Andreas Wedrich

Dual-beam optical coherence tomography: signal identification for ophthalmologic diagnosis

The dual beam version of optical coherence topography can be used for noninvasive, high-resolution imaging of the human eye fundus, enabling in vivo visualization of retinal morphology as well as accurate quantification of the thickness profiles of its layers. Interferometric fundus signals-optical A-scans-and retinal tomograms of patients with glaucoma, diabetic retinopathy, and age-related macular degeneration are compared with those of healthy, normal subjects to elucidate the origin of the signal peaks detected and to investigate and interpret the retinal microstructures contained in the cross-sectional images.

Is there a correlation between the severity of diabetic retinopathy and keratoconjunctivitis sicca

Purpose. Patients with diabetic retinopathy (DRP) seldom report symptoms of ocular surface irritation, but evaluations of dryness are pathologic. This study was designed to evaluate the correlation between the severity of DRP and dry eyes. Methods. We included 144 eyes of 72 patients. Severity of retinopathy was graded according to the Early Treatment Diabetic Retinopathy Study. The examinations for dry eyes included Schirmers test, break-up time, lipid layer thickness, fluorescein and rose bengal staining of the cornea, impression cytology, and a questionnaire. A sicca severity score was calculated using a point system of the results of these tests. Patients were divided into three groups: postpanretinal laser coagulation (PPL), postcentral laser coagulation (PCL), and those with no laser treatment (0-L). For statistics, we used the correlation coefficient to determine relationships and the unpaired Student t test for statistical difference. Results. The correlation (c) of keratoconjunctivitis sicca (KCS) and DRP after laser treatment was c = 0.24 and after central laser treatment was c = 0.22; the correlation without laser treatment was 0.54. The best correlation is 1 or −1, the worst was 0. The score of those patients with mild to moderate retinopathy was compared to that of patients with severe to proliferative disease. There was a significant statistical difference in the sicca severity score between both groups, (p < 0.006, Student t test). Conclusion. KCS represents another manifestation of diabetes mellitus and its severity—measured by a many-membered score—correlates with the severity of the DRP.

Long-term results of combined trabeculectomy and small incision cataract surgery

Abstract We did a prospective study of 49 eyes (36 patients) with coexisting cataract and glaucoma who had combined trabeculectomy, phacoemulsification, and implantation of a folded polyHema intraocular lens through the trabeculectomy opening. Preoperatively, intraocular pressure (IOP) was controlled (< 20 mm Hg) in 13 eyes on a mean of 2.2 medications and uncontrolled (> 20 mm Hg) in 36 eyes on a mean of 2.4 medications. Preoperative visual acuity ranged from 20/40 to hand movements. At the end of the follow‐up, IOP was below 18 mm Hg in all eyes (100%), without therapy in 39 (80%) and with reduced therapy in 8 (16%). Two (4%) eyes were controlled on the same medication regimen. Visual acuity improved in 42 patients (86%); 38 (78%) achieved a visual acuity of 20/40 or better. A filtering bleb was observed in 45 eyes (92%). The most common early postoperative complication was fibrin exudation into the anterior chamber. Late complications included posterior synechias and vision‐impairing capsule opacifications. Visual acuity improved after neodymium:YAG laser treatment in all eyes with opacification without further complications. We conclude that the combination of small incision cataract surgery and trabeculectomy is a successful surgical approach for long‐term visual rehabilitation and glaucoma control.

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.

Twenty-three-gauge and 20-gauge vitrectomy in epiretinal membrane surgery.

Purpose: The purpose of this study was to investigate the safety profile of the 23-gauge sutureless vitrectomy system in the treatment of epiretinal membranes compared with standard 20-gauge vitrectomy. Methods: A retrospective case comparison of 20-gauge and 23-gauge vitrectomy performed in 167 and 64 eyes, respectively, by the same surgeon. Intraoperative and postoperative complications, duration of surgery, and postoperative visual acuity results were evaluated. Results: Postoperative hypotony occurred significantly more often in the 23-gauge group [9.4% (n = 6) vs. 0% (n = 0), P < 0.001]. With the 23-gauge system, the incidence of retinal detachment was 1.6% (n = 1), vitreous hemorrhage was 0%, and endophthalmitis was 1.6% (n = 1). Patients with 20-gauge vitrectomy developed retinal detachments in 1.8% (n = 3), vitreous hemorrhages in 1.2% (n = 2), and endophthalmitis in 2.4% (n = 4). The mean overall duration of surgery was significantly shorter in the 23-gauge procedures with 23.1 ± 6.5 minutes compared with 34.5 ± 9.1 minutes in the 20-gauge procedures (P < 0.05). At postoperative Day 2, patients with 23-gauge vitrectomy regained preoperative mean best-corrected visual acuity of 20/60. Patients who had 20-gauge vitrectomy experienced a statistically significant decrease of visual acuity from 20/80 to 20/100 (P < 0.05). Conclusion: Twenty-three-gauge vitrectomy in epiretinal membrane surgery is comparable with 20-gauge vitrectomy and is a safe method with a low complication rate. However, the incidence of postoperative hypotony is more frequent using the 23-gauge system.

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 haemodynamics and colour contrast sensitivity in patients with type 1 diabetes

BACKGROUND There is evidence that altered ocular blood flow is involved in the development and progression of diabetic retinopathy. However, the nature of these perfusion abnormalities is still a matter of controversy. Ocular haemodynamics were characterised with two recently introduced methods. METHODS The cross sectional study was performed in 59 patients with type 1 diabetes with a diabetes duration between 12 and 17 years and an age less than 32 years and a group of 25 age matched healthy controls. Scanning laser Doppler flowmetry and laser interferometric measurement of fundus pulsation amplitude were used to assess retinal and pulsatile choroidal blood flow, respectively. In addition, colour contrast sensitivity along the tritan axis was determined. RESULTS Fundus pulsation amplitude, but not retinal blood flow, increased with the progression of diabetic retinopathy. Retinal blood flow was influenced by plasma glucose levels (r = 0.32), whereas fundus pulsation amplitude was associated with HbA1c(r = 0.30). In addition, a negative correlation between the colour contrast sensitivity along the tritan axis and retinal blood flow was observed. CONCLUSIONS The present study indicates that pulsatile choroidal blood flow increases with the progression of diabetic retinopathy. Increased retinal blood flow appears to be related to loss of colour sensitivity in patents with type 1 diabetes.

Combined small-incision cataract surgery and trabeculectomy--technique and results.

In a prospective study 35 eyes of 25 patients with coexisting cataract and glaucoma underwent trabeculectomy, phacoemulsification and implantation of a folded polyHema intraocular lens through the trabeculectomy opening. Follow-up ranged from 6 to 27 months (mean 13.3). The mean age was 76.4 (68 to 88 years). 22 eyes suffered from primary open angle glaucoma, 10 eyes from a pseudoexfoliation glaucoma and 3 eyes had a chronic angle closure glaucoma. Preoperatively intraocular pressure was controlled in 10 eyes with a mean medication of 2.1 but uncontrolled in 25 eyes (mean medication: 2.5). The preoperative visual acuity ranged from 20/40 to hand motions. Postoperatively intraocular pressure was controlled (<18 mmHg) in all (100%) eyes and without therapy in 32 (91%) eyes. Three (9%) eyes had to be treated with topical timolol twice a day after surgery. Mean intraocular pressure dropped from 21.2±6.0 mmHg preoperatively to 13.5± 2.1 mmHg postoperatively. Vision improved in all but 4 eyes, 25 (74%) achieving a visual acuity of 20/40 or better. The causes for failed improvement or deterioration of vision were senile macular degeneration in 2 eyes and central retinal vein occlusion and vascular optic nerve atrophy in one eye respectively. Postoperative complications included hyphema in 9 (26%) eyes, fibrin effusion to a various extent into the anterior chamber in 19 (54%) eyes and delayed hypotony (<5 mmHg) with chorioidal effusion in 1 (3%) eye. Fibrin effusion was frequently observed in eyes with intraocular pressure below 10 mmHg, iris surgery and hyphema. Finally the complications did not effect the results regarding visual acuity or glaucoma control. In summary we conclude that the combination of small-incision cataract surgery and trabeculectomy is an effective surgical approach to obtain visual rehabilitation and glaucoma control with one single surgical intervention.

Intravitreal injection of tissue plasminogen activator and gas in subretinal hemorrhage caused by age-related macular degeneration.

Purpose: To assess the efficacy and safety of intravitreal injection of recombinant tissue plasminogen activator and sulfur hexaflucride gas for displacement of subretinal hemorrhages in patients with age‐related macular degeneration. Methods: The authors injected 25 μg of recombinant tissue plasminogen activator and 0.5 mL sulfur hexafluoride gas intravitreally in 11 patients with subretinal hemorrhages of less than 3 weeks duration. Anatomic and functional results were evaluated. Results: Displacement of subretinal blood was successful within the first week after surgery in 10 of 11 patients. This was accompanied by visual improvement in eight patients. After 1 year, visual acuity was better than before surgery in five patients. Diagnosis of a choroidal neovascularization by fluorescein angiography was possible in all patients, and was treated with laser photocoagulation in five. The authors observed no adverse effects of treatment. Conclusion: Recombinant tissue plasminogen activator and gas effectively displace subretinal blood in patients with age‐related macular degeneration. Randomized studies are necessary to prove the benefit of this simple and safe method in patients with subretinal hemorrhage due to age‐related macular degeneration.

Intracameral tissue plasminogen activator to treat severe fibrinous effusion after cataract surgery

Purpose: To evaluate the efficacy and complications of intracameral recombinant tissue plasminogen activator (r‐tPA) in the treatment of severe fibrinous effusion after cataract and combined cataract and glaucoma surgery. Setting: University Eye Hospital Vienna, Austria. Methods: In a prospective study, 40 eyes of 39 patients with severe fibrinous anterior chamber reaction in the early postoperative course received 25 µg r‐tPA intracamerally through a temporal paracentesis. The main outcome measures were rate of complete fibrinolysis, time of maximal effect, and complications. Results: Complete fibrinolysis occurred in 33 eyes (83%) after a mean of 3.2 hours ± 0.9 (SD). The rate of complete fibrinolysis was higher in eyes having cataract surgery only (24 eyes, 89%) than in those having combined surgery (9 eyes, 69%). Recurrent fibrin was seen in 3 eyes (7%), small anterior chamber hemorrhage in 7 (18%), increased intraocular pressure in 3 (7%), and posterior synechias in 13 (33%). Complications were managed conservatively. Conclusion: The intracameral injection of 25 µg r‐tPA proved to be a safe, efficient, and low‐risk supplement in the treatment of severe postoperative fibrinous reactions.