receive 1 of the following IOLs: acrylic MA60BM (Alcon), SA60AT (Alcon), AR40e (Advanced Medical Optics), or YA‐60BBR (Hoya) or a silicone AQ310NV (Canon). Two weeks and 1, 3, and 6 months postoperatively, the anterior capsule opening area was measured using an anterior segment analysis system (EAS‐1000, Nidek) and the percentage of anterior capsule contraction was compared for each postoperative period and IOL. Cell adhesion to each IOL type was evaluated using LECs from albino rabbits. RESULTS: The mean age of the patients was 73.6 years ± 5.6 (SD). Eyes with the AQ310NV and AR40e IOLs had statistically significantly greater anterior capsule contraction. The rabbit study showed statistically significantly less LEC adhesion on these 2 IOL models. CONCLUSIONS: Anterior capsule contraction was significantly greater with the AQ310NV and AR40e IOLs than with the other IOLs. Results indicate that cell adhesion to the IOL is an important factor in preventing anterior capsule contraction.

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.

Efficacy of ophthalmic nonsteroidal antiinflammatory drugs in suppressing anterior capsule contraction and secondary posterior capsule opacification

PURPOSE: To evaluate the efficacy of ophthalmic nonsteroidal and steroidal antiinflammatory drugs in preventing anterior capsule contraction and secondary posterior capsule opacification (PCO) using an experimental cataract model. SETTING: Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan. METHODS: Eight‐week‐old albino rabbits weighing about 2 kg each had phacoemulsification and intraocular lens implantation. After surgery, the rabbits were divided into 3 treatment groups: diclofenac sodium ophthalmic solution, bromfenac sodium ophthalmic solution, and betamethasone ophthalmic solution. In each group, the ophthalmic solution was applied to the left eye of each rabbit twice daily; the right eye served as an untreated control. To evaluate anterior capsule contraction, the percentage of incised anterior capsule opening area was calculated on diaphanoscopic images obtained with an EAS‐1000 anterior segment analyzer. For evaluation of PCO, a tissue section was stained with hematoxylin–eosin and observed under a light microscope. The PCO was quantified on the basis of the thickness of the lens epithelial cell layer on the central subcapsular area and compared among groups. RESULTS: Fifteen albino rabbits were used in the study. Treatment with diclofenac sodium and bromfenac sodium ophthalmic solution prevented progression of anterior capsule contraction and PCO. Treatment with bromfenac ophthalmic solution did not prevent either complication. CONCLUSION: Postoperative treatment with ophthalmic nonsteroidal antiinflammatory drug solutions prevented anterior capsule contraction and PCO in rabbit eyes.