Evaluating Cataract Development with the Scheimpflug Camera

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The physiological ageing changes of decreasing lens transparency were objectively evaluated in a total of 1,040 eyes selected from 1,685 individuals who were the subjects of population-based cataract epidemiological surveys performed in three climatically different survey fields in Japan. The lens transparency changes were evaluated from the light scattering intensity on thirteen different lens layers seen in slit images taken by the latest type of Scheimpflug camera. The mean percentage prevalence of cataracts in all the epidemiological survey subjects including grading from I to III, which was also judged objectively through documented images, was 64.6% in the Noto subjects, 46.6% in the Hokkaido subjects and 38.0% in the Okinawa subjects. The lens transparency at all of the measuring points decreased with ageing. The above changes, seen in the lenses of subjects in their 40s to 60s, were obviously more prominent compared with those seen in subjects in their 40s. Although there were some differences in transparency decrease with ageing among the subjects of the three areas, the authors tentatively propose to show the data obtained from the Noto subjects as representative of Japanese individuals. Lens transparency changes on each lens layer showed characteristic ageing changes and those of the representative four layers showed an exponential decrease in transparency. The decreasing ratio might accelerate from age as early as the mid-40s.

Section: Discussionmentioning

confidence: 99%

Changes in Light Scattering Intensity of the Transparent Lenses of Subjects Selected from Population-Based Surveys Depending on Age: Analysis through Scheimpflug Images

Fujisawa¹,

Sasaki²

1995

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“…These were Scheimpflug type cameras and retroillumination types. Although they have been applied not only to basic research, but also to clinical studies [8], the require ment of relatively sophisticated procedures including film development or densitometrical image analysis has produced results of variable quality [9][10][11]. The EAS-1000 exam ined in this study has the combined functions of Scheimpflug slit image and retroillumina tion image which were taken separately.…”

Section: Discussionmentioning

confidence: 99%

Reproducibility of Data Obtained by a Newly Developed Anterior Eye Segment Analysis System, EAS-1000

Sakamoto

Sasaki

Nakamura³

et al. 1992

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The reproducibility of data obtained from the recently developed anterior eye segment analysis system (EAS-1000) was evaluated. 40 normal eyes and 62 cataractous eyes were examined at Kanazawa Medical University Hospital or Yayoi Hospital. The radius of the corneal curvature, the corneal thickness, anterior chamber depth, whole lens thickness, anterior chamber angle and the scattering light intensity were all observed on a slit section of the lens, and the intrapupillary area of the cataractous shadow was measured from a retroillumination image. The measurements were made twice at an interval of 14.2 days. There were no significant differences between the data of the 1 st and 2nd examination in either place.

“…The combina tion of slit-lamp and retroillumination cameras has been chosen to give the maximum infor mation on lens opacities by photography. The technique of slit-image photography utilising Scheimpflug's principle has been well estab lished for studies of the lens [5], In the new system, a central 10-pixel strip from the digi tised image is analyzed in a manner equivalent to the earlier technique using manual densitom etry of film negatives |6, 7], Previous tech niques for the analysis of retroillumination photographs have usually depended upon the operator defining the clear lens areas. They have varied in complexity from manual grid counting methods, to interactive computer analysis techniques.…”

Section: Discussionmentioning

confidence: 99%

Application of Charged Couple Device Scheimpflug and Retroillumination Cameras to Lens Toxicity Monitoring in Man

Harris¹,

Brown²,

Bron³

1994

A newly developed charged couple device (CCD) camera and image analysis system (CASE 2000) has several theoretical advantages over film cameras for longitudinal study of cataract. We outline the use of this equipment in a year-long toxicity study of simvastatin. In this placebo-controlled trial, with two active treatment groups, 539 patients were recruited and 474 patients completed a second assessment at 1 year’s follow-up. No effect of the drug was found on the image analysis indices measured. The power of the study for the central nuclear dip and the retroillumination cataract index were 70 and > 99%, respectively, indicating the utility of the system even for relatively short studies of cataract.