OPHTHALMOLOGY • MARCH 1991 • VOLUME 98 • NUMBER 3

2. Jonas JB, Fernandez MC, Naumann GOH. Glaucomatous optic nerve atrophy in small discs with low cup-to-disc ratios. Ophthalmology 1990; 97 :1211 - 15.

3. Jonas JB. Biomorphometric des Nervus opticus. Bucherei des Au­genarztes, Stuttgart: Enke-Verlag, 1989; 81-3.

Detection of Wood Foreign Bodies

Dear Editor:

In a recent issue, Green et al reported on " Intraorbital Wood: Detection by Magnetic Resonance Imaging" (Ophthalmology 1990; 97:608-11). In their report, the authors use incorrect and inaccurate case documentation and literature reviews and, thus, arrive at conclusions that need to be challenged.

The authors present two cases with intraorbital wooden foreign bodies. One was managed in the Department of Ophthalmology at the Hospital for Sick Children in To­ronto, the other in the Department of Ophthalmology at the University oflowa in Iowa City. While the Toronto case was diagnosed with magnetic resonance imaging (MRI) only, the Iowa case was first diagnosed by Stan­dardized Ophthalmic Echography and then confirmed by MRI. However, the authors state in the abstract that the "wooden foreign bodies remained undetected after initial ophthalmologic examination and radiologic investigation which included plain orbital x-rays, orbital computed to­mography (CT) scans, and, in one case, orbital ultra­sound."

In the Discussion section, the authors quote the article by Reshef et al, 1 which reports the successful diagnosis and management of another wooden intraorbital foreign body in the Department of Ophthalmology at the Uni­versity of Iowa. In this case, again, standardized echog­raphy was the first method to identify the wooden orbital foreign body and was, in addition, crucial in the operating room by guiding the surgeon to the foreign body. Instead ofacknowledging this, the authors state that "ultrasound often does not detect orbital wood." The authors fail to acknowledge the well publicized considerable difference between (1) Standardized Ophthalmic Echography (com­bined use of standardized A-scan and B-scan), which is successfully used for the differentiation and localization of disease processes such as foreign bodies of any kind, not only in the eye, but in the orbit as well, and (2) the plain B-scan method, which, for good reasons, has lost considerable ground in orbital diagnosis since the advent of CT and MRI. By merging both echographic methods and treating them as "ultrasound" the authors mislead the reader by implying that the deficiencies ofB-scan apply for standardized echography as well.

Along the same line, in their conclusions, the authors do not concede any role whatsoever to ultrasound in gen­eral and to Standardized Ophthalmic Echography in par­ticular, a rather astonishing twist considering that in the one institution (Iowa), the two cases experienced in the last 15 years (the case described by Reshef et al 1 and one of the two cases presented by the authors themselves) were both first identified by standardized echography. Echog­

raphy certainly deserved to be considered as a method for detecting wooden intraorbital foreign bodies.

What the authors concluded, instead, clearly deserves objection. They stated, "the possibility of an intraorbital foreign body should be suspected in any patient sustaining minor lid trauma" (which is correct), and, "based on the role MRI scanning played in the management ofour two patients, we believe that it should be done in all cases where orbital penetration by a wooden foreign body is suspected. . . . " This latter statement, that an MRI be done in all suspicious cases (many ofthem certainly small children who require sedation or general anesthesia) is unreasonable. To follow the authors' suggestion would mean hundreds and thousands of negative MRis every year, which, considering the high cost of such a test and the already strained economy of our health care, consti­tutes an unacceptable waste. Standardized echography is a much less expensive test, which, if available, should be applied first. If this test is positive for or highly suggestive of a wooden foreign body, then the MRI should be used to confirm the diagnosis. If standardized echography is not available, a much stricter indication for an MRI should be required, such as prolonged inflammation and recurrent abscess formation or (as the authors suggest) radiologic detection of air within the orbit, rather than a vague suspicion or the mere fact that an injury has oc­curred.

Another dangerous aspect of the authors' conclusion is of medical legal nature: their report may easily be used to file charges for negligence against any physician who does not order an MRI in a case of even insignificant (peri) orbital injury.

KARL C. 0SSOINIG, MD Iowa City, Iowa

Reference

1. Reshef DS, Ossoinig KC, Nerad JA. Diagnosis and intraoperative localization of a deep orbital organic foreign body. Orbit 1987; 6:3­15.

Authors ' reply

Dear Editor:

We appreciate Dr. Ossoinig's comments, in which he supports the clinical usefulness of standardized echogra­phy in the localization of intraorbital foreign bodies. In fact, standardized echography was used in our case 2 to localize the wood fragment, and the study was performed by Dr. Ossoinig's echography service. However, we take issue with some statements he makes in his letter and the conclusions in his last paragraph.

First, we believe that ultrasound definitely has a place in the initial investigation of a suspected intraorbital for­eign body. We stated this clearly in the last sentence of the abstract of our article: "Investigation ofa case of sus­pected wooden foreign body in the orbit should include an MRI scan ifthere is no contraindication, and no foreign body has been defined on CT scan, ultrasound, or plain orbital films." 1 Furthermore, we emphasized this fact in

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