Graphic Raycaster with a bound check. For use on world space canvases to improve performance of raycasts. Make sure all your UI elements on within the bounds of the canvas and are co-planar.

GraphicRaycasterWithBoundsCheck.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class GraphicRaycasterWithBoundsCheck : GraphicRaycaster
{
    RectTransform _rectTransform;
    RectTransform RectTransform
    {
        get
        {
            if(!_rectTransform)
            {
                _rectTransform = GetComponent<RectTransform>();
            }
            return _rectTransform;
        }
    }

    public override void Raycast(PointerEventData eventData, List<RaycastResult> resultAppendList)
    {

        if (!RectTransformUtility.RectangleContainsScreenPoint(RectTransform, eventData.position, eventCamera))
            return;

        base.Raycast(eventData, resultAppendList);



    }
}