Incidence and management of posteriorly dislocated nuclear fragments following phacoemulsification

PURPOSE

To report the incidence, management and complications of nucleus dislocation into the vitreous during phacoemulsification.

METHODS

Retrospective review of 1250 consecutive phacoemulsification performed by consultants and residents in a teaching hospital.

RESULTS

The incidence of nucleus drops was 0.8% (10 out of 1250). Loss of nuclear fragments occurred during phacoemulsification in 9 patients. In one, the dislocation was caused by hydro-dissection. All except one patient (who refused further intervention) underwent pars plana vitrectomy with removal of nuclear fragments. Eight of them had intraocular lens (IOL) inserted at the time of cataract surgery or at vitrectomy; one patient was scheduled for a secondary IOL. Postoperative best corrected visual acuity ranged from 6/24-6/6; 8 patients achieved a vision of 6/12 or better. Complications included cystoid macular oedema (5 patients), retinal break (1 patient) and retinal detachment (1 patient).

CONCLUSION

Appropriate management of posteriorly dislocated nucleus can restore good visual acuity. The use of phacoemulsification mandates availability of referral facilities for management of complications.

Changes in refractive error over a 5-year interval in the Beaver Dam Eye Study

PURPOSE

To examine changes in spherical equivalent over a 5-year period in persons 43 to 84 years of age.

METHODS

All people 43 to 84 years of age and living in Beaver Dam, Wisconsin, in 1988 were invited for a baseline examination (1988-1990) and a 5-year follow-up examination (1993-1995). Refractions were determined according to the same protocol at both examinations. Aphakic and pseudophakic eyes were excluded as well as eyes with best corrected Snellen visual acuity of 20/40 and worse. After exclusions, refraction was obtained on 3007 right eyes and 3012 left eyes of the 3684 people participating in both examinations.

RESULTS

Right and left eyes behaved similarly. Spherical equivalent became more positive in the youngest subjects and more negative in older subjects. After adjusting for other factors, the 5-year change in spherical equivalent of those 45, 55, 65, and 75 years of age was +0.15, +0.18, +0.10, and -0.07D, respectively. Severity of nuclear sclerosis was related to the amount of change. Those with mild nuclear sclerosis at baseline had a change of +0.2 D, whereas those with severe nuclear sclerosis had a change of -0.5 D. The amount of change was also related to gender, diabetes, and age at onset of myopia. It was unrelated to education and baseline spherical equivalent.

CONCLUSIONS

Changes in spherical equivalent over a 5-year period were small. Before the age of 70, people became more hyperopic. After the age of 70, people became more myopic. Much of the myopic change may be related to increasing nuclear sclerosis.

Managing a dropped nucleus during the phacoemulsification learning curve

Three patients had a pars plana vitrectomy to remove retained nuclei within 72 hours after phacoemulsification performed by a surgeon making the transition from extra-capsular cataract extraction to phacoemulsification. After vitrectomy, the nuclei were brought to the midvitreous cavity from the retinal surface with a posterior segment phacofragmenter, emulsified, and completely removed. Then, a posterior chamber intraocular lens was implanted in the sulcus through the previous cataract surgery incision and remained well centered postoperatively. Postoperative complications included cystoid macular edema in 1 patient and choroidal detachment in another. No other complications were detected. Final visual acuity ranged from 20/60 to 20/30.

Different faces of the white cataract: a phaco surgeon's perspective

PURPOSE

To develop a system of categorizing white cataracts so that the salient features, as would be pertinent to phaco-emulsification surgery, could be recognized pre-operatively.

METHODS

Patients with total cataracts were carefully evaluated using slit-lamp biomicroscopy and slit-lamp photography. An attempt was made to determine whether pre-operative evaluation could ascertain the presence or absence of features of these cataracts that often cause surgical difficulties, namely, increased intralenticular pressure (ILP), milky cortex and brown nuclear colour.

RESULTS

Using a standardized method of biomicroscopic evaluation, it was found that the status of the ILP, cortex and nuclear colour could be determined consistently. Surgical strategies based on such a system of categorization has permitted white cataracts to be consistently managed using phacoemulsification.

CONCLUSIONS

Systematic pre-operative evaluation and categorization of white cataracts based on the ILP, status of the cortex and nuclear colour can permit proper surgical planning and successful management of such cases with phacoemulsification.

A mutation in the connexin 50 (Cx50) gene is a candidate for the No2 mouse cataract

PURPOSE

The No2 cataractous mouse mutant displays a bilateral, congenital, hereditary nuclear opacity of the ocular lens. The aim of this work was to identify and subsequently screen an optimal candidate gene for a mutation correlated and consistent with the observed phenotype.

METHODS

The No2 cataract was mapped in relation to genes and microsatellite markers by crossing to the wild mouse strain Mus spretus and then backcrossing to the inbred strain C3H/ HeH. The Cx50 (MP70) protein coding region and flanking sequences were amplified from normal parental as well as heterozygous and homozygous mutant genomic DNAs. These PCR products were then sequenced directly. Sequence data was corroborated by restriction analysis of PCR products.

RESULTS

Mapping of the No2 cataract placed it in the vicinity of Gja8, the gene encoding connexin 50 (MP70), a major component of lens fiber gap junctions. Amplification and subsequent sequencing of the Cx50 protein coding regions revealed a single A-->C transversion within codon 47. This sequence change resulted in the creation of an HhaI restriction endonuclease restriction site, allowing for corroboration of the sequence data via restriction analysis using this enzyme. The sequence alteration is also predicted to result in the nonconservative substitution of alanine (Ala) for the normally encoded aspartic acid (Asp) at this position within the polypeptide.

CONCLUSIONS

The identified mutation in Gja8 is both correlated and consistent with the cataract observed in the No2 mouse mutant, making it an ideal candidate for the cataract. This study provides the first evidence that a mutation in a lens connexin can result in congenital hereditary cataract, highlighting the importance of lens connexins in maintaining lens transparency.

Age-related nuclear lens opacities are associated with reduced growth before 1 year of age

PURPOSE

The aim of this study was to assess the relationship between fetal and infant growth, as measured by birthweight and weight at 1 year and the development of age-related lens opacities.

METHODS

A total of 1428 men and women who were born in Hertfordshire, United Kingdom, between 1920 and 1930, and for whom records of birthweight and weight at 1 year were available, were traced and invited for examination. Of these, 717 (50%) attended for ophthalmic examination. After dilation with tropicamide 1%, lens opacities were graded using the Lens Opacities Classification System (LOCS) III.

RESULTS

In this population of English men and women aged 64 to 74 years, most opacities were of the nuclear type. There was no association between birthweight and nuclear lens opacities. Weight at 1 year was negatively correlated with nuclear opacity score in adult life (P=0.001). Subjects in the highest tertile for weight at 1 year (>23 pounds) had an odds ratio of 0.35 (95% confidence interval, 0.17 to 0.74) for having a significant nuclear lens opacity (LOCS score of > or = 3) compared with people in the lowest tertile for weight at 1 year (<21 pounds). This association remained after controlling for age, sex, smoking, social class, adult height, and diabetes.

CONCLUSIONS

To our knowledge, this is the first time that such an association has been reported; it needs to be replicated in other populations. It could provide part of the explanation for the observed excess risk of cataract in developing countries.

A longitudinal study of body mass index and lens opacities. The Framingham Studies

OBJECTIVE

The purpose of the study was to determine whether body mass index (BMI) is an independent risk factor for the development of nuclear, cortical, or posterior subcapsular lens opacities.

DESIGN

A cohort study.

PARTICIPANTS AND METHODS

Eye examinations were conducted on surviving members of the Framingham Heart Study Cohort from 1973 to 1975 (Framingham Eye Study I) and again from 1986 to 1989 (Framingham Eye Study II). Data from the Framingham Heart Study, including weight measurements collected biennially from 1948, were used to examine associations between BMI (mean BMI across examinations, slope of BMI over time, and fluctuations in BMI) and the development of lens opacities. This analysis included 714 individuals, aged 52-80 years, who were free of lens opacities at the first eye examination.

MAIN OUTCOME MEASURES

Development of nuclear, cortical, and posterior subcapsular lens opacities.

RESULTS

A total of 444 persons developed lens opacities during the approximately 13 years between eye examinations. In logistic regression analyses that controlled for age, sex, education, diabetes, and smoking, the risk of developing cortical opacity increased with higher BMI at the time of the first eye examination (P = 0.002). Risk of cortical opacities also increased, at a borderline level of significance, with higher average BMI (P = 0.09) across examinations and increasing BMI levels over time (P = 0.10). There was a strong association between increasing BMI over time and the development of posterior subcapsular lens opacities (P = 0.002). No associations were found for nuclear lens opacities.

CONCLUSIONS

Although the mechanism explaining the association is unclear, these findings suggest that BMI, a potentially modifiable characteristic, is associated with the development of cortical and posterior subcapsular lens opacities.

Nuclear cataract and light scattering in cultured lenses from guinea pig and rabbit

PURPOSE

To compare calcium ionophore-induced cataract formation and in vitro light scattering in cultured lenses from guinea pig and rabbit.

METHODS

Lenses from guinea pig and rabbit were cultured for 5 or 6 days with calcium ionophore A23187. To assess the involvement of calpain in cataract formation; SDS-PAGE, immunoblotting and calcium determinations were performed. For in vitro light scattering, lens soluble proteins from rabbit were hydrolyzed for 24 h by either endogenous lens calpain, or by addition of purified m-calpain and then further incubated for up to 10 days. Light scattering was measured daily at 405 nm.

RESULTS

Lenses from younger guinea pigs cultured in A23187 first developed outer cortical opacities followed by nuclear cataract. Total calcium was markedly increased by A23187 in lenses of all ages. Proteolysis of crystallins and alpha-spectrin were observed in nuclear cataract in younger guinea pigs. This was attenuated with age, in association with the attenuation of cataract formation with age. Calpain 80 kDa subunit in the lenses cultured with A23187 was also decreased. Co-culture with SJA6017 or E64d (reversible and irreversible inhibitors of calpain, respectively) reduced A23187-induced nuclear opacities, proteolysis of crystallins and alpha-spectrin, and loss of calpain without affecting increased total calcium. In contrast, rabbit lenses cultured in A23187 did not develop nuclear cataract, although biochemical changes in cultured rabbit lenses were similar to those in cultured guinea pig lenses. Furthermore, no appreciable in vitro light scattering occurred in soluble proteins from rabbit lenses after activation of endogenous m-calpain, or after addition of exogenous purified m-calpain, although crystallins were partially hydrolyzed by calpain.

CONCLUSIONS

Both rabbit and guinea pig lenses undergo calpain-induced proteolysis upon elevation of lenticular calcium. However, factors in intact guinea pig lenses may promote light scattering and insolubilization after proteolysis by calpain, but these factors were not functional in rabbit lenses. Discovery of the factors promoting light scatter and insolubilization after proteolysis will help to explain the role of certain crystallin polypeptides in cataract formation.

Associations between lens features assessed in the Oxford Clinical Cataract Classification and Grading System

PURPOSE

To study the associations between eleven lens features graded according to the Oxford Clinical Cataract Classification and Grading System (OCCCGS).

METHOD

560 subjects taking part in the Melton Eye Study had their lenses graded according to the OCCCGS by one of two examiners. Associations between features were examined using log-linear models for categorised grades. Adjustment was made for age, sex and grader.

RESULTS

Within subjects, the two nuclear features, white nuclear scatter and brunescence, are closely related with one another, as are coronary flakes and focal-dots, but these two groupings are negatively associated. Cortical spoke, fibrefolds and waterclefts are all associated with one another and this group is positively associated with coronary flakes and focal-dots. Posterior subcapsular and anterior subcapsular opacity are associated with one another and with cortical spokes. A within-eye analysis gives similar results.

CONCLUSION

These associations may be important in defining cataract subtypes and in identifying minor features that indicate early cataract development.

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.

Prevalence of lenticular abnormalities in a population-based study: Oxford Clinical Cataract Grading in the Melton Eye Study

PURPOSE

To describe the distribution of the 11 features assessed by the Oxford Clinical Cataract Classification and Grading System (OCCCGS) in a population-based study.

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. Both lenses of 560 subjects were graded at the slit lamp using a decimalised version of the OCCCGS. Subject prevalences were estimated by logistic regression and the extent, when present, against normal errors regression.

RESULTS

White nuclear scatter (WNS), brunescence, cortical spoke (CS), anterior subcapsular opacity (ASC), fibre folds (FF), waterclefts (WC) and perinuclear retro-dots all increased with age (p < 0.05). Posterior subcapsular opacity (PSC), vacuoles, focal dots (FD) and coronary flakes (CF) did not significantly increase with age. Subject prevalences of the features and the mean Oxford scores when present were: WNS (1.33), brunescence (0.88), CS 36% (0.34), PSC 11% (0.52), ASC 2% (0.53), FF 18% (0.53), WC 17% (0.29), retro-dots 11% (1.15), vacuoles 59% (0.43), FD 98% (1.79) and CF 39% (1.24). Significantly more common in women were both coronary flakes (p < 0.001) and waterclefts (p < 0.05).

CONCLUSIONS

These are the first data on the distribution of these minor lesions in a population-based study. Coronary flakes and waterclefts are more common in women.

Confocal microscopy of human lens membranes in aged normal and nuclear cataracts

PURPOSE

To visualize the structure and determine the continuity of lipid membranes in lens fiber cells (LFCs) from human aged normal and cataractous lenses.

METHODS

Thick sections from human nuclear cataracts and aged normal lenses were stained with the lipophilic probe DiI, and then analyzed by confocal microscopy. Staining patterns of membranes were observed in individual optical sections or three-dimensional projections of z-series taken in longitudinal section and cross-section of LFCs from different regions within the lens nucleus.

RESULTS

DiI bound to and delineated the plasma membrane of LFCs from all regions of the lens nucleus. Three-dimensional projections of z-series from aged normal and cataractous lenses suggested that some of the stained lipid membranes were not continuous with LFC plasma membrane of cataractous lenses.

CONCLUSIONS

The results obtained using these methods demonstrated that lipid membranes, discontinuous with the plasma membrane of LFCs, were indicative of a novel process occurring predominately in cataractous human lenses.

Cigarette smoking and the risk of development of lens opacities. The Framingham studies

OBJECTIVE

To examine the association between cigarette smoking and the incidence of nuclear and non-nuclear lens opacities in members of the Framingham Eye Study Cohort.

PARTICIPANTS AND METHODS

Eye examinations were conducted on surviving members of the Framingham Heart Study Cohort from 1973 to 1975 (Framingham Eye Study I) and again from 1986 to 1989 (Framingham Eye Study II). Smoking data, collected biennially since 1948 in the Heart Study, were used to examine the relationship between cigarette smoking and the incidence of lens opacities. Two thousand six hundred seventy-five persons were examined in the Framingham Eye Study I. Our analysis included 660 persons, aged 52 to 80 years, who were free of lens opacities at the first eye examination.

RESULTS

During the approximately 12.5 years between eye examinations, lens opacities developed in a total of 381 persons, with nuclear opacities constituting the most frequent type. In logistic regression analyses that controlled for age, sex, education, and diabetes, a significant positive association with increasing duration of smoking and number of cigarettes smoked daily was found for nuclear lens opacities, alone or in combination (test for trend, P < or = .002), but not for nonnuclear opacities (test for trend, P = .62). Among the heavier smokers (persons who smoked > or = 20 cigarettes per day according to 6 or more biennial Framingham Heart Study examinations), 77% were still smoking at the time of the first eye examination. Persons who smoked 20 or more cigarettes per day at the time of the first eye examination were at substantially increased risk for the development of nuclear opacities than nonsmokers (odds ratio, 2.84; 95% confidence interval, 1.46-5.51). There was no apparent excess risk for persons with nonnuclear lens opacities (odds ratio, 1.42; 95% confidence interval, 0.65-3.07).

CONCLUSION

This study provides further evidence that cigarette smokers have an increased risk of developing nuclear lens opacities. The risk was greatest for heavier smokers, who tended to be current smokers and who smoked more cigarettes and for a longer duration.

Effect of cataract and pupil size on image quality with confocal scanning laser ophthalmoscopy

OBJECTIVE

To determine the effect of pupil size and cataract on the reproducibility and image quality obtained with confocal scanning laser ophthalmoscopy.

METHODS

Three image series were obtained with a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph, Heidelberg, Germany) before and after pupillary dilation in each of 39 subjects (8 normal subjects, 5 glaucoma suspects, and 26 patients with glaucoma). The cataract density was measured with both a lens opacity meter and the Lens Opacities Classification System III system. The image quality of each image series was subjectively scored on a scale of 0 (poor) to 9 (high) by 2 independent observers who were unaware of the cataract density and pupil size during image acquisition. The image quality and reproducibility were objectively evaluated using the SD of the mean topography image of each subject.

RESULTS

The mean pupil diameter in all subjects before and after dilation was 2.5 +/- 0.8 mm and 5.8 +/- 1.4 mm, respectively. After pupillary dilation, both the mean image quality score and mean SD of the mean topography image improved (from 4.5 +/- 3.5 to 7.4 +/- 2.3 and from 48.6 +/- 18.8 microns to 35.6 +/- 15.5 microns, respectively). The quality score of the images that were obtained before pupillary dilation was associated with the pupil size and density of nuclear and posterior subcapsular cataracts. The SD of the mean topography images that were obtained before pupillary dilation increased with a decreasing pupil size (P = .003) and an increasing density of the nuclear (P < .03), cortical (P = .02), and posterior subcapsular (P = .002) opacity.

CONCLUSIONS

Although pupillary dilation improved the image quality in most subjects, the improvement was sometimes small. Those subjects with small undilated pupils and/or cataracts may benefit most from pupillary dilation.

Light scattering and morphology of cataract formation in transgenic mice containing the HIV-1 protease linked to the lens alpha A-crystallin promoter

Two constructs of transgenic mice, TG61 and TG72, containing the HIV-1 protease linked to the lens alpha A-crystallin promoter develop cataract. The TG61 construct develop cataract in utero, while the TG72 construct exhibit frank opacities on the 24th day (homozygotes) and 26th day (hemizygotes) post natum. Polarized light scattering measurements were performed on cortical and nuclear sections of TG72 lenses from day 19 to day 26 as a function of scattering angle. The parallel components of the scattered light intensity increase gradually during opacification, the perpendicular components show very low values from day 19 to day 22 after which they increase exponentially. Analysis of the scattered light intensities yielded parameters describing the size of the protein aggregates, the size of the domains exhibiting optical anisotropy/birefringence, the difference in refractive index between (a) the protein aggregates and their surroundings and (b) the birefringent units and their surroundings. The last parameter accounts for the major portion of the increase in lens turbidity. The TG72 construct shows normal lens development on day 16. By day 21 the posterior cortex shows some disintegration, while the lens is still clear. By day 26 the lens nucleus migrates toward the posterior pole and there is a major alteration in the cortical fibers. Scanning electron microscopic studies reveal normal fiber cell organizations in control animals. In the TG72 construct the fiber cells are well organized at 16 days after birth but already develop some slight separation in the posterior cortical part of the lens. By post-natal day 21, the nucleus and the anterior cortex still exhibit well aligned fiber cell organization, but the posterior cortex shows disalignment. By day 26 in the TG72 construct, all areas of the lens show complete disintegration of the fiber cells and amorphous masses are present throughout. The light scattering parameters describing changes on the nanometer scale can be correlated with the changes in lens morphology during cataractogenesis that occur on the micrometer scale. In comparison, the light and scanning electron microscopic examinations of the postnatal TG61 construct show that the lens is severely disrupted and contains completely disintegrated fiber cell remnants at an early age.

Complications of retained nuclear fragments in the anterior chamber after phacoemulsification with posterior chamber lens implant

PURPOSE

We report two cases in which retained nuclear fragments in the anterior chamber after phacoemulsification and posterior chamber lens implant resulted in intraocular complications.

METHODS

Case reports.

RESULTS

In two eyes of two patients, retained nuclear fragments resulted in minimal anterior chamber reaction but substantial corneal edema and reduced visual acuity. Topical anti-inflammatory medications did not alter the postoperative course. Improvement occurred only when the nuclear fragments were surgically removed.

CONCLUSIONS

Retained nuclear fragments in the anterior chamber can cause corneal edema and reduced vision that may be reversed by removing the fragments.

Some plasma constituents correlate with human cataract location and nuclear colour

AIMS

To look for differences in levels of various plasma constituents between pair-matched controls and patients who had cataracts classified by location and appearance of lens opacity and nuclear colour in order to identify systemic risk factors.

METHODS

One thousand patients were taken from the cataract waiting list of a specialist eye hospital. For each patient, a matched control of the same sex and half-decade of age but without cataract was taken from the patient-list of the family doctor of the patient; the control was the next alphabetically after the patient on the doctor's list. At an early morning visit to the homes of both patients and controls, fasting, a team of nurses performed venepunctures and collected information for a questionnaire. Eye examinations were performed by a team of ophthalmologists.

RESULTS

Predominantly nuclear cataract was significantly associated with raised plasma alanine aminotransferase and bilirubin, posterior subcapsular cataract with increased calcium and urea, cuneiform with reduced potassium, mature/hypermature with raised potassium and reduced total carbon dioxide. The following were consistently significantly associated with all forms of cataract; diabetes and raised plasma glucose (not in non-diabetics), use of steroid medication, raised levels of cortisol (steroid users excluded), albumin, alkaline phosphatase, gamma-glutamyl transpeptidase, sodium and total protein and reduced levels of cholesterol and albumin/(total protein-albumin) ratio (an approximation for the albumin/globulin ratio). The multivariate analysis indicated that the most important non-specific cataractogenic effects were those of increased total protein, diabetes and use of steroid medication.

CONCLUSION

This and other studies support, broadly, the conclusions that senile or age-related cataract is not merely caused by increasing age and also that various morphological types have different risk factors. The mechanisms underlying the biochemical associations with different patterns of lens opacification and the identification of the ultimate risk factors remain to be elucidated.

Discrete nuclear sclerosis in young patients with myopia

OBJECTIVE

To review a series of young patients with myopia who had a visually disabling cataract.

DESIGN

A retrospective review of 12 consecutive patients who had a visually disabling cataract and who were examined at the Cornea Service of the University of Illinois at Chicago.

RESULTS

The mean age of the patients was 44 years (range, 34-54 years). The mean best-corrected visual acuity of the patients was 20/50, and the ocular history of the patients included a progressive decrease in vision. Six patients experienced disabling monocular polyopia. Their presumed diagnoses ranged from keratoconus to myopic degeneration. All of the patients noted resolution of their symptoms after cataract extraction.

CONCLUSIONS

These patients are a select group that tends not to follow the established associations between visually significant lens opacities, age, and myopia. Cataract extraction is therapeutic, and prompt diagnosis can obviate unnecessary testing and repeated office visits.

Outcomes of dropped nucleus during phacoemulsification

PURPOSE

To evaluate the clinical outcome of vitrectomy in the management of dropped nucleus during phacoemulsification.

METHOD

Twenty-five consecutive patients who underwent pars plana vitrectomy for the management of dropped nucleus from phacoemulsification, over a 36-month period, were studied. Twenty-two patients underwent vitrectomy within 15 days of cataract surgery. Most of the patients were followed for more than 6 months.

RESULTS

Final visual acuity was 20/40 or better in 71% (17/24) of eyes and 20/50 in 8% (2/24). Visual acuity was 20/70 or worse in 21% (5/24) of patients. Complications included persistent cystoid macular edema in three eyes, epimacular proliferation in two eyes, and a choroidal detachment in one eye.

CONCLUSION

Poor visual outcome after dropped nucleus at phacoemulsification cataract extraction can be avoided if managed by prompt pars plana vitrectomy.

Dislocation of the lens nucleus into the vitreous cavity after standard hydrodissection

PURPOSE

Having encountered dislocation of the lens nucleus into the vitreous cavity immediately after continuous tear capsulorhexis and hydrodissection of the nucleus, we examined common features of eyes with this complication.

METHODS

We reviewed consecutive cases of cataract extraction.

RESULTS

The complication occurred in four of 10,126 eyes. All four eyes were in elderly patients and except for the patient whose contralateral eye had pseudoexfoliation syndrome, all eyes had an increased axial length.

CONCLUSION

In elderly patients with eyes that have a long axial length or pseudoexfoliation, we recommend performing hydrodissection with extreme care and only when necessary.

Fiber cell morphology and cytoplasmic texture in cataractous and normal human lens nuclei

PURPOSE

The goal of this study was to compare the ultrastructure of the oldest cells in opaque and transparent human lenses.

METHODS

Age-related nuclear cataracts, late-onset diabetic nuclear cataracts and normal aged lenses were examined by transmission electron microscopy. Cross-sectional profiles of fiber cells in the embryonic, fetal and juvenile nuclear regions were obtained to facilitate direct comparisons between lens regions and between sample groups. Image analysis was performed to determine cross-sectional areas of fiber cells in each region.

RESULTS

The average cross-sectional area increased approximately sixfold from the outer to the inner nuclear regions in all lenses measured. In each nuclear region, fiber cells displayed a characteristic size, shape, arrangement and type of interdigitations which were consistently seen in all the lenses examined. Some lenses had more complex interdigitations than others. Gap junctions were identified as pentalamellar structures having 16 nm width and appeared identical throughout the nuclei of both normal and cataractous lenses. The cytoplasm of all lenses was smooth and free of large density variations. However, the cytoplasm of some cataractous lenses appeared more granular in texture than noncataractous lenses. Cellular degeneration, debris or large cellular defects were not seen in the cores of cataractous lens nuclei.

CONCLUSIONS

These results indicate that only minor ultrastructural differences exist between the oldest fiber cells in normal and cataractous lenses, and that the presence of extensive cellular damage and disruptions is not necessary for the generation of nuclear opacities in aged lenses. Our observations suggest that light scattering sufficient for vision impairment may involve structural alterations much smaller than previously proposed.

Phacoemulsification and posterior chamber intraocular lens implantation

OBJECTIVE

The study was designed to evaluate the therapeutic effects of phacoemulsification and PMMA posterior chamber intraocular lens implantation.

METHODS

The surgery was performed on 74 eyes of 67 patients with senile, complicated and congenital cataracts.

RESULTS

Post-operatively, the visual acuities with spherical correction or without correction were 0.5 or better in 80.5% at one week and with correction, in 97.6% at three months. The mean astigmatism was 1.90 +/- 1.15 D at one week and 0.93 +/- 0.55 D at three months which were respectively less than that in the control group with a 10-12 mm large incision (P < 0.001), but almost the same as that in the control group with a small incision and manual nucleus division technique (P > 0.05). The main complications were iris bite in 6 eyes, capsular rupture in 2 eyes and aseptic hypopyon in one eye. The selection of cases, surgical techniques and management of intraoperative complications were discussed.

CONCLUSION

These results suggest that phacoemulsification be applied extensively. However, that it has more complications and risk must be emphasized for a beginner.

Precataractous changes affect lens transparency in the selenite cataract

Selenite treatment of the preweanling rat stabilized the transparency of the lens nucleus to decreasing temperature. Hence, we compared properties of the cortex and nucleus from lenses of selenite-treated and age-matched control rats. A subcutaneous dose of 30 nmol Na2SeO3/g body weight was administered to 10- to 13-day-old Sprague-Dawley rats. Uninjected, age-matched littermates served as controls. As required, lenses were frozen in liquid N2 and separated into nuclear and cortical-epithelial fractions. Transparency of solutions of lens proteins (90-100 mg per ml) was monitored from 30 to 2 degrees C as percent transmittance (%T) at 490 nm. The critical phase separation temperature, Tc, was the temperature at 80%T. Protein associations were monitored with gel filtration chromatography. The nuclear 'cold cataract', in intact lenses, formed at similar temperatures at 14 and 15 days of age, but at a significantly lower temperature when the lenses were from a selenite-treated rat. The Tc, however, was greater by 1.5-2 degrees C for solutions of proteins isolated from whole lenses or lens nuclei from rats 24 and 48 h after treatment with selenite. Further, less gamma-crystallin was associated with the alpha-crystallin fraction in extracts from the nucleus of lenses from treated rats. Altered phase separation properties occurred as an early event in the etiology of selenite cataract. The different in vivo and in vitro responses to temperature indicated that properties of lens crystallins do not solely establish transparency in the intact lens.

Measured changes in cataract over six months: sensitivity of the Nidek EAS-1000

Lens opacities in 98 eyes from 63 consecutive outpatients with cataract were recorded by both retroillumination and Scheimpflug slit methods by one operator. This was repeated at 26 +/- 1 weeks. Image analysis used the EAS-1000 software. Cortical and posterior subcapsular (PSC) cataracts were measured in retroillumination images as density more than 14 cct units below background density. Linear densitometry of white scattered light along the optical axis was measured for slit images by both peak density and mean density ('area under the curve'). Retroillumination images showed no discernible change over 6 months (the regression coefficient being as for the intersession reliability). Half of the Scheimpflug slit images could not be analysed because overlying cortical changes masked the more posterior parts of the lens. The other 49 eyes showed a significant increase in nuclear white scatter after 6 months, with greater degrees of change occurring in those eyes with the greatest amount of nuclear cataract initially. This is reflected by the decreased intraclass correlation coefficient (R = 0.42). The area of lens showing greatest change was the anterior fetal nucleus. The Nidek EAS-1000 is able to detect changes over a 6-month period in nuclear density but not in cortical or PSC cataract. The rate of progression of nuclear white scatter increases as the lens opacity becomes more dense. The ability to detect change in cataract over 6 months has implications for epidemiological studies and for trials of anti-cataract drugs.

Reoperation after failed macular hole surgery

PURPOSE

The authors determined the anatomic and visual success rates of vitrectomy in patients who have failed previous macular hole surgery.

METHODS

Standardized Early Treatment Diabetic Retinopathy Study (ETDRS)-style best-corrected visual acuity was measured in each patient pre- and postoperatively. Surgery was performed at two centers using a standardized protocol, as previously reported, using 1330 ng bovine-derived transforming growth factor-beta 2 (TGF-beta 2) and 16% perfluoropropane internal gas tamponade. Endpoint analyses were conducted for anatomic closure of the hole, visual improvement of three or more ETDRS lines, and final visual acuity of > or = 20/63 and > or = 20/40.

RESULTS

Forty-eight failing macular hole surgery were reoperated. The anatomic results showed closure of the hole in 40 (83%) cases at the end of the mean follow-up interval of 7.4 months. The visual acuity improved in greater than or equal to three lines in 52%, was > or = 20/63 in 54%, and was > or = 20/40 in 25% of reoperated eyes. The only factor associated with a better final visual acuity was preoperative visual acuity better than 20/80. Nuclear sclerosis leading to cataract extraction was observed in 13 (30%) of 43 initially phakic eyes.

CONCLUSIONS

Macular hole closure was induced in this subset of reoperated patients. Visual improvement occurred often, although in a lower percentage than has been reported for primary surgical eyes. Repeat vitrectomy should be considered in patients with persistent macular hole after failure of primary surgery.

Colour of the nucleus as a marker of nuclear hardness, diameter and central thickness

Hundred and thirty patients, aged above 40 years, with senile cataract were examined. Age and colour were selected as the probable preoperative indicators of nuclear hardness. The lens material collected after manual extracapsular extraction was washed and the nucleus isolated. The diameter and central thickness of the nucleus were measured; the mean diameter and mean central thickness were 7.13 mm +/- 0.76 and 3.05 mm +/- 0.48, respectively. The hardness of the nucleus was measured with a lens guillotine designed by us. Regression analysis was applied to the parameters measured and these were compared with the colour and age. The parameters measured had the following relationship: Colour vs hardness (r value = 0.7569) (p < 0.001) Colour vs diameter (r value = 0.3962) (p < 0.001) Colour vs central thickness (r value = 0.4785) (p < 0.001) Age vs hardness (r value = -0.0499) (p > 0.05) Age vs diameter (r value = 0.0987) (p > 0.05) Age vs central thickness (r value = 0.1700) (p > 0.05) The values showed that colour had a statistically significant relationship with all the 3 parameters (p < 0.001), while age had no significant relationship with the same parameters. The results indicated that colour can be used more reliably to predict physical characteristics of the cataractous lens nucleus, the preoperative knowledge of which would help the surgeon in planning small-incision surgery including phacoemulsification.

Cigarette smoking and risk for progression of nuclear opacities

OBJECTIVE

To examine the relationships between smoking and the 5-year incidence of new nuclear opacities and between smoking and the progression of nuclear opacities in a prospective study of a cohort of Chesapeake Bay watermen.

METHODS

A total of 442 men (age, > or = 30 years in 1985) with paired, gradable lens photographs in at least one eye in both 1985 and 1990 were studied. Photographs were graded by two readers who used the grading scheme of the Wilmer Institute, Baltimore, Md, with severity ranging in decimal units between 0.0 and 4.0. Data on the smoking history of the subjects were collected by personal interviews that were conducted in 1985 and updated in 1990.

RESULTS

The incidence and progression of opacities increased with age. A nonsignificant association was observed between smoking (for both current and ex-smokers) and the incidence of a nuclear opacity. The risk of progression of nuclear opacities of less than grade 3 at baseline to grade 3 or worse was 2.4-fold higher among current smokers in 1985, compared with that among ex-smokers and nonsmokers (95% confidence limits: 1.0, 6.0) after adjustment for age, baseline opacity status, and alcohol use. An 18% increased risk of progression was significantly associated with each pack-year that a subject smoked between 1985 and 1990.

CONCLUSION

These data confirm previous findings that smoking is associated with a nuclear opacity, particularly with progression to severe opacities.

Pulverulent nuclear cataract in the Norwegian buhund

Pulverulent cataracts were diagnosed in 52 of 102 Norwegian buhunds, with both sexes being equally affected. All the dogs were otherwise considered clinically healthy. Initial lens changes were visible from six and a half weeks of age as small dots parallel to the suture lines behind the nucleus. Gradually, the opacities along the suture lines became more opaque until, by the age of four to five and a half years, they had progressed to involve the fetal nucleus which then resembled a ball of candy floss. The outer part, the adult nucleus, usually remained clear, and the cortex was not involved. The ages of the dogs in the present study ranged from three and a half weeks to 12 years at first examination. An outcross of an affected bitch to a mixed-breed dog resulted in three puppies, of which two were affected. The retinas could be evaluated in all the examined dogs, and revealed no abnormalities except for one case of focal retinopathy. In addition to the pulverulent cataracts, 10 cases of cortical cataracts were diagnosed, three of which also had pulverulent cataracts. Based on the pedigrees, an autosomal dominant mode of inheritance with a high degree of penetrance is suggested for pulverulent cataract.

Nuclear sclerotic cataract after vitrectomy in patients younger than 50 years of age

PURPOSE

To evaluate the occurrence of cataract formation after pars plana vitrectomy and gas-fluid exchange in patients younger than 50 years of age.

METHODS

Twenty-eight patients younger than 50 years of age with bilaterally symmetric crystalline lenses underwent pars plana vitrectomy and gas-fluid exchange in one eye. Postoperatively, lens photographs were used to assess any asymmetry between the surgical and nonsurgical eye. Lens photographs were graded by three independent masked observers using the Lens Opacities Classification System III (LOCS III). Significant cataract progression was defined as either cataract extraction in the surgical eye or a greater than a 0.9 LOCS III unit difference in lens opacity between the surgical and nonsurgical eye. Results were compared with 28 patients older than 50 years of age who had undergone identical surgery.

RESULTS

In only 7% of patients younger than 50 years of age (mean age, 36.5 years; range, 16-47 years) did significant lens opacity develop in the surgical eye compared with the nonsurgical eye during the follow-up period (mean follow-up, 25.4 months; range, 12-43 months). Of patients older than 50 years of age (mean age, 68.2 years; range, 51-85 years), 79% developed significant lens opacity in the surgical eye compared with the nonsurgical eye during the follow-up period (mean follow-up 27.3 months; range, 12-49 months). The difference in cataract progression between patients younger than 50 years of age and patients older than 50 years of age was statistically significant (P < 0.0000001).

CONCLUSION

Pars plana vitrectomy with gas-fluid exchange is minimally cataractogenic within the first few years in patients younger than 50 years of age.

UV-B and early cortical and nuclear changes in the human lens

Experimental studies in mice and rats have shown that UV (B) irradiation leads to specific lens changes, viz. yellowing of the nucleus and a multilayered epithelium in the anterior pole with disrupted cortical fibres underneath. Biomicroscopic and ultrastructural studies on ageing human lenses revealed yellowing of the lens nucleus and locally ruptured membranes and small opacities in the equatorial cortex. No changes in the anterior pole were ever observed. This discrepancy between the human and animal lens, contraindicating UV as an important risk factor for human cataract, is discussed and may be due to several factors: (1) a difference between the high level acute and low level chronic irradiation; (2) species differences: nocturnal animals may be unable to cope with bright light exposure; (3) differences in scavenger and other defense mechanisms between humans and animals.

Posterior lens dislocation during attempted phacoemulsification

Mechanisms of posterior lens dislocation during phacoemulsification have been suggested, but the actual mechanism involved has not been demonstrated. Chart reviews of cataract surgeries performed at Indiana University from 1991 until the present identified nine cases of posterior lens dislocation that occurred during phacoemulsification. In four, the procedure was converted early to a can-opener capsulotomy. Cadaver eye studies showed the role of an imperfect capsulorhexis in extending tears while a "trap door" was being formed for posterior nuclear dislocation during phacoemulsification.

Serum carotenoids and tocopherols and severity of nuclear and cortical opacities

PURPOSE

To determine whether higher levels of individual carotenoids and tocopherols in the serum are related to less severe nuclear and cortical opacities within the general population.

METHODS

Levels of individual carotenoids and tocopherols in the serum were determined in 400 randomly selected persons aged 50 to 84 years participating in the Nutritional Factors in Eye Disease Study of Beaver Dam, Wisconsin. Severity of nuclear and cortical opacities was assessed from lens slit lamp and retroillumination photographs taken at the same time. Relationships between serum levels of nutrients and prevalence of these opacities were evaluated using logistic regression analysis accounting for known possible confounders.

RESULTS

Higher levels of individual or total carotenoids or alpha-tocopherol in the serum were not associated with less severe nuclear or cortical opacities overall. However, associations differed between men and women and within specific population subgroups. A significant trend for lower odds for either type of opacity with increasing levels of beta-carotene in the serum was observed in men. For nuclear sclerosis, this protective association with beta-carotene was found in younger but not older men. Higher levels of three other carotenoids (alpha-carotene, beta-cryptoxanthin, and lutein) in serum were significantly related to lower odds for nuclear sclerosis only in men who smoked. In contrast to these inverse associations observed in some subgroups, higher levels of some carotenoids and alpha-tocopherol often were directly associated with nuclear sclerosis, particularly in women.

CONCLUSIONS

Higher levels of carotenoids and tocopherols are not consistently associated with less severe opacities in the general population.

Structure and regional water content of bovine, porcine, and human lenses examined with proton nuclear magnetic resonance imaging

A proton nuclear magnetic resonance instrument with a 7-tesla field was used for nuclear magnetic resonance imaging (NMRI) to study bovine, porcine, and human lenses. The NMRI images show detailed changes in the water for normal and diseased tissues. The alterations in the nucleus and the cortex in relation to the health of the tissue are clearly illustrated.

Progression of nuclear sclerosis and long-term visual results of vitrectomy with transforming growth factor beta-2 for macular holes

PURPOSE

We studied the progression of cataracts and visual acuity up to 36 months after vitrectomy and instillation of transforming growth factor beta-2 for treatment of full-thickness macular holes.

METHODS

Sixty-four eyes with idiopathic and two with traumatic macular holes in this prospective consecutive series were divided into the following two groups: 56 phakic eyes were treated with 70, 330, or 1,330 ng of transforming growth factor beta-2 to study the progression of cataracts, and 31 phakic or pseudophakic eyes were treated with 1,330 ng of transforming growth factor beta-2 to study the long-term visual acuity after macular hole surgery.

RESULTS

Eyes in the cataract progression study had a mean preoperative nuclear sclerosis grade of 0.4, which increased to 2.4 on final lens examination at a mean of 12.4 months postoperatively. The amount of nuclear sclerosis increased progressively with duration of follow-up, and 16 (76%) of 21 eyes followed up for 24 months or more required cataract extraction. The mean preoperative posterior subcapsular cataract grade was 0.0 and increased only slightly to 0.25 on final lens examination. All eyes had initial successful closure of the macular hole, but the macular hole reopened in two eyes (between six and 12 months and at 19 months) for an overall success rate of 29 (93.5%) of 31 eyes at a mean of 19.5 months. The visual acuity increased two or more Snellen lines in 29 (93.5%) of 31 eyes. The final visual acuity was 20/40 or better in 23 (74%) of 31 eyes and the visual improvement was stable in eyes followed up for three years.

CONCLUSIONS

Nuclear sclerotic cataracts progress substantially after macular hole surgery with a long-acting intraocular gas tamponade. The visual acuity often decreases 12 or more months after vitrectomy because of cataract progression, but the visual results of vitrectomy and transforming growth factor beta-2 for macular holes are excellent when the cataracts are removed.

Comparison of linear, multilinear and mask microdensitometric analyses of Scheimpflug images of the lens nucleus

We wanted to determine the agreement among three methods currently used to measure the average density of the nucleus from a Scheimpflug video image of the lens, namely, the multilinear, linear and mask techniques. Using the NEI Scheimpflug Cataract Imaging System, video images of the lens were obtained from 49 eyes of 31 consecutive patients with predominantly nuclear opacities of varying severities. For each image, 3 separate determinations of the average nuclear density [in optical density units (odu)] were obtained by one analyst sequentially applying each of the three methods. Repeat measurements were obtained by the same analyst one week apart to evaluate reproducibility (using 95% error range), of each of the methods. Pairwise comparisons of the 3 methods were also done. Only the error due to outlining of the nucleus was assessed. Reproducibility of each method was excellent. The 95% error ranges were +/- 0.015 odu for the linear, +/- 0.013 odu for the multilinear, and +/- 0.017 odu for the mask methods. Very strong linear relationships were observed between the linear and multilinear methods (R2 = 0.99), between the linear and mask methods (R2 = 0.97), and between the multilinear and mask methods (R2 = 0.98). Simple linear regressions calibrating these three methods against each other would facilitate comparison of density measurements using any of these methods for analysis of Scheimpflug images of the lens nucleus.

Lens hardness in mature cataracts

A cataract is said to be mature when all the cortical fibres become opaque. Depending on the pathophysiological processes that cause the cortical fibre opacification this phenomenon may be associated with a varying degree of nuclear sclerosis. A relationship between lens hardness and degree of nuclear sclerosis in non-mature cataracts has been demonstrated previously. This study aimed to investigate the relationship between the hardness of mature cataracts and the transmitted nuclear colour, age and rate of progression of the cataract. Thirty-eight patients with mature cataracts were assessed prior to extracapsular cataract surgery. The nuclear colour that was transmitted through the opaque cortex was graded using reference photographs. Age and duration of visual symptoms were recorded and lens hardness was measured by a specially designed lens guillotine. Multivariate analysis of data indicates a relationship between hardness of a mature cataract and the transmitted nuclear colour and age (adjusted R2 = 0.59). There is also a tendency for hardening of the lens as the duration of visual symptoms increases. By considering these clinical markers, the cataract surgeon can estimate the hardness of the lens and therefore its suitability for phacoemulsification.

Reproducibility of the NEI Scheimpflug Cataract Imaging System

PURPOSE

The NEI Scheimpflug Cataract Imaging System was developed to allow for easy, accurate and reproducible image analysis of nuclear cataracts. This study was undertaken to determine the reproducibility of densitometric measurements of the lens nucleus using this modified system.

METHODS

Replicate Zeiss Scheimpflug images of the lenses in 143 eyes were obtained by one photographer. Normal and cataractous lenses (without central cortical or anterior subcapsular opacities) were sampled. Images were stored after testing for adequacy using immediate exposure checking. Densitometry of the nuclear region was then performed for each image. The interval within which 99% of the differences between repeat measurements may be expected to lie was used as a measure of reproducibility (99% range).

RESULTS

A 99% range of +/- 0.023 optical density units (odu) was obtained for nuclear densities < 0.30 odu (125 eyes). For lenses with nuclear densities > or = 0.30 odu (18 eyes), the 99% range was +/- 0.14 times the first measurement.

CONCLUSION

This study shows the excellent reproducibility of this Scheimpflug imaging system in the nuclear region and demonstrates its usefulness in studies on nuclear cataracts, particularly for natural history studies and clinical trials of anti-cataract drugs.

Risk factors for cortical, nuclear, posterior subcapsular and mixed cataract: a case-control study

A case-control study was conducted to evaluate risk factors for cortical, nuclear, posterior subcapsular and mixed cataract. The 385 cases and 215 controls (age range 40-75 yrs) included in the study underwent a complete ophthalmological examination and laboratory blood tests, and were interviewed about behavioral variables, environmental exposure and their medical history. Lens opacity was classified using the 'Lens Opacity Classification System II' (LOCS II). On multivariate analysis, the risk factors for cortical cataract were the presence of diabetes for more than five years (OR = 3.7) and increased serum K+ and Na+ levels. A history of surgery under general anesthesia and the use of sedative drugs were associated with reduced risk (OR = 0.4). Posterior subcapsular cataract was associated with the use of steroids (OR = 18.2) and diabetes (OR = 8.1), and nuclear cataract with calcitonin (OR = 5.7) and milk intake (OR = 0.25). Mixed cataract was associated with a history of surgery under general anesthesia (OR = 0.5). Some of these results are consistent with the findings of similar studies performed in different geographical areas, others are not. The results suggest a possible role of electrolyte imbalance in the development of senile cataract.

Is age-related maculopathy associated with cataracts?

OBJECTIVE

To evaluate the relationship between three types of cataract or cataract surgery and age-related maculopathy.

DESIGN

Population-based prevalence study.

PARTICIPANTS

A total of 4926 people participating in The Beaver Dam Eye Study from 1988 through 1990.

MAIN OUTCOME MEASURES

Grading of photographs for nuclear sclerosis, cortical cataract, and posterior subcapsular cataract and signs of age-related maculopathy was performed using standardized protocols.

RESULTS

After adjusting for other risk factors, nuclear sclerosis was associated with increased odds of early age-related maculopathy (odds ratio [OR], 1.96; 95% confidence interval [CI], 1.28 to 3.01) but not of late age-related maculopathy (OR, 1.38; 95% CI, 0.52 to 3.63). Neither cortical nor posterior subcapsular cataracts were related to age-related maculopathy. There were increased odds of early age-related maculopathy in eyes that had undergone cataract surgery.

CONCLUSION

These data suggest a possible commonly shared pathogenesis between nuclear sclerotic cataract and age-related maculopathy.

Water content, lens hardness and cataract appearance

Hardening of a cataractous lens is associated with the clinical appearance of brunescence and advancing age. Alterations in the nature and concentration of proteins, lens fibre compaction and other biochemical changes may all be contributing factors towards increased hardness. As the nucleus confers most of the rigidity to the lens and water content decreases towards the centre of the nucleus, the hardness might be thought to be related to total water content. To study the relationship between water content, hardness and the clinical appearance of cataract, 135 lenses were obtained from eyes undergoing extracapsular cataract surgery. The cataracts were assessed and classified pre-operatively. Lens hardness was determined by a specially designed guillotine and water content was measured by weighing the lens before and after desiccation. A regression analysis was carried out to look at the variation of lens water content with hardness, degree of nuclear sclerosis, extent of cortical and posterior subcapsular cataract, vacuolation and age. Multivariate analysis of data demonstrated a relationship between lens hardness and lens water content, degree of nuclear sclerosis and age (R2 = 0.59). An association could not be detected between lens water content and age, degree of nuclear sclerosis, extent of cortical and posterior subcapsular cataract and vacuoles. This study suggests that hardening of the lens is reflected by a respective decrease in water content. Increased hardness is associated with coloration and advancing age.

Response of mouse lens to central needle injury

We examined the difference in response to different degrees of injury in the mouse lens. The anterior side of the lens was pricked through the cornea by a microsyringe with a 31-gauge needle or an ordinary needle. The location of the needle tip was mostly marked with Evans' blue (EB) stain. At least three types of responses were recognizable. The first was a recovery type in which the wound was healed by an epithelial reaction. EB was localized at the superficial zone of the anterior cortex. The second was a type in which the change within the lens was stationary after forming a spherical body with a slightly smaller diameter than that of the entire lens. EB was observed in the intermediate zone of the anterior cortex. The third was a rapid progressive type of cataract which caused lens opacity within 3 days. The trace of the needle tip was observed around the perinuclear zone. These results suggest that the cortex of the mouse lens consists of three zones which may be functionally different around the lens nucleus: superficial, intermediate and perinuclear zones.

Comparison of the lens opacities classification system II and Lensmeter 701

We examined 447 hypercholesterolemic and 108 normocholesterolemic Eastern Finnish men, aged 42, 48, 54, or 60 years, who were participating in the Kuopio Atherosclerosis Prevention Study. Two newly developed lenticular opacity grading methods, the Lens Opacities Classification System II and Lensmeter 701, were compared. There was fair agreement between the two grading methods for nuclear color and opalescence, but the agreement was weaker for cortical and posterior subcapsular opacities. The Lens Opacities Classification System II grading of nuclear opacities explained 48% (for the right eye) and 32% (for the left eye) of the variation of Lensmeter readings. Attributable fractions were lower for the other types of lens opacities.