Investigating the temperature rise in porcine eye during femtosecond laser

Session Details

Session Title: LASIK Outcomes II

Session Date/Time: Tuesday 16/09/2014 | 14:00-16:00

Paper Time: 14:00

Venue: Capital Hall B

First Author: : R.Mencucci ITALY

Co Author(s): :    S. Matteoli   A. Virga   L. Terracciano   A. Corvi   R. Bellucci  

Abstract Details

Purpose:

Femtosecond cataract surgery offers several surgical advantages over conventional procedure, such as reduced phacoemulsification time, better wound architecture and a more stable refractive outcome. In contrast to the initial systems, which operate at repetition rates of a few kilohertz, newer systems have introduced progressive increases in laser-pulse emission frequencies of 30 kHz, 60 kHz, and 150 kHz, or even higher repetition rates.However, the increase in laser repetition rate is accompanied by an increase in average power incident onto the retina and iris, raising the potential for increased risk from thermal damage.Our study will investigate, using thermocouples placed at different depth levels, the temperature rise in porcine eye during direct illumination by the femtosecond laser as a model for laser exposure during cataract surgery.

Setting:

CEMS Verona

Methods:

Eighteen fresh porcine eyeballs underwent cataract surgery using femtosecond laser-assisted (VICTUS™ Femtosecond Laser Platform). The laser pulse rate and the fragmentation diameter were set to 80Hz and 7 mm, respectively. For femto-cataract procedure in human eyes the energy irradiated by laser depends on the type of cataract and the typical range is between 7000 nJ (refractive cataract) and 9000 nJ (very dense cataract). Therefore, the porcine eyes were divided into two equal groups (including each 9 eyes) to be treated with 7000 nJ or 9000 nJ. Before starting the surgical procedure a thermocouple was positioned by an expert surgeon inside the eyeball at three different depths (endothelium, anterior capsula and into the cataractous material). The temperature was recorded during the entire surgical procedure and the average of three measurements over different eyeballs was calculated.

Results:

The analysis of the temperature variation during cataract procedure showed that 1) the higher the energy of the laser, the higher the temperature variation at the three depths; 2) the maximum temperature variation corresponded to endothelium, regardless the energy; 3) the difference among the three depths is higher when 9000nJ are used.

Conclusions:

Our preliminary results showed that the corneal endothelium was the layer subjected to the highest temperature variation; as expected, the heating is proportional to the powers used and the temperature rise is very punctual, confined at the precise point where the laser is focused.

Financial Interest:

NONE