There was also in the early Classical period the possibility of using four movements, with a dance movement inserted before the slow movement, as in Haydns Piano sonatas No. 6 and No. 8. Mozarts sonatas were also primarily in three movements. Of the works that Haydn labelled piano sonata, divertimento, or partita in Hob XIV, seven are in two movements, thirty-five are in three, and three are in four; and there are several in three or four movements whose authenticity is listed as "doubtful." Composers such as Boccherini would publish sonatas for piano and obbligato instrument with an optional third movement—–in Boccherinis case, 28 cello sonatas. But increasingly instrumental works were laid out in four, not three movements, a practice seen first in string quartets and symphonies, and reaching the sonata proper in the early sonatas of Beethoven. However, two- and three-movement sonatas continued to be written throughout the Classical period: Beethovens opus 102 pair has a two-movement C major sonata and a three-movement D major sonata. Nevertheless, works with fewer or more than four movements were increasingly felt to be exceptions; they were labelled as having movements "omitted," or as having "extra" movements. Thus, the four-movement layout was by this point standard for the string quartet, and overwhelmingly the most common for the symphony. The usual order of the four movements was:

An allegro, which by this point was in what is called sonata form, complete with exposition, development, and recapitulation. A slow movement, an Andante, an Adagio or a Largo.
The ptosis is typically bilateral but may be unilateral for a period of months to years before the fellow lid becomes involved.Ophthalmoplegia (the inability or difficulty to move the eye) is usually symmetrical, therefore, patients are not affected by diplopia (double vision). The progressive ophthalmoplegia is often unnoticed till decreased ocular motility limits peripheral vision. Often someone else will point out the ocular disturbance to the patient. Patients will move their heads to adjust for the loss of peripheral vision caused by inability to abduct or adduct the eye. All directions of gaze are affected; however, downward gaze appears to be best spared. This is in contrast to progressive supranuclear palsy (PSP), which typically affects vertical gaze and spares horizontal gaze.Mitochondrial retinopathy has been described in CPEO which presents with a spectrum of distinct retinal phenotypes. This includes mild, focal pigmentary abnormalities on funduscopy and widespread granular pigmented fundus alterations. Mild, asymptomatic retinopathy might be underreported; severe retinopathy may be associated with significant vision loss. Occurring alongside CPEO
Weakness of extraocular muscle groups including, the orbicularis oculi muscle as well as facial and limb muscles may be present in up to 25% of patients with CPEO. As a result of the orbicularis oculi weakness, patients may suffer from exposure keratopathy (damage to cornea) from the inability to close the eyes tightly. Frontalis muscle weakness may exacerbate the ptotic lids with the inability to compensate for the ptosis.