Normative Values of Retinal Nerve Fibre Layer Thickness and Optic Nerve Head Parameters and Their Association with Visual Function in an African Population

NeuroBehcet's-related intracranial hypertension without cerebral venous thrombosis: case report and review of literature

BACKGROUND

We present a rare case of NeuroBehcet's-related intracranial hypertension without cerebral venous thrombosis (NBrIHwCVT), occurring as the first presentation of NeuroBehcet's. In addition, we describe the novel use of subcutaneous tocilizumab for this indication. This is followed by a review of the literature on this topic.

CASE

The patient was a 28-year-old lady of Southern Chinese origin with a known history of Behcet's disease with oral ulcers and ocular findings for which she was on mycophenolate mofetil and adalimumab. She presented with a headache and bilateral disc swelling associated with an intracranial pressure (ICP) of > 40cmH20. There were no structural lesions or cerebral venous thrombosis (CVT) on imaging. Initial lumbar puncture had raised leucocytes and protein. We discuss diagnostic challenges given persistently elevated ICP despite subsequent non-inflammatory cerebrospinal fluid (CSF) profiles and non-response to acetazolamide. She eventually showed a response to immunosuppressant therapy in the form of pulsed methylprednisolone, cyclophosphamide and subsequently subcutaneous tocilizumab, supporting the diagnosis of NBrIHwCVT. Complete normalization of ICP remains challenging. Her disease course was severe, unusual for her ethnicity.

LITERATURE REVIEW

We identified 34 patients (including ours) from 14 publications. We found that the majority of NBrIHwCVT patients were young (average age of 34 years), with a slight female preponderance. Of the 17 cases in the literature with available data on CSF profile, none had raised leucocytes whilst one patient had elevated protein. Patients were generally treated with steroids and occasionally azathioprine, in line with the suspected autoimmune pathophysiology. Of 22 patients with data on outcome, six (27%) were noted to have recurrence of symptoms generally occurring a few months later.

CONCLUSION

As demonstrated by this case, NBrIHwCVT can present with BD with raised ICP even if there is no prior history of NB, central Asian ethnicity, cerebral venous thrombosis or features of inflammation on the CSF. We demonstrated how novel use of Tocilizumab may have a role in the management of NBrIHwCVT. Based on our literature review, patients were more likely to be young, female, display a non-inflammatory CSF picture, be treated with steroids and harbour a possibility of recurrence.

PallorMetrics: Software for Automatically Quantifying Optic Disc Pallor in Fundus Photographs, and Associations With Peripapillary RNFL Thickness

Purpose

We sough to develop an automatic method of quantifying optic disc pallor in fundus photographs and determine associations with peripapillary retinal nerve fiber layer (pRNFL) thickness.

Methods

We used deep learning to segment the optic disc, fovea, and vessels in fundus photographs, and measured pallor. We assessed the relationship between pallor and pRNFL thickness derived from optical coherence tomography scans in 118 participants. Separately, we used images diagnosed by clinical inspection as pale (n = 45) and assessed how measurements compared with healthy controls (n = 46). We also developed automatic rejection thresholds and tested the software for robustness to camera type, image format, and resolution.

Results

We developed software that automatically quantified disc pallor across several zones in fundus photographs. Pallor was associated with pRNFL thickness globally (β = -9.81; standard error [SE] = 3.16; P < 0.05), in the temporal inferior zone (β = -29.78; SE = 8.32; P < 0.01), with the nasal/temporal ratio (β = 0.88; SE = 0.34; P < 0.05), and in the whole disc (β = -8.22; SE = 2.92; P < 0.05). Furthermore, pallor was significantly higher in the patient group. Last, we demonstrate the analysis to be robust to camera type, image format, and resolution.

Conclusions

We developed software that automatically locates and quantifies disc pallor in fundus photographs and found associations between pallor measurements and pRNFL thickness.

Translational Relevance

We think our method will be useful for the identification, monitoring, and progression of diseases characterized by disc pallor and optic atrophy, including glaucoma, compression, and potentially in neurodegenerative disorders.

Racial Differences in Diagnostic Accuracy of Retinal Nerve Fiber Layer Thickness in Primary Open-Angle Glaucoma

Purpose

To evaluate the diagnostic accuracy of retinal nerve fiber layer thickness (RNFLT) by spectral-domain optical coherence tomography (OCT) in primary open-angle glaucoma (POAG) in eyes of African (AD) and European descent (ED).

Design

Comparative diagnostic accuracy analysis by race.

Participants

379 healthy eyes (125 AD and 254 ED) and 442 glaucomatous eyes (226 AD and 216 ED) from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study.

Methods

Spectralis (Heidelberg Engineering GmbH) and Cirrus (Carl Zeiss Meditec) OCT scans were taken within one year from each other.

Main Outcome Measures

Diagnostic accuracy of RNFLT measurements.

Results

Diagnostic accuracy for Spectralis-RNFLT was significantly lower in eyes of AD compared to those of ED (area under the receiver operating curve [AUROC]: 0.85 and 0.91, respectively, P=0.04). Results for Cirrus-RNFLT were similar but did not reach statistical significance (AUROC: 0.86 and 0.90 in AD and ED, respectively, P =0.33). Adjustments for age, central corneal thickness, axial length, disc area, visual field mean deviation, and intraocular pressure yielded similar results.

Conclusions

OCT-RNFLT has lower diagnostic accuracy in eyes of AD compared to those of ED. This finding was generally robust across two OCT instruments and remained after adjustment for many potential confounders. Further studies are needed to explore the potential sources of this difference.

Comparing optic nerve head parameters in two Spanish dog breeds using digital planimetry

The optic discs of dogs exhibit considerable size, shape, and colour variations, depending on the degree of myelination. This variability makes the interpretation of lesions difficult, owing to the lack of reference patterns. This study aimed to compare optic nerve head (ONH) parameters determined by digital planimetry (DP) in two pure-bred dogs, Spanish Greyhound (SG) and Spanish Water Dog (SWD). The vertical and horizontal diameters, area, circularity, and the proportion of the ONH at the tapetal or non-tapetal zone (top height and bottom height) were calculated using image treatment software and compared between breeds. Significant between-breed differences were detected for all parameters, with SWD exhibiting greater height, width, area, top height, and lower circularity of the ONH than SG. Linear regression revealed that age significantly influenced mean disc height (R2 = 0.310; p = 0.0001), mean disc width (R2 = 0.280; p = 0.0001), mean disc area (R2 = 0.281; p = 0.0001), and circularity (R2 = 0.243; p = 0.0001). The multiple regression model significantly predicted mean disc height, width, and area [(S) (R2 = 0.715; p = 0.001), (R2 = 0.742; p = 0.001), and (S) (R2 = 0.736; p = 0.001), respectively], based on age and breed. Excellent concordance was observed between the measurements of experienced and novice researchers, and there were no differences between the parameters measured by the researcher and those obtained by the software. Planimetric ONH measurements can be easily performed by novice operators using a portable fundus camera and digital computer software. These results may be of considerable clinical value, but further studies are required because of the great variability of the ONH in dogs.

Clinical Profile of Primary Open-angle Glaucoma Patients at an Eye Center in Nigeria

Aim

Globally, one of the leading causes of preventable blindness is primary open-angle glaucoma (POAG). The study assessed the clinical presentations of POAG patients attending an eye center in Abuja, Nigeria.

Materials and methods

Records of 188 eyes, collected from 94 patients diagnosed with POAG for a period of 1 year at the eye center, were reviewed. Clinical records, including age, gender, visual acuity (VA), central cornea thickness (CCT), intraocular pressure (IOP), cup-to-disk ratios, and retinal nerve fiber layer (RNFL) thickness of the participants, were extracted and analyzed.

Results

The majority of the participants were males (56.4%) and adults (57.4%), most of whom had normal VA (>70% in each eye). Our analysis revealed normal average estimates of RNFL thickness, IOP, and CCT among the participants. Females had thicker RNFL compared to males (p = 0.02). Although CCT decreased with age (r = -0.28, p = 0.005), there was no such link between IOP and CCT (r = 0.09, p = 0.38).

Conclusion

Central cornea thickness (CCT), RNFL thickness, and IOP in isolation should not be used as early indicators for POAG; rather, a combination of these and other indices is recommended. Early detection through active screening and treatment in the community for at-risk groups is highly advised.

How to cite this article

Ezinne NE, Kwarteng MA, Ekemiri KK, et al. Clinical Profile of Primary Open-angle Glaucoma Patients at an Eye Center in Nigeria. J Curr Glaucoma Pract 2023;17(3):113-117.

Optic Nerve Head Parameters in Saudi Male Young Adults Using Swept-source Optical Coherence Tomography

Purpose

To assess the optic nerve head (ONH) parameters in normal male Saudi eyes using swept-source optical coherence tomography (SS-OCT).

Materials and methods

The study included 86 healthy men with a mean age of 23.6 ± 4.82 years. The metrics collected using SS-OCT from each individual was disk area (DA), rim area (RA), cup volume (CV), linear cup-disk ratio (LCDR), vertical cup-disk ratio (VCDR), and total retinal nerve fiber layer (RNFL) thickness, superior RNFL thickness, and inferior RNFL thickness. All the metrics were correlated with the DA. The right eye data were used for the correlation analysis.

Results

The mean DA in OD was 1.78 mm2 (range 1.09-2.70 mm2). The mean RA was 1.28 mm2 (range 0.72-2.47 mm2). The DA showed a significant positive correlation (p < 0.05) with RA, cup area (CA), CV, VCDR, LCDR, and total RNFL thickness.

Conclusion

For the first time, using sweeping source OCT (DRI OCT Triton, Topcon Corporation), a normative database of ONH parameters was made accessible to the Saudi male population. While assessing the optic disk for progressive optic neuropathies like glaucoma, disk size should be taken into consideration since the optic DA affects ONH topography, especially in Saudi eyes.

How to cite this article

Challa NK. Optic Nerve Head Parameters in Saudi Male Young Adults Using Swept-source Optical Coherence Tomography. J Curr Glaucoma Pract 2023;17(2):58-62.

Predictors of Retinal Nerve Fiber Layer Parameters Following Scleral Buckling Surgery in Primary Rhegmatogenous Retinal Detachment

Objective: This study aimed to examine predictors of retinal nerve fiber layer (RNFL) parameters following scleral buckling (SB) surgery for primary rhegmatogenous retinal detachment (RRD) and to determine the influence of the magnitude of change in qualitative and quantitative parameters on RNFL.

Methods: In an observational prospective study, 40 subjects who underwent successful retinal reattachment with SB surgery done within one month of RRD were evaluated for the parameters of best-corrected visual acuity (BCVA), refractive error, intraocular pressure (IOP), axial length (AL), anterior chamber depth (ACD), angle opening distance (AOD 500 and AOD 750), trabecular iris surface area (TISA 500 and TISA 750), visual fields, and ganglion cell count (GCC) and RNFL before and three months after SB. We additionally noted qualitative factors like extent, location, and type of buckle; phakic status; and grade of proliferative vitreoretinopathy in the affected eye. The change in value of quantitative parameters was found. The influence of baseline values and magnitude of change of quantitative and qualitative parameters on average RNFL thickness and magnitude of change of RNFL thickness after SB was found.

Results: Post-SB, average RNFL thickness reduced from 108.58±20.38 microns to 103.73±17.98 microns (p =0.042). The baseline temporal upper (TU), temporal lower (TL), and nasal lower (NL) RNFL thickness (p=0.01, p=0.02, p=0.01, respectively) and total deviation (TD) values of visual fields (p=0.01) correlated positively while baseline GCC gross loss of volume (p=0.01) correlated negatively with post-operative RNFL thickness. The TU, TL, and NL RNFL thickness (p=0.04, p=0.01, p=0.01, respectively) and average GCC (p=0.04) correlated negatively with the magnitude of change in RNFL. The magnitude of change in baseline parameters after surgery was correlated with the magnitude of change in average RNFL thickness. It was noticed that change in AL (p<0.01), TISA 500 (p=0.02), TISA 750 (p<0.01), GCC focal loss of volume (p=0.02), and temporal RNFL thickness (p<0.01) correlated positively while the change in refractive error correlated negatively (p=0.04). Except for the grade of proliferative vitreoretinopathy (PVR) (p=0.04), none of the qualitative parameters, including extent, type, and location of the buckle; and phakic status, had a significant association with post-operative average RNFL thickness or magnitude of its change.

Conclusions: The predictors of average RNFL thickness following SB include AL; myopic shift; TISA; visual fields TD; average, TU, TL, and NL RNFL thickness; average GCC, gross and focal loss of volume; and grade of PVR. So an early surgery to prevent preoperative ganglion cell and RNFL loss and progression of PVR is recommended.

Comparison of imaging parameters between OCT, GDx and HRT in the Northern Finland birth cohort eye study

PURPOSE

The purpose of the study was to assess and compare the optic nerve head (ONH) and retinal nerve fibre layer (RNFL) parameters and image quality parameters obtained by Cirrus HD-OCT, GDxECC and HRT3 in a population-based screening study.

METHODS

This analysis examined 2566 subjects taking part in the Northern Finland Birth Cohort Eye study. Images with spectral domain OCT (Cirrus HD-OCT 4000), scanning laser ophthalmoscopy (HRT3) and scanning laser polarimetry (GDxECC) were obtained from each subject. The correlation of average and regional parameters of RNFL and ONH between devices was evaluated.

RESULTS

The RNFL thickness was 90.9 µm when measured with OCT, 24.6 µm with HRT and 48.1 µm with GDx. There was a high correlation between the disc and cup measurements with the HRT and OCT and the RNFL thickness of the OCT and GDx (r > 0.5). A statistically significant correlation was found between RNFL measurements of the HRT and OCT in the superior, temporal and inferior quadrants. Optical coherence tomography (OCT) signal strength correlated with the image quality parameters of the HRT and GDx. The percentage of good quality images was the lowest with the GDx.

CONCLUSION

The RNFL thickness in Northern Finland birth cohort was at a lower level compared to other studies. The study confirms the difference in measuring ONH parameters between the imaging devices. However, significant correlations between devices were found in the cup volume and cup disc area ratio parameters of the OCT and HRT. The correlations between image quality parameters and glaucoma detection parameters were relatively low.

Clinical and sociodemographic characteristics of glaucoma patients at a tertiary referral facility in Zimbabwe

Purpose

To evaluate the clinical and socio-demographic profile of patients living with glaucoma and receiving care in a tertiary eye center in Zimbabwe.

Method

A hospital-based retrospective study of clinical records of glaucoma patients from January 2014 to December 2018. The study involved collating demographic information of patients, visual acuities, (VA) intraocular pressure, (IOP), cup-to-disc ratios, (CDRs), average retinal nerve fibers thickness, (RNFL), cup volume, cup-to-disc area, vertical cup-to-disc ratio, (VCDR), rim area, disc area, glaucoma hemifield test, visual field indices and the management of glaucoma.

Results

Nine thousand one hundred and eighty-five (9,185) folders were retrieved. Out of these, 432 (4.7%) qualified for the study and were analyzed. There were 267 (61.8%) males and 165 (38.2%) females. The mean age (± Standard deviation, SD) of the patients was 62.66 ± 15.94 years, (range 10 - 110 years). The means visual acuity (VA): OD =1.30 ± 1.06 Logarithm of the Minimum Angle of Resolution, (logMAR), OS = 1.33 ± 1.06 logMAR; IOP: OD = 29.51 ± 12.89 mmHg, OS: 29.17 ± 12.59 mmHg; CDRs: OD = 0.91 ± 0.14 D, OS = 0.92 ± 0.14 D; and the average RNFL thickness was 72.76 ± 18.26 µm and 71.24 ± 23.17 µm in the right and left eye respectively. The mainstay of treatment was medication only.

Conclusion

There were more males than females receiving glaucoma care at the tertiary level. Glaucoma cases included juveniles but the mean age was mostly the elderly. It was characterized by high IOPs, large CDRs, and thin RNFL suggestive of late presentation.

Epidemiology and clinical presentation of glaucoma in a referral facility in Ghana: Any lessons for public health intervention?

The purpose of this study was to evaluate the epidemiological and clinical profile of patients living with glaucoma and receiving care in a tertiary eye center in Ghana. This was a hospital-based retrospective study of clinical records of glaucoma patients from January 2010 to December 2019. The study involved collating demographic information of patients, clinical presentation, and the management of glaucoma. A total of nineteen thousand (19,000) charts were retrieved from the eye center's archives. Out of these, 660 (3.5%) records of patients qualified for the study and were analyzed. There were 398 (60.3%) males and 262 (39.7%) females. Their ages ranged from 9 to 86 years (mean age = 47.30; SD ± 16.86 years). The averages of ocular parameters of 1,320 eyes (660 patients) were visual acuity = 0.26 ± 0.55 logMAR; intraocular pressure: 17.31 ± 6.11 mmHg; cup-to-disc ratios: 0.67 ± 0.17 D; and the average retinal nerve fibers thickness was 95.03 ± 21.74 μm. The mainstay of treatment was the sole use of medication. Males were the major group receiving glaucoma care at the tertiary level. Glaucoma cases included juveniles but the mean age suggests most were of adult-onset. Socio-demographic characteristics affected the diagnosis and management of glaucoma among patients receiving care at a referral center. Public health, stakeholders, and policymakers' interventions can help identify individuals with glaucoma.