Ioannis K. Petropoulos

Idiopathic Macular Epiretinal Membrane Surgery and ILM Peeling: Anatomical and Functional Outcomes

Purpose: Evaluation of the visual and anatomical outcomes following idiopathic macular epiretinal membrane (ERM) removal, with or without internal limiting membrane (ILM) peeling, and review of the literature. Methods: A retrospective study of 39 eyes operated for idiopathic ERM was conducted. Pars plana vitrectomy was combined with ERM removal and Indocyanine green (ICG) assisted ILM peeling in 24 eyes. Results: In Group A (without ILM peeling), mean preoperative BCVA was 0.48 logMAR (0.3 in decimal units), whereas mean postoperative BCVA was 0.37 logMAR (0.4 in decimal units). In Group B (with ILM peeling), mean preoperative BCVA was 0.58 logMAR (0.25 in decimal units), whereas mean postoperative BCVA was 0.31 logMAR (0.5 in decimal units). No statistically significant difference was observed between Groups A and B regarding preoperative or postoperative BCVA (p>0.1, Student’s t-test). OCT measurement of postoperative foveal thickness reveled a significant decrease in thickness in both groups; however, no correlation was observed between postoperative BCVA and postoperative foveal thickness (Pearson’s correlation coefficient = 0.139; p>0.1). Conclusions: In spite of final visual acuity improvement following idiopathic ERM removal, recovery of a normal foveal thickness is not achieved in the majority of the cases. ICG assisted ILM peeling does not affect the functional outcome of idiopathic ERM removal.

Multiple Evanescent White Dot Syndrome Following Simultaneous Hepatitis-A and Yellow Fever Vaccination

Purpose: To report a case of multiple evanescent white dot syndrome (MEWDS) following simultaneous hepatitis-A virus (HAV) and yellow fever (YF) vaccination. Methods: Review of the clinical, laboratory, photographic, and angiographic records of a patient suffering from MEWDS. Results: A healthy 50-year-old woman presented with rapidly progressive left-eye visual loss, associated with photopsias and a para-central scotoma, one week after receiving simultaneous HAV and YF vaccination. Both anterior segments and right-eye fundus were unremarkable. Fundus examination of the left-eye disclosed papillitis with multiple, small, white, outer-retinal lesions. Angiographic tests were pathognomonic for MEWDS. Perimetry revealed left-eye blind spot enlargement. Initial inflammatory/infectious work-up was negative. Signs and symptoms resolved spontaneously within 6 weeks, with concomitant normalization of ancillary exams. Conclusions: The clinical presentation and the benign course were consistent with the diagnosis of MEWDS. No other aetiopathogenic factor than simultaneous HAV and YF immunization was identified, suggesting an autoimmune basis for MEWDS in predisposed patients.

Lactate-Induced Retinal Arteriolar Vasodilation Implicates Neuronal Nitric Oxide Synthesis in Minipigs

PURPOSE To investigate the role of neuronal nitric oxide (NO) synthesis in the retinal vasodilatory response to lactate in minipigs. METHODS Thirteen eyes of 13 minipigs were evaluated. Ten eyes received an intravenous infusion of N(omega)-nitro-L-arginine methyl ester (L-NAME). After 1 hour, the same eyes received an intravitreous juxta-arteriolar microinjection of 30 microL of L-lactate 0.5 M (pH 7.4) through a micropipette. Ten minutes later, 9 of 10 eyes received an intravitreous juxta-arteriolar microinjection of 30 microL of L-NAME 0.01 M (pH 7.4), and 1 received physiologic saline solution (PSS). The remaining three eyes received a microinjection of 30 microL of L-lactate 0.5 M (pH 7.4), without intravenous or intravitreous L-NAME. RESULTS The three eyes that received juxta-arteriolar injection of L-lactate only showed a reproducible increase in retinal arteriolar diameter that persisted during the entire study period (maximum effect at 20 minutes, 40.9% +/- 3.2%). Retinal arteriolar diameter decreased by 4.1% 1 hour after intravenous L-NAME when compared with baseline but the difference did not reach significance. The juxta-arteriolar injection of L-lactate induced a significant increase in retinal arteriolar diameter (22.7% and 28.7% at 5 and 10 minutes, respectively; P < 0.01), followed by a significant decrease (8.6%; P < 0.01) 10 minutes after juxta-arteriolar injection of L-NAME. Injection of PSS had no effect on retinal arteriolar diameter. CONCLUSIONS Juxta-arteriolar administration of L-lactate induced vasodilation, which was also observed with continuous intravenous infusion of L-NAME. Moreover, juxta-arteriolar L-NAME microinjection significantly suppressed the vasodilatory effect of L-lactate. These data suggest that neuronal-derived NO is an important mediator of lactate-induced vasodilation in minipigs.

The Vasodilatory Effect of Juxta-arteriolar Microinjection of EndothelinA Receptor Inhibitor in Healthy and Acute Branch Retinal Vein Occlusion Minipig Retinas

Purpose. To investigate the effect of the endothelin(A) receptor inhibitor BQ-123 on the retinal arteriolar vasculature in minipig retinas in normal eyes and eyes with acute branch retinal vein occlusion (BRVO). Methods. Seven healthy eyes of seven minipigs and six eyes of six minipigs with experimental BRVO were evaluated under systemic anesthesia. An intravitreal juxta-arteriolar microinjection of 30 microL BQ-123 0.61 microg/mL (pH 7.4) was performed in all but one eye from each group, into which the physiologic saline vehicle alone was injected. Vessel-diameter changes were measured with a retinal vessel analyzer. Results. In healthy minipig retinas (n = 6), arteriolar diameter (+/-SD) increased 6.19% +/- 3.55% (P < 0.05), 25.98% +/- 2.37% (P < 0.001), 23.65% +/- 1.2% (P < 0.001), and 16.84% +/- 1.95% (P < 0.001), at 1, 5, 10, and 15 minutes, respectively, after BQ-123 microinjection. Two hours after experimental BRVO (n = 5), the retinal arteriolar diameter had decreased (13.07% +/- 5.7%; P < 0.01). One, 5, 10, and 15 minutes after BQ-123 microinjection, retinal arteriolar diameter had increased by 7.14% +/- 3.3% (P < 0.01), 26.74% +/- 7.63% (P < 0.001), 23.67% +/- 6.4% (P < 0.001), and 16.09% +/- 3.41% (P < 0.001), respectively. Vehicle only injection had no vasoactive effect on physiologic or BRVO retinas. Conclusions. A significant increase in retinal arteriolar diameter was demonstrated after juxta-arteriolar BQ-123 microinjection in healthy and in acute BRVO minipig retinas. The results suggest a role for endothelin-1 in maintaining retinal basal arteriolar tone. Reversing the BRVO-related vasoconstriction by juxta-arteriolar BQ-123 microinjection could bring a new perspective to the management of BRVO.

Severe bilateral hypertensive retinopathy and optic neuropathy in a patient with pheochromocytoma.

BACKGROUND We present a case of severe bilateral hypertensive retinopathy and optic neuropathy due to pheochromocytoma. HISTORY AND SIGNS A 31-year-old woman presented with severe bilateral visual acuity loss associated with headaches and photophobia. Ophthalmoscopy showed bilateral optic disc edema, soft exudates, macular star, flame-shaped hemorrhages and arterial narrowing. The situation was more severe in the right eye. Fluorescein angiography confirmed the diagnosis of hypertensive retinopathy. Arterial blood pressure was 220/145 mmHg. A thorough systemic control revealed a right adrenal gland mass. Catecholamine secretion was normal. After ablation, the tumor proved to be a pheochromocytoma, and immunohistochemistry showed dopamine secretion. THERAPY AND OUTCOME Postoperative evolution was uncomplicated. Antihypertensive treatment lasted only a few months. Visual acuity was restored and the retinal alterations disappeared 8 months after surgery. CONCLUSIONS Severe hypertensive retinopathy with optic neuropathy may be a consequence of malignant hypertension due to a pheochromocytoma. It is reversible after ablation of the tumor. Early diagnosis is of vital importance and relies on hormonal investigation and immunohistochemistry.

The rationale of retinal endovascular fibrinolysis in the treatment of retinal vein occlusion: from experimental data to clinical application.

Purpose: We describe a retinal endovascular fibrinolysis technique to directly reperfuse experimentally occluded retinal veins using a simple micropipette. Methods: Retinal vein occlusion was photochemically induced in 12 eyes of 12 minipigs: after intravenous injection of 10% fluorescein (1-mL bolus), the targeted retinal vein segment was exposed to thrombin (50 units) and to Argon laser (100–200 mW) through a pars plana approach. A beveled micropipette with a 30-&mgr;m-diameter sharp edge was used for micropuncture of the occluded vein and endovascular microinjection of tissue plasminogen activator (50 &mgr;g/mL) in 11 eyes. In one control eye, balanced salt solution was injected. The lesion site was examined histologically. Results: Retinal vein occlusion was achieved in all cases. Endovascular microinjection of tissue plasminogen activator or balanced salt solution led to reperfusion of the occluded retinal vein in all cases. Indicative of successful reperfusion were the following: continuous endovascular flow, unaffected collateral circulation, no optic disk ischemia, and no venous wall bleeding. However, balanced salt solution injection was accompanied by thrombus formation at the punctured site, whereas no thrombus was observed with tissue plasminogen activator injection. Conclusion: Retinal endovascular fibrinolysis constitutes an efficient method of micropuncture and reperfusion of an experimentally occluded retinal vein. Thrombus formation at the punctured site can be prevented by injection of tissue plasminogen activator.

Congenital retinal macrovessels: description of three cases and review of the literature

BACKGROUND Congenital retinal macrovessels are large aberrant branches of retinal arteries or veins that cross the macula. We present three patients with a unilateral congenital retinal macrovessel and we conduct a review of the literature. PATIENTS AND METHODS A 22-year-old man complaining of chronic headache as well as two other men, 18 and 23 years old, respectively, during a routine ophthalmological examination, were found with a unilateral congenital retinal macrovessel each. A thorough ophthalmological examination was performed, including colour fundus photography in all three patients and fluorescein angiography in two of the patients. We followed them up for five years. THERAPY AND OUTCOME Investigation revealed a unilateral venous congenital retinal macrovessel in all patients. Clinical findings and visual acuity remained unchanged throughout the entire follow-up period. No complications were recorded. CONCLUSIONS Congenital retinal macrovessels are rare and they tend to remain stable. Visual acuity is preserved in most cases. Complications occur only occasionally and have been described in the literature. Differential diagnosis from other arteriovenous malformations affecting multiple organs is necessary.

Rétinopathie diabétique vasoproliférante : complications vitréorétiniennes et photocoagulation rétinienne incomplète

Introduction La panphotocoagulation retinienne s’est averee efficace dans la prevention des complications liees a une retinopathie diabetique vasoproliferante. La chirurgie est alors un acte de dernier recours, indispensable surtout en cas d’hematovitre persistant ou recidivant ou de decollement retinien. Nous tenterons de montrer que les yeux, dont les complications liees a une retinopathie diabetique vasoproliferante necessitent une sanction chirurgicale, sont souvent insuffisamment photocoagules. Patients et methodes Les protocoles operatoires et les resultats de la chirurgie vitreoretinienne d’une serie de 39 yeux de 36 patients atteints de complications liees a une retinopathie diabetique vasoproliferante ont ete analyses de maniere retrospective. Resultats L’âge moyen des sujets etait de 57 ans. Quatre-vingt-cinq pour cent des yeux avaient un hematovitre, 17 % un decollement retinien. Quatre-vingt-cinq pour cent avaient beneficie d’une photocoagulation retinienne pre-operatoire. Les operations ont consiste en une vitrectomie avec segmentation de membranes fibrovasculaires. Dans 85 % des yeux, la photocoagulation fut completee par endolaser, meme en peripherie moyenne. Le suivi post-operatoire etait de 39 ± 26 mois. Dans 97 % des yeux, une amelioration de l’etat anatomique de la retine et une amelioration ou stabilisation de l’acuite visuelle ont ete observees. Conclusion Ces resultats confirment les benefices de la chirurgie vitreoretinienne dans les complications liees a une retinopathie diabetique vasoproliferante. Surtout, il est a souligner que les complications aboutissant a une sanction chirurgicale sont souvent liees a une photocoagulation pre-operatoire incomplete. Pour etre efficace, la photocoagulation doit detruire plus de 35 % et jusqu’a 50 % des photorecepteurs. Un complement per-operatoire permet de limiter la reapparition de la proliferation fibrovasculaire.INTRODUCTION Panretinal photocoagulation proved to be effective in preventing complications related to vasoproliferative diabetic retinopathy. Surgery is most often a last resort in cases of recurrent or persistent vitreous hemorrhage or retinal detachment. The aim of our study is to point out that eyes requiring surgery for complications related to vasoproliferative diabetic retinopathy are often insufficiently photocoagulated. PATIENTS AND METHODS Retrospective analysis of operating protocols and surgical results for a series of 39 eyes of 36 patients with complications of vasoproliferative diabetic retinopathy. RESULTS The mean age at the intervention was 57 years. Eighty-five percent of the eyes had a vitreous hemorrhage, 17% a retinal detachment. Eighty-five percent of the eyes had undergone a partial retinal photocoagulation before surgery. All eyes underwent a vitrectomy with segmentation of fibrovascular membranes. In 85% of the eyes studied, endolaser photocoagulation was necessary, sometimes even in the mid-periphery. After 39+/-26 months of postoperative follow-up, 97% of eyes showed improvement of the anatomical state of the retina and improvement or stabilization of visual acuity. CONCLUSION Our results confirm the benefit of vitreoretinal surgery in complications related to vasoproliferative diabetic retinopathy. Moreover, it should be emphasized that complications requiring surgery often result from incomplete preoperative photocoagulation. To be effective, photocoagulation has to destroy more than 35% and up to 50% of photoreceptors. An intraoperative laser extension can reduce the risk of regrowth of fibrovascular membranes.

Preretinal partial pressure of oxygen gradients before and after experimental pars plana vitrectomy.

Purpose: To evaluate preretinal partial pressure of oxygen (PO2) gradients before and after experimental pars plana vitrectomy. Methods: Arteriolar, venous, and intervascular preretinal PO2 gradients were recorded in 7 minipigs during slow withdrawal of oxygen-sensitive microelectrodes (10-&mgr;m tip diameter) from the vitreoretinal interface to 2 mm into the vitreous cavity. Recordings were repeated after pars plana vitrectomy and balanced salt solution (BSS) intraocular perfusion. Results: Arteriolar, venous, and intervascular preretinal PO2 at the vitreoretinal interface were 62.3 ± 13.8, 22.5 ± 3.3, and 17.0 ± 7.5 mmHg, respectively, before vitrectomy; 97.7 ± 19.9, 40.0 ± 21.9, and 56.3 ± 28.4 mmHg, respectively, immediately after vitrectomy; and 59.0 ± 27.4, 25.2 ± 3.0, and 21.5 ± 4.5 mmHg, respectively, 2½ hours after interruption of BSS perfusion. PO2 2 mm from the vitreoretinal interface was 28.4 ± 3.6 mmHg before vitrectomy; 151.8 ± 4.5 mmHg immediately after vitrectomy; and 34.8 ± 4.1 mmHg 2½ hours after interruption of BSS perfusion. PO2 gradients were still present after vitrectomy, with the same patterns as before vitrectomy. Conclusion: Preretinal PO2 gradients are not eliminated after pars plana vitrectomy. During BSS perfusion, vitreous cavity PO2 is very high. Interruption of BSS perfusion evokes progressive equilibration of vitreous cavity PO2 with concomitant progressive return of preretinal PO2 gradients to their previtrectomy patterns. This indicates that preretinal diffusion of oxygen is not altered after vitrectomy. The beneficial effect of vitrectomy in ischemic retinal diseases or macular edema may be related to other mechanisms, such as increased oxygen convection currents or removal of growth factors and cytokines secreted in the vitreous.

Vasomotor effect of intravitreal juxta-arteriolar injection of L-lactate on the retinal arterioles after acute branch retinal vein occlusion in minipigs.

PURPOSE To investigate the effect of L-lactate on retinal arteriolar diameter after acute branch retinal vein occlusion (BRVO) in minipigs. METHODS Thirteen eyes of 13 minipigs were evaluated, with the animals under general anesthesia. BRVO was induced by a standard method of argon laser endophotocoagulation. Two hours after BRVO, an intravitreal, juxta-arteriolar microinjection of 50 μL L-lactate 0.5 M (pH 7.4) was performed in nine eyes. Four eyes received a microinjection of 50 μL of the solvent (pH 7.4) that was used to prepare the solution of L-lactate and served as controls. Retinal arteriolar diameter changes were measured using a retinal vessel analyzer. RESULTS Overall (n = 13), 2 hours after BRVO, there was a 9.0% ± 1.4% decrease in the retinal arteriolar diameter in the affected ares compared to baseline (P < 0.001). An increase of 26.2% ± 8.2% (P = 0.004) of the arteriolar diameter was evidenced 5 minutes after L-lactate juxta-arteriolar microinjection (n = 9) compared with the diameter before L-lactate microinjection. Thereafter, the vasodilatory effect of L-lactate persisted and remained significant until the end of the study period (27.7% ± 7.8% at 30 minutes) compared with the diameter before L-lactate microinjection (P = 0.002). Microinjection of the solvent alone (n = 4) did not produce any significant effect on the retinal arterioles, which remained constricted at all time-points (P > 0.1). CONCLUSIONS These findings demonstrate a significant arteriolar vasodilation after intravitreal juxta-arteriolar L-lactate microinjection in eyes with experimental BRVO in the affected areas. L-lactate microinjection can reverse the arteriolar vasoconstriction that occurs in acute experimental BRVO.