Homozygous clones in the eye have smooth edges (in contrast to wild-type clones which have irregular edges due to cell mixing). Ommatidia within the mutant clones are often overrotated, although in general all eight photoreceptor cells are present and form trapezoid ommatidia (as in the wild type). Homozygous cells in the clones are larger than their wild-type neighbours. Cells within Tsc1^L115R clones in the eye imaginal disc are larger than adjacent wild-type cells. Tsc1^L115R clones in the eye disc show precocious differentiation of photoreceptors 1,6 and 7 and of non-neuronal cone cells. This appears to be an acceleration of the normal differentiation program rather than ectopic differentiation, as ectopic differentiation does not occur in clones anterior to the furrow. Specification of the R8 photoreceptor cell appears to be normal in the mutant clones. Ommatidial rotation is initiated precociously in clones in the eye disc.