Immersion ultrasound biometry vs optical biometry.

PURPOSE: To compare axial length (AL) measurements obtained by optical biometry (OB) and immersion ultrasound (iUS) to investigate the agreement between the 2 techniques and how to use OB constants for eyes with AL by iUS. SETTING: Multicenter study. DESIGN: Retrospective observational case series. METHODS: Agreement between OB and iUS ALs was investigated in 4 subsets. Also, in a test database, the prediction error (PE) for iUS AL was assessed with 4 methods: (1) data-optimized constants; (2) user group for laser interference biometry (ULIB) constants with iUS biometry; (3) with recalibrated AL; and (4) ULIB A-constant - 0.23. RESULTS: A Combined 1970 eyes were measured with both OB and iUS biometry. OB mean AL was 0.0873 mm longer than iUS AL. The latter was made equivalent to OB ALs with this equation: Recalibrated iUS AL = 1.0228 × iUS AL - 0.4556. In a fifth database (n = 1079) with OB AL measurements only, after AL was artificially shortened by 0.0873 mm, the original A-constant had to be reduced by 0.23 to maintain a zero PE. In a sixth database (n = 127) with iUS AL, the original ULIB A-constant provided the poorest outcomes. Using either recalibrated iUS AL or ULIB A-constant - 0.23 zeroed out the mean PE and achieved the lowest median absolute error. CONCLUSIONS: AL measurements by iUS can be used with ULIB constants for OB by subtracting 0.23 from the A-constant; alternatively, the iUS AL may be recalibrated. The recalibrated iUS AL should be treated as AL measurements obtained by OB. It is longer than iUS AL in long eyes.

Comparing immersion ultrasound with partial coherence interferometry for intraocular lens power calculation.

BACKGROUND AND OBJECTIVE: To compare the utility and accuracy of high-precision immersion ultrasound, partial coherence interferometry, and the IOL Master system (Carl Zeiss Meditec, Dublin, CA) in a tertiary care referral center. PATIENTS AND METHODS: Comparative clinical study in a tertiary care, multispecialty, university practice. Participants were consecutive patients scheduled for cataract surgery at Emory Eye Center. Patients underwent biometry using immersion ultrasound, partial coherence interferometry, and the IOL Master system. RESULTS: Twenty-two percent of eyes undergoing surgery could not be measured using interferometry. In those eyes measurable by both methods, there was no difference in measurements nor postoperative refractive outcome. Each method had a high repeatability (intraclass correlation coefficient > 0.99) with a high intraclass correlation between methods (intraclass correlation coefficient = 0.99). CONCLUSIONS: When it can be used, interferometry is equivalent to immersion ultrasonography regarding biometric accuracy and precision. However, it cannot replace ultrasonography, especially for eyes with dense media opacity.

Clinicopathologic findings in choroidal melanomas after failed transpupillary thermotherapy.

PURPOSE: To review the clinicopathologic features of eyes enucleated after failed transpupillary thermotherapy. DESIGN: Retrospective review. METHODS: Pathology reports in the L.F. Montgomery Laboratory between 1998 and 2002 were searched for enucleated eyes with choroidal melanoma that had been treated only by transpupillary thermotherapy (TTT) prior to enucleation. The clinical features of the patients, including ultrasonography examination, were reviewed and compared with the pathologic findings. RESULTS: Seven eyes from seven patients had been enucleated, representing 8% of eyes treated with TTT at our institute during the period studied. The primary indication for enucleation was tumor growth. The melanomas tended to grow laterally, with minimal if any increase in thickness. Five of the seven eyes histologically demonstrated extrascleral extension, which was detected by ultrasonography prior to enucleation in only one of those eyes. CONCLUSIONS: Choroidal melanoma may continue to grow along a path of least resistance after TTT. The melanoma may extend laterally in the choroid and through emissary canals. Early extrascleral extension may be difficult to detect by ultrasonography.