Sullivan, J. P., dissents in a memorandum as follows: I disagree with the majority only insofar as it affirms the denial of defendant Dr. Saary’s motion for summary judgment dismissing the complaint against him, since, in my view plaintiff has failed to demonstrate that there is a question of fact as to whether the infant plaintiff’s microphthalmia, a condition in which the eye and orbit are smaller than normal, and which, in the infant plaintiff’s case, has resulted in complete blindness in the left eye, was caused by the mother’s use of progesterone during the first trimester of pregnancy.
With respect to this question, the affidavit of defendant’s *182expert, Kwame Anyane-Yeboa, M.D., a physician board certified in the areas of clinical genetics and pediatrics, states that Dr. Yeboa’s "research of the medical literature discloses no statistically significant correlation between the use of progesterone in the first trimester of pregnancy and microphthalmia” and that while "[t]here are certain birth defects which have been associated with the mother’s use of progesterone in early pregnancy * * * [mjicrophthalmia * * * is not one of the anomalies which have been associated with progesterone. A correlation between the use of progesterone and microphthalmia has not been demonstrated.” Dr. Yeboa also stated that "microphthalmia is a recognized symptom of genetic disorder which has been identified as an autosomal recessive trait” and that "[alternatively * * * the appearance of microphthalmia * * * may represent a spontaneous genetic mutation.” In addition, the affidavit of Jesse H. Bidanset, Ph.D., a professor of pharmaceutical sciences and toxicology, states that "[tjhere is no scientifically proven correlation between the use of progesterone in the first trimester of pregnancy and the infant-plaintiffs congenital defect, microphthalmia”, and that "microphthalmia is not one of the defects which have been associated with progesterone use.”
The plaintiffs’ expert’s only statements relating to causation by the use of progesterone are that such use during pregnancy "has been associated with fetal malformations in cardiovascular, muscular, skeletal, organ and nervous systems and in the special senses (including the eyes)” and that "where [microphthalmia] is in only one eye and is not systemic, the defect is traced to impaired nutrition to the ovum, cause[d] by the progesterone.” While plaintiffs expert is a board-certified obstetrician and gynecologist, he does not purport to have any background or expertise in genetics or pharmacology. More significant, however, are the conclusory nature of his statements and the absence of any documentation of a causal connection between the use of progesterone during pregnancy and microphthalmia in the offspring. He is unable to cite a single authority, case report or other instance where progesterone has been linked to an ocular deficit. Indeed, FDA guidelines issued in 1989, prior to the time the drug was prescribed for plaintiff’s mother, require warnings only with respect to the possibility of genital malformations in connection with progesterone use in the first trimester. Thus, it is apparent that plaintiffs expert’s statements are nothing more than "conjecture and speculation^] which are no substitute for proof.” (Monahan v Weichert, 82 AD2d 102, 108.) As has often *183been stated, conclusory statements are insufficient to defeat a motion for summary judgment (see, e.g., West 90th Owners Corp. v Schlechter, 165 AD2d 46, 50, lv dismissed 77 NY2d 939); the opposing party must lay bare its proof and demonstrate material issues of fact (supra). All that plaintiffs have demonstrated is that they have found an expert who, without any basis therefor, is willing to offer an opinion contrary to the well documented prevailing wisdom. Such an opinion is worthless.
In the absence of any question of fact as to proximate cause, plaintiffs’ claim of malpractice based on Saary’s prescribing the drug, progesterone, should be dismissed. Contrary to the majority’s conclusion, this deficiency renders plaintiffs’ cause of action for lack of informed consent equally infirm. In order to establish a physician’s liability for failure to obtain a patient’s informed consent to a course of treatment, plaintiffs must prove that the treatment was the proximate cause of the injury. (See, Bernard v Block, 176 AD2d 843, 848; Public Health Law § 2805-d [3].)
Accordingly, I would grant defendant Saary’s motion for summary judgment dismissing the complaint.