A New Method for Retroillumination Photography of Cataractous Lens Opacities

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.

Section: Discussionmentioning

confidence: 95%

Measured Changes in Cataract over Six Months: Sensitivity of the NidekEAS-1000

Foo

MacLean²

1996

“…Retroillumination photography of cataractous lenses developed by Kawara and Obazawa [8] has been widely applied in both basic and clinical cataract reaserch. The advantage of this methodology is that the whole figures of cataractous opacification can be caught on one plane, but it contains opacifications that existed in all of the lens layers.…”

Section: Discussionmentioning

confidence: 99%

Computed Tomographic Images and Three-Dimensional Expression of Crystalline Lens Findings from Multiple Slices of Scheimpflug Slit Images

Sakamoto

Sasaki²

1995

Although the observation of lens changes in clinical examination has been made through a slit lamp microscope under dilated pupil, precise documentation and analysis of lens changes are presently possible through Scheimpflug photographic images. However, the methodology is still unsatisfactory because the image analysis is two dimensional. In order to overcome this disadvantage, the authors aimed at developing a new methodology for obtaining computed tomographic images of the lens. 60 Scheimpflug slit images of a cataractous human lens were taken by an anterior eye segment analysis system as digital data. After the locations of the whole slit images had been matched, reconstruction of the coronal section line images was performed utilizing extracted image information. The total number of reconstructed coronal section images in additional procedures of the image interpolation was 150. Computed tomography of the lens image was made from those 150 images. A whole lens figure was also demonstrated as a moving three dimensional image.

“…Among several new diagnostic methods for cataracts, the method of image analysis has been introduced in the cataract research field since the late 1980s [5], They include Scheimpflug slit image and retroillumination documentation of lens opacification [6,7], Of those two, Scheimpflug slit-imaging is espe cially suitable for the quantitative evaluation of nuclear opacification, in spite of the in volvement of several complicated procedures, including film development, standardization of the film density and densitometry of the final images. An anterior eye segment analysis system developed by the authors and utilized in this investigation has overcome such com plications.…”

Section: Discussionmentioning

confidence: 99%

Quantitative Evaluation of Nuclear Cataract Using Image Analysis

Sasaki¹,

Fujisawa²,

Sakamoto³

1992

To quantitatively evaluate nuclear lens opacification, we applied image analysis techniques. Utilizing a newly developed anterior eye segment analysis system, Scheimpflug slit images were taken in 65 eyes with transparent lenses and 31 eyes with nuclear cataract. In transparent lenses, scattering light intensity of the anterior fetal nucleus (AFN) was equal to or less than that of the posterior fetal nucleus (PFN). In eyes with nuclear cataract, scattering light intensity of the AFN was higher than that of the PFN. Utilizing this phenomenon, nuclear opacification was evaluated by the difference of scattering light intensity between the AFN and PFN (▵i value). The methodology applied in this investigation provides precise grading of nuclear cataract and progression thereof.