Just reporting, "Visual" does not entitle a pilot on an IFR flight in controlled airspace to carry out a Visual Approach. There may be other conflicting aircraft in the vicinity e.g. the pilot stating he is "visual" may be number 3 or 4 or more in the actual approach sequence. He cannot 'jump the queue'.
For a Visual Approach Procedure In Controlled Airspace, ATC may clear an IFR flight a Visual Approach if
1. the pilot specifically states, "Request Visual Approach", and
2. the pilot must be able to maintain visual reference to the terrain, and
3. the reported ceiling is not below the approved initial approach level for the aircraft so cleared, or the pilot reports, at the initial approach level or at any time during the instrument approach procedure, that the meteorological conditions will permit a visual approach and that there is a reasonable assurance that the landing can be accomplished.
When cleared by ATC for a visual approach further descent is unrestricted except that ATC may impose further restriction or requirement included with the clearance. Any ATC altitude restriction remains in force until specifically cancelled.
An aircraft operating under IFR and making either a visual approach or a visual arrival procedure remains an IFR flight and is subject to ATC clearances for the purpose of providing separation. For example ATC may issue a clearance like, "Crudbuster 123 Cleared for Visual Approach. Follow B777 4nm final. Maintain 3000 feet. Contact XYZ Tower on 123.45."