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Introduction: Since July 2021, a worldwide shortage of verteporfin (Visudyne (R)) occurred: an essential medicine required for photodynamic therapy (PDT). PDT with verteporfin has a broad range of indications in ophthalmology, including chronic central serous chorioretinopathy, polypoidal choroidal vasculopathy and choroidal haemangioma. For these disorders, PDT is either the first-choice treatment or regarded as a major treatment option. Materials and methods: A questionnaire was sent to key opinion leaders in the field of medical retina throughout the world, to assess the role of PDT in their country and the effects of the shortage of verteporfin. In addition, information on the application of alternative treatments during shortage of verteporfin was obtained, to further assess the impact of the shortage. Results: Our questionnaire indicated that the shortage of verteporfin had a major impact on ophthalmic care worldwide and was regarded to be a serious problem by most of our respondents. However, even though there is ample evidence to support the use of PDT in several chorioretinal diseases, we found notable differences in its use in normal patient care throughout the world. Various alternative management strategies were noted during the verteporfin shortage, including lowering the dose of verteporfin per patient, the use of alternative treatment strategies and the use of a centralized system for allocating the remaining ampoules of verteporfin in some countries. Conclusion: The shortage of verteporfin has had a large effect on the care of ophthalmic patients across the world and may have resulted in significant and irreversible vision loss. Mitigation strategies should be developed in consultation with all stakeholders to avoid future medication shortages of verteporfin and other unique ophthalmic medications. These strategies may include mandatory stock keeping, compulsory licensing to an alternative manufacturer or incentivizing the development of competition, for example through novel public-private partnerships.

Wolfram syndrome 1 (WFS1, OMIM 222300), a rare genetic disorder characterized by optic nerve atrophy, deafness, diabetes insipidus and diabetes mellitus, is caused by mutations of WFS1, encoding WFS1/wolframin. Non-syndromic WFS1 variants are associated with the risk of diabetes mellitus due to altered function of wolframin in pancreatic islet cells, expanding the importance of wolframin. This study extends a previous report for the monkey retina, using immunohistochemistry to localize wolframin on cryostat and paraffin sections of human retina. In addition, the human retinal pigment epithelial (RPE) cell line termed ARPE-19 and retinas from both pigmented and albino mice were studied to assess wolframin localization. In the human retina, wolframin was expressed in retinal ganglion cells, optic axons and the proximal optic nerve. Wolframin expression in the human retinal pigment epithelium (RPE) was confirmed with intense cytoplasmic labeling in ARPE-19 cells. Strong labeling of the RPE was also found in the albino mouse retina. Cryostat sections of the mouse retina showed a more extended pattern of wolframin labeling, including the inner nuclear layer (INL) and photoreceptor inner segments, confirming the recent report of Kawano et al. [Kawano, J., Tanizawa, Y., Shinoda, K., 2008. Wolfram syndrome 1 (Wfs1) gene expression in the normal mouse visual system. J. Comp. Neurol. 510, 1-23]. Absence of these cells in the human specimens despite the use of human-specific antibodies to wolframin may be related to delayed fixation. Loss of wolframin function in RGCs and the unmyelinated portion of retinal axons could explain optic nerve atrophy in Wolfram Syndrome 1.

Purpose To determine the effect of duration of macular detachment (DMD) on visual acuity (VA) in patients with macula-off rhegmatogenous retinal detachment (RD). Design Retrospective observational case series. Participants Two hundred two consecutive patients (202 eyes) with primary uncomplicated macula-off RD, preoperative VA of 10/100 or worse, a precise history of when macular function was lost, successful reattachment surgery, and a minimal follow-up of 3 months. Intervention All RDs were repaired with a primary scleral buckling procedure performed by 3 vitreoretinal surgeons. Main Outcome Measure Visual acuity (best corrected and 3, 6, and 12 months postoperatively). Results Considering all eyes, the cumulative mean of the best-corrected postoperative VA (logarithm of the minimum angle of resolution [logMAR]) as a function of DMD shows a rapid worsening when DMD exceeds 6 days. Eyes were divided into 3 groups, corresponding to the DMD intervals immediate (within 10 days), delayed (11 days–6 weeks), and late (>6 weeks). Mean postoperative VAs (in logMAR) were 0.35±0.31 (between 20/40 and 20/50 Snellen equivalent) in eyes with DMD up to 10 days, 0.48±0.26 (20/60 Snellen equivalent) in the delayed group, and 0.86±0.30 (8/60 Snellen equivalent) in eyes with DMD longer than 6 weeks. Conclusions The cumulative mean of the best-corrected postoperative VA (logMAR) as a function of DMD shows a rapid worsening when DMD exceeds 6 days. Our results indicate that the scleral buckling procedure should be done preferably within a 7-day DMD.

Background/Aims: Cyclic 3′,5′-guanosine monophosphate (cGMP), a central molecule in the phototransduction cascade, is also involved in a number of other physiological processes in the retina, like stimulating the absorption of subretinal fluid by activating the retinal pigment epithelium (RPE) cell pump. The aim of this study was to quantify cGMP synthesis by RPE cells and to investigate the role of two separate enzymatic pathways (soluble versus particulate guanylyl cyclase) in its production. Methods: cGMP expression was evaluated by immunochemistry and radioimmunoassay following culture of the D407 RPE cell line in the presence of a nonselective phosphodiesterase inhibitor (IBMX), in combination with the particulate guanylyl cyclase stimulator atrial natriuretic peptide (ANP) or the soluble guanylyl cyclase stimulator sodium nitroprusside (SNP). Results: Stimulation of the particulate guanylyl cyclase in RPE cells with ANP resulted in high intra- and extracellular cGMP levels. Stimulation of the soluble guanylyl cyclase by SNP resulted in a slight elevation of cGMP levels compared to controls. Conclusions: These results show that cultured human RPE cells are capable of producing cGMP and that most cGMP is generated following stimulation of the particulate guanylyl cyclase pathway.

BACKGROUND: Nitric oxide (NO) plays a significant role in physiological and pathological processes in the retina. In the L-arginine-NO pathway, NO synthase (NOS) converts L-arginine to NO and L-citrulline. Increased NO production, mediated by inducible NOS has been implicated in the pathogenesis of various vitreoretinal diseases. In the present study it is hypothesized that in rhegmatogenous retinal detachment (RRD), the production of NO pathway metabolites might be upregulated. METHODS: Using high-pressure liquid chromatography citrulline, arginine and nitrite were measured in vitreous fluid of 93 eyes with RRD, nine eyes with a traction retinal detachment due to proliferative diabetic retinopathy (PDR), and in 49 control samples of vitreous fluid from eyes without retinal detachment. RESULTS: The mean vitreous concentrations of citrulline and arginine were significantly increased in eyes with RRD (9.6+/-4.3 and 97.3+/-29.2; respectively) or in eyes with a traction retinal detachment (25.8+/-10.3 and 130.7+/-23.7; respectively) as compared to control eyes (7.1+/-3.2 and 75.9+/-18.1; respectively). The mean level of nitrite was also higher in vitreous fluid of patients with RRD (2.24+/-1.4) or patients with a traction retinal detachment (2.21+/-0.72) than in the controls (2.01+/-0.72), although not significantly so. CONCLUSIONS: We found increased levels of NO pathway metabolites in the vitreous fluid of eyes with retinal detachment, which may reflect a possible role of NO in the pathogenesis of this disease.

Experimental models have implicated glutamate in the irreversible damage to retinal cells following retinal detachment. In this retrospective study we investigated a possible role for glutamate and other amino acid neurotransmitters during clinical rhegmatogenous retinal detachment (RRD). Undiluted vitreous samples were obtained from 176 patients undergoing pars plana vitrectomy. The study group consisted of 114 patients (114 eyes) with a rhegmatogenous retinal detachment. Controls included 52 eyes with an idiopathic macular hole or idiopathic epiretinal membrane and 10 eyes with a traction retinal detachment due to proliferative diabetic retinopathy. Vitreous concentrations of glutamate, gamma-aminobutyric acid (GABA), taurine, glycine, and aspartate were determined by high-pressure liquid chromatography (HPLC). Multivariate analysis was used to examine a possible association between amino acid neurotransmitter levels and several clinical variables including visual acuity. The mean vitreous concentration of glutamate in eyes with a rhegmatogenous retinal detachment (16.6 +/- 5.6 microM) was significantly higher as compared to the controls (13.1 +/- 5.2 microM) (P = 0.001). Taurine levels were also increased in RRD, whereas no significant difference could be observed in glycine, aspartate and GABA levels when comparing RRD with controls. A correlation was found between increased vitreous glutamate and a lower pre-operative visual acuity. No association was, however, observed between post-operative visual acuity and the level of any of the five amino acid neurotransmitters. RRD was associated with a significantly increased vitreous glutamate concentration. Using visual acuity as a functional parameter in this study, we could not demonstrate a correlation between vitreous glutamate, or any of the other tested amino acid neurotransmitters and visual outcome.

PURPOSE. Transforming growth factor (TGF)-beta2 and hepatocyte growth factor (HGF) have been implicated in the pathogenesis of proliferative vitreoretinopathy (PVR) after retinal detachment surgery. The exact role of these factors in the early events, immediately after primary retinal detachment, is not yet known, and determining their roles was therefore the purpose of this study. METHODS. Subretinal fluids were collected prospectively from 144 patients during surgery for scleral buckling. TGF-beta2 and HGF were measured with commercially available ELISA kits. Thirty patients in whom a redetachment caused by postoperative PVR developed, were compared with 114 patients with an uncomplicated retinal detachment. The controls included 18 vitreous samples from patients with macular hole or pucker. Multivariate regression analysis was used to compare the relative roles of growth factors and clinical factors in the development of PVR. RESULTS. The median amount of subretinal TGF-beta2 was approximately two times lower in patients with postoperative PVR (1.9 ng/mL) than in the uncomplicated detachment group (3.3 ng/mL; P = 0.002). TGF-beta2 levels in the PVR-positive group were similar to control vitreous levels (1.8 ng/mL). Subretinal HGF concentrations were not significantly different between the two groups of patients (PVR positive: 8.8 ng/mL; PVR negative: 8.9 ng/mL), but were higher than control vitreous levels (4.6 ng/mL; P = 0.01). Stepwise multivariate logistic regression analysis revealed that of all factors under study, decreased TGF-beta2 content was the exclusive predictor of postoperative PVR (P = 0.01). CONCLUSIONS. High TGF-beta2 levels in subretinal fluid at the time of primary retinal detachment may protect a patient against subsequent development of PVR.

Aim: To investigate the role of two separate enzymatic pathways [soluble (sGC) vs. particulate (pGC) guanylyl cyclase] in the synthesis of cyclic GMP (cGMP) in cultured human retinal pigment epithelial (RPE) cells. Methods: cGMP accumulation was evaluated by quantitative analysis of cGMP immunoreactivity. RPE cells were also stained for inducible nitric oxide synthase (iNOS), ANP and β1- and α2-subunits of sGC. Results: We showed nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activity and iNOS immunoreactivity in RPE cells. Incubation of the cells in the presence of 1 mM IBMX to inhibit phosphodiesterase activity, and the simultaneous inhibition of NOS activity with L-NAME suggested the involvement of sGC in maintaining a low level of cGMP in the RPE cells. The involvement of sGC was further supported by detection of the β1- and α2-subunits of sGC. Incubation of the cells in the presence of atrial natriuretic peptide (ANP) to stimulate pGC strongly increased cGMP immunoreactivity. We also demonstrated the presence of ANP in all RPE cells. Conclusion: Cultured human RPE cells are capable of producing cGMP after stimulation of sGC or pGC. The presence of iNOS and ANP in all cells suggests two different autocrine pathways of stimulating cGMP production in these cells. The possible role of cGMP in the regulation iNOS gene expression and in the regulation of ANP is discussed.

Aim: To investigate which phosphodiesterase (PDE) is involved in regulating cyclic 3′5′ guanosine monophosphate breakdown in retinal pigment epithelium (RPE) cells. Methods: cGMP content in the cultured RPE cells (D407 cell line) was evaluated by immunocytochemistry in the presence of non-selective or isoform-selective PDE inhibitors in combination with the particulate guanylyl cyclase stimulator atrial natriuretic peptide (ANP) or the soluble guanylyl cyclase stimulator sodium nitroprusside (SNP). mRNA expression of PDE2, PDE5 and PDE9 was studied in cultured human RPE cells and rat RPE cell layers using non-radioactive in situ hybridisation. Results: In the absence of PDE inhibitors, cGMP levels in cultured RPE cells are very low. cGMP accumulation was readily detected in cultured human RPE cells after incubation with Bay60–7550 as a selective PDE2 inhibitor, sildenafil as a selective PDE5 inhibitor or Sch51866 as a selective PDE9 inhibitor. In the presence of PDE inhibition, cGMP content increased markedly after stimulation of the particulate guanylyl cyclase. mRNA of PDE2,PDE5 and PDE9 was detected in all cultured human RPE cells and also in rat RPE cell layers. Conclusions: PDE2, PDE5 and PDE9 have a role in cGMP metabolism in RPE cells.

Purpose To investigate whether the peeled internal limiting membrane (ILM) contains cellular retinal cell fragments, and to learn more about their possible origin. Design Experimental study. Methods ILM peeled from ten eyes during vitrectomy by infracyanine green (ICG) was studied immunohistochemically using the markers: GFAP, S-100, and vimentin. Five ILM specimens were from eyes with diabetic macular edema (DME), two from eyes with a macular hole, and three from eyes with persisting macular edema after retinal detachment surgery. Results In eight of the ten ILM specimens, we found GFAP-positive staining, indicating the presence of remnants of footplates from Muller cells or glial cells. Two ILM specimens were positive for S-100, indicating the presence of neural cells or ganglion cells. Conclusions ILM peeled from the retina during vitrectomy using ICG may contain remnants of Muller cell footplates, neural cells, and ganglion cells.