Quantifying peripapillary vessel density and retinal nerve fibre layer in type 1 diabetic children without clinically detectable retinopathy using OCTA

AIM:To quantify changes in radial peripapillary capillary vessel density(ppVD)and the peripapillary retinal nerve fiber layer(pRNFL)in children with type 1 diabetes without clinical diabetic retinopathy by optical coherence tomography angiography(OCTA),providing a basis for early retinopathy in children with type 1 diabetes.METHODS:This was a retrospective study.A total of 30 patients(3–14y)with type 1 diabetes without clinical diabetic retinopathy(NDR group)were included.A total of 30 age-matched healthy subjects were included as the normal control group(CON group).The HbA1c level in the last 3mo was measured once in the NDR group.The pRNFL thickness and ppVD were automatically measured,and the mean pRNFL and ppVD were calculated in the nasal,inferior,temporal,and superior quadrants.The changes in ppVD and pRNFL in the two groups were analyzed.RESULTS:Compared with CON group,the nasal and superior ppVDs decreased in the NDR group(all P<0.01).The thickness of the nasal pRNFL decreased significantly(P<0.01),while the inferior,temporal and superior pRNFLs slightly decreased but not significant in the NDR group(all P>0.05).Person and Spearman correlation analysis of ppVD and pRNFL thickness in each quadrant of the NDR group showed a positive correlation between nasal and superior(all P<0.01),while inferior and temporal had no significant correlation(all P>0.05).There was no significant correlation between the HbA1c level and ppVD and pRNFL in any quadrant(all P>0.05).There was no significant correlation between the course of diabetes mellitus and ppVD and pRNFL in any quadrant(all P>0.05).CONCLUSION:ppVD and pRNFL decrease in eyes of children with type 1 diabetes before clinically detectable retinopathy and OCTA is helpful for early monitoring.

The correlation between rat retinal nerve fiber layer thickness around optic disc by using optical coherence tomography and histological measurements

·AIM: To explore the correlation between the retinal nerve fiber layer (RNFL) thickness by using optical coherence tomography (OCT) and by histological measurements in normal adult rats and optic nerve transected rats. · METHODS: The RNFL thickness of 36 rats was scanned in a circle 3.46mm far from the optic disc by OCT. The two experimental groups were the normal group ( =20 rats) and the optic nerve transected group ( =16 rats). The latter group included 4 groups ( =4 /group) surviving for 1 day, 3, 5 and 7 days. Then the RNFL thickness of the same retina area was also measured by NF -200 immunohistochemical staining method. Linear regression was used to analyze the correlation between the data obtained from these two methods. ·RESULTS: The RNFL thickness of normal right eyes around optic disc by OCT was 72.35 ±5.71μm and that of the left eyes was 72.65 ±5.88μm ( =0.074). The RNFL thickness of the corresponding histological section by immunohistochemistry was 37.54 ±4.05μm (right eyes) and 37.38 ±4.23μm (left eyes) ( =0.059). There was a good correlation between the RNFL thickness measured by OCT and that measured by histology (R 2 =0.8131). After optic nerve transection, the trend of the RNFL thickness was thinner with the prolonged survival time. The correlation of the thickness detected by the above two methods was approximately (R 2 =0.8265). Value of the RNFL thickness in rats around optic disc measured by OCT was obviously higher than that measured by common histological measurement in normal adult rats and optic nerve transected rats. ·CONCLUSION: The RNFL thickness measured by OCT has a strong correlation with that measured by histological method. Through OCT scanning, we found that the thickness of RNFL gradually becomes thinner in a time-dependent manner.

Optical coherence tomography assessed retinal nerve fiber layer thickness in patients with Alzheimer's disease:a meta-analysis

AIM:To investigate the difference of retinal nerve fiber layer(RNFL) thickness between Alzheimer's disease patients and normal people,so as to provide clue for the early diagnosis of Alzheimer's disease.· METHODS:The articles on the association of RNFL thickness and Alzheimer's disease were retrieved by searching international and national databases.The qualified articles were assessed by meta analysis with Stata11.0 software.The results were pooled using weighted mean difference(WMD) with a corresponding 95% confidence interval(CI).· RESULTS:Totally 7 studies enrolled 324 eyes were included in the meta-analysis.The results of meta analysis showed that in AD patients,there was a significant average RNFL thickness reduction compared with the control group [WMD=-17.561,95%CI:(-23.971,-11.151)].There were significant differences in superior,inferior,nasal and temporal RNFL thickness between the two groups.WMD with a 95%CI were [-18.829,95%CI:(-25.915,-11.743);P<0.05],[-25.775,95%CI:(-34.304,-17.247);P <0.05],[-16.877,95%CI:(-29.141,-4.613);P<0.001] and [-14.565,95%CI:(-28.002,-1.128);P<0.001] respectively.Begg's test and Egger's test did not show significant difference,funnel plot was basically symmetrical,indicating that there was no publication bias existed.· CONCLUSION:There are significant differences in the RNFL thickness in all quadrants between the two groups.RNFL thickness is reduced in AD patients compared with the control group.·

Optical coherence tomography with or without enhanced depth imaging for peripapillary retinal nerve fiber layer and choroidal thickness

AIM：To assess peripapillary retinal nerve fiber layer（RNFL）and choroidal thickness obtained with enhanced depth imaging（EDI）mode compared with those obtained without EDI mode using Heidelberg Spectralis optical coherence tomography（OCT）.METHODS：Fifty eyes of 25 normal healthy subjects and32 eyes of 20 patients with different eye diseases were included in the study.All subjects underwent 3.4 mm diameter peripapillary circular OCT scan centered on the optic disc using both the conventional and the EDI OCT protocols.The visualization of RNFL and choroidoscleral junction was assessed using an ordinal scoring scale.The paired t-test,intraclass correlation coefficient（ICC）,95%limits of agreement（LoA）,and Bland and Altman plots were used to test the agreement of measurements.RESULTS：The visibility score of RNFL obtained with and without EDI was of no significant difference（P=0.532）,the visualization of choroidoscleral junction was better using EDI protocol than conventional protocol（P〈0.001）.Peripapillary RNFL thickness obtained with EDI was slightly thicker than that obtained without EDI（103.25±9.42μm vs 101.87±8.78μm,P=0.010）.The ICC of the two protocols was excellent with the value of 0.867 to 0.924,the 95%LoA of global RNFL thickness was between-10.0 to 7.4μm.Peripapillary choroidal thickness obtained with EDI was slightly thinner than that obtained without EDI（147.23±51.04μm vs 150.90±51.84μm,P〈0.001）.The ICC was also excellent with the value of 0.960 to 0.987,the 95%LoA of global choroidal thickness was between-12.5 to 19.8μm.CONCLUSION：Peripapillary circular OCT scan with or without EDI mode shows comparable results in the measurement of peripapillary RNFL and choroidal thickness.

Optical coherence tomography evaluation of retinal nerve fiber layer thickness in non-arteritic anterior ischemic optic neuropathy and primary open angle glaucoma:a systematic review and Meta-analysis

AIM:To assess the differences in average and sectoral peripapillary retinal nerve fiber layer(p RNFL)thickness using spectral domain optical coherence tomography(SD-OCT)in patients with non-arteritic anterior ischemic neuropathy(NAION)compared with those with primary open angle glaucoma(POAG).METHODS:A comprehensive literature search of the Pub Med,Cochrane Library,and Embase databases were performed prior to October,2021.Studies that compared the p RNFL thickness in NAION eyes with that in POAG eyes with matched mean deviation of the visual fields were included.The weighted mean difference(WMD)with 95%confidence interval(CI)was used to pool continuous outcomes.RESULTS:Ten cross-sectional studies(11 datasets)comprising a total of 625 eyes(278 NAION eyes,347 POAG eyes)were included in the qualitative and quantitative analyses.The pooled results demonstrated that the superior p RNFL was significantly thinner in NAION eyes than in POAG eyes(WMD=-6.40,95%CI:-12.22 to-0.58,P=0.031),whereas the inferior p RNFL was significant thinner in POAG eyes than in NAION eyes(WMD=11.10,95%CI:7.06 to 15.14,P≤0.001).No difference was noted concerning the average,nasal,and temporal p RNFL thickness(average:WMD=1.45,95%CI:-0.75 to 3.66,P=0.196;nasal:WMD=-2.12,95%CI:-4.43 to 0.19,P=0.072;temporal:WMD=-1.24,95%CI:-3.96 to 1.47,P=0.370).CONCLUSION:SD-OCT based evaluation of inferior and superior p RNFL thickness can be potentially utilized to differentiate NAION from POAG,and help to understand the different pathophysiological mechanisms between these two diseases.Further longitudinal studies and studies using eight-quadrant or clock-hour classification method are required to validate the obtained findings.

Retinal thickness and vascular parameters using optical coherence tomography in Alzheimer's disease:a meta-analysis

Examining the retinal tissue has the potential to provide a unique method and technique to quantify Alzheimer’s disease-related changes in participants at various stages of the disease.In this metaanalysis,we aimed to investigate the association of various optical coherence tomography parameters with Alzheimer’s disease and whether retinal measurements can be used to diffe rentiate between Alzheimer’s disease and control subjects.Scientific databases including Google Schola r,Web of Science,and PubMed were systematically searched for published articles that evaluated retinal nerve fiber layer thickness and retinal microvascular network in Alzheimer’s disease and control subjects.Seventy-three studies(5850 participants,including 2249 Alzheimer’s disease patients and 3601controls) were included in this meta-analysis.Relative to controls,Alzheimer’s disease patients had a significantly lower global retinal nerve fiber layer thickness(standardized mean difference [SMD]=-0.79,95% confidence intervals [CI]:-1.03 to-0.54,P <0.00001) as well as each quadrant being thinner in Alzheimer’s disease versus controls.Regarding macular paramete rs,values measured by optical coherence tomography were significantly lower in Alzheimer’s disease than controls for macular thickness(pooled SMD:-0.44,95% CI:-0.67 to-0.20,P=0.0003),foveal thickness(pooled SMD=-0.39,95% CI:-0.58 to-0.19,P <0.0001),ganglion cell inner plexiform layer(SMD=-1.26,95% CI:-2.24 to-0.27,P=0.01) and macular volume(pooled SMD=-0.41,95% CI-0.76 to-0.07,P=0.02).Analysis using optical coherence tomography angiography parameters revealed mixed results between Alzheimer’s disease and controls.Superficial vessel density(pooled SMD=-0.42,95% CI:-0.68 to-0.17,P=0.0001) and deep vessel density(pooled SMD=-0.46,95% CI:-0.75 to-0.18,P=0.001) were found to be thinner in Alzheimer’s disease patients whereas the foveal avascular zone(SMD=0.84,95% CI:0.17-1.51,P=0.01) was larger in controls.Vascular density and thickness of various retinal laye rs were decreased in Alzheimer’s disease patients compared to controls.Our results provide evidence for optical coherence tomography technology having the potential to detect retinal and microvascular changes in patients diagnosed with Alzheimer’s disease and aid in monito ring and early diagnosis methods.

Value of optical coherence tomography measurement of macular thickness and optic disc parameters for glaucoma screening in patients with high myopia

BACKGROUND The basic method of glaucoma diagnosis is visual field examination,however,in patients with high myopia,the diagnosis of glaucoma is difficult.AIM To explore the value of optical coherence tomography(OCT)for measuring optic disc parameters and macular thickness as a screening tool for glaucoma in patients with high myopia.METHODS Visual values(contrast sensitivity,color vision,and best-corrected visual acuity)in three groups,patients with high myopia in Group A,patients with high myopia and glaucoma in Group B,and patients with high myopia suspicious for glaucoma in Group C,were compared.Optic disc parameters,retinal nerve fiber layer(RNFL)thickness,and ganglion cell layer(GCC)thickness were measured using OCT technology and used to compare the peri-optic disc vascular density of the patients and generate receiver operator characteristic(ROC)test performance curves of the RNFL and GCC for high myopia and glaucoma.RESULTS Of a total of 98 patients admitted to our hospital from May 2018 to March 2022,totaling 196 eyes in the study,30 patients with 60 eyes were included in Group A,33 patients with 66 eyes were included in Group B,and 35 patients with 70 eyes were included in Group C.Data were processed for Groups A and B to analyze the efficacy of RNFL and GCC measures in distinguishing high myopia from high myopia with glaucoma.The area under the ROC curve was greater than 0.7,indicating an acceptable diagnostic value.CONCLUSION The value of OCT measurement of RNFL and GCC thickness in diagnosing glaucoma in patients with high myopia and suspected glaucoma is worthy of development for clinical use.

Retinal nerve fiber layer thickness changes in obstructive sleep apnea syndrome: one year follow-up results

·AIM: To investigate the retinal nerve fiber layer(RNFL)thickness changes in patients with obstructive sleep apnea syndrome(OSAS) for one year follow-up. To discuss the possibility of detecting tendency of glaucoma in this population by using spectral domain optical coherence tomography(3D-OCT-2000 Spectral domain).·METHODS: After polysomnographic study, all subjects(64 OSAS patients and 40 controls) underwent detailed ophthalmological examination. After these examinations,patients with glaucoma and patients who had ophthalmological and/or systemic disease were excluded from the study.Totally, 20 patients in OSAS group and five patients in controls were excluded from the study in the first examination and follow-up period. The RNFL thickness was assessed with OCT. Forty-four OSAS patients and 35 control subjects were followed up for12 mo. RNFL thickness change and OSAS patients were evaluated for severity of disease by Apnea-Hypopnea Index(AHI).·RESULTS: Forty-four OSAS patients and 35 controls were enrolled in the study. Statistically significance was found between OSAS patients and controls at the 12 thmo.Average RNFL thickness was found to be significantly lower in last measurements in OSAS patients when compared with first measurements and control subjects(P 【0.001, 0.002, respectively). There was a statistically significant correlation among AHI, and RNFL thickness(P 【0.05).·CONCLUSION: The results suggest that the patients with OSAS were related with a proportional decrease in the RNFL thickness. These patients should be followed up regularly for glaucomatous changes. Detecting more RNFL thinning in severe OSAS was important.

Diurnal changes in retinal nerve fiber layer thickness with obstructive sleep apnea/hypopnea syndrome

AIM： To compare the retinal nerve fiber layer （RNFL） thickness in the morning and evening in Thai patients with varying degrees of obstructive sleep apnea/ hypopnea syndrome （OSAHS）. METHODS： In this cross-sectional study, potential OSAHS patients at Siriraj Hospital underwent polysomnography to determine the severity of OSAHS and an eye examination （including best corrected visual acuity, slit-lamp examination, and Goldmann applanation tonometry）. RNFL thickness was recorded once in the morning and once in the evening, using spectral domain optical coherence tomography. Thickness was expressed as an average and given for each quadrant. Patients with ocular or systemic diseases that might affect RNFL thickness were excluded. RESULTS： Forty-one eyes of 41 patients were classified into 40SAHS groups. The average and mean RNFL thickness in most of the four quadrants of the severe OSAHS group trended toward being less than those in the comparable quadrants of the other groups in both the morning and evening. In the moderate OSAHS group, the average RNFL thickness and temporal and superior quadrant thickness in the morning were significantly higher than in the evening （P=0.01, P=0.01, and P=0.03, respectively）. In the severe OSAHS group, the inferior quadrant thickness in the morning was significantly higher than in the evening （P =0.03）. CONCLUSION： The RNFL thickness in the morning was higher than in the evening in moderate OSAHS.

Changes of peripapillary vascular density and its correlation with nerve fiber layer thickness in patients with unilateral retinal vein occlusion

Objective:To observe the changes of peripapillary vascular density(VD)and its correlation with retinal nerve fiber layer(RNFL)thickness in patients with unilateral retinal vein occlusion(RVO)by optical coherence tomography angiography(OCTA).Methods:Prospective case-control study.Thirty-two patients(32 eyes)with RVO diagnosed at the Eye Hospital of China Academy of Chinese Medical Sciences from September 2020 to June 2021 were selected.Another 32 outpatients(32 eyes)with normal ocular examination were selected as the normal control group.Optic disc blood flow imaging was performed in all subjects using the OCTA to measure peripapillary RNFL thickness,peripapillary vessel density,optic disc area,and disc rim area.The correlation between peripapillary vascular density and RNFL,optic disc area and disc rim area in eyes with unilateral RVO was analyzed.Results:Compared with the normal control group,the prevalence of hypertension was higher in the unilateral RVO group,and the difference was statistically significant(P<0.05).Compared with the normal control group,the overall,inferior and temporal RNFL thickness around the optic disc was thinner in patients with unilateral RVO,and the difference was statistically significant(P<005).Compared with the normal control group,the overall VD,internal ring,external ring and inferior VD around the optic disc were slightly decreased in patients with unilateral RVO,and the differences were statistically significant(P<0.05).The results of Pearson correlation analysis indicated that RNFL thickness was positively correlated with peripapillary global VD(r=0.648,P<0.001),RNFL thickness was positively correlated with intrapapillary ring VD(r=0.427,P=0.015),and RNFL thickness was positively correlated with peripapillary VD(r=0.666,P<0.001).Conclusion:The results showed that the RNFL thickness around the optic disc was thinner in patients with unilateral RVO,especially in the inferior and temporal area,and the full area VD around the optic disc was decreased,especially in the internal ring,external ring and inferior area.In patients with unilateral RVO,peripapillary RNFL was positively correlated with peripapillary global,internal ring and external ring VD.

Comparison of retinal nerve fiber layer and macular thickness measurements with Stratus OCT and OPKO/OTI OCT devices in healthy subjects

AIM: To compare retinal nerve fiber layer(RNFL) and macular thickness measurements obtained with the Stratus optical coherence tomography(OCT) and OPKO/OTI OCT devices.METHODS: Included in the study were 59 eyes of 30 participants. All measurements for each eye were done on the same day with both devices. Student’s paired t-tests were used to compare the central macular thickness and RNFL measurements of the Stratus OCT and OPKO/OTI OCT. Pearson correlation was used to assess the relationship between the devices. Coefficient of variation(COV) was calculated to assess intersession repeatability.RESULTS: Using both the Stratus OCT and OPKO/OTI OCT, respectively, the measured mean average RNFL thicknesses were 98.9±11.1 μm and 115.1±9.6 μm(P =0.001),and the measured mean central retinal thicknesses(CRT)were 196.2 ±18.8 μm and 204.5 ±21.1 μm(P 【0.001).Measured by the two devices, the RNFL thickness values were correlated in all quadrants, as were the retinal thickness values except the inferior outer sector. COV for average RNFL and CRT thickness were 2.9% and 4.6%for Stratus OCT, and 2.1% and 4.2% for OPKO/OTI OCT,respectively.CONCLUSION: We found good reproducibility of RNFL and retina thickness measurements for both Stratus OCT and OPKO/OTI OCT devices. However, even though the two OCT systems provided statistically correlated results,the values for both RNFL and macular thickness were statistically different. RNFL and macular thickness measurements with the OPKO/OTI OCT were higher than that of the Stratus OCT; therefore, the two OCT systems cannot be used interchangeably for the measurements of RNFL and macular thickness.

Retinal ganglion cell-inner plexiform and nerve fiber layers in neuromyelitis optica

AIM： To determine the thickness of the retinal ganglion cell-inner plexiform layer（GCIPL） and the retinal nerve fiber layer（RNFL） in patients with neuromyelitis optica（NMO）.METHODS： We conducted a cross-sectional study that included 30 NMO patients with a total of 60 eyes. Based on the presence or absence of optic neuritis（ON）, subjects were divided into either the NMO-ON group（30 eyes） or the NMO-ON contra group（10 eyes）. A detailed ophthalmologic examination was performed for each group; subsequently, the GCIPL and the RNFL were measured using highdefinition optical coherence tomography（OCT）. RESULTS： In the NMO-ON group, the mean GCIPL thickness was 69.28±21.12 μm, the minimum GCIPL thickness was 66.02±10.02 μm, and the RNFL thickness were 109.33±11.23, 110.47±3.10, 64.92±12.71 and 71.21±50.22 μm in the superior, inferior, temporal and nasal quadrants, respectively. In the NMO-ON contra group, the mean GCIPL thickness was 85.12±17.09 μm, the minimum GCIPL thickness was 25.39±25.1 μm, and the RNFL thicknesses were 148.33±23.22, 126.36±23.45, 82.21±22.30 and 83.36±31.28 μm in the superior, inferior, temporal and nasal quadrants, respectively. In the control group, the mean GCIPL thickness was 86.98±22.37 μm, the minimum GCIPL thickness was 85.28±10.75 μm, and the RNFL thicknesses were 150.22±22.73, 154.79±60.23, 82.33±7.01 and 85.62±13.81 μm in the superior, inferior, temporal and nasal quadrants, respectively. The GCIPL and RNFL were thinner in the NMO-ON contra group than in the control group（P〈0.05）; additionally, the RNFL was thinner in the inferior quadrant in the NMO-ON group than in the control group（P〈0.05）. Significant correlations were observed between the GCIPL and RNFL thickness measurements as well as between thickness measurements and the two visual field parameters of mean deviation（MD） and corrected pattern standard deviation（PSD） in the NMO-ON group（P〈0.05）. CONCLUSION： The thickness of the GCIPL and RNFL, as measured using OCT, may indicate optic nerve damage in patients with NMO.

A study of retinal parameters measured by optical coherence tomography in patients with multiple sclerosis

AIM: To investigate the difference of retinal nerve fiber layer (RNFL) thickness and macular fovea thickness/volume between multiple sclerosis (MS) patients and healthy normal individuals using optical coherence tomography (OCT) and assess its association with visual field parameters. METHODS: Thirty consecutive MS patients and 28 healthy controls were recruited in this prospective study. Comprehensive standardized ophthalmic examinations included visual acuity, cycloplegic refraction, intraocular pressure, gonioscopy, visual field, and RNFL thickness and macular fovea thickness/volume detection using Humphrey OCT. Mean values for the thickness of the peripapillary RNFL and macular volume were calculated. Associations between visual field parameters and RNFL thickness/macular volume were analyzed by Pearson correlation analysis. RESULTS: The RNFL thicknesses in each quadrant, the average macular thickness, and the average macular volume in MS patients were all less than those in healthy controls, with statistically significant differences. The RNFL thickness and macular fovea thickness/volume were greater in eyes without optic neuritis than in eyes with optic neuritis. The average visual field parameters had positive correlations with the RNFL thickness and negative correlations with macular parameters in MS patients. CONCLUSION: OCT measurements can effectively identify the nerve changes of MS patients, which provide more data for the diagnosis of MS.

Analysis of retinal vasculature changes in indirect traumatic optic neuropathy using optic coherence tomography angiography

AIM:To assess the retinal vasculature alterations in indirect traumatic optic neuropathy(ITON)patients following craniofacial trauma by optic coherence tomography angiography(OCTA).METHODS:Patients diagnosed of monocular ITON were recruited from August 2016 to May 2020.OCTA was performed using the Angio Vue OCT-A system for two cube scans centered at the optic nerve head and fovea.OCTA data included thicknesses of peripapillary retinal nerve fiber layer(RNFL)and macular ganglion cell complex(GCC),as well as proportion of capillary perfusion and data were analyzed for correlation with post-injury timepoints:within 7,8-30,31-90,and 91-365d.RESULTS:A total of 73 ITON patients were studied.Significant thinning of RNFL and GCC layers and attenuation of microvascular perfusion were observed in ITON eyes as compared to contralateral unaffected eyes(for most of the analyzed sectors and quadrants,P<0.05).Without respect to surgical intervention and vision recovery,the decrease in retinal layer thicknesses and microvascular perfusion was time-dependent,and most significant within three months(P<0.001).CONCLUSION:ITON presents with time-dependent thinning of retinal layers and attenuation of microvasculature,indicating possible degeneration of retinal ganglion cells due to reduced retinal blood supply.

The role of optical coherence tomography in neuro-ophthalmology

Optical coherence tomography(OCT)is an ocular imaging technique that can complement the neuro-ophthalmic assessment,and inform our understanding regarding functional consequences of neuroaxonal injury in the afferent visual pathway.Indeed,OCT has emerged as a surrogate end-point in the diagnosis and follow up of several demyelinating syndromes of the central nervous system(CNS),including optic neuritis(ON)associated with:multiple sclerosis(MS),neuromyelitis optica spectrum disorder(NMOSD),and anti-myelin oligodendrocyte glycoprotein(MOG)antibodies.Recent advancements in enhanced depth imaging(EDI)OCT have distinguished this technique as a new gold standard in the diagnosis of optic disc drusen(ODD).Moreover,OCT may enhance our ability to distinguish cases of papilledema from pseudopapilledema caused by ODD.In the setting of idiopathic intracranial hypertension(IIH),OCT has shown benefit in tracking responses to treatment,with respect to reduced retinal nerve fiber layer(RNFL)measures and morphological changes in the angling of Bruch’s membrane.Longitudinal follow up of OCT measured ganglion cell-inner plexiform layer thickness may be of particular value in managing IIH patients who have secondary optic atrophy.Causes of compressive optic neuropathies may be readily diagnosed with OCT,even in the absence of overt visual field defects.Furthermore,OCT values may offer some prognostic value in predicting post-operative outcomes in these patients.Finally,OCT can be indispensable in differentiating optic neuropathies from retinal diseases in patients presenting with vision loss,and an unrevealing fundus examination.In this review,our over-arching goal is to highlight the potential role of OCT,as an ancillary investigation,in the diagnosis and management of various optic nerve disorders.

Intraocular retinal thickness asymmetry in early stage of primary open angle glaucoma and normal tension glaucoma

AIM： To investigate the intraocular retinal thickness asymmetry of peripapillary retinal nerve fiber layer（pR NFL） and macular layers measured by spectral-domain optical coherence tomography（SD-OCT） in patients with early stage of primary open angle glaucoma（POAG） and normal tension glaucoma（NTG）.METHODS： A total of 117 patients with early stage of glaucoma（54 patients with POAG and 63 patients with NTG） and 32 normal subjects were recruited for the study. The pR NFL thickness, total macular layer（TML） thickness, and isolated inner macular layer（IML） thickness were measured by SD-OCT. Hemisphere TML thickness asymmetry measured by the posterior pole asymmetry scan was evaluated. Thickness differences of pR NFL and IML between superior and inferior quadrants were calculated. Asymmetry indices（AIs） of the p RNFL, TML and isolated IML were also computed. Areas under the receiver-operating characteristic curves（AROCs） were generated to determine the diagnostic capabilities of different parameters. RESULTS： Intraocular p RNFL thickness differences and AIs between the superior and inferior quadrants were significantly different between normal and NTG groups（P=0.009 and P〈0.001, respectively）. Intraocular p RNFL thickness differences and AIs between the temporal-superior and temporal-inferior sectors were also significantly different between normal and NTG groups（P=0.035 and P〈0.001, respectively）. The thickness differences and AIs of TML between superior and inferior hemispheres were significantly different between normal and NTG groups（P=0.001 and P=0.001, respectively） and between normal and POAG groups（P=0.032 and P=0.020, respectively）. The thickness differences and AIs of macular ganglion cell layer（mG CL） between superior and inferior quadrants were significantly different between normal and NTG groups（P=0.013 and P=0.004, respectively）, and between NTG and POAG groups（P=0.015 and P=0.012, respectively）. The thickness difference of TML between superior and inferior hemispheres showed the highest diagnostic capability for early NTG eyes（AROC=0.832）.CONCLUSION： Intraocular retinal thickness asymmetry in pR NFL, TML and mG CL are found in early stage of NTG. Hemisphere TML thickness asymmetry is also found in POAG eyes. Asymmetry analysis of retinal thickness can be an adjunctive modality for early detection of glaucoma.

Macular thickness as a predictor of loss of visual sensitivity in ethambutol-induced optic neuropathy

Ethambutol is a common cause of drug-related optic neuropathy.Prediction of the onset of ethambutol-induced optic neuropathy and consequent drug withdrawal may be an effective method to stop visual loss.Previous studies have shown that structural injury to the optic nerve occurred earlier than the damage to visual function.Therefore,we decided to detect structural biomarkers marking visual field loss in early stage ethambutol-induced optic neuropathy.The thickness of peripapillary retinal nerve fiber layer,macular thickness and visual sensitivity loss would be observed in 11 ethambutol-induced optic neuropathy patients（22 eyes） using optical coherence tomography.Twenty-four healthy age-and sex-matched participants（48 eyes） were used as controls.Results demonstrated that the temporal peripapillary retinal nerve fiber layer thickness and average macular thickness were thinner in patients with ethambutol-induced optic neuropathy compared with healthy controls.The average macular thickness was strongly positively correlated with central visual sensitivity loss（r2=0.878,P=0.000）.These findings suggest that optical coherence tomography can be used to efficiently screen patients.Macular thickness loss could be a potential factor for predicting the onset of ethambutol-induced optic neuropathy.

Pseudo-Glaucoma after Hypertensive Retinopathy

A 35-year-old Japanese woman showed the typical fundus appearance of acute hypertensive retinopathy, including multiple cotton-wool spots, retinal hemorrhages, star exudates, and disc edema bilaterally. Her systemic blood pressure was high (246/158 mmHg). Nephrologists diagnosed her with secondary hypertension due to immunoglobulin A nephropathy. After 2 years, all signs of acute retinopathy resolved and only multiple striated or sectorial darkening of the fundus (retinal nerve fiber layer defects [NFLD]) remained. Computerized analysis of the macular thickness measurement by optical coherence tomography alerted the risk of glaucoma. NFLD is a hallmark of early glaucoma that is more reliable than IOP elevations since normal tension glaucoma is popular in Japan. To differentiate this case from true glaucoma, information regarding her past history is critical for her future ophthalmologists.

OCTA检测青少年不同程度近视患者视网膜神经纤维层厚度和视乳头周围脉络膜毛细血管的微观结构改变

目的利用光学相干断层扫描血管造影术(OCTA)测定青少年不同程度近视眼视网膜神经纤维厚度(RNFL)及视乳头周围脉络膜毛细血管的微结构改变。方法回顾性将2022年1月至2023年1月的惠州市中心人民医院收治的90例5~15岁青少年(共计180只眼睛)作为研究对象,按等效球镜度数(SE)分为正视组(n=30),轻度近视组(n=44),中度近视组(n=56),高度近视组(n=50)。用OCTA测定各组的RNFL、视盘旁萎缩弧β区(PPA-β)及视盘旁萎缩弧α区(PPA-α)面积、PPA-β及PPA-α区微血管丢失(MVD)面积、PPA-β及PPA-α区血流密度值,同时收集各组的SE和眼轴长度(AL)进行比较,用Spearman相关性分析PPA-β区MVD面积与SE、AL、RNFL及PPA-β区面积的相关性。结果4组的SD、AL值比较,差异均有统计学意义(P<0.05),且随着近视程度越重SD、AL值越高。4组的上方、下方、鼻侧及颞侧RNFLT、平均RNFLT比较,差异均有统计学意义(P<0.05);轻度近视组与正视组的上方、下方、鼻侧及颞侧RNFLT、平均RNFLT差异均无统计学意义(P>0.05);高度近视组的上方、下方、颞侧和平均RNFLT均显著低于中度近视组和轻度近视组,差异均有统计学意义(P<0.05)。150只近视眼中有141只(94.00%)的PPA-β区存在MvD。高度近视组PPA-β区的MvD面积、PPA-β面积分别为(0.239±0.106)、(1.104±0.270)mm^(2),均显著高于中度近视组[(0.095±0.041)、(0.612±0.264)mm^(2)]和轻度近视组[(0.071±0.030)、(0.507±0.241)mm^(2)],而PPA-β区血流密度为198.24±95.89,低于中度近视组(349.07±126.32)和轻度近视组(402.63±132.09),差异均有统计学意义(P<0.05)。高度近视组PPA-α区存在MvD占比为56.00%,显著高于中度近视组(26.79%)和轻度近视组(15.91%),差异有统计学意义(P<0.05),3组PPA-α区的MvD面积、PPA-α面积及PPA-α区血流密度差异均无统计学意义(P>0.05)。Spearman相关性分析显示,PPA-β区MvD面积与与SE、RNFLT呈负相关(r=-0.492、-0.574,P<0.05),与AL、PPA-β区面积呈正相关(r=0.480、0.798,P<0.05)。结论PPA-β区MvD是青少年高度近视患者视乳头周围脉络膜毛细血管的微血管改变的重要指标,且与SE、AL、RNFLT和PPA-β区面积相关。