In my opinion, and with some experience, ALL eye problems require a vet visit. Causes of sore, runny, dry, or itchy eyes can be varied and multiple. Do get your dog checked before taking any action. Several types of eye problem require very specific treatment and choosing the wrong drops can make the condition worse and in some cases cause irreparable harm.
If cost is a concern, or the condition ongoing or recurring, then your vet will tell you what your best home remedy options and vitally what ingredients to avoid. They have access to very good information about the active ingredients in most 'brand name' drugs to ensure you don't make a mistake. Clinagel is a prescription only medication and shouldn't be used for long term use. If your dog is still showing symptoms despite finishing a course of medication then it's safer (and in the long run probably less expensive) to take him back to your vet. Hope all is ok