To assess the correlation between clinical cataract surgery indication and the objective scatter index (OSI) by defining the optimal OSI cutoff point in the surgery scheduling.Ophthalmology service, Consorcio Hospital General Universitario, Valencia, Spain.Prospective triple-masked randomized single-center study.Patients with cataractous eyes were recruited, and those with anterior segment disease, abnormal posterior pole, and/or previous ocular surgery were excluded. The principle of double-pass aberrometry was used by the main investigator to determine an OSI, after measuring subjective refraction and corrected distance visual acuity (CDVA), and then slitlamp evaluation was carried out by an independent researcher. The surgical decision was based on the current protocol according to the European guidelines. Correlation between the surgical decision, CDVA, and OSI were analyzed and an OSI discriminative value was calculated, implementing a receiver operating characteristic (ROC) curve.The study comprised 106 eyes (73 patients). The analysis established an inverse linear correlation between OSI and CDVA (r = -0.455, P < .0001). The comparison of the mean OSI between the surgical group (7.05 ± 4.65 [SD]) and the nonsurgical group (2.92 ± 1.88), revealed statistically significant differences (P = 5.04 × 10). The OSI score 3.2 was determined as the optimal cutoff value to discriminate surgical treatment (sensitivity 80%, specificity 84%).An optimal OSI value, according to an ROC curve calculation, was capable of providing clinicians with a powerful criterion for preoperative decision-making, thus suggesting an end to the subjectivity implicit in the cataract surgery decision-making process.