Change in major ocular biometry parameters axial length and keratometry in adults over time.

PURPOSE: To determine how much axial length (AL) and average keratometry (K) change over time in elderly patients and to assess clinical necessity of repeating biometry in instances where the second eye is operated on 6 months or more after the first. SETTING: Northwestern Memorial Hospital, Chicago, Illinois. DESIGN: Retrospective study. METHODS: Inclusion criteria were patients older than 35 years, with 2 biometry measurements over 6 months apart, measured with the IOL Master 700 from January 1, 2016, to September 15, 2020. Patients were excluded if they had any other intraocular surgery besides cataract. A linear mixed model and SPSS software was used to compare measurements among timepoints. RESULTS: 201 patients (402 eyes) were included (average age 73.3, 59.3% female). Average time between biometry measurements was 21.5 months (range 6 to 48 months). The mean change in AL was 0.04 mm (95% CI, 0.03 to 0.05, P = .10). The mean change in K was 0.01 diopters (95% CI, -0.10 to 0.30, P = .33). At the 6-month to 1-year interval (n = 73), mean change in AL was 0.04 mm. Mean change in AL did not significantly increase with greater time intervals. There was no correlation between time and ΔAL ( P = .70), nor between time and ΔK ( P = .98). CONCLUSIONS: In this cohort, biometric parameters did not change significantly over time. Repeating biometry at a 1- to 2-year interval for elderly patients receiving monofocal implants may offer limited benefit.

Comparison of the accuracy of subtraction CT angiography performed on 320-detector row volume CT with conventional CT angiography for diagnosis of intracranial aneurysms.

OBJECTIVE: The accuracy of diagnosis of intracranial aneurysms by subtraction computed tomography angiography (CTA) was compared with conventional non-subtracted CTA and with digital subtraction angiography (DSA). METHODS: 56 patients with spontaneous subarachnoid hemorrhage (SAH) and suspected intracranial aneurysms were evaluated from September 2009 to January 2010. All underwent 320-detector row volume CT-CTA examinations. Non-contrast CT of each patient's head with the same scan range was performed before the routine CTA scan as the mask image for subtraction. The subtraction CTA volume data was obtained by subtracting the mask image volume data from the conventional non-subtracted CTA volume data. Subtraction and conventional CTA volume data were transmitted to a VOXAR workstation and two physicians with experience in diagnostic imaging of the nervous system independently carried out image post-processing and judged the results. Neurosurgeons performed endovascular treatment or surgical clipping based on information available through the CTA alone. RESULTS: In 42 patients, 51 aneurysms were detected by DSA. On a per-aneurysm basis, the diagnostic sensitivity of subtraction CTA was 98.9% for physician 1 and 100% for physician 2. The sensitivity of conventional CTA was 93.7% for physician 1 and 92.6% for physician 2. There was excellent inter-observer agreement (κ=0.84, 95% confidence interval 0.82-0.85). The overall sensitivity, specificity, positive predictive and negative predictive values of subtraction CTA were all 100%. The overall sensitivity, specificity, positive predictive and negative predictive values of non-subtracted CTA were 94%, 100%, 100% and 76%, respectively. Therapeutic decisions could be made for all 42 patients based on subtraction CTA images, whereas conventional non-subtracted CTA provided sufficient information to make therapeutic decisions for only 35 patients. CONCLUSION: Conventional CTA has lower sensitivity for the detection of very small aneurysms and aneurysms adjacent to the skull when compared to subtraction CTA. Subtraction CTA performed on a 320-detector row volume CT is an accurate diagnostic tool that provides data equivalent to that obtained with three-dimensional-DSA for the detection of intracranial aneurysms.