The effect of YAG laser iridotomy on the blood aqueous barrier in the rabbit.

The effect of YAG laser iridotomy on the blood aqueous barrier in the rabbit was investigated in 21 eyes. In seven series, each containing three pigmented rabbits, the right eye received a YAG laser iridotomy in the upper nasal quadrant of the peripheral iris under standardized conditions utilizing the Mikroruptor II (Lasag Company, Thun/Switzerland). One of the parameters describing the blood aqueous barrier effects was the intraocular pressure, which was monitored at 10 min intervals. The iridotomy caused significant pressure increases in the treated eyes which was maintained up to 90 min following the laser procedure. The measurement of the protein concentration and the lactate dehydrogenase activity was done at equal time intervals after the iridotomy, on the basis of anterior chamber tapping of the treated eyes and the untreated control eyes. Over a period of 100 min after laser surgery, a positive correlation between time and protein concentration for the treated eyes (r = + 0.86) could be established. The activity of the enzyme lactate dehydrogenase in the treated eyes was increased within 5 min of the trauma, reaching a maximum 45 min after surgery, and the increase in activity level remained 150 min after surgery. The results indicate that the disturbance of the blood aqueous barrier with the YAG laser is not essentially different from that of the argon laser, although tissue damage may be more pronounced.