[Optimization of phacoemulsification technique for Morgagnian cataract]. / Optimizatsiya tekhnologii fakoemul'sifikatsii morganievoi katarakty.

PURPOSE: This study was conducted to develop a new optimized phacoemulsification technique for Morgagnian cataract taking into account the anatomical and topographic parameters of the lens nucleus. MATERIAL AND METHODS: A working classification of Morgagnian cataract was developed based on the size of the nucleus: if the edge of the nucleus is visualized at the upper edge of the pupil or between the upper edge and the middle of the pupil, it was classified as an initial stage of Morgagnian cataract with a large nucleus; if the upper edge of the nucleus is visualized in the middle of the pupil and below, it was classified as an advanced stage of Morgagnian cataract with a small nucleus. The first group included six patients who underwent surgery using the scaffold technique with removal of the whole small nucleus into the anterior chamber. The second group included 11 patients who underwent surgery using the scaffold technique with removal of the last fragment of the nucleus into the anterior chamber. RESULTS: The use of the scaffold technique with removal of the nucleus into the anterior chamber helped reduce the number of intraoperative complications to 16.7% in the first group, compared to 27.3% in the second group, and the percentage of endothelial cell loss to 10.1% in the first group, compared to 10.7% in the second group. CONCLUSIONS: The anatomical and topographic features of the lens and the anterior segment of the eye in Morgagnian cataract with a small nucleus allow for preliminary implantation of an intraocular lens into the capsular bag to protect the posterior capsule during phacoemulsification of the nucleus with minimal mechanical, hydrodynamic and acoustic damage to the surrounding structures of the eye.

[Rotational technique for emulsification of soft lens nucleus]. / Rotatsionnaya metodika emul'sifikatsii myagkogo yadra khrustalika.

Effective and atraumatic removal of a soft lens nucleus requires different surgical techniques compared to phacoemulsification of a dense nucleus. PURPOSE: This study was conducted to develop a non-ultrasound technique for emulsification of a soft lens nucleus. MATERIAL AND METHODS: Fifty-seven patients (57 eyes) underwent surgery. In 23 cases, early or immature cataracts were detected, and in 34 cases, lens removal was performed for refractive purposes in high myopia and complex myopic astigmatism. Phacoemulsifier Centurion Vision System (Alcon Laboratories, Inc., USA) was used for the surgery. Aspiration of soft lens nucleus was done using a rotational technique. The following aspects were evaluated in the course of the surgery: the volume of the required irrigation solution, and the frequency needing to involve ultrasound for complete emulsification of the lens nucleus. Intraoperative and postoperative complications were also assessed. RESULTS: The surgery was uneventful in all cases. There were no violations of the integrity of capsulorhexis edge. The need for short pulses of minimal power ultrasound during the removal of the soft lens using this technique arose only in 11 (19.3%) cases. The effective ultrasound time was less than 1 second. The required volume of irrigation solution was 33.0 (24.0; 43.0) ml, which does not differ significantly from that in ultrasonic phacoemulsification. CONCLUSIONS: The use of modern phacoemulsifiers providing a high vacuum level allows successful removal of a soft lens without using ultrasound, which prevents its negative impact on the ocular tissues. The use of adequate surgical techniques, including the optimal direction of rotation of the lens nucleus in the rotational technique, improves the efficiency of soft lens nucleus removal.

[Influence of the pattern of femtosecond laser-assisted lens nucleus fragmentation on the energy and hydrodynamic parameters of phacoemulsification]. / Vliyanie patterna fragmentatsii yadra khrustalika femtosekundnym lazerom na energeticheskie i gidrodinamicheskie parametry fakoemul'sifikatsii.

The influence of various patterns of preliminary femtosecond laser-assisted fragmentation of the lens nucleus on the energy and hydrodynamic parameters of phacoemulsification remains insufficiently studied. PURPOSE: This study evaluates the influence of various patterns of preliminary femtosecond laser-assisted fragmentation of the lens nucleus on the energy, hydrodynamic parameters of phacoemulsification, and the degree of corneal endothelial cell loss. MATERIAL AND METHODS: Hybrid phacoemulsification was performed in 336 patients (336 eyes) with grade IV immature cataract according to the Buratto classification in three age-matched groups. Group 1 included 103 patients (103 eyes) who underwent hybrid phacoemulsification with preliminary femtosecond laser-assisted fragmentation of the nucleus with a «pizza¼ pattern (division of the nucleus with 10 radial cuts). Group 2 included 112 patients (112 eyes) who underwent femtosecond laser-assisted fragmentation of the nucleus with a «cylinders¼ pattern (division of the nucleus with 8 radial cuts in combination with 5 circular cuts). Group 3 included 121 patients (121 eyes) who underwent femtosecond laser-assisted fragmentation of the nucleus with a «grid¼ pattern (division of the nucleus with 8 radial cuts in combination with multiple mutually perpendicular cuts in the central zone in the form of a grid with a 0.5 mm cell). Effective ultrasound time and the volume of irrigation solution for emulsification of the lens nucleus fragments were determined during the operation. The loss of corneal endothelial cells was assessed 3 months after surgery. RESULTS: The minimum effective ultrasound time was noted after using the "grid" pattern - 4.05 (2.88; 4.74) s, which was significantly less than with the "cylinders" pattern - 4.97 (3.78; 5.88) s and the "pizza" pattern - 6.15 (4.52; 7.75) s (p<0.05). The effective ultrasound time when using the "cylinders" pattern was significantly less than with the "pizza" pattern (p<0.05). The volume of irrigation solution used for emulsification of the lens nucleus fragments was significantly less in the "grid" pattern - 41.5 (33.5; 49.5) ml compared to the "cylinders" patterns 58.5 (51.0; 66.0), p<0.05 and "pizza" pattern 75.0 (66.0; 83.5), p<0.01. The volume of irrigation solution when using the "cylinders" pattern was significantly less than when using the "pizza" pattern (p<0.05). The loss of corneal endothelial cells after using the "grid" pattern was 8.82 (7.59; 9.87)%, which was significantly less than after the "cylinders" patterns - 9.97 (8.81; 10.83)%, p<0.05 and "pizza" - 11.70 (10.62; 12.97)%, p<0.05. At the same time, the loss of endothelial cells after using the "cylinders" pattern was significantly less than after the "pizza" pattern (p<0.05). CONCLUSIONS: The choice of the optimal pattern of preliminary femtosecond laser-assisted fragmentation of the lens nucleus provides a significant decrease in the energy and hydrodynamic parameters of phacoemulsification and, accordingly, the loss of corneal endothelial cells.

[Surgical technique for aspiration of soft lens nucleus with preoperative femtosecond laser-assisted fragmentation]. / Khirurgicheskaya tekhnika aspiratsii myagkogo yadra khrustalika s predvaritel'noi femtolazernoi fragmentatsiei.

Fragmentation and aspiration of soft cataracts require different surgical techniques and approaches compared to the removal of dense nuclei, including when using a femtosecond laser. PURPOSE: This study was conducted to develop a non-ultrasound technique for aspiration of a soft lens nucleus after its preliminary femtosecond laser-assisted fragmentation. MATERIAL AND METHODS: The study included 63 patients (63 eyes) aged 23 to 40 years who underwent surgery. In 27 cases, early or immature cataract was observed, and in 36 cases, cataract removal was performed for refractive purposes in high myopia and complex myopic astigmatism. The VICTUS femtosecond laser surgical system (Technolas Perfect Vision GmbH, Germany) was used for preliminary fragmentation of the lens nucleus. Surgeries were performed using the Centurion Vision System phacoemulsifier (Alcon Laboratories, Inc., USA). The volume of the required irrigation solution was evaluated during the surgery. Intraoperative and postoperative complications were assessed. RESULTS: The surgery was performed without complications in all cases. Capsulorhexis edge was completely preserved along its entire circumference. The study showed the fundamental possibility of aspirating a cataract with a nucleus of grade I-II density without low-frequency ultrasound after preliminary femtosecond laser-assisted fragmentation of the nucleus with a "grid" pattern, which ensures minimal fragment size in the central zone of the nucleus. The volume of irrigation solution required for aspiration of the nucleus was 36.0 (27.0; 44.0) ml, which does not significantly differ from the volume of solution during ultrasound phacoemulsification of a nucleus of such density. CONCLUSIONS: Femtosecond laser-assisted fragmentation of the lens nucleus with a "grid" pattern and phacoemulsifier systems with a high vacuum level allow effective aspiration of a soft lens without using low-frequency ultrasound.

Spontaneous Dislocation of the Lens Nucleus Into the Anterior Chamber Observed in a Patient With Overmature Senile Cataract.

Overmature cataract refers to the advanced stage of cataract where timely surgical intervention is not performed, leading to further progression characterized by decreased water content in the lens, degradation of fibers, and liquefaction within its structure, which can cause a reduction in volume, wrinkling of the capsule, as well as calcification or cholesterol crystallization on its surface. In addition, it may result in deepening of the anterior chamber. If left promptly untreated, these complications may result in visual impairment or even blindness. The occurrence of spontaneous complete dislocation of the lens nucleus into the anterior chamber in overmature cataracts is extremely uncommon. The authors present a case study involving a 74-year-old female patient who was diagnosed with complete dislocation of the lens nucleus in an overmature senile cataract without any apparent ocular injury or any relevant medical records. After undergoing cataract removal combined with anterior vitrectomy, the patient experienced relief from eye discomfort and expressed satisfaction with the surgical outcome; however, her visual acuity did not show significant improvement.

Intraoperative quantitative crystalline lens nuclear opacities analysis based on crystalline lenSx platform.

PURPOSE: The main objective is to quantify the lens nuclear opacity using spectral-domain optical coherence tomography (SD-OCT) and to evaluate its association with Lens Opacities Classification System III (LOCS-III) system, lens thickness (LT), and surgical parameters. The secondary objective is to assess the diagnostic model performance for hard nuclear cataract. METHODS: This study included 70 eyes of 57 adults with cataract, with 49 (70%) and 21 (30%) in training and validation cohort, respectively. Correlations of the average nuclear density (AND) /maximum nuclear density (MND) with LOCS-III scores, LT, and surgical parameters were analyzed. Univariate and multivariate logistic regression analysis, receiver operating characteristic curves and calibration curves were performed for the diagnostic of hard nuclear cataract. RESULTS: The pre-operative uncorrected distance visual acuity (UDVA), intraocular pressure (IOP), mean axial length (AL), and LT were 1.20 ± 0.47 log MAR, 15.50 ± 2.87 mmHg, 27.34 ± 3.77 mm and 4.32 ± 0.45 mm, respectively. The average nuclear opalescence (NO) and nuclear colour (NC) scores were 3.61 ± 0.94 and 3.50 ± 0.91 (ranging from 1.00 to 6.90), respectively. The average AND and MND were 137.94 ± 17.01 and 230.01 ± 8.91, respectively. NC and NO scores both significantly correlated with the AND (rNC = 0.733, p = 0.000; rNO = 0.755, p = 0.000) and MND (rNC = 0.643, p = 0.000; rNO = 0.634, p = 0.000). In the training cohort, the area under the curve (AUC) of the model was 0.769 (P < 0.001, 95%CI 0.620-0.919), which had a good degree of differentiation (Fig. 2a). The calibration curve showed good agreement between predicted and actual probability. CONCLUSION: The nuclear density measurement on SD-OCT images can serve as an objective and reliable indicator for quantifying nuclear density.

First in-human clinical performance of a new non-cavitating handheld lensectomy system in 665 consecutive cataract surgeries.

PURPOSE: To investigate the intraoperative performance and lens fragmentation efficacy of a non-cavitating handheld lensectomy system in mild, moderate, and severe cataract. SETTING: Ambulatory surgical centers. DESIGN: Retrospective consecutive case series. METHODS: 665 consecutive eyes underwent cataract surgery by 12 surgeons using a new handheld non-cavitating lensectomy system for nuclear fragmentations and extraction. Intraoperative measurements included surgical time, miLOOP pretreatment, and irrigation fluid use. RESULTS: Of the 665 eyes, 38 (6%), 468 (70%), 126 (19%), and 33 (5%) were of grade 1, 2, 3, and 4 nuclear densities, respectively, as graded by the surgeon intraoperatively. Successful nuclear fragmentation, lens extraction, and cortical removal were achieved in all eyes. Total nucleus fragmentation and extraction times were 70.1 seconds, 100.3 seconds, 132.6 seconds, and 287.9 seconds for grades 1, 2, 3, and 4, respectively ( P < .001). In addition, irrigation and aspiration cortical removal times were 64.1 seconds, 51.1 seconds, 48.5 seconds, and 59.0 seconds, respectively ( P = .14). There was a low rate of capsular tear (3 cases in 665 surgeries, 0.45%) and no other emergent adverse events. CONCLUSIONS: The miCOR handheld non-cavitating lensectomy system demonstrated nuclear fragmentation and extraction in the absence of intraocular cavitation across all grades of nuclear densities.

Viscoelastic properties of porcine lenses using optical coherence elastography and inverse finite element analysis.

The mechanical properties of the crystalline lens are crucial in determining the changes in lens shape that occur during the accommodation process and are also a major factor in the development of the two most prevalent age-related diseases of the lens, presbyopia and cataracts. However, a comprehensive understanding of these properties is currently lacking. Previous methods for characterizing the mechanical properties of the lens have been limited by the amount of data that could be collected during each test and the lack of complex material modeling. These limitations were mainly caused by the lack of imaging techniques that can provide data for the entire crystalline lens and the need for more complex models to describe the non-linear behavior of the lens. To address these issues, we characterized the mechanical properties of 13 porcine lenses during an ex vivo micro-controlled-displacement compression experiment using optical coherence elastography (OCE) and inverse finite element analysis (iFEA). OCE allowed us to quantify the internal strain distribution of the lens and differentiate between the different parts of the lens, while iFEA enabled us to implement an advanced material model to characterize the viscoelasticity of the lens nucleus and the relative stiffness gradient in the lens. Our findings revealed a pronounced and rapid viscoelastic behavior in the lens nucleus (g1 = 0.39 ± 0.13, τ1 = 5.01 ± 2.31 s) and identified the lens nucleus as the stiffest region, with a stiffness 4.42 ± 1.20 times greater than the anterior cortex and 3.47 ± 0.82 times greater than the posterior cortex. However, due to the complex nature of lens properties, it may be necessary to employ multiple tests simultaneously for a more comprehensive understanding of the crystalline lens.

Real-time corneal thickness changes during phacoemulsification cataract surgery.

PURPOSE: To observe the changes in corneal thickness during phacoemulsification cataract surgery and to analyze the influencing factors. METHODS: One hundred two patients (102 eyes) with cataracts undergoing phacoemulsification cataract surgery at Shandong Eye Hospital between July and October 2021 were included. Intraoperative OCT was applied to capture real-time images preoperatively, before and after ultrasonic emulsification, at the end of irrigation aspiration and the end of surgery. Then, the corneal thickness at the above time points was measured using Photoshop software. RESULTS: The corneal thickness of 102 cataract patients was 511.79 ± 31.46 µm before operation and 512.71 ± 31.51 µm at the beginning of phacoemulsification, which increased by 0.91 ± 1.48 µm (0.2%). At the end of ultrasonic emulsification, the corneal thickness was 521.58 ± 32.75 µm and 8.87 ± 8.71 µm (1.7%) thicker than that before the procedure. After irrigation aspiration, the corneal thickness reached 528.09 ± 33.87 µm, which increased by 6.52 ± 6.38 µm (1.3%) compared with that of the previous step. At the end of the operation, the corneal thickness was 539.19 ± 33.88 µm, 11.09 ± 10.92 µm, and 27.37 ± 13.64 µm thicker than that of the previous step and the preoperative thickness, respectively, with an overall increase of 5.3%. The differences were statistically significant at all time points (all P < 0.001). Correlation analysis showed that postoperative corneal thickness changes were correlated with age, cataract lens nuclear grade, actual phacoemulsification time (APT), effective phacoemulsification time (EPT), average phacoemulsification energy (APE), total surgery time (TST), cell density (CD), maximum cell area (MAX), and cell area standard deviation (SD) (all P < 0.05), while the changes in thickness were not correlated with gender, cell area coefficient of variation (CV), percentage of hexagonal cells (6A), average cell area (AVE), or minimum cell area (MIN) (all P > 0.05). CONCLUSIONS: During phacoemulsification cataract surgery, corneal thickness gradually increases in real time with the increase of perfusion pressure and intraocular manipulation time. The real-time magnitude of intraoperative corneal thickness change is closely related to lens nucleus hardness, corneal endothelial cell density, ultrasound energy, and time for emulsification.

Deslocamento espontâneo do núcleo do cristalino para câmara anterior / Spontaneous displacement of the lens nucleus into the anterior chamber

RESUMO Ao longo da vida, o cristalino produz novas fibras dispostas de forma concêntrica, que aumentam seu diâmetro anteroposterior e peso, tornando seu núcleo mais compacto e endurecido. A catarata hipermadura é uma forma de progressão avançada dessa proliferação de fibras, que pode desencadear uma variedade de complicações. A ruptura espontânea da cápsula anterior do cristalino, evoluindo com deslocamento anterior do núcleo, é uma complicação rara e com poucos casos publicados na literatura. Descrevemos o caso de uma paciente do sexo feminino, 68 anos, que apresentou ruptura espontânea da cápsula anterior do cristalino com deslocamento anterior do núcleo em olho esquerdo sem histórico de trauma ocular. A paciente foi submetida à facoemulsificação do cristalino e ao controle da pressão intraocular, evoluindo com melhora do quadro clínico.

ABSTRACT Throughout life, the lens produces new fibers arranged concentrically, which increase its anteroposterior diameter and weight, making its nucleus more compact and hardened. Hypermature cataract is an advanced stage of this fiber proliferation, which can trigger a variety of complications. Spontaneous rupture of the anterior lens capsule evolving with anterior displacement of the nucleus is a rare complication, with few cases published in the literature. We describe the case of a 68-year-old female patient, who presented spontaneous rupture of the anterior lens capsule with anterior displacement of the nucleus in the left eye, without a history of ocular trauma. The patient underwent phacoemulsification and clinical control of intraocular pressure, improving her condition.

Effect of Timing of Pars Plana Vitrectomy on Visual Outcome in Cases of Nucleus Drop during Phacoemulsification.

PURPOSE: The purpose of the study was to study the relationship between the timing of pars plana vitrectomy (PPV) with corrected distance visual acuity (CDVA) in cases of nucleus drop during phacoemulsification. METHODS: This retrospective analysis included 83 patients, who underwent PPV for nucleus or nuclear fragment drop from July 2017 to November 2019. Timing of PPV (≤2 weeks and >2 weeks) after the primary cataract surgery was noted. The primary endpoint was CDVA at 1 month, which was compared with the time of PPV. Visual outcome was assessed as good if CDVA was better than or equal to 20/40 and poor if CDVA was worse than 20/40. Mode of management along with type of secondary intraocular lens (IOL) implanted was also evaluated. RESULTS: Out of the 83 cases (55 males and 28 females) in which vitrectomy for nucleus drop was performed, 36 cases were operated within 2 weeks and 47 were operated between 2 weeks and 1 month. In cases which were operated within 2 weeks, CDVA of 20/20-20/40 was achieved in 33 cases. For those who were operated on after 2 weeks, CDVA of 20/20-20/40 was achieved in 43 cases. The difference in visual outcome in both the groups was statistically nonsignificant (Fisher's exact t-test, P = 0.97). In 64 (77%) cases, adequate sulcus was present, in which foldable 3-piece IOL was placed in 29 (35%) cases. CONCLUSION: Timing of intervention has no bearing on the final visual outcome after vitrectomy in cases of nucleus drop during phacoemulsification. The continuity of the capsulorrhexis and the availability of capsular support determines the type of placement of the lens. A foldable lens can be placed in the sulcus if continuous capsulorrhexis is present.

EphA2 Affects Development of the Eye Lens Nucleus and the Gradient of Refractive Index.

Purpose: Our studies in mouse eye lenses demonstrate that ephrin-A5 and EphA2 are needed for normal epithelial cells and lens transparency. We sought to determine whether EphA2 and ephrin-A5 are important for lens morphometrics, nucleus formation, and refractive index. Methods: We performed tissue morphometric measurements, electron microscopy, Western blots, and interferometric measurements using an X-ray synchrotron beam source to measure the gradient of refractive index (GRIN) to compare mouse lenses with genetic disruption of EphA2 or ephrin-A5. Results: Morphometric analysis revealed that although there is no change in the overall lens volume, there is a change in lens shape in both EphA2-/- lenses and ephrin-A5-/- lenses. Surprisingly, EphA2-/- lenses had small and soft lens nuclei different from hard lens nuclei of control lenses. SEM images revealed changes in cell morphology of EphA2-/- fiber cells close to the center of the lens. Inner EphA2-/- lens fibers had more pronounced tongue-and-groove interdigitations and formed globular membrane morphology only in the deepest layers of the lens nucleus. We did not observe nuclear defects in ephrin-A5-/- lenses. There was an overall decrease in magnitude of refractive index across EphA2-/- lenses, which is most pronounced in the nucleus. Conclusions: This work reveals that Eph-ephrin signaling plays a role in fiber cell maturation, nuclear compaction, and lens shape. Loss of EphA2 disrupts the nuclear compaction resulting in a small lens nucleus. Our data suggest that Eph-ephrin signaling may be required for fiber cell membrane reorganization and compaction and for establishing a normal GRIN.

Evaluation of efficacy of new lens nucleus fragmenting forceps in cataract surgery / Avaliação da eficácia de uma nova pinça fragmentadora de núcleo do cristalino para cirurgia de catarata

ABSTRACT Objective: To evaluate the efficacy of low-cost nucleus fragmenting forceps designed to reduce the use of ultrasound during phacoemulsification. Methods: A total of 60 pig eyes enucleated 10 hours before were placed in the microwave oven, at maximum power for 10 seconds, to form cataracts with hardness comparable to a grade IV nucleus in the Lens Opacities Classification System III. Cataract extraction was performed using the Centurion® phacoemulsifier (Alcon Laboratories, Geneve, Switzerland) and Leica M620 microscope. All eyes were submitted to the pre-chop technique dividing the nucleus into four parts. After the pre-chop, the quadrants in 30 eyes were phacoemulsified with the torsional mode and were fragmented in the remaining 30 eyes after the pre-chop was with the fragmentation forceps before torsional mode phacoemulsification. The device was calibrated for all eyes by applying the following parameters: 40% linear torsional phacoemulsification; intraocular pressure of 65 mmHg; the linear vacuum of 600 mmHg; aspiration flow of 40 ccs/minute. After each procedure, the following was recorded: cumulative dissipated energy; equivalent average torsional amplitude; equivalent average ultrasonic power; estimated aspirated fluid; ultrasound total time; and total aspiration time. Statistical analysis was performed using the Kruskal-Wallis test and the IBM Statistical Package for Social Sciences. The p-value <0.05 was considered statistically significant. Results: There was a statistically significant reduction favoring the use of the nucleus fragmenting forceps in all parameters, except for the average torsional amplitude. Conclusion: The use of the nucleus fragmenting forceps contributed to improving the efficacy of torsional phacoemulsification in enucleated pig eyes.

RESUMO Objetivo: Avaliar a eficácia de uma pinça fragmentadora de núcleo, de baixo custo, desenvolvida para reduzir o uso de ultrassom durante a emulsificação do núcleo. Métodos: Sessenta olhos de porco com 10 horas de enucleação foram colocados no forno de microondas, em potência máxima por 10 segundos, para a formação de catarata com dureza comparável à de um núcleo grau IV na Lens Opacities Classification System III. A extração da catarata foi realizada com o facoemulsificador Centurion® (Alcon Laboratories, Genebra, Suíça) e microscópio Leica M620. Todos os olhos foram submetidos a técnica de pre-chop, dividindo o núcleo em quatro partes. Em 30 olhos, após o pre-chop, foi feita a facoemulsificação dos quadrantes com o modo torsional e, nos outros 30 olhos, após o pre-chop, cada quadrante foi fragmentado com a pinça antes da facoemulsificação com o modo torsional. O aparelho foi calibrado para todos os olhos com os seguintes parâmetros: faco torsional linear 40%; pressão intraocular 65 mmHg; vácuo linear 600mmHg e fluxo de aspiração 40cc/minuto. Após cada procedimento, verificaram-se energia dissipada acumulada; média da amplitude do faco torsional; média equivalente do poder ultrassônico; líquido aspirado estimado; tempo total de ultrassom e tempo total de aspiração. A análise estatística foi realizada utilizando o teste de Kruskal-Wallis com o IBM Statistical Package for Social Sciences. Valor de p<0,05 foi considerado estatisticamente significante. Resultados: Houve redução estatisticamente significante em favor do uso da pinça fragmentadora de núcleo em todos os parâmetros, menos na média de amplitude do faco torsional. Conclusão: O uso da pinça fragmentadora de núcleo contribuiu para melhorar a eficácia do faco torsional em olhos de porco enucleados.

Acceleration of age-induced proteolysis in the guinea pig lens nucleus by in vivo exposure to hyperbaric oxygen: A mass spectrometry analysis.

Hyperbaric oxygen (HBO) treatment of animals or ocular lenses in culture recapitulates many molecular changes observed in human age-related nuclear cataract. The guinea pig HBO model has been one of the best examples of such treatment leading to dose-dependent development of lens nuclear opacities. In this study, complimentary mass spectrometry methods were employed to examine protein truncation after HBO treatment of aged guinea pigs. Quantitative liquid chromatography-mass spectrometry (LC-MS) analysis of the membrane fraction of guinea pig lenses showed statistically significant increases in aquaporin-0 (AQP0) C-terminal truncation, consistent with previous reports of accelerated loss of membrane and cytoskeletal proteins. In addition, imaging mass spectrometry (IMS) analysis spatially mapped the acceleration of age-related αA-crystallin truncation in the lens nucleus. The truncation sites in αA-crystallin closely match those observed in human lenses with age. Taken together, our results suggest that HBO accelerates the normal lens aging process and leads to nuclear cataract.

Differences in the properties of porcine cortical and nuclear fiber cell plasma membranes revealed by saturation recovery EPR spin labeling measurements.

Eye lens membranes are complex biological samples. They consist of a variety of lipids that form the lipid bilayer matrix, integral proteins embedded into the lipid bilayer, and peripheral proteins. This molecular diversity in membrane composition induces formation of lipid domains with particular physical properties that are responsible for the maintenance of proper membrane functions. These domains can be, and have been, effectively described in terms of the rotational diffusion of lipid spin labels and oxygen collision with spin labels using the saturation recovery (SR) electron paramagnetic resonance method and, now, using stretched exponential function for the analysis of SR signals. Here, we report the application of the stretched exponential function analysis of SR electron paramagnetic resonance signals coming from cholesterol analog, androstane spin label (ASL) in the lipid bilayer portion of intact fiber cell plasma membranes (IMs) isolated from the cortex and nucleus of porcine eye lenses. Further, we compare the properties of these IMs with model lens lipid membranes (LLMs) derived from the total lipids extracted from cortical and nuclear IMs. With this approach, the IM can be characterized by the continuous probability density distribution of the spin-lattice relaxation rates associated with the rotational diffusion of a spin label, and by the distribution of the oxygen transport parameter within the IM (i.e., the collision rate of molecular oxygen with the spin label). We found that the cortical and nuclear LLMs possess very different, albeit homogenous, spin lattice relaxation rates due to the rotational diffusion of ASL, indicating that the local rigidity around the spin label in nuclear LLMs is considerably greater than that in cortical LLMs. However, the oxygen transport parameter around the spin label is very similar and slightly heterogenous for LLMs from both sources. This heterogeneity was previously missed when distinct exponential analysis was used. The spin lattice relaxation rates due to either the rotational diffusion of ASL or the oxygen collision with the spin label in nuclear IMs have slower values and wider distributions compared with those of cortical IMs. From this evidence, we conclude that lipids in nuclear IMs are less fluid and more heterogeneous than those in cortical membranes. Additionally, a comparison of properties of IMs with corresponding LLMs, and lipid and protein composition analysis, allow us to conclude that the decreased lipid-to-protein ratio not only induces greater rigidity of nuclear IMs, but also creates domains with the considerably decreased and variable oxygen accessibility. The advantages and disadvantages of this method, as well as its use for the cluster analysis, are discussed.

Visualization of the posterior surface of the lens nucleus with triamcinolone acetonide in phacoemulsification.

PURPOSE: We report a novel technique for visualizing the posterior surface of the lens nucleus during phacoemulsification. SURGICAL TECHNIQUE: Hydro-dissection was performed using a solution of 20 mg triamcinolone acetonide powder without preservatives mixed with 3 ml BSS-plus, and triamcinolone acetonide was clearly identifiable underneath the posterior surface of the lens nucleus. Using a phaco-tip, the nucleus was shaved to the level of the triamcinolone acetonide and could be easily divided. The remnant triamcinolone acetonide was aspirated as much as possible from the lens cortex with an infusion/aspiration tip. SUBJECTS AND EVALUATION TECHNIQUE: Twenty-eight eyes in 28 patients with cataracts were enrolled in this study. Triamcinolone acetonide-assisted phacoemulsification was performed in 13 eyes in 13 patients (triamcinolone acetonide-phacoemulsification group), and normal phacoemulsification was performed in 15 eyes in 15 patients (phacoemulsification group). Intraocular pressure was measured in all patients pre-operatively, 1 day after, and 1 week after surgery. Corneal endothelial cell density was measured pre-operatively and 1 month after surgery. The time of surgical phacoemulsification (surgical phaco time) was measured from the video of the surgery. RESULTS: Surgery was successively performed in all eyes. Pre-operative and post-operative intraocular pressures and cell densities did not significantly differ between the two groups. Surgical phaco time was shorter in the triamcinolone acetonide-phacoemulsification group than in the phacoemulsification group (157.1 ± 51.7 s vs 225.3 ± 45.1 s; p = 0.006). CONCLUSION: The triamcinolone acetonide-assisted phacoemulsification procedure is safe and useful for visualizing the posterior surface of the lens nucleus and facilitates removal of the lens nucleus by phacoemulsification.

Spontaneous full thickness macular hole development and closure in a patient with nucleus dislocation due to hypermature cataract: a case report.

Spontaneous posterior capsule rupture with lens-nucleus dislocation is a very rare entity, as is the development and spontaneous closure of a full thickness macular hole (FTMH) after vitrectomy. The occurrence of these two entities in one eye has not been previously described. A 79-year-old woman was referred because of the right eye intermittent pain and progressive visual loss. Best corrected visual acuity (BCVA) with correction for aphakia was 20/20. Intraocular pressure was normal with therapy. The cornea, anterior chamber, and vitreous were clear. Gonioscopy was normal. The capsular bag was clear, with rolled-up anterior and posterior lens capsule, and the nucleus dislocated in the vitreous. As surgery waiting time was prolonged due to administrative problems, the patient's intraocular pressure (IOP) increased and cystoid macular edema (CME) with lamellar macular hole developed. The patient underwent pars plana vitrectomy with endophacofragmentation and epiretinal membrane peeling. Postoperative optical coherence tomography was normal, BCVA was 20/40, and IOP was normal with topical therapy. One month after surgery, the eye was without signs of inflammation and IOP started rising in spite of maximum therapy. CME reoccurred and progressed to a FTMH, which started closing spontaneously in one month. One year after surgery, IOP normalized and FTMH closed completely. A dislocated crystalline lens in a quiet eye with normal BCVA, which rapidly developed into intractable glaucoma and FTMH, is an unusual finding. The deterioration was followed by spontaneous IOP normalization and macular hole closure. Such unexpected disease course, suggesting a possible autoimmune reaction, has not yet been described.