This 13 year old dog is brought to you because the owners are concerned about the haziness in his lenses. He doesn’t seem to be having problems at the moment but should he have cataract surgery now to save his sight?
The key thing is not to look at the eye with incident light at an angle, as in that first image – in any older dog this will show scattered light from the ageing lens. Look, however, with an ophthalmoscope through the lens to view the reflected light from the tapetum as in this picture from the same dog. Note that there is no overt cataract here, just a ring marking the edge of the nucleus which has become compressed by the continually growing cortex and so has a higher refractive index but is still transparent. This is nuclear sclerosis which does not require cataract surgery.