Rubeosis iridis nach Pars plana Vitrektomie

Laqua, H.

doi:10.1055/s-2008-1057605

Cited by 9 publications

(6 citation statements)

References 7 publications

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“…Another strong indication of changes in the perfusion of oxygen in the eye after vitrectomy towards the back of the eye is, in our opinion, clinical observation. It is known that there is a reduction in the risk of neovascularization in the retina (Blankenship & Machemer ), but there is an increased risk of the iris neovascularization after vitrectomy (Laqua ).…”

Section: Discussionmentioning

confidence: 99%

The effect of pars plana vitrectomy and nuclear cataract on oxygen saturation in retinal vessels, diabetic and non‐diabetic patients compared

Šín

Chrapek

Karhanová

et al. 2015

Acta Ophthalmologica

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ABSTRACT.Purpose: To determine the effect of pars plana vitrectomy (PPV) on oxygen saturation in retinal vessels in patients with diabetes and non-diabetes after a 1-year follow-up. Methods: This was a prospective consecutive interventional case series in 82 eyes in 82 patients. The sample consisted of 25 patients with non-proliferative diabetic retinopathy with macular oedema based on vitreoretinal traction or epiretinal membrane (ERM) and 57 non-diabetic patients with macular hole and ERM. Automatic retinal oximetry (Oxymap Inc.) was used on all patients 24 hr prior to PPV, and it was also used 7 and 52 weeks after PPV (classic 20G or sutureless 23G). We analysed the data according to subgroup diagnosis and lens status. Results: Arterial saturation increased significantly from 96.4 AE 2.9% at baseline to 96.6 AE 3.4% at week 7 and 97.3 AE 3.4% at week 52 (p < 0.0001; Friedman test). Vein saturation also increased significantly from 63.5 AE 7.9% at baseline to 66.1 AE 7.7% and 67.0 AE 7.2% at weeks 7 and 52 (p < 0.0001; Friedman test). The value of the arteriovenous (A-V) difference decreased significantly after vitrectomy from 32.8 AE 7.5% at baseline to 30.5 AE 7.5% and 30.3 AE 7.0% at weeks 7 and 52 (p < 0.0001; Friedman test). The subgroup analysis revealed that in patients with diabetes, there were no statistically significant changes in oxygen saturation in blood vessels or in the A-V difference after PPV. After vitrectomy, retinal vessel diameter reduced by about 3.5% in both groups of patients. Further, the analysis revealed that opacification of the lens leads to a decrease in oxygen saturation in contrast to a clear lens and pseudophakic IOLs. Conclusion: Oxygen saturation is higher in the retinal veins and arteries after PPV in patients with non-diabetes, and this lasts for at least 52 weeks. In contrast, in patients with diabetes, there is no increase in oxygen saturation in the retinal vessels after vitrectomy. After vitrectomy, retinal vessel diameter reduced in both groups of patients. Further, the nuclear cataract progression has substantial effect on oximetry results. Patients with nuclear cataract exhibited an increase in saturation in both arteries and veins, but the A-V difference remained the same.

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Section: Discussionmentioning

confidence: 99%

The effect of pars plana vitrectomy and nuclear cataract on oxygen saturation in retinal vessels, diabetic and non‐diabetic patients compared

Šín

Chrapek

Karhanová

et al. 2015

Acta Ophthalmologica

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“…The first unexpected clinical consequence of vitreous surgery was the increased risk of iris neovascularization following vitrectomy in diabetic retinopathy eyes, in particular if the lens had also been removed (36,37). In light of the previously described physiology this is easy to understand.…”

Section: Iris Neovascularizationmentioning

confidence: 93%

Physiology of vitreous surgery

Stefánsson

2008

Graefes Arch Clin Exp Ophthalmol

249

195

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Vitreous surgery has various physiological and clinical consequences, both beneficial and harmful. Vitrectomy reduces the risk of retinal neovascularization, while increasing the risk of iris neovascularization, reduces macular edema and stimulates cataract formation. These clinical consequences may be understood with the help of classical laws of physics and physiology. The laws of Fick, Stokes-Einstein and Hagen-Poiseuille state that molecular transport by diffusion or convection is inversely related to the viscosity of the medium. When the vitreous gel is replaced with less viscous saline, the transport of all molecules, including oxygen and cytokines, is facilitated. Oxygen transport to ischemic retinal areas is improved, as is clearance of VEGF and other cytokines from these areas, thus reducing edema and neovascularization. At the same time, oxygen is transported faster down a concentration gradient from the anterior to the posterior segment, while VEGF moves in the opposite direction, making the anterior segment less oxygenated and with more VEGF, stimulating iris neovascularization. Silicone oil is the exception that proves the rule: it is more viscous than vitreous humour, re-establishes the transport barrier to oxygen and VEGF, and reduces the risk for iris neovascularization in the vitrectomized-lentectomized eye. Modern vitreous surgery involves a variety of treatment options in addition to vitrectomy itself, such as photocoagulation, anti-VEGF drugs, intravitreal steroids and release of vitreoretinal traction. A full understanding of these treatment modalities allows sensible combination of treatment options. Retinal photocoagulation has repeatedly been shown to improve retinal oxygenation, as does vitrectomy. Oxygen naturally reduces VEGF production and improves retinal hemodynamics. The VEGF-lowering effect of photocoagulation and vitrectomy can be augmented with anti-VEGF drugs and the permeability effect of VEGF reduced with corticosteroids. Starling's law explains vasogenic edema, which is controlled by osmotic and hydrostatic gradients between vessel and tissue. It explains the effect of VEGF-induced vascular permeability changes on plasma protein leakage and the osmotic gradient between vessel and tissue. At the same time, it takes into account hemodynamic changes that affect the hydrostatic gradient. This includes the influence of arterial blood pressure, and the effect oxygen (laser treatment) has in constricting retinal arterioles, increasing their resistance, and thus reducing the hydrostatic pressure in the microcirculation. Reduced capillary hydrostatic pressure and increased osmotic gradient reduce water fluxes from vessel to tissue and reduce edema. Finally, Newton's third law explains that vitreoretinal traction decreases hydrostatic tissue pressure in the retina, increases the pressure gradient between vessel and tissue, and stimulates water fluxes from vessel into tissue, leading to edema.

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“…The procedure lowers the risk of neovascularization of the retina and choroidea (Blankenship & Machemer 1985; Ikeda et al. 2000), but increases the risk of anterior chamber neovascularization (Laqua 1980), cataract formation (Holekamp et al. 2005) as well as of primary open‐angle glaucoma (Chang 2006).…”

Section: Introductionmentioning

confidence: 99%

“…For example, oxygen transport and local availability of growth factor may both be altered (Stefa´nsson 2009). The procedure lowers the risk of neovascularization of the retina and choroidea (Blankenship & Machemer 1985;Ikeda et al 2000), but increases the risk of anterior chamber neovascularization (Laqua 1980), cataract formation (Holekamp et al 2005) as well as of primary open-angle glaucoma (Chang 2006). In 2006, Hardarson et al (2006 introduced noninvasive measurement of oxygen saturation in retinal blood vessels by automatic retinal oximetry (Oxymap Inc, Reykjavik, Iceland).…”

Section: Introductionmentioning

confidence: 99%

The effect of pars plan vitrectomy on oxygen saturation in retinal vessels – a pilot study

Šín

Šínová

Chrapek

et al. 2013

Acta Ophthalmologica

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ABSTRACT.Purpose: To determine the effect of pars plana vitrectomy (PPV) on oxygen saturation in retinal vessels. Methods: We performed a prospective consecutive interventional case series of 20 eyes of 20 patients with macular hole or epiretinal membrane. We performed automatic retinal oximetry (Oxymap Inc., Reykjavik, Iceland) in each patient 24 hr prior to and 45 days (range 42-49) after PPV (classic 20G or sutureless 23G). We analysed oxygen saturations in retinal arteries and veins. Vessel segments of first or second degree were selected. The same segment was analysed before and after PPV. Oximetry data were compared by paired two-tailed t-test. Results: Pars plana vitrectomy did not alter arterial haemoglobin saturation with oxygen (98 ± 2% prior to the surgery and 98 ± 3% after the procedure, p = 0.549). The mean venous haemoglobin saturation with oxygen increased after vitrectomy from 63 ± 10% to 66 ± 8% (p = 0.012). Conclusions: Oxygen saturation is higher in retinal veins after pars plana vitrectomy. Further studies are needed to unveil the mechanism of how vitrectomy affects oxygen metabolism in the retina.

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Rubeosis iridis nach Pars plana Vitrektomie

Cited by 9 publications

References 7 publications

The effect of pars plana vitrectomy and nuclear cataract on oxygen saturation in retinal vessels, diabetic and non‐diabetic patients compared

The effect of pars plana vitrectomy and nuclear cataract on oxygen saturation in retinal vessels, diabetic and non‐diabetic patients compared

Physiology of vitreous surgery

The effect of pars plan vitrectomy on oxygen saturation in retinal vessels – a pilot study

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