In the suit for trademark infringement, permanent injunction can be passed for restraining the use of trademark or logo of plaintiff's on the defendant's product. However an order cannot be passed restraining the use of particular process for manufacturing the product.
From the prima facie, it comes to see that your client is using the trademark of plaintiff on the lenses. If it will get proved in the court, then the court can pass the injunction restraining the use of that particular trademark on the defendant's product and the products in stock bearing the same trademark will be seized.
But it does not in any manner restrain your client for using the process for manufacturing the lenses. Your client can still use the same process for preparation of lenses. He can opt for another logo on the product. The best way is to get his own trademark registerd in the trademark office.