Background: Preoperative evaluation of lens opacity is used to predict surgical qualities of the lens and the expected improvement in visual acuity. The present study was conducted to ascertain whether preoperative clinical examination findings correlate with actual physical hardness of the lens and its histopathologic microstructure.
Methods: Two classification systems for clinical evaluation of lens opacity were compared: simple grading and the Lens Opacities Classification System II (LOCS II). Physical hardness of 65 lens nuclei extracted manually was measured using a specially designed hydrostatic guillotine. Lens material was then studied by low-magnification inspection of stained nuclei and by histologic examination.
Results: Multiple observers' simple grading of lens opacities was almost identical to a single observer's LOCS II evaluation. Hardness of the lens demonstrated high correlation with grading of nuclear sclerosis, but not with cortical or subcapsular opacities. Preoperative visual acuity correlated with lens hardness only in eyes with visual acuity less than 6/24. The lamellar structure of the lens is maintained also in dense nuclear cataract. We did not identify microscopic parameters that correlated with clinical appearance or hardness of the lenses.
Conclusions: Preoperative clinical examination of the eye provides reliable information that can be used to predict the physical qualities of the cataractous lens.