When we speak of a symptom we refer to some abnormality in the tissue or the function of the eye, which may be perceptible to the patient himself, to an observer, or to both. We call it subjective when it is appreciable by the senses of the patient alone, objective when it can be perceived by another person. Pain, dizziness, and dimness of vision are subjective symptoms, while a swollen lid, a spot in the fundus, an abnormal tension of the eyeball, and a pulsation of either a blood vessel or of the eyeball are objective. Broadly speaking the findings of pathological, bacteriological, and biological findings are objective symptoms, because we gain a knowledge of them through the senses of others than the patient. With extremely rare exceptions a single symptom of either nature standing alone gives us no clue to the site or to the nature of the trouble which produced it, but simply indicates that something is wrong somewhere.
Occasionally we can demonstrate the presence of a subjective symptom of which the patient is unaware, as when we find a scotoma in the peripheral portion of the field, which may correspond to a lesion in the fundus, but evades his direct observation. The objective symptoms are learned through our own observation, and it is essential that we should cultivate this faculty to the utmost. We seat the patient in a darkened room with a light two or three feet away, in front of and a little to one side of his face, and focus the rays of this light upon the tissue we wish to examine with a +20 diopter lens, when all the details in the small illuminated area stand out very distinctly.
<Callout type="important" title="Critical Observation Skill">It is essential for an eye examiner to develop keen observational skills to detect even slight variations from normal conditions.</Callout>
If we need still more assistance we use a magnifying glass, or better a binocular loupe, in which magnifying glasses before the two eyes are adjusted so as to permit of stereoscopic vision of the enlarged image. In this way we can examine all parts of the cornea, anterior chamber, iris, and lens that are visible, and even the anterior portion of the vitreous without causing the patient any annoyance from the light.
Ophthalmoscopy is simply the inspection of the interior of the eye through an ophthalmoscope; so to complete the subject of inspection the method will be described here. The ophthalmoscope is simply an instrument that enables us to receive on our retina rays of light that are reflected from the funduses of our patients’ eyes. There are many patterns of the instrument, but the principle is the same in all, that the rays of light shall seem to pass from our own eye into the eye of the patient, so that they shall return into our own, in accordance with a law of physics.
<Callout type="gear" title="Essential Equipment">An ophthalmoscope and lenses are crucial for detailed examination of the fundus.</Callout>
This enables us to inspect such parts of the fundus as are not concealed behind other tissues. It is essential that the pupil should be dilated if we are to make such an inspection thoroughly because it is likely to contract as a reflex response to the entrance of the light, especially when the latter falls near or upon the macula.
Key Takeaways
- Understand and differentiate between subjective and objective symptoms in eye conditions.
- Master oblique illumination for detailed external eye examination without patient discomfort.
- Utilize ophthalmoscopy to inspect the interior of the eye, requiring pupil dilation.
Practical Tips
- Always ensure proper lighting when examining the eyes to avoid missing subtle details.
- Use a binocular loupe or magnifying glass for enhanced visibility during close-up inspection.
- Practice adjusting your position and instrument settings for optimal ophthalmoscope use.
Warnings & Risks
- Be cautious of photophobia in patients with eye lesions, as strong light can cause pain.
- Ensure the patient's cornea does not dry out when using cocaine or similar agents during examination.
Modern Application
While this chapter focuses on early 20th-century medical techniques for diagnosing ocular conditions, its emphasis on thorough symptom analysis and detailed eye inspection remains highly relevant today. Modern advancements in ophthalmology have refined these methods but the foundational principles of careful observation and differentiation between subjective and objective symptoms are still crucial.
Frequently Asked Questions
Q: What is the difference between subjective and objective ocular symptoms?
Subjective symptoms are those that can only be perceived by the patient, such as pain or dizziness. Objective symptoms, on the other hand, can be observed by another person, like a swollen lid or an abnormal tension of the eyeball.
Q: Why is oblique illumination preferred over direct lighting during eye examinations?
Oblique illumination provides clearer and more detailed views without causing discomfort to the patient. It concentrates light on a small area surrounded by darkness, making it easier to detect slight disturbances that might be missed under other conditions.
Q: What is the importance of pupil dilation during ophthalmoscopy?
Pupil dilation is essential for thorough inspection of the fundus as it prevents reflex contraction of the pupil and allows a more comprehensive view of the interior structures of the eye.