Inhibition of anterior capsule opacification and contraction by the elevated anterior rim of the intraocular lens optic.

PURPOSE: To verify the anterior capsule opacification (ACO) and contraction (ACC) of the ZCB00V intraocular lens (IOL), made of the same material as the AR40e with a high ACC rate. STUDY DESIGN: Retrospective cohort study. METHODS: We evaluated 35 patients at 1 week, 1, 3 and 6 months post phacoemulsification with either a ZCB00V (n = 35) or FY-60AD (n = 34) IOL implantation. The ACC rate was calculated using retroillumination images of the anterior segment, and the ACO was measured using anterior segment photographs and image analysis software. The contact grade between the IOL and anterior capsule was estimated from the Pentacam® images. RESULTS: The postoperative ACC rates (mean ± standard deviation) at 3 months were 1.03%±2.54% for the ZCB00V and, and 7.12%±9.47% for the FY-60AD. The ZCB00V-implanted eyes showed a significantly lower postoperative ACC at 1 week, 3 months, and 6 months (P < 0.01). On the other hand, the FY-60AD-implanted eyes had more pronounced ACO, and a significantly larger area of opacification (62.24%±21.32% vs. 16.90%±8.34%; P = 0.0005). Pentacam® analysis revealed a space between the anterior capsule and IOL surface in the ZCB00V-implanted eyes, whereas the anterior capsule firmly adhered to the IOL surface in the FY-60AD-implanted eyes. CONCLUSION: The ACC and ACO were significantly lower in eyes with ZCB00V IOLs compared to those with the FY-60AD. The anterior segment image analysis revealed that the elevated anterior rim of the ZCB00V IOL prevented adhesion between the anterior capsule and IOL optic surface, suggesting an open capsule effect.

Effects of decentration and tilt on the optical performance of 6 aspheric intraocular lens designs in a model eye.

PURPOSE: To compare the effect of decentration and tilt on the optical performance of 6 aspheric intraocular lens (IOL) designs in a model eye. SETTING: Department of Ophthalmology, Graduate School of Medicine, Dokkyo Medical University, Tochigi, Japan. DESIGN: Experimental study. METHODS: In theoretical simulations, the amount of spherical aberration in the IOL was varied to produce residual ocular spherical aberration (range -0.15 to 0.30 µm) at a 6.0 mm entrance pupil. Wavefront aberration analyses were performed with the ZEMAX optical design program (version August 20, 2014) to obtain the ocular root-mean-square values of astigmatism, coma, trefoil, and higher-order aberrations (HOAs) when the IOL was centered on the insertion position and misaligned at a 4.0 mm entrance pupil. The retinal visual images were calculated using the same conditions. Six 20.0 diopter (D) aspheric IOLs and one 20.0 D spherical IOL were used for the experimental studies. Each IOL was inserted in the model eye. The actual alignments were measured using a Scheimpflug camera (EAS-1000). The wavefront aberrations and visual images were gauged using a wavefront analyzer (KR-1W) at several IOL alignments. RESULTS: Intraocular lens decentration and tilt increased wavefront aberrations and degraded optical performance. Astigmatism, coma, and HOAs generated by misaligned IOLs were related to the amount of spherical aberration correction of the IOLs. The extent of spherical aberration remained unchanged by the amount of misalignment. Experimental model eye results showed trends similar to theoretical results. CONCLUSIONS: The spherical aberration correction amount in the aspheric IOL design was critical for the astigmatism, coma, and HOAs generated by the IOL misalignment. Additional spherical aberration corrections led to a more sensitive optical performance degradation resulting from IOL misalignment.

Open-capsule intraocular lens to prevent posterior capsule opacification.

PURPOSE: To develop a single-piece open-capsule intraocular lens (IOL) that can be inserted through a small incision and that prevents posterior capsule opacification (PCO) by expanding the capsule and circulating aqueous humor into the capsular bag. SETTING: Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan. DESIGN: Experimental study. METHOD: Using the same hydrophobic acrylic material as the NY-60 IOL, a prototype open-capsule IOL was constructed. The IOL has a single optic and 2 haptics, with a 2.8 mm high spacer and holes through which aqueous humor circulates into the capsular bag by separating the anterior capsule from the posterior capsule and expanding the capsule. The open-capsule IOL or NY-60 (as a control group) was inserted in rabbit eyes. Posterior capsule opacification development was evaluated by measuring the thickness of the cell layer at the center of the posterior capsule on histopathologic specimens and statistically comparing the thickness between the open-capsule IOL group and control group. RESULTS: The open-capsule IOL could be inserted through a 3.2 mm corneal incision using a D cartridge. The mean thickness of the cell layer at the center of the posterior capsule was 4.78 µm ± 2.61 (SD) in the open-capsule IOL group and 101.14 ± 25.19 µm in the control group and was significantly smaller in the open-capsule IOL group. CONCLUSION: The prototype single-piece IOL could be implanted through a small incision and prevented PCO by expanding the lens capsule and circulating aqueous humor into the capsular bag.

Reduced aqueous humour ascorbic-acid concentration in women with smaller anterior chamber depth.

Short anterior chamber depth (ACD) is considered a risk factor of endothelial-cell loss after phacoemulsification. However, whether it is an independent risk factor or not remains controversial. We investigated the relationship between ascorbic acid (AA) concentrations in the aqueous humour (AqH) and ACD. We analysed 165 AqH samples of 97 patients (42 men and 55 women) who underwent small incision cataract surgery. AqH and plasma AA concentrations were measured using a high-performance liquid chromatography - electrochemical detection method. Patient characteristics were compared between and within the sexes. As a result, age and ACD were significantly correlated with AqH AA concentrations (r = -0.206, P = 0.045; r = 0.339, P < 0.001) only in women. Moreover, plasma AA concentrations were significantly correlated with AqH AA concentrations (r = 0.420, P < 0.001; r = 0.316, P = 0.002) both in men and women. After adjusting for confounding factors (age and plasma AA concentrations), ACD was significantly and positively correlated with AqH AA concentrations (partial.r = 0.275, P = 0.009) only in women. In conclusion, AqH AA concentrations were reduced in women with smaller ACD. This may suggest that women with short ACD could be more susceptible to oxidative damage.

Intrascleral fixation of intraocular lens haptics: histological advantages in a comparison with scleral suture fixation in rabbits.

PURPOSE: To disclose histological advantages of intrascleral fixation of intraocular lens haptics, in comparison with scleral suture fixation, in a study with rabbits. METHODS: Ten white rabbits, 10 weeks of age, were used in this experimental histopathological study. After unilateral lensectomy and anterior vitrectomy, an intraocular lens haptic was inserted into one eye of each rabbit. Intrascleral fixation was performed in five rabbits, whereas scleral suture fixation was performed in the others. At postoperative 1 week, the globe was enucleated in two rabbits in each group; at postoperative 8 weeks, the globe was enucleated in the remaining three rabbits in each group. Sections of the sclera around haptics and sutures were evaluated with haematoxylin and eosin and immunohistochemical staining methods. We assessed severity of inflammation on histopathological photos, taken near the haptic or suture in the sclera, by counting white blood cells. The Mann-Whitney U test was performed to analyse differences in the severity of inflammation between the groups. RESULTS: Samples in the intrascleral fixation group demonstrated reduced irregularity of collagen fibres; reduced infiltration of fibroblasts, giant cells, lymphocytes, neovascular cells, neutrophils and eosinophils and weaker staining for fibronectin (indicating tissue repair) and heat shock protein 70 (indicating cell damage). In addition, reduced white blood cell infiltration was observed in the intrascleral fixation samples at 8 weeks in both shallow sclera (p = 0.001) and deep sclera (p = 0.002). CONCLUSIONS: Histological analysis showed that intrascleral fixation caused fewer inflammatory changes than scleral suture fixation, with reduced fibroblast migration and production of cytotoxic factors.

Influence of intraocular lens implantation on anterior capsule contraction and posterior capsule opacification.

PURPOSE: To evaluate whether and how intraocular lens (IOL) implantation influences the development of anterior capsule contraction and posterior capsule opacification (PCO). SETTING: Department of Ophthalmology, Dokkyo Medical University, Mibu, Tochigi, Japan. DESIGN: Experimental study. METHODS: Phacoemulsification was performed in 8-week-old white rabbits. A hydrophobic acrylate IOL (12.5 mm) (YA-60BBR) was implanted in 1 eye and no IOL was implanted in the fellow eye. Slitlamp microscopy and anterior segment analysis were performed to evaluate anterior capsule contraction after the surgery. Four weeks postoperatively, sections of the eyes were made, and the thickness of the proliferated lens epithelial cell (LEC) layer at the posterior capsule was measured to assess the PCO. In addition, LECs from white rabbits were cultured in medium containing 50% aqueous humor or in medium containing 50% saline to determine the influence of the aqueous humor on LECs and to compare the degree of LEC proliferation. RESULTS: Starting 2 weeks after surgery, anterior capsule contraction progressed more significantly in the IOL group than in the group without IOLs. Four weeks postoperatively, LEC thickness at the posterior capsule was significantly less in the group without IOLs than in the IOL group. In the culture study, LEC proliferation was more inhibited in the aqueous humor group than in the saline group. CONCLUSIONS: Progression of anterior capsule contraction and PCO is less likely in aphakic eyes than in IOL-implanted eyes. The mechanism of prevention may involve aqueous humor-induced inhibition of LEC proliferation.

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.

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).

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.

Sequential or superexchange mechanism in bridged electron transfer distinguished by dynamics at a bridging molecule.

Two kinds of mechanisms are well known for electron transfer (ET) in the system DMA where a donor D and an acceptor A are fixed in a close distance by a bridging molecule M. When the free energy DeltaG(m) of the intermediate state |m of DM(-)A is much higher than the thermal energy k(B)T above the initial state of D(-)MA, the ET occurs unistep from D to A by the superexchange (SX) mechanism, passing |m as a quantum-mechanical virtual state. However, when DeltaG(m) becomes not much higher than k(B)T, the ordinary sequential (OS) ET may manifest itself, where the second ET from |m to the final state of DMA(-) takes place after thermalization of phonons in |m. Recently, much interest has been aroused in how the SX mechanism switches to the OS one as DeltaG(m) is lowered. This subject has often been described conventionally by summation of the rate constant for the SX mechanism and that for the OS one. However, such convention cannot be justified, since these mechanisms are realized in mutually opposite limits concerned with dynamics in mediation of ET by a bridging molecule, hence they cannot both be realized simultaneously in a single system. An observation of such a bridged ET by Paulson, Miller, Gan and Closs (J. Am. Chem. Soc. 2005, 127, 4860) provides a good example of this feature. Describing their observation in a unified framework for the ET, it is shown that the switch occurs at DeltaG(m) congruent with-0.5 eV, which is much lower than 0.3 eV reported by them, where the hot-sequential ET reveals itself, taking place during thermalization of phonons in |m.

Photoprotective effect of yellow-tinted intraocular lenses.

PURPOSE: The aim of this study was to experimentally investigate changes in visible light-induced photo-oxidation and to evaluate the inhibitory effect of various acrylic tinted intraocular lenses (IOLs) on photooxidation. METHODS: Three types of nontinted (VA-60BB, HOYA; SA60AT, Alcon; AU-6, Menicon) and tinted (YA-60BB, HOYA; SN60AT, Alcon; AN-6, Menicon) IOLs were used. In the first experiment, we investigated oxidation related to ultraviolet rays by using a mixed solution of reduced glutathione, nicotinamide adenine dinucleotide phosphate (NADPH), and glutathione reductase. The mixed glutathione solution was irradiated for 30, 60, or 90 min with direct artificial sunlight or artificial sunlight that had been passed through various IOLs. Oxidation was detected at 340 nm. In the second experiment, human retinal pigment epithelium (RPE) cells were prepared and cultured in a 96-well dish until confluent. After light exposure for 30 min or 48 h, lactate dehydrogenase (LDH) levels of the culture supernatant were measured to assess the amount of cell damage. RESULTS: Visible light-induced glutathione oxidation progressed over time. Intraocular lenses inhibited photooxidation, with the inhibitory effect shown to increase when tinted IOLs were used. LDH levels in RPE cells increased as a result of exposure to visible light. There was a higher increase in LDH with nontinted than with tinted IOLs. CONCLUSION: Visible light causes photooxidation, which damages intraocular tissue in vitro. These results suggest that tinted IOLs effectively inhibit tissue damage from visible light.

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.

[Effects of calcium on lens epithelial cells in rabbits].

PURPOSE: The action of lens epithelial cells (LECs) is important for cataract and posterior subcapsular cataract after cataract surgery. In this study, we analyzed the effects of calcium on the characteristics of LECs. METHODS: The LECs were collected using albino rabbits and incubated in minimum essential medium [MEM, Introgen Corp. (12% fetal bovine serum: FBS)] (37 degrees C, 5 % CO2) for a week to induce their proliferation. Cell culture dishes (35 mm) were prepared and 7 mm cylindrical pipes were placed in them. After that, around 10,000 cultured LECs were placed in the pipes and incubated. After 2 hours incubation, the pipes were removed and various doses of MEM (0, 2, 10 and 20 mM) replaced the calcium. Proliferation and shapes of LECs were observed using a confocal microscope and immunohistological analysis [alpha-smooth muscle actin (alpha-SMA) and bromodeoxyuridine (BrdU)]. The LECs were incubated with collagen gel and different calcium doses (0, 2, 10 and 20 mM) of MEM to calculate the contraction rate. RESULTS: It was observed that the LECs changed to fibroblast-like cells at high doses of calcium using a confocal microscope. Histological studies showed that the BrdU positive cells were increased by using 10 and 20 mM calcium MEM, but the positive cells were decreased by using 0 and 2 mM calcium MEM. Increase of alpha-SMA stained cells was recognized when using 0, 10 and 20 mM calcium MEM. The contraction rate of collagen gel was increased by using the 10 and 20 mM calcium MEM. CONCLUSION: The changes of calcium concentration might be an important factor for the development of cataract, posterior subcapsular opacification, and contraction of the lens capsule after cataract surgery.

[Protective effect on the corneal endothelium and remaining effect at the anterior chamber for three different kinds of viscoelastic devices].

PURPOSE: The present study was performed to evaluate the corneal endothelium protection and anterior chamber stagnation abilities of three different types of viscoelastic substances (Healon, Viscoat, HealonV). METHODS: Viscoelastic substances were selected at random for 120 eyes with cataracts, and the postoperative reduction rates of the corneal endothelium cells were compared. The residual viscoelastic substances after filling of the anterior chamber of pig eyes and aspiration with a handpiece were measured by an anterior eye segment image analysis system. The same procedures were performed in rabbit eyes and the residual levels of viscoelastic substances on the corneal endothelium were photographed histologically. RESULTS: The reduction rate of endothelium corneal cells tended to decrease with Viscoat three months after surgery. The results obtained with the anterior eye segment image analysis system showed that the residual level in the anterior chamber was higher with Healon. Histological analyses demonstrated residual Viscoat at the center of the corneal endothelium after perfusion. CONCLUSION: HealonV was superior in terms of spatial retention and Viscoat had corneal endothelium protection potential.

Histologic and histochemical changes in rabbit cornea produced by an orthokeratology lens.

PURPOSE: To report the histologic and histochemical properties of rabbit cornea after insertion of an orthokeratology lens. METHODS: An orthokeratology lens was placed on the left corneas of rabbits for 8 hours daily, and their eyes were enucleated after 7, 14, 21, and 28 days and examined histologically and histochemically. The right eyes were used as controls. RESULTS: After 7-14 days, hematoxylin and eosin staining of the cornea revealed that the epithelial layer was slightly thinner in the central area and thicker in the intermediate area, but its thickness gradually became normal toward the limbus. Periodic acid-Schiff staining showed no abnormal distribution of glycogen granules or glycogen producing cells. 5-bromo-2-deoxyuridine staining revealed more mitoses in the central area than in the intermediate area. Histochemical staining showed lactic dehydrogenase activity in the central area of the lens, whereas alkaline phosphatase activity and beta-glucuronidase activity were slightly increased in the intermediate area. There were no other clearly abnormal findings. CONCLUSIONS: The thickness of the corneal epithelium showed topographical variation consistent with the effect of orthokeratology. The result of histochemical studies suggested that there were no marked alterations in epithelial function.