Yes, castor oil is good for cataracts because of moisture role. Your eyes will be moisture and are not dry. It is very good for your eyes. It is very helpful. You could also eat more food with vitamin C to moisture the eyes. You need to have the good rest. The surgery will be a good way to cure your cataracts which you may take for consideration.
Though there are many people treating cataracts with castor oil, no one has confirmed proof to say castor oil is of benefit to curing or reliving cataracts. Castor oil is often used as an eye lubricant to cure dry eyes. Anyway, it doesn't harm your eyes, so it's better for you to have a try than doing nothing at all.
There are many home made remedies for cataract, castor oil is one of them. You can put several drops of castor oil on your eyes before going to sleep. Castor oil has a high concentration of unsaturated fatty acids which are good for your eyes. Castor oil has been used as a remedy for thousand years. However, you can also use some other remedies for cataract. Instead of using castor oil, you can use unprocessed pure honey. Eating carrots is a popular natural remedy for cataract. If your cataract is in early stage, dusty miller can help dissolving the cataract.