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.

Culture plate temperature and delayed incubation effect on bacterial recovery.

PURPOSE: To discover if initial culturing conditions (plate temperature and time delay to incubation) adversely influence the recovery of organisms associated with bacterial keratitis. METHODS: The rate of temperature equilibration of culture plates taken from a refrigerator and placed in an incubator and left on the desk was evaluated with a digital thermometer. A standard inoculum for each of five organisms (S. aureus, S. pneumoniae, P. aeruginosa, E. aerogenes, K. oxytoca) isolated from human bacterial keratitis was spread evenly on blood agar plates at refrigerator (Tcold; 4 degrees C), room (Troom; 24 degrees C), and incubator (Twarm; 37 degrees C) temperatures. The plates were then kept at room temperature for 0, 1, 3, 5, and 8 hours before overnight incubation at 37 degrees C (S. pneumoniae under microaerophilic conditions), and the number of colony-forming units was counted. RESULTS: Cold plates took at least 15 minutes in an incubator to attain room temperature, and up to an hour when left on the desk. Increased organism recovery was found comparing both Twarm and Troom plates (6.2 to 24.8% and 7.0 to 14.7%, respectively, P<0.001) to Tcold plates for all organisms except S. pneumoniae (P=0.057). Comparing Twarm plates to Troom plates demonstrated an increased recovery (P<0.001) for S. aureus. Delayed incubation resulted in decreased recovery for S. pneumoniae (P<0.001). CONCLUSIONS: Culture plates should preferably be warmed at least to room temperature before inoculation, as well as promptly incubated to increase bacterial recovery from cases of septic keratitis.

A new, non-contact wide field viewing system for vitreous surgery.

PURPOSE: To report a new, noncontact wide field viewing system for vitreoretinal surgery. DESIGN: Device description: A noncontact wide field viewing system consisting of adjustable hinged arm and a combined condensing lens and reinverting prism has been developed. The arm clamps onto the operating table or wrist rest and holds the lens system in the air above the eye. METHODS: For vitreoretinal surgery, a new, relatively inexpensive noncontact wide field viewing system consisting of an adjustable hinged arm and a combined condensing lens and reinverting prism has been developed. The combination condensing lens and reinverting prism is used without a microscope-mounted inverter. The optical component may be sterilized with ethylene oxide, peracetic acid, or glutaraldehyde. Other components may be steam autoclaved. RESULTS: The new, noncontact wide field viewing system has been used satisfactorily in more than 200 vitrectomies at seven medical centers. It provides an excellent view of the vitreous and retina. CONCLUSION: A new, noncontact wide field viewing system for vitreoretinal surgery has been developed with satisfactory image quality and a field of view comparable to contemporary noncontact panoramic viewing systems.