Health Insurance Policies usually have Sub-Limits for some ailments like Cataracts. For Eg: if the Health Insurance Policy has a Sub-Limit of Rs50000 on a Sum Insured of Rs5 lakhs for Cataract, then this implies that the Insured Person can avail only Rs50000 towards Cataract Treatment. You should always check the various Sub-Limits before purchasing a Health Insurance Policy.