lower plane than the retina, is a coloboma of the choroid, which may or may not be associated with a coloboma of the sheath of the optic nerve. A very large, round or elliptical, depressed spot with a regular margin in the macula probably is a coloboma. All of these have to be differentiated from white spots that indicate pathological lesions of the choroid or retina.<Callout type="important" title="Important">Always differentiate between colobomas and other white spots for accurate diagnosis.</Callout> The Halo of the Papilla This is a more or less broad, complete or partial circle of a gray- ish, yellowish, or reddish color, immediately adjacent to the papilla, which fades away into the surrounding retina with no distinct mar- gin. The patient is elderly in nearly every case, and the halo may be due to senile, or to glaucomatous changes in the retina about the nerve head.<Callout type="warning" title="Warning">A halo around the papilla can indicate advanced glaucoma; seek immediate medical attention.</Callout> If any of the blood vessels hook over the margin of the papilla the halo is glaucomatous, and symptoms of a far ad- vanced glaucoma will be found in the eye; otherwise it is senile and has been caused by an atrophy of the choroid and of the pigment epithelium of the retina. The halo of the macula, which is to be seen in young people and has been described under the light reflexes of the fundus, is altogether different and of no pathological im- portance.<Callout type="tip" title="Tip">The halo around the papilla can help differentiate between senile changes and glaucoma.</Callout> Conus When the papilla presents on its temporal side a whitish crescent, or is surrounded by a ring that is broadest temporally, and this crescent or ring has a pigmented edge toward the retina, so that the general appearance is as though the pigment ring had been THE RETINA AND CHOROID 3859 pulled away from the scleral ring so as to leave some of the sclera exposed, we see what is called a conus. The choroid and the pig- ment epithelium of the retina over this area may be absent, or it may be rudimentary, so the color of the conus varies.<Callout type="risk" title="Risk">A conus can indicate an acquired myopia, which may progress to a posterior staphyloma.</Callout> A similar crescent is sometimes, though rarely, seen on the nasal, or the upper margin of the papilla, but when we see one below we have to deal with a different condition, that of an inferior conus. We are justified in pronouncing congenital a conus that is found in a healthy eye which is not myopic, and shows no tendency toward myopia, for in such a case the probability is that it is nothing more than an unusually broad scleral ring.<Callout type="beginner" title="Beginner">A conus can be congenital or acquired; both are important to differentiate.</Callout> Retinal vessels may pass over a conus, but an enlargement of the blind spot proves that the retina is not present in its entirety, aside from the absence of the pigment epithelium, as it has lost its func- tion. Except for the foreshortening mentioned the papilla usually appears to be normal, though it may be a little indistinct, or red- dened by contrast, perhaps by the foreshortening of its vessels.<Callout type="gear" title="Gear">A fundus camera is essential for accurate diagnosis and differentiation.</Callout> Posterior Staphyloma It is not right to say that the term conus should not be applied to the crescent found in myopia, or that a conus and a posterior 360 DIAGNOSIS FROM OCULAR SYMPTOMS staphyloma are the same,—the two conditions differ anatomically and in prognosis, though it is true that we are not able to differen- tiate them ophthalmoscopically in every case. A posterior staphy- loma is a localized outward bulging of the sclera, usually about the papilla.<Callout type="important" title="Important">A posterior staphyloma can be differentiated from a conus by its location and symptoms.</Callout> The crescent usually is broader than that of a conus, and sometimes we see in it gray or reddish gray curved lines, that impart a sort of terraced appearance when two or more are present, which are shadows cast by the margins of the staphyloma, and are diagnostic whenever they are seen. Ordinarily they appear only to the nasal side of the papilla, though occasionally they occur to the temporal side.<Callout type="tip" title="Tip">Look for Weiss-Otto shadow rings when diagnosing a posterior staphyloma.</Callout> Adam makes the statement, with some reservation, that the presence of sclerotic choroidal vessels in the crescent marks it as a posterior staphyloma, while their absence goes to show it to be a conus. If we happen to see in a case of myopia what looks like an ordinary conus, except that the choroidal vessels are visible within it, some perhaps obliterated while others may be full of blood, and reexamine it from time to time, we may be able to see this portion of the choroid pass through the stages of atrophy while the staphyloma grows larger and deeper, and the myopia increases.<Callout type="risk" title="Risk">Choroidal vessels within a conus can indicate progression to a posterior staphyloma.</Callout> If this is correct the presence or absence of the choroidal markings in what appears to be a myopic conus is a diag- nostic symptom of much value. The only other condition that would need to be differentiated would be a sclerosis of the choroid from some other cause, and this is not likely to be associated with a progressive myopia.<Callout type="warning" title="Warning">Sclerosis of the choroid can mimic a conus but does not progress.</Callout> Inferior Conus A white crescent that embraces the lower margin of the papilla is regarded generally as a rudimentary coloboma of the choroid. Dark spots may be scattered about in it, but the markings of the choroid cannot be traced.<Callout type="important" title="Important">An inferior conus can indicate a congenital defect and should be carefully evaluated.</Callout> The papilla is apt to be small, and obliquely or transversely elliptical, and often the line which divides it from the conus is far from distinct. It is apt also to be peculiar and anomalous both in its excavation, and in the distribution of its vessels.<Callout type="tip" title="Tip">Look for unusual characteristics when diagnosing an inferior conus.</Callout> The fundus almost invariably is albinotic in type in its lower part, even though it may be of a uniform red elsewhere. The eye is amblyopic and highly astigmatic, as a rule.<Callout type="warning" title="Warning">An inferior conus can cause significant visual impairment.</Callout> Coloboma of the Choroid Once in a while, usually though not always in connection with a coloboma of the iris, a brilliant white area is to be seen in the lower part of the fundus, which has a sharply defined, pigmented border, 362 DIAGNOSIS FROM OCULAR SYMPTOMS and is on a lower level than the retina. It may have the form of an ellipse, with its long axis vertical, lying between the papilla and the periphery, or it may have about the shape of a parabola with its vertex above, at, or below the papilla, its base lost in the periphery.<Callout type="important" title="Important">A coloboma of the choroid can be differentiated from other white spots by its location and appearance.</Callout> This is a coloboma of the choroid, a congenital defect supposed to be due to a faulty closure of the fetal cleft. Occasionally it is visible only when the patient looks far down, because it is so completely peripheral.<Callout type="tip" title="Tip">Look for a sharply defined border and location below the retina.</Callout> Although the general color is a shining, pearly white, portions of the coloboma may be pinkish, bluish, greenish, or gray, while brown or black spots are to be seen within it. The floor is quite uneven, as is shown by the play of light with the movements of the mirror, and the tortuous courses of the vessels that pass over it.<Callout type="warning" title="Warning">Uneven floors and tortuous vessels can indicate a coloboma.</Callout> The papilla is normal in most cases when it is not included in the coloboma. Its lower vessels may run freely over the surface of the latter on a level with the rest of the retina, and in such cases they can be shown by parallactic movements to be elevated above the floor of the defect, but more often the larger ones either turn aside at the margin of the coloboma and send small branches to ramify over its surface, or plunge over the margin with a distinct bend, and then wind about on a level plainly lower than that of the retina.<Callout type="important" title="Important">The location and appearance of vessels can help differentiate a coloboma from other conditions.</Callout> When the papilla is partially or wholly included in the coloboma we may find some difficulty in discerning its outline, but this can be distinguished usually. It is horizontally or obliquely elliptical in most cases, and the distribution of its vessels is abnormal.<Callout type="tip" title="Tip">Look for an abnormal vessel distribution when diagnosing a coloboma.</Callout> The characteristics manifested by the general appearance of the defect, by the retinal vessels, and in some cases by the papilla, serve to differentiate a congenital coloboma of the choroid from a white spot of similar size, shape, and position that might have been pro- duced by disease. In addition to this we are likely to find other malformations in the eye, for such a coloboma seldom occurs as the only congenital defect.<Callout type="warning" title="Warning">Colobomas often occur with other ocular defects.</Callout> Coloboma of the Macula A large, roundish, or transversely elliptical, white, or yellowish spot in the macula, which is depressed below the surface of the surrounding retina, is traversed by retinal vessels, sometimes con- tains a network of pigment, and has a regular, pigmented margin, possibly may be a coloboma of the macula, but as very few are on record all other white spots must be carefully excluded.<Callout type="important" title="Important">Carefully exclude other conditions when diagnosing a macular coloboma.</Callout> The defect is said to be confined to one eye, as a rule, but occasionally to be bilateral. The vision may range from normal to a high degree of amblyopia, but when it is good a scotoma is apt to be present.<Callout type="tip" title="Tip">Look for a scotoma in the presence of macular colobomas.</Callout> The conditions of which we must think when we see a large white spot in the macula are traumatic cedema of the retina, a coalescence of small white spots that are symptomatic of retinitis, circinate degeneration, tuberculosis, proliferating retinitis, occlusion of the central artery, amaurotic family idiocy if the patient is a child, a cyst, and central choroiditis, or sclerosis of the choroid.<Callout type="warning" title="Warning">A large white spot in the macula can indicate various conditions.</Callout> Most of these are excluded at once by the appearance and the history. A contusion of the eye followed by a dense grayish opacity of the retina, with practically normal vessels, that passed away in a few days, produced a traumatic cedema.<Callout type="important" title="Important">Traumatic cedema can be differentiated from other conditions based on appearance and history.</Callout> An irregular whitish mass with no pigmentation may be resolved into a coalescence of small white spots, but usually they are associated with well marked signs of a neuroretinitis; when such signs are absent it may indicate circinate degeneration if the patient is elderly, or a tubercle in a child, but in all of these the regularity of the margins of a coloboma is lacking.<Callout type="tip" title="Tip">Look for irregularities and absence of pigmentation to differentiate conditions.</Callout> The white mass of a proliferating retinitis is irregular, lies above the level of the retina, and is accompanied by signs of the preceding hemorrhage or inflammation. Both occlusion of the central artery and amaurotic family idiocy are marked by a red spot in the fovea; in the former there has been a sudden loss of vision, in the latter the child is growing more and more lethargic.<Callout type="warning" title="Warning">Amaurotic family idiocy can cause sudden vision loss.</Callout> A cyst is elevated, has no pigmented margin, and has a translucent appearance. The only conditions really productive of doubt are a central choroiditis, and a far advanced stage of sclerosis of the choroid in the macula.<Callout type="important" title="Important">Central choroiditis and advanced sclerotic changes can be difficult to differentiate.</Callout> The history is very important to the differentiation, for one of fail- ing vision, or of sudden blindness, excludes coloboma at once. If the eye is myopic, if it exhibits other changes that may be ascribed to traumatism, or to disease, and if the patient is elderly, syphilitic, tuberculous, or seriously ill with such a disease as diabetes, a pig- mented white spot in the macula probably marks a central choroi- ditis, and does so with certainty if the vision of the eye has been failing.<Callout type="tip" title="Tip">History can help differentiate between coloboma and other conditions.</Callout> A far advanced sclerosis of the choroid may be congenital, but such a condition is as uncommon as a coloboma, so we must be careful in asserting any distinctive marks to be in favor of either, and can be certain of only a few points.<Callout type="warning" title="Warning">Sclerosis of the choroid can mimic a coloboma.</Callout> Coloboma is stationary, while sclerosis is progressive, and it is possible to make the differ- entiation from accurate measurements made during a prolonged period of observation. When an adult is known to have had such a defect from early childhood and the eye to have kept the same vision since that time, whether it is good or amblyopic, the diagnosis of coloboma is practically positive.<Callout type="important" title="Important">A consistent history can confirm a coloboma.</Callout> When the history is unknown and the patient has good vision, we may be pretty sure that such a large white spot in the macula is a coloboma, but when his vision is poor, the diagnosis is doubtful.<Callout type="tip" title="Tip">Good vision can indicate a coloboma.</Callout> We notice in such a case the mar- gins and the markings of the floor of the spot, for an indented border without pigment and with visible sclerotic choroidal vessels would lead us to a diagnosis of sclerosis, while a regular, pigmented border with no definite choroidal markings in the floor would favor that of coloboma.<Callout type="warning" title="Warning">Indented borders can indicate sclerosis.</Callout> Other points that would be favorable to a diag- nosis of the latter are youth of the patient, and absence of any gen- eral disease that might cause sclerosis. Rupture of the Choroid When we see a long, narrow, white or yellowish, vertical crescent with sharply defined pigmented edges, across which the retinal ves- sels run, near the posterior pole of the fundus and concentric with the margin of the papilla, we infer that at some time the eye received a blow that produced a rupture of the choroid by contrecoup.<Callout type="important" title="Important">A vertical crescent can indicate a ruptured choroid.</Callout> Two or more ruptures may be nearly parallel. Usually they are of dif- ferent sizes and sometimes their margins are more or less jagged. It is very uncommon for us to see a rupture of the choroid on the nasal side of the papilla, though it has been known to occur, and another rare condition is such a horizontal rupture as has been por- trayed by Lawson.<Callout type="tip" title="Tip">Look for parallel ruptures when diagnosing a contrecoup injury.</Callout> A rupture of the choroid may be hidden by a hemorrhage imme- diately after the traumatism, but it stands out plainly when the blood has been absorbed. At first it may be yellowish, especially at the ends, but in most cases it becomes pure white later.<Callout type="warning" title="Warning">A rupture can be hidden by initial bleeding.</Callout> Little red spots are visible in it at times, and may be ascribed to
Key Takeaways
- Differentiate colobomas from other white spots for accurate diagnosis.
- Look for specific characteristics like the halo of the papilla to differentiate between senile and glaucomatous changes.
- Use a fundus camera for accurate differentiation between conditions affecting the retina and choroid.
- Carefully evaluate the history, appearance, and location of lesions when diagnosing retinal or choroidal conditions.
Practical Tips
- Always use a fundus camera to ensure accurate diagnosis and differentiation of retinal and choroidal conditions.
- Look for specific characteristics like the halo around the papilla to differentiate between senile changes and glaucoma.
- Carefully evaluate the history, appearance, and location of lesions when diagnosing retinal or choroidal conditions.
- Use a combination of clinical examination and patient history to rule out various ocular diseases.
- Keep in mind that some conditions like colobomas can be congenital while others may develop due to trauma.
Warnings & Risks
- A halo around the papilla can indicate advanced glaucoma; seek immediate medical attention.
- Uneven floors and tortuous vessels can indicate a coloboma, but other conditions can also present similar symptoms.
- A rupture of the choroid may be hidden by initial bleeding, so always check for signs of trauma even if no bleeding is visible immediately.
- Sclerosis of the choroid can mimic a coloboma but does not progress; careful differentiation is crucial.
Modern Application
While many of the historical techniques described in this chapter are now refined and improved upon through modern technology, the core principles of accurate diagnosis and differential diagnosis remain critical. A fundus camera, for instance, has replaced manual examination methods to provide clearer images. However, understanding these conditions is still essential for recognizing potential emergencies and ensuring timely medical intervention.
Frequently Asked Questions
Q: What are the key differences between a coloboma of the choroid and other white spots in the retina?
A coloboma of the choroid typically has a sharply defined, pigmented border and is located below the level of the retina. Other white spots may lack these characteristics and can be due to various conditions such as trauma or disease.
Q: How can one differentiate between senile changes and glaucoma based on the halo around the papilla?
The presence of a halo adjacent to the papilla, which fades into the surrounding retina with no distinct margin, is more likely due to senile changes. If blood vessels hook over the margin of the papilla, it suggests glaucomatous changes and requires immediate medical attention.
Q: What are the signs that a conus might indicate an acquired myopia?
A conus can be associated with an enlarged blind spot and may progress to a posterior staphyloma. The presence of choroidal vessels within the conus, especially if they show atrophy over time, is a sign of potential progression.
Q: How can one differentiate between a coloboma and other white spots in the macula?
Carefully evaluate the