Chorioretinal Anastomosis After Radial Optic Neurotomy for Central Retinal Vein Occlusion

Guidelines for the Management of Retinal Vein Occlusion by the European Society of Retina Specialists (EURETINA)

The high prevalence of cardiovascular disease particularly in the elderly population is associated with retinal vascular disease. Retinal vein occlusions represent severe disturbances of the hypoxia-sensitive neurosensory retina. Acute and excessive leakage leads to the diagnostic hallmarks of retinal hemorrhage and edema with substantial retinal thickening. Advanced diagnostic tools such as OCT angiography allow to evaluate retinal ischemia and identify the risk for late complications and will soon reach clinical routine besides fluorescein angiography. Accordingly, the duration of non-perfusion is a crucial prognostic factor requiring timely therapeutic intervention. With immediate inhibition of vascular leakage, anti-VEGF substances excel as treatment of choice. Multiple clinical trials with optimal potential for functional benefit or a lesser regenerative spectrum have evaluated aflibercept, ranibizumab, and bevacizumab. As retinal vein occlusion is a chronic disease, long-term monitoring should be individualized to combine maintenance with practicability. While steroids may be considered in patients with systemic cardiovascular risk, surgery remains advisable only for very few patients. Destructive laser treatment is an option if reliable monitoring is not feasible. Ophthalmologists are also advised to perform a basic systemic workup to recognize systemic concomitants. The current edition of the EURETINA guidelines highlights the state-of-the-art recommendations based on the literature and expert opinions in retinal vein occlusion.

Vitrectomy for macular edema due to retinal vein occlusion

Purpose: To determine the long-term outcomes of vitrectomy for the macular edema associated with a retinal vein occlusion (RVO).

Methods: This was a retrospective, consecutive, interventional case series. The intraoperative procedures included internal limiting membrane peeling, arteriovenous sheathotomy, radial optic neurotomy, and intravitreal triamcinolone acetonide injection at the end of the surgery. The main outcome was the best-corrected visual acuity (BCVA).

Results: Eight hundred and fifty-four eyes of 854 patients were studied. The eyes consisted of 602 with branch RVO (BRVO), 74 with hemi-central RVO (hemi-CRVO), 87 with nonischemic central retinal vein occlusion (CRVO), and 91 with ischemic CRVO. The mean follow-up period was 68.6 months with a range of 12 to 262 months. The mean BCVA was significantly improved at the final visit (P<0.0001 to 0.0016). The final BCVA improved in 74.4% of the BRVO eyes, in 58.1% of the hemi-CRVO eyes, in 57.4% of the nonischemic CRVO eyes, and in 51.6% of the ischemic CRVO eyes. Multiple regression analysis showed there was no significant relationship between the intraoperative combined procedures and the final BCVA.

Conclusions: The results indicate that the type of RVO is significantly associated with the final BCVA, and vitrectomy is a treatment option to improve and maintain BCVA for a long term.

[Management of macular edema secondary to retinal vein occlusion]

BACKGROUND

In recent years, intravitreal injections have added to the treatment modalities available for macular edema (ME) secondary to retinal vein occlusion (RVO). This article aims to provide an update regarding the management of ME secondary to RVO.

METHODS

A work group met in order to analyze the literature available on Embase/PubMed, regarding treatments for venous occlusion that have received market approval and are reimbursed in France. In total, 33 articles were selected. Consensus within the group for recommendations was based on this data from the literature review and clinical experience and was reported in this article.

RESULTS

The management of ME secondary to branch retinal vein occlusion (BRVO) or central vein occlusion of the retina (CRVO) differs on a number of points. Methods of best practice were discussed separately for BRVO and CRVO, taking into account various ocular and associated parameters.

DISCUSSION

Ranibizumab and dexamethasone implant are the first-line treatments for visual impairment due to ME secondary to RVO. The choice of either of these drugs may take into account various ocular and extraocular parameters. A change of treatment to one or the other or to laser may also be considered during follow-up.

Ocular vascular occlusive disorders: natural history of visual outcome

Ocular vascular occlusive disorders collectively constitute the most common cause of visual disability. Before a disease can be managed, it is essential to understand its natural history, so as to be able to assess the likely effectiveness of any intervention. I investigated natural history of visual outcome in prospective studies of 386 eyes with non-arteritic anterior ischemic optic neuropathy (NA-AION), 16 eyes with non-arteritic posterior ischemic optic neuropathy, 697 eyes with central retinal vein occlusion (CRVO), 67 eyes with hemi-CRVO (HCRVO), 216 eyes with branch retinal vein occlusion (BRVO), 260 eyes with central retinal artery occlusion (CRAO), 151 eyes with branch retinal artery occlusion (BRAO) and 61 eyes with cilioretinal artery occlusion (CLRAO). My studies have shown that every one of these disorders consists of multiple distinct clinical sub-categories with different visual findings. When an ocular vascular occlusive disorder is caused by giant cell arteritis, which is an ophthalmic emergency, it would be unethical to do a natural history study of visual outcome in them, because in this case early diagnosis and immediate, intensive high-dose steroid therapy is essential to prevent any further visual loss, not only in the involved eye but also in the fellow, normal eye. In NA-AION in eyes seen ≤2 weeks after the onset, visual acuity (VA) improved in 41% of those with VA 20/70 or worse, and visual field (VF) improved in 26% of those with moderate to severe VF defect. In non-ischemic CRVO eyes with VA 20/70 or worse, VA improved in 47% and in ischemic CRVO in 23%; moderate to severe VF defect improved in 79% in non-ischemic CRVO and in 27% in ischemic CRVO. In HCRVO, overall findings demonstrated that initial VA and VF defect and the final visual outcome were different in non-ischemic from ischemic HCRVO - much better in the former than the latter. In major BRVO, in eyes with initial VA of 20/70 or worse, VA improved in 69%, and moderate to severe VF defect improved in 52%. In macular BRVO with 20/70 or worse initial VA, it improved in 53%, and initial minimal-mild VF defect was stable or improved in 85%. In various types of CRAO there are significant differences in both initial and final VA and VF defects. In CRAO eyes seen within 7 days of onset and initial VA of counting fingers or worse, VA improved in 82% with transient non-arteritic CRAO, 67% with non-arteritic CRAO with cilioretinal artery sparing, 22% with non-arteritic CRAO. Central VF improved in 39% of transient non-arteritic CRAO, 25% of non-arteritic CRAO with cilioretinal artery sparing and 21% of non-arteritic CRAO. Peripheral VF improved in non-arteritic CRAO in 39% and in transient non-arteritic CRAO in 39%. In transient CRAO, finally peripheral VFs were normal in 93%. In non-arteritic CRAO eyes initially 22% had normal peripheral VF and in the rest it improved in 39%. Final VA of 20/40 or better was seen in 89% of permanent BRAO, and in 100% of transient BRAO and non-arteritic CLRAO. In permanent BRAO eyes, among those seen within 7 days of onset, central VF defect improved in 47% and peripheral VF in 52%, and in transient BRAO central and peripheral VFs were normal at follow-up. My studies showed that AION, CRVO, BRVO, CRAO and BRAO, each consist of multiple distinct clinical sub-categories with different visual outcome. Contrary to the prevalent impression, these studies on the natural history of visual outcome have shown that there is a statistically significant spontaneous visual improvement in each category. The factors which influence the visual outcome in various ocular vascular occlusive disorders are discussed.

The ABCs of RVO: a review of retinal venous occlusion

Retinal vein occlusions are important causes of loss of vision; indeed, they are the second most common retinal vascular disease, following diabetic retinopathy. For this reason alone, primary eye-care providers must be well versed in diagnosis and management. Risk factors, though not universally agreed upon, include but are not limited to advancing age, systemic hypertension, arteriolarsclerosis, diabetes, hyperlipidaemia, blood hyperviscosity, thrombophilia, ocular hypertension and glaucoma. Typically, visual loss is secondary to macular oedema and/or retinal ischaemia. Treatment modalities have included observation, systemic thrombolysis and haemodilution, radial optic neurotomy, chorioretinal anastomosis, vitrectomy, laser photocoagulation and intravitreal injection of anti-inflammatory and, most recently, anti-vascular endothelial growth factors.

A prospective, randomised, multicenter trial for surgical treatment of central retinal vein occlusion: results of the Radial Optic Neurotomy for Central Vein Occlusion (ROVO) study group

BACKGROUND

To compare the surgical outcomes and evaluate the effectiveness of two treatments for central retinal vein occlusion (CRVO), radial optic neurotomy (RON) and intravitreal triamcinolone (IVT), in comparison to natural history.

METHODS

A prospective, placebo-controlled, randomised and multi-center study. Patients with CRVO were treated in three groups - with either RON, a single intravitreal injection of 4 mg triamcinolone acetonide, or a placebo treatment. The main outcome measures were change of VA (visual acuity) and proportion of eyes with a significant improvement (defined as > 3 lines logMAR scale) of VA from baseline to month 12.

RESULTS

Ninety patients were included. Due to insufficient data, seven were excluded. Forty-seven percent (n = 18) of patients treated with RON showed an increase in VA, in comparison to 10 % (n = 2) of placebo-treated patients, and 20 % (n = 5) of patients treated with IVT. Significantly more patients showed an improvement in VA following RON than in the placebo group (p = 0.009). Significantly more patients showed an improvement in VA following RON than in the IVT group (p = 0.034). No significant difference was found when directly comparing improvement in VA following IVT and placebo (p = 0.667) treatment.Significantly (p = 0.007) more patients in the placebo group (35 %, n = 7) showed a deterioration (defined as > 3 lines LogMAR scale) in VA than patients in the RON group (8 %, n = 3).

CONCLUSION

Our study showed that following treatment with RON, patients with CRVO display a significantly better long-term VA than untreated patients and patients treated with a single dose of IVT.

Therapeutic benefit of radial optic neurotomy in a rat model of glaucoma

Radial optic neurotomy (RON) has been proposed as a surgical treatment to alleviate the neurovascular compression and to improve the venous outflow in patients with central retinal vein occlusion. Glaucoma is characterized by specific visual field defects due to the loss of retinal ganglion cells and damage to the optic nerve head (ONH). One of the clinical hallmarks of glaucomatous neuropathy is the excavation of the ONH. The aim of this work was to analyze the effect of RON in an experimental model of glaucoma in rats induced by intracameral injections of chondroitin sulfate (CS). For this purpose, Wistar rats were bilaterally injected with vehicle or CS in the eye anterior chamber, once a week, for 10 weeks. At 3 or 6 weeks of a treatment with vehicle or CS, RON was performed by a single incision in the edge of the neuro-retinal ring at the nasal hemisphere of the optic disk in one eye, while the contralateral eye was submitted to a sham procedure. Electroretinograms (ERGs) were registered under scotopic conditions and visual evoked potentials (VEPs) were registered with skull-implanted electrodes. Retinal and optic nerve morphology was examined by optical microscopy. RON did not affect the ocular hypertension induced by CS. In eyes injected with CS, a significant decrease of retinal (ERG a- and b-wave amplitude) and visual pathway (VEP N2-P2 component amplitude) function was observed, whereas RON reduced these functional alterations in hypertensive eyes. Moreover, a significant loss of cells in the ganglion cell layer, and Thy-1-, NeuN- and Brn3a- positive cells was observed in eyes injected with CS, whereas RON significantly preserved these parameters. In addition, RON preserved the optic nerve structure in eyes with chronic ocular hypertension. These results indicate that RON reduces functional and histological alterations induced by experimental chronic ocular hypertension.

Early histologic and functional study of radial optic neurotomy outcomes in normal rat eyes

BACKGROUND

Radial optic neurotomy (RON) has been proposed as a treatment for central retinal vein occlusion. However, it is still under debate whether RON would be an adequate treatment or a dangerous procedure, and persuasive animal studies are lacking. The aim of this study was to analyze the early histologic and functional outcomes of RON in normal rat eyes.

METHODS

Radial optic neurotomy was performed by cutting into the optic nerve edge at the nasal hemisphere, while the contralateral eye underwent a sham procedure. The retinal function was assessed by scotopic electroretinography, and the visual pathway was assessed by flash visual evoked potentials. Intraocular pressure was assessed with a tonometer, the pupillary light reflex was measured after exposing eyes to a 30-second light flash, whereas the optic nerve head structure was examined by histologic analysis.

RESULTS

In normal rat eyes, RON provoked minor histologic alterations at the optic nerve head level and a transient decrease in the electroretinography. No changes in visual evoked potentials, intraocular pressure, and pupillary light reflex were observed in rat eyes submitted to RON.

CONCLUSION

To our knowledge, this is the first study describing the early histopathologic and functional consequences of RON in normal rat eyes.

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.

[Long-term clinical outcome of radial optic neurotomy]

PURPOSE

To study the long-term clinical outcome through assessment of anatomical and functional results, as well as complications of eyes affected with central retinal vein occlusion (CRVO) that underwent radial optic neurotomy (RON).

METHODS

Retrospective, observational and descriptive study of 47 eyes corresponding to 47 patients affected by CRVO. All the eyes underwent RON performed by the same surgeon since 2002. The main assessed variables were visual acuity (VA), intraocular pressure (IOP), presence of iris neovascularization and opticocilliary veins, vascular recanalization and complications derived from this pathological entity.

RESULTS

Surgery was performed in 47 eyes, 21 of them (44.7%) were right sided and 26 left sided (55.3%). Mean age was 58.97 years. Mean post-surgical follow-up was 32.15 months. A total of 70.2% of the patients experienced stabilization or VA improvement, 23.4% iridian neovascularisation and 42.6% developed opticocilliary veins in the head of the optical nerve.

CONCLUSIONS

It is noticeable that in selected cases, RON produces a quick resolution of the retinal haemorrhage and papillary congestion and may improve the retinal perfusion. Long-term benefits are stabilization or improvement of the VA and a reduction in complications on the natural history in CRVO.

[SERV clinical practice guidelines: management of retinal vein occlusion. Sociedad Española de Retina y Vitreo]

PURPOSE

A guidelines for the management of retinal vein occlusion is presented. This is necessary because at this moment several therapeutic alternatives have been developed although their role is not yet sufficiently defined.

METHODS

Review of the literature for evidence published up to date. Relevant literature was identified and the level of evidence graded. Evidence was then assessed for consistency, applicability and clinical impact. The information was contrasted with those guides published in other countries.

RESULTS

Taking into account the different options of treatment that are currently used, several modes of action are suggested. The role of the various complementary examinations are discussed and it is recommended that criteria for the treatment are based on clinical, angiographic, and tomographic findings.

CONCLUSIONS

Although there is no overall consensus, these guidelines promote a good standard of clinical practise and provide an update of the management of retinal vein occlusion.

Natural history of visual outcome in central retinal vein occlusion

OBJECTIVE

To investigate systematically the natural history of visual outcome in central retinal vein occlusion (CRVO).

DESIGN

Cohort study.

PARTICIPANTS

Six hundred sixty-seven consecutive patients (30 patients had both eyes involved resulting in 697 eyes) with CRVO first seen in the authors' clinic from 1973 through 2000.

METHODS

At the first visit, all patients underwent a detailed ophthalmic and medical history and a comprehensive ophthalmic evaluation. Visual evaluation was carried out by recording visual acuity, using the Snellen visual acuity chart, and assessing visual fields with a Goldmann perimeter. The same ophthalmic evaluation was performed at each follow-up visit. Central retinal vein occlusion was classified into nonischemic (588 eyes) and ischemic (109 eyes) types at the initial visit based on functional and morphologic criteria.

MAIN OUTCOME MEASURES

Visual acuity and visual fields.

RESULTS

Of the eyes first seen within 3 months, visual acuity was 20/100 or better in 78% with nonischemic CRVO and in only 1% with ischemic CRVO (P < 0.0001), and visual field defects were minimal or mild in 91% and 8%, respectively (P < 0.0001). Final visual acuity, on resolution of macular edema, was 20/100 or better in 83% with nonischemic CRVO and in only 12% with ischemic CRVO (P < 0.0001), and visual field defects were minimal or mild in 95% and 18%, respectively (P < 0.0001). On resolution of macular edema, in eyes with initial visual acuity of 20/70 or worse, visual acuity improved in 59% with nonischemic CRVO, with no significant (P = 0.55) improvement in ischemic CRVO. Similarly, on resolution of macular edema, in eyes with moderate to severe initial visual field defect, improvement was seen in 86% of nonischemic CRVO eyes, but no significant (P = 0.83) improvement was seen in eyes with ischemic CRVO. In nonischemic CRVO, development of foveal pigmentary degeneration, epiretinal membrane, or both, was the main cause of poor final visual acuity. This shows that initial presentation and the final visual outcome in the 2 types of CRVO are entirely different.

CONCLUSIONS

A clear differentiation of CRVO into nonischemic and ischemic types, based primarily on functional criteria, is crucial and fundamental in determining visual outcome. Visual outcome is good in nonischemic CRVO and poor in ischemic 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.

Ultrastructural analysis of the lamina cribrosa after radial optic neurotomy

Radial optic neurotomy (RON) has been proposed for alleviation of the "scleral outlet compartment syndrome" at the level of the lamina cribrosa, which is thought to play a pathoetiologic role in central retinal vein occlusion (CRVO). The aim of this study has been to analyze the ultrastructural alterations of the lamina cribrosa after RON to gain new insights in the underlying pathomechanical factors. Fifteen donor eyes underwent a standardized open-sky-vitrectomy and RON after removal of the anterior eye segment for keratoplasty. Using a microvitreoretinal blade, a radial incision was performed on the nasal hemisphere of the optic nerve head radial to the optic disc and parallel to the nerve fibre layer. The lamina cribrosa and the surrounding scleral ring were then prepared for light microscopy, scanning (SEM) and transmission electron microscopy (TEM). Ultrastructural analysis demonstrated that in 60% (n=9) of the evaluated cases the scleral ring was dissected completely and in 40% (n=6) only partially. The adjacent neuronal tissue to the dissection area showed only minimal injury. The central retinal vessels were not injured in all cases. Only complete incision of the circular ring of collagen fibrils surrounding the lamina cribrosa via RON resulted in effective relaxation of the scleral outlet and was achieved in 60% of all eyes under standardized conditions. In all cases the adjacent tissue showed only minimal injury. The high rate of incomplete dissection of the scleral outlet may be an explanation for the variable outcome seen in different studies on RON.

Radial optic neurotomy for central retinal vein occlusion: results of the Pan-American Collaborative Retina Study Group (PACORES)

OBJECTIVE

To evaluate the complications after radial optic neurotomy (RON) for central retinal vein occlusion (CRVO).

METHODS

Seventy-three consecutive patients (73 eyes) with CRVO who were treated with RON participated in a retrospective, uncontrolled, interventional, multicenter case series at 7 institutions from 6 countries.

RESULTS

In the ischemic CRVO group (n = 53), 32% of eyes had an improvement in best-corrected visual acuity (BCVA) (mean, 5.5 lines), 35.8% had worse BCVA (mean, 6.4 lines), and 32% had BCVA that remained the same after RON. In the nonischemic CRVO group (n = 20), 50% of eyes had an improvement in BCVA (mean, 6.5 lines), 15% had worse BCVA (mean, 4.3 lines), and 35% had BCVA that remained the same after RON. Complications occurred in 71.2% of cases, including cataract in 17 eyes (23.2%), vitreous hemorrhage in 16 eyes (20.5%), persistent macular edema in 15 eyes (20.5%), neovascular glaucoma in 7 eyes (9.5%), anterior segment neovascularization in 5 eyes (6.8%), retinal detachment in 3 eyes (4.1%), and phthisis bulbi, choroidovitreal neovascularization, central retinal artery perforation, and optic nerve atrophy in 1 eye (1.3%) each.

CONCLUSIONS

RON may improve visual acuity in some eyes with CRVO, but complications are common. In our series, surgery by itself did not seem to improve the outcome of CRVO when compared with its natural history.

Surgical treatment of central retinal vein occlusion

The treatment of central retinal vein occlusion (CRVO) is still a subject of debate. Medical therapy efforts, as well as retinal laser photocoagulation, have mostly dealt with management of the sequelae of CRVO, and have shown limited success in improving visual acuity. The unsatisfactory results of such therapeutic efforts led to the development of new treatment strategies focused on the surgical treatment of the occluded retinal vein. The purpose of this review is to summarize the outcomes of commonly reported surgical treatment strategies and to review different opinions on the various surgical approaches to the treatment of CRVO.

Treatment of central retinal vein occlusion by radial optic neurotomy in 107 cases

BACKGROUND

To evaluate the potential role of radial optic neurotomy (RON), a new surgical technique has been recently proposed for treating central retinal vein occlusion (CRVO). It is hypothesized that CRVO constitutes a neurovascular compartment syndrome at the site of the lamina cribrosa, which can be alleviated by performing a radial incision at the nasal part of the optic nerve head, relaxing the cribriform plate and the adjacent sclera.

METHODS

One hundred and seven patients were treated with RON for CRVO at five collaborating ophthalmologic centers. All patients were evaluated by a standardized protocol. For analysis of the angiographic and fundus findings, reference images were used. Intraoperative and postoperative complications were reviewed.

RESULTS

On 55 right and 52 left eyes of 107 patients (55.6% male, 44.4% female) with a median age of 68 years (range 21-91 years), RON was performed. The median follow-up time was 6 months (range 1-24 months). The median preoperative visual acuity (VA) was 0.05 (logMAR 1.3), increasing to a median postoperative VA of 0.08 (logMAR 1.1). Patients with an interval of more than 90 days between RON and onset of CRVO showed no significant change in VA at the 6-month follow-up. Severe peripapillary swelling of the optic nerve head prior to RON resulted in an average increase of 4.2 lines in VA at the 6-month follow-up. Angiographic findings of shunt vessels were seen in 18/30 cases after 12 months and were accompanied by an average improvement of VA of six lines. Visual field tests showed various defects in 86.8% of all cases. In one patient an iatrogenic injury of the central retinal artery occurred (0.9%).

CONCLUSION

Despite the potential risk of visual field defects, RON seems to be a quite safe procedure. The majority of patients showed rapid normalization of the morphologic fundus findings, with an improvement in VA uncommon for the natural history of CRVO. No significant change in VA was seen in patients with an interval of more than 90 days between the onset of CRVO and RON. A prospective study is warranted for further investigation.

Changes of electroretinogram without improvement of retinal circulation after radial optic neurotomy for central retinal vein occlusion. ERG changes after RON for CRVO

PURPOSE

To evaluate the efficacy of radial optic neurotomy (RON) on retinal function in patients with central retinal vein occlusion (CRVO).

METHODS

Ten eyes of 10 patients with CRVO underwent pars plana vitrectomy and RON. Standardized combined electroretinograms (ERGs) to full-field bright-flash stimuli were recorded preoperatively and, 3 months postoperatively. The best-corrected visual acuity and foveal thickness were also determined, before and 3 months postoperatively.

RESULTS

The mean best-corrected visual acuity and mean foveal thickness were both significantly improved after vitrectomy and RON. The mean amplitudes of a- and b-waves did not change significantly, but the mean b/a wave ratio was increased significantly after vitrectomy and RON. An improvement of the b/a ratio was observed in six eyes, however, an improvement of retinal circulation was confirmed on postoperative fluorescein angiograms in two of these six eyes.

CONCLUSIONS

Significant improvements were observed in the b/a wave ratio of the standard combined ERGs after surgery in eyes with CRVO. The improvement of retinal function was most likely due to improved oxygenation of retina caused by vitrectomy and not by RON.

Biomechanical Assessment of Radial Optic Neurotomy

PURPOSE

A biomechanical model was constructed to simulate the potential therapeutic effect that the surgical procedure radial optic neurotomy (RON) would have on an eye with a central retinal vein occlusion.

DESIGN

Experimental study.

CONTROLS

Model eyes undergoing RON were compared to control eyes under the same baseline conditions.

INTERVENTION

Radial optic neurotomy. We modeled the optic nerve, lamina cribrosa, and the sclera separately and then reassembled the components. Material properties of the sclera and lamina cribrosa were extracted from the literature and both stiff and more elastic values were used for the optic nerve. Intraocular and arterial pressures were varied across a wide range in the analysis.

MAIN OUTCOME MEASURE

Change in central retinal vein lumen size.

RESULTS

Over a clinically relevant range of boundary conditions, the increase in the lumen area of the central retinal vein lumen after RON remained trivial, ranging from 1% to a maximum of 5%.

CONCLUSIONS

The biomechanical effect of RON is negligible, and is unlikely to be a procedure that could mechanically ameliorate the clinical sequelae of a central vein occlusion.

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.

Peripapillary haemorrhagic retinal pigment epithelium detachment following radial optic neurotomy

Central retinal vein occlusion is a common vascular cause of blidness. In this paper, we first report focal haemorrhagic pigment epithelium detachment and chorioretinal anastomosis in the peripapillary area as an intraoperative complication of radial optic neurotomy (RON). A 65-year-old white man presented with ischaemic central vein occlusion OS. He underwent vitrectomy with RON, panretinal photocoagulation and intravitreal injection of triamcinolone acetonide. A circumscribed subretinal haemorrhage was noted intraoperatively at the nasal site of the RON. The haemorrhage size decreased at the seventh postoperative day when an optical coherence tomography scan disclosed a haemorrhagic pigment epithelium detachment. Fluorescein angiography and fundus photograph revealed a chorioretinal anastomosis formation nasal to the optic nerve confirmed by indocyanine green angiography. Best-correlated visual acuity improved from hand movements to 6/18 at the fourth week and it was stable until last examination. This case illustrates the role of chorioretinal anastomosis formation in the vision improvement following RON.

Patients' preferences in choosing therapy for retinal vein occlusions

PURPOSE

The purpose of this study was to assess preference values for vein occlusions with macular edema and to determine how this may affect patient perceptions of potential treatments.

METHODS

The Submacular Surgery Trials Vision Preference Value Scale and questions regarding enthusiasm for potential treatments were administered to 153 patients with vein occlusion. Univariate analyses identified predictors of preference values, followed by adjustment for potential confounders using multivariate linear regression. Relationships between preference values and enthusiasm for potential treatments were assessed.

RESULTS

The mean preference values +/- SD were similar for patients with branch vein occlusions and central vein occlusions (0.65 +/- 0.20). Lower preference values were associated with duration of occlusion of >2 years (P=0.03) and poorer last-recorded visual acuity (P=0.02). Approximately one half of patients were moderately or very enthusiastic about undergoing intravitreal injection. Sixty-nine percent of branch vein occlusion patients were moderately or very enthusiastic about the standard of care, laser photocoagulation; only one third of central vein occlusion patients were moderately or very enthusiastic about standard observation.

CONCLUSIONS

These data suggest that vein occlusion with macular edema has a significant impact on quality of life. Most patients were willing to undergo potentially invasive treatment.

Long-term effects of radial optic neurotomy for central retinal vein occlusion consecutive interventional case series

PURPOSE

To investigate the long-term (minimum 24 months follow-up) clinical results of radial optic neurotomy (RON) following a pars plana vitrectomy (PPV) with internal limiting membrane peeling as treatment for central retinal vein occlusion (CRVO).

METHODS

Interventional case series of 14 consecutive patients (14 eyes) with CRVO who were treated with a PPV combined with RON within 1 year of diagnosis.

RESULTS

Median baseline visual acuity (VA) was 1.05 logMAR (approximately 0.09 Snellen) in the affected eye. The follow-up period ranged from 24 to 48 months postoperatively, median 30 months. At the 24-month follow-up examination, median VA was 1.005 logMAR in the affected eye-a significant improvement (p = 0.013). Six patients (43%) gained 1 or more lines of VA (mean VA gain = 1.7 lines), while the VA of four patients (29%) improved by 3 or more lines. The eyes with nonischemic CRVO demonstrated a significantly higher improvement in VA (p = 0.0007) than the eyes with ischemic CRVO.

CONCLUSION

With RON clinically relevant improvements on a long-term basis seem achievable. Patients with nonischemic CRVO may respond more favorably than patients with ischemic CRVO.

Long-term visual outcomes of vitrectomy for cystoid macular edema due to nonischemic central retinal vein occlusion

PURPOSE

To report the long-term surgical outcome of vitrectomy for cystoid macular edema due to nonischemic central retinal vein occlusion (CRVO).

METHODS

A retrospective chart review of 25 consecutive eyes (25 patients) with cystoid macular edema due to nonischemic CRVO treated with vitrectomy was performed. All patients underwent a pars plana vitrectomy with the creation of a posterior vitreous detachment if still attached. Simultaneous phacoemulsification with intraocular lens implantation was also performed in phakic eyes. The main outcome measures were best-corrected visual acuity (BCVA) and changes in macular edema shown by contact-lens biomicroscopy. The mean follow-up time was 49 months (range, 16-108).

RESULTS

The median BCVA before surgery was 0.31 and the median BCVA at last follow-up was 0.67. The BCVA at the last follow-up improved at least two Snellen lines in 17 (68%), remained unchanged in 4 (16%), and worsened in 4 (16%). The BCVA was 20/40 or better in 3 eyes (12%) preoperatively and in 18 eyes (72%) at the last follow-up. During the follow-up, four patients progressed to ischemic CRVO; one of them had neovascular glaucoma requiring surgical intervention.

CONCLUSION

The data indicate that vitrectomy appears to be a possibly effective treatment in some eyes with cystoid macular edema associated with nonischemic CRVO.

Interventions for Central Retinal Vein Occlusion

TOPIC

To assess the evidence for the effectiveness of interventions to improve visual acuity (VA) and prevent or treat neovascularization secondary to central retinal vein occlusion (CRVO).

CLINICAL RELEVANCE

Central retinal vein occlusion is a common cause of visual morbidity and blindness. Many different interventions have been advocated, but the evidence justifying their use remains unclear.

METHODS/LITERATURE REVIEWED

English and non-English language articles were retrieved using a keyword search of Medline (1966 onwards), Embase, the Cochrane Collaboration, the National Institutes of Health Clinical Trials database, and the Association for Research in Vision and Ophthalmology (2003-2005). This was supplemented by manually searching references of review articles. Two investigators independently identified all randomized clinical trials (RCTs) on interventions in CRVO with more than 3 months' follow-up.

RESULTS

Of 4133 citations retrieved, 17 RCTs comparing intervention with a control group were identified. There were 4 RCTs on laser photocoagulation. Grid macular laser photocoagulation did not improve VA in CRVO with macular edema. Prophylactic panretinal photocoagulation did not prevent angle and iris neovascularization in ischemic CRVO, but resulted in regression of angle and iris neovascularization and reduced progression to neovascular glaucoma. There were 4 RCTs that reported improvement in VA with inpatient hemodilution, 2 RCTs with no significant improvement, and 1 RCT showing deterioration in VA after outpatient hemodilution. Randomized clinical trials evaluating ticlodipine, troxerutin, and streptokinase showed a limited or no benefit.

CONCLUSIONS

This review found limited level I evidence for any intervention to improve VA in patients with CRVO. Panretinal photocoagulation resulted in regression of neovascularization. Hemodilution may improve vision in some patients, but the data conflict. More robust randomized controlled trials evaluating current treatments for CRVO are needed. The results of ongoing RCTs on intravitreal triamcinolone, anti-vascular endothelial growth factor agents, and chorioretinal anastomosis are awaited with interest.

Radial optic neurotomy in central retinal vein occlusion: comparison of outcome in younger vs older patients

PURPOSE

To evaluate the effectiveness of radial optic neurotomy (RON) for central retinal vein occlusion (CRVO) in patients < or =50 years of age (group 1) vs those >50 (group 2).

DESIGN

Prospective, interventional, comparative case series.

METHODS

The study included 43 consecutive patients with CRVO and preoperative visual acuity (VA) < or =0.70 logarithm of minimal angle of resolution (logMAR). All patients underwent pars plana vitrectomy and RON at the nasal border of the optic disk. VA and optical coherence tomography (OCT) findings were recorded preoperatively and at one, six, and 12 months postoperatively.

RESULTS

Systemic hypertension, diabetes, and open-angle glaucoma were statistically significantly more prevalent in group 2 (P < .05). One patient in group 1 had hyperhomocysteinemia, and had another antiphospholipid syndrome. Fifty percent of patients in group 1 gained > or =3 lines of Early Treatment Diabetic Retinopathy Study (ETDRS) vision, vs 33% in group 2. Mean final VA was 0.5 logMAR VA in group 1 vs 0.8 in group 2 (P = .04). Foveal thickness decreased significantly in both groups (P < .001). Ten patients (55.6%) in group 1 and 13 (54.2%) in group 2 developed retinochoroidal collaterals.

CONCLUSIONS

Underlying systemic disease does not seem to be an important factor in the pathogenesis of CRVO in younger patients, and thrombophilia was present in only 11% of patients in this age group. RON yielded better functional results in younger patients, although functional improvement remained limited in those with low baseline VA.

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.

The management of retinal vein occlusion: is interventional ophthalmology the way forward?

Retinal vein occlusions (RVO) are the second commonest sight threatening vascular disorder. Despite its frequency treatments for RVO are unsatisfactory and include several that have not been tested by large, well designed, prospective, randomised controlled trials. There is also the lack of long term follow up in many of the available small uncontrolled studies, and the timings of interventions are haphazard. This review aims to evaluate the current knowledge relating to the pathogenesis, suggested treatments for the different types of RVO, and their complications. Isovolaemic haemodilution is of limited benefit and should be avoided in patients with concurrent cardiovascular, renal, or pulmonary morbidity. Evidence to date does not support any therapeutic benefit from radial optic neurotomy, optic nerve decompression, or arteriovenous crossing sheathotomy on its own. Vitrectomy combined with intravenous thrombolysis may offer promise for central RVO. Similarly, vitrectomy combined with arteriovenous sheathotomy intravenous tissue plasminogen activator may offer benefits for branch RVO. RVOs occur at significantly high frequency to allow future prospective randomised controlled studies to be conducted to evaluate the role of different therapeutic modalities singly or in combination.

Visual Field Defect After Radial Optic Neurotomy for Central Retinal Vein Occlusion

PURPOSE

To evaluate visual field defects after radial optic neurotomy (RON) in eyes with central retinal vein occlusion (CRVO).

METHODS

Eight patients (eight eyes) underwent RON for macular edema associated with CRVO. Goldmann perimetry was performed on each patient both before and after surgery.

RESULTS

Postoperative Goldmann perimetry showed a temporally located wedge-shaped visual field defect consistent with neural damage secondary to RON in seven eyes (88%). After surgery, the visual field decreased from preoperative values by 7% at 3 months (P = 0.30) and by 21% at 12 months (P = 0.0023). Although three patients (38%) were aware of the postoperative visual field defect, only one patient (13%) considered this defect to be a visual disability.

CONCLUSIONS

After RON, most patients showed a postoperative defect in the temporal visual field consistent with the incision to the optic disk. However, this visual field defect appears to be well tolerated by most patients.

Wie tief muss die radiäre Optikusneurotomie zur Therapie des retinalen Zentralvenenverschlusses sein?

PURPOSE

Most of the studies on radial optic neurotomy (RON) have not defined the depth of the incision. Complications following a deeper incision have been described. This histological study was performed to evaluate the required depth for RON.

METHODS

Serial sections of the area of the optic nerve head were performed in 19 eye bank eyes. The distance between the inner surface of the optic disc and the outer limit of the cribriform plate was measured. Ten additional eye bank eyes underwent 2 mm deep experimental RON using the Spaide CRVO Knife (DORC, Netherlands). The cutting depth was assessed histologically by serial cuts.

RESULTS

The distance between the inner surface of the disc and the outer limit of the cribriform plate measured 1.35+/-0.3 mm (shrinkage-revised value: 1.45 mm). The experimental RON showed cutting depths of 1.53+/-0.3 mm (shrinkage-revised value: 1.65 mm).

CONCLUSION

Based on normal eyes, a cutting depth of 1.45 mm is sufficient to cut through the cribriform plate. This might change during central retinal vein occlusion because possible papillary edema due to central retinal vein occlusion has to be considered. Even under controlled experimental conditions RON leads to great variation in incision depths. The development of a knife with a fixed penetration depth would be helpful.

Comparative evaluation of radial optic neurotomy and panretinal photocoagulation in the management of central retinal vein occlusion

PURPOSE

There is currently no treatment proven effective for central retinal vein occlusion (CRVO). Radial optic neurotomy (RON) has recently surfaced as a new treatment for the disorder, however, and we compare here the visual acuity (VA) and arteriovenous transit time (AVTT) following RON and panretinal photocoagulation (PRP).

METHODS

We conducted a retrospective, uncontrolled study of 27 patients. Of 27 eyes diagnosed with CRVO, 16 were treated with panretinal photocoagulation (PRP) and 11 with RON. VA and fluorescein angiography were used to monitor the evolution of CRVO, and for follow-up.

RESULTS

All patients underwent PRP or RON with no major complications. The difference between pre- and post-operative VA was not statistically significant for either group (p=0.092 on PRP; p=.0081 on RON). The change in AVTT was also not statistically significant for either group (p= 0.024 on PRP; p=0.027 on RON). Ultimately, we found no statistically-significant difference in comparing VA and AVTT for the two groups (p =0.074 on VA; p=0.510 on AVTT).

CONCLUSIONS

No evidence supporting the effectiveness of RON could be found in this study, suggesting that surgical decompression by RON may not be effective for treating CRVO. Further studies regarding the efficacy of RON should be made.

Histopathologic findings after radial optic neurotomy in central retinal vein occlusion

PURPOSE

Radial optic neurotomy (RON) in central retinal vein occlusion (CRVO) is a novel strategy that is aimed at relief of mechanical pressure on the central retinal vein. We report on histopathologic findings in a human eye 18 weeks after RON.

DESIGN

Interventional case report.

METHODS

Eighteen weeks after RON for ischemic CRVO, an eye was enucleated because of neovascular glaucoma and examined histologically.

RESULTS

Histopathologic evidence demonstrated displaced fragments of Bruch's membrane surrounded by retinal tissue at the nasal side of the papilla. A discrete scar was noted at this site that reached the cribriform plate without involving the adjacent sclera or the retinal vessels. The optic nerve showed advanced atrophy with a small temporal sector of viable nerve fibers.

CONCLUSIONS

Histopathologic findings after RON do not provide evidence for the postulated mechanism of action. It appears prudent to further evaluate this technique before its general implementation in the management of CRVO.

Retinal blood flow and macular edema after radial optic neurotomy for central retinal vein occlusion

PURPOSE

To determine the effect of radial optic neurotomy (RON) on retinal blood flow (RBF) and macular edema in eyes with a central retinal vein occlusion.

DESIGN

Prospective interventional study.

METHODS

Seven eyes of seven patients with central retinal vein occlusion underwent RON and vitrectomy and were followed for at least 6 months. The RBF was calculated from dye dilution curves of video fluorescein angiograms. The foveal thickness was determined by optical coherence tomography.

RESULTS

At 1 week after surgery, the RBF was significantly reduced from 28.5 +/- 5.4 to 21.1 +/- 6.6 pixel(2)/s (P < .01). At 6 months after surgery, the RBF (26.0 +/- 7.7 pixel(2)/s) was not significantly different from the preoperative RBF, although chorioretinal anastomoses were found in all seven eyes. The foveal thickness was significantly decreased from 711 +/- 271 to 488 +/- 182 mum (P = .03). The postoperative visual acuity was better than the preoperative visual acuity by two or more lines in three out of seven eyes, and was worse in two eyes.

CONCLUSIONS

Neither RON nor chorioretinal anastomoses improved the RBF but macular edema was improved. These findings suggest that removal of the vitreous could reduce macular edema as in diabetic macular edema. However, we cannot exclude the possibility that the changes represent the natural course of this disease.

CHARACTERISTICS OF VISUAL FIELD DEFECTS BY SCANNING LASER OPHTHALMOSCOPE MICROPERIMETRY AFTER RADIAL OPTIC NEUROTOMY FOR CENTRAL RETINAL VEIN OCCLUSION

PURPOSE

To evaluate visual field defects after radial optic neurotomy (RON) for the treatment of central retinal vein occlusion (CRVO) by using scanning laser ophthalmoscope microperimetry.

METHODS

Thirteen eyes of 13 patients with severe vision loss (< or = 20/200) from CRVO who underwent pars plana vitrectomy and RON had postoperative Goldmann kinetic perimetry, scanning laser ophthalmoscope microperimetry, and fluorescein angiographic evaluation.

RESULTS

After a mean follow-up of 8 months, 6 of the 13 patients had visual improvement by > or = 2 lines. Eight patients developed an anastomosis at the radial cut. Postoperatively, sectorial visual field loss arising from the optic head was found by Goldmann perimetry in six patients, and a thin nerve fiber bundle defect was found in three patients. Four patients had no detectable visual field defect shown by Goldmann perimetry, but microperimetry demonstrated an absolute nerve fiber bundle defect arising from the radial cut at the optic disk for three of these patients.

CONCLUSION

Visual field loss after RON for the treatment of CRVO is a frequent complication. The etiology of this visual loss appears to be a combination of mechanical trauma to the nerve fiber layers and ischemia of the optic disk circulation.

Massive hemorrhagic retinal detachment during radial optic neurotomy

BACKGROUND

We encountered obvious arterial bleeding from the incision site during radial optic neurotomy (RON) in a 55-year-old woman with central retinal vein occlusion (CRVO) and report the findings herein.

CASE REPORT

The patient initially demonstrated a retinal hemorrhage and macular edema due to a left CRVO. Her corrected visual acuity was 0.5 OS. Since her symptoms did not improve and were aggravated, even though she received an oral anticoagulant drug orally, RON was performed 2 months after the onset of symptoms. During surgery, obvious arterial bleeding started from the RON incision site and it was not arrested although the infusion bottle was fully elevated. However, a subsequent infusion of liquid perfluoro-carbon successfully stopped the bleeding by direct pressure. Hemorrhagic retinal detachment occurred in the nasal quadrant and postoperative vitreous hemorrhage was treated surgically. The hemorrhagic retinal detachment was gradually absorbed and replaced by fibrous scar tissue. Two years after the surgery, no expansion of retinal detachment has been observed and corrected visual acuity is being maintained at 0.2 OS.

CONCLUSION

We conclude that RON for CRVO carries a risk of arterial bleeding and that infusion of liquid perfluoro-carbon seems to be effective to arrest arterial bleeding from the RON site.

Prevalent misconceptions about acute retinal vascular occlusive disorders

Acute retinal vascular occlusive disorders collectively constitute one of the major causes of blindness or seriously impaired vision, and yet there is marked controversy on their pathogeneses, clinical features and particularly their management. This is because the subject is plagued by multiple misconceptions. These include that: (i) various acute retinal vascular occlusions represent a single disease; (ii) estimation of visual acuity alone provides all the information necessary to evaluate visual function; (iii) retinal venous occlusions are a single clinical entity; (iv) retinal vein occlusion is essentially a disease of the elderly and is not seen in the young; (v) central retinal vein occlusion (CRVO) is one disease; (vi) fluorescein fundus angiography is the best test to differentiate ischemic from nonischemic CRVO; (vii) the site of occlusion in CRVO is invariably at the lamina cribrosa; (viii) clinical picture of CRVO is often due to compression or strangulation of the central retinal vein (CRV) in the lamina cribrosa and not its occlusion; (ix) an eye can develop both CRVO and central retinal artery occlusion (CRAO) simultaneously; (x) every eye with CRVO is at risk of developing neovascular glaucoma; (xi) lowering intraocular pressure (IOP) helps to improve retinal circulation in an eye with CRVO; (xii) every patient with retinal vein occlusion should have complete hematologic and coagulation evaluation; (xiii) the natural history of CRVO does not usually involve spontaneous visual improvement; (xiv) management of CRVO is similar to that of venous thrombosis anywhere else in the body, i.e. with aspirin and/or anti-coagulants; (xv) fibrinolytic agents can dissolve an organized thrombus in the CRV; (xvi) it is beneficial to lower blood pressure in patients with CRVO; (xvii) panretinal photocoagulation used in ischemic retinal venous occlusive disorders has no deleterious side-effects; (xviii) glaucoma or ocular hypertension can cause branch retinal vein occlusion; (xix) branch retinal vein occlusion can cause neovascular glaucoma; (xx) in eyes with CRAO, the artery is usually not completely occluded; (xxi) CRAO is always either embolic or thrombotic in origin; (xxii) amaurosis fugax is always due to retinal ischemia secondary to transient retinal arterial embolism; (xxiii) asymptomatic plaque(s) in retinal arteries do not require a detailed evaluation; (xxiv) retinal function can improve even when acute retinal ischemia due to CRAO has lasted for 20h or more; (xxv) CRAO, like ischemic CRVO, can result in development of ocular neovascularization; (xxvi) panretinal photocoagulation is needed for "disc neovascularization" in CRAO; (xxvii) fibrinolytic agents are the treatment of choice in CRAO; (xxviii) there is no chance of an eye with retinal arterial occlusion having spontaneous visual improvement; (xxix) absence of any abnormality on Doppler evaluation of the carotid artery or echography of the heart always rules out those sites as the source of embolism; and (xxx) absence of an embolus in the retinal artery means the occlusion was not caused by an embolus. The major cause of all these misconceptions is the lack of a proper understanding of basic scientific facts related to the various diseases. The objective of this paper is to discuss these misconceptions, based on these scientific facts, to clarify the understanding of these blinding disorders, and to place their management on a rational, scientific basis.

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.

Radial optic neurotomy for ischaemic central vein occlusion

BACKGROUND/AIMS

Ischaemic central retinal vein occlusion (CRVO) accounts for 20-50% of all CRVO. No treatment has been proved to be effective. The efficacy of radial optic neurotomy (RON) was evaluated in eyes with ischaemic CRVO.

METHODS

10 patients with ischaemic CRVO underwent RON. After pars plana vitrectomy, a microvitreoretinal blade was used to incise the scleral ring, cribriform plate, and adjacent sclera at the nasal edge of the optic disc. Best corrected visual acuity (BCVA), intraocular pressure (IOP), fluorescein angiography (FA), multifocal electroretinography (mfERG), and optical coherence tomography (OCT) were measured preoperatively and at 1, 3, and 6 months postoperatively.

RESULTS

No visual improvement was noted in the eyes that underwent RON. FA and mfERG showed no increase in retinal perfusion or retinal function postoperatively. Mean macular central thickness changed from 841 (SD 170) mum preoperatively to 162 (SD 34) microm at the sixth postoperative month. One patient had retinal central artery perforation intraoperatively. One patient developed neovascular glaucoma.

CONCLUSION

RON in ischaemic CRVO did not improve visual function (by mfERG) or visual acuity although macular thickness did improve. This technique may be associated with potential risks. Randomised studies are needed to corroborate these results.