Peter Datlinger

Experimental long-term vitreous replacement with purified and nonpurified perfluorodecalin.

Highly purified perfluorodecalin and non-purified perfluorodecalin were injected into 34 rabbit eyes after mechanical vitrectomy, to evaluate the retinal tolerance in long-term vitreous replacement and the effect of purification on the retina. Unpurified perfluorodecalin caused severe inflammation and retinal damage and eight of ten eyes had developed retinal detachment after four weeks. In the eyes injected with highly purified perfluorodecalin, we observed retinal changes of the rod and cone, outer nuclear, and ganglion-cell layers after two weeks, which progressed to a thinning of all layers of the retina by the fourth week and to localized areas of retinal atrophy by the eighth week in the lower part of the eyes. Retinal damage in the upper part occurred after four weeks. At the perfluorocarbon-aqueous interface we observed a band of retinal necrosis that was noticed in all eyes four weeks postoperatively regardless of the substance used.

The effect of chemical stability and purification of perfluorocarbon liquids in experimental extended-term vitreous substitution

Abstract• Background: To determine the importance of chemical stability and purification of perfluorocarbon liquids (PFCLs) in experimental retinal tolerance, we tested four different substances as long-term vitreous tamponade: purified and nonpurified perfluorodecalin (PFD) and perfluoro-octylbromide (PFOB) • Method: After mechanical vitrectomy we replaced the vitreous of 65 rabbit eyes. Five groups were formed; four of them received the four PFCLs, while one served as control and received Ringer solution. The eyes were observed clinically every week and examined histologically after 1, 2, 4 and 8 weeks • Results: After 1 week we observed foam cells and intraretinal macrophages in all eyes with PFCLs. Purified PFD caused retinal lesions in the photoreceptor, ganglion cell and outer nuclear layers after only 2 weeks in the lower part of the eyes. In eyes filled with purified PFOB we observed more pronounced damage of the same nature. Unpurified substances caused severe inflammation and retinal detachment • Conclusion: Our study demonstrates that purification and chemical stability are important factors in retinal tolerance of PFCLs for vitreous replacement. Although purified PFD was tolerated by the rabbit eyes for 1 week, we cannot recommend this substance for short-term clinical use as a vitreous substitute.

Ocular findings in asymptomatic amateur boxers

A group of 25 active, asymptomatic, amateur boxers were examined to evaluate the nature and incidence of ocular pathologic conditions in amateur boxing. An approximately age-matched group of 25 men who were not boxers was used as a control group. The number of fights varied from 1 to 220 (mean 39.4), and the number of spar rounds from 20 to 600 (mean 192.5). Visual acuity was 20/20 in all subjects of both groups, except for one boxer with kerato-conus. Intraocular pressure was below 20 mmHg in all eyes. In 19 (76%) boxers, pathologic anatomic findings were attributed to contusion trauma. Lesions of the anterior eye segment included injuries of the lid in 3 eyes (12%), angle abnormalities in 5 (20%), and slight lens opacities in 5 (20%). Posterior vitreous detachment was observed in 3 (12%) boxers and peripheral retinal scars were seen in 15 (60%). In 6 (24%) 3eyes, retinal tears or atrophic holes were detected. In the 7 (28%) boxers with lesions of the anterior eye segment, the posterior segment was also affected in 6 (85%). In the control group, an atrophic hole was found in one (4%) patient with no other ocular pathologic findings. It is strongly recommended that the following conditions be implemented in amateur boxing: (1) the use of head gear and thumbless boxing gloves even for short spars; (2) the use of thumbless gloves instead of thumb-attached gloves; (3) the use of the sparring head gear for bouts; and (4) dilated retinal examination before beginning amateur career and periodic ophthalmologic examinations, including a dilated vitreoretinal examination, as a mandatory part of the license examination.

The antiproliferative effect of fractionized radiation therapy: Optimization of dosage

Fractionized radiation therapy with high-energy electrons have proven to reduce retinal detachment rate from 85% to 5% in the fibroblast model using a dosage of 3000 rad, starting from the first postoperative day. The purpose of this study is to gain more information about the therapeutic range of fractionized radiation therapy in experimental PVR. We therefore investigated the efficacy of this therapy when the total dose is reduced to 2000 rad. Irradiation treatment started on the first postoperative day. Eight weeks after cell implantation 5 of 14 eyes (35%) in the irradiated group and 15 of 16 eyes of the control group (93%) showed traction detachment. The statistically significant result proves a broad therapeutic range of fractionized radiation therapy in experimental PVR. We believe that a combination with antiinflammatory drugs could lead to a dose reduction in both therapies in patients.

Experimental perforating injury with high energy electrons to inhibit intraocular proliferation

Abstract. Since 1980, the fibroblast model creating experimental proliferative vitreoretinopathy has been used to evaluate the antiproliferative effect of various drugs. In previous studies radiation therapy was found to reduce effectively intraocular proliferation in this model. We therefore investigated the effect of high energy electrons in a standard perforating injury model creating a traumatic proliferative vitreoretinopathy. In 36 eyes we performed a 8 mm pars plana incision and injected 0.4 ml of 80% fibronection solution intravitreally. Ten rabbits (20 eyes) received radiation therapy with a Betatron accelerator in a total dosage of 3000 cGy to each eye divided into 10 single fractions starting on the first postoperative day. Maximum concentration of the dose was focused to the posterior vitreous. The other 9 rabbits, 18 eyes, served as control. In our perforating injury model we observed a reduction of retinal detachment rate of 72% in the controls to 55% in the treated group. The effect of radiation therapy with high energy electrons and total dosage of 3000 cGy was not statistically significant in experimental traumatic proliferative vitreoretinopathy.

Irradiation pretreatment before fibroblast implantation in experimental PVR.

Fibroblast injection into the vitreous body causes traction detachment in the rabbits eye. Various working groups reported different results on the main causes of the development of experimental PVR. These contradictions encouraged us to investigate the main source of experimental PVR by irradiating the ocular tissues before fibroblast implantation thus suppressing cell proliferation originating from host tissue. Over a period of 3 weeks, 22 eyes received ten radiations in a total dosage of 3000 rad. After the last radiation, 250,000 fibroblasts were implanted into 22 eyes. In another 4 eyes, fibroblast implantation but no radiation was carried out. After 8 weeks, 59% of 22 eyes developed different stages of retinal detachment. Comparison with the group of unirradiated eyes, which developed retinal detachment in 85%, revealed no significant differences in the number of detachments.