ULTRASOUND MEASUREMENTS OF THE DISTANCE BETWEEN LIMBUS AND RETINAL BREAK IN EYES WITH MEDIA OPACITIES

PURPOSE: To assess the reproducibility and accuracy of ultrasound (US) measurements in determining the distance between corneoscleral limbus and retinal break and its relation with the distance measured by indirect ophthalmoscopy, in patients undergoing a laser retinopexy procedure. METHODS: Forty-four patients with a single retinal break, scheduled for laser a retinopexy procedure (26 phakic patients and 18 pseudophakic patients), underwent 5 repeated measurements by high-resolution US and 3 measurements (at the time of the laser procedure, 1 and 3 months) by indirect ophthalmoscopy with scleral indentation of the corneoscleral limbus-retinal break distance with a caliper. RESULTS: In the phakic patients group, measurements ranged from 8.75 mm to 14.45 mm (12.56 ± 1.24, mean ± SD) and from 9.5 mm to 15 mm (12.35 ± 1.32) with US and indirect ophthalmoscopy, respectively. In the pseudophakic patients group, measurements ranged from 9.04 mm to 13.95 mm (11.88 ± 1.33) and from 8.5 mm to 13.2 mm (11.93 ± 0.99) with US and indirect ophthalmoscopy, respectively. The correlation coefficient was greater than 0.97. Measurement variability was very small. In phakic eyes, it was 0.13 ± 0.08 mm and 0.13 ± 0.07 mm with US and indirect ophthalmoscopy, respectively. In pseudophakic eyes, it was 0.12 ± 0.05 mm and 0.14 ± 0.05 mm with US and indirect ophthalmoscopy, respectively. US and indirect ophthalmoscopy measurements were not statistically different (Student's t-test, P = 1.71). The analysis of the variance among phakic and pseudophakic patients confirmed that measurements of the two groups do not differ significantly (Fisher's exact test, P = 0.16). The univariate analysis showed no significant difference in both US and indirect ophthalmoscopy measurements (ANOVA, P = 0.09) and between the two types of measurements and patient groups (ANOVA, P = 0.38). CONCLUSION: This study suggests relevant accuracy and reliability of US readings and provides the possibility of using this technique for localizing tears in eyes with media opacities by identifying the meridian and corneoscleral limbus-retinal break distance.