Formation of retinochoroidal collaterals in central retinal vein occlusion

The Caliber of Optociliary Shunt Vessels Is Associated with Macular Blood Flow and Visual Acuity in Central Retinal Vein Occlusion

Purpose

To define the role of optociliary shunt vessels (OSVs) in eyes with central retinal vein occlusion (CRVO) using OCT angiography (OCTA) with macular parameters.

Design

Retrospective, observational, consecutive case series.

Participants

Forty-one eyes in 38 consecutive patients with CRVO were analyzed in this study.

Methods

Optic disc and macula were imaged by swept-source OCTA (3 × 3 mm) as well as by high-quality fundus photography.

Main Outcome Measures

We compared macular vessel density (VD) and visual acuity between eyes in which OSVs developed and those in which they did not. Furthermore, we measured the diameter of the OSVs and analyzed the correlation with macular VD and visual acuity.

Results

Optociliary shunt vessels were found in 25 eyes (61%). Central retinal vein occlusion with OSVs did not show any statistical difference compared with CRVO without OSVs in either macular VD of the total retina (0.31 ± 0.07 and 0.26 ± 0.09, respectively; P = 0.0937) or final best-corrected visual acuity (BCVA) (0.30 ± 0.43 logarithm of the minimum angle of resolution [logMAR] and 0.59 ± 0.54 logMAR, respectively; P = 0.0705). The mean OSV diameter was 71 ± 30 μm in CRVO with OSV. The diameter of the OSVs was correlated positively with superficial VD (r = 0.443; P = 0.027), deep VD (r = 0.494; P = 0.012), and total VD (r = 0.491; P = 0.013). Furthermore, the OSV diameter was also negatively correlated with BCVA (logMAR) at the final visit (r = –0.531; P = 0.006).

Conclusions

The results demonstrated that the diameter of the OSVs was associated with macular VD and visual acuity in patients with CRVO. The development of large OSVs on the optic disc may be a good indicator of the maintenance of blood flow in the macula.

Pre- and juxtapapillary arterial loops in eyes with tilted disc syndrome and inferior staphyloma

Purpose

To report and discuss the association between pre- or juxtapapillary arterial loops and tilted disc syndrome (TDS).

Observations

Three patients, aged 43–59 years, with both conditions were examined in a tertiary referral center, and underwent fluorescein angiography, optical coherence tomography (OCT) and/or OCT-angiography. They all presented with a typical inferior staphyloma associated with TDS and anomalies of insertion of retinal vessels. The vascular malformation consisted in one acquired arterial loop or cilioretinal collateral circulation occurring after central artery occlusion, and two more complex pre- and juxtapapillary arterial loops. In all cases, the vascular loops extended inferiorly, in the area of the staphyloma.

Conclusion and importance

We hypothesized that the local anatomical changes in the peripapillary area, observed in eyes with TDS and inferior staphyloma, could have promoted the occurrence and/or extent of the arterial loops.

Current use of the automatic retinal oximetry. Review

PURPOSE

To inform about possible use of the automatic retinal oximetry for the retinal oxygen saturation measurement in the eye and systemic diseases.

METHODS

We performed a literature review dealing with issues of retinal oxygen saturation monitoring by dual non-invasive retinal oximetry Oxymap T1 (Oxymap ehf. Reykjavík, Iceland).

RESULTS

We have found two main strains writing our paper on retinal oxygen saturation eye diseases. The first section concerns diseases created by having hypoxia as its main pathological factor  - for example diabetes mellitus and retinal vein occlusion. The second group deals with atrophy as the main pathological mechanism which is typical for decreasing retinal oxygen consumption - for example glaucoma or retinitis pigmentosa (the second one named is not included in our work). Oximetry in systemic diseases creates a relatively new chapter of this branch with a very big potential of interdisciplinary cooperation for the future. It is possible the cooperation will not only include diabetologists but also neurologists (for example, in diseases like sclerosis multiplex or Devics, Alzheimers and Parkinsons disease) and haematologists (retinal oxygen saturation changes in patients with different rheological attributes of blood).

CONCLUSION

Retinal oxygen saturation measuring by automatic retinal oximetry is a relatively new method with scientifically confirmed high reproducibility of results. Currently it is the only experimental method with vast potentials not only in the realm of the possibility of observing eye diseases (diabetic retinopathy, retinal vein occlusion or glaucoma) but also in developing interdisciplinary cooperation with diabetologists, neurologists and haematologists.

Cilioretinal Arteries and Cilioretinal Veins in Eyes with Pathologic Myopia

We investigated the clinical characteristics of cilioretinal arteries (CAs) and cilioretinal veins (CVs) in eyes with pathologic myopia. Ninety-five eyes with pathologic myopia and CAs were studied. The retrobulbar vessels from which the CAs originated were identified by indocyanine green angiography (ICGA). The results showed that 114 CAs were identified in the 95 eyes. ICGA showed that 60% of the CAs branched directly off the short posterior ciliary arteries (SPCAs) and 40% originated from the Zinn-Haller arterial circle (ZHAC). The SPCA-derived CAs tended to be located superiorly and served a large retinal area whereas the ZHAC-associated CAs tended to be located temporally and served mainly the macular area. In 15% of the 95 eyes, the CVs were observed to run parallel to the CAs. The CVs exited the eye at the same point where the CAs entered the eye. This study showed that CAs in eyes with pathologic myopia can be divided into those that are SPCA-derived and tend to emerge in the superior optic disc sector, and those that are ZHAC-associated and usually emerge temporally. An elongating peripapillary scleral flange in eyes with progressive axial myopia may lead to a change of chorioretinal vascular system.

Retinal oximetry and systemic arterial oxygen levels

PURPOSE

Continuous peripheral pulse oximetry for monitoring adequacy of oxygenation is probably the most important technological advance for patients' monitoring and safety in the last decades. Pulse oximetry has the disadvantage of measuring the peripheral circulation, and the only mean to measure oxygen content of the central circulation is by invasive technology. Determination of blood oxyhaemoglobin saturation in the retinal vessels of the eye can be achieved noninvasively through spectrophotometric retinal oximetry which provides access to the central nervous system circulation. The aim of the thesis was to determine whether retinal oximetry technique can be applied for estimation of the central nervous system circulation which until now has only been possible invasively. This was achieved by measuring oxyhaemoglobin saturation in three adult subject study groups: in people with central retinal vein occlusion (CRVO) to observe local tissue hypoxia, in patients with severe chronic obstructive pulmonary disease (COPD) on long-term oxygen therapy to observe systemic hypoxaemia and in healthy subjects during hyperoxic breathing to observe systemic hyperoxemia. In addition, the fourth study that is mentioned was performed to test whether retinal oximetry is feasible for neonates.

METHODS

Retinal oximetry in central retinal vein occlusion: Sixteen subjects with central retinal vein occlusion participated in the study. The oxyhaemoglobin saturation of the central retinal vein occlusion affected eye was compared with the fellow unaffected eye. Retinal oximetry in healthy people under hyperoxia: Thirty healthy subjects participated in the study, and the oxyhaemoglobin saturation of retinal arterioles and venules was compared between normoxic and hyperoxic breathing. Retinal oximetry in severe chronic obstructive pulmonary disease: Eleven patients with severe chronic obstructive pulmonary disease participated in the study. Retinal oximetry measurements were made with and without their daily supplemental oxygen therapy. Retinal arteriolar oxyhaemoglobin saturation when inspiring ambient air was compared with blood samples from the radial artery and finger pulse oximetry and healthy controls. The healthy control group was assembled from our database for comparison of oxyhaemoglobin saturation of retinal arterioles and venules during the ambient air breathing. The retinal oximeter is based on a conventional fundus camera and a specialized software. A beam splitter coupled with two high-resolution digital cameras allows for simultaneous acquisition of retinal images at separative wavelengths for calculation of oxyhaemoglobin saturation. In addition, retinal images of 28 full-term healthy neonates were obtained with scanning laser ophthalmoscope combined with modified Oxymap analysis software for calculation of the optical density ratio and vessel diameter RESULTS: Retinal oximetry in central retinal vein occlusion: Mean retinal venous oxyhaemoglobin saturation was 31 ± 12% in CRVO eyes and 52 ± 11% in unaffected fellow eyes (mean ± SD, n = 14, p < 0.0001). The arteriovenous oxygen difference (AV-difference) was 63 ± 11% in CRVO eyes and 43 ± 7% in fellow eyes (p < 0.0001). The variability of retinal venous oxyhaemoglobin saturation was considerable within and between eyes affected by CRVO. There was no difference in oxyhaemoglobin saturation of retinal arterioles between the CRVO eyes and the unaffected eyes (p = 0.49). Retinal oximetry in healthy people under hyperoxia: During hyperoxic breathing, the oxyhaemoglobin saturation in retinal arterioles increased to 94.5 ± 3.8% as compared with 92.0 ± 3.7% at baseline (n = 30, p < 0.0001). In venules, the mean oxyhaemoglobin saturation increased to 76.2 ± 8.0% from 51.3 ± 5.6% (p < 0.0001) at baseline. The AV-difference was markedly lower during hyperoxic breathing as compared with the normoxic breathing (18.3 ± 9.0% versus 40.7 ± 5.7%, p < 0.0001). Retinal oximetry in severe chronic obstructive pulmonary disease: During ambient air breathing, chronic obstructive pulmonary disease subjects had significantly lower oxyhaemoglobin saturation than healthy controls in both retinal arterioles (87.2 ± 4.9% versus 93.4 ± 4.3%, p = 0.02, n = 11) and venules (45.0 ± 10.3% versus 55.2 ± 5.5%, p = 0.01) but the AV-difference was not markedly different (p = 0.17). Administration of their prescribed oxygen therapy significantly increased the oxyhaemoglobin saturation in retinal arterioles (87.2 ± 4.9% to 89.5 ± 6.0%, p = 0.02) but not in venules (45.0 ± 10.3% to 46.7 ± 12.8%, p = 0.3). Retinal oximetry values were slightly lower than finger pulse oximetry (mean percentage points difference = -3.1 ± 5.5) and radial artery blood values (-5.0 ± 5.4). Retinal oximetry study in neonates: The modified version of the retinal oximetry instrument estimated the optical density ratio in retinal arterioles to be 0.256 ± 0.041 that was significantly different from the 0.421 ± 0.089 in venules (n = 28, p < 0.001, paired t-test). The vascular diameter of retinal arterioles was markedly narrower than of venules (14.1 ± 2.7 and 19.7 ± 3.7 pixels, p < 0.001).

CONCLUSION

The results of this thesis indicate that spectrophotometric retinal oximetry is sensitive to both local and systemic changes in oxyhaemoglobin saturation. Retinal oxyhaemoglobin saturation values are slightly lower than radial artery blood sample and finger pulse oximetry values. The discrepancies between the different modalities are expected to derive from countercurrent exchange between central retinal artery and vein within the optic nerve but calibration issues cannot be excluded as contributing to this difference. Despite these differences, the findings indicate the potential of retinal oximetry for noninvasive real-time measurements of oxyhaemoglobin saturation in central nervous system vessels. Following calibration upgrade and technological improvement, verification retinal oximetry may potentially be applied to critically ill and anaesthesia care patients. The study on combined scanning laser ophthalmoscope and retinal oximetry supports the feasibility of the technique for oximetry analysis in newly born babies.

Retinal oximetry in patients with ischaemic retinal diseases

The retinal oximeter is a new tool for non-invasive measurement of retinal oxygen saturation in humans. Several studies have investigated the associations between retinal oxygen saturation and retinal diseases. In the present systematic review, we examine whether there are associations between retinal oxygen saturation and retinal ischaemic diseases. We used PubMed and Embase to search for retinal oxygen saturation and retinal ischaemic diseases. Three separate searches identified a total of 79 publications. After two levels of manual screening, 10 studies were included: six about diabetic retinopathy (DR) and four about retinal vein occlusion. No studies about retinal artery occlusion were included. In diabetes, all studies found that increases in retinal venous oxygen saturation (rvSatO₂ ) were associated with present as well as increasing levels of DR. Four of six studies also found increased retinal arterial oxygen saturation (raSatO₂ ) in patients with DR. In patients with central retinal vein occlusion (CRVO), all studies found that rvSatO₂ was reduced, but raSatO₂ remained unchanged. Branch retinal vein occlusion was not associated with changes in retinal oxygen saturation, but this was based on a single study. In conclusion, DR is associated with increased rvSatO₂ and might also be related to increased raSatO₂ . Central retinal vein occlusion (CRVO) is correlated with increased rvSatO₂ but unrelated to raSatO₂ . Prospective studies are needed to expand these findings. These would tell whether retinal oximetry could be a potential tool for screening or a biomarker of treatment outcome in patients with ischaemic retinal diseases.

Fundus changes in central retinal vein occlusion

PURPOSE

To investigate systematically the retinal and optic disk changes in central retinal vein occlusion (CRVO) and their natural history.

METHODS

This study comprised 562 consecutive patients with CRVO (492 nonischemic [NI-CRVO] and 89 ischemic CRVO [I-CRVO] eyes) seen within 3 months of onset. Ophthalmic evaluation at initial and follow-up visits included recording visual acuity, visual fields, and detailed anterior segment and fundus examinations and fluorescein fundus angiography.

RESULTS

Retinal and subinternal limiting membrane hemorrhages and optic disk edema in I-CRVO were initially more marked (P < 0.0001) and took longer to resolve (P < 0.015) than that in NI-CRVO. Initially, macular edema was more marked in I-CRVO than that in NI-CRVO (P < 0.0001) but did not significantly differ in resolution time (P = 0.238). Macular retinal epithelial pigment degeneration, serous macular detachment, and retinal perivenous sheathing developed at a higher rate in I-CRVO than that in NI-CRVO (P < 0.0001). Ischemic CRVO had more retinal venous engorgement than NI-CRVO (P = 0.003). Fluorescein fundus angiography showed significantly more fluorescein leakage, retinal capillary dilatation, capillary obliteration, and broken capillary foveal arcade (P < 0.0001) in I-CRVO than NI-CRVO. Resolution time of CRVO was longer for I-CRVO than NI-CRVO (P < 0.0001).

CONCLUSION

Characteristics and natural history of fundus findings in the two types of CRVO are different.

Venous oxygen saturation is reduced and variable in central retinal vein occlusion

PURPOSE

To estimate the presence and variability of retinal hypoxia in patients with central retinal vein occlusion (CRVO).

METHOD

Hemoglobin oxygen saturation was measured in retinal vessels of both eyes in 14 patients with unilateral CRVO. The noninvasive spectrophotometric retinal oximeter is based on a fundus camera and simultaneously captures two images at 570 nm and 600 nm wavelengths. Five of the patients were followed with repeated retinal oximetry images over time.

RESULTS

The mean oxygen saturation in retinal venules was 31 % ±12 % in CRVO eyes and 52 % ±11 % in unaffected fellow eyes (mean ±SD, n = 14, p < 0.0001). The arteriovenous difference was 63 % ±11 % in eyes with CRVO and 43 % ±7 % in fellow eyes (p < 0.0001). The variability of retinal venous oxygen saturation was substantial within and between eyes affected by CRVO. Venular oxygen saturation improved with treatment and over time in all five patients that were followed.

CONCLUSION

CRVO eyes are hypoxic compared to fellow eyes and arteriovenous difference in hemoglobin oxygen saturation is increased. This is consistent with tissue hypoxia resulting from reduced blood flow. Further studies are needed to understand the correlation between hypoxia, severity of disease and prognosis.

Score Study Report 12: Development of venous collaterals in the Score Study

PURPOSE

To investigate the prevalence of venous collaterals after branch and central retinal vein occlusion, assess the association of venous collaterals with other clinical features (including visual acuity), and determine if treatment with intravitreal corticosteroids influences the development of new venous collaterals.

METHODS

Review of data from two multicenter randomized clinical trials in the Standard of Care versus COrticosteroid for REtinal Vein Occlusion (SCORE) Study.

RESULTS

Statistically significant associations of venous collaterals and visual acuity at baseline or at follow-up were not found. Treatment with intravitreal triamcinolone acetonide did not appear to influence the development of venous collaterals.

CONCLUSION

In contrast to some previous reports, development of venous collaterals did not demonstrate an independent association with visual acuity in eyes with branch retinal vein occlusion or central retinal vein occlusion in the SCORE Study. Intravitreal steroid effects do not appear to influence the development of venous collaterals.

Retinal oximetry

ABSTRACT.:

PURPOSE

Malfunction of retinal blood flow or oxygenation is believed to be involved in various diseases. Among them are retinal vessel occlusions, diabetic retinopathy and glaucoma. Reliable, non-invasive technology for retinal oxygen measurements has been scarce and most of the knowledge on retinal oxygenation comes from animal studies. This thesis describes human retinal oximetry, performed with novel retinal oximetry technology. The thesis describes studies on retinal vessel oxygen saturation in (1) light and dark in healthy volunteers, (2) central retinal vein occlusion, (3) branch retinal vein occlusion, (4) central retinal artery occlusion, (5) diabetic retinopathy, (6) patients undergoing glaucoma surgery and (7) patients taking glaucoma medication.

METHODS

The retinal oximeter (Oxymap ehf., Reykjavik, Iceland) is based on a fundus camera. An attached image splitter allows the simultaneous capture of four images of the same area of the fundus. Two images are used for further analysis, one acquired with 586 nm light and one with 605 nm light. Light absorbance of retinal vessels is sensitive to oxygen saturation at 605 nm but not at 586 nm. Measurement of reflected light at these wavelengths allows estimation of oxygen saturation in the main retinal vessels. This is performed with custom-made analysis software.

RESULTS

LIGHT AND DARK: After 30 min in the dark, oxygen saturation in retinal arterioles of healthy volunteers was 92 ± 4% (mean ± SD, n = 15). After 5 min in 80 cd/m(2) light, the arteriolar saturation was 89 ± 5%. The decrease was statistically significant (p = 0.008). The corresponding values for retinal venules were 60 ± 5% in the dark and 55 ± 10% in the light (p = 0.020). Similar results were found after alternating 5 min periods of darkness and light. In a second experiment (n = 19), a significant decrease in retinal vessel oxygen saturation was found in 100 cd/m(2) light compared with darkness but 1 and 10 cd/m(2) light had no significant effect. CENTRAL RETINAL VEIN OCCLUSION: In patients with central retinal vein occlusion, the mean saturation in affected retinal venules was 49 ± 12%, while the mean value for venules in the fellow eye was 65 ± 6% (mean ± SD, p = 0.003, n = 8). The retinal arteriolar saturation was the same in affected (99 ± 3%) and the unaffected (99 ± 6%) eyes. The venous oxygen saturation showed much variation between affected eyes. BRANCH RETINAL VEIN OCCLUSION: Median oxygen saturation in venules affected by branch retinal vein occlusion was 59% (range, 12-93%, n = 22), while it was 63% (23-80%) in unaffected venules in the affected eye and 55% (39-80%) in venules in the fellow eye. The difference was not statistically significant (p > 0.05). There was a significant difference between affected arterioles (median 101%; range, 89-115%) and unaffected arterioles (95%, 85-104%) in the affected eye (p < 0.05, n = 18). CENTRAL RETINAL ARTERY OCCLUSION: In a patient with a day's history of central retinal artery occlusion due to temporal arteritis, the mean arteriolar saturation was 71 ± 9% and 63 ± 9% in the venules. One month later, after treatment with prednisolone, the mean arteriolar saturation was 100 ± 4% and the venous saturation 54 ± 5%. DIABETIC RETINOPATHY: When compared with healthy volunteers (n = 31), patients with all categories of diabetic retinopathy had on average 7-10 percentage points higher saturation in retinal arterioles (p < 0.05 for all categories, n = 6-8 in each category). In venules, the saturation was 8-12 percentage points higher (p < 0.05 for all categories). GLAUCOMA SURGERY: Oxygen saturation in retinal arterioles increased by 2 percentage points on average (p = 0.046, n = 19) with surgery, which lowered intraocular pressure from 23 ± 7 mmHg (mean ± SD) to 10 ± 4 mmHg (p < 0.0001). No other significant changes were found (p ≥ 0.35). DORZOLAMIDE: A significant reduction of 3 percentage points was found in arterioles (p < 0.01) and venules (p < 0.05) when patients with glaucoma or ocular hypertension changed from dorzolamide-timolol combination eye drops to timolol alone (n = 6). No change was found in patients, who started on timolol and switched to the combination therapy (p > 0.05, n = 7).

CONCLUSIONS

Dual wavelength oximetry can be used to non-invasively measure retinal vessel oxygen saturation in health and disease. The results indicate that retinal vessel oxygen saturation is (1) increased in the dark, (2) lower in venules affected by central retinal vein occlusions, (3) variable in branch retinal vein occlusion, (4) lower in retinal arterioles in central retinal artery occlusion, (5) increased in diabetic retinopathy, (6-7) mildly affected by glaucoma surgery or dorzolamide.

Long-term effect of early intervention with single intravitreal injection of bevacizumab followed by panretinal and macular grid photocoagulation in central retinal vein occlusion (CRVO) with macular edema: a pilot study

PURPOSE

To evaluate the effect of single-dose intravitreal bevacizumab followed by panretinal and macular grid laser, early in the course of central retinal vein occlusion (CRVO).

METHODS

It is a prospective, non-randomized, interventional study of nine eyes of nine patients with <10 days origin of CRVO who received 2.5 mg (0.1 ml) intravitreal bevacizumab, followed 3 weeks later by panretinal and macular grid photocoagulation. Its effect on visual acuity and anatomical features of CRVO were studied.

RESULTS

Nine eyes of nine patients (male : female = 8 : 1, mean age 54 years), with <10 days (average 2.67 days) onset of CRVO, received intravitreal bevacizumab within 7 days of presentation (average 3.1 days) followed 3 weeks later by panretinal with macular grid laser. Presenting mean baseline visual acuity was 20/320 (1.2 logarithm of the minimum angle of resolution (LOGMAR) units). All the patients showed rapid improvement in the form of rapid clearance of retinal hemorrhages, decreased optic disc swelling and venous dilation, and tortuosity. Mean final visual acuity was 20/63 (0.5 LOGMAR units). No patient showed conversion from non-ischemic to ischaemic CRVO, recurrence of macular edema, and disc collateral formation.

CONCLUSION

Early intravitreal bevacizumab followed by panretinal and macular grid laser may provide visually and anatomically favourable results in a case of CRVO. It may also obviate the need for repeated injection. It requires a large randomized study to substantiate the results.

Bevacizumab therapy for macular edema in central retinal vein occlusion: Long-term results

Background:

There is no proven effective treatment for vision loss in central retinal vein occlusion (CRVO). Bevacizumab has been reported in small series with limited follow-up, to have a positive effect in reducing cystoid macular edema (CME) and improving vision in CRVO.

Purpose:

To report long-term results with the use of bevacizumab in CRVO.

Materials and Methods:

Prospective interventional case series included 15 patients, serially evaluated with best corrected visual acuity (BCVA), optical coherence tomography (OCT), fluorescein angiography, and tonometry. Results were statistically analyzed.

Results:

Mean follow-up was 12 ± 3.6 months (range, 6–18 months); mean number of injections was 2.2 (range, 1–4) per patient. Statistically significant reduction of macular thickness (P < 0.001) was seen at six weeks (mean, 346 μ); three months (mean, 353 μ); six months (mean, 348 μ); and final follow-up (mean, 342 μ). Significant BCVA improvement was seen at six weeks (mean, 0.27 logMAR), three months (mean, 0.3 logMAR), three months (0.15 logMAR), and final follow-up (mean, 0.21 logMAR) (P = 0.009). Also, 73.3% patients had BCVA improvement at the last follow-up.

Conclusion:

Intravitreal bevacizumab is an effective treatment option for CME in CRVO patients. Reinjections at appropriate timing, based on the OCT findings, are important for better visual outcome.

Retinal vein occlusion: beyond the acute event

Retinal vein occlusion is a major cause of vision loss. We provide an overview of the clinical features, pathogenesis, natural history, and management of both branch retinal vein occlusion and central retinal vein occlusion. Several recent multicenter randomized clinical trials have been completed which have changed the approach to this disorder. Management of retinal vein occlusions can be directed at the underlying etiology or the resulting sequelae. Options include surgical intervention, laser photocoagulation, intravitreal pharmacotherapy, and sustained drug delivery devices.

Oxygen saturation in central retinal vein occlusion

PURPOSE

To test whether oxygen saturation is affected in retinal blood vessels in patients with central retinal vein occlusion (CRVO).

DESIGN

Prospective observational case series.

METHODS

Oxygen saturation of hemoglobin was measured in retinal blood vessels in 10 patients with unilateral CRVO. The duration of CRVO before measurement was from 1 day to about 6 months. Two patients were excluded because of poor quality of oximetry images. The spectrophotometric retinal oximeter is based on a fundus camera. It simultaneously captures images of the retina at 605 nm and 586 nm and calculates optical density (absorbance) of retinal vessels at both wavelengths. The ratio of the 2 optical densities is approximately linearly related to hemoglobin oxygen saturation. Mean oxygen saturation was calculated for first- and second-degree arterioles and venules in both eyes of each patient.

RESULTS

The mean oxygen saturation of hemoglobin in retinal venules was 49% ± 12% (mean ± SD, n = 8) in eyes affected by CRVO and 65% ± 6% in unaffected fellow eyes (P = .003). The mean arteriolar oxygen saturation was 99% ± 3% in CRVO eyes and 99% ± 6% in the fellow eyes. Venular oxygen saturation was variable within and between CRVO eyes.

CONCLUSIONS

Oxygen saturation in retinal venules is lower in eyes with CRVO than in fellow eyes and there is considerable variability within and between CRVO eyes. Arteriolar saturation is the same in CRVO and fellow eyes. Retinal oxygenation is disturbed in CRVO.

Venous retinal flow reperfusion mechanisms following radial optic neurotomy with adjunctive intraocular triamcinolone in central retinal vein occlusion

Background

To evaluate retinal reperfusion, anastomosis, and compensation following radial optic neurotomy for ischemic nonperfused central retinal vein occlusion.

Methods

Prospective, non-comparative, interventional case series of 13 patients with ischemic, nonperfused central retinal vein occlusion who underwent decompression surgery with a radial optic neurotomy and adjunctive intraocular triamcinolone. Patients were followed for 1 year after surgery, and were analyzed in the preoperative and postoperative stages determining: visual acuity by ETDRS chart (LogMar) and retinal thickness with optical coherence tomography. Fluorescein angiography was performed at regular intervals to evaluate the capillary perfusion grade. Intraocular pressure was measured and fundus was examined.

Results

Visual acuity and retinal thickness improved in 10/13 (77%) patients after surgery at 1-year follow-up. Adequate retinal reperfusion was achieved in ten of the 13 eyes. Acute reperfusion occurred in six eyes within 2 weeks of surgery and a shunt vessel at the optic disk developed in four eyes within 4 months. In the remaining three eyes, retinal reperfusion was not observed by fluorescein angiography. No complications were noted in any of the patients.

Conclusion

Surgical decompression promoted mechanical reperfusion of the occluded vessel in 10/13 (77%) cases. In 6/13 patients (46%) reperfusion occurred within 2 weeks of surgery, and in 4/13 patients (31%) collateral vessels formed within 4 months.

Early bevacizumab treatment of central retinal vein occlusion

PURPOSE

To evaluate the change in visual acuity and retinal appearance in patients after early initiation of intravitreal bevacizumab treatment for central retinal vein occlusion (CRVO).

DESIGN

Retrospective, interventional case series.

METHODS

Patients with CRVO of fewer than three months' duration receiving intravitreal bevacizumab as primary treatment were evaluated. Patients received an intravitreal 1.25 mg (0.05 ml) bevacizumab injection. Changes in visual acuity, central macular thickness, venous tortuosity and diameter, and optic disk edema were noted.

RESULTS

Six eyes of five consecutive patients with CRVO treated with intravitreal bevacizumab injection were reviewed retrospectively. The patients did not have other ocular conditions that could have compromised visual acuity. The mean baseline visual acuity was 20/428 (logarithm of the minimum angle of resolution [logMAR] units, 1.33). The mean follow-up period was 12 months (range, seven to 15 months), and the number of bevacizumab injections ranged from four to 10. The patients showed a statistically significant decrease in optic nerve head swelling, venous tortuosity, and venous diameter, with the largest proportion of change occurring within one month of the first bevacizumab injection. The mean visual acuity at last follow-up was 20/53 (logMAR units, 0.42; P = .035, as compared with baseline). In no patient did collateral vessels at the optic nerve head develop.

CONCLUSIONS

The patients experienced a dramatic improvement in the visual acuity and clinical fundus appearance, without collateral vessel formation. These findings are difficult to explain with current theories of the pathophysiologic features of CRVO. These findings also suggest early initiation of anti-vascular endothelial growth factor (VEGF) treatment should be studied in a larger trial for CRVO.

Bevacizumab in retinal vein occlusion-results of a prospective case series

BACKGROUND

Macular edema is the main reason for decreased visual acuity (VA) in early retinal vein occlusion (RVO). Bevacizumab (Avastin, Genentech) is an anti-VEGF substance to treat macular edema triggered by hypoxia-induced expression of vascular endothelial growth factor (VEGF). Initial reports showed a significant reduction of central retinal thickness and improved visual acuity (VA) after bevacizumab injection. To date, only retrospective studies and case reports have been published on bevacizumab treatment of RVO.

METHODS

In this prospective interventional case series, we evaluated the response to a single bevacizumab treatment in 21 RVO patients (14 CRVO, 7 BRVO). Study endpoints were visual acuity (VA) using ETDRS charts and central macular edema (CME) over 9 weeks.

RESULTS

Mean VA from all 21 patients increased by more than 2 lines (2.4+/-0.4 lines; p<0.01 compared to baseline). The improvement of VA after bevacizumab injection was concordant with a decrease in central retinal thickness. Peak VA was reached between 3 and 6 weeks after injection. Between week 6 and 9 a decrease in VA was observed. This VA decrease was precipitated by an increase in CME between week 3 and 6. In subgroup analyses, patients receiving bevacizumab injection within the first 3 months after RVO showed an average VA gain of 4 lines (range 2-7 lines) compared to an average gain of 1.8 (range 1-3) and 2.5 (range 1-7) in patients receiving bevacizumab between 4-6 months and after more than 6 months, respectively.

CONCLUSIONS

Bevacizumab injection is able to improve CME and VA in RVO patients within the first 3 to 9 weeks. We did not observe any short-term adverse effects during our study. As the decrease in VA was anticipated by an increase in central retinal thickness, regular OCT examinations between week 3 and 6 may be helpful for judging the appropriate timing for re-injection in order to maintain patients within the initially reached range of VA until a new balance between inflow and outflow in the retinal circulation is reached.

Radial optic neurotomy for the management of hemicentral retinal vein occlusion: long-term follow-up study

PURPOSE

To assess the efficacy of radial optic neurotomy (RON) for hemicentral retinal vein occlusion (hemi-CRVO) in patients with follow-up of >12 months.

METHODS

Five consecutive patients with hemi-CRVO were enrolled in the study and underwent vitrectomy with RON. The effects of this treatment were assessed by visual acuity, optical coherence tomography, indocyanine green angiography, and kinetic visual field testing.

RESULTS

The median and mean visual acuities improved from 20/250 to 20/50 and from 20/286 to 20/51, respectively. Four patients (80%) had visual acuity improvement of > or =3 lines; visual acuity in 1 patient (20%) remained the same. Visual acuity in all four eyes with preoperative visual acuity of <20/200 improved to >20/200 12 months after surgery. Foveal thickness was gradually reduced during the follow-up period. Chorioretinal anastomosis was detected by indocyanine green angiography in 3 eyes (60%). A temporal visual field defect was found in two eyes. No neovascularization on the iris, angle, optic disk, or retina was detected postoperatively.

CONCLUSION

Visual acuity may improve more with RON compared with the natural history of the disease, and no neovascular formation may occur after RON, suggesting that this procedure may be an effective treatment for hemi-CRVO.

Radial optic neurotomy in central retinal vein occlusion: preliminary results

BACKGROUND

To investigate the efficacy of radial optic neurotomy (RON) on visual prognosis and clinical findings in central retinal vein occlusion (CRVO).

METHODS

Prospective, non-randomised, self-controlled comparative trial. Six patients with ischemic CRVO who had visual acuity (VA) less than or equal to 0.1 and duration of CRVO at least 1 month, and 6 patients with non-ischemic CRVO who maintained their VA less than or equal to 0.1 during the minimal follow-up of 3 months underwent pars plana vitrectomy and RON. LogMAR VA measurement and fluorescein angiography were performed before and after surgery. Automated perimetry was obtained from 4 patients at the last visit. Main outcome measures were VA and clinical changes in fundus appearance of CRVO evaluated with fundus photography and fluorescein angiography.

RESULTS

Radial optic neurotomy was successfully performed in all 12 patients without serious complications. All patients were of clinical improvement of fundus findings. In 11 (92%) patients, a visual improvement of at least 2 lines was observed. After mean follow-up of 9.3 months, mean improvement in VA was 5.1 +/- 3.1 lines (range, 2-14 lines). Cystoid macular oedema and degeneration were observed in 8 (67) patients. Four patients, two of whom had preoperative ocular hypertension had raised intraocular pressure controlled with topical antiglaucoma medication. In late postoperative period, one ischemic eye developed vitreous haemorrhage necessitating vitrectomy and endolaser photocoagulation. Automated perimetry revealed segmental visual field defects in all the examined eyes.

CONCLUSIONS

Radial optic neurotomy in CRVO yields clinical and visual improvement in majority of the patients. Cystoid macular oedema and degeneration are the major factors responsible for restriction of VA improvement. Further randomised and controlled studies with longer follow-up are essential to establish the appropriate timing and indications of RON in CRVO.

Retinal vascular regeneration

We discuss the potential use of stem cells for therapeutic angiogenesis in the treatment of retinal diseases. We demonstrate that the clinical utility of these EPC may be not limited in the treatment of ischemic retinal diseases but may also have application for the treatment of retinal degenerative disorders and for a form of cell-based gene therapy. One of the greatest potential benefits of bone marrow derived EPC therapy is the possible use of autologous grafts. Nonetheless, potential toxicities and unregulated cell growth will need to be carefully evaluated before this approach is brought to the clinics.

Evaluation of radial optic neurotomy for central retinal vein occlusion by indocyanine green videoangiography and image analysis

PURPOSE

To evaluate the effects of radial optic neurotomy (RON) on retinal circulation in patients with central retinal vein occlusion (CRVO) by indocyanine green (ICG) videoangiography and a computer-assisted image analysis.

DESIGN

An interventional case series.

METHODS

RON was performed in 15 eyes of 15 patients with CRVO. Within 72 hours before the surgery and at 3 months after the surgery, ICG videoangiography was performed with a scanning laser ophthalmoscope, and the images were transferred to a computer. Two measurement points were selected, one on a main retinal artery close to the optic disk and the other on the corresponding retinal vein. At each point, fluorescence intensities were serially measured, and dye dilution curves were obtained. Retinal circulation times (DeltaT(50)) before and after the surgery were calculated.

RESULTS

Mean preoperative DeltaT(50) was 6.46 +/- 1.36 seconds, and mean postoperative DeltaT(50) was 6.80 +/- 2.50 seconds. In 8 of 15 eyes, T(50) decreased by 6.8% to 29.6% after the surgery. In the seven eyes that developed chorioretinal anastomosis (CRA) at the site of RON, DeltaT(50) decreased after the surgery. In contrast, DeltaT(50) decreased postoperatively in only one of the eight eyes without CRA. Best-corrected visual acuity improved significantly after the surgery in the group of eyes with improvement in DeltaT(50), but not in the group of eyes without improvement in DeltaT(50).

CONCLUSIONS

Some degree of retinal circulation improvement occurred in approximately half of these eyes, which appears to be correlated with the development of CRA.

Long-term follow-up of a modified technique for laser-induced chorioretinal venous anastomosis in nonischemic central retinal vein occlusion

PURPOSE

To evaluate the long-term outcomes of a modified technique for laser chorioretinal venous anastomosis in nonischemic central vein occlusion (CVO).

DESIGN

Prospective, noncomparative, consecutive case series.

PARTICIPANTS

Nineteen eyes of 19 patients.

METHODS

Nineteen consecutive eyes with nonischemic CVO were observed for a mean period of 48 months after attempted laser-induced chorioretinal venous anastomosis therapy using a technique modified intentionally to avoid vein wall rupture.

MAIN OUTCOME MEASURES

Anastomosis patency, visual acuity, maintenance of nonischemic status, and complications were measured.

RESULTS

At least one patent anastomosis developed eventually in 19 of 19 eyes (100%). Two anastomoses developed in 5 of 19 eyes (26%). There were one or two nonfunctioning sites in 8 of 19 eyes (42%). The maximum number of treatment attempts in a single eye was four. Snellen visual acuity was unchanged in 3 of 19 eyes (16%) and improved from 1 to 11 lines (mean improvement, 5 lines) in 16 of 19 eyes (84%) during the mean follow-up period of 48 months. Nineteen of 19 eyes (100%) maintained nonischemic status. Treatment complications were limited to localized preretinal fibrosis.

CONCLUSIONS

Rupture of the vein wall is not required to form a functioning laser-induced chorioretinal venous anastomosis in eyes with nonischemic CVO. A technique modified intentionally to avoid vein wall rupture seems to be safer and more predicable.

Indocyanine green angiography in chorioretinal diseases: indications and interpretation: an evidence-based update

TOPIC/PURPOSE: To assess the clinical usefulness and relevance of indocyanine green angiography (ICG) in the investigation of chorioretinal disorders and assess specifically in what conditions it may add useful information to that obtained using standard fluorescein angiography.

CLINICAL RELEVANCE

Many publications on ICG have appeared in recent years touting its use in ophthalmology. These publications have led to increasing use of this technique and to its application in numerous retinal diseases in which the fluorescein angiographic findings have been thoroughly described.

METHODS/LITERATURE REVIEWED

During this systematic literature review, we identified and reviewed a total of 376 articles, from among which we selected 92 that we considered most relevant to our purpose of evaluating published evidence as to the efficacy of ICG. We excluded many articles with weak study designs and those that simply duplicated previously published information. Our literature search used PubMed and was confined to articles in English or that included an English abstract.

RESULTS

Our systematic review suggests that ICG has relatively few specific indications for use as justified by previously published peer-reviewed studies. In keeping with the requirements for this Journal's evidence-based articles, we have divided our clinical recommendations for the use of ICG into three categories: (A) strongly recommended and supported by strong evidence; (B) recommended with moderately strong supporting evidence; (C) not recommended at present because supported only by anecdotal or group consensus evidence. We highly recommended ICG for (1) identification of polypoidal choroidal vasculopathy, (2) occult choroidal neovascularization, (3) neovascularization associated with pigment epithelial detachments, and (4) recurrent choroidal neovascular membranes. These are all conditions in which ICG contributes to the identification of lesions that may be treatable. We recommend ICG with some enthusiasm for identifying feeder vessels in age-related macular degeneration, choroidal neovascular membranes, chronic central serous retinopathy, multiple evanescent white dot syndrome, vasculitis, acute multifocal placoid pigment epitheliopathy, Vogt-Koyanagi-Harada syndrome, macular lesions associated with angioid streaks, and birdshot retinopathy. In all these conditions, ICG may help establish a diagnosis and provide some useful guidance for therapy. At present, we do not recommend ICG for scleritis and posterior scleritis, drusen differentiation, Behçet's disease, or sarcoidosis, because it has not been demonstrated to add useful clinical information.

CONCLUSIONS

ICG, although now a well established technique, has clear advantage over fluorescein angiography in relatively few chorioretinal disorders. It has, however, contributed to the understanding of pathologic processes in many ocular diseases. As yet, no published randomized controlled clinical trials show any benefit to the use of ICG in the management of any specific ocular disease.