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.

Retinal detachment with severe proliferative vitreoretinopathy in Terson syndrome

BACKGROUND

In several reports, early vitrectomy has been proposed for eyes with vitreous hemorrhage due to Terson syndrome as a means to hasten visual recovery. But the development of nuclear sclerosis and the neurologic problems arising from this disease encourage surgeons to wait for spontaneous resorption, especially with young patients. Although the formation of epiretinal membranes has been described, to the authors' knowledge retinal detachment with proliferative vitreoretinopathy in Terson syndrome never has been observed.

METHODS

The authors report five eyes from four patients with Terson syndrome due to spontaneous aneurysm rupture, in whom retinal detachment with proliferative vitreoretinopathy developed.

RESULTS

The early onset and the severe clinical course of proliferative vitreoretinopathy in these eyes showed parallels to traumatic proliferative vitreoretinopathy. The retina in all eyes could be reattached.

CONCLUSION

The authors point out the necessity for accurate and close follow-up and early, extensive surgical treatment in Terson syndrome, especially in patients with a reduced general state of health.

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

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-octyl-bromide (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.

Use of perfluorocarbon liquids in proliferative vitreoretinopathy: results and complications

BACKGROUND

The present study was set up to evaluate the influence of perfluorocarbon liquids on the postoperative anatomical and functional results as well as on the complication rates in eyes with proliferative vitreoretinopathy (PVR).

METHODS

Sixty five consecutive eyes (64 patients) with PVR in different stages requiring surgical intervention where liquid perfluorocarbons were used were compared with 64 consecutive eyes (62 patients) operated without the help of perfluorocarbon immediately before this time. Both groups were similar with regard to severity of PVR, number of operations, and initial visual acuity. The observation period was shorter in the perfluorocarbon group because they were operated more recently (17.4 months as against 24.4 months).

RESULTS

The anatomical as well as the functional success rates were not significantly higher in the perfluorocarbon group (69% v 61% and 65% v 53% respectively). However, in cases operated on without perfluorocarbons where reproliferation would occur it was of much greater severity than in cases where perfluorocarbons were used. The number of uncured cases with contraction of the retina at least in the inferior half was more than twice as high in the group operated on without perfluorocarbon. Combined with massive reproliferation secondary glaucoma and bullous or band keratopathy were more frequent in eyes treated before the use of perfluorocarbon.

CONCLUSION

The intraoperative use of perfluorocarbon liquids in vitreoretinal surgery does not prevent postoperative reproliferation but does reduce its severity.

Intraocular silicone lenses in silicone oil: an experimental study

BACKGROUND

To evaluate a potential effect of silicone oil on flexible silicone intraocular lenses, four lenses (STAAR AA-4203) were stored in silicone oil under sterile conditions for periods between 1 month and 3 years.

METHOD

The edge and surface of the lenses were examined by scanning electron micrography and the findings compared with a lens of the same model which had been stored in Ringer's solution for 2 years.

RESULTS

After 1 year of silicone oil exposure, droplets of different sizes adherent to the surface of the lens were found. These changes proceeded to a wave-like appearance of the surface after 2 and 3 years of storage, so that a continuous layer of silicone oil polymers is probably covering the intraocular lens.

CONCLUSION

Optical interference has to be considered a possibility if it turns out that the droplets cannot be removed during silicone oil evacuation. Consequently silicone intraocular lenses without hydrophilic preparation of the surface should not be implanted in eyes undergoing combined anterior and posterior segment surgery with silicone oil tamponade or in eyes with high risk for vitreoretinal complications.

Experimental vitreous and aqueous replacement with perfluorophenanthrene. Clinical, histologic, and electrophysiologic results

PURPOSE

Anterior and posterior segment changes of experimental vitreous and aqueous substitution with Perfluorophenanthrene were evaluated.

METHODS

In 28 rabbit eyes that underwent vitrectomy, tamponades of 1.2 cc Perfluorophenanthrene remained as long as 8 weeks under clinical and electrophysiologic control. Histologic examinations of the eyes were done 1, 2, 4, and 8 weeks after insertion of the tamponade. In an additional 15 rabbit eyes, Perfluorophenanthrene was injected into the anterior chamber, and in some cases it was removed after 2 and 4 weeks, respectively. Follow-up examinations, which were done no later than 12 weeks after injection, included clinical appearance, endothelial cell counts, corneal pachymetry, tonometry, and histopathology.

RESULTS

Histologically we found narrowing of the outer plexiform layer and single macrophages in the inferior retina after 2 weeks. Cell loss in the outer nuclear layer and wrinkling of the outer retinal layers were observed after 4 weeks, which lead to the development of irregularities of all layers inferiorly after 8 weeks. Electroretinograms showed unchanged b-wave amplitudes after maximal light stimulation at each examination, but separate interpretation of low light intensity responses showed a significant decrease in b-wave amplitudes 4 weeks after surgery. Anterior segment intolerance started with stromal edema on the second day after surgery; corneal vascularization and scar formation occurred subsequently. Inferior endothelial cell density decreased to about 50%. Histologically inflammatory reactions, vacuolization of the inferior trabecular meshwork, and closure of the chamber angle between 5 and 7 o'clock were observed.

CONCLUSIONS

Perfluorophenanthrene is only suitable for very short-term vitreous replacement unless prolapsing into the anterior chamber. Damages to the retina were observed 2 weeks after surgery.

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 keratoconus. 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%) eyes, 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiation therapy in proliferative vitreoretinopathy. A prospective randomized study

In a prospective study of the effect of postoperative radiation therapy for the prevention of reproliferation of membranes and recurrent proliferative vitreoretinopathy (PVR) two similar groups of patients with retinal detachment and PVR grade D1 to D3 in one eye were compared. Half the eyes (30) received a total dose of 3000 cGy after surgery; the other half remained untreated. After a follow-up of 6 months and 14 months or more (maximum 36 months) the anatomical and functional results of each group were compared. After 6 months in the unirradiated group 57% (17/30) remained attached and 43% (13/30) had detached again. In the irradiated group 63% (19/30) were attached and 37% (11/30) had detached. However, there was no statistically significant difference between the two groups (P = 0.479, Fisher's Exact Test). After 14 months the number of cured and uncured eyes remained the same in the unirradiated group, while in four of the eyes in the irradiated group a later onset of reproliferation and detachment occurred (after 7, 8, 12 and 14 months, respectively). A final cure rate of 57% (17/30) was achieved in the unirradiated group and a 50% (15/30) cure rate in the irradiated group. Thus the failure rate was 43% (13/30) in the unirradiated group and 50% (15/30) in the irradiated group (P = 0.473, Fisher's Exact Test). No side effects from the radiation were observed in any case and no radiation retinopathy occurred during an observation period of up to 3 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior segment changes in rabbits after experimental aqueous replacement with various amounts of different perfluorocarbon liquids

BACKGROUND

We evaluated biomicroscopic and histological effects on the anterior segment in the rabbit eye after temporary aqueous substitution with various amounts (0.2 cc and 0.025 cc) of perfluorodecaline (PFD) and perfluorophenanthrene (PFP).

METHODS

A quantity of 0.2 cc of the two perfluorocarbon (PFC) liquids was exchanged simultaneously with about 50% of the aqueous in 15 rabbit eyes each for periods of 1, 2, or 4 weeks. At these points some eyes were enucleated for histological examination. After 2 and 4 weeks the substances were removed from the remaining eyes, which were then followed up for 8-10 weeks. In an additional 8 eyes, 0.025 cc PFD or PFP was injected and left for 8 weeks. Four eyes received balanced salt solution and served as controls. Beside biomicroscopic evaluation and measurement of the intraocular pressure, endothelial cell counts and corneal pachymetry were performed regularly during follow-up.

RESULTS

The postoperative results were well comparable for PFD and PFP eyes. Within the first 2 weeks postoperatively corneal edema with endothelial cell loss was observed in both groups. Thereafter regression of the edema started independently of whether the substances were removed or not. IOP was not elevated at any time. At the end of follow-up central corneal thickness was the same as initially. In the inferior corneal endothelium cell density decreased to 45-50% of that in normals. Histologically, vacuoles in the iris and chamber angle were found inferiorly after 4 weeks. Chamber angle closures were present between 5 and 7 o'clock in those eyes where the PFC liquids had been removed after 2 and 4 weeks. Eyes with 0.025 cc PFD or PFP droplets showed vacuolization of the inferior trabecular meshwork 8 weeks postoperatively that was comparable with eyes which had a 50% aqueous replacement for 4 weeks. Control eyes remained unchanged in all aspects.

CONCLUSION

Anterior segment damage caused by PFC liquids is a contact-dependent effect seen in the early observation period. Experimentally there was no difference between the products used or between 2 and 4 weeks' duration of the tamponade.

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.

[Vitrectomy in uveitis]

Between January 1976 and December 1983, at the First University Eye Clinic in Vienna, 568 vitrectomies and 287 lensectomies were carried out; in 69 of these interventions (20 lensectomies and 49 vitrectomies) the diagnosis was uveitis. In 24 cases the indication for vitrectomy was an intermediary uveitis, a post-traumatic uveitis in 4 and a sympathetic uveitis in 6 cases as well as suppurative endophthalmitis in 7 patients. Indications for surgical removal of pathological tissue from the anterior chamber by the use of vitrectomy instrumentation were, in 4 cases each, hypopioniritis and a hemorrhagic uveitis, and in 12 cases a phacogenic uveitis. In about two thirds of this very heterogeneous patient material, employing vitrectomy made it possible to achieve regression of uveitis. In the remaining third of the patients, at least a stationary state of the disease was achieved and a reduction of corticosteroid and immunosuppressive therapy were made possible. The best functional results were achieved in all surgical interventions in the anterior ocular segment and in vitrectomies for intermediary uveitis. In suppurative endophthalmitis, however, these results were unfavorable.

Irradiation pretreatment before fibroblast implantation in experimental PVR

Fibroblast injection into the vitreous body causes traction detachment in the rabbit's 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.

Experimental perforating injury with high energy electrons to inhibit intraocular proliferation

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% fibronectin 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 post-operative 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.

Does vitrectomy followed by intraocular gas tamponade offer sufficiently effective treatment of retinal detachment due to holes in the posterior pole?

We report on 17 consecutive cases of retinal detachment due to macular hole surgically treated by one of the authors (S.B.) between the fall of 1982 and 1985. The standard method used was pars plana vitrectomy and intraocular air tamponade. In cases of subsequent reaccumulation of subretinal fluid, the macular hole was cautiously coagulated. With repeated redetachment and as a last resort, silicone oil was injected into the vitreous cavity. After a follow-up period ranging from 5 to 42 months, 13 of the 17 eyes were cured; in 2 aphakic eyes treatment remained unsuccessful; in 2 eyes a small central detachment with some accumulation of subretinal fluid persisted but did not progress. Vitrectomy and gas tamponade alone, without coagulation, constitute the safest and most sparing treatment of this type of retinal detachment. Unfortunately, approximately one half of these cases require subsequent additional photocoagulation because of renewed accumulation of subretinal fluid. In about one fourth of macular hole retinal detachments, however, lasting reattachment is achieved only by silicone oil tamponade following initial vitrectomy and air/gas tamponade.

[Differential diagnosis of papilledema]

Terminology, pathogenesis and differential diagnosis of papilloedema are discussed. A series of 100 consecutive patients with optic disc swelling is reviewed. Increased intracerebral pressure accounted for 32% of the cases. Vascular disease, such as central vein occlusion, central arterial occlusion and ischaemic neuropathy were the underlying diagnoses in the second largest group (22%) and in 18% of cases inflammatory disease caused the papillitis.