Ultrasound biomicroscopy and corneal endothelium in Nd:YAG-laser iridotomy.

BACKGROUND AND OBJECTIVE: Thirty eyes affected by angle-closure glaucoma that had undergone YAG-laser iridotomy were studied to evaluate variations of central anterior chamber depth, width of the angle, and loss of endothelial cells after laser treatment. PATIENTS AND METHODS: These parameters were determined before and after iridotomy: endothelial cell count using a "non-contact" specular biomicroscope, and anterior chamber depth and angle width using ultrasound biomicroscopy (UBM). The width of the iridotomy and the distance of the iridotomy from the scleral spur and from the corneal endothelium were also measured by UBM, after laser treatment. RESULTS: Results confirmed that, after iridotomy, there is not a significant variation in the central depth of the anterior chamber: it goes from 2.02 mm pre-laser to 2.07 +/- 0.38 mm post-laser. There is, however, a statistically significant increase in the angle (P < .001), which goes from 10.69 +/- 8.88 degrees (0.109 +/- 0.07 mm) to 21.03 +/- 11.28 degrees (0.183 +/- 0.09 mm). The mean dimension of the iridotomies was 0.46 +/- 0.13 mm. The mean endothelial cell count was 55.8 +/- 4.08 cells per linear millimeter before laser treatment and 47.01 +/- 5.39 cells per linear millimeter afterward (P <.001). CONCLUSION: This study confirms that YAG-laser iridotomy leads to a reduction in the average endothelial cell density. The loss of these cells is inversely proportional to the distance of the iridotomy from the endothelium and the scleral spur.

Ultrasonographic findings in endophthalmitis.

Ultrasonographic findings are reported in 7 cases of endophthalmitis (6 of bacterial and 1 of fungal origin) resulting from perforating injuries (2 cases), severe corneal ulcers (2 cases) and open-eye surgery (3 cases). The most frequent ultrasonographic picture was characterized by a series of low reflectivity echoes in the vitreous with a high degree of mobility (7/7), fairly large endovitreal vacuoles (3/7) and hyaloid thickening (3/7). In one case the vitreous involvement was confined to only one quadrant. Choroidal thickening both of a homogeneous-diffuse (2/7) and nodular-multifocal type (3/7) was found. Localized choroidal detachment (1/7) and exudative pre-equatorial retinal detachment (1/7) were detected in only two cases. Ultrasonography proved useful both for detecting involvement of the posterior segment and for monitoring the time course of the infection process.

Apraclonidine protection of the blood-aqueous barrier from traumatic break-down.

This study investigated the effects of apraclonidine hydrochloride 1% eye drops on blood-aqueous barrier in 108 pigmented rabbits. The effects of pretreatment with dapiprazole and yohimbine, and a comparison with clonidine 0.125% eye drops are also reported. The disruption of blood-aqueous barrier was obtained by argon laser burning of the iris. The degree of permeability of the barrier was deduced by the amount of proteins in aqueous humor 60 min after laser application. Intraocular pressure and pupil diameter were also studied. Protein content in aqueous humor was 0.72 +/- 0.26 g/l in control rabbits that did not receive any treatment; 5.98 +/- 4.23 g/l in rabbits instilled with placebo eye drops and treated by laser burning of iris; 0.43 +/- 0.25 g/l in rabbits that received apraclonidine eye drops prior to laser burning; 2.19 +/- 1.3 g/l in rabbits that received apraclonidine eye drops immediately after laser application; 0.35 +/- 0.08 g/l in rabbits that received apraclonidine 1% eye drops both before and after laser application. Rabbits treated with clonidine 0.125% had a protein content in aqueous humor of 5.45 +/- 2.08 g/l after laser application. Dapiprazole 0.5% eye drops prior to apraclonidine led to a protein content in aqueous humor of 1.93 +/- 2.13 g/l; yohimbine 0.3% eye drops prior to apraclonidine led to a protein content of 0.70 +/- 0.40 g/l. Protein content in aqueous humor was 0.93 +/- 0.36 g/l, 0.82 +/- 0.899 g/l and 1.68 +/- 1.39 g/l in rabbits treated with yohimbine 0.3, 0.6 and 1.2 mg/kg i.v. and then with apraclonidine 1% eye drops. In one group of rabbits, the penetration into the aqueous humor of Evans blue injected intravenously was also studied. Evans blue content in aqueous humor was 0.03 +/- 0.08 mg/100 ml in control rabbits; 0.92 +/- 0.53 mg/100 ml in placebo rabbits treated by laser; and 0.28 +/- 0.19 mg/100 ml in apraclonidine rabbits treated by laser. Apraclonidine eye drops led to a decrease in IOP and prevented IOP rise following argon laser application. Placebo treated rabbits had a 20% increase in IOP following laser application. Apraclonidine-treated eyes showed mydriasis and blanching of the conjunctiva. These effects were not affected by pretreatment with dapiprazole or yohimbine. In these experiments, the treatment with apraclonidine 1% eye drops completely protected the blood aqueous barrier from the disruption caused by laser burning of the iris. The protection was less effective when apraclonidine was applied after laser burnings.