English to French Medical Medical: Health Care

The evidence was limited to one nonrandomised controlled study of 29 patients, two very small case series (of six and three patients, respectively) and two case reports.In the controlled study, in which the dominant eye was operated on and the other eye served as a control, improvement in median reading acuity score at 20 cm was reported as –0.41 for operated eyes and –0.35 for control eyes (p < 0.03), indicating that the improvement in operated eyes was greater. No significant difference in reading acuity was found at 30 cm or 40 cm. One case series reported that near visual acuity improved temporarily in 3/8 eyes (38%), but it was no better than before surgery at day 360. In the same study, implanted bands were removed from three eyes upon patient request because of lack of benefit.

(Chirurgie de la presbytie par segments d’expansion sclérale)

mon pb vient du fait que je ne comprends pas sur quoi porte la comparaison :
l'amélioration de l'acuité visuelle de l'oeil opéré est 'supérieure' à l'amélioration de l'acuité visuelle de l'oeil témoin. Mais comment l'acuité visuelle peut-elle s'améliorer dans l'oeil témoin sans traitement ? La presbytie peut-elle s'améliorer spontanément ? Il y a qqchose que je ne saisis pas ici. Merci d'avance et bon dimanche !