Spherical aberration reduction in nuclear cataracts.

PURPOSE: To measure higher-order aberrations (HOAs) in nuclear cataracts and to investigate spherical aberration changes with nuclear cataract progression. METHODS: A total of 102 eyes of older subjects (>50 years) were classified based on the nuclear opalescence (NO) grading of the Lens Opacities Classification System III: Group 1 (< NO2, 35), 2 (NO2, 23), 3 (NO3, 23), and 4 (≥ NO 4:21 eyes). Wave front measurements were performed with a Hartmann-Shack aberrometer. To investigate lenticular spherical aberration, HOAs were examined in 28 eyes before and after phacoemulsification, followed by insertion of an aberration-free intraocular lens. The relationship between lens opacity grade and ocular and lenticular spherical aberrations were investigated. RESULTS: Mean spherical aberrations in groups 1, 2, 3, and 4 were 0.25 ± 0.10, 0.16 ± 0.13, 0.12 ± 0.15, and 0.10 ± 0.20 µm, respectively, and showed a significant difference with nuclear opacity grading (p = 0.001). The spherical aberration showed negative associations with nuclear opacity grading (r = -0.408, p < 0.001). The predominant change in HOAs after phacoemulsification was an increase in spherical aberration, and 86 % of lenticular spherical aberrations were presumed to have negative values. The lenticular spherical aberration was negatively correlated with nuclear opacity severity (r = -0.409, p = 0.031). CONCLUSIONS: Ocular spherical aberration decreases with the progression of nuclear cataracts due to the negative correlation between lenticular spherical aberration and nuclear opacity severity.

[Comparison study of new nucleus fragmentation technique in dense cataract phacoemulsification].

Comparison study of new fragmentation technique of dense nucleus in ultrasound phacoemulsification is performed. Proposed method of dense nucleus fragmentation allows to decrease equivalent time of ultrasound exposure using Ozil and NeoSoniX techniques. Minimal loss of corneal posterior epithelial cells was showed in combination of developed nucleus fragmentation technique with torsional phacoemulsification (Ozil). Combination of new fragmentation technique of dense nucleus (IV stage) with Ozil technique results in significant decrease of surgical trauma and time of rehabilitation.

Higher-order aberrations of age-related cataract.

PURPOSE: To analyze higher-order aberrations induced by different types of lenticular opacities. SETTING: Federal University of São Paulo, São Paulo, Brazil. METHODS: One hundred thirty-eyes of 65 patients with bilateral cataract, classified according to the Lens Opacities Classification System III (LOCS III), had complete ophthalmic examinations, corneal topography (EyeSys Technologies), and wavefront analysis (LADARWave, Alcon Laboratories). Patients with cataracts that could not be measured by a Hartmann-Shack sensor or those with coexisting ocular disease were excluded. Higher-order aberrations were compared between the nuclear, cortical, and posterior subcapsular groups for statistical significance. RESULTS: One hundred five eyes of 65 patients were assessed. Twenty-eight eyes (23.33%) had predominantly nuclear opacification (NO1-NO6 and C1-2), and 13 (10.83%) had mainly cortical opacification (C1-4). Sixty-four eyes (65.83%) had a mixed pattern of LOCS III classification, which hindered the establishment of a correlation between the aberrometry and cataract type. Eighteen eyes that presented with dense posterior subcapsular cataract (P4-5) and 7 eyes with cortical C5 LOCS III classification were excluded. In eyes with nuclear opacification, the mean spherical aberration with a 6.0 mm pupil was 0.45 microm +/- 0.17 (SD) and the mean coma was 0.29 +/- 0.13 microm. In eyes with predominantly cortical cataract, the mean spherical aberration was 0.12 +/- 0.10 microm and the mean coma was 0.49 +/- 0.23 microm. The cortical cataract group had statistically significantly higher coma than the other groups (P<.001). The nuclear cataract group had statistically significantly higher spherical aberrations than the other groups (P<.001). CONCLUSIONS: Different types of early lenticular opacities induced different wavefront aberration profiles. Coma predominated in the cortical cataract group, and spherical aberration predominated in the nuclear cataract group.

[Characteristics of non invasive ultrasound determination of mechanical lens hardness].

Sixty-two patients with varying maturity cataract were examined to assess a new noninvasive method for determining the mechanical hardness of the nucleus of the lens. There was an inverse relation of the hardness of the nucleus to its relative acoustic density (delta). Comparison of the ultrasound density of the lens and the mechanical characteristics of its nucleus has provided the following classification: the lens hardness is high at delta of 0 to 0.2; average at 0.3 to 0.5, and low at 0.6 or higher. Determination of relative acoustic density by measuring the parameter delta substantially enhances the accuracy ofpreoperative prediction of the hardness of the nucleus of the lens when a surgical option for cataract removal is chosen.

Scheimpflug lens densitometry and ocular wavefront aberrations in patients with mild nuclear cataract.

PURPOSE: To test correlations between Scheimpflug optical densitometry and ocular higher-order aberrations (HOAs) in patients with mild nuclear cataract. SETTING: Cornea and Refractive Surgery Department, Hospital de Braga, Braga, Portugal. DESIGN: Retrospective single-center study. METHODS: In eyes with mild nuclear cataract, lens densitometry was evaluated by Scheimpflug imaging (Pentacam HR), which provided an objective quantification (mean density and maximum density) and grading (nuclear staging score) of the crystalline lens. A visual function analyzer that combines ray-tracing aberrometry and Placido disk-based topography (iTrace) was used to evaluate the total ocular and internal HOAs. RESULTS: The study comprised 40 eyes of 30 patients. The mean density of the lens nucleus was 8.99% ± 0.76% (SD) (range 7.5% to 10.8%), and the mean maximum density was 27.96% ± 6.97% (range 16.9% to 56.1%). Regarding the score of nuclear staging of the Scheimpflug device, 28 eyes had level 0 and 12 eyes had level 1. Significant positive correlations were found between the mean density and maximum density parameters and the internal HOAs (ρ = 0.661, P < .001 and ρ = 0.570, P < .001, respectively). CONCLUSIONS: There were significant correlations between the quantification parameters derived from Scheimpflug lens densitometry and ocular HOAs. The integration of these technologies can help in clinical decision making and in understanding the subjective symptoms of patients with mild nuclear cataracts. FINANCIAL DISCLOSURE: Dr. Ambrósio is a consultant to Oculus Optikgeräte GmbH, Alcon Surgical, Inc., and Carl Zeiss Meditec AG. None of the other authors has a financial or proprietary interest in any material or method mentioned.

Long-term nutrient intake and 5-year change in nuclear lens opacities.

OBJECTIVE: To determine if usual nutrient intake is related to a 5-year change in the amount of lens nuclear opacification assessed by computer-assisted image analysis. DESIGN: A sample of 408 Boston, Mass-area women from the Nurses' Health Study aged 52 to 74 years at baseline participated in a 5-year study related to nutrition and vision. Usual nutrient intake was calculated as the average intake from 5 food frequency questionnaires that were collected over a 13- to 15-year period before the baseline evaluation of lens nuclear density. Duration of vitamin supplement use before baseline was determined from 7 questionnaires collected during this same period. We assessed the degree of nuclear density (opacification) using computer-assisted image analysis of digital lens images with amount of nuclear density measured as a function of average pixel gray scale, ranging from 0 (clear) to 255 (black). RESULTS: Median (range) baseline and follow-up nuclear densities were 44 (19 to 102) and 63 (32 to 213). The median (range) 5-year change in nuclear density was 18 (-29 to 134) and was positively correlated with the amount of opacification at baseline (Spearman correlation coefficient = 0.35; P<.001). Geometric mean 5-year change in nuclear density was inversely associated with the intake of riboflavin (P trend = .03) and thiamin (P trend = .04) and duration of vitamin E supplement use (P trend = .006). CONCLUSION: Our results suggest that long-term use of vitamin E supplements and higher riboflavin and/or thiamin intake may reduce the progression of age-related lens opacification.

Influence of type and severity of pure forms of age-related cataract on visual acuity and contrast sensitivity. Italian American Cataract Study Group.

PURPOSE: To compare the relationship between logMAR visual acuity (VA) and cataract severity and between contrast sensitivity (CS) and cataract severity in pure types of age-related lens opacities. METHODS: Analysis included patients followed in the ongoing Italian-American Study of the Natural History of Age-Related Cataract. Lens opacities were classified and graded according to the Lens Opacities Classification System II (LOCS II). Visual acuity was measured with the Early Treatment Diabetic Retinopathy Study Chart. Contrast sensitivity was measured with the Pelli-Robson chart. RESULTS: Data from 1,076 eyes were used for the analysis (366 clear lenses; 550, 124, and 36 eyes with cortical, nuclear and posterior subcapsular cataract, respectively). In age-adjusted analyses, increasing severity of all three cataract types was associated with progressively higher logMAR VA, which translates into poorer acuity, and lower CS scores. For both VA and CS, the effect of increasing severity was greatest for nuclear and least for cortical opacities. After adjusting for age and VA, CS scores were no longer associated with cataract type and severity, with the exception of advanced cortical opacities. CONCLUSIONS: Increased cataract severity, as determined by LOCS II grading, is strongly associated with both VA and CS scores. Contrast sensitivity scores obtained from testing at low spatial frequency do not seem to offer additional information over standard VA testing in early cortical and posterior subcapsular opacities nor in nuclear cataracts.

Glutathione peroxidase-1 deficiency leads to increased nuclear light scattering, membrane damage, and cataract formation in gene-knockout mice.

PURPOSE: Previous in vitro studies with transgenic and gene-knockout mice have shown that lenses with elevated levels of glutathione peroxidase (GPX)-1 activity are able to resist the cytotoxic effect of H(2)O(2), compared with normal lenses and lenses from GPX-1-deficient animals. The purpose of this study was to investigate the functional role of this enzyme in antioxidant mechanisms of lens in vivo by comparing lens changes of gene-knockout mice with age-matched control animals. METHODS: In vivo lens changes were monitored by slit lamp biomicroscopy, and enucleated lenses were examined under a stereomicroscope in gene-knockout animals and age-matched control animals ranging in age from 3 weeks to 18 months. Transmission (TEM) and confocal microscopy were performed on different regions of lenses after the mice were killed at various times. RESULTS: Slit lamp images showed an increase in nuclear light scattering (NLS) in gene-knockout mice compared with control animals. TEM revealed changes in the nucleus as early as 3 weeks of age by the appearance of waviness of fiber membranes. With increasing age, there was greater distortion of fiber membranes and distension of interfiber space at the apex of fiber cells compared with control mice. The changes in nuclear fiber membranes were even more dramatic, as observed by confocal microscopy, which was performed on thicker sections. In contrast to the changes in the lens nucleus, the morphology of the epithelium and superficial cortex remained unchanged in knockout animals during the same experimental period, consistent with slit lamp observations. Stereomicroscopy of ex vivo lenses demonstrated a significant increase in opacification in gene-knockout mice relative to control animals of the same age. This effect became evident in mice aged 5 to 9.9 months and persisted thereafter in older animals, resulting in mature cataracts after 15 months. CONCLUSIONS: The results demonstrate the critical role of GPX-1 in antioxidant defense mechanisms of the lens nucleus. The increased NLS appears to be associated with damage to fiber membranes in the nucleus, which is particularly susceptible to oxidative challenge because of the deficiency of GPX-1. It is suggested that the lens membrane changes in the knockout animals may be due to the formation of lipid peroxides, which serve as substrates for GPX-1. Cataract development in gene-knockout mice appeared to progress from focal opacities, apparent at an earlier age, to lamellar cataracts between 6 and 10 months, and finally to complete opacification in animals older than 15 months. This is the first reported phenotype in GPX-1-knockout mice.

Loss of heterozygosity in patients with pseudoexfoliation syndrome.

PURPOSE: The purpose of the study was to evaluate the possible occurrence of loss of heterozygosity (LOH) in the anterior capsule, lens nucleus, iris, and trabeculum samples taken from patients with pseudoexfoliation syndrome (PEX). Loss of heterozygosity in a microsatellite marker locus indicates that the neighboring gene may be inactivated. Previous attempts to find a gene defect that might be responsible for pseudoexfoliation glaucoma have been unsuccessful. METHODS: Specimens of the anterior capsule, the lens nucleus, the iris, the trabeculum, and reference blood samples were collected from 19 PEX patients. Fluorescent multiplex PCR was used to amplify the microsatellite markers located on chromosomes 2, 4, 7, 12, 18, 19, and 21. RESULTS: LOH was found in 58% of the iris specimens and 50% of the anterior capsule specimens collected from PEX patients. The highest incidence of LOH was observed at the marker D7S820. CONCLUSIONS: It is possible, that genetic factors may be involved in the etiology and pathogenesis of PEX.

Assessment of nuclear sclerosis after nonvitrectomizing vitreous surgery.

PURPOSE: Nuclear sclerosis develops frequently after successful pars plana vitrectomy. We evaluated changes in the degree of nuclear sclerosis after nonvitrectomizing vitreous surgery for idiopathic epimacular proliferation. METHODS: Forty-one consecutive patients (41 eyes) underwent removal of idiopathic epimacular proliferation by nonvitrectomizing vitreous surgery and were followed postoperatively for at least 12 months. Visual acuity, refractive error, slit-lamp biomicroscopy, and Scheimpflug photographs were assessed preoperatively and postoperatively to evaluate changes in the degree of lenticular opacification. Quantitative analysis of the nuclear sclerosis was performed by densitometry with Scheimpflug photographs performed on only the last 21 patients. We evaluated these measurements by comparing statistically the preoperative and postoperative difference between both eyes (operative eye minus nonoperative ocular data). RESULTS: There was no significant difference in the progression of nuclear sclerosis or degree of myopic shift between the operated and fellow eyes during postoperative follow-up (mean +/- SD, 22 +/- 8 months; median, 22 months; range, 12 to 48 months). The average preoperative and postoperative refractive errors in operated eyes were 0.0 +/- 2.4 diopters and 0.1 +/- 2.5 diopters, respectively; the average difference in the refractive errors between both eyes was -0.2 +/- 0.7 diopter preoperatively and -0.2 +/- 0.9 diopter postoperatively (P =.961, paired t test). The average preoperative and postoperative nuclear density values by Scheimpflug photography in 21 operated eyes were, respectively, 72 +/- 18 nuclear density units and 75 +/- 17 nuclear density units; the average difference in nuclear density values between both eyes was -1 +/- 4 nuclear density units preoperatively and 0 +/- 6 nuclear density units postoperatively (P =.631, paired t test). CONCLUSION: Progression of nuclear sclerotic cataract based on changes in refractive error and Scheimpflug photography was not observed after nonvitrectomizing vitreous surgery.

Changes in the internal structure of the human crystalline lens with age and accommodation.

Scheimpflug images were made of the unaccommodated and accommodated right eye of 102 subjects ranging in age between 16 and 65 years. In contrast with earlier Scheimpflug studies, the images were corrected for distortion due to the geometry of the Scheimpflug camera and the refraction of the cornea and the lens itself. The different nuclear and cortical layers of the human crystalline lens were determined using densitometry and it was investigated how the thickness of these layers change with age and accommodation. The results show that, with age, the increase in thickness of the cortex is approximately 7 times greater than that of the nucleus. The increase in thickness of the anterior cortex was found to be 1.5 times greater than that of the posterior cortex. It was also found that specific parts of the cortex, known as C1 and C3, showed no significant change in thickness with age, and that the thickening of the cortex is entirely due to the increase in thickness of the C2 zone. With age, the distance between the sulcus (centre of the nucleus) and the cornea does not change. With accommodation, the nucleus becomes thicker, but the thickness of the cortex remains constant.

Initial experience with the HydroSonics instrument to soften cataracts before phacoemulsification.

An ultrasonically driven needle placed into the body of the nucleus, with subsequent injection of balanced salt solution (BSS), can be used to fragment the nucleus into sections or lamellae that can potentially be emulsified with greater ease and less ultrasound energy delivered to the eye. This separation of the nucleus has been designated hydrodelineation. The six surgeons participating in this study subjectively reported that the use of hydrodelineation facilitated phacoemulsification, on average, in 91% of their cases. Review of study data indicated that significantly less ultrasound time and cumulative displayed energy were noted in phacoemulsification of grade 2+ and 3+ cataracts after hydrodelineation than in cases in which hydrodelineation was not performed. The results in cases performed with and without hydrodelineation were statistically equivalent in complications and postoperative patient outcomes.

Efficacy and safety of the soft-shell technique in cases with a hard lens nucleus.

PURPOSE: To evaluate the efficacy and safety of the soft-shell technique in reducing corneal endothelial cell damage during cataract surgery in patients with a hard lens nucleus. SETTING: Miyata Eye Hospital, Miyakonojo, Miyazaki, Japan. METHODS: Sixty eyes of 57 cataract patients with a hard lens nucleus (Emery-Little classification grade 3 or higher) had phacoemulsification using the soft-shell technique with Healon((R)) (sodium hyaluronate 1%) and Viscoat (sodium hyaluronate 3.0%-chondroitin sulfate 4.0%) (soft-shell group) or with Healon alone (control group). The visual acuity, intraocular pressure (IOP), flare intensity in the anterior chamber, central corneal thickness, and corneal endothelial cell density were evaluated postoperatively. RESULTS: There were no significant IOP elevations in either group. The mean central corneal thickness in the control group was 539 microm +/- 26.0 (SD) preoperatively and 578 +/- 52.0 microm 1 day after surgery; the increase was significant (P =.0154). There was no significant change in the central corneal thickness in the soft-shell group. There were no statistically significant differences between the 2 groups in uncorrected visual acuity, best corrected visual acuity, IOP, flare intensity in the anterior chamber, and central corneal thickness throughout the follow-up. The rate of endothelial cell loss 3 months after surgery was 6.4% +/- 9.6% in the soft-shell group and 16.3% +/- 9.8% in the control group (P =.0003). CONCLUSION: The results suggest that the soft-shell technique is safe and effective in protecting corneal endothelial cells during cataract surgery in patients with a hard lens nucleus.

Comparison of various calpain inhibitors in reduction of light scattering, protein precipitation and nuclear cataract in vitro.

PURPOSE: To compare effects of calpain inhibitors on in vitro light-scattering in rat lens soluble protein and calcium-ionophore (A23187)-induced cataract formation in cultured rat lenses. METHODS: Rat lens soluble protein was hydrolyzed for 24 hours by activation of endogenous lens calpain. Ten calpain inhibitors were tested in this model at 10 and 25 microM concentration. As an index of protein precipitation, light scattering was measured daily at 405 nm for 8 days. Lens proteins were analyzed by isoelectric-focussing. Subsequently, rat lenses were cultured for 5 days with 10 microM A23187. Calpain inhibitors (SJA6017, MDL28170, AK295 and PD150606), which inhibited light-scattering were tested at 100 microM concentration in this model. Cataract evaluation, isoelectric-focussing and calcium determinations were performed. RESULTS: At 25 microM concentration AK295, SJA6017, E-64, PD-150606 and MDL28170 produced greater than 25% inhibition of light-scattering. Isoelectric-focussing revealed that addition of Ca(2+) produced characteristic crystallin proteolysis and aggregation patterns. AK295, SJA6017, MDL28170 and E64c prevented these changes. Lenses cultured in A23187 exhibited nuclear cataract, elevated calcium and proteolysis and aggregation of crystallins. Co-culture with SJA6017, MDL28170 and E64c reduced A23187-induced nuclear opacities, proteolysis and aggregation of crystallins without affecting increased total calcium. CONCLUSIONS: Endogenous calpain-activation model and A23187-induced cataract model can be used sequentially to screen calpain inhibitors for potential anti-cataract activity. Proteolytic changes in lens cortex after exposure to A23187 are also due to calpain activation. AK295, SJA6017 and MDL28170 possess efficacy against calcium-induced models of rodent cataracts. Use of calpain inhibitors represents a promising approach to cataract therapy.

On the correlation of mechanical and optical properties of cataractous eye lens nuclei.

It is investigated whether mechanical properties of human cataractous eye lens nuclei can be assessed by their optical ones. This question is of importance as the success of phacoemulsification surgery among other criteria depends on the mechanical properties of the lens nucleus. The mechanical and optical properties of senile cataractous human eye lens nuclei were tested in vitro after extracapsular cataract extraction. A new measurement system was developed to determine their mechanical response. Hereby, a force is applied to the specimen and the resultant displacement is measured or vice versa. Stiffness and ultimate strength of the material are determined. Optical transmission is detected in dependence of light wavelength by a spectrophotometer. In addition the nuclear colour is determined. The correlation of mechanical stiffness and strength via optical transmission at 550 nm and nuclear colour is analyzed. Human eye lens nuclei show a viscoelastic mechanical behaviour. Measurement of stiffness is reproducible after 5-6 loading cycles when a steady-state is reached. Mechanical and optical properties correlate weakly but significantly. Stiffness and strength increase with increasing nuclear coloration. Alterations of mechanical and optical properties are caused by the same structural changes of the molecular components of the ageing lens. Especially lens crystallines are responsible for this process. Thus, it is concluded that optical properties can be useful to assess the mechanical response of cataractous eye lens nuclei.

Comparative analysis of the nuclear lens opalescence by the Lens Opacities Classification System III with nuclear density values provided by Oculus Pentacam: a cross-section study using Pentacam Nucleus Staging software.

PURPOSE: To compare the clinical classification of cataract using the Lens Opacities Classification System (LOCS) III with the mean values of lens density provided by the Pentacam Scheimpflug System in nuclear cataracts. METHODS: One hundred and one eyes from 101 patients with age-related nuclear cataract were submitted to clinical examination for lens grading score using LOCS III. According to LOCS III, nuclear opalescence was divided in six groups. Patients were evaluated by the Pentacam Scheimpflug System for the mean lens density using the Pentacam lens densitometry program (PLDP), the Pentacam Nucleus Staging (PNS) mean value and the PNS cataract grading score. RESULTS: A positive correlation between the mean values of lens density and LOCS III classification, considering groups 1 to 5, could be noticed with PLDP and PNS mean value. The mean values between the groups were similar using the PLDP and the PNS mean value. However, when the PNS cataract grading score was evaluated, there was low correspondence with LOCS III classification. CONCLUSION: Pentacam Scheimpflug device offers an objective measure of the lens nuclear density on nuclear cataracts. PLDP and the PNS mean value were both useful to evaluate age-related nuclear cataract up to LOCS III group 5.

Use of cobalt blue light in grading cataract and estimating vision loss.

PURPOSE: To test an anecdotally reported cataract grading system predictive of a 20/50 visual threshold in cataract-induced vision loss using cobalt blue light. SETTING: Hennepin County Medical Center, Minneapolis, Minneapolis VA Medical Center, Minneapolis, and Regions Hospital, St. Paul, Minnesota, USA. METHODS: Four observers evaluated pure nuclear cataracts using a standardized cobalt-blue-light protocol. Observers graded a nuclear cataract as positive if the posterior capsule was visualized with cobalt blue light and negative if the posterior capsule was not visualized. Results of the grading were compared with cataract-induced vision loss in an attempt to establish a threshold for lost visual acuity in grading cataracts with cobalt blue light. The study design was prospective observation of a cohort with a visually significant cataract. RESULTS: This study did not show a clear visual acuity threshold for cataract-induced vision loss using a standardized cobalt-blue-light protocol. Overall, 26.3% (95% confidence interval, 13.4-40.2) of all 20/40 or less dense nuclear cataracts had visible posterior capsules using cobalt blue light, with good estimated interobserver agreement. CONCLUSIONS: Although cobalt blue light is selectively absorbed by yellow pigment in an aging nuclear cataract, its ability to predict visual acuity loss due to lens opacity was limited.

Correlation of lens density measured using the Pentacam Scheimpflug system with the Lens Opacities Classification System III grading score and visual acuity in age-related nuclear cataract.

AIMS: To investigate the relationship between lens density measured with the Pentacam Scheimpflug System and grading score using the Lens Opacities Classification System (LOCS) III as well as that between lens density and visual acuity in age-related nuclear cataract patients. METHODS: Lens density and grading score were evaluated in 138 cases (180 eyes) with age-related nuclear cataract. LogMAR visual acuity was tested with the Early Treatment Diabetic Retinopathy Study chart. The correlations between lens density value and LOCS III nuclear opacity (NO) and nuclear colour (NC) grading score and that between lens density value and logMAR visual acuity were analysed. RESULTS: There was a linear increasing relationship between lens density value and LOCS III grading score in nuclear cataract patients. Lens density value had a stronger significant correlation with LOCS III NO score than that with NC score. The correlation between the nuclear lens density value and logMAR visual acuity was stronger than that between NO score and logMAR visual acuity or between NC score and logMAR visual acuity. CONCLUSION: Lens density as a quantitative and objective parameter can present the degree of NO and associated visual impairment due to nuclear cataract. The LOCS III criterion as an economic cataract grading system provides data that are in satisfactory concordance with the results obtained using the Pentacam Scheimpflug system.

Presbyopia: the first stage of nuclear cataract?

Presbyopia, the inability to accommodate, affects almost everyone at middle age. Recently, it has been shown that there is a massive increase in the stiffness(1) of the lens with age and, since the shape of the lens must change during accommodation, this could provide an explanation for presbyopia. In this review, we propose that presbyopia may be the earliest observable symptom of age-related nuclear (ARN) cataract. ARN cataract is a major cause of world blindness. The genesis of ARN cataract can be traced to the onset of a barrier within the lens at middle age. This barrier restricts the ability of small molecules, such as antioxidants, to penetrate into the centre of the lens leaving the proteins in this region susceptible to oxidation and post-translational modification. Major protein oxidation and colouration are the hallmarks of ARN cataract. We postulate that the onset of the barrier, and the hardening of the nucleus, are intimately linked. Specifically, we propose that progressive age-dependent hardening of the lens nucleus may be responsible for both presbyopia and ARN cataract.

Comparative analysis of the nuclear lens opalescence by the Lens Opacities Classification System III with nuclear density values provided by Oculus Pentacam: a cross-section study using Pentacam Nucleus Staging software / Análise comparativa da opalencência nuclear cristaliniana pelo Lens Opacities Classification System III com valores de densidade nuclear fornecidos pelo Oculus Pentacam: estudo transversal utilizando o Pentacam Nucleus Staging software

PURPOSE: To compare the clinical classification of cataract using the Lens Opacities Classification System (LOCS) III with the mean values of lens density provided by the Pentacam Scheimpflug System in nuclear cataracts. METHODS: One hundred and one eyes from 101 patients with age-related nuclear cataract were submitted to clinical examination for lens grading score using LOCS III. According to LOCS III, nuclear opalescence was divided in six groups. Patients were evaluated by the Pentacam Scheimpflug System for the mean lens density using the Pentacam lens densitometry program (PLDP), the Pentacam Nucleus Staging (PNS) mean value and the PNS cataract grading score. RESULTS: A positive correlation between the mean values of lens density and LOCS III classification, considering groups 1 to 5, could be noticed with PLDP and PNS mean value. The mean values between the groups were similar using the PLDP and the PNS mean value. However, when the PNS cataract grading score was evaluated, there was low correspondence with LOCS III classification. CONCLUSION: Pentacam Scheimpflug device offers an objective measure of the lens nuclear density on nuclear cataracts. PLDP and the PNS mean value were both useful to evaluate age-related nuclear cataract up to LOCS III group 5.

OBJETIVO: Comparar a classificação clínica de catarata nuclear, utilizando o Lens Opacities Classification System (LOCS) III, e o valores médios de densidade nuclear fornecido pelo sistema Pentacam Sheimpflug. MÉTODOS: Cento e um pacientes (101 olhos) com diagnóstico de catarata nuclear senil foram submetidos a exame clínico para graduação da opalescência nuclear de acordo com o LOCS III e divididos em seis grupos de acordo com a mesma. Os pacientes foram posteriormente avaliados pelo sistema Pentacam Scheimpflug para obtenção do valor médio de densidade fornecido pelo programa de densitometria cristaliniana do aparelho (PLDP), valor médio de densidade calculado pelo Pentacam Nucleus Staging software (PNS) e o escore de graduação de catarata nuclear fornecido pelo PNS. RESULTADOS: Observou-se uma correlação positiva entre os valores médios de densidade cristaliniana fornecidos pelo PLDP e PNS e a classificação clínica LOCS III, considerando os grupos 1 ao 5. Os valores médios de densidade nuclear de cada grupo foram similares utilizando dados do PLDP e PNS. Entretanto, quando foi analisado o escore de graduação da catarata fornecido pelo PNS foi observada uma baixa correspondência com a classificação LOCS III. CONCLUSÃO: O Pentacam Scheimpflug oferece uma medida objetiva da densidade nuclear cristaliniana em cataratas nucleares. Os valores médios de densidade nuclear fornecidos pelo PLDP e PNS foram úteis na avaliação de catarata nuclear senil até o grupo 5 da classificação LOCS III.