Summary
Diagnosing strabismus begins with a thorough history. The taking of a good medical history is an important acquired skill, which should not be relegated to ancillary personnel or questionnaires. This may include a review of old photographs and previous office and surgical records.
Observation of the patient during the history and subsequent examination is often critical to the acquisition of pertinent clinical information.
A well-performed sensorimotor exam is an acquired talent, which is especially important with children, who can easily become upset. Tricks to engage a child’s attention and gain cooperation are provided by Dr. Moody, who is an expert in the craft.
In-office prism adaptation and the “patch test” are useful techniques to help uncover deviations not immediately measured during the initial sensorimotor examination.
2 The History and Examination in Strabismus
“Data! Data! Data!” he cried impatiently. “I can’t make bricks without clay.” Sherlock Holmes—The Adventure of the Copper Beeches
Sir Arthur Conan Doyle
2.1 Gathering Data to Plan Strabismus Surgery
The surgical correction of strabismus must begin with a full gathering of data. At least 75% of medical diagnosis derives from the history, about 20% from the examination, and 5% or less through testing. There has been a tendency for modern ophthalmologists to overlook this principle due to time pressures, as well as possibly a lack of training. We relegate much of the history and part of the examination to technicians. The ophthalmologist touches briefly on the history, performs a partial examination, and then resorts to excessive nontargeted testing to search for a diagnosis. This costs the patient extra time and money and can result in a missed or incorrect diagnosis.
In strabismus, the alignment pattern alone is often assumed to be enough data with which to plan surgical correction, but it is inadequate for accurate treatment of complex cases. We often miss important elements of the history, and during the examination forget to check the fundus for torsion, which is critical to identifying pulley displacements and oblique muscle dysfunction.
The strabismologist should keep a blank and open mind regarding etiology and treatment until all the data are gathered, which includes careful observation during surgical exploration. Thinking methodically and open-mindedly, without hastily fixating on a single (and often false) diagnosis, results in better care of our patients and improved surgical outcomes.
2.2 Obtaining a Complete History
2.2.1 Introduction
The patient will usually tell you what is wrong, if you learn how to listen. This is especially true for strabismus, with its many layers of complexity.
During my residency at a major institution, there was a neurologist with a reputation of being able to figure out the most baffling cases. When the neurology service was stumped he would be called in for a consultation. Within 30 minutes of entering the patient’s room he would emerge, give his opinion, and recommend one or two tests. He was almost always correct. I had the good fortune to spend 3 months with this miracle doctor and learn his craft. He would pull up a chair next to the patient, ask questions, and listen. He would direct the conversation as needed and listen carefully to the answers. He also observed the patient throughout the history. By the time he began the examination, he had a good idea what to look for. After the exam only a small amount of targeted testing was needed to secure a diagnosis.
The examiner should keep an open mind regarding diagnosis until all the information is obtained. Targeted questioning will help to gradually cone down on the most likely diagnostic possibilities before the examination has begun. This is a skill that is honed by years of experience, and can be accelerated by direct observation of senior ophthalmologists as they practice their craft.
2.2.2 Children
2.2.2.1 Age and Time Course of Onset
Begin by asking the parents what they have been seeing, and exactly when it began. Try to pin them down on age of onset as precisely as possible. Many will say they saw strabismus at birth (Duane’s syndrome, craniofacial anomaly, etc.), but with prodding admit it was seen at several months of age (congenital esotropia and exotropia). Some parents will say the problem began sometime during infancy, but with more thought can pinpoint the onset to a specific age. They often forget about small traumas, which may prove to be significant and can happen at any time of life. An older child with a negative family history of strabismus who showed no strabismus until age 9 when he began to play football may have a very different pathology than another child of the same age with a strong family history and years of intermittent strabismus.
Was strabismus onset acute, subacute, or gradual? Is there intermittent control (suggesting fusional ability and an acquired process)? Is it worse when the child is tired (suggesting a larger underlying deviation with the need for prism adaptation, or myasthenia gravis)? Is it worse with visual effort (suggesting refractive error or nystagmus)? Acute onset could suggest an associated acute illness, neurologic event, or trauma. Subacute onset could indicate a progressive process, such as a rapidly enlarging mass, muscle displacement due to intermuscular band failure, or active inflammation. Gradual onset could suggest gradual muscle contracture, a slowly enlarging benign mass lesion, or gradually displacing muscle pulleys. There are obviously many more possible disorders than listed here, but the intention is to suggest a few that can be ruled out as the history progresses. A disorder that has gradually progressed over years cannot be due to an aggressive malignancy, so as questions are answered, the mental list of differential diagnoses shortens.
2.2.2.2 Associated Disorders, Family History
Was there coincident illness at the time of onset, which could suggest an inflammatory process? Does the child have unusual hyperflexibility, which could suggest collagen and pulley disorders?
Family history is also important. Try to have the parents specify the nature of any familial ophthalmologic disorders. A family history of “lazy eye” could mean ptosis, amblyopia, strabismus, or congenital cataract.
2.2.3 Adults
2.2.3.1 Onset of Strabismus
Much can be ruled out through the adult patient’s history of strabismus. Is there diplopia? If there is no diplopia, there may be a long-standing sensory disorder such as monofixation syndrome, which predisposed the patient to strabismus. When did it begin? The patient who develops acute strabismus due to a vascular event can usually pinpoint the onset fairly precisely. Was there a very gradual onset over a long period of time, subacute onset, or sudden onset? Patients with inflammatory etiologies can sometimes link stepwise worsening of symptoms to bouts of exacerbation of inflammation, such as sinusitis (Chapter 12, Chapter 13). Ask specifically about trauma to the head or face, and whether there was ever injury with ecchymosis (Chapter 20, Chapter 29).
The same questions about family history and associated illnesses apply to adults as well as children (above). The same diagnoses to consider in children regarding acute, subacute, and chronically progressive onset apply to adults as well, with a few additional adult-specific details. Prior strabismus and other ocular surgeries become more frequent, and systemic illnesses factor in more heavily. Remember to ask about prior myopia, as many adults have undergone cataract extraction and no longer wear glasses, despite having been profoundly myopic previously. Esotropia in an adult diabetic patient may not automatically be due to sixth cranial nerve palsy, even though some may be tempted to make that diagnosis without further thought. Myasthenia gravis should always be considered in cases of acquired strabismus, so questioning about variability, ptosis, and body weakness should be included. The history must be carefully thought through for each patient.
2.2.3.2 Review of Old Photographs
When the history of strabismus is unclear, review of old photographs from early childhood onward may be very helpful. A head tilt may have been present since early childhood, indicating a congenital abnormality, or may have been acquired later, suggesting trauma, inflammation, mass lesion, or other etiology. Exotropic patients often forget that the initial deviation before prior strabismus surgery was an esotropia, as demonstrated by early photos.
2.2.3.3 Prior Surgery
Many adult strabismus patients have already undergone previous strabismus surgery or other eye muscle–impacting ophthalmic surgeries prior to presenting in your office. It is very helpful to review prior operative reports whenever possible. Knowing where a muscle was placed and then observing its found attachment position provides a great deal of information about the healing in that patient. Scar migration (Chapter 5) cannot be diagnosed without the prior surgical records.
In complex cases with multiple prior strabismus surgeries, it is helpful to summarize each muscle procedure in a list or chart form. If office records are also available, the alignment response after each procedure provides important information in future planning. An example of this approach is described in the editor’s discussion of Mr. Watson’s essay at the front of this book.
2.2.3.4 Observation
“You see, but you do not observe. The distinction is clear.” Sherlock Holmes—A Scandal in Bohemia
Sir Arthur Conan Doyle
A valuable method of data gathering is to observe the patient during the history, as well as during the examination. Much can be learned by observation of details.
This author (IL) has experienced a number of cases in which observation led to timely diagnosis of potentially catastrophic conditions. Here are a few examples:
A young adolescent patient with well-controlled accommodative esotropia was undergoing her annual office visit. Neither she nor her mother had noticed any problems. During alignment testing at near, she reached with her left hand for the near vision stick, and it was observed that her right hand was held limply in her lap. When she was asked to switch to the right hand and she was able to hold the target, there was a slight tremor. This had never been noticed before in her, and therefore her mother was asked how long the arm had been weak. She had not been aware of it. Prompt referral for neurologic evaluation led to the early detection and complete excision and cure of a posterior fossa mass lesion. Her neurosurgeon was astonished and pleased by the early detection.
An elderly patient was referred for diplopia and strabismus, and had difficulty communicating the problem. She was brought by her caretaker, who was unaware of any history of dementia. A phone call to her physician son revealed that she did not suffer from dementia, so immediate referral was made to her internist, who found the new onset of diabetes and dangerously elevated blood glucose levels. She returned a few weeks later, with diabetic control, and had normal mental function, allowing the strabismus evaluation to resume.
A previously healthy teenaged girl presented to the hospital with acute diplopia and ptosis, and was diagnosed with complete right third cranial nerve palsy. She did not complain of marked pain. She was admitted by the neurology service and underwent a battery of tests and imaging studies. When she was presented to this author by the ophthalmology resident, her photophobia, pallor, and fatigued appearance led to the immediate diagnosis of migraine. This was confirmed after 2 days, when the cranial nerve palsy and all other symptoms resolved.
2.3 The Sensorimotor Examination in Strabismus Patients
2.3.1 Introduction
The goal of this section is to identify the most practical and valuable parts of the examination process in the pediatric and adult strabismus practice. It aims to address the proposition “What I wish I had known early in practice that has proven valuable to experienced doctors in the exam room.” Also, the purpose is not to create complete uniformity among fellow clinicians, but rather, to generate a creative bump among already expert clinicians. If the reader is prompted to rethink a procedure and upgrade it, this effort will have been worthwhile.
2.3.2 Use of Technicians
Most practices employ technicians, who can take or upgrade a past history and present illness, measure visual acuity and stereoacuity, check the peripheral fields by confrontation, and take a full-face photo. The photo is printed on a sheet of paper above a preprinted outline for analysis, with a space for the doctor’s initials. (All interpretations must be individually signed.) Regulations require the chief complaint to be personally obtained by the physician, to help insure it is recorded in the patient’s or family’s own words. Besides saving the doctor time, technicians also reassure and “warm up” the young patient, allowing a better exam by the physician. Upon repeating the visual acuity measurement, physicians often obtain a better acuity by one to three lines in a preschool child.
The examiner can check peripheral visual fields in a very young patien, by holding one light in each hand to each side of the child’s face simultaneously. The lights are alternately turned on, and the examiner watches for a glance to the lit side by the child. The examiner’s hands must be in place simultaneously on both sides of the face before the lights are turned on to prevent the examiner’s hand movement from evoking the head or eye turn. A helpful device to test confrontation fields in children is a thumb or fingertip light called D’Lite that is sold in magic stores. It is placed on the examiner’s thumb or forefinger and compressed by the opposing digit to light up the fake fingertip “magically.” Later in the exam, this same device can serve as a fixation target for eliciting rotations. Also, it is just fun, increasing rapport and cooperation.
A full-face photo is helpful to document lid levels; pupil size, shape, and color; facial configurations and anomalies; pseudoesotropia; strabismic deviation; fixation preference; and face turn. It is done as part of the check-in process for all patients. It can help prevent postoperative dissatisfaction. For example, parents may complain of a small ptosis after strabismus surgery. Referring back to the check-in photo will often reveal a subtle lid level difference, indicating that the lid difference was present before surgery and was not a surgical complication. Photos require interpretation and signature.
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