Effectiveness and safety of femtosecond laser-assisted lens fragmentation and anterior capsulotomy versus the manual technique in cataract surgery.

PURPOSE: To evaluate the effectiveness and safety of cataract surgery using femtosecond laser-assisted lens fragmentation and anterior capsulotomy versus manual cataract surgery. SETTING: MaxiVision Eye Hospital, Begumpet, Hyderabad, India. DESIGN: Randomized controlled open-label multisurgeon prospective trial. METHODS: Patients (at least 18 years old) were randomized to femtosecond laser-assisted lens prefragmentation and capsulotomy or manual capsulorhexis and standard phacoemulsification. Measured outcomes were effective phacoemulsification time (EPT), surgeon-assessed ease of phacoemulsification, mean phaco energy, mean phaco time, balanced salt solution volume, capsulotomy precision, and adverse event rates. RESULTS: Fifty-six eyes had the femtosecond laser procedure, and 63 had manual cataract surgery. The mean EPT was significantly lower in the laser group (5.2 seconds ± 5.7 [SD]) than in the manual group (7.7 ± 6.0 seconds) (P=.025). There was a significant difference in the mean phaco energy between the 2 groups (13.8% ± 10.3% in laser group; 20.3% ± 8.1% in manual group) (P<.001). There were no significant between-group differences in the ease of phacoemulsification, mean phaco time, or balanced salt solution volume. Laser-assisted capsulotomies were significantly more accurate and precise (intended diameter, circularity, centration) (P<.01). The safety profiles of the procedures were equivalent, with no adverse events at the 1-day follow-up. CONCLUSION: The femtosecond laser platform was effective and safe in cataract surgery, reducing EPT and the mean phaco energy during lens fragmentation and providing precise and reproducible capsulotomies.

Noninvasive optoacoustic online retinal temperature determination during continuous-wave laser irradiation.

The therapeutic effect of most retinal laser treatments is initiated by a transient temperature increase. Although crucial to the effectiveness of the treatment, the temperature course is not exactly known due to individually different tissue properties. We develop an optoacoustic method to determine the retinal temperature increase in real time during continuous-wave (cw) laser irradiation, and perform temperature calculations to interpret the results exemplary for transpupillary thermotherapy (TTT). Porcine globes ex vivo and rabbit eyes in vivo are irradiated with a diode laser (lambda=810 nm, P< or =3 W, phi=2 mm) for 60 s. Simultaneously, pulses from a N2-laser pumped dye laser (lambda=500 nm, tau=3.5 ns, E approximately 5 microJ) are applied on the retina. Following its absorption, an ultrasonic pressure wave is emitted, which is detected by a transducer embedded in a contact lens. Using the previously measured temperature-dependent Gruneisen coefficient of chorioretinal tissue, a temperature raise in porcine eyes of 5.8 degrees C(Wcm2) after 60 s is observed and confirmed by simultaneous measurements with an inserted thermocouple. In a rabbit, we find 1.4 degrees C(Wcm2) with, and 2.2 degrees C(Wcm2) without perfusion at the same location. Coagulation of the rabbit's retina occurs at DeltaT=21 degrees C after 40 s. In conclusion, this optoacoustic method seems feasible for an in vivo real-time determination of temperature, opening the possibility for feedback control retinal laser treatments.