Lens Nuclear Density Research Articles

Pseudoexfoliative Syndrome in Cataract Surgery-A Quality Register Study and Health Economic Analysis in the Split-Dalmatia County, Croatia.

To investigate the impact of pseudoexfoliation (PEX) syndrome on intraoperative phacoemulsification (PHACO) parameters and assess the economic cost of PHACO surgery for cataracts in patients with and without PEX syndrome. This was a retrospective quality register study on 5889 patients (6236 eyes) who underwent PHACO cataract surgery in the Eye Clinic, Clinical Hospital Centre Split, Croatia, over a 7-year period (May 2015 to December 2022), in accordance with the Guidelines of the Helsinki Declaration and approval from the Research Ethics Committee of the University Hospital Centre Split, Croatia. Inclusion criteria were patients with either presenile or senile cataract or cataract related to PEX syndrome who undertook PHACO procedure by the same experienced surgeon using the same PHACO device (Infiniti Vision System, Alcon Laboratories, Inc., Fort Worth, TX, USA). Eyes were categorized according to PEX presence- (PEX group) or absence (Group without PEX). The following recorded data about intraoperative PHACO parameters were collected: Cumulative Dissipated Energy (CDE), Ultrasound total time, PHACO time, torsional time, aspiration time, estimated fluid used, and duration of the surgical procedure. In the economic analysis, all PHACO parameters were considered, with a specific focus on the duration of the surgical procedure, costs associated with additional medical materials and devices, complications during surgery, and surgery procedure Diagnosis-Related Group (DRG) codes. A total of 4535 cases were eligible for inclusion in the study, 278 (6.13%) were diagnosed with PEX and 4257 (93.87%) had no PEX. Significantly higher PHACO parameters were observed in the PEX group. Similarly, a statistically significant increase in the values of all PHACO parameters was observed with the increase in nuclear lens density. Intraoperative complications were more frequent in the PEX group. Zonular weakness requiring the use of a capsular tension ring (CTR) and posterior capsular rupture occurred 30 and 13 times more often, respectively, in the PEX group. The expected cost of the PHACO procedure was found to be 1.4 times higher in patients with PEX, compared to those without PEX, for all types of nuclear cataract. All PHACO parameters are significantly higher in patients with PEX. The costs associated with PHACO surgery for cataracts are greater for patients with PEX and are not covered by the present DRG codes, which highlights the need to accordingly adjust the DRGs for PHACO procedures in PEX patients, in order to maintain the quality of healthcare provided for these vulnerable patients.

Change in Subfoveal Choroidal Thickness following Cataract Surgery Imaged with Enhanced Depth Imaging Optical Coherence Tomography.

Due to its invasive nature, cataract surgery can lead to inflammatory processes in the posterior segment, which can result in prolonged recovery times, reduced functional outcomes, and late-onset complications. The aim of the current study was to identify wherever phacoemulsification parameters play a role in choroidal thickness change following cataract surgery. This prospective single-center study enrolled 31 patients (31 eyes) scheduled to undergo routine cataract surgery. Patients with previous ocular surgeries, pathologies or general disorders affecting vision were excluded. Patients were examined preoperatively, as well as 1, 4, and 12 weeks after surgery. Corrected distance visual acuity (CDVA), intraocular pressure (IOP) as well as cumulative dissipated energy (CDE), ultrasound time (UT), and fluids used during surgery were recorded. Subfoveal choroidal thickness was measured manually by two masked independent experts using enhanced depth imaging (EDI) optical coherence tomography (OCT). Furthermore, cataract density was automatically calculated using a custom MATLAB script and an anterior segment OCT. Subfoveal choroidal thickness increased significantly (p < 0.001, Student's paired sample t-test) and continuously during the 12-week-long follow-up period. Both the nuclear lens density and the improvement in CDVA correlated significantly with this increase (r = 0.413, p = 0.021 and r = 0.421, p = 0.018, respectively). Neither the CDE (r = 0.334, p = 0.071), the UT (r = 0.102, p = 0.629), the amount of fluid used (r = 0.237, p = 0.27) nor the decrease in IOP (r = - 0.197, p = 0.288) showed any significant correlation with the choroidal swelling. Cataract surgery leads to an increase in subfoveal choroidal thickness. While no statistically significant correlation to the phacoemulsification parameters could be established, this might be because of a selection bias due to the technological constraints of the OCT. Nevertheless, the choroid might play a central role in early- and late-onset complications.

Objective evaluation of changes in lens clarity after repeated injections of ranibizumab in patients with neovascular age-related macular degeneration.

To objectively evaluate changes in lens densitometry in eyes with neovascular age-related macular degeneration (n-AMD) treated with repeated intravitreal ranibizumab injections during a 12-month period and to compare the results with those in untreated healthy fellow eyes and healthy control eyes. In this prospective study, the 36 treated eyes and the 37 untreated fellow eyes of 38 patients with n-AMD and the 32 control eyes of 32 healthy individuals were analyzed. Lens densitometry was evaluated using the Scheimpflug imaging. All data in both groups regarding lens densitometry were recorded at baseline and 12months. The mean densitometry of zone 1 in the treated eyes of patients had increased significantly at 12months compared with the baseline (baseline: 9.3 ± 1.5, 12months: 11.9 ± 1.7, p = .004) and was significantly greater than those measurements in the fellow eyes (9.8 ± 1.6 p = .02) and control eyes (9.6 ± 1.9, p = .01) at 12months as well. There were no significant differences in terms of densitometry values between the fellow and control eyes at baseline and 12months (for all, p > .05). Our results objectively demonstrate early nuclear lens density changes using with Scheimpflug images in eyes with n-AMD that were treated with repeated ranibizumab injections for 12months.

Comparison of the IOLMaster 700 and the Pentacam in the Analysis of the Lens Nuclear Density Before the Cataract Surgery.

Purpose: To evaluate the difference of the lens nuclear density measured before and after mydriasis by using the IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany) and the Pentacam Scheimpflug imaging (Pentacam HR, Oculus Incorporation, Wetzlar, Germany) and investigate the relationship between the measurement data and the phacoemulsification parameters.Methods: Patients with age-related nuclear cataracts diagnosed on the slit-lamp examination were enrolled in the age range of 53–76 years. No patient had a history of ocular surgery, laser treatment, or general disorders affecting vision. The mean optical density (OD) was measured by the IOLMaster 700 by using the Image-Pro® Plus software before and after mydriasis. The Pentacam nucleus densitometry (PND) was obtained automatically from the Pentacam Scheimpflug imaging and compared with OD. The correlation between OD and effective phacoemulsification time (EPT), PND, and EPT were analyzed, respectively.Results: In this study, 53 eyes of 52 patients were evaluated. Before and after mydriasis, the mean OD values were 64.34 ± 23.31 and 63.81 ± 23.21 pixel units, respectively; the mean PND values were 28.51 ± 11.42 and 25.41 ± 11.31, respectively; and the mean EPT value was 6.24 ± 3.49. The Bland–Altman analysis showed that the lens nuclear densities of the two devices were highly consistent. There was no significant difference in the OD values (t = 0.455, p > 0.05) before and after mydriasis, but the difference has existed in the PND values (t = 2.509, p < 0.05). The OD and PND values were positively correlated with EPT before and after mydriasis (rOD−Before = 0.604, rOD−After = 0.593, rPND−Before = 0.701, and rPND−After = 0.891, p < 0.01).Conclusion: The combination of the IOLMaster 700 and the Image-Pro® Plus software can quantitatively evaluate the degree of the cataract lens opacification. It has good consistency with the Pentacam and is positively correlated with the phacoemulsification parameters. It is expected to become a new method to predict the phacoemulsification parameters before and during cataract surgery.

Relationship of Objective Metrics for Quantifying Age-related Nuclear Cataracts with Visual Acuity and Phacodynamics

IntroductIon: An appropriate evaluation cataract degree is essential for deciding to proceed with surgery. Our purpose was to study the relationship between objective metrics for quantifying age-related nuclear cataracts with visual impairment and phacodynamics parameters. Methods: Thirty eyes (30 patients) with age-related nuclear cataract were submitted to phacoemulsification. The average lens density (0 to 100) was evaluated by using a rotating Scheimpflug system (Pentacam HR, Oculus, Wetzlar, Germany) and the nuclear opalescence (NO) score was subjectively assessed using the Lens Opacities Classification System III (LOCS III). This different parameters were correlated with preoperative corrected distance visual acuity (CDVA) and cumulative dissipated energy (CDE). Results: The preoperative CDVA was correlated with the Scheimpflug-measured lens nuclear density value (r=0.617, p<0.01). The CDE was posi-tively correlated with the Scheimpflug-derived average density variable (r=0.681 p<0.01) than with LOCS III NO (r=0.661, p<0.01). Conclusion: The Scheimpflug-measured average density was correlated with subjective lens grading and preoperative CDVA. This metric also presented the highest positive correlation with phacodynamics.

Objective quantification of lens nuclear opacities using swept-source anterior segment optical coherence tomography

Background/aimsThe primary objective is to quantify the lens nuclear opacity using swept-source anterior segment optical coherence tomography (SS-ASOCT) and to evaluate its correlations with Lens Opacities Classification System III (LOCS-III)...

Wavefront aberrations and retinal image quality in different lenticular opacity types and densities

To investigate wavefront aberrations in the entire eye and in the internal optics (lens) and retinal image qualities according to different lenticular opacity types and densities. Forty-one eyes with nuclear cataract, 33 eyes with cortical cataract, and 29 eyes with posterior subcapsular cataract were examined. In each group, wavefront aberrations in the entire eye and in the internal optics and retinal image quality were measured using a raytracing aberrometer. Eyes with cortical cataracts showed significantly higher coma-like aberrations compared to the other two groups in both entire eye and internal optic aberrations (P = 0.012 and P = 0.007, respectively). Eyes with nuclear cataract had lower spherical-like aberrations than the other two groups in both entire eye and internal optics aberrations (P < 0.001 and P < 0.001, respectively). In the nuclear cataract group, nuclear lens density was negatively correlated with internal spherical aberrations (r = −0.527, P = 0.005). Wavefront technology is useful for objective and quantitative analysis of retinal image quality deterioration in eyes with different early lenticular opacity types and densities. Understanding the wavefront optical properties of different crystalline lens opacities may help ophthalmic surgeons determine the optimal time to perform cataract surgery.

Correlations of Objective Metrics for Quantifying Dysfunctional Lens Syndrome With Visual Acuity and Phacodynamics.

To study the relationship between objective metrics for quantifying crystalline lens dysfunction with visual impairment and phacodynamics parameters in age-related nuclear cataracts. A total of 51 eyes (34 patients) with age-related nuclear cataract had phacoemulsification. The Dysfunctional Lens Index (0 to 10 points) was measured by a ray-tracing aberrometry (iTrace Visual Function Analyzer; Tracey Technologies, Houston, TX). The average lens density (0 to 100) was evaluated using a rotating Scheimpflug system (Pentacam HR; Oculus Optikgeräte GmbH, Wetzlar, Germany), and the nuclear opalescence score was subjectively assessed using the Lens Opacities Classification System III (LOCS III). The different parameters for evaluating crystalline lens dysfunction were correlated with preoperative corrected distance visual acuity (CDVA) and cumulative dissipated energy (CDE). There was a negative linear correlation between the Dysfunctional Lens Index and the LOCS III nuclear opalescence and Scheimpflug-measured average density (r =-0.728 and r = -0.771, respectively; both P < .01). The preoperative CDVA was correlated with the Scheimpflug-measured lens nuclear density value (r = 0.612, P < .01) and Dysfunctional Lens Index score A (r =-0.670, P < .01). The CDE was more strongly correlated with Dysfunctional Lens Index and Scheimpflug-derived average density (r =-0.744 and r = 0.700, respectively; both P < .01) than with LOCS III nuclear opalescence (r = 0.646, P < .01). The Dysfunctional Lens Index was correlated with the Scheimpflug-measured average density, subjective lens grading, and preoperative CDVA. This metric also presented the highest correlation with phacodynamics. Correlation with other clinical measures related to visual quality and impairment are still needed. [J Cataract Refract Surg. 2017;33(2):79-83.].

Quantitative Analysis of Lens Nuclear Density Using Optical Coherence Tomography (OCT) with a Liquid Optics Interface: Correlation between OCT Images and LOCS III Grading.

Purpose. To quantify whole lens and nuclear lens densities using anterior-segment optical coherence tomography (OCT) with a liquid optics interface and evaluate their correlation with Lens Opacities Classification System III (LOCS III) lens grading and corrected distance visual acuity (BCVA). Methods. OCT images of the whole lens and lens nucleus of eyes with age-related nuclear cataract were analyzed using ImageJ software. The lens grade and nuclear density were represented in pixel intensity units (PIU) and correlations between PIU, BCVA, and LOCS III were assessed. Results. Forty-seven eyes were analyzed. The mean whole lens and lens nuclear densities were 26.99 ± 5.23 and 19.43 ± 6.15 PIU, respectively. A positive linear correlation was observed between lens opacities (R 2 = 0.187, p < 0.01) and nuclear density (R 2 = 0.316, p < 0.01) obtained from OCT images and LOCS III. Preoperative BCVA and LOCS III were also positively correlated (R 2 = 0.454, p < 0.01). Conclusions. Whole lens and lens nuclear densities obtained from OCT correlated with LOCS III. Nuclear density showed a higher positive correlation with LOCS III than whole lens density. OCT with a liquid optics interface is a potential quantitative method for lens grading and can aid in monitoring and managing age-related cataracts.

Measurement of lens density using Scheimpflug imaging system as a screening test in the field of health examination for age-related cataract

PurposeTo assess Pentacam (Oculus, Wetzlar, Germany) Scheimpflug quantitative images in evaluating lens density and providing objective measurements to suggest optimal time of cataract surgery in the field of health examination.MethodsTwo...

Use of Nonmydriatic Spectral-Domain Optical Coherence Tomography for Diagnosing Diabetic Macular Edema

To evaluate the accuracy of 3 spectral-domain (SD) optical coherence tomography (OCT) devices (Topcon 3D-1000 [Topcon]; Cirrus HD [Carl Zeiss Meditec, Inc], and Spectralis OCT [Heidelberg Engineering]) before and after mydriasis for the diagnosis of diabetic macular edema. Cross-sectional study. Sixty-two eyes of 62 consecutive patients with diabetes without recent loss of vision referred for retinal control were assessed. Two scans were performed for each SD OCT instrument. Central retinal thickness was measured before and after pupil dilation. Pupil dynamic was studied using pMetrics pupillometer (iVIS Technologies), and lens opacity was measured by Pentacam densitometry (Oculus). The diagnostic accuracy of SD OCT devices was assessed by sensitivity, specificity, and area under the receiver operating characteristic curve. Logistic regression analysis was used to assess the effect of pupil size and lens opacity on the reliability of SD OCT in the acquisition of adequate images. The area under the receiver operating characteristic curve for the Topcon 3D OCT device was 0.84, that for the Cirrus HD OCT device was 0.93, and that for the Spectralis OCT device was 0.91. Significant differences in area under the receiver operating characteristic curve before and after pupillary dilatation were not found. Sensitivity and specificity associated with the cutoff value for the best performance were 82% and 74% for the Topcon 3D OCT device, 90% and 87% for the Cirrus HD OCT device, and 90% and 84% for the Spectralis OCT device, respectively. The Topcon 3D OCT device had an 11.3% segmentation algorithm failure rate for the central millimeter of the fovea, and the nuclear lens density was significantly greater in these eyes than in those without failure (17.1 ± 1.1 mm vs 10.4 ± 0.2 mm; P < .05). SD OCT is a useful tool to detect and to measure diabetic macular edema without the need for pupil dilatation.

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

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. 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. 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. 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.

Clinical application of a Scheimpflug system for lens density measurements in phacoemulsification

To evaluate the relationship between lens density measured using the Pentacam Scheimpflug system and phacodynamics (phacoemulsification time, phacoemulsification energy, and balanced salt solution [BSS] use) in patients with age-related nuclear cataract. Department of Ophthalmology and Visual Science, Kangnam St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea. This prospective observer-masked study was of eyes with age-related nuclear cataract. Objective lens density (0 to 100 points) was determined using the Scheimpflug system. Subjective grading was by the Lens Opacities Classification System III (LOCS III). The correlations between lens density values and phacoemulsification time, phacoemulsification energy, and BSS use were analyzed prospectively. Fifty-three patients (60 eyes) were evaluated. The mean Scheimpflug-measured lens nuclear density was 14.71 +/- 6.12 (SD). There was a positive linear correlation between the Scheimpflug-measured lens nuclear density and the LOCS III grading scores for nuclear opalescence (NO) and nuclear color (NC) (r = 0.734 and 0.719, respectively; both P<.05). The Scheimpflug-measured lens nuclear density correlated with torsional amplitude, time, and cumulated dissipated energy (CDE) (P<.05), but not with BSS use (P = .195). The CDE was more strongly correlated with Scheimpflug-measured lens nuclear density (r = 0.797) than with LOCS III NO or NC scores (r = 0.614 and r = 0.637, respectively). Scheimpflug-measured lens nuclear density correlated with phacoemulsification time and energy. The Scheimpflug system enabled quantitative cataract grading and may help predict phacodynamics in cataract surgery.

Correlation of Nuclear Cataract Lens Density Using Scheimpflug Images with Lens Opacities Classification System III and Visual Function

To calculate the average lens density (ALD) and nuclear lens density (NLD) using Scheimpflug images and to determine their correlation with logarithmic minimal angle resolution (logMAR) best-corrected visual acuity (BCVA), contrast sensitivity (CS), and lens grading based on the Lens Opacities Classification System (LOCS) III. Cross-sectional observational study. One hundred ten patients with age-related nuclear cataract. The logMAR BCVA was recorded using Early Treatment Diabetic Retinopathy Study charts and photopic contrast-sensitivity using CSV-1000LV (Vector Vision, Greeneville, OH). Fifty Scheimpflug images (Pentacam, Oculus, Germany) covering 360 degrees of the lens were obtained for 1 eye of each patient after dilation. All Scheimpflug images were exported to ImageJ software (NIH, Bethesda, MD) for analysis wherein the ALD and NLD (using a mask applied to the lens nuclear area) were calculated in pixel-intensity units. Repeatability was determined using coefficient of variation (CoV) and intraclass correlation coefficient (ICC). Lens opacity on slit-lamp images was graded using LOCS III for nuclear opalescence (NO) and nuclear color (NC). We evaluated ALD and NLD on Scheimpflug images and their correlation with NO and NC LOCS III grading, BCVA, and photopic CS. The ICC for ALD and NLD were 0.983 and 0.99, respectively; the CoV were 3.92+/-1.76% and 2.57+/-0.74%, respectively. The ALD correlated with NO (r = .774; P<0.001), NC (r = .732; P<0.001), BCVA (r = 0.696; P<0.001), and CS at 3 cycles per degree CPD (P = 0.011), 6, 12, and 18 CPD (P<0.001). The NLD correlated with NO (r = .859; P<0.001), NC (r = .81; P<0.001), BCVA (r = .760; P<0.001), CS at 3 CPD (P = 0.002), 6, 12, and 18 CPD (P<0.001). The NLD had a significantly stronger correlation with BCVA (P<0.05), NO (P<0.01), NC (P<0.01), and CS at 6 CPD (P<0.01) and 12 CPD (P<0.005) compared with ALD. Repeatable 360 degrees lens density measurements were obtained using Scheimpflug imaging. A stronger correlation was observed between NLD and LOCS III grading, BCVA, and photopic CS than with ALD. The NLD is an objective and repeatable method for assessment of lens density, which could be helpful in longitudinal studies monitoring nuclear cataracts.

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...

Dietary Linolenic Acid Intake Is Positively Associated with Five-Year Change in Eye Lens Nuclear Density

Objective: Dietary fat may affect lens cell membrane composition and function, which are related to age-related cataract. The present study was designed to examine the associations between dietary fat and the change in nuclear lens opacification over five years.Methods: Women aged 52 to 73 years without previously diagnosed cancer, diabetes and cataracts from the Boston, Massachusetts area were selected from the Nurses’ Health Study cohort. Four hundred forty women participated in a baseline (1993–95) and a follow-up (1998–2000) eye examination. Intakes of total fat and selected fatty acids were calculated as the average intake from five food frequency questionnaires that were collected between 1980 and baseline. Change in the degree of nuclear density (opacification) was characterized by the difference between baseline and follow-up in pixel density at the central clear zone in the Scheimpflug slit image of the lens.Results: Intake of alpha-linolenic acid (ALA) was positively associated with change in nuclear density. The geometric mean nuclear density change was 16% greater in the highest quartile category of ALA intake than in the lowest quartile category (P for trend = 0.05). For women in the high tertile category of baseline nuclear lens opacification, the geometric mean change in the highest quartile category of ALA acid intake was 70% higher than the change in the lowest quartile category (P for trend = 0.01). There were no significant associations between other dietary fats and change in nuclear density.Conclusion: Higher ALA intake was associated with a greater age-related change in lens nuclear density.

Long-term Nutrient Intake and 5-Year Change in Nuclear Lens Opacities

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. 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). 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). 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.

Contrast sensitivity in patients with nuclear cataracts.

Spatial contrast sensitivity and lens density were measured in 30 subjects (18 patients with pure nuclear cataracts and 12 age-matched controls). Contrast sensitivity was assessed using two techniques: a conventional monitor method in which gratings were viewed through the cataract (overall spatial contrast sensitivity) and a laser interferometer method in which gratings were formed directly on the retina (interferometric spatial contrast sensitivity), thus reducing the effect of an opaque lens on grating contrast. The degree of lens nuclear opacity was measured by assessing the density of Zeiss Scheimpflug slit-lamp video camera images. A contrast sensitivity loss was found by using both methods; this reduction reached statistical significance only when monitor stimuli were used. There was a significant correlation between lens nuclear density and sensitivity loss at spatial frequencies from 4 to 16 cycles/degree (r = .56 to .79 and P less than .05 to less than .001). A correlation coefficient of .82 (P less than .001) characterized the relationship between visual acuity (log of the minimal angle of resolution) and lens density. Nuclear lens opacity significantly affects contrast sensitivity; pure nuclear cataracts produce spatial visual losses at intermediate and high spatial frequencies.