Retinal colour duplex scanning during LASIK-ring suction with different keratomes.

PURPOSE: The purpose was to measure the blood flow velocity during the suction phase of LASIK. SETTING: University Eye Hospital, Martin-Luther-University Halle-Wittenberg, Halle, Germany. METHODS: Papillary blood flow velocity was measured by colour Doppler sonography. Suction rings of four different manufacturers were applied in 30 healthy volunteers without eye diseases all of normal blood and eye pressure. The velocity of the blood flow in the central retinal artery was measured before, during and after suction. RESULTS: When Hansatome (Bausch & Lomb) and M2 (Moria) rings were used, no blood flow velocity was detected during suction in 90% of all cases. These rings were compared to the SKBM standard suction ring (Alcon) and the Krumeich non-IOP ring, in which no blood was present in only 56.67% (p < 0.05) and 10% (p < 0.001) of cases respectively. Moria, Alcon and Krumeich Lasitome rings performed equally well during the recovery phase compared with the original values. An exception is the Hansatome ring (Bausch & Lomb), with lower velocities when evaluated after 30 minutes (p < 0.01). CONCLUSIONS: During the ring suction phase of LASIK, the rings tested reduce velocity differently.

[Retinal color Doppler scanning of arteria centralis retinae by retinal diseases and healthy people]. / Farbduplexsonografie der Arteria centralis retinae bei retinalen Erkrankungen und bei Gesunden.

BACKGROUND: The purpose of the study was to analyse retinal vascular diseases, a frequent reason for the sudden loss of vision, with the help of duplex Doppler ultrasonography as a non-invasive procedure, and to reproduce the results known from the literature using a common clinical device, thus allowing for an inexpensive out-patient examination. METHOD: 50 volunteers without eye diseases and with normal blood pressure, 8 patients with central retinal artery occlusion, and 24 patients with central retinal vein occlusion were examined. The study was conducted for the first time with a common device, a duplex Doppler unit (EccOcee SSA 340 A; Toshiba) using a 7 MHz microconvex array transducer. RESULTS: The observed peak velocity was 10.41 +/- 2 cm/s in normal subjects and therefore statistically significantly lower compared to patients with central retinal artery occlusion (6.5 +/- 1.2 cm/s) and those with central retinal vein occlusion (8.4 +/- 1.7 cm/s). The end diastolic velocity was also significantly lower in both groups of patients. With a lower statistical level of significance, it was also found that the second eye of patients with retinal vascular diseases shows a lower peak velocity in comparison to the control persons. CONCLUSIONS: We have examined the haemodynamics of the eye with respect to the blood flow velocity in the central retinal artery while trying to keep the other influencing factors neutral. The measured velocity is in accordance with the results known from the literature. We have thus confirmed that the blood flow in the central retinal vessels can be measured also with a less powerful device. Being simple, our method can easily be reproduced and is perfectly suited for measuring the systolic/diastolic flow at the optic nerve. Our observation of a generally lower flow velocity in cases of known high-risk patients whose second eye shows a retinal occlusion suggests that therapeutic consequences and prognoses can be derived whenever duplex Doppler ultrasonography yields abnormally low values.