Hello 1.small nuclear fragments are harmless 2. If that fragment is in pupillary axis then only it can affect vision 3. In that case it is simple surgery with good prognosis

Well what are his complaints at present. Because large nuclear fragment tend to induce inflammation in the eye. And as you have mentioned its been 4 years now. Was he asymptomatic during these 4 years? Surgery is pretty atraumatic nowadays. Of course the size of nuclear fragment does decide further actions. If its more than 2mm and is causing secondary glaucoma and inflammation then one should go for the surgery.