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

Abstract

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.

Correlation of lens density measured using the Pentacam Scheimpflug system with the Lens Opacities Classification System III grading score and visual acuity in age-related nuclear cataract

“…Foo and Maclean20 reported that the peak value and mean value of the lens density with Nidek EAS-1000 were able to present changes over a 6-month period in nuclear cataract but not in cortical or PSC cataract. Although the peak value of lens density was evaluated at one point of the entire lens nucleus, it may be considered as a representative index of the whole nucleus because, according to West and Taylor,21 NO is likely to be homogenous, and it is reasonable to suppose that visual impairment in nuclear cataract patients is most likely dependent on the opacity of the central nucleus rather than mean opacity.…”

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

“…Although photographic image analysis densitometry, [14][15][16][17] or digital image analysis [18][19][20] as it becomes more widespread, might provide some more objective measures to enhance our preoperative assessment of cataracts and facilitate studies on progression of lens opacities, 21 the LOCSIII and other cataract grading systems have been shown to have high inter-observer and intra-observer repeatability 13,18,[22][23][24] and to demonstrate some consistency between different classifications. [24][25][26][27] New techniques such as photon spectroscopy for in vivo analysis of lenses remain to be further investigated.…”

External factors in the development of cataract

“…Implementing Scheimpflug and retroillumination digital photography with computerised analysis of lens opacities has allowed progression of cataract to be measured with great precision. [71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88] This method, cost effective for the large epidemiological studies, 89 is probably the best technique for recording cataract changes.…”