The impact of ocular blood flow in glaucoma.

Optical Coherence Tomography Angiography of Optic Disc Perfusion in Glaucoma

Purpose To compare optic disc perfusion between normal subjects and subjects with glaucoma using optical coherence tomography (OCT) angiography and to detect optic disc perfusion changes in glaucoma. Design Observational, cross-sectional study. Participants Twenty-four normal subjects and 11 patients with glaucoma were included. Methods One eye of each subject was scanned by a high-speed 1050-nm–wavelength swept-source OCT instrument. The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to compute 3-dimensional optic disc angiography. A disc flow index was computed from 4 registered scans. Confocal scanning laser ophthalmoscopy (cSLO) was used to measure disc rim area, and stereo photography was used to evaluate cup/disc (C/D) ratios. Wide-field OCT scans over the discs were used to measure retinal nerve fiber layer (NFL) thickness. Main Outcome Measures Variability was assessed by coefficient of variation (CV). Diagnostic accuracy was assessed by sensitivity and specificity. Comparisons between glaucoma and normal groups were analyzed by Wilcoxon rank-sum test. Correlations among disc flow index, structural assessments, and visual field (VF) parameters were assessed by linear regression. Results In normal discs, a dense microvascular network was visible on OCT angiography. This network was visibly attenuated in subjects with glaucoma. The intra-visit repeatability, inter-visit reproducibility, and normal population variability of the optic disc flow index were 1.2%, 4.2%, and 5.0% CV, respectively. The disc flow index was reduced by 25% in the glaucoma group ( P = 0.003). Sensitivity and specificity were both 100% using an optimized cutoff. The flow index was highly correlated with VF pattern standard deviation ( R 2  = 0.752, P = 0.001). These correlations were significant even after accounting for age, C/D area ratio, NFL, and rim area. Conclusions Optical coherence tomography angiography, generated by the new SSADA, repeatably measures optic disc perfusion and may be useful in the evaluation of glaucoma and glaucoma progression.

Importance Vascular factors may have important roles in the pathophysiology of glaucoma. A practical method for the clinical evaluation of ocular perfusion is needed to improve glaucoma management. Objective To detect peripapillary retinal perfusion in glaucomatous eyes compared with normal eyes using optical coherence tomography (OCT) angiography. Design, Setting, and Participants Prospective observational study performed from July 24, 2013, to April 17, 2014. Participants were recruited and tested at Casey Eye Institute, Oregon Health & Science University. In total, 12 glaucomatous eyes and 12 age-matched normal eyes were analyzed. The optic disc region was imaged twice using a 3 × 3-mm scan by a 70-kHz, 840-nm-wavelength spectral OCT system. The split-spectrum amplitude-decorrelation angiography algorithm was used. Peripapillary flow index was calculated as the mean decorrelation value in the peripapillary region, defined as a 700-µm-wide elliptical annulus around the disc. Peripapillary vessel density was the percentage area occupied by vessels. The data statistical analysis was performed from October 30, 2013, to May 30, 2014. Main Outcomes and Measures Variability was assessed by the coefficient of variation. The Mann-Whitney test was used to compare the 2 groups of eyes. Correlations between vascular and visual field variables were assessed by linear regression analysis. Results In 12 normal eyes, a dense microvascular network around the disc was visible on OCT angiography. In 12 glaucomatous eyes, this network was visibly attenuated globally and focally. In normal eyes, between-visit reproducibilities of peripapillary flow index and peripapillary vessel density were 4.3% and 2.7% of the coefficient of variation, respectively, while the population variabilities of peripapillary flow index and peripapillary vessel density were 8.2% and 3.0% of the coefficient of variation, respectively. Peripapillary flow index and peripapillary vessel density in glaucomatous eyes were lower than those in normal eyes ( P r  = −0.808) and peripapillary vessel density (Pearson r  = −0.835) were highly correlated with visual field pattern standard deviation in glaucomatous eyes ( P  = .001 for both). The areas under the receiver operating characteristic curve for normal vs glaucomatous eyes were 0.892 for peripapillary flow index and 0.938 for peripapillary vessel density. Conclusions and Relevance Using OCT angiography, reduced peripapillary retinal perfusion in glaucomatous eyes can be visualized as focal defects and quantified as peripapillary flow index and peripapillary vessel density, with high repeatability and reproducibility. Quantitative OCT angiography may have value in future studies to determine its potential usefulness in glaucoma evaluation.

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Optical coherence tomography angiography of the peripapillary retina in glaucoma

Optic nerve head (ONH) blood flow may be associated with glaucoma development. A reliable method to quantify ONH blood flow could provide insight into the vascular component of glaucoma pathophysiology. Using ultrahigh-speed optical coherence tomography (OCT), we developed a new 3D angiography algorithm called split-spectrum amplitude-decorrelation angiography (SSADA) for imaging ONH microcirculation. In this study, a method to quantify SSADA results was developed and used to detect ONH perfusion changes in early glaucoma. En face maximum projection was used to obtain 2D disc angiograms, from which the average decorrelation values (flow index) and the percentage area occupied by vessels (vessel density) were computed from the optic disc and a selected region within it. Preperimetric glaucoma patients had significant reductions of ONH perfusion compared to normals. This pilot study indicates OCT angiography can detect the abnormalities of ONH perfusion and has the potential to reveal the ONH blood flow mechanism related to glaucoma.

Quantitative OCT angiography of optic nerve head blood flow

Optic disc blood flow velocity was measured in healthy patients, those with primary open angle glaucoma (POAG), and patients with normal pressure glaucoma (NPG). The velocity of the red blood cells (RBCs) in the capillaries of the optic nerve head (ONH) has been measured with a laser Doppler velocimeter (LDV), and blood viscosity has been evaluated notably by determining the aggregability of the RBCs with an erythroaggregameter. Our results in POAG patients and NPG patients showed that their optic nerve blood flow velocity was reduced and that the aggregability of the RBCs was increased. The hyperaggregability of the erythrocytes is responsible for the increase of the local viscosity in the papillary capillary network. These haemodynamic modifications observed in patients with glaucoma support the hypothesis of a vasogenic mechanism that could impair the optic nerve in glaucoma patients.

https://bjo.bmj.com/content/bjophthalmol/78/6/449.full.pdf

Optic nerve head blood flow using a laser Doppler velocimeter and haemorheology in primary open angle glaucoma and normal pressure glaucoma.

PURPOSE The aim of this retropective study is to evaluate and to compare in glaucoma patients, the mid-term results of the non penetrating deep-sclerectomy (NPDS) with collagen implant or with per operative application of 5 fluorouracile (5 FU). MATERIAL AND METHODS The aim of the NPDS, a new filtering surgical procedure, is to remove under a scleral flap the Schlemm's canal and the juxtacanalicular trabecular meshwork responsible for the outflow resistance in order to obtain a sub-conjunctival filtration of the aqueous humor with no opening of the anterior chamber. Forty-two open angle glaucoma patients with uncontrolled intra-ocular pressure and with no risk factor of bleb fibrosis, underwent a NPDS. In 27 eyes (group 1) a sponge soaked with 5 FU (50 mg/ml) was applied for 5 minutes in the scleral bed, and in 15 eyes (group-2) a collagen implant (Staar*) was sutured in the scleral bed. A complete ophthalmologic examination was performed on days 1, 8, months 1,2,3 and each 3 months until the end of the follow-up. In case of increased IOP, goniopuncture with the Nd: YAG laser was performed at any time of the post operative period. RESULTS The mean intra-ocular pressure (IOP) significantly decreased from 23.5 +/- 5.1 mmHg to 15.5 +/- 2.9 at 11.1 +/- 5.6 months follow-up (group 1, p < 10(-3)) and from 22.6 +/- 6.9 Hg to 16.2 +/- 3.9 mmHg at 8.8, 3.6 months follow-up (group 2, p < 10(-3)) with a significant decrease in the medical treatment (p < 10(-3)). The Kaplan Meier probability of success (IOP < or = 20 mmHg without treatment and with no visual field deterioration) at 6 and 12 months was similar in both groups: 57.3% (group 1) and 66.0% (group 2) with a mean decrease in IOP of 30%. Goniopuncture had to be performed in more than one third of case in each group and was effective to control the IOP in half of the cases. No complication related to hypotony or inflammation occured in the post operative period. CONCLUSION NPDS is an interesting alternative to the classical trabeculectomy since the post operative complications are markedly reduced. However, the mid-term control in IOP appears to be slightly lower. The use of a collagen device does not lead to better control in IOP as compared to the use of a sponge of 5 FU.

Deep nonpenetrating sclerectomy and open angle glaucoma. Intermediate results from the first operated patients

But Evaluer l'efficacite et les complications du traitement des glaucomes refractaires par cyclo-photo-coagulation transsclerale au laser Diode. Materiel et methode Nous avons utilise le laser semi-conducteur Diode (Iris Medical Oculight SLX) pour traiter 50 yeux de 47 patients presentant un glaucome refractaire au traitement medical et ou chirurgical. Chaque patient avait le traitement hypotonisant maximal tolerable et 40 d'entre eux (82 %) etaient sous Diamox. L'energie du laser diode a ete transmise au corps ciliaire en transscleral par l'intermediaire d'une fibre optique en quartz posee sur la sclere (13 a 20 impacts repartis sur 270° du corps ciliaire), 3,5 Joules par impact (1,75 Watts x 2 s). Le suivi moyen a ete de 19,4 ± 9,1 mois (de 12 a 29 mois) Resultats Un abaissement significatif de la tension oculaire a ete obtenu apres une ou plusieurs cyclophotocoagulation par le laser diode (32,4 ± 9,1 mmHg en pre-operatoire contre 19,7 ± 8,1 mmHg a la derniere visite de controle (p < 10 -3 ). Soixante-six pour-cent des patients avaient une tension oculaire inferieure ou egale a 20 mmHg a la derniere consultation. Le Diamox a pu etre arrete chez 13 patients. Les douleurs oculaires ont ete supprimees chez 6 patients sur 8. Une baisse visuelle a ete notee dans 34 % des cas (17 yeux) liee a a progression d'opaciees cristalliniennes dans 5 cas, a une hypertonie oculaire residuelle dans 4 cas, a l'evolution de la neuropathie glaucomateuse malgre une tension oculaire inferieure ou egale a 20 mmHg dans 3 cas, a une decompensation corneenne dans 3 cas. Cinq yeux (10 %) ont presente une uveite chronique. Un oeil atteint de glaucome neovasculaire est devenu hypotone au bout d'un mois. Aucune alteration conjonctivale, sclerale ou cristallinienne n'a ete relevee. Conclusion La cyclophotocoagulation transsclerale au laser semi-conducteur Diode est efficace pour abaisser la tension des glaucomes refractaires. Les complications sont rares et moderees.

[Treatment of refractory glaucomas by transscleral cyclophotocoagulation using semiconductor diode laser. Analysis of 50 patients followed-up over 19 months].

But La destruction du corps ciliaire s'adresse uniquement aux glaucomes refractaires, pour reduire la pression intraoculaire ou pour supprimer les douleurs. Nous avons evalue a trois mois l'efficacite d'une cyclophotocoagulation transsclerale realisee par un laser sermi-conducteur a diode (Oculight SLX Iris Medical). Materiel et methodes L'energie du laser, de longueur d'onde de 810 nm, est transmise au corps ciliaire par l'intermediaire d'une fibre optique en quartz. Grâce a la forme particuliere de l'extremite de la sonde, on est assure d'etre en regard des proces ciliaires lors du traitement, ce qui reduit l'incidence des complications. Trente-huit patients presentant un glaucome refractaire ont ete traites. Resultats Trois mois apres le laser, 70 % de succes pressionnels (PIO inferieure ou egale a 20 mmHg) ont ete observes, et 75 % des yeux douloureux traites ne l'etaient plus. Les effets secondaires (hypertonie, reaction inflammmatoire) ont ete transitoires et moderes. Nous n'avons rapporte aucune complication majeure (aucune perforation sclerale, pas d'atteinte cristallinienne, pas d'hypotonie). Conclusion La cyclophotocoagulation au laser a diode est une methode efficace, du moins a court terme, pour reduire la pression intraoculaire des glaucomes refractaires et pour supprimer les douleurs. Les effets secondaires sont moindres compares aux autres methodes de cyclo-affaiblissement. Un suivi a plus long terme est necessaire pour evaluer la stabilite de la reduction pressionnelle, ainsi que l'incidence eventuelle d'hypotonie, toujours a redouter avec les methodes de cyclo-affaiblissement.

Treatment of refractory glaucoma by diode semiconductor laser cyclophotocoagulation

Introduction : Evaluer l'efficacite et les complications de la cyclophotocoagulation transsclerale (CPTS) au laser diode dans les glaucomes refractaires du sujet jeune. Materiel et methode : Cette etude retrospective porte sur 28 yeux de 28 patients âges de 5 mois a 26 ans, qui presentaient une hypertonie oculaire refractaire au traitement medical et chirurgical (groupe 1 : 20 glaucomes congenitaux primitifs, groupe 2 : 8 glaucomes secondaires) et qui ont ete traites par CPTS au laser diode (Oculight, SLX, Iris medical). Le succes tensionnel de la CPTS a ete defini comme une pression intra-oculaire finale (PIO) comprise entre 6 et 20 mmHg, sans majoration du traitement medical initial, apres une ou plusieurs seances de CPTS. Resultats : La PIO initiale moyenne etait de 29,4 ± 7,8 mmHg (de 25 a 60 mmHg) tandis que la PIO moyenne finale etait de 25,8 ± 10,0 mmHg, pour un suivi moyen de 10,3 ± 6,9 mois (de 2 a 26 mois). Le succes tensionnel, evalue selon la methode de Kaplan Meier, est passe de 55,4 % a 6 mois a 27,7 % a 12 mois, un tiers des patients ayant ete retraites Les taux de succes se sont averes etre equivalents dans les groupes 1 et 2, et correspondaient a une baisse tensionnelle moyenne de 38,9 ± 15,9 %. Les complications marquantes de la CPTS au laser diode ont ete des hypertonies oculaires secondaires refractaires au traitement medical dans 21,4% des cas, des reactions inflammatoires severes dans 25 % des cas, des baisses visuelles dans 14,3 % des cas tandis qu'un oeil a evolue vers la phtyse apres deux retraitements. Conclusion : La CPTS au laser diode s'avere decevante a moyen terme dans le controle tensionnel des glaucomes refractaires du sujet jeune, tandis qu'elle expose a des complications de traitement difficile. Pour ces raisons, la CPTS au laser diode doit vraiment rester l'arme de dernier recours chez ces jeunes patients.

S Quesnot

Papers

Optic nerve head blood flow using a laser Doppler velocimeter and haemorheology in primary open angle glaucoma and normal pressure glaucoma.

Deep nonpenetrating sclerectomy and open angle glaucoma. Intermediate results from the first operated patients

[Treatment of refractory glaucomas by transscleral cyclophotocoagulation using semiconductor diode laser. Analysis of 50 patients followed-up over 19 months].

Treatment of refractory glaucoma by diode semiconductor laser cyclophotocoagulation

La cyclophotocoagulation transsclérale au laser diode dans le traitement des glaucomes réfractaires du sujet jeune