Image analysis and glare sensitivity in human age-related cataracts.

BACKGROUND: A new glare disability test and a diagnostic instrument, the Halometer, were proposed for measuring intraocular light scattering in the presence of human cataracts. The objectives of this work were to introduce new methods of computer-generated analysis of lens images and a glare disability test to validate the use of two new tests to measure the severity of cataract and to document and quantify changes in lens clarity at diagnosis in a group of patients with age-related cataract with minimal to advanced opacities. METHODS: The authors followed 28 patients (46 eyes) with an average age of 66.9 +/- 6 years. Tests included ophthalmoscopy, visual acuity, the halometer glare disability test, stereocinematographic slit-image and retro-illumination photography with subsequent interactive digital image analysis and three-dimensional (3-D) computer graphics of the areas of lens light scattering/absorbing. RESULTS: The intra-reader reproducibility of measuring techniques for cataractous changes was good. The Halometer instrument measures the angular distance from the glare source from which a specific target can be recognised. The source and the target are in the same vertical and tangential planes and to measure the angular distribution of the glare light, it is necessary to measure the incident light angle between the source and the target, by measuring the distance between the source and the target. The clinical Halometry readings assessed the index of the forward scattered light that reaches the retina and produces a veiling luminance (glare). The glare sensitivity score was determined from the angle of the glare source using both red and green optotypes, so that the effects of light absorption were separated from those of light scatter. DISCUSSION: The interactive and automated computerised system discriminated the photographic image features of the back light-scattering/absorb centres within different grey thresholds and documented objective lens findings such as optical density, areas of equidensities, geometric surfaces, opacity grading. Digital image analysis gave a topographic and 3-D assembling and visualisation for nuclear, cortical and posterior subcapsular opacities in human lenses revealed from the optical scanning tomographic study of the anterior eye segment. The results indicate on agreement between clinical findings and applied quantitative techniques of analysis. This system has the potential to be a useful objective clinical assessment of cataract.

Efficacy of N-acetylcarnosine in the treatment of cataracts.

PURPOSE: To evaluate the effects of 1% N-acetylcarnosine (NAC) solution on lens clarity over 6 and 24 months in patients with cataracts. TRIAL DESIGN: Randomised, placebo-controlled study. PARTICIPANTS: 49 subjects (76 affected eyes) with an average age of 65.3 +/- 7.0 years with a diagnosis of senile cataract with minimum to advanced opacification in various lens layers. METHODS: 26 patients (41 eyes) were allocated to topical NAC 1% eyedrops twice daily. The control group consisted of 13 patients (21 eyes) who received placebo eyedrops and 10 patients (14 eyes) who did not receive eyedrops. MAIN OUTCOME MEASURES: All patients were evaluated at entry and followed up every 2 months for a 6-month period (trial 1), or at 6-month intervals for a 2-year period (trial 2), for best-corrected visual acuity and glare testing. In addition, cataract was measured using stereocinematographic slit-images and retro-illumination examination of the lens. Digital analysis of lens images displayed light scattering and absorbing centres in two- and three-dimensional scales. RESULTS: The overall intra-reader reproducibility of cataract measurements (image analysis) was 0.830, and glare testing 0.998. After 6 months, 90% of NAC-treated eyes showed improvement in best corrected visual acuity (7 to 100%) and 88.9% showed a 27 to 100% improvement in glare sensitivity. Topographic studies indicated fewer areas of posterior subcapsular lens opacity and 41.5% of treated eyes had improvement in image analysis characteristics. The overall ratios of image analysis characteristics at 6 months compared with baseline measures were 1.04 and 0.86 for the control and NAC-treated group, respectively (p < 0.001). The apparent benefits of treatment were sustained after 24 months' treatment. No treated eyes demonstrated worsening of vision. The overall visual outcome in the control group showed significant worsening after 24 months in comparison with both baseline and the 6-month follow-up examination. The overall clinical results observed in the NAC-treated group by the 24-month period of examination differed significantly (p < 0.001) from the control group in the eyes with cortical, posterior subcapsular, nuclear or combined lens opacities. Tolerability of NAC eyedrops was good in almost all patients, with no reports of ocular or systemic adverse effects. CONCLUSION: Topical NAC shows potential for the treatment and prevention of cataracts.