— In a medical malpractice action to recover damages for personal injuries, etc., plaintiffs appeal, as limited by their brief, from so much of an order of the Supreme Court, Nassau County (Robbins, J.), entered November 10,1981, as, upon reargument of their motion for leave to serve an amended bill of particulars, in effect adhered to the original determination denying said motion. Order affirmed, insofar as appealed from, with costs. When an amendment to a pleading or a bill of particulars is sought at or on the eve of trial, judicial discretion in allowing such an amendment should be “ ‘discreet, circumspect, prudent and cautious’ ” (Smith v Sarkisian, 63 AD2d 780, 781, affd for reasons stated in mem at App Div 47 NY2d 878, quoting Symphonic Electronic Corp. v Audio Devices, 24 AD2d 746; Perricone v City of New York, 96 AD2d 531). Moreover, the addition of the new allegations of medical malpractice contained in plaintiffs’ proposed amended bill of particulars at a point in time remote from the original injury sustained in August, 1975 will result in substantial prejudice to defendant (see Loomis v Civetta Corinno Constr. Corp., 54 NY2d 18, 23). Plaintiffs have also failed to submit an affidavit from the physician who allegedly discovered these new acts of negligence, in order to present a reasonable excuse for the delay in asserting these claims and to explain their merit (see Perricone v City of New York, supra; De Rosa v Di Benedetto, 86 AD2d 648; Heinike Assoc, v Chile Lbr. Co., 83 AD2d 751; Walden v Nowinski, 63 AD2d 586). Gibbons, J. P., Bracken, Brown and Niehoff, JJ., concur.