Quantitating cataract and nuclear brunescence, the Harvard and LOCS systems

The effect of aging on the eccentricity dependency of orientation anisotropy of perceptual surround suppression

The features of perceptual surround suppression vary with eccentricity, such that the suppression strength is increased for horizontally oriented stimuli relative to other orientations near the fovea, but is strongest for radially oriented stimuli more peripherally. Perceptual suppression also varies with age, which has been well-studied for central fixation. However, only limited data are available regarding perceptual suppression in older adults for nonfoveal vision, and none of those studies have taken orientation biases of contrast sensitivity into account. Here, we explored the effects of older age on the eccentricity dependency of orientation biases of perceptual suppression. We found increased perceptual suppression in older adults at both 6° and 15° eccentricities relative to younger adults. A main effect of the horizontal orientation bias was found at 6° and a main effect of the radial orientation bias was found at 15° in both groups. In summary, perceptual surround suppression of contrast is stronger for older adults compared with younger adults at 6° and 15° eccentricities, but retinotopic orientation anisotropies are maintained with age. This study provides new insight into parafoveal visual perception in older adults, which may be particularly important to understand the visual experience of those who depend on nonfoveal vision owing to common age-related eye diseases.

Phakic intraocular lenses: An overview

Phakic intraocular lenses (pIOLs) are a common solution for the surgical correction of high myopia and myopia in thin corneas. Global trends result in increasing rates of patients with high myopia which will result in increased rates of pIOL implantation. Three types of lenses can be distinguished: anterior chamber angle-supported, anterior chamber iris-fixated, and posterior chamber phakic IOLs. The efficacy of phakic intraocular lenses is generally very good, but pIOLs have undergone many changes over the years to improve the safety profile and decrease pIOL-related complications such as endothelial cell loss, corneal decompensation and cataract formation. This article describes the efficacy and safety profiles of the most recent pIOLs, as well as suggests gaps of knowledge that are deserve additional research to optimize the results of pIOLs.

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

PURPOSE

To study the relationship between objective metrics for quantifying crystalline lens dysfunction with visual impairment and phacodynamics parameters in age-related nuclear cataracts.

METHODS

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).

RESULTS

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).

CONCLUSIONS

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.].

Clinical results after microincision biaxial cataract surgery and implantation of an Incise intraocular lens

PURPOSE

To evaluate clinical outcomes after uncomplicated microincision biaxial cataract surgery and implantation of Incise intraocular lens (IOL).

METHODS

This study included 47 eyes of 29 patients (mean age 62.2 ± 8.6 years), who underwent 1.4-mm biaxial cataract surgery with implantation of the Incise IOL (Bausch and Lomb). At third month, surgically induced astigmatism (SIA) was calculated. Three, 6 and 12 months postoperatively, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corrected near visual acuity (CNVA) LogMAR ETDRS, spherical equivalent refraction (SER), photopic distance corrected contrast sensitivity (CS) with and without glare (85 cd/m²) (CSV-1000) were assessed. One year after surgery, late complications were assessed and subjects were questioned for subjective symptoms.

RESULTS

Mean of SIA was equal 0.29 ± 0.16 D. Three months postoperatively: mean UDVA improved from 0.83 to 0.04 (p < 0.001), CDVA from 0.58 to -0.05 (p < 0.001) and CNVA from 0.58 to -0.02 (p < 0.001) and all were stable during 1-year follow-up. Three months postoperatively, the mean SER was equal 0.07 ± 0.61 D and was within ±0.5 D in 79%, and within 1 D in 88% of eyes. During follow-up period, corrected CS with and without glare for distance was found to be within normal limits. The only late complication was posterior capsule opacification (PCO). Subjective quality of vision was very high; none of patients complained about glare.

CONCLUSIONS

Biaxial cataract surgery with implantation of the Incise IOL provided excellent clinical outcomes by minimizing SIA, stable refraction and low incidence of PCO.

[Clinical, morphological and molecular biological characteristics of the aging eye]

BACKGROUND

The physiological aging of the eye is associated with loss of visual function. Age-related changes of the eye can result in ophthalmological diseases. The aim of this article is to display morphological, histological and molecular biological alterations of the aging eye.

MATERIAL AND METHODS

A web-based search and review of the literature for aging of the visual system including cornea, lens, vitreous humor, retina, retinal pigment epithelium (RPE), choroidea and optic nerve were carried out. The most important results related to morphological, histological and molecular biological changes are summarized.

RESULTS

Age-related, morphological alterations can be found in preretinal structures, e. g. cornea, lens and vitreous humor, as well as neuronal structures, such as the retina. In addition to negligible clinical signs of the aging eye, there are clinically relevant changes which can develop into pathological ophthalmological diseases. These transitions from age-related alterations to relevant ophthalmological diseases, e. g. age-related macular degeneration and glaucoma are continuous.

CONCLUSION

An understanding of aging could provide predictive factors to detect the conversion of physiological aging into pathological conditions. The derivation of physiological markers or new approaches to detection and treatment of disease-related entities associated with the risk factor aging are desirable. Translational approaches in clinical and basic science are necessary to provide new therapeutic options for relevant ophthalmological diseases in the future.

Sub-Tenon injection of 2% lidocaine prevents intra-operative floppy iris syndrome (IFIS) in male patients taking oral α-adrenergic antagonists

PURPOSE

  To compare 2% sub-Tenon and 1% intra-cameral lidocaine for cataract surgery in relation to the incidence and severity of IFIS. Prospective randomized clinical study.

METHODS

  From 81 eligible, we included 71 men aged from 59 to 90 years (mean 76.5 ± 6.8) undergoing routine cataract surgery and taking oral α-adrenergic antagonists, for urological reasons, for more than 1 year. Following randomization 34 men, aged from 62 to 90 years (mean 77.4 ± 8.1) received sub-Tenon injection of 2.5 ml of 2% lidocaine and the remaining 37 men aged from 59 to 89 years (mean 75.2 ± 7.2) received 1% preservative free intra-cameral lidocaine. Outcome measures were the incidence of IFIS, severity of intra-operative pupillary constriction and iris prolapse.

RESULTS

  Intra-operative floppy iris syndrome (IFIS) was noted in 3 of 34 patients (8.8%) receiving sub-Tenon lidocaine and in 18 of 37 patients (48.6%) receiving intra-cameral lidocaine (p = 0.00). Severe IFIS was observed only in 3 of 37 patients (8.1%) receiving intra-cameral lidocaine. Pupil diameter at the end of surgery was 4.37 ± 1.07 mm in the sub-Tenon lidocaine group and 4.02 ± 1.06 mm in the intra-cameral lidocaine group (p = 0.00). Iris prolapse was noted in two cases in the sub-Tenon lidocaine group and in 10 cases in the intra-cameral lidocaine group (p = 0.00). Twenty-five patients were receiving tamsulosin. The incidence of IFIS in tamsulosin subgroup was 76.9% (10 of 13 patients) in the intra-cameral lidocaine group and 16.6% (2 of 12 patients) in the sub-Tenon lidocaine group (p = 0.00).

CONCLUSION

  Sub-Tenon lidocaine reduces significantly the incidence of IFIS in patients taking oral α-adrenergic inhibitors as compared with intra-cameral lidocaine.

Improvement of functional visual acuity after cataract surgery in patients with good pre- and postoperative spectacle-corrected visual acuity

PURPOSE

To report the changes in functional visual acuity in cataract surgery patients with good pre- and postoperative visual acuity.

METHODS

Functional visual acuity was evaluated in 13 eyes of 10 patients before and 1 month after phacoemulsification with implantation of acrylic intraocular lenses. Pre- and postoperative best spectacle-corrected visual acuities (BSCVA) were better than 20/25 in all patients. Low contrast visual acuity and Schirmer tests were also performed before and after surgery.

RESULTS

Mean pre- and postoperative logMAR BSCVA were -0.02 +/- 0.06 and -0.05 +/- 0.04, respectively (P > .05). Mean preoperative logMAR functional visual acuity improved from 0.29 +/- 0.17 to 0.092 +/- 0.13 postoperatively (P < .05). The visual maintenance ratio in functional visual acuity and low contrast visual acuity also improved significantly after cataract surgery (P < .05).

CONCLUSIONS

Measurement of functional visual acuity seems to be useful in the evaluation of timing of surgery, visual quality, and changes in kinetic vision after phacoemulsification surgery.

LOCS III examination at the slit lamp, do settings matter?

PURPOSE

To explore whether slit lamp settings may influence measurements made with the LOCS III grading system. The following were tested using a total of 221 subjects: 1. Test-retest variability (with and without the neutral density filter). 2. Readings with and then without the neutral density filter. 3. Readings with maximum and minimum illumination (filter and rheostat). 4. Examinations with different slit beam width. 5. Light output from 10 slit lamps (Haag-Streit 900BM) was measured using a lightmeter.

RESULTS

The 95% limits of agreement (test-retest examination) for nuclear opacity (NO), nuclear colour (NC), cortical opacity (C), and posterior subcapsular lens opacity (P) were 0.66, 0.60, 0.62 and 0.39, respectively, using standard settings. Corresponding results with the neutral density filter were similar. Examinations performed with and without the neutral density filter showed that the 95% limits of agreement increased by a factor of at least 1.7 compared with test retest data (NO and NC) and 2.2 for (C and P) (p < 0.001 (f test)). Maximum vs. minimum brightness settings increased variability by a factor of at least 2.1 (NO and NC) and 3 (C and P) (p < 0.001 (f test)). Changing beam width measurements produced a significant systematic measurement bias of 0.3 for NO and 0.4 for NC (P < 0.01 (t test)), a wider beam giving a higher score. Individual slit lamps may vary by a factor of four in their light output levels for apparently identical settings. The range of illumination produced by a slit lamp is 46-fold.

CONCLUSIONS

For nuclear opacity and nuclear colour measurements, changing settings between examinations increases variability without evidence of systematic bias. However, using a thicker slit beam induced a systematic bias. For cortical and posterior subcapsular lens opacity, varying the illumination had more marked effects on reproducibility without a systematic bias.

Vitamin C-mediated Maillard reaction in the lens probed in a transgenic-mouse model

Aging human lens crystallins are progressively modified by yellow glycation, oxidation, and cross-linked carbonyl compounds that have deleterious properties on protein structure and stability. In order to test the hypothesis that some of these compounds originate from oxidized vitamin C, we have overexpressed the human vitamin C transporter 2 (hSCVT2) in the mouse lens. We find that levels of ascorbic and dehydroascorbic acid are highly elevated compared to the wild type and that the lenses have accumulated yellow color and advanced Maillard reaction products identical with those of the human lens. Treatment of the mice with nucleophilic inhibitors can slow down the process, opening new avenues for the pharmacological prevention of senile cataractogenesis.

Automated, computerized, feature-based phenotype analysis of slit lamp images of the mouse lens

Longitudinal studies of a variety of transgenic mouse models for lens development can create substantial challenges in database management and analysis. We report a novel, automated, feature-based informatics approach to screening lens phenotypes in a large database of slit lamp images. Digital slit lamp images of normal and abnormal lenses in eyes of wild type (wt), SC1 null and SPARC null transgenic mice were recorded for quantitative evaluation of their structural phenotype. The images were processed to improve the contrast of structural features that corresponded to rings of opacity and fluctuations in scattering intensity in the lenses. Measurable attributes were assigned to the features in the lens images and given as an output vector of 46 dimensions. Characteristic patterns were correlated with the structural phenotype of each mutant and wt lens and a statistical fit for each phenotype was defined. The genotype was identified correctly in nearly 85% of the slit lamp images on the basis of an automated computer analysis of the lens structural phenotype. The automated computer algorithm has the potential to evaluate a large database of slit lamp images and distinguish mouse genotypes on the basis of lens phenotypes objectively using a neural network analysis of the structural features observed in the slit lamp images. The neural network approach is a promising technology for objective evaluation of genotype/phenotype relationships based on structural features and light scattering in lenses. Further improvements in the automated method can be expected to simplify and increase the accuracy and efficiency of the feature based analysis of structural phenotypes linked to genetic variation.

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.

Vitamin C mediates chemical aging of lens crystallins by the Maillard reaction in a humanized mouse model

Senile cataracts are associated with progressive oxidation, fragmentation, cross-linking, insolubilization, and yellow pigmentation of lens crystallins. We hypothesized that the Maillard reaction, which leads browning and aroma development during the baking of foods, would occur between the lens proteins and the highly reactive oxidation products of vitamin C. To test this hypothesis, we engineered a mouse that selectively overexpresses the human vitamin C transporter SVCT2 in the lens. Consequently, lenticular levels of vitamin C and its oxidation products were 5- to 15-fold elevated, resulting in a highly compressed aging process and accelerated formation of several protein-bound advanced Maillard reaction products identical with those of aging human lens proteins. These data strongly implicate vitamin C in lens crystallin aging and may serve as a model for protein aging in other tissues particularly rich in vitamin C, such as the hippocampal neurons and the adrenal gland. The hSVCT2 mouse is expected to facilitate the search for drugs that inhibit damage by vitamin C oxidation products.

Overall adherence to the dietary guidelines for americans is associated with reduced prevalence of early age-related nuclear lens opacities in women

Few studies have examined the efficacy of the Dietary Guidelines for Americans in the prevention of age-related chronic disease, such as age-related cataract. We examined whether adherence to the Guidelines was associated with a lower prevalence of age-related nuclear lens opacities in women. Eye exams were conducted in 479 Nurses' Health Study participants aged 52 to 73 y without previously diagnosed cataract or diabetes living in the Boston, MA area. Four FFQs, collected during a 9- to 11-y period before evaluation of lens status, were used to define diet quality according to the following: 1) daily number of servings of fruits, vegetables, and whole grains; 2) Recommended Foods Score (RFS); and 3) Healthy Eating Index (HEI). Nuclear opacities were defined as scores >/= 2.5 using the Lens Opacification Classification System III. After adjusting for age, smoking, and other risk factors, women in the highest quartile category of HEI scores were significantly less likely to have nuclear opacities than those in the lowest category [odds ratio (OR) = 0.47; 95% CI: 0.26-0.84]. This association appeared to be stronger among nonusers of supplemental vitamin C (OR = 0.23; 95% CI: 0.10-0.52). Decreased prevalence odds of nuclear opacities were also observed with high intake of fruit (OR = 0.58; 95% CI: 0.32-1.05) and whole grains (OR = 0.64; 95% CI: 0.36-1.15). These results suggest that overall compliance with the Dietary Guidelines, as measured by the HEI, protects against nuclear opacities.

Weight status, abdominal adiposity, diabetes, and early age-related lens opacities

BACKGROUND

The association between weight status and the risk of lens opacities has received little attention.

OBJECTIVE

We examined the cross-sectional relations of body mass index (BMI; in kg/m(2)), waist circumference, and diabetes with the presence of age-related lens opacities.

DESIGN

Eye examinations were conducted in 466 Boston-area women aged 53-73 y who were without previously diagnosed cataracts and were part of the Nurses' Health Study cohort. Weight, height, waist, and hip measurements were obtained by self-report. Lens status was evaluated by using the Lens Opacification Classification System III (LOCS III). BMI and waist circumference were used as measures of overweight and abdominal adiposity, respectively. Nuclear, cortical, and posterior subcapsular (PSC) opacities were defined as LOCS III scores > or = 2.5, > or = 1.0, and > or = 0.5, respectively. Diabetes was defined as a history of type 2 diabetes or as a fasting plasma glucose concentration > or = 7.0 mmol/L.

RESULTS

Women with diabetes were significantly more likely to have PSC opacities [odds ratio (OR): 4.1; 95% CI: 1.8, 9.4] than were women with fasting plasma glucose concentrations < 6.1 mmol/L. Women with a BMI > or = 30 had a higher prevalence of PSC opacities than did women with a BMI < 25 (OR: 2.5; 1.2, 5.2), and women with a waist circumference > or = 89 cm had a higher prevalence of PSC opacities than did those with a waist circumference < 80 cm (OR: 2.3; 1.0, 5.2). Diabetes and measures of adiposity were unrelated to the prevalence of cortical and nuclear opacities.

CONCLUSIONS

Diabetes is a strong risk factor for PSC opacities, and overweight and abdominal adiposity may be risk factors for PSC opacities.

The relationship between nuclear colour and opalescence on the LOCSIII scale and physical characteristics of cataract nuclei

PURPOSE

To evaluate the compression characteristics of the human lens nucleocortex in relation to its LOCSIII clinical grading.

METHODS

Sixteen subjects undergoing planned extracapsular cataract surgery had pre-operative slit-lamp examination and assessment of cataract LOCSIII grade followed by postoperative in vitro evaluation of the nucleus with measurement of 'linear compressibility' by a purpose-designed caliper incorporating a strain gauge, enabling the derivation of a graph of nuclear compression (D (mm) against applied force (F (N)).

RESULTS

Nuclear colour correlates with the force required to compress a lens to 75% of its original depth (F75) (R = 0.625, P = 0.017). Nuclear opalescence correlates with the force required to compress a lens to 75% of its original depth (R = 0.651, P = 0.012) and inversely with linear compressibility (DeltaD/DeltaF, the slope of the graph of nuclear compression against applied force) (R = -0.610, P = 0.014). F75 is a direct and linear compressibility is an inverse related parameter of lens nucleus 'hardness'.

CONCLUSION

A new instrument is described which allows measurement of 'hardness'-related compression characteristics of the human cataract in vitro. There is a relationship between the LOCSIII clinical classification of nuclear cataracts and mechanical compression characteristics of the cataractous lens. LOCSIII classification may aid the preoperative planning of an appropriate surgical approach to an individual cataract.

Postmenopausal hormone use and lens opacities

PURPOSE

Women are at higher risk for age-related cataract than men, and it has been hypothesized that this difference is due in part to gender-related hormonal differences.

METHODS

We investigated the association between postmenopausal hormone use and lens opacities in a population of 480 postmenopausal women from the Nurses' Health Study for whom we had prospectively collected exposure data. Participants received standardized eye exams; the Lens Opacity Classification System III (LOCS III) was used to measure the degree of opacification.

RESULTS

A total of 342 women had some opacity in one or both eyes. Overall, we did not observe a significant association between current hormone use and presence of any type of opacity (compared to never users, multivariate relative risk: 0.85; 95% confidence interval (CI): 0.54-1.34). In ordinal logistic regression compared to never users, current hormone users had multivariate relative risks of cortical opacities of 0.80 (95% CI: 0.54-1.19) and for past users the relative risk was 0.76 (95% CI: 0.48-1.22). For nuclear opacities, the comparable relative risk for current use of hormones was 0.77 (95% CI: 0.52-1.13), and for past use the relative risk was 1.48 (95% CI: 0.92-2.34). Current use of estrogen-only preparations was associated with a 49% decreased risk of nuclear opacities compared to never use (multivariate relative risk 0.51, 95% CI: 0.29-0.89).

CONCLUSIONS

While the overall findings are null, they do not exclude the possibility of a protective effect, particularly among current estrogen users.

Space radiation and cataracts in astronauts

For over 30 years, astronauts in Earth orbit or on missions to the moon have been exposed to space radiation comprised of high-energy protons and heavy ions and secondary particles produced in collisions with spacecraft and tissue. Large uncertainties exist in the projection of risks of late effects from space radiation such as cancer and cataracts due to the paucity [corrected] of epidemiological data. Here we present epidemiological [corrected] data linking an increased risk of cataracts for astronauts with higher lens doses (>8 mSv) of space radiation relative to other astronauts with lower lens doses (<8 mSv). Our study uses historical data for cataract incidence in the 295 astronauts participating in NASA's Longitudinal Study of Astronaut Health (LSAH) and individual occupational radiation exposure data. These results, while preliminary because of the use of subjective scoring methods, suggest that relatively low doses of space radiation may predispose crew to [corrected] an increased incidence and early appearance of cataracts.

LOCS III versus the Oxford Clinical Cataract Classification and Grading System for the assessment of nuclear, cortical and posterior subcapsular cataract

PURPOSE

To compare two methods of cataract grading for nuclear cataract, cortical cataract and posterior subcapsular cataract.

METHODS

The Melton Eye Study is an English community-based epidemiological study of the natural history of eye disease in people aged 55 to 74 years. The lenses of both eyes of 560 subjects were graded at the slit lamp using two cataract grading systems. The Oxford Clinical Cataract Classification and Grading System (OCCCGS) employs standard diagrams and Munsell colour samples for the grading of cortical, posterior subcapsular and nuclear cataract. The Lens Opacities Classification System III (LOCS III) uses photographic transparencies of the lens as standards. In both systems a decimalised score is assigned. We also graded the LOCS III standard images using the OCCCGS. Interobserver variation was calculated for both grading systems. Linear calibration lines are plotted for each type of lens opacity.

RESULTS

The relationship between LOCS III and OCCCGS for nuclear cataract and posterior subcapsular cataract is linear. The relationship for cortical cataract is linear once the LOCS III scores are squared. The intervals between the LOCS III images when ranked by the human eye using the OCCCGS are linear. Interobserver variation for both systems is good.

CONCLUSIONS

The linear calibration lines may be used to convert from one system to another and will be useful in comparing studies or performing meta-analysis. These results show that data from cataract studies using different clinical grading schemes can be compared.

New objective classification system for nuclear opacification

We have developed an autonomous objective classification scheme for degree of nuclear opacification. The algorithm was developed by using a series of color 35-mm slides acquired with a Topcon photo slit-lamp microscope and use of standard camera settings. The photographs were digitized, and first, and second-order gray-level statistics were extracted from within circular regions of the nucleus. Classifications of severity were performed by using these features as input to a neural network. Training versus classification performance was tested by using photographs of different eyes, and test/retest classification reproducibility was evaluated by using paired photographs of the same eyes. We demonstrate good performance of the classifier against subjective assessments rendered by the Wilmer grading system [Invest. Ophthalmol. Visual Sci. 29, 73 (1988)] and markedly better test/retest reproducibility.

Lens opacity increase in a longitudinal study: comparison of the lens opacities classification system II and lensmeter 701

We evaluated the ability of Lensmeter 701 (LOM) to detect changes in the transparency of the lens graded with the Lens Opacities Classification System II (LOCS II). In this prospective study 410 middle-aged Eastern Finnish men participating in the Kuopio Atherosclerosis Prevention Study were examined three times at eighteen month intervals, and lens opacities were graded with both LOM and LOCS II, the latter serving as the standard. Majority of the change in the LOM reading during the follow-up fell within the 95% tolerance interval of the apparatus (3.08 units). Only four eyes showing progression by LOCS II were detected by LOM. The association between LOM change and the change observed by LOCS II was not statistically significant, and the correspondence of the two methods was weak. It seems that the sensitivity of the LOM is not sufficient to detect small changes in the transparency of the lens over time.

Validation of methods for the assessment of cataract progression in the Roche European-American Anticataract Trial (REACT)

The Roche European-American Anticataract Trial (REACT) will assess the effect of antioxidants on progression of cataract in humans. This report evaluates the methods used in REACT. Seventy three subjects (139 eyes) with cortical (C), posterior subcapsular (P), nuclear (N) or mixed cataract were seen twice within two weeks for eye examinations, assessments of visual function, lens photographs and CCD images. The degree of cataract and nuclear color (NC) were assessed with subjective (LOCS III) and objective (computerized, CASE 2000 CCD) methods. Repeat visit values were used to calculate intraclass correlation coefficients (r1) and 95% tolerance limits (TL). A clinically significant change (CSC) was defined as one step in LOCS III. The relative power of each method to detect cataract change and sample sizes needed to achieve statistically significant results were calculated. The r1 values for visual function tests ranged from 0.76 to 0.88; if these tests of visual function were used to detect a clinically significant change in cataract severity, sample sizes of 840 to 2707 per group would be needed. The r1 values for LOCS III were 0.88 to 0.97, and sample sizes ranged from 50 to 135 per group. The r1 values for the CCD were 0.93 to 0.98, and sample sizes ranged from 1 to 42 with poorer values relating to measurement of P. We conclude that the methods used in REACT are reproducible. The analytical algorithms in the image analysis programs did not permit differentiation between C and P opacification; therefore, P cataract is best measured with LOCS III. REACT sample sizes are adequate to detect a difference of 0.2 LOCS III units/year between the mean rates of cataract progression in two groups.