Anterior ischaemic optic neuropathy. Differentiation of arteritic from non-arteritic type and its management

Nonarteritic anterior ischemic optic neuropathy and incidence of Parkinson's disease based on a nationwide population based study

This study aimed to investigate the association between nonarteritic anterior ischemic optic neuropathy (NAION) and Parkinson's disease (PD) using a retrospective, nationwide, population-based cohort in South Korea. This study utilized data from the Korean National Health Insurance database, including 43,960 NAION patients and 219,800 age- and sex-matched controls. Cox proportional hazards regression models were used to assess the risk of developing PD in the NAION group compared to the control group after adjusting for various confounding factors. Subgroup analyses were conducted based on sex, age, and comorbidities. The incidence rate of PD was higher in the NAION group (1.326 per 1000 person-years) than in the control group (0.859 per 1000 person-years). After adjusting for confounding factors, the risk of developing PD was significantly higher in the NAION group (adjusted hazard ratio [aHR] 1.516, 95% confidence interval [CI] 1.300-1.769). Subgroup analyses did not reveal a significant difference in the risk of PD development based on sex, age, or comorbidities. This retrospective, nationwide, population-based cohort study revealed a significant association between NAION and an increased risk of developing PD in a South Korean population. The incidence rate of PD was observed to be higher in individuals diagnosed with NAION than in age- and sex-matched controls even after adjusting for potential confounding variables, with the risk being approximately 51.6% higher in the NAION group. Further research is necessary to elucidate the underlying pathophysiological mechanisms linking NAION to PD and to determine whether similar associations exist in other ethnic and geographical populations.

A case of cilioretinal artery occlusion: Diagnostic procedures

Purpose

To evaluate characteristic imaging findings and functional outcomes of Cilioretinal Artery Occlusion (CLRAO) associated with giant cell arteritis (GCA).

Observations

We report the case of a 70-year-old woman presenting with sudden vision loss caused by a GCA-associated-CLRAO in her left eye (LE). A thorough ophthalmologic examination together with optical coherence tomography (OCT), OCT-Angiography (OCT-A), fluorescein angiography and fundus autofluorescence were performed. At presentation, the best corrected visual acuity in the LE was 20/200 and funduscopic examination revealed optic disc edema associated with retinal whitening along the area perfused by the CLRA. After 1 month, OCT and OCT-A revealed an improvement of the retinal edema and a partial reduction of the non-perfused areas in the superficial and deep capillary plexuses, as well as in the outer retina and in the choriocapillaris. Fluorescein angiography showed a reduction in the perfusion of the affected area, a delayed perfusion of the temporal sector of the optic disc, as well as areas of choroidal hypoperfusion in the peripheral temporal retina. The patient's visual acuity did not change during the follow up.

Conclusion and importance

Despite a partial recanalization of the occluded vasculature being possible after GCA-associated-CLRAO, the patient's visual prognosis remains poor.

Paracentral Acute Middle Maculopathy as a Specific Sign of Arteritic Anterior Ischemic Optic Neuropathy

PURPOSE

The purpose of this study is to assess the diagnostic accuracy of paracentral acute middle maculopathy (PAMM) in the setting of anterior ischemic optic neuropathy (AION) to distinguish arteritic (A-AION) from nonarteritic (NA-AION) type.

DESIGN

Retrospective cross-sectional diagnostic evaluation.

METHODS

PAMM was evaluated by 3 physicians blinded to diagnosis using macular spectral-domain optical coherence tomography. We studied 45 patients with AION. Of those, 28 had NA-AION and 17 had A-AION. The study was conducted in the Department of Ophthalmology at the Hospital of Marseille-Assistance Publique, France, from January 1, 2018, to March 31, 2022.

RESULTS

PAMM were only found in the A-AION group (N = 4) (P = .0143). As a distinctive sign of A-AION, we found a specificity of 100% (95% IC, 88.06%-100%) and a positive predictive value of 100%. In contrast, sensitivity and negative predictive value were lower, 19.1% (95% IC, 5.5-42.0) and 63.0% (95% CI, 58.1-67.7), respectively.

CONCLUSIONS

The PAMM finding is highly specific for A-AION in the setting of AION. According to our results, macular spectral-domain optical coherence tomography looking for PAMM should be performed with any patient presenting with AION.

Vascular supply of the optic nerve head: implications for optic disc ischaemia

The vascular supply of the optic nerve head is complex and remains incompletely delineated. Over the past 50 years, various investigators have attempted to clarify the relative contributions of the choroid, the short posterior ciliary arteries and the central retinal artery to the vascular beds of the inner retinal, prelaminar, laminar and retrolaminar segments of the nerve head. Conflicting theories have evolved, in no small part due to differing techniques of study, involving both flow parameters and anatomical constructs. These have included studies, both in normal subjects and in those with optic nerve ischaemia, of histopathology, electron microscopic corrosion casting, orbital colour Doppler flow studies, fluorescein angiography, indocyanine green angiography, laser Doppler flow studies, laser speckle flowgraphy, microperfusion and labelling studies and optical coherence tomography angiography. The nature of the optic disc, peripapillary retina and choroid microvasculature has implications for the pathophysiology of ischaemic optic neuropathy.

Sectoral Sparing Associated With a Cilioretinal Artery in Arteritic Anterior Ischemic Optic Neuropathy

ABSTRACT

Giant cell arteritis (GCA) is a life-threatening vasculitis occurring in older adults that can cause blindness by ischemia of the choroid, retina, and optic nerve. We report a case of a patient who presented with "occult" GCA with severe anterior ischemic optic neuropathy affecting both optic nerves, delayed choroidal filling, and a concomitant cilioretinal artery occlusion in the left eye. The retinal territory supplied by the affected cilioretinal artery was hypoperfused, yet this retinal territory at least partially corresponded to the only preserved visual field in that eye. The sector of the optic disc corresponding to the emergence of the cilioretinal artery was the only sector spared by pallid edema. This pattern of sectoral sparing associated with a cilioretinal artery has been observed in other patients with GCA and in animal models of posterior ciliary artery occlusion. This case serves as a clear example of an incompletely understood phenomenon in posterior pole circulation in vascular occlusive disease that deserves further study.

Diagnosis and management of giant cell arteritis: Major review

Giant cell arteritis is a medical emergency because of the high risk of irreversible blindness and cerebrovascular accidents. While elevated inflammatory markers, temporal artery biopsy and modern imaging modalities are useful diagnostic aids, thorough history taking and clinical acumen still remain key elements in establishing a timely diagnosis. Glucocorticoids are the cornerstone of treatment but are associated with high relapse rates and side effects. Targeted biologic agents may open up new treatment approaches in the future.

Association Study of MTHFR Polymorphisms with Nonarteritic Anterior Ischemic Optic Neuropathy in a Spanish Population

Introduction

Nonarteritic anterior ischemic optic neuropathy (NAION), painless loss of central and/or peripheral vision, is a multifactorial disease caused by insufficient blood flow through the posterior ciliary arteries to the optic nerve head. Mutations in the methylenetetrahydrofolate reductase (MTHFR) gene, triggering hyperhomocysteinemia as a consequence of a decreased activity of the codified enzyme, have been considered to be among the risk factors of NAION.

Objective

The main aim was to study the association of the most common MTHFR genetic polymorphisms C677T and A1298C with NAION in a Spanish population.

Methods

In this case-control study, the association of the most common MTHFR polymorphisms was investigated in 94 unrelated native Spanish patients diagnosed with NAION and 204 healthy controls. Two single nucleotide polymorphisms located in the MTHFR gene, C677T (rs1801133) and A1298C (rs1801131), were analyzed by DNA sequencing and TaqMan assays.

Results

The allelic and genotypic frequencies of the MTHFR variants obtained in the NAION group were not significantly different when compared with the control group. A higher frequency of the C677T/A1298C genotype, codifying the nonmutated MTHFR form, was obtained in control subjects (11.27%) compared to NAION patients (4.26%), suggesting a protective effect of the wild-type protein, although this result was not conclusive considering the obtained confidence interval (CI) (95% CI: 0.13-1.06). Study of additional clinical factors including hypertension, diabetes mellitus, and dyslipidemia showed no association with a higher risk of NAION. Conversely, the clinical history of heart or cerebrovascular diseases was significantly higher in NAION patients compared to controls. Over the world, risk variants of the MTHFR gene are highly frequent, excluding African black populations, indicating a racial influence.

Conclusions

The MTHFR variants did not significantly increase the risk of suffering from NAION. However, considering that individuals with at least one of the risk variants have the MTHFR enzyme with decreased activity, it cannot be ruled out that these mutations are relevant for the development of NAION in a subgroup of the population with other specific characteristics. These may include high plasma levels of homocysteine along with nutritional deficiencies including low folate or vitamin B12 and the combination of systemic and local risk factors.

Unraveling the Enigma of Nonarteritic Anterior Ischemic Optic Neuropathy

Non-arteritic anterior ischemic optic neuropathy (NAON) is the second most common optic neuropathy in adults. Despite extensive study, the etiology of NAION is not definitively known. The best evidence suggests that NAION is caused by an infarction in the region of the optic nerve head (ONH), which is perfused by paraoptic short posterior ciliary arteries (sPCAs) and their branches. To examine the gaps in knowledge that defies our understanding of NAION, a historical review was performed both of anatomical investigations of the ONH and its relevant blood vessels and the evolution of clinical understanding of NAION. Notably, almost all of the in vitro vascular research was performed prior our current understanding of NAION, which has largely precluded a hypothesis-based laboratory approach to study the etiological conundrum of NAION. More recent investigative techniques, like fluorescein angiography, have provided valuable insight into vascular physiology, but such light-based techniques have not been able to image blood vessels located within or behind the dense connective tissue of the sclera and laminar cribrosa, sites that are likely culpable in NAION. The lingering gaps in knowledge clarify investigative paths that might be taken to uncover the pathogenesis of NAION and possibly glaucoma, the most common optic neuropathy for which evidence of a vascular pathology also exists.

Window to the circulatory system: Ocular manifestations of cardiovascular diseases

The changes in the cardiovascular system are associated with ocular manifestations, often as a consequence of pathological alteration in the ocular vasculature. The ease of visualization of these retinal changes makes the eye a window to the cardiovascular system. Certain congenital cardiac defects lead to changes in the retinal vascularity due to increased tortuosity and dilatation. In adults, the arterial dissection of internal carotid and vertebral arteries present as amaurosis fugax with or without oculo-sympathetic palsy. The patients with untreated infective endocarditis present with Roth spots, retinitis, embolic retinopathy, or sub-retinal abscesses. Hypoperfusive, hypertensive, or "mixed" retinopathy is a hallmark sign in patients of untreated infective endocarditis. Giant cell arteritis can present with ischemic ocular symptoms that may precipitate in irreversible vision loss. Systemic vascular manifestations such as coronary artery disease may manifest in a wide range of symptoms from amaurosis fugax to vision loss depending upon the size and location of retinal emboli. Rare cardio-oncological pathologies such as myxomas result in vision loss secondary to central retinal artery occlusion. A high clinical suspicion in patients with history of cardiovascular diseases can help in early diagnosis and management of impending, adverse cardiovascular and cerebrovascular events. In this review, we comprehensively discuss the spectrum of cardiac and vascular diseases with ocular manifestations as well as highlight the typical ocular presentations associated with these pathologies.

A neuroglia-based interpretation of glaucomatous neuroretinal rim thinning in the optic nerve head

Neuroretinal rim thinning (NRR) is a characteristic glaucomatous optic disc change. However, the precise mechanism of the rim thinning has not been completely elucidated. This review focuses on the structural role of the glioarchitecture in the formation of the glaucomatous NRR thinning. The NRR is a glia-framed structure, with honeycomb geometry and mechanically reinforced astrocyte processes along the transverse plane. When neural damage selectively involves the neuron and spares the glia, the gross structure of the tissue is preserved. The disorganization and loss of the glioarchitecture are the two hallmarks of optic nerve head (ONH) remodeling in glaucoma that leads to the thinning of NRR tissue upon axonal loss. This is in contrast to most non-glaucomatous optic neuropathies with optic disc pallor where hypertrophy of the glioarchitecture is associated with the seemingly absent optic disc cupping. Arteritic anterior ischemic optic neuropathy is an exception where pan-necrosis of ONH tissue leads to NRR thinning. Milder ischemia indicates selective neuronal loss that spares glia in non-arteritic anterior ischemic optic neuropathy. The biological reason is the heterogeneous glial response determined by the site, type, and severity of the injury. The neuroglial interpretation explains how the cellular changes underlie the clinical findings. Updated understandings on glial responses illustrate the mechanical, microenvironmental, and microglial modulation of activated astrocytes in glaucoma. Findings relevant to the possible mechanism of the astrocyte death in advanced glaucoma are also emerging. Ultimately, a better understanding of glaucomatous glial response may lead to glia-targeting neuroprotection in the future.

The Utility of Fundus Fluorescein Angiography in Neuro-Ophthalmology

While its use is still widespread within the medical retina field, fundus fluorescein angiography (FFA) is increasingly falling out of favour in the investigation of neuro-ophthalmological disease, with the introduction of new technologies, particularly optical coherence tomography. FFA does, however, provide useful diagnostic and prognostic information in many neuro-ophthalmological diseases including papilloedema, pseudo-papilloedema, optic neuropathies and central retinal artery occlusion to name a few. We aim to summarise the main FFA findings in each of these conditions and highlight where FFA is of most use in providing complementary information to other modes of investigation.

Waking Up Blind in the ICU: A Case Report of Ischemic Optic Neuropathy in a Burn Patient

The objective of this report is to analyze and summarize the current literature of ischemic optic neuropathy (ION), a rare complication in severe burn and trauma victims, while presenting an urban burn center's experience with the condition. This is an unfortunate condition and this report will raise awareness to a potential complication in the burn patient population as well as in critically ill patients in other settings.

We present the case of a 27-year-old healthy male patient admitted to our Burn Center with 85% total body surface area (TBSA) full-thickness burns sustained in a house fire. The patient had a complicated hospital course but improved over time and was weaned off of prolonged ventilation and sedation. Subsequently, he complained of bilateral blindness. A fundoscopic examination demonstrated bilateral pale optic nerves with sparing of the remaining peripheral retina consistent with ION. The patient suffered complete bilateral vision loss. He had multiple factors that could have instigated the development of ION, including several episodes of septicemia, hypovolemic shock and severe adult respiratory distress syndrome (ARDS) with refractory hypoxemia requiring a prolong ventilation support and vasopressor therapy. 

Due to the advancement of the treatment of acute burns, the survival rate of patients that once would have succumbed to their burn injury, is increasing. With these new achievements, we are facing new challenges and complications. ION has a significant impact on the quality of the patient’s life. The early diagnosis will not necessarily translate into a benefit for these patients as no treatment has been proven successful. Extensive retrospective and prospective studies are necessary to identify and treat this patient population.

Ocular Hemodynamics in Acute Nonarteritic Anterior Ischemic Optic Neuropathy Compared With Normal Tension Glaucoma

PURPOSE

The purpose of this study was to evaluate ocular hemodynamics in patients with a disease believed to be related to a chronic vascular damage [ie, normal tension glaucoma (NTG)] in comparison with an entity with an acute ischemic impact on the optic nerve [ie, acute nonarteritic anterior ischemic optic neuropathy (NAION)].

MATERIALS AND METHODS

Blood-flow velocities [peak systolic velocity (PSV), enddiastolic velocity (EDV)] of the ophthalmic artery (OA), central retinal artery (CRA), and nasal and temporal posterior ciliary arteries were measured using color Doppler imaging. Resistive index (RI) of all vessels was calculated (PSV-EDV/PSV). A total of 41 patients suffering from acute NAION (onset of symptoms <10 d) and 64 age-matched patients suffering from NTG were included in this prospective study.

RESULTS

No significant differences were recorded for either age or intraocular pressure inbetween the 2 groups. Systolic blood pressure was significantly higher in the NAION group, whereas no significant differences were recorded for the diastolic blood pressure. Only 3 color Doppler imaging parameters were found to differ significantly. The PSV (P<0.005) and EDV (P<0.02) in the CRA were significantly higher in NTG patients. Furthermore, the RI in the OA was significantly higher in the NAION patients (P<0.005).

CONCLUSIONS

Decreased blood-flow velocities in the CRA and a higher RI in the OA can be recorded in NAION patients as compared with NTG. No differences with regard to the posterior ciliary arteries' velocities were recorded. Ocular hemodynamics are suspected to play a critical role in NAION and NTG, whereas the blood-flow disturbances seem to be more severe in NAION than in NTG.

Cilioretinal artery hypoperfusion and its association with paracentral acute middle maculopathy

BACKGROUND/AIMS

To study the multimodal imaging findings of a large series of eyes with cilioretinal artery obstruction (CILRAO) and describe the systemic associations.

METHODS

Multicentre, retrospective chart review from 12 different retina clinics worldwide of eyes with CILRAO, defined as acute retinal whitening in the distribution of the cilioretinal artery, were identified. The clinical, systemic information and multimodal retinal imaging findings were collected and analysed.

RESULTS

A total of 53 eyes of 53 patients with CILRAO were included in the study. In 100% of eyes, fundus photography illustrated deep retinal whitening corresponding to the course of the cilioretinal artery. Twenty-eight patients (52.8%) presented with isolated CILRAO (baseline best-corrected visual acuity (BCVA) 20/50, final BCVA 20/25) associated with nocturnal hypotension, 23 patients (43.4%) with CILRAO secondary to central retinal vein occlusion (CRVO) (baseline BCVA 20/40, final BCVA 20/20) and two patients with CILRAO due to biopsy-proven giant cell arteritis (GCA) (baseline BCVA 20/175, final BCVA 20/75). With spectral domain optical coherence tomography (SD-OCT), a hyper-reflective band involving the inner nuclear layer (ie, paracentral acute middle maculopathy or PAMM) was noted in 51 eyes (28/28 eyes with isolated CILRAO and 23/23 eyes with CILRAO+CRVO) corresponding to the retinal whitening. In the two eyes with CILRAO+GCA, SD-OCT illustrated hyper-reflective ischaemia of both the middle and inner retina.

CONCLUSIONS

Isolated CILRAO and CILRAO secondary to CRVO are the result of hypoperfusion or insufficiency, rather than occlusion, of the cilioretinal artery and are associated with PAMM or selective infarction of the the inner nuclear layer. With GCA, there is complete occlusion of the cilioretinal artery producing ischaemia involving both the middle and inner retina associated with worse visual outcomes.

Quantitative analysis of optical coherence tomographic angiography (OCT-A) in patients with non-arteritic anterior ischemic optic neuropathy (NAION) corresponds to visual function

Purpose

Non-arteritic anterior ischemic optic neuropathy (NAION) is the most common cause of non-glaucomatous optic neuropathy in older adults. Optical coherence tomographic angiography (OCT-A) is an emerging, non-invasive method to study the microvasculature of the posterior pole, including the optic nerve head. The goal of this study was to assess the vascular changes in the optic nerve head and peripapillary area associated with NAION using OCT-A.

Design

Retrospective comparative case series.

Methods

We performed OCT-A in 25 eyes (7 acute and 18 non-acute) in 19 patients with NAION. Fellow, unaffected eyes were analyzed for comparison. Patent macro- and microvascular densities were quantified in the papillary and peripapillary regions of unaffected, acutely affected, and non-acutely affected eyes and compared across these groups according to laminar segment and capillary sampling region, and with respect to performance on automated visual field testing.

Results

In acutely affected eyes, OCT-A revealed a reduction in the signal from the major retinal vessels and dilation of patent superficial capillaries in the peripapillary area. By contrast, non-acutely affected eyes showed attenuation of patent capillaries. The peripapillary choriocapillaris was obscured by edema in acute cases, but was similar between non-acute and unaffected eyes. The degree of dilation of the superficial microvasculature in the acute phase and attenuation in the non-acute phase each correlated inversely with visual field performance. The region of reduced patent capillary density correlated with the location of visual field defects in 80% of acute cases and 80% of non-acute cases.

Conclusions

OCT-A reveals a dynamic shift in the superficial capillary network of the optic nerve head with strong functional correlates in both the acute and non-acute phases of NAION. Further study may validate OCT-A as a useful adjunctive diagnostic tool in the evaluation of ischemic optic neuropathy.

Anterior Ischaemic Optic Neuropathy in Wegener's Granulomatosis

Is reported a case of Wegener's granulomatosis originally presenting with a clinical picture of temporal arteritis. The presentation included an arteritic anterior ischaemic optic neuropathy occurring with no demonstrable orbital inflammation. The treatment of these two systemic vasculitides is quite different, however, and this case emphasizes the importance of questioning the original diagnosis if the clinical course of the disease does not progress as anticipated.

Neuro-Ophthalmic Complications of Biopsy-Proven Giant Cell Arteritis

Purpose

To define the spectrum of neuro-ophthalmic complications and clinical presentations of patients with giant cell arteritis (GCA).

Methods

Retrospective study (1977-1994) of clinical charts, fundus photographies and fluorescein angiographies of 66 patients with temporal artery biopsy positive for GCA.

Results

Clinical data were adquate for 47 patients. Headaches were reported by 83%, weight loss in 73%, jaw claudication in 68%, scapular pain in 64% and asthenia in 57%. Erythrocyte sedimentation rate was normal in 15%. Neuro-ophthalmic complications were present in 33 cases (70%), including anterior ischemic optic neuropathy (22 cases), choroidal ischemia (17 cases), central or branch retinal artery occlusion (seven cases), and oculomotility disturbances (four cases). Fluorescein angiography was very helpful for detecting choroidal ischemia (80.9% of our cases). Twenty-one patients presented with involvement of several distinct orbital arterial territories and one very unusual patient suffered from an orbital infarction (i.e. ischemia of all orbital structures).

Conclusions

In our series, two-thirds of biopsy-proven GCA patients presented with neuro-ophthalmic complications, ranging from transient visual loss to orbital infarction. Involvement of more than one orbital vascular territory is highly suggestive of an arteritic process. Clinicians should keep in mind the possibility of GCA even when ESR is normal, and fluorescein angiography should be performed. The finding of choroidal ischemia should prompt temporal artery biopsy and steroid therapy.

Retrobulbar and intraocular blood flow in anterior ischaemic optic neuropathy are linked to the functional impairment

PURPOSE

Evaluation of ocular haemodynamics in patients with acute non-arteritic anterior ischaemic optic neuropathy (NAION) by colour Doppler imaging and fluorescein angiography and correlation of blood flow parameters to visual field loss and visual acuity.

METHODS

Blood flow velocities (peak systolic velocity (PSV), end-diastolic velocity (EDV)) of the ophthalmic artery (OA), central retinal artery (CRA) and nasal and temporal posterior ciliary arteries (PCAs) were measured via colour Doppler imaging. Resistive index (RI) of all vessels was calculated (PSV-EDV/PSV). Retinal arteriovenous passage times (AVP) were evaluated using fluorescein angiography (scanning laser ophthalmoscope) and digital image analysis. The visual field global index mean deviation (MD, 30-2 programme, Humphrey Field Analyzer) and visual acuity (logMar) was used for analysis of functional impairment after NAION.

RESULTS

Twenty patients (age: 64.62 ± 11.63 years) with acute NAION were included. Mean duration of symptoms was 7.6 ± 6.9 days. Mean defect was 15.4 ± 8.9 dB, AVP was determined with 1.66 ± 0.37 s. EDV of the CRA was significantly correlated to visual field MD (r = 0.52, p = 0.017) and AVP (r = - 0.49, p = 0.025). The RI of the OA was significantly correlated to visual acuity (r = 0.493, p < 0.037). No significant correlations were recorded for the PCAs. A significant correlation was found between AVP and the EDV of the CRA (r = - 0.49, p = 0.025).

CONCLUSION

Decreased EDV in the CRA and increased RI in the OA seem to be linked to the functional damage in NAION. An improvement of the retrobulbar circulation might be beneficial in the treatment of NAION.

Role of Thrombocytosis in Diagnosis of Giant Cell Arteritis and Differentiation of arteritic from Non-Arteritic Anterior Ischemic Optic Neuropathy

Purpose

To investigate the role of thrombocytosis in the diagnosis of giant cell arteritis (GCA), and differentiation of arteritic (A-AION) from non-arteritic (NA-AION) anterior ischemic optic neuropathy; and comparison of the sensitivity and specificity of platelet count to that of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and some other hematologic variables in the diagnosis of GCA.

METHODS

This retrospective study is based on 121 temporal artery biopsy confirmed GCA patients and 287 patients with NA-AION seen in our clinic. For inclusion in this study, all GCA patients, at their initial visit, prior to the initiation of corticosteroid therapy, must have had ESR (Westergren), platelet count and complete blood count, and temporal artery biopsy. From 1985 onwards CRP estimation was done. For inclusion in this study, all NA-AION patients at the initial visit must have undergone evaluation similar to that described above for GCA, except for temporal artery biopsy. Wilcoxon rank-sum test and the two-sample t-test were used to compare hematologic variables between GCA patients with and without visual loss, between those with and without systemic symptoms, and also between GCA and NA-AION patients. Pearson correlation coefficient was computed to measure the association of platelet counts and the other hematologic variables with ESR. Receiver operating characteristic (ROC) curves were constructed for ESR, CRP, platelet count, combinations of ESR and platelet count, and CRP and platelet count, hemoglobin, hematocrit, and white blood cell (WBC) count and the area under the curve (AUC) were compared.

Results

Comparison of ESR, CRP, and hematologic variables of GCA patients and of A-AION with the NA-AION group, showed significantly (p <0.0001) higher median levels of ESR, CRP, platelet count, and WBC count and lower levels of hemoglobin and hematocrit in the GCA patients and A-AION than in NA-AION. Comparing AUC of the ROC curve between ESR and platelet count, ESR was a better predictor of GCA compared to platelet count (AUC of 0.946 vs. 0.834). There was a slight improvement in prediction of GCA using the combination of ESR and platelet count (AUC=0.953). The other hematologic variables had an AUC that was smaller than platelet count (0.854 for hemoglobin; 0.841 for hematocrit), with WBC being the least predictive of GCA (AUC=0.666). The AUC of the ROC curve for CRP was 0.978. There was no improvement in prediction of GCA using platelet count in combination with CRP (AUC=0.976).

CONCLUSIONS

Patients with GCA had significantly (p <0.0001) higher values of platelet count, ESR, CRP and WBC but lower values for hemoglobin and hematocrit compared to the NA-AION group. Predictive ability of an elevated platelet count did not surpass elevated ESR or CRP as a diagnostic marker for GCA. Thrombocytosis may complement ESR. Hemoglobin, hematocrit and WBC were much less predictive of GCA. Elevated CRP had a greater predictive ability for GCA compared to ESR or the other hematologic parameters; thrombocytosis in combination with CRP did not yield an improvement in prediction of GCA.

Review of the association between retinal microvascular characteristics and eye disease

Computerized retinal imaging technologies enable the static and dynamic measurement of a range of retinal microvascular parameters. Large population-based studies have reported associations between these microvascular indices and various ophthalmic diseases including diabetes, age-related macular degeneration, retinal artery embolism, retinal vein occlusion, glaucoma and non-glaucomatous optic neuropathies. Increasingly, sophisticated imaging and analysis techniques have the potential to provide relevant clinical information regarding disease risk and progression; however, further studies are required to verify associations and strengthen the predictive power of these techniques. We summarize the current state of knowledge regarding retinal microvascular characteristics and eye disease.

The Treatment of Giant Cell Arteritis

OPINION STATEMENT

Giant cell arteritis (GCA) is a systemic inflammatory vasculitis affecting medium and large vessels with potentially sight and life-threatening complications. Early diagnosis and prompt treatment are imperative in order to prevent vision loss and progression of the disease. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are inflammatory markers which are elevated in the majority of patients and support the diagnosis of GCA among patients who present with typical symptoms. GCA is confirmed with superficial temporal artery biopsy which demonstrates characteristic pathological findings. Treatment of suspected ophthalmic involvement must be initiated urgently, even when diagnostic studies are pending. High dose corticosteroid therapy is the mainstay of treatment and is administered either intravenously or orally to prevent further vision loss and treat systemic vasculitis. Oral corticosteroid therapy is required for months to years with careful follow-up and periodic laboratory evaluations with ESR and CRP. Corticosteroids are tapered gradually over months and may be associated with complications such as hypertension, diabetes mellitus, osteoporosis, psychosis, peptic ulcer disease, and infection. Supplementation with calcium, vitamin D, bisphosphonate therapy, antimicrobial prophylaxis, and initiation of a proton pump inhibitor or Histamine H2-receptor antagonist should be considered. Recurrence of inflammation is common in GCA and necessitates an escalation of corticosteroid dose. Adjunctive immunomodulatory therapy may be considered in patients experiencing relapsing inflammation despite high doses of corticosteroids or those with corticosteroid-induced complications. Emerging evidence for adjunctive therapy with tocilizumab, methotrexate, aspirin, angiotensin receptor blockers, and statins is encouraging and may lead to a more mainstream role for these therapies among patients with GCA.

Acute vision loss and choroidal filling delay in the absence of giant-cell arteritis

Giant-cell arteritis (GCA) is a visually devastating disease that often progresses to severe bilateral vision loss if untreated. Diagnosis of GCA is made challenging by the protean nature of the disease and the lack of a simple test that is both highly sensitive and specific. Choroidal filling delay on fluorescein angiography (FA) has been touted as a highly characteristic feature of GCA-related vision loss, although knowledge of both the sensitivity and specificity of this finding remains unproven. We report our experience of delayed choroidal filling on FA in a series of seven patients referred to an academic neuro-ophthalmology practice due to concern for GCA. Despite the FA findings, our examination, diagnostic testing, and long-term follow-up excluded the diagnosis of GCA in all cases, suggesting that choroidal perfusion abnormalities may occur in the absence of GCA. When evaluating a patient for acute vision loss, the astute clinician must remain cognizant of the limitations of FA in the diagnosis of GCA.

New developments in giant cell arteritis

Giant cell arteritis (GCA) is a medium-to-large vessel vasculitis with potentially sight- and life- threatening complications. Our understanding of the pathogenesis, diagnosis, and treatment of GCA has advanced rapidly in recent times. The validity of using the American College of Rheumatology guidelines for diagnosis of GCA in a clinical setting has been robustly challenged. Erythrocyte sedimentation rate, an important marker of inflammation, is lowered by the use of statins and nonsteroidal anti-inflammatory drugs. Conversely, it may be falsely elevated with a low hematocrit. Despite the emergence of new diagnostic modalities, temporal artery biopsy remains the gold standard. Evidence suggests that shorter biopsy lengths and biopsies done weeks to months after initiation of steroid therapy are still useful. New imaging techniques such as positron emission tomography have shown that vascular inflammation in GCA is more widespread than originally thought. GCA, Takayasu arteritis, and polymyalgia rheumatica are no longer thought to exist as distinct entities and are more likely parts of a spectrum of disease. A range of immunosuppressive drugs have been used in conjunction with corticosteroids to treat GCA. In particular, interleukin-6 inhibitors are showing promise as a therapy.

[Optical coherence tomography angiography in glaucoma diagnosis]

According to literature data, vascular dysfunction may well contribute to the development of glaucomatous optic neuropathy, which makes it reasonable to search for new imaging techniques capable of early diagnosis and monitoring of glaucoma through assessment of retinal, optic nerve head (ONH), and choroidal perfusion. Optical coherence tomography angiography (OCTA), a recently introduced method based on the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm, enables evaluation of both retinal and choroidal blood flow in peripapillary and macular areas. The first studies involving OCTA have revealed a decrease in retinal blood flow in glaucoma. It has also been shown that visual field indices correlate better with the peripapillary flow index than with morphometric parameters of the optic nerve head (ONH) and peripapillary retina. OCT angiography has great potential for ONH blood flow assessment during physiological tests, which is an important step towards understanding pathogenesis of glaucoma.

Surgery for nonarteritic anterior ischemic optic neuropathy

BACKGROUND

Nonarteritic anterior ischemic optic neuropathy (NAION) is characterized by sudden and painless loss of vision in the eye, accompanied by pallid swelling of the optic disc. Its etiology is unknown and no medical therapy has been proven effective in treating this condition. Optic nerve decompression surgery, a proposed treatment for NAION, involves making two or more slits or a window in the tissue surrounding the optic nerve, thereby allowing cerebrospinal fluid to escape, and theoretically reducing the pressure surrounding the optic nerve.

OBJECTIVES

The objective of this review was to assess the safety and efficacy of surgery compared with other treatment or no treatment in people with NAION.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 10), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2014), EMBASE (January 1980 to October 2014), PubMed (1948 to October 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 23 October 2014.

SELECTION CRITERIA

All randomized trials of surgical treatment of NAION were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

From full-text copies of all reports from relevant trials, one author extracted data which were verified by another author. No data synthesis was required.

MAIN RESULTS

The one included trial, in which 258 participants were randomized, was stopped early for futility. At the time of the 24-month report the follow-up rate was 95.3% for six months and 67.4% for 24 months (174 participants; 89 careful follow-up and 85 surgery). There was no evidence of a benefit of surgery on visual acuity. Measurements of visual acuity and visual fields were performed by a technician masked to the treatment received. At six months 32.0% of the surgery group had improved visual acuity by 3 or more lines compared with 42.6% of the careful follow-up group (unadjusted risk ratio (RR) 0.75, 95% confidence interval (CI) 0.54 to 1.04). At 24 months 29.4% of the surgery group had improved compared with 31.0% of the careful follow-up group (unadjusted RR 0.95, 95% CI 0.60 to 1.49). Participants who underwent surgery more often lost 3 or more lines of visual acuity in the study eye, although the increased risk was not statistically significant. At six months 18.9% in the surgery group had worsened visual acuity in the study eye compared with 14.8% in the careful follow-up group (RR 1.28; 95% CI 0.73 to 2.24). At 24 months 20.0% in the surgery group had worsened visual acuity in the study eye compared with 21.8% in the careful follow-up group (RR 0.92; 95% CI 0.51 to 1.64). Participants who received surgery experienced both intraoperative and postoperative adverse events, including central retinal artery occlusion during surgery and light perception vision at six months (one participant); and immediate loss of light perception following surgery and loss of vision that persisted to the 12-month visit (two participants). In the careful follow-up group, two participants had no light perception at the six-month follow-up visit; one of these had improved to light perception at 12 months. Pain was the most common adverse event in the surgery group (17% in surgery group versus 3% in the careful follow-up group at one week). Diplopia (double vision) was the next most common complication (8% in the surgery group versus 1% in the careful follow-up group at one week); at three months there was no statistically significant difference in proportion of participants with diplopia between the two groups.

AUTHORS' CONCLUSIONS

The only eligible trial provided no evidence of a beneficial effect of optic nerve decompression surgery for NAION. Future research should focus on increasing our understanding of the etiology and prognosis of NAION. New treatment options should be examined in the context of randomized clinical trials.

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.

Intravitreal triamcinolone injections in non-arteritic anterior ischemic optic neuropathy

BACKGROUND

In non-arteritic anterior ischemic optic neuropathy (NA-AION), no treatments have demonstrated to be effective in recovering visual loss in randomized clinical trials. Oral steroids have been evaluated, and small series of intravitreal triamcinolone acetonide (IVTA) injection in NA-AION have been reported. The purpose of our study was to report the visual outcome and morphological changes in response to a single IVTA injection as a treatment for patients with NA-AION.

PATIENTS AND METHODS

The charts of 36 patients with visual symptoms and optic disc swelling caused by NA-AION were evaluated. Twenty-one patients had received 4 mg IVTA and were compared with 15 non-treated patients. Visual acuity (VA), retinal nerve fiber layer thickness and static visual field were evaluated after 6 months.

RESULTS

VA improvement at 6 months is statistically better in the treated group than in the non-treated group (p = 0.0035). In the treated group, there was a significant inverse correlation between the delay of the injection and the visual acuity achieved at 6 months (p < 0.0083**, r = -0.56). A significant improvement of the visual field was noted in the injected group when compared with the non-treated group at 6 months (p < 0.0028).

DISCUSSION

In this retrospective study, patients receiving IVTA in the acute phase of NA-AION have better improvement of VA and visual field during the follow-up period of 6 months. However, only a large randomized controlled trial may enable to evaluate the benefits of IVTA Injections on visual outcome in NA-AION.

Bilateral Simultaneous Nonarteritic Anterior Ischaemic Optic Neuropathy: Case Report

Bilateral simultaneous nonarteritic anterior ischaemic optic neuropathy (NAION) is extremely rare. A 57-year-old woman presented with bilateral optic disc oedema and peripapillary splinter haemorrhages. Initial visual acuities were hand movements in the right eye and light perception in the left eye. The patient had a mildly elevated diastolic blood pressure and glucose intolerance. Erythrocyte sedimentation rate and C-reactive protein levels were within normal limits. Temporal artery biopsy was negative for temporal arteritis. Marked visual improvement occurred in both eyes (0.8 in the right eye, 0.6 in the left eye) after systemic steroid therapy in the 16th month of follow-up.

Optical coherence tomography study of experimental anterior ischemic optic neuropathy and histologic confirmation

PURPOSE

The optic nerve is part of the central nervous system, and interruption of this pathway due to ischemia typically results in optic atrophy and loss of retinal ganglion cells. In this study, we assessed in vivo retinal changes following murine anterior ischemic optic neuropathy (AION) by using spectral-domain optical coherence tomography (SD-OCT) and compared these anatomic measurements to that of histology.

METHODS

We induced ischemia at the optic disc via laser-activated photochemical thrombosis, performed serial SD-OCT and manual segmentation of the retinal layers to measure the ganglion cell complex (GCC) and total retinal thickness, and correlated these measurements with that of histology.

RESULTS

There was impaired perfusion and leakage at the optic disc on fluorescein angiography immediately after AION and severe swelling and distortion of the peripapillary retina on day-1. We used SD-OCT to quantify the changes in retinal thickness following experimental AION, which revealed significant thickening of the GCC on day-1 after ischemia followed by gradual thinning that plateaued by week-3. Thickness of the peripapillary sensory retina was also increased on day-1 and thinned chronically. This pattern of acute retinal swelling and chronic thinning on SD-OCT correlated well with changes seen in histology and corresponded to loss of retinal ganglion layer cells after ischemia.

CONCLUSIONS

This was a serial SD-OCT quantification of acute and chronic changes following experimental AION, which revealed changes in the GCC similar to that of human AION, but over a time frame of weeks rather than months.

Ischemic optic neuropathies - where are we now?

Ischemic optic neuropathy is of two types: anterior and posterior. Non-arteritic anterior ischemic optic neuropathy (NA-AION) is the most common type of ischemic optic neuropathy. There are three major misconceptions about NA-AION: (1) that its pathogenesis is not known, (2) that NA-AION and ischemic cerebral stroke are similar in nature, pathogenetically and in management, and (3) that there is no treatment. All these misconceptions are based on lack of in-depth knowledge of the subject. They are discussed in the light of our current scientific knowledge. The pathogenesis of NA-AION is known but is highly complex. NA-AION and ischemic cerebral stroke are very different clinical entities, pathogenetically and in management. Aspirin has no beneficial effect. Corticosteroid therapy during the initial stages can be beneficial. To reduce the risk of development of NA-AION in the other eye or of further visual loss in the same eye, it is essential to reduce as many risk factors as possible. Management of arteritic anterior ischemic optic neuropathy and of posterior ischemic optic neuropathy is discussed.

Optic neuritis, its differential diagnosis and management

The aim of this review is to summarize the latest information about optic neuritis, its differential diagnosis and management. Optic Neuritis (ON) is defined as inflammation of the optic nerve, which is mostly idiopathic. However it can be associated with variable causes (demyelinating lesions, autoimmune disorders, infectious and inflammatory conditions). Out of these, multiple sclerosis (MS) is the most common cause of demyelinating ON. ON occurs due to inflammatory processes which lead to activation of T-cells that can cross the blood brain barrier and cause hypersensitivity reaction to neuronal structures. For unknown reasons, ON mostly occurs in adult women and people who live in high latitude. The clinical diagnosis of ON consists of the classic triad of visual loss, periocular pain and dyschromatopsia which requires careful ophthalmic, neurologic and systemic examinations to distinguish between typical and atypical ON. ON in neuromyelitis optica (NMO) is initially misdiagnosed as ON in MS or other conditions such as Anterior Ischemic Optic Neuropathy (AION) and Leber’s disease. Therefore, differential diagnosis is necessary to make a proper treatment plan. According to Optic Neuritis Treatment Trial (ONTT) the first line of treatment is intravenous methylprednisolone with faster recovery and less chance of recurrence of ON and conversion to MS. However oral prednisolone alone is contraindicated due to increased risk of a second episode. Controlled High-Risk Subjects Avonex^® Multiple Sclerosis Prevention Study “CHAMPS”, Betaferon in Newly Emerging Multiple Sclerosis for Initial Treatment “BENEFIT” and Early Treatment of MS study “ETOMS” have reported that treatment with interferon β-1a,b results in reduced risk of MS and MRI characteristics of ON. Contrast sensitivity, color vision and visual field are the parameters which remain impaired mostly even after good recovery of visual acuity.

Surgery for nonarteritic anterior ischemic optic neuropathy

BACKGROUND

Nonarteritic ischemic optic neuropathy (NAION) is characterized by sudden and painless loss of vision in the eye, accompanied by pallid swelling of the optic disc. Its etiology is unknown and no medical therapy has been proven effective in treating this condition. Optic nerve decompression surgery, a proposed treatment for NAION, involves making two or more slits or a window in the tissue surrounding the optic nerve, thereby allowing cerebrospinal fluid to escape, and theoretically reducing the pressure surrounding the optic nerve.

OBJECTIVES

The objective of this review was to assess the safety and efficacy of surgery compared with other treatment or no treatment in people with nonarteritic ischemic optic neuropathy.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 11), MEDLINE (January 1950 to November 2011), EMBASE (January 1980 to November 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (http://clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 19 November 2011.

SELECTION CRITERIA

All randomized trials of surgical treatment of NAION were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

We obtained full copies of all potentially relevant articles. One author extracted data which was verified by another author. No data synthesis was required.

MAIN RESULTS

The one included trial randomized 258 participants and was stopped early for futility. At the time of the 24-month report the follow-up rate was 95.3% for six months and 67.4% for 24 months (174 participants; 89 careful follow up and 85 surgery). There was no evidence of a benefit of surgery on visual acuity. Measurements of visual acuity and visual fields were performed by a technician masked to the treatment received. At six months 32.0% of the surgery group had improved visual acuity by three or more lines compared with 42.6% of the careful follow up group (unadjusted relative risk (RR) 0.75, 95% confidence interval (CI) 0.54 to 1.04). At 24 months 29.4% of the surgery group had improved compared with 31.0% of the careful follow up group (unadjusted RR 0.95, 95% CI 0.60 to 1.49). Participants who underwent surgery had a greater risk of losing three or more lines of vision, although the increased risk was not statistically significant. At six months 18.9% in the surgery group had worsened compared with 14.8% in the careful follow up group (RR 1.28; 95% CI 0.73 to 2.24). At 24 months 20.0% in the surgery group had worsened compared with 21.8% in the careful follow up group (RR 0.92; 95% CI 0.51 to 1.64). Participants who received surgery experienced both intraoperative and postoperative adverse events, including central retinal artery occlusion during surgery and light perception vision at six months (one participant); and immediate loss of light perception following surgery and loss of vision that persisted to the 12-month visit (two participants). In the careful follow-up group, two participants had no light perception at the six-month follow-up visit; one of these had improved to light perception at 12 months. Pain was the most common adverse event in the surgery group (17% in surgery group versus 3% in the careful follow-up group at one week). Diplopia (double-vision) was the next most common complication (8% in the surgery group versus 1% in the careful follow-up group at one week); at three months there was no statistically significant difference in proportion of participants with diplopia between the two groups.

AUTHORS' CONCLUSIONS

Results from the single trial indicate no evidence of a beneficial effect of optic nerve decompression surgery for NAION. Future research should focus on increasing our understanding of the etiology and prognosis of NAION. New treatment options should be examined in the context of randomized clinical trials.

Management of ischemic optic neuropathies

Ischemic optic neuropathies (IONs) consist primarily of two types: anterior ischemic optic neuropathy (AION) and posterior ischemic optic neuropathy (PION). AION comprises arteritic AION (A-AION: due to giant cell arteritis) and non-arteritic AION (NA-AION: due to other causes). PION consists of arteritic PION (A-PION: due to giant cell arteritis), non-arteritic PION (NA-PION: due to other causes), and surgical PION (a complication of several systemic surgical procedures). These five types of ION are distinct clinical entities etiologically, pathogenetically, clinically and from the management point of view. In the management of AION, the first crucial step with patients aged 50 and over is to identify immediately whether it is arteritic or not because A-AION is an ophthalmic emergency and requires urgent treatment with high-dose steroid therapy to prevent any further visual loss in one or both eyes. Patients with NA-AION, when treated with systemic corticosteroid therapy within first 2 weeks of onset, had significantly better visual outcome than untreated ones. Systemic risk factors, particularly nocturnal arterial hypotension, play major roles in the development of NA-AION; management of them is essential in its prevention and management. NA-PION patients, when treated with high-dose systemic steroid therapy during the very early stages of the disease, showed significant improvement in visual acuity and visual fields, compared to untreated eyes. A-PION, like A-AION, requires urgent treatment with high-dose steroid therapy to prevent any further visual loss in one or both eyes. There is no satisfactory treatment for surgical PION, except to take prophylactic measures to prevent its development.

Acute retinal arterial occlusive disorders

The initial section deals with basic sciences; among the various topics briefly discussed are the anatomical features of ophthalmic, central retinal and cilioretinal arteries which may play a role in acute retinal arterial ischemic disorders. Crucial information required in the management of central retinal artery occlusion (CRAO) is the length of time the retina can survive following that. An experimental study shows that CRAO for 97min produces no detectable permanent retinal damage but there is a progressive ischemic damage thereafter, and by 4h the retina has suffered irreversible damage. In the clinical section, I discuss at length various controversies on acute retinal arterial ischemic disorders. Classification of acute retinal arterial ischemic disorders: These are of 4 types: CRAO, branch retinal artery occlusion (BRAO), cotton wool spots and amaurosis fugax. Both CRAO and BRAO further comprise multiple clinical entities. Contrary to the universal belief, pathogenetically, clinically and for management, CRAO is not one clinical entity but 4 distinct clinical entities - non-arteritic CRAO, non-arteritic CRAO with cilioretinal artery sparing, arteritic CRAO associated with giant cell arteritis (GCA) and transient non-arteritic CRAO. Similarly, BRAO comprises permanent BRAO, transient BRAO and cilioretinal artery occlusion (CLRAO), and the latter further consists of 3 distinct clinical entities - non-arteritic CLRAO alone, non-arteritic CLRAO associated with central retinal vein occlusion and arteritic CLRAO associated with GCA. Understanding these classifications is essential to comprehend fully various aspects of these disorders. Central retinal artery occlusion: The pathogeneses, clinical features and management of the various types of CRAO are discussed in detail. Contrary to the prevalent belief, spontaneous improvement in both visual acuity and visual fields does occur, mainly during the first 7 days. The incidence of spontaneous visual acuity improvement during the first 7 days differs significantly (p<0.001) among the 4 types of CRAO; among them, in eyes with initial visual acuity of counting finger or worse, visual acuity improved, remained stable or deteriorated in non-arteritic CRAO in 22%, 66% and 12% respectively; in non-arteritic CRAO with cilioretinal artery sparing in 67%, 33% and none respectively; and in transient non-arteritic CRAO in 82%, 18% and none respectively. Arteritic CRAO shows no change. Recent studies have shown that administration of local intra-arterial thrombolytic agent not only has no beneficial effect but also can be harmful. Prevalent multiple misconceptions on CRAO are discussed. Branch retinal artery occlusion: Pathogeneses, clinical features and management of various types of BRAO are discussed at length. The natural history of visual acuity outcome shows a final visual acuity of 20/40 or better in 89% of permanent BRAO cases, 100% of transient BRAO and 100% of non-arteritic CLRAO alone. Cotton wools spots: These are common, non-specific acute focal retinal ischemic lesions, seen in many retinopathies. Their pathogenesis and clinical features are discussed in detail. Amaurosis fugax: Its pathogenesis, clinical features and management are described.

Krogh cylinders in retinal development, panretinal hypoperfusion and diabetic retinopathy

The volume of cells that a length of capillary supplies with O(2) is called a Krogh cylinder. This geometric 'tissue unit' was named after the Danish zoophysiologist and Nobel laureate August Krogh who made important discoveries in the fields of external and internal respiration in the first half of the last century. Krogh's ideas concerning tissue O(2) distribution can be extrapolated to retinal oxygenation by larger vessels (including arterioles, arteries and even veins) and by vessel groups within higher-order 'microvascular units' (including the choroid). During retinal development, for example, the difference in pO(2) levels within arteries and capillaries determines Krogh cylinders of different radius and establishes the periarterial capillary-free zone of His. The O(2) supply to the venous end of a tissue unit may be compromised during periods of reduced perfusion, increased O(2) consumption or hypoxaemia, resulting in an 'anoxic corner' of the Krogh cylinder. A funnel of hypometabolic (and therefore hypoxia-tolerant) cells will likely intervene between the necrotic cells and unaffected cells located closer to the O(2) source. Macular perivenular whitening heralds anoxic corners and/or hypoxic funnels owing to hypoperfusion within second-order microvascular units. In eyes with extensive retinal capillary closure from diabetes, Krogh cylinders surround the medium-sized arteries and veins that form arteriovenous shunts while traversing the midperipheral retina. These isolated tissue units incorporate an outer sheath of hypoxic cells within which vascular endothelial growth factor is upregulated. This 'angiogenic sheath' expands following retinal detachment; it corresponds to the hypoxia-tolerant funnel within capillary-based tissue units and to the cerebral penumbra after stroke.

Ophthalmologic manifestations commonly misdiagnosed as demyelinating events in multiple sclerosis patients

PURPOSE OF REVIEW

Multiple sclerosis may affect both afferent and efferent visual pathways, and sometimes physicians err on ordinary ophthalmologic diagnosis due to overlapping symptoms between demyelinating and nondemyelinating visual diseases. The present article highlights nondemyelinating ocular occurrences due to physiologic or other pathologic processes that may appear in some patients.

RECENT FINDINGS

Optic neuritis is representative of the most common and best-studied demyelinating visual occurrence in multiple sclerosis. However, other nondemyelinating visual disturbances also seen in the general population may be erroneously interpreted as being part of the underlying disease. This comparison has not been documented and may be helpful to overcome such difficulties.

SUMMARY

Based on clinical history and some strategies of ophthalmologic examination, physicians can achieve the correct diagnosis. Some clinical situations, however, may be challenging and a multidisciplinary approach in the care of multiple sclerosis is warranted.