Repositioning of in-the-bag Dislocated Intraocular Lenses: A Randomized Clinical Trial Comparing Two Surgical Methods.

INTRODUCTION: The aim of this study was to evaluate intraocular lens (IOL) tilt, IOL-induced astigmatism (IIA), refractive change, and impact of capsular fibrosis on IOL position after scleral fixation of dislocated IOL using two methods: ab externo scleral suture loop fixation (group A) and a modification, embracing the continuous curvilinear capsulorhexis (group B). METHODS: In this prospective randomized clinical trial conducted at St. Erik Eye Hospital, 117 patients with dislocated IOL were randomized to group A (n = 61) or B (n = 56). Patients with ordinary pseudophakia (n = 60) served as controls. IOL tilt was measured three-dimensionally with anterior segment optical coherence tomography (AS-OCT). RESULTS: The median IOL tilt was similar with both methods (A: 7.8°; B: 8.3°; p = 0.51) but higher than in ordinary pseudophakia (5.4°; p < 0.001). Both groups showed a myopic shift, p < 0.001. In cases without capsular fibrosis, the median IOL tilt was 15.5° in group A (n = 7) and 7.0° in group B (n = 5), p = 0.19. For each degree of IOL tilt, IIA increased by 0.075 D (p < 0.001). IOL position could be measured with AS-OCT in all patients given that the IOL was visible in the pupil. CONCLUSION: After IOL fixation surgery, IOL tilt is higher than in normal pseudophakia. A study involving more patients without capsular fibrosis could clarify whether IOL position is better with method B in this subgroup. IAA is low, but myopic shift is common. AS-OCT is useful for IOL tilt assessment after IOL fixation surgery.

A Composite Risk Score for Capsule Complications Based on Data from the Swedish National Cataract Register: Relation to Surgery Volumes.

PURPOSE: To investigate case mix in relation to capsule complication, possible associations between case mix and operation volume, and change in case mix over time. DESIGN: Register-based study. PARTICIPANTS: Swedish patients who underwent cataract surgery between 2007 and 2016. METHODS: Demographics and data on ocular comorbidity, intraoperative difficulties, and capsule complications were registered from 2007 to 2016 and analyzed retrospectively in relation to coded data on individual surgeons' operation volume. Single factor analysis and logistic regression were performed, and a composite risk score was created. MAIN OUTCOME MEASURES: Risk of capsule complication, given as adjusted and composite odds ratio in relation to cataract surgery volume. RESULTS: Preoperative and intraoperative variables significantly associated with capsule complications were best-corrected visual acuity (BCVA) ≤0.1 (decimal, adjusted odds ratio [aOR], 1.82; P < 0.001); pseudoexfoliation (PEX) (aOR, 1.53; P < 0.001); sight-threatening ocular comorbidity other than age-related macular degeneration (AMD), diabetic retinopathy, glaucoma, or cornea guttata (aOR, 1.35; P = 0.006); use of Trypan blue (aOR, 1.76; P < 0.001); mechanical pupil dilation (aOR, 1.36; P = 0.024); and iris hooks at the rhexis margin (aOR, 6.99; P < 0.001). The composite risk score was 3.09 ± 6.40 (mean ± standard deviation) for patients with capsule complication and 1.28 ± 1.66 for uncomplicated procedures (P < 0.001). High-volume cataract surgeons (≥500 procedures yearly) had a significantly lower composite risk score (mean risk score ≤1.28; range, 1.01-2.02) compared with low- and medium-volume cataract surgeons (1.34 ± 0.56; range, 1.00-4.55 and 1.49 ± 0.58; range, 1.01-5.19), respectively. During the period 2007-2016, the proportion of patients aged >88 years, patients with BCVA ≤0.1, and patients with intraoperative difficulties decreased. CONCLUSIONS: Case mix, as calculated from a composite risk score based on preoperative and intraoperative parameters registered in the National Cataract Register (NCR), may contribute to the decrease in capsule complications from 2007 to 2016 and the lower complication rate observed in cases managed by high-volume cataract surgeons.

Cataract Surgery Volumes and Complications per Surgeon and Clinical Unit: Data from the Swedish National Cataract Register 2007 to 2016.

PURPOSE: To investigate the change in proportion of high-volume cataract surgeons during the period 2007 to 2016 and determine the impact of operation volume per surgeon and clinical unit on the rate of capsule complications. DESIGN: Retrospective, register-based study. PARTICIPANTS: Patients undergoing and surgeons performing cataract surgery at Swedish ophthalmologic departments 2007-2016. METHODS: All cataract procedures performed during a 10-year period were analyzed, and the change in operation volume of individual surgeons over time was determined. The yearly incidence of capsule complications was correlated to the operation volume of individual surgeons and clinical units. MAIN OUTCOME MEASURES: The number of cataract procedures yearly per surgeon and clinical unit, proportion of capsule complications, and change over time in operation volume and complication rate. RESULTS: The proportion of high-volume (≥500 procedures yearly) and very high-volume (≥1000 procedures yearly) surgeons increased from 15.0% to 34.0% and 2.1% to 10.9%, respectively (P < 0.001 for both categories). The proportion of all cataract procedures performed by high-volume surgeons was 36.9% in 2007, increasing to 68.1% in 2016. The yearly incidence of capsule complications decreased with increasing number of procedures; from a mean of 2.15% (standard deviation [SD], 3.17) for low-volume surgeons (10-99 procedures/year) to 1.32% (1.28) for medium-volume (100-499 procedures/year) surgeons and 0.59% (0.49) for high-volume surgeons (P = 0.016). Preoperative best-corrected visual acuity was significantly better in eyes operated on by high-volume and very high-volume cataract surgeons; the median best-corrected visual acuity (BCVA) was 0.5 (decimal) compared with a BCVA of 0.4 for patients who had their surgery performed by low- or medium-volume surgeons (overall P < 0.001). No significant difference in rate of capsule complications was seen between clinical units with high or low operation volume (P = 0.804). The overall incidence of capsule complications decreased gradually from 1.5% in 2007 to 0.8% in 2016, and preoperative BCVA increased from 0.46±0.10 (logarithm of the minimum angle of resolution) to 0.40±0.05 (P = 0.030). CONCLUSIONS: There is a strong association of rate of capsule complications with operation volume of individual surgeons but not with operation volume of individual clinical units. The decreased rate of capsule complications seen between 2007 and 2016 may be explained in part by a dramatic increase in the proportion of high-volume cataract surgeons during the period.

Safety and efficacy of a standardized intracameral combination of mydriatics and anesthetic for cataract surgery in type-2 diabetic patients.

BACKGROUND: Cataract surgery in diabetics is more technically challenging due to a number of factors including poor intraoperative pupil dilation and a higher risk of vision threatening complications. This study evaluates the safety and efficacy of an intracameral combination of 2 mydriatics and 1 anesthetic (ICMA, Mydrane) for cataract surgery in patients with well-controlled type-2 diabetes. METHODS: Post-hoc subgroup analysis of a phase 3 randomized study, comparing ICMA to a conventional topical regimen. Data were collected from 68 centers in Europe and Algeria. Only well-controlled type-2 diabetics, free of pre-proliferative retinopathy, were included. The results for non-diabetics are also reported. The primary efficacy variable was successful capsulorhexis without additional mydriatic treatment. Postoperative safety included adverse events, endothelial cell density and vision. RESULTS: Among 591 randomized patients, 57 (9.6%) had controlled type 2 diabetes [24 (42.1%) in the ICMA Group and 33 (57.9%) in the Topical Group; intention-to-treat (ITT) set]. Among diabetics, capsulorhexis was successfully performed without additional mydriatics in 24 (96.0%; modified-ITT set) patients in the ICMA Group and 26 (89.7%) in the Topical Group. These proportions were similar in non-diabetics. No diabetic patient [1 (0.5%) non-diabetics] in the ICMA Group had a significant decrease in pupil size (≥3 mm) intraoperatively compared to 4 (16.0%; modified-ITT set) diabetics [16 (7.3%) non-diabetics] in the Topical group. Ocular AE among diabetics occurred in 2 (8.0%; Safety set) patients in the ICMA Group and 5 (16.7%) in the Topical Group. Endothelial cell density at 1 month postoperatively was similar between groups in diabetics (P = 0.627) and non-diabetics (P = 0.368). CONCLUSIONS: ICMA is effective and can be safely used in patients with well-controlled diabetes, with potential advantages compared to a topical regimen including reduced systemic risk, better corneal integrity and reduced risk of ocular complications. TRIAL REGISTRATION: The trial was registered at (reference # NCT02101359) on April 2, 2014.

Analysis of long-term visual quality with numerical 3D ray tracing after corneal crosslinking treatment.

A numerical 3D ray tracing model was used to evaluate the long-term visual effects of two regimens of corneal crosslinking (CXL) treatment of 48 patients with the corneal degeneration keratoconus. The 3D ray tracing analyses were based on corneal elevation data measured by Scheimpflug photography. Twenty-two patients were treated with standard CXL applied uniformly across the corneal surface, whereas 26 patients underwent a customized, refined treatment only at local zones on the cornea (photorefractive intrastromal CXL; PiXL). Spot diagrams, spot root-mean-square (RMS) values, and Strehl ratios were evaluated for the patients prior to and 1, 3, 6, and 12 months after treatment. It was found that the group of patients treated with PiXL, on average, tended to attain a long-term improvement of the corneal optical performance, whereas only minor changes of the optical parameters were found for group treated with standard CXL. Our results confirmed that standard CXL treatment stabilizes the corneal optical quality over time, and thus halts the progression of the corneal degeneration. In addition to stabilization, the results showed that a significantly higher proportion of subjects treated with PiXL improved in RMS, 3, 6, and 12 months after treatment, compared to with CXL (p<0.05). This finding indicates that the PiXL treatment might improve optical quality over time.

Three-dimensional ray-tracing model for the study of advanced refractive errors in keratoconus.

We propose a numerical three-dimensional (3D) ray-tracing model for the analysis of advanced corneal refractive errors. The 3D modeling was based on measured corneal elevation data by means of Scheimpflug photography. A mathematical description of the measured corneal surfaces from a keratoconus (KC) patient was used for the 3D ray tracing, based on Snell's law of refraction. A model of a commercial intraocular lens (IOL) was included in the analysis. By modifying the posterior IOL surface, it was shown that the imaging quality could be significantly improved. The RMS values were reduced by approximately 50% close to the retina, both for on- and off-axis geometries. The 3D ray-tracing model can constitute a basis for simulation of customized IOLs that are able to correct the advanced, irregular refractive errors in KC.

Oestradiol levels and superoxide dismutase activity in age-related cataract: a case-control study.

BACKGROUND: It has been suggested that the higher prevalence of cataract in women is caused by a withdrawal effect of oestrogen at menopause. In vitro studies have demonstrated protection of serum oestradiol (E2) against oxidative stress through upregulation of antioxidant enzymes, including superoxide dismutase (SOD). The purpose of the present study was to investigate E2 levels and SOD erythrocyte activity in patients with age-related cataract. METHODS: The studied subjects consisted of 103 patients with age-related cataract and 22 controls. Cataracts were classified as nuclear, cortical, or posterior subcapsular. Blood samples were collected and data on smoking, hormonal use, diabetes and age at menarche/menopause was obtained for all individuals. Serum oestradiol analyses were performed with radioimmunoassay (RIA) and SOD activity was measured in erythrocyte lysates. RESULTS: A negative correlation between age and E2 concentration was seen in a linear regression analysis. No correlation was seen between SOD activity and age or gender and no correlation between E2 levels and SOD activity was found using multiple linear regression. The mean level of E2 for all male subjects was 50.1 ± 16.3 pmol/L, significantly higher compared to 13.8 ± 11.8 pmol/L for postmenopausal women. CONCLUSION: The present study does not support a role for E2-induced effects on SOD in cataract formation. The findings of higher E2 levels in men than in postmenopausal women may suggest that decreased oestrogen at menopause is partially responsible for the gender-related difference in cataract prevalence. However, the latter can only be verified through prospective randomized trials using hormonal replacement therapy.

Can we trust intraocular pressure measurements in eyes with intracameral air?

PURPOSE: To evaluate the effect of intracameral air on intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) in an in-vitro porcine eye model. METHODS: IOP was measured on thirteen freshly enucleated eyes at three reference pressures: 20, 30, and 40 mmHg. Six measurements/method were performed in a standardized order with GAT and ART respectively. Air was injected intracamerally in the same manner as during Descemet's stripping endothelial keratoplasty (DSEK) and Descemet's membrane endothelial keratoplasty (DMEK), and the measurements were repeated. RESULTS: Measured IOP increased significantly for both tonometry methods after air injection: 0.7 ± 2.1 mmHg for GAT and 10.6 ± 4.9 mmHg for ART. This difference was significant at each reference pressure for ART but not for GAT. CONCLUSIONS: Although slightly affected, this study suggests that we can trust GAT IOP-measurements in eyes with intracameral air, such as after DSEK/DMEK operations. Ultrasound-based methods such as ART should not be used.

Randomized clinical trial comparing customized corneal crosslinking: epi-on in high oxygen and epi-off in room air for keratoconus.

PURPOSE: To compare clinical outcomes of customized transepithelial (epi-on) corneal crosslinking (CXL) in high oxygen and customized CXL with epithelial removal (epi-off) in room air for keratoconus (KC). SETTING: Umeå University Hospital, Umeå, Sweden. DESIGN: Prospective, randomized, single-masked, intraindividually comparing study. METHODS: 32 participants with bilateral progressive KC were treated with bilateral customized topography-guided CXL, 30 mW/cm 2 ; 7.2 to 15 J/cm 2 and were randomized to epi-on in one eye (32 eyes) and epi-off in the fellow eye (32 eyes). Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), maximal keratometry (Kmax), subjective ocular discomfort, low-contrast visual acuities (LCVAs) at 10% and 2.5% contrast, ocular and anterior corneal wavefront aberrations, manifest refractive spherical equivalent, endothelial cell count (ECC), and adverse events were assessed through 24 months. RESULTS: Both treatments showed improvements at 24 months in UDVA; -0.16 ± 0.24 ( P < .001) and -0.13 ± 0.20 logMAR ( P = .006), respectively, CDVA; -0.10 ± 0.11 ( P < .001) and -0.10 ± 0.12 ( P = .001), Kmax; -1.74 ± 1.31 ( P < .001) and -1.72 ± 1.36 D ( P < .001). LCVA 10% improved for both protocols ( P < .001), but LCVA 2.5% improved for epi-on CXL only ( P = .001). ECC was unaltered, and no adverse events occurred. The epi-on eyes had significantly less discomfort symptoms during the whole first week posttreatment ( P < .05). CONCLUSIONS: High-oxygen customized epi-on CXL is a viable alternative to room air customized epi-off CXL, with faster improvements in CDVA and LCVA and less early ocular discomfort.

Ten-year trends of immediate sequential bilateral cataract surgery (ISBCS) as reflected in the Swedish National Cataract Register.

PURPOSE: To analyse trends of ISBCS reported to the Swedish National Cataract Register (NCR) over a 10-year period. METHODS: Since 2010 the NCR contains social security number of all individuals in the list of parameters reported to NCR after each cataract procedure. Bilateral surgeries were mapped out using social security numbers. When dates of both-eye surgeries are identical for an individual it is classified as an immediate sequential bilateral cataract surgery (ISBCS). This study includes all data reported during the period 1st of January 2010 to 31st of December 2019. During the study period 113 cataract surgery clinics affiliated to the NCR reported their data on consecutive cataract cases. RESULTS: For the whole period 54 194 ISBCS were reported. The total number of bilateral cataract extractions was 422 300. There was a significant trend of increasing ISBCS over time with linear regression (Beta = 1.75, p < 0.001). In ISBCS the occurrence of an ocular comorbidity decreased over time. The use of a capsular tension ring was significantly more common in ISBCS than in delayed sequential bilateral cataract surgery (DSBCS). All other measures taken during surgery were more common in DSBCS. The use of multifocal IOL was significantly more frequent in ISBCS compared to DSBCS (p < 0.001). CONCLUSIONS: The use of ISBCS has increased over the study period. The operated eyes have less risk factors than eyes going through a DSBCS, but both ocular comorbidities and surgical complications occur in ISBCS eyes.

Safety of an Intracameral Fixed Combination for Mydriasis and Intraocular Anaesthesia During Cataract Surgery.

Purpose: To compare the safety of a standardized, commercially available intracameral combination of mydriatics and anesthetic (ICMA) with a reference topical mydriatic regimen for cataract surgery. Patients and Methods: The safety results from two international, randomized, controlled clinical studies were combined to compare ICMA at the beginning of cataract surgery (ICMA group) to the reference topical mydriatic regimen (reference group). Data were collected on ocular and systemic adverse events, corneal and anterior chamber examination, endothelial cell density, retinal thickness and visual acuity. Analysis was performed on a pooled safety set from both studies, preoperatively and up to 1 month postoperatively. Results: 342 patients received ICMA and 318 the reference topical regimen. Ocular adverse events were reported in 17.0% of patients in the ICMA group and 18.6% in the reference group. No difference was shown between groups in endothelial cell density (2208 ± 498 cells/mm2 for ICMA group versus 2241 ± 513 cells/mm2 for the reference group; p=0.547) and retinal thickness (change from baseline less than 50 µm in 94.7% versus 95.0% of patients, respectively) at 1 month postoperatively. At 1-day post-surgery, less patients in the ICMA group had moderate or severe (Grades 2 and 3) superficial punctate corneal staining (3.9% versus 7.0% for the reference group; p=0.064). Postoperatively, some ocular symptoms were also less frequently reported in the ICMA group. Best-corrected visual acuity increased in 96.0% of patients in the ICMA group and 95.8% in the reference group at 1 month. Conclusion: ICMA injection at the beginning of cataract surgery was demonstrated to be safe and may also provide perioperative and postoperative advantages over the standard topical mydriatic regimen.

[2.6 million cataract surgeries: 31 years with the Swedish National Cataract Register 1992-2022]. / 2,6 miljoner kataraktoperationer.

This review summarizes data collected by the Swedish National Cataract Register (NCR), which by the end of 2022 contained data on more than 2.6 million cataract surgeries between 1992-2022. During these 31 years, the cataract surgery rate (CSR) rose from 3 700 to 14 407. The coverage of NCR is very high, including 93% of all cataract procedures in Sweden during the last decade. A clear trend is that the procedure is performed in eyes with increasingly high visual acuity. The proportion of patients with Snellen 0.5 or worse in the first eye at surgery has decreased from 88% in 2007 to 69% in 2022. Patient Reported Outcome Measures (PROM) have been registered with the Catquest-9SF questionnaire since 2008, demonstrating stable favorable outcomes. Surgical complications have decreased; endophthalmitis has decreased from 0.10% to below 0.02%, and posterior capsule rupture from 2.8% to 0.6%.

Thermographic analysis of the corneal surface in epi-on and epi-off corneal crosslinking for keratoconus.

PURPOSE: To analyse the temperature of the corneal surface in keratoconus during corneal customized crosslinking (CXL) with a preserved epithelium (epi-on) under oxygen flow, and epi-off CXL in room air, and to assess the effect of pre-heating the oxygen. METHODS: This masked, intra-individual comparing randomized study included 14 participants with bilateral progressive keratoconus treated with bilateral CXL: one eye with epi-on CXL under a flow of 2.5 L/min oxygen; the fellow eye with epi-off CXL in room air. In a second setting involving 12 healthy participants, room-tempered oxygen was flushed over one eye and oxygen pre-heated to 37°C over the fellow eye. The corneal surface temperature was assessed with infrared photography. RESULTS: A reduction in corneal surface temperature was seen from the pre-treatment application of topical riboflavin in the epi-off group (-1.1 ± 1.0°C, p < 0.001). The temperature increased during the first half of the CXL treatment in both groups (+0.7 ± 1.2°C, p = 0.041 for epi-on; +0.7 ± 0.9°C, p = 0.023 for epi-off CXL, respectively). In epi-on CXL an overall temperature increase was seen during the treatment (+0.8 ± 1.2°C, p = 0.016). In the second setting, pre-heating the oxygen rendered a surface temperature increase of +1.8 ± 0.2°C (p < 0.001). CONCLUSION: In epi-off CXL, the application of topical room-tempered riboflavin decreases the corneal surface temperature, likely due to increased evaporation. A slight temperature increase is seen during CXL with both epi-on and epi-off CXL, albeit far below the corneal safety limit. The corneal temperature can, however, be increased by applying pre-heated oxygen, a possible approach to modify or augment the treatment effect in CXL.

Cataract surgery in patients with uveitis: Data from the Swedish National Cataract Register.

PURPOSE: To investigate the surgical and pharmacological management and outcomes of patients with cataract and concurrent uveitis. METHODS: Data from the Swedish National Cataract Register, 2018-2019, were collected and analysed. Uveitic eyes were identified and eyes without uveitis were used as controls. Generalized estimating equations were used to adjust for intra-individual correlation. RESULTS: The study included 719 eyes with and 256 360 without uveitis. The mean age was 66.0 ± 13.5 (standard deviation [SD]) years in the uveitis group and 74.3 ± 8.7 years in the control group (p < 0.001). Surgery was associated with more intraoperative difficulties in eyes with uveitis (27.0%) than in control eyes (7.1%; p < 0.001). Posterior capsule rupture/zonular complications were registered in nine eyes with uveitis (1.3%) and in 1464 eyes without uveitis (0.6%; p = 0.02). Hydrophilic acrylic intraocular lenses (uveitis 3.6%, controls 1.2%) and subconjunctival steroids (uveitis 17.4%, controls 6.1%) were more frequently used in eyes with uveitis (p < 0.001). post-operative best-corrected visual acuity (BCVA) was 0.16 ± 0.38 logarithm of the minimum angle of resolution (logMAR, mean ± SD) in eyes with uveitis (n = 52) and 0.08 ± 0.20 in control eyes (n = 14 489; p = 0.008). CONCLUSION: In this large registry-based Swedish cohort study, the findings demonstrate that cataract surgery in patients with uveitis poses more challenges and requires special surgical precautions. Eyes with concurrent uveitis had worse BCVA prior to and following surgery. Despite the intraoperative challenges, the visual improvement was greater in the uveitic group.

Two point four million cataract surgeries: 30 years with the Swedish National Cataract Register, 1992-2021.

The present review summarizes data collected by the Swedish National Cataract Register (NCR), which by the end of 2021 contained data for more than 2.4 million cataract surgeries between 1992 and 2021. During these 30 years, the cataract surgery rate rose from 3700 to 12 800. The coverage of NCR is very high including 93% of all cataract procedures in Sweden between 2010 and 2021. Independently of demographic changes, the proportion of operations of patients age 60 to 79 has increased while the proportion of 80 to 90+ has decreased. The median visual acuity of the first eye planned for surgery was 0.1 decimal in 1992 and has increased to 0.5 decimal in 2021. Patient-reported outcome measures have been registered with the Catquest-9SF questionnaire since 2008, demonstrating intervention at an earlier stage, but consistently favorable outcomes. Surgical complications have decreased; endophthalmitis has decreased from 0.10% to below 0.02%, and posterior capsule rupture from 2.8% to 0.6%.

Development of machine learning models to predict posterior capsule rupture based on the EUREQUO registry.

PURPOSE: To evaluate the performance of different probabilistic classifiers to predict posterior capsule rupture (PCR) prior to cataract surgery. METHODS: Three probabilistic classifiers were constructed to estimate the probability of PCR: a Bayesian network (BN), logistic regression (LR) model, and multi-layer perceptron (MLP) network. The classifiers were trained on a sample of 2 853 376 surgeries reported to the European Registry of Quality Outcomes for Cataract and Refractive Surgery (EUREQUO) between 2008 and 2018. The performance of the classifiers was evaluated based on the area under the precision-recall curve (AUPRC) and compared to existing scoring models in the literature. Furthermore, direct risk factors for PCR were identified by analysing the independence structure of the BN. RESULTS: The MLP network predicted PCR overall the best (AUPRC 13.1 ± 0.41%), followed by the BN (AUPRC 8.05 ± 0.39%) and the LR model (AUPRC 7.31 ± 0.15%). Direct risk factors for PCR include preoperative best-corrected visual acuity (BCVA), year of surgery, operation type, anaesthesia, target refraction, other ocular comorbidities, white cataract, and corneal opacities. CONCLUSIONS: Our results suggest that the MLP network performs better than existing scoring models in the literature, despite a relatively low precision at high recall. Consequently, implementing the MLP network in clinical practice can potentially decrease the PCR rate.

Enhanced age-related cataract in copper-zinc superoxide dismutase null mice.

BACKGROUND: As the lens is constantly exposed to light and oxygen that generate harmful reactive oxygen species, the importance of the intracellular antioxidant enzyme copper-zinc superoxide dismutase for the protection against age-related cataract development was explored. METHODS: The development of lens opacities and the lens oxidative status were studied in different age groups of mice lacking copper-zinc superoxide dismutase and in wild-type mice. The lens opacities were quantified from lens photographs using digital image analysis. Thereafter, the lenses were homogenized and analysed regarding their contents of reduced glutathione and protein carbonyls suggestive of protein oxidation. RESULTS: The 18-week-old mice of both genotypes had clear lenses. At 1 year of age, the copper-zinc superoxide dismutase null mice had developed cortical lens opacities, whereas the wild-type mice did not show equivalent changes until 2 years of age. The lens contents of glutathione decreased only in the 2-year-old wild-type mice, whereas the carbonyls increased over time without any differences between the two genotypes. CONCLUSIONS: This study indicates that the lack of copper-zinc superoxide dismutase may accelerate age-related lens opacity development and that intracellular superoxide-derived oxidative stress may be damaging to the lens during ageing. Participation of the anti-oxidant enzyme copper-zinc superoxide dismutase in the protection against age-related cataract was thus suggested.