Lens slitlamp image grading and nuclear hardness Purpose: To develop a lens nuclear grading system able to predict the hardness or surgical difficulty during cataract surgery. Methods: A 1 to 10 (plus 0) grading of the lens nuclear “density”, thus called BCN-10 was developed based on standardized clinical slit lamp photographs, from complete transparency (0) to a totally black cataract (10). The BCN-10 scale was tested for intra-observer and inter-observer repeatibility, for correlation with forward scattering measurement (C-Quant) and surgical difficulty (ultrasound time). Results: BCN-10 grading shows good intraobserver and interobserver repeatibility, good correlation with surgical ultrasound times and fair correlation with forward scattering (glare) measurements. Discussion: Available lens grading systems as the LOCS III do not include the harder grades of cataract, precisely where prediction would help the surgeons. BCN-10 is a novel and consistent lens nuclear grading system useful to predict the hardness and difficulty that will be encountered during cataract surgery, and to some extent correlates with cataract-induced glare disability.