Some ophthalmologists consider patients with convergence insufficiency to be dealt  by a psychiatrist. The improvement of the near point of convergence and fusional convergence amplitudes after appropriate therapy  puts convergence insufficiency on an innervational basis.  However, acquired convergence insufficiency may occur on an organic basis, such as subdural hematoma after sever head trauma.

Clinical Picture.

Patients who are suffering from convergence insufficiency complain of eyestrain and deep seated pain around the globes. After brief periods of reading, the letters will blur and run together; diplopia occasionally occurs during near work. Characteristically, one eye will be closed while reading to relief the visual fatigue and ocular headache is another frequent complaint.

Some authors believe that convergence insufficiency is caused by congenital weakness of the medial rectus muscles secondary to overaction of the lateral rectus muscle. 

DIAGNOSIS.

The diagnosis of convergence insufficiency is established by the finding of :

1) a remote near point of convergence and

2) decreased fusional convergence at near fixation.

 Convergence insufficiency becomes a real problem when the patient reaches the teenage years. Increased schoolwork and prolonged periods of reading increase the symptoms. The patient is usually a student who developes symptoms before examinations when increasing needs are made on the near vision during extended periods of studying. Symptoms are aggravated by lack of sleep, reduction of general well-being, and anxiety.

THERAPY.

Therapy for convergence insufficiency is the most successful application of orthoptic treatment and in most instances provides long-lasting relief from symptoms. As a rule, convergence insufficiency is a reversible condition and the decision to perform surgery should be made with extreme reluctance and not until all other therapeutic therapy, including prisms base-in, have been exhausted.

If surgery is inevitable,  resection of both medial rectus muscles is recommended. Overcorrection follows this procedure is common, and the patient has  to be warned to expect diplopia for several weeks postoperatively. The consecutive esotropia usually is greater at distance than at near fixation. If this occurs prisms are prescribed as upper segment bifocals to neutralize diplopia. Fortunately, the consecutive esotropia usually disappears spontaneously. Some suggested resecting the upper border and recessing the lower border of the medial rectus muscles to make the operation more effective at near than at distance fixation.