Differentiation of compressive from glaucomatous optic neuropathy with spectral-domain optical coherence tomography

Surgical management of arterial compression of the anterior visual pathway - a systematic review

INTRODUCTION

Visual loss secondary to a vascular loop or atherosclerotic carotid has been a controversial topic for many years with contemporary data supporting its existence. The role of surgery in the management of this entity is not well defined. We performed a systematic review describing the different surgical techniques and outcomes.

METHOD

A search strategy was devised in accordance with the 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. An electronic search was performed from the databases Pubmed, Google scholar, Scopus and Web of Science databases. The search was performed from inception until the 10th of December 2023.

RESULTS

A total of 2469 articles were screened with 15 articles describing 18 patients being included. Of these cases, eleven involved compression due to unilateral or bilateral dolichoectatic internal carotid artery (ICA), three for a dolichoectatic anterior cerebral artery (ACA), two for a combination of a dolichoectatic ICA with a dorsolateral ophthalmic artery and two for a combination of a dolichoectatic ICA and ACA.

CONCLUSION

Two distinct compressive entities can be differentiated. Compressive optic neuropathy at the entrance of the optic canal due to pinching between an ectatic carotid and the falciform ligament. A second entity is due to compression of the cisternal optic nerve or chiasm secondary tot a vascular loop. A variety of surgical techniques have been described and include: unroofing of the optic canal with sectioning of the falciform ligament; microvascular decompression with a Teflon® pellet, a muscle patch or, rerouting of the offending vessel with a sling. Larger and prospective studies are needed to better define the role of surgery in this, probably, underreported pathology.

Utility of ganglion cells for the evaluation of anterior visual pathway pathology: a review

The management of optic neuropathy is fundamental to neuro-ophthalmic practice. Following the invention of the ophthalmoscope, clinicians, for a century or more, relied upon fundus examination in the evaluation of optic neuropathy. However, the advent of optical coherence tomography, based on the principle of backscattering of light and interferometry, has revolutionized the analysis of optic nerve and retinal disorders. Optical coherence tomography has proven of particular value in the measurement, at the micron level, of the peripapillary retinal nerve fibre layer and the ganglion cell layer. These measurements have proven critical in the differential diagnosis and monitoring of optic neuropathy. Specifically, thinning of the peripapillary nerve fibre layer provides evidence of axonal loss affecting any sector of the optic nerve. Thinning of the macular ganglion cell layer, on the other hand, shows a more precise correlation with visual deficits due to retrograde degeneration following optic nerve damage, although limited to central retina. In daily practise, optical coherence tomography is of great value in assessing the diagnosis, prognosis and response to treatment in optic neuropathy. Particular advances have been made, for example, in the assessment of optic neuritis, papilloedema and chiasmal compression which have translated to everyday practice. As with any other imaging technology the clinician must have a clear understanding of acquisition artefacts. A further issue is the relatively limited normative database in sub-populations such as the young and individuals with a refractive error > + 5 or < -5 dioptres.

Normal-Tension Glaucoma Complicated by a Giant Internal Carotid-Ophthalmic Artery Aneurysm

Purpose. We describe a patient with normal tension glaucoma (NTG) of several years whose management was complicated by the presence of a giant internal carotid-ophthalmic artery aneurysm. Observations. A 72-year-old woman presented to our glaucoma clinic with accelerated deterioration of her vision in her left eye (OS) over a 1-month period. Her ophthalmic history was most notable for bilateral NTG diagnosed 3 years prior which had been treated with several laser trabeculoplasty OS and topical bimatoprost 0.01% eye drops in both eyes (OU). Upon evaluation, her visual acuity OS had worsened, and visual field (VF) testing showed extensive progressive losses temporally and pericentrally OS over a year with stable IOP measurements and no neurological complaints. Given her atypical NTG progression, she was referred for an urgent neurological evaluation which revealed an unruptured giant left internal carotid-ophthalmic aneurysm. Following the successful treatment of the aneurysm with platinum coils, she continued to demonstrate additional bilateral ophthalmic changes including further progression of VF loss and RNFL thinning OS > OD on follow-up. Conclusion and Importance. Overall, this report describes a unique complication in the management of a patient with chronic bilateral NTG in the form of a giant internal carotid-ophthalmic aneurysm. Moreover, it highlights the need for clinicians to maintain a degree of suspicion for compressive lesions of the optic nerve when presented with atypical progression of VFs and/or visual acuity loss in glaucomatous patients.

Longitudinal changes in optic disc cupping from the baseline in chiasmal lesion optic neuropathy and glaucoma

We aimed to investigate the changes in cupping in chiasmal lesion optic neuropathy (chON) compared to baseline optic disc and glaucoma. We used a novel study design to enroll patients who had fundus photographs incidentally taken during routine health check-ups prior to the onset of optic neuropathy. In 31 eyes (21 patients) with chON and 33 eyes (30 patients) with glaucoma, we investigated the change in cup-to-disc (C/D) area from the baseline to overt cupping using flicker analysis. Compared to the baseline, 23 eyes (74.2%) had increased cup size and 3 (9.7%) had vascular configuration changes in the chONgroup; in contrast, all glaucoma eyes exhibited changes in cup size and vascular configuration. The increase in C/D area ratio was significantly smaller in chON (0.04 ± 0.04) compared to glaucoma (0.10 ± 0.04, P < 0.001); the minimum residual neuroretinal rim width showed a more pronounced difference (29.7 ± 8.2% vs 7.1 ± 3.9%, P < 0.001). The changes distributed predominantly towards the nasal direction in chON, contrasting the changes to the arcuate fibers in glaucoma. In conclusion, our results provide the first longitudinal evidence of true pathological cupping in chONcompared to photographically disease-free baseline. The marked difference in the residual minimum rim width reaffirms the importance of rim obliteration in the differential diagnosis between the two diseases.

Virtual reality headsets for perimetry testing: a systematic review

Standard automated perimetery is considered the gold standard for evaluating a patient's visual field. However, it is costly and requires a fixed testing environment. In response, perimetric devices using virtual reality (VR) headsets have emerged as an alternative way to measure visual fields in patients. This systematic review aims to characterize both novel and established VR headsets in the literature and explore their potential applications within visual field testing. A search was conducted using MEDLINE, Embase, CINAHL, and the Core Collection (Web of Science) for articles published until January 2023. Subject headings and keywords related to virtual reality and visual field were used to identify studies specific to this topic. Records were first screened by title/abstract and then by full text using predefined criteria. Data was extracted accordingly. A total of 2404 records were identified from the databases. After deduplication and the two levels of screening, 64 studies describing 36 VR headset perimetry devices were selected for extraction. These devices encompassed various visual field measurement techniques, including static and kinetic perimetry, with some offering vision rehabilitation capabilities. This review reveals a growing consensus that VR headset perimetry devices perform comparably to, or even better than, standard automated perimetry. They are better tolerated by patients in terms of gaze fixation, more cost-effective, and generally more accessible for patients with limited mobility.

Topographic comparison of the retinal microvascular changes between patients with compressive and glaucomatous optic neuropathies

We investigated the difference in optical coherence tomography angiography characteristics between the patients with compressive optic neuropathy (CON, n = 26) and glaucomatous optic neuropathy (GON, n = 26), who were matched for the severity of visual field defect. The peripapillary retinal nerve fiber layer (pRNFL) thickness in the nasal and temporal sectors was thinner in the CON group, whereas the inferior pRNFL thickness was thinner in the GON group. Accordingly, the CON group had lower peripapillary vessel density (pVD) in the nasal and temporal sectors, and the GON group in the inferior sector. In the macular area, the CON group had a thinner macular ganglion cell-inner plexiform layer in the superior and nasal sectors, whereas the GON group in the inferior sector. However, the CON group did not have a lower macular VD than the GON group in any sector, whereas the GON group exhibited lower superficial capillary plexus VD in the superior, inferior, and temporal sectors. Comparison of the structure-vasculature correlation revealed a significant difference in the nasal and temporal peripapillary areas and superior and nasal macular sectors; a decrease in VD was greater in the GON group than in the CON group when the comparable structural change occurred.

Comparison of the retinal microvasculature between compressive and glaucomatous optic neuropathy

PURPOSE

To compare the patterns of retinal microvasculature change in the peripapillary and macular region between compressive optic neuropathy (CON) and glaucomatous optic neuropathy (GON), and to assess the ability of optical coherence tomography angiography (OCTA) in differentiating the two conditions.

METHODS

This cross-sectional study included 108 participants (108 eyes), 36 with CON, 36 with GON, and 36 healthy controls. The CON and GON eyes were matched by the average peripapillary retinal nerve fiber layer (pRNFL) thickness (1:1). Optical coherence tomography (OCT) and OCTA were performed to compare the structural and vascular change of the peripapillary and macular region between groups.

RESULTS

Both CON and GON eyes showed more severe structural and vascular damage than the control eyes. The CON eyes had lower pRNFL thickness than the GON eyes in the temporal and nasal quadrants, and thicker pRNFL thickness in the inferior quadrant. The average GCC thickness did not differ between the two groups. The peripapillary vessel density of the CON group was significantly higher in the inferior sectors than that of the GON group. In the macular region, the CON group had significantly higher vessel density in the whole image, the temporal sector in parafovea region, and the temporal, superior, and inferior sectors in perifovea region.

CONCLUSION

To a similar degree of structural damage, CON had less retinal vascular impairment than GON, especially in the macular region, and the significance of the finding needs further evaluation.

Discrimination of glaucomatous from non-glaucomatous optic neuropathy with swept-source optical coherence tomography

OBJECTIVE

To assess the ability of optic nerve head (ONH) parameters, peripapillary retinal nerve fiber layer (pRNFL), and macular ganglion cell layer (GCL) thickness measurements with swept-source optical coherence tomography (SS-OCT), to discriminate between glaucomatous and non-glaucomatous optic neuropathy (GON and NGON).

METHODS

This retrospective cross-sectional study involved 189 eyes of 189 patients, 133 with GON and 56 with NGON. The NGON group included ischemic optic neuropathy, previous optic neuritis, and compressive, toxic-nutritional, and traumatic optic neuropathy. Bivariate analyses of SS-OCT pRNFL and GCL thickness and ONH parameters were performed. Multivariable logistic regression analysis was employed to obtain predictor variables from OCT values, and the area under the receiver operating characteristic curve (AUROC) was calculated to differentiate between NGON and GON.

RESULTS

Bivariate analyses showed that the overall and inferior quadrant of the pNRFL was thinner in the GON group (P=0.044 and P<0.01), while patients with NGON had thinner temporal quadrants (P=0.044). Significant differences between the GON and NGON groups were identified in almost all the ONH topographic parameters. Patients with NGON had thinner superior GCL (P=0.015), but there were no significant differences in GCL overall and inferior thickness. Multivariate logistic regression analysis demonstrated that vertical cup-to-disc ratio (CDR), cup volume, and superior GCL provided independent predictive value for differentiating GON from NGON. The predictive model of these variables along with disc area and age achieved an AUROC=0.944 (95% CI 0.898-0.991).

CONCLUSIONS

SS-OCT is useful in discriminating GON from NGON. Vertical CDR, cup volume, and superior GCL thickness show the highest predictive value.

Optical Coherence Tomography Angiography for the Differentiation of Glaucoma from Pituitary Macroadenoma Related Optic Disc Measurements

OBJECTIVE

To determine the potential of optical coherence tomography (OCT) and OCT angiography (OCTA) to distinguish between glaucoma and pituitary macroadenoma by optic disc appearance.

METHODS

This prospective case-control study comprised 31 patients: 23 with glaucoma (18 male, 5 female) and 8 with pituitary macroadenoma and chiasmatic compression (3 male, 5 female). The corresponding mean ages were 72.8 years (range 58-90) and 60.7 years (range 43-73). All participants underwent complete ophthalmological examination, spectral domain OCT and OCTA, and visual field testing. Clinical, imaging, and visual field results were compared between the groups.

RESULTS

On OCT analysis, the glaucoma group had relatively lower peripapillary retinal nerve fiber layer (RNFL) thickness (65.79 ± 15.46, 86.0 ± 11.37, respectively, P = .002) and lower rim area (1.00 ± 0.22 mm2 and 1.2 ± 0.15 mm2, respectively, P = .005). On OCTA, peripapillary vessel density was significantly lower in all quadrants in the glaucoma group. The significance of these between-group differences was maintained when patients were stratified by visual field mean deviation.

CONCLUSIONS

This is the first comparative analysis of optic disc morphology between glaucoma and pituitary macroadenoma using combined OCT and OCTA. The results yielded lower peripapillary RNFL thickness, lower rim area, and lower peripapillary vessel density in the glaucoma group. These parameters may aid in the initial differentiation between these two optic neuropathies.

Dolichoectatic arterial compression of the chiasm and optic nerve: a case report

Dolichoectatic arterial compression of the anterior visual pathway is a rare but recognized condition. The functional impact, however, is still less clear. We describe a case of a 56-year-old male with diminished visual acuity in the left eye and incongruent inferior visual defect in both eyes caused by dolichoectasia due to a congenital hypoplasia of one horizontal segment of the circle of Willis and subsequent arterial compression of the chiasm and left optic nerve.

Peripapillary Vascular Density in Compressive Optic Neuropathy and Normal-Tension Glaucoma: A Severity-Controlled Comparison

Purpose

To investigate the differences in peripapillary vessel density (VD) between compressive optic neuropathy (CON) and normal-tension glaucoma (NTG).

Methods

We compared patients with chronic CON and NTG, particularly after strictly controlling the mean extent of macular damage by the area of the ganglion cell-inner plexiform layer (GCIPL) loss in optical coherence tomography (OCT). We compared retinal nerve fiber layer (RNFL) and GCIPL thickness from OCT and peripapillary and macular VD from OCT angiography (OCTA) between the CON and NTG groups.

Results

From the initial 184 patients with CON and 443 patients with OAG, we included 41 patients with CON (57 eyes) and 64 patients with NTG (75 eyes) with a comparable extent of macular GCIPL thinning. Under similar mean macular involvement, the peripapillary VD was significantly lower in the CON group than in the NTG group after considering the effects of age, spherical equivalent, visual field sensitivity, peripapillary RNFL (pRNFL) thickness, GCIPL thickness, and image quality scores (P < 0.001). Marked loss of VD in the temporal and nasal sectors in CON was notable, attributing to the significantly lower peripapillary VD compared to NTG.

Conclusions

Patients with CON had a significantly lower peripapillary VD than those with NTG under similar mean degrees of pRNFL thickness and GCIPL damage. Our results reveal the potential utility of OCTA VD besides OCT pRNFL thickness, in relation to different topographic patterns of pRNFL loss, and possible differences in the pathogenesis of microvascular compromise between CON and NTG.

Differences in optic nerve head structure between acute angle-closure glaucoma and open-angle glaucoma

This study aimed to compare the optic nerve head (ONH) structure in acute angle-closure glaucoma (AACG) and open-angle glaucoma (OAG) to investigate the differences in glaucomatous damage. The AACG and OAG eyes were matched with regard to global retinal nerve fiber layer thickness (RNFLT). AACG eyes were divided into two subgroups based on the presence of ONH swelling at the onset of AACG. RNFLT, Bruch's membrane opening-minimum rim width (BMO-MRW), and Bruch's membrane opening-minimum rim area (BMO-MRA) were analyzed. Global RNFLT values were similar in AACG and OAG groups, but lower than in the healthy group (P < 0.001). The global BMO-MRW and total BMO-MRA were significantly higher in AACG than in OAG group (P < 0.001, respectively). AACG showed similar global BMO-MRW and total BMO-MRA, irrespective of the presence or absence of ONH swelling, while AACG with ONH swelling was associated with significantly thinner global RNFLT compared to AACG without ONH swelling (P < 0.006). The result of differences in ONH structure between the OAG and AACG, especially the AACG with ONH swelling at the onset of AACG, suggests that the mechanisms of optic nerve damage in the two diseases are different.

Discriminating Between Compressive Optic Neuropathy With Glaucoma-Like Cupping and Glaucomatous Optic Neuropathy Using OCT and OCTA

Purpose

To discriminate between compressive optic neuropathy with glaucoma-like cupping (GL-CON) and glaucomatous optic neuropathy (GON) by comparing the peripapillary retinal nerve fiber layer (pRNFL) thickness and retinal microvasculature using optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA).

Methods

In this retrospective cross-sectional study, OCT scans were performed on 28 eyes of GL-CON, 34 eyes of GON, and 41control eyes to determine the pRNFL thickness, ganglion cell complex thickness, and cup/disc ratio. OCTA scans were conducted for 12 eyes of GL-CON, 15 eyes of GON, and 15 control eyes to measure the vessel density of the peripapillary and macular areas. Analysis of covariance was used to perform the comparisons, and the area under the curve was calculated.

Results

The GON eyes had a significantly thinner pRNFL in the inferior quadrant and greater vertical cup/disc ratio than the GL-CON eyes. In the radial peripapillary capillary segment, the vessel density of the GON in the inferior sectors was significantly lower than in the GL-CON. The superficial macular vessel density in the whole-image, peritemporal, perinasal, and peri-inferior sectors was significantly smaller in the GON group than in the GL-CON group. The best parameter for discriminating between GL-CON and GON was the superficial macular vessel density in the peritemporal sector.

Conclusions

GL-CON eyes showed a characteristic pattern of pRNFL and retinal microvascular changes.

Translational Relevance

GL-CON can be effectively distinguished from GON by detecting the alterations in the pRNFL and retinal microvasculature using OCT and OCTA.

Automated macular segmentation can distinguish glaucomatous from compressive optic neuropathy

PURPOSE

To compare macular damage in glaucomatous optic neuropathy (GON) and compressive optic neuropathy (CON) and assess its diagnostic accuracy in distinguishing between diseases.

METHODS

Observational, cross-sectional, single-center study. Patients with GON, CON, and healthy controls were included according to the eligibility criteria. An automated spectral-domain optical coherence tomography (SD-OCT) algorithm was used to segment the circumpapilary retinal nerve fiber layer (cpRNFL) and macula. The layer thickness was measured in each sector according to the Early Treatment Diabetic Retinopathy Study and the 6-sector Garway-Heath-based grids. Data was compared across all study groups, and the significance level was set at 0.05.

RESULTS

Seventy-five eyes of 75 participants, 25 with GON, 25 with CON, and 25 healthy controls (CG), were included. Macular thickness was diminished in the ganglion cell complex of GON and CON patients compared to CG (p<0.05). The best Garway-Heath-based grid parameters for distinguishing GON and CON were the nasal-inferior (NI) and nasal-superior sectors and the NI/temporal inferior (TI) damage ratios in the macular ganglion cell (mGCL) and inner plexiform (IPL) layers. Moreover, the combination of the NI sector and NI/TI damage ratios in both layers had higher discriminative power (AUC 0.909; 95% CI 0.830-0.988; p<0.001) than combining parameters in each layer separately.

CONCLUSION

Our findings suggest that the evaluation of macular segmented layers damage by SD-OCT may be a helpful add-on tool in the differential diagnosis between GON and CON.

The ICD-10 Glaucoma Severity Score Underestimates the Extent of Glaucomatous Optic Nerve Damage

PURPOSE

To evaluate the International Classification of Disease, Tenth Revision (ICD-10) codes used for glaucoma severity classification, which are based on the location of visual field (VF) defects; given the known poor sensitivity of the 24-2 visual field test to early disease and macular damage, we hypothesized that the ICD-10 codes would not accurately reflect the extent of glaucomatous damage.

DESIGN

Retrospective validity and reliability analysis.

METHODS

We evaluated 80 eyes with glaucomatous optic neuropathy (GON). Masked reviewers assigned an ICD-10 severity grade based on 24-2 VF. Two additional masked examiners determined the presence of optical coherence tomography (OCT) structural damage in each hemifield and/or central 5 degrees to define an OCT-based equivalent ICD-10 classification.

RESULTS

A total of 80 eyes with GON were classified as mild, moderate and advanced in 15, 23, and 42 cases, respectively, based on the 24-2 VF, and in 6, 7, and 67 cases, respectively, based on OCT. The OCT classifications were more severe in 29 of 80 cases (36%). In 33 cases (41.3%), macular damage detected by OCT was missed by the 24-2. In 4 of 80 cases (5%), the VF overestimated the severity, likely due to variability of the 24-2 test.

CONCLUSIONS

The ICD-10 system relies solely on damage seen on the 24-2 and as provides a 24-2 functional score rather than a "glaucoma" severity score. OCT revealed wide variation of damage across grades, with a significant proportion of the eyes showing macular structural damage missed with the 24-2 VF. Adding OCT information to the ICD-10 system would help it to more accurately reflect the extent of glaucomatous damage.

Structural and functional differentiation between compressive and glaucomatous optic neuropathy

Clinical diagnoses of slow, progressive, painless visual losses with various degrees of visual field (VF) losses and disc atrophy are often confused between suprasellar compressive optic neuropathy (CON) and open-angle glaucomatous optic neuropathy (GON). We plotted the thickness of the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) against the mean deviation (MD) of the VF of 34 eyes of CON at diagnosis, 30 eyes of CON after therapy, 29 eyes of GON, and 60 eyes of healthy controls in a cross-sectional investigation. At diagnosis, a disproportionally early pattern of structural thinning compared with the corresponding VF losses was unique to CON. GON- and CON-specific thinning parameters were generally useful in differentiating GON and CON from moderate to severe MD losses, but early MD losses (0 to - 6 dB) overlapped with GON in a CON-stage specific manner. GON-specific thinning parameters, RNFL in the inferior sector, and inferior to temporal macular GCIPL ratio showed overlap with posttreatment CON in the early MD losses with AUCs of 0.916 (95% CI 0.860-0.971; P < 0.001) and 0.890 (95% CI 0.811-0.968; P < 0.001), respectively. In comparison, CON-specific thinning parameters, superonasal, and inferonasal GCIPL showed overlap with CON at diagnosis for early MD losses. Overall, the nasal-to-temporal macular GCIPL ratio showed good discrimination between CON and GON throughout the MD range, with an AUC of 0.923 (95% CI 0.870-0.976; P < 0.001). Comparing GON with all stages of CON, the cut-point of 0.95 showed the lower nasal-to-temporal GCIPL ratio had a sensitivity of 72% and specificity of 90% for CON. However, the cut-point of 1.10 showed the superior-to-inferior GCIPL ratio had a sensitivity of 60% and specificity of 98% for GON.

Detecting glaucoma with only OCT: Implications for the clinic, research, screening, and AI development

A method for detecting glaucoma based only on optical coherence tomography (OCT) is of potential value for routine clinical decisions, for inclusion criteria for research studies and trials, for large-scale clinical screening, as well as for the development of artificial intelligence (AI) decision models. Recent work suggests that the OCT probability (p-) maps, also known as deviation maps, can play a key role in an OCT-based method. However, artifacts seen on the p-maps of healthy control eyes can resemble patterns of damage due to glaucoma. We document in section 2 that these glaucoma-like artifacts are relatively common and are probably due to normal anatomical variations in healthy eyes. We also introduce a simple anatomical artifact model based upon known anatomical variations to help distinguish these artifacts from actual glaucomatous damage. In section 3, we apply this model to an OCT-based method for detecting glaucoma that starts with an examination of the retinal nerve fiber layer (RNFL) p-map. While this method requires a judgment by the clinician, sections 4 and 5 describe automated methods that do not. In section 4, the simple model helps explain the relatively poor performance of commonly employed summary statistics, including circumpapillary RNFL thickness. In section 5, the model helps account for the success of an AI deep learning model, which in turn validates our focus on the RNFL p-map. Finally, in section 6 we consider the implications of OCT-based methods for the clinic, research, screening, and the development of AI models.

Bruch Membrane Opening Minimum Rim Width and Retinal Nerve Fiber Layer Helps Differentiate Compressive Optic Neuropathy From Glaucoma

PURPOSE

To compare optical coherence tomography-measured Bruch membrane opening minimum rim width (MRW), peripapillary retinal nerve fiber layer (pRNFL) measurements, and MRW:pRNFL ratios in eyes with compressive optic neuropathy (CON) and glaucoma and controls, and evaluate the ability of these parameters to differentiate CON from glaucoma.

DESIGN

Prospective, cross-sectional study.

METHODS

Setting: Single-center tertiary hospital and outpatient clinic.

PATIENT POPULATION

One hundred fifteen eyes of 77 participants, 34 with CON from chiasmal lesions, 21 with glaucoma, and 22 healthy controls.

OBSERVATION PROCEDURES

Optical coherence tomography-measured MRW, pRNFL, and MRW:pRNFL ratios for each optic disc sector and global average.

MAIN OUTCOME MEASURES

MRW, pRNFL, and MRW:pRNFL ratios compared using generalized estimated equations. Area under the receiver operating characteristic curve and positive and negative likelihood ratios were calculated.

RESULTS

MRW and pRNFL measurements were significantly reduced in CON and glaucoma compared with controls. In glaucoma, MRW was thinner than in CON in the global, inferotemporal, superonasal, inferonasal, and vertical average measurements, but a significant overlap was observed in many parameters. MRW:pRNFL ratios increased the ability to discriminate between CON and glaucoma, as shown by the high area under the receiver operating characteristic curve, high positive likelihood ratios, and low negative likelihood ratios, especially in the nasal disc sector and the nasal and temporal average.

CONCLUSIONS

MRW measurements alone cannot reliably distinguish CON from glaucoma, but the combination of MRW, pRNFL, and MRW:pRNFL ratios significantly improves accuracy. When comparing the 2 conditions, MRW:pRNFL ratios yielded higher area under the receiver operating characteristic curve and positive and negative likelihood ratios, suggesting this parameter may be helpful in clinical practice.

A normative database of A-scan data using the Heidelberg Spectralis Spectral Domain Optical Coherence Tomography machine

Purpose

To develop the first normative database of macular and circumpapillary scans with reference values at the level of the A-scan using the Heidelberg Spectralis Optical Coherence Tomography (OCT) machine.

Methods

This study is a retrospective cross sectional analysis of macular and circumpapillary OCT scans of healthy individuals. All participants had a full ophthalmic examination, including best corrected visual acuity, intraocular pressure, biomicroscopy, posterior segment examination and OCT scan. The volume and thickness of each of the nine Early Treatment Diabetic Retinopathy zones at the macula were analysed for the total retinal thickness, retinal nerve fibre layer (RNFL), ganglion cell layer (GCL) and inner plexiform layer (IPL). The thickness of the circumpapillary RNFL was analysed at the disc. Associations between age, gender, refractive error and OCT measurements were explored. De-identified A-scans were extracted from the OCT machine as separate tab-separated text file and made available according to the data sharing statement.

Results

Two-hundred eyes from 146 participants were included of which 69 (47%) were female. The mean age (SD) was 48.52 (17.52). Participants were evenly distributed across four age groups and represented nine broad ethnic groups in proportions comparable to the local distribution. All the macular scans were 20° x 20° (5.9 mm x 5.9 mm), with a total scan density between 12,800 and 49,152 A-scans. The peripapillary scans were all 12° (3.5 mm), at a scan density of 768 A-scans. The mean retinal, GCL and IPL volumes were significantly greater in males than females. Mean peripapillary RNFL thickness did not differ significantly between males and females. Age and total retinal volume (r = –0.2561, P = 0.0003), GCL volume (–0.2911, P < 0.0001) and IPL volume (–0.3194, P < 0.0001) were negatively correlated. The IPL had the strongest three significant negatively associated segments; superior inner IPL (r = –0.3444, P < 0.0001), nasal outer IPL (r = –0.3217, P < 0.0001) and inferior inner IPL (r = –0.3179, P < 0.0001). The temporal inner macular RNFL showed a statistically significant positive correlation (r = 0.1929, P = 0.0062) with age. The only significant association between age and thickness at the peripapillary disc scan was the superior temporal sector (r = –0.1910, P = 0.0067). All retinal layers were negatively correlated for refractive error, except for the central RNFL which was positively correlated (r = 0.1426, P = 0.044).

Conclusion

This study provides a normative database of macular and circumpapillary scans with reference values at the level of the A-scan using the Heidelberg Spectralis Optical Coherence Tomography (OCT) machine.

Bruch's Membrane Opening Minimum Rim Width Provides Objective Differentiation between Glaucoma and Nonglaucomatous Optic Neuropathies

PURPOSE

A challenging clinical scenario is distinguishing between normal tension glaucoma (NTG) and non-glaucomatous optic neuropathies (NGON). The key to the assessment remains identifying the presence of optic nerve head cupping. Recent optical coherence tomography (OCT) measurements now allow objective assessment of cupping by minimum rim width at Bruch's membrane opening (MRW-BMO). This study assessed the hypothesis that the MRW-BMO measurement quantifies cupping and therefore can differentiate between NTG and NGON.

DESIGN

Diagnostic evaluation with area under the curve.

METHODS

Setting: multicenter tertiary hospitals and outpatient clinics.

PATIENT POPULATION

81 eyes of 81 patients were enrolled, 27 with NTG and 54 with NGON, including ischemic optic neuropathy, previous optic neuritis, and compressive and inherited optic neuropathies. All NGON patients with intraocular pressure >21 mm Hg, narrow drainage angles, or a family history of glaucoma were excluded. Observational procedure: optic disc OCT images were obtained of both the retinal nerve fiber layer thickness and the MRW-BMO.

MAIN OUTCOME MEASUREMENTS

the utility of the MRW-BMO in differentiating GON from NGON was assessed using the area under the curve (AUC) estimated from a logistic regression model.

RESULTS

The 5-fold cross-validated AUC for glaucoma versus nonglaucoma from logistic regression models using MRW-BMO values from all sectors was 0.95 (95% confidence interval: 0.86-1.00).

CONCLUSIONS

The measurement of MRW-BMO effectively differentiates between NTG and NGON with a high level of sensitivity and specificity. Incorporating this measurement into routine glaucoma assessment may provide a robust method of assisting clinicians to improve diagnosis and therefore treatment of optic nerve diseases.

Prognostic value of macular ganglion cell layer thickness for visual outcome in parasellar tumors

PURPOSE

Optic nerve compression by mass lesions at the optic chiasm leads to loss of visual function which can be recovered after decompression surgery. In this study, we evaluated the prognostic ability of macular ganglion cell layer (mGCL) thickness measured with spectral-domain optical coherence tomography (SD-OCT) for predicting postoperative visual outcome of compressive optic neuropathy (CON) related to parasellar tumors.

METHODS

This observational cohort study used data from the Department of Neurosurgery and Ophthalmology, Seoul National University Bundang Hospital between 2013 and 2018. Seventy-nine eyes from 79 patients with CON due to parasellar tumors who underwent surgery were included. Patients were divided into either a visual recovery group or a non-recovery group according to the degree of postoperative visual field (VF) impairment. SD-OCT scanning with automated segmentation was performed to measure the circumpapillary retinal nerve fiber layer (cpRNFL) and the mGCL thickness in the nine macular subfields as defined by the ETDRS and 8 × 8 posterior pole grid. Correlations between preoperative cpRNFL thickness, mGCL thickness and postoperative VF sensitivity were assessed. The prognostic ability of mGCL thickness for predicting visual recovery after surgical decompression in each ETDRS subfield and posterior pole grid quadrant was evaluated.

RESULTS

The central inferonasal and superonasal quadrant mGCL thicknesses measured by the 8 × 8 posterior pole grid showed the best predictability of postoperative visual outcome (AUROC = 0.963 and 0.953, respectively), which was superior to the prognostic power of the average cpRNFL. The central inferonasal quadrant mGCL thickness significantly correlated with the superotemporal quadrant VF sensitivity (R² = 0.589).

CONCLUSIONS

The mGCL thickness in the central nasal quadrants measured by SD-OCT is an excellent predictor of visual recovery after chiasmal decompression.

Different damage patterns of retinal nerve fiber layer and ganglion cell-inner plexiform layer between early glaucoma and non-glaucomatous optic neuropathy

AIM

To compare the damage pattern of the peripapillary retinal nerve fiber layer (pRNFL) and the macular ganglion cell-inner plexiform layer (mGCIPL) between early glaucomatous and non-glaucomatous optic neuropathy (EGON and NGON).

METHODS

It is a cross-sectional study. Thirty-eight healthy controls, 74 EGONs and 70 NGONs with comparable average pRNFL loss were included. The NGON group included 23 eyes of optic neuritis (ON), 13 eyes of hereditary optic neuropathy (HON), 19 eyes of toxic optic neuropathy (TON) and 15 eyes of compressive neuropathy (CON). The sectoral pRNFL and mGCIPL thickness obtained by high definition optical coherence tomography were analyzed.

RESULTS

Compared to normal controls, the pRNFL thickness in all quadrants showed a decrease in both EGON and NGON group (P<0.001), but the average pRNFL thickness of EGON group was not different to that of NGON group (P=0.94). The inferior and superior pRNFL was thinner in EGON group compared to NGON group (P<0.001). The temporal pRNFL was thinner in NGON group compared to EGON group (P<0.001). No statistically significant difference was found in nasal pRNFL between EGON and NGON. While the nasal pRNFL was thinner in CON than other three types of NGON (P=0.01), no statistically significant difference was found in other three quadrantal pRNFL among the four types of NGON (P>0.05). The mGCIPL of EGON and NGON group were thinner than control group (P<0.001). In EGON group the severest sites of mGCIPL reduction was located at inferotemporal and inferior sectors. While, compared to EGON group, the average mGCIPL of NGON group were significantly thinner, especially in superonasal and inferonasal sectors (P<0.001).

CONCLUSION

The damage pattern of pRNFL and mGCIPL caused by glaucoma is distinct from other NGON such as ON, TON, HON and CON, and this characteristic damage pattern is helpful in differentiating early glaucoma from other NGON.

Glaucoma-like Parapapillary Choroidal Microvasculature Dropout in Patients with Compressive Optic Neuropathy

PURPOSE

To characterize peripapillary choroidal microvasculature dropout (MvD) in patients with compressive optic neuropathy (CON) as compared with those with open-angle glaucoma (OAG) using OCT angiography (OCTA).

DESIGN

Cross-sectional, observational study.

PARTICIPANTS

Eighty-eight eyes of 44 patients with CON; 88 eyes of 88 patients with OAG matched by age, spherical error, and OCT-determined retinal nerve fiber layer thickness (RNFLT); and 88 eyes of 44 control participants matched by age and spherical error.

METHODS

Peripapillary microvasculature was evaluated, and peripapillary vessel density was measured in en face images segmented into inner-retinal and choroidal layers using swept-source OCTA. An MvD was defined as a focal sectoral capillary dropout with no visible microvascular network in the choroidal layer.

MAIN OUTCOME MEASURES

Comparative characteristics of MvD in eyes with CON and OAG.

RESULTS

Microvasculature dropout was observed in 30 eyes (34.1%) of 22 patients (50.0%) with CON, and in 48 eyes of 48 patients (54.5%) with OAG (P = 0.011). All MvDs in the CON group were located in the temporal parapapillary sector, whereas MvDs in the OAG group were located in the temporal-inferior (n = 36) and temporal-superior (n = 4) sectors. At their locations, MvDs in the CON group were accompanied by significant reductions in retinal vessel density and RNFLT, but this was not observed in the OAG group. The presence of MvD was associated significantly with female gender (P = 0.020) and thinner global retinal nerve fiber layer (P = 0.006) in the CON group, but not in the OAG group.

CONCLUSIONS

OCT angiography of the peripapillary area showed retinal and choroidal microvasculature impairment in patients with both CON and OAG. However, the features and associated characteristics of MvD differed between these groups, suggesting that the pathogenesis of peripapillary microvascular impairment may be diverse.

Discriminating glaucomatous and compressive optic neuropathy on spectral-domain optical coherence tomography with deep learning classifier

BACKGROUND/AIMS

To assess the performance of a deep learning classifier for differentiation of glaucomatous optic neuropathy (GON) from compressive optic neuropathy (CON) based on ganglion cell-inner plexiform layer (GCIPL) and retinal nerve fibre layer (RNFL) spectral-domain optical coherence tomography (SD-OCT).

METHODS

Eighty SD-OCT image sets from 80 eyes of 80 patients with GON along with 81 SD-OCT image sets from 54 eyes of 54 patients with CON were compiled for the study. The bottleneck features extracted from the GCIPL thickness map, GCIPL deviation map, RNFL thickness map and RNFL deviation map were used as predictors for the deep learning classifier. The area under the receiver operating characteristic curve (AUC) was calculated to validate the diagnostic performance. The AUC with the deep learning classifier was compared with those for conventional diagnostic parameters including temporal raphe sign, SD-OCT thickness profile and standard automated perimetry.

RESULTS

The deep learning system achieved an AUC of 0.990 (95% CI 0.982 to 0.999) with a sensitivity of 97.9% and a specificity of 92.6% in a fivefold cross-validation testing, which was significantly larger than the AUCs with the other parameters: 0.804 (95% CI 0.737 to 0.872) with temporal raphe sign, 0.815 (95% CI 0.734 to 0.896) with superonasal GCIPL and 0.776 (95% CI 0.691 to 0.860) with superior GCIPL thicknesses (all p<0.001).

CONCLUSION

The deep learning classifier can outperform the conventional diagnostic parameters for discrimination of GON and CON on SD-OCT.

Ganglion Cell - Inner Plexiform Layer Damage in Diabetic Patients: 3-Year Prospective, Longitudinal, Observational Study

Diabetes is expected to accelerate age-related ganglion cell–inner plexiform layer (GC-IPL) loss, but there is limited information on the rate of reduction in GC-IPL thicknesses. We aimed to evaluate the reduction rate of GC-IPL thickness in diabetic patients, and to compare the rates between patients without and with diabetic retinopathy (DR). We included 112 eyes of 112 patients with diabetes [49 eyes without DR (no-DR group) and 63 eyes with mild to moderate non-proliferative DR (NPDR group)] and 63 eyes of 63 normal controls (control group) in this study. Macular GC-IPL thickness in all participants was measured for 3 years at 1-year intervals. The reduction rates of GC-IPL thickness were determined by linear mixed models and compared among the three groups. The estimated reduction rates of the average GC-IPL thickness in the no-DR (−0.627 μm/year) and NPDR (−0.987 μm/year) groups were 2.26-fold (p = 0.010) and 3.56-fold (p = 0.001) faster, respectively, than the control group (−0.277 μm/year). Age, duration of diabetes, and baseline average GC-IPL thickness were associated with longitudinal changes in average GC-IPL thickness. The GC-IPL reduction rate was significantly faster in diabetic patients, with and without DR. Physicians should therefore be aware that GC-IPL damage continues even if there is no DR.

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.

Longitudinal Changes in the Peripapillary Retinal Nerve Fiber Layer Thickness of Patients With Type 2 Diabetes

Importance

Type 2 diabetes is expected to accelerate age-related peripapillary retinal nerve fiber layer (pRNFL) loss, but limited information on the rate of reduction in pRNFL thicknesses in patients with type 2 diabetes is available.

Objective

To investigate longitudinal changes in pRNFL thickness in patients with type 2 diabetes, with or without diabetic retinopathy (DR).

Design, Setting, and Participants

A total of 164 eyes of 63 healthy individuals and 101 patients with type 2 diabetes (49 patients without DR [non-DR group] and 52 patients with mild to moderate nonproliferative DR [NPDR group]) were enrolled in this prospective, longitudinal, observational study from January 2, 2013, through February 27, 2015. Participants were followed up for 3 years, and the peripapillary mean and sector RNFL thicknesses were measured at 1-year intervals. The mean rate of pRNFL loss was estimated using a linear mixed model and compared among the 3 groups. Follow-up was completed on March 16, 2018, and data were analyzed from April 2 through July 27, 2018.

Exposure

Type 2 diabetes.

Main Outcomes and Measures

The rate of reduction in pRNFL thickness in patients with type 2 diabetes.

Results

A total of 164 participants (88 women [53.7%]; mean [SD] age, 58.2 [8.7] years) were included in the study analysis. The mean (SD) age of the control group was 56.5 (9.3) years (39 women [61.9%]); the non-DR group, 59.1 (9.4) years (26 women [53.1%]); and the NPDR group, 59.4 (11.0) years (23 women [44.2%]). Mean (SD) duration of type 2 diabetes was 7.1 (4.4) years in the non-DR group and 13.2 (8.4) years in the NPDR group. The baseline mean (SD) pRNFL thickness was 96.2 (11.0) μm in the control group, 93.5 (6.4) μm in the non-DR group, and 90.4 (7.9) μm in the NPDR group. During 3 years of follow-up, these values decreased to 95.0 (9.2) μm in the control group, 90.3 (6.4) in the non-DR group, and 86.6 (7.9) μm in the NPDR group. In a linear mixed model, the estimated mean pRNFL loss was -0.92 μm/y in the non-DR group (P < .001) and -1.16 μm/y in the NPDR group (P < .001), which was 2.9-fold (95% CI, 1.1-14.8; P = .003) and 3.3-fold (95% CI, 1.4-18.0; P < .001) greater, respectively, than that of the control group (-0.35 μm/y; P = .01).

Conclusions and Relevance

Progressive reduction of pRNFL thickness was observed in healthy controls and patients with type 2 diabetes without and with DR; however, type 2 diabetes was associated with a greater loss of pRNFL regardless of whether DR was present. These findings suggest that pRNFL loss may occur in people with type 2 diabetes even in the absence of DR progression.

Variable structure and function relationship of compressive optic neuropathy at the time of diagnosis

Purpose

To illustrate the structure–function relationship of compressive optic neuropathy (CON) at the time of diagnosis.

Patients and methods

Thirty-two eyes of newly diagnosed suprasellar CON and 60 healthy eyes were included in the study. The peripapillary retinal nerve fiber layer (RNFL) thickness and macular ganglion cell-inner plexiform layer (GCIPL) thickness were obtained using Cirrus spectral domain optical coherence tomography (SD-OCT). CON eyes were stratified based on the similar degree and pattern of both RNFL and GCIPL.

Results

From 32 eyes of newly diagnosed suprasellar CON eyes, 27 eyes had a predominantly nasal hemiretina thinning of macular GCIPL, 4 eyes showed a generalized macular thinning, and 1 eye showed a predominantly superior macular thinning. The corresponding temporal peripapillary RNFL thinning with nasal hemiretina GCIPL thinning were inconsistently manifested. Structure–function analysis of stratified CON eyes with similar thinning profiles showed that a range rather than a fixed value of visual field loss based on mean deviation (MD) index was associated to each thinning profile. The maximal limit of visual field loss range was ubiquitously nonrestricted to any structural thinning profile. While the minimal limit of the associated MD range was gradually reduced from 0 to about −16.0 dB, the nasal hemiretina macular GCIPL thinning was the only manifestation and decreased from 75 to 45 µm. However, the different degrees of temporal hemiretina macular GCIPL and superior–inferior peripapillary RNFL thinning were only seen in 10 of 32 eyes of which their nasal hemiretina GCIPL and temporal RNFL thinning had reached significant thinning. Interestingly when present, the minimal limit of associated MD range continued to decrease from −16.0 to −32.0 dB.

Conclusion

CON eyes can present with variable structure and function relationship at the time of diagnosis. Using structural parameters at the time of diagnosis to predict the prognosis should be used with caution.

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Modern neuro-ophthalmological evaluation of patients with pituitary disorders

Pituitary adenomas can manifest as ophthalmological symptoms, such as decreased vision, impaired visual field or diplopia. It is important to recognize these neuro-ophthalmological syndromes to achieve early diagnosis and treatment and to improve prognosis. Currently, ophthalmological examination includes precise measuring instruments, such as optical coherence tomography (OCT), which allows the evaluation of optic atrophy related to compression of the anterior optic tract. These measurements are reproducible and are useful for diagnostic and prognostic evaluation. In this review, we describe the ophthalmological syndromes associated with pituitary tumours: anterior optic pathway compression, followed by oculomotor disorders and pituitary apoplexy.

An evidence-based approach to the routine use of optical coherence tomography

Optical coherence tomography is an imaging technology that has revolutionised the detection, assessment and management of ocular disease. It is now a mainstream technology in clinical practice and is performed by non-specialised personnel in some settings. This article provides a clinical perspective on the implications of that movement and describes best practice using multimodal imaging and an evidence-based approach. Practical, illustrative guides on the interpretation of optical coherence tomography are provided for three major diseases of the ocular fundus, in which optical coherence tomography is often crucial to management: age-related macular degeneration, diabetic retinopathy and glaucoma. Topics discussed include: cross-sectional and longitudinal signs in ocular disease, so-called 'red-green' disease whereby clinicians rely on machine/statistical comparisons for diagnosis in managing treatment-naïve patients, and the utility of optical coherence tomography angiography and machine learning.

Optic nerve compression: the role of the lamina cribrosa and translaminar pressure

AIM

To describe the morphological changes of the lamina cribrosa (LC) in patients with optic nerve compression.

METHODS

Cross-sectional study. Twenty eyes with optic nerve compression, affected by Graves' ophthalmopathy (GO) were compared with 18 refractive error-matched healthy eyes. The following examinations were performed: best-corrected visual acuity (BCVA), intraocular pressure, optic nerve echography, visual field, SD-OCT including the retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), and LC thickness and extent.

RESULTS

A-scan revealed significant differences in the subarachnoid space (SAS) between the affected and control groups. LC thickness and LC area were 233 µm (SD 23) and 0.41 mm² (SD 0.19), respectively. Average GCC thickness (P=0.0005), LC thickness (P=0.001), MD (P=0.001) and PSD (P=0.001) differed significantly between the two groups; whereas LC area (P=0.2) and average RFNL (P=0.1) did not.

CONCLUSION

Optic nerve compression reduces the SAS thereby altering the morphology of LC thickness and causing GCC damage.

Variations in optic nerve head morphology by intraocular pressure in open-angle glaucoma

PURPOSE

To compare optic disc topography in eyes in three intraocular pressure (IOP) groups of <15 mmHg, 15-20 mmHg, and ≥21 mmHg using spectral domain optical coherence tomography (SD-OCT) and confocal scanning laser ophthalmoscopy, adjusting for the degree of damage, as measured by retinal nerve fiber layer (RNFL) thickness and average visual field loss.

METHODS

A total of 184 eyes of 112 patients with primary open-angle glaucoma were recruited into groups based on baseline untreated intraocular pressure (IOP) of <15 mmHg (normal-tension glaucoma [NTG], very low), 15-20 mmHg (NTG, medium), or ≥21 mmHg (high-tension glaucoma [HTG]). Patients underwent scanning laser ophthalmoscopy, SD-OCT, and Humphrey visual field testing. Univariate and multivariate models were created, accounting for degree of retinal ganglion cell (RGC) loss by either OCT RNFL thickness or visual field mean deviation (MD).

RESULTS

Univariate and multivariate analyses demonstrated no morphological differences in HRT or OCT parameters among IOP groups that met Bonferroni-corrected statistical significance when using either MD or OCT RNFL as the damage criterion (p < 0.0063). The mean cup depth was shallower for the IOP <15 mmHg group than the IOP ≥21 mmHg group (p < 0.05) for both MD (p < 0.011) and OCT RNFL (p < 0.014).

CONCLUSION

Normal-tension and high-tension glaucoma are not distinguishable by optic nerve head topography with HRT and OCT when the degree of damage by Humphrey visual field testing is taken into account.

Chiasmal syndrome: Clinical characteristics in patients attending an ophthalmological center

Purpose

To present the clinical characteristics of a group of patients with the diagnosis of chiasmal syndrome who attended a large ophthalmological institute.

Methods

Retrospective, observational clinical study with the review of medical records of patients with a diagnosis of chiasmal syndrome. The following variables were assessed: demographic characteristics, chief complaint upon presentation, best-corrected visual acuity (BCVA), presence or absence of diplopia, pupillary responses, optic nerve head morphology, etiology, and results from the ancillary tests including Ishihara test, Goldmann visual field (GVF) perimetry and neuroimaging.

Results

A total of 104 met the inclusion criteria, with a median age of 52 years (range 4-86 years). Fifty-four patients (51.9%) were referred to our institution with a diagnosis of a causative etiology for chiasmal syndrome, while in 50 (48.1%) the diagnosis was performed at our center. The most common presenting symptom was low visual acuity in 57 patients (54.8%), and the most common GVF defect was bitemporal hemianopsia in 39 patients (78 eyes, 39.8%). Pupillary abnormalities were present in 58 patients (55.7%), the optic nerve revealed pallor at any degree in 67 patients (64.4%) and the Ishihara test was affected in 65 patients (62.5%). The most common diagnosis was pituitary macroadenoma.

Conclusion

The ophthalmologist participates in the diagnosis and rehabilitation of patients with chiasmal syndrome. Low visual acuity is the most common symptom at presentation, and bitemporal hemianopia the most frequent GVF defect. Examination of the optic nerve head and pupillary responses, and ancillary tests including Ishihara test and neuroimaging are relevant for diagnosis.

Optical coherence tomography and neurodegeneration: are eyes the windows to the brain?

INTRODUCTION

Central nervous system (CNS) pathologies have ocular manifestations due to direct and/or retrograde degeneration of the visual pathways, most often related to a direct injury to the optic nerve, retinal ganglion cells and/or its surrounding cells. These ocular manifestations can be recognized and monitored by a non-invasive technique called Optical Coherence Tomography (OCT).

AREAS COVERED

This review article describes the OCT technique and its application in various neurological pathologies. OCT helps in the measurement of retinal nerve fiber layer thickness (RNFLT) and macular thickness which consists of retinal ganglion cells. OCT provides a near-histological level of image resolution up to 5µm by using principles of interferometry that can detect CNS inflammatory, as well as degenerative, pathologies (i.e Multiple Sclerosis, Parkinson's disease and Alzheimer's Disease etc.) at initial clinical and possibly subclinical stages. Expert Commentary: RNFLT and macular volumes measured by OCT can serve as biomarkers for early recognition and progression of a variety of neurological disease, although the specificity of these findings in clinical diagnosis requires further refinement. An early biomarker can help in an earlier therapeutic intervention and thus preventing further progression and provide the opportunity for possible regenerative interventions of the underlying disease process. With the advent of "next-generation" OCT technology an increase in use is foreseen in research as well as in clinical practice.

One Year of Glaucoma Research in Review-2013 to 2014

PURPOSE

The purpose of this study was to provide the practicing clinical ophthalmologist with an update on relevant glaucoma literature published from 2013 to 2014.

DESIGN

This study is a literature review.

METHODS

The authors conducted a 1-year (October 1, 2013, to September 30, 2014) English-language glaucoma literature search on PubMed of articles containing "glaucoma" or "glaucomatous" with title/abstract as a filter. Medical subject headings filtered searching was not performed because of the newness of the reviewed material.

RESULTS

Literature search yielded 2314 articles, after which we excluded reviews and letters to the editor. We highlighted articles featuring new or updated approaches to the pathophysiology, diagnosis, or treatment of glaucoma and gave preference to human research.

CONCLUSIONS

This review features literature that is of interest to ophthalmologists in practice and also highlights studies that may provide insight on future developments applicable to clinical ophthalmology.

Retinal nerve fiber layer and ganglion cell complex thicknesses measured with spectral-domain optical coherence tomography in eyes with no light perception due to nonglaucomatous optic neuropathy

PURPOSE

To measure retinal nerve fiber layer thickness (RNFLT) and ganglion cell complex thickness (GCCT) in eyes with no light perception due to nonglaucomatous optic neuropathy using spectral-domain optical coherence tomography.

METHODS

Fourteen eyes of 14 patients (9 women, 5 men; mean age 56.0 ± 16.6 (standard deviation) years] with no light perception due to optic neuropathy were recruited to this retrospective study. Only clinically stable eyes were included. Eyes were imaged at least 6 months after the onset of the disease. Five patients lost light perception due to traumatic optic neuropathy, four patients had ischemic optic neuropathy, two patients had optic neuritis, two patients had compressive optic neuropathy, and one patient had optic nerve atrophy. Global and quadrant RNFLTs were measured with the Cirrus HD-optical coherence tomography (OCT) system; global and hemisphere GCCTs were measured by spectral-domain OCT (RTVue OCT system). Only reliable OCT images were used for further analysis.

RESULTS

Reliable RNFL images were obtained in 12 eyes, and reliable GCC images were obtained in 11 eyes. Global, superior, temporal, inferior, and nasal RNFLT were 57.5 ± 6.7, 60.6 ± 7.6, 54.1 ± 11.2, 59.7 ± 9.5, and 55.6 ± 7.4 µm, respectively. Global, superior, and inferior GCC thicknesses were 68.8 ± 9.6, 70.7 ± 12.2, and 67.8 ± 8.8 µm, respectively.

CONCLUSIONS

A considerable proportion of RNFL and GCC remained in eyes with no light perception vision. Clinicians should take this into account when evaluating the severity of optic neuropathy from OCT-measured RNFLT and GCCT.