Retinal Nerve Fiber Layer Assessment Research Articles

Assessment of RNFL and macular changes in the eye related to multiple substance use using OCT

Substance use is a chronic and recurrent public healthcare concern increasing in the world, causing negative outcomes. Two or more substance use is common among people who have substance use disorders and who receive treatment. For this reason, the present study aimed to measure Retinal Nerve Fiber Layer (RNFL), Mean Macular Thickness (MMT), Central Macular Thickness (CMT) in patients who have Multiple substance use disorder (MSUD) using Optical Coherence Tomography (OCT), considering that it will contribute to the literature. Among the inpatients who were rehabilitated in Elazig Mental Hospital Alcohol and Substance Addiction Treatment Center, 75 people who were diagnosed with MSUD according to DSM-5 and met the criteria, and 51 control groups were included in the study. RNFL, MMT and CMT measurements of both eyes of all participants were made by using the OCT. Total RNFL measurement were significantly thicker than the control group (p < 0.001). MMT and CMT of the eyes of the patient were thinner than the control group (p = 0.009, p < 0.001). The findings provide important contributions to the literature data and in light of these findings, it can be recommended to consider visual findings and possible neurodegeneration when evaluating patients in the addiction group and planning their treatment.

Optic nerve head and retinal nerve fiber layer changes by spectral domain optical coherence tomography in glaucoma suspects at tertiary care hospital

Introduction: Glaucoma is a progressive optic neuropathy characterized by functional loss or optic nerve dysfunction which is one of the leading causes of irreversible but preventable blindness. The aim of the study was to determine which of the retinal nerve fiber layer and optic nerve head parameters are reliable markers of optic nerve damage in glaucoma suspects. Methods: Observational cross-sectional study of 250 patient’s including147 glaucoma suspect eyes, 103 normal eyes. All subjects underwent complete eye examination and imaging with the spectral domain optical coherence tomography (SD-OCT) cirrus-TM OCT (Carl Zeiss Meditec, Dublin, CA). Retinal nerve fiber layer (RNFL) and optic nerve head (ONH) OCT protocols were used to evaluate all study participants. The main outcome measures were the difference in OCT parameters among groups. Results: Study shows statistically significant difference in the average RNFL thickness, superior, nasal, inferior, temporal quadrants, rim area, cup volume, average cup to disc ratio (CDR), vertical CDR with P value &lt;0.001 between the two groups. Average CDR, vertical CDR and cup volume had significantly greater AROC values (ROC: 0.99, 0.98, 0.95) than RNFL parameters for discriminating glaucoma suspects from normal eyes. Conclusion: Assessment of RNFL, macular and ONH damage with SD-OCT has been proven useful for diagnosing the disease at different levels of severity, as well as for quantifying risk in glaucoma suspects. In our study ONH measurements, as provided by the SD OCT, have more diagnostic value than RNFL parameters in the diagnosis of glaucoma suspects from normal. Keywords: glaucoma suspects; optic nerve head; retinal nerve fiber layer; optical coherence tomography

Ocular toxicity of daily anti-tubercular treatment regimen: A prospective observational study

Context: India carries a significant burden of TB which is the commonest cause of infectious disease-related mortality. Anti-tubercular drugs can cause serious ocular toxic effects. Optical coherence tomography (OCT) can be used as a valuable tool in the quantitative analysis of anti-tubercular treatment (ATT)-induced toxic optic neuropathy. Aims: To study the changes in visual parameters in patients on ATT and to analyze the OCT changes in patients by taking measurements once before initiation of treatment and once during ongoing treatment (between three and six months). Settings and Design: Tertiary care center, Prospective observational study. Methods and Material: A prospective observational study was conducted in 140 eyes of 70 subjects undergoing ATT as per the latest RNTCP guidelines where the following determinants were examined, and the corresponding values were taken once before initiation of treatment and once during ongoing treatment (between three and six months) and results were analyzed. Around 90% of the subjects were examined at the end fourth month. Visual acuity was taken using the Log Mar chart, color vision using Ishihara’s chart, and slit lamp examination and fundus evaluation using a 90 D lens. OCT was done and average nasal, temporal, superior, and inferior quadrant retinal nerve fiber layer (RNFL) measurements were taken. Perimetry was also done; however, findings were not included in this study. Statistical Analysis Used: Frequency and percentage were applied to study the changes in visual parameters in patients on ATT. A paired t-test was applied for numerical variables to analyze the OCT changes in patients undergoing ATT. A P value &lt; 0.05 was considered statistically significant. Results: Despite a near-normal appearance of the fundus on ophthalmoscopy, OCT clearly demonstrated and quantified the loss of retinal nerve fibers. Statistically significant RNFL thinning (P value &lt; 0.001) was noted in the superior, temporal, and inferior quadrants and least in the nasal quadrant (P = 0.005). Significant deterioration in visual acuity was observed following three months of ATT (P = 0.001). Red-green color vision abnormalities were detected in 14 out of 140 eyes (10%). Conclusions: RNFL thickness was reduced on OCT. RNFL thickness quantification and assessment of other visual parameters especially color vision help in the early diagnosis of ocular toxic effects of ATT. Hence, awareness and active screening are imperative in preventing visual impairment and blindness.

Depth-resolved extraction of optical attenuation for glaucoma assessment in clinical settings: a pilot study.

We assessed the ability of the optical attenuation coefficient (AC) to detect early-stage glaucoma with two AC estimation algorithms: retinal layer intensity ratio (LIR) and depth-resolved confocal (DRC). We also introduced new depth-dependent AC parameters for retinal nerve fiber layer assessment. Optical coherence tomography B-scans were collected from 44 eyes of age-similar participants with eye health ranging from healthy to severe glaucoma, including glaucoma suspect patients. Mean AC values estimated from the DRC method are comparable to ratio-extracted values (p > 0.5 for all study groups), and the depth-dependent ACDRC parameters enhance the utility of the AC for detection of early-stage glaucoma.

Impact of Epiretinal Membrane on Optical Coherence Tomography Tools Used for Monitoring Glaucoma.

Background: Retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) measurements can be influenced by many factors including the presence of concomitant retinal diseases. The aim of this study it to assess the impact of epiretinal membrane (ERM) on RNFL and GCL assessment using optical coherence tomography (OCT). Methods: GCL, peripapillary RNFL (pRNFL), and Bruch’s Membrane Opening Minimum Rim Width (BMO-MRW) thicknesses were analysed using an SD-OCT (Spectralis OCT) in eyes with idiopathic ERM and compared with a control group. Results: 161 eyes were included, 73 eyes in the control group and 88 eyes with idiopathic ERM. The pRNFL analysis revealed a statistically significant difference between the two groups in overall and temporal sector thicknesses. For GCL thickness report, the percentage of scans in which the GCL was erroneously segmented by automatic segmentation was assessed for each eye. A statistically significant difference was found in all sectors (p < 0.001), with the exception of external nasal sector. A statistically significant difference (p < 0.001) in the GCL total volume report was found in ERM group compared to the control group. For MRW at BMO analysis, there was no statistically significant difference in MRW thickness in any sector. Conclusion: In eyes with ERM, the GCL and pRNFL analysis seemed affected by the morphological retinal layers’ modification. MRW-BMO did not appear to be directly affected by the presence of ERM.

Reduced Corneal Sensitivity With Neuronal Degeneration is a Novel Clinical Feature in Wolfram Syndrome

To evaluate corneal sensitivity and corneal nerve morphology among patients with Wolfram syndrome (WFS). An observational clinical case series with confirmatory experiments. We included a group of 12 patients with biallelic mutations in the WFS1 gene and a control group composed of 30 individuals with type 1 diabetes (T1D). All participants (n=42) underwent a complete ophthalmic examination, esthesiometry, and retinal nerve fiber layer assessment using optical coherence tomography. Morphologic assessment of corneal neuropathy by in vivo corneal confocal microscopy was conducted in 11 patients with WFS (both eyes) and 1 WFS patient (1 eye) as well as in 24 patients with T1D (both eyes in 6 patients and 1 eye in 18 patients). Additionally, corneas from Wfs1KO mice and their wild-type littermates were subjected to laser scanning confocal microscopy. Corneal sensitivity was significantly reduced in patients with WFS compared with patients with T1D (4.50 cm [interquartile range, 3.50-5.50 cm] vs 6.00 cm [interquartile range, 6.00-6.00 cm]; P < 10-5). Additionally, corneal nerve fiber and branch density as well as nerve fiber length were low among patients with WFS. Corneal sensitivity correlated with macular average thickness (R=0.6928; P=.039) and best-corrected visual acuity (R=-0.61; P=.002) in the WFS group. Similarly, Wfs1 knockout mice also presented corneal neurodegeneration changes when corneal nerve fiber density and length were measured using laser scanning confocal microscopy. Decreased corneal sensitivity and corneal nerve degeneration are observed in WFS. Corneal sensitivity is linked with the degree of disease progression as measured by visual acuity and retinal thinning.

Retinal Nerve Fibre Layer Assessment in Glaucoma and Glaucoma Suspect by Optical Coherence Tomography (OCT)

Abstract Background Glaucoma is a progressive optic neuropathy characterized by structural changes in the optic nerve head, retinal nerve fiber layer (RNFL) defect, and accompanying visual field damage (VFD). In glaucoma management, detecting progression is essential in both early and late stages of the disease. In patients with an established diagnosis of glaucoma, evidence of progression will influence a clinician’s decision whether to modify glaucoma therapy. In patients who are suspected of having the disease, progression detection can confirm the diagnosis, and help decide how to manage the patient. Although standard automated perimetry has been the most commonly used test to monitor glaucomatous progression, evidence suggests that in some eyes substantial structural damage can be detected before the development of clinically detectable VFD. Objective To compare retinal nerve fibre layer thickness between glaucoma and glaucoma suspects. Methods We conducted our cross sectional comparative study on Forty eight eyes from patients recruited from Ain Shams University Hospitals, Ophthalmology Department during the period from February 2019 to December 2019. The Forty eight eyes were recruited in this study and divided into 2 groups. Group A- (Twenty-four eyes with moderate open angle glaucoma) and Group B- (Twenty four eyes with criteria of glaucoma suspects). Results There was highly Significant difference as regards OCT parameters of the patients (p &amp;lt; 0.001 for all). As the mean value of Cup/disc ratio was lower in Glaucoma Suspected cases, while Total RNFL, RNFL Superior and RNFL Inferior was higher in Glaucoma Suspected cases than patients with Moderate glaucoma. This study showed that; by using ROC-curve analysis, cup to disc ratio (CDR) at a cutoff point (&amp;gt;0.59) detected patients with glaucoma, with excellent accuracy, sensitivity= 95% and specificity= 100%. Also, by using ROC-curve analysis, superior RNFL at a cutoff point (≤116) detected patients with glaucoma, with fair accuracy, sensitivity= 66% and specificity= 91%. While inferior RNFL at a cutoff point (≤113) detected patients with glaucoma, with good accuracy, sensitivity= 70% and specificity= 95%. Conclusion In conclusion, structural progression measured using SD OCT was associated with functional progression shown in VF loss in glaucoma suspect or preperimetric glaucoma eyes and in glaucomatous eyes. Average, inferior and superior RNFL attenuations were the most important risk factors for visual field progression.

Pediatric normative Retinal nerve fiber layer thickness in south Indian population

To study the retinal nerve fiber layer (RNFL) thickness in pediatric age group and its correlation with age, gender, refractive error and axial length Prospective observational study of 200 eyes of 100 children aged between 5-18 years presenting to the ophthalmic department. All children underwent detailed ophthalmic evaluation and SD OCT examination for RNFL thickness, Standard RNFL assessment protocol was used. Mean RNFL thickness in micrometers along the whole circle circumference, four quadrants, 12’o clock hours were obtained. RNFL measurements included average/full circle thickness — RNFL-FC (360ºmeasure), temporal quadrant thickness, RNFL-T, superior quadrant thickness, RNFL-S, nasal quadrant thickness, RNFL-N, inferior quadrant thickness, RNFL-I. Mean age was 13.3 ± 2.4 years. The refractive error in spherical equivalent was -0.28 ± 0.91 dioptre (SE). The mean axial length was 23.1 ± 0.7mm. The mean global RNFL thickness (RNFL-FC) was 97.0 ± 8.8mm (range 79.4 -114.6). RNFL thickness was maximum in the inferior quadrant (RNFL-I) 126 ± 13.7mm followed in order by superior (RNFL-S) 126 ± 16.3mm, nasal (RNFL-N) 70.5 ± 12.3mm and temporal (RNFL-T) 63.4 ± 9.2mm, in both the sexes. For every increase in one diopter of spherical equivalent of refractive error the mean RNFL increased by 3.77 microns and there was a reduction in mean RNFL thickness by 4.86 micron for every 1mm increase in axial length. RNFL varied minimally with gender. Positive correlation was seen with refractive error while inverse or negative correlation was seen with axial length and age. RNFL measurements could serve as reference for further studies on pediatric glaucoma or other optic nerve head pathologies.

Ocular side effects in tuberculosis patients receiving direct observed therapy containing ethambutol

Background: India is among the largest countries to implement the revised national tuberculosis (TB) control program (RNTCP). Ocular toxicity of ethambutol has been known since 1962. It can be halted with early detection and cessation of the contributing drug. Aims and Objectives: This study aims to detect early ocular toxicity of ethambutol in TB patients under directly observed treatment strategy (DOTS). Materials and Methods: This was a prospective cross-sectional study of 30 patients getting AKT including ethambutol along with isoniazid, rifampicin, and pyrazinamide under RNTCP‑DOTS center at a tertiary care hospital. The detailed history, best-corrected visual acuity (BCVA), color vision, fundus examination, visual field, retinal nerve fiber layer (RNFL) thickness, and central subfield macular thickness were carried out in all patients pretreatment and then at the 2nd month of treatment. Results: The mean age of patient was 44.87 years. Reduced visual acuity from the baseline was noted at the second in 23.33% of the right eyes (P = 0.01) and 30% of the left eyes (P < 0.01). Mean temporal RNFL thickness was significantly reduced from baseline after 2 months of treatment (P = 0.046). No significant difference was observed with color vision and visual fields pre- and post-treatment. Conclusion: The assessment of BCVA, color vision, visual field, RNFL, and macular thickness is essential at baseline and thereafter at frequent intervals to detect early ethambutol toxicity and probable reversible visual loss.

The Effect of Anti-Tubercular Drugs on Retinal Nerve Fiber Layer Thickness Using Optical Coherence Tomography

Purpose: To study the effect of anti-tubercular drugs on retinal nerve fiber layer (RNFL) thickness using optical coherence tomography.&#x0D; Methods: The study was done in thirty patients newly diagnosed with pulmonary tuberculosis which were given anti-tubercular treatment (isoniazid, rifampicin, ethambutol and pyrazinamide ) at DOTS centre of K. N. TB and Chest hospital (Dr. S.N M C.) Jodhpur. Visual function tests (visual acuity, contrast sensitivity, color vision) and OCT assessment of RNFL done before initiation of treatment and after two month of treatment.&#x0D; Results: After two months, RNFL thinning was present in 3 eyes out of total 60 eyes in temporal and superior quadrant.&#x0D; Conclusion: The study revealed that the first line antitubercular drug Ethambutol causes RNFL thinning within two months of initiation of drug in the recomonded dose. In the initial stage of optic nerve toxicity, there are no clinically significant changes seen on posterior segment ophthalmoscopic examination and fundus photography.OCT can find out the retinal nerve fiber layer thinning even if there are minute changes.

Can Treatment With Citicoline Eyedrops Reduce Progression in Glaucoma? The Results of a Randomized Placebo-controlled Clinical Trial.

Precis:Citicoline eyedrops in patients with progressing glaucoma.Purpose:This study aimed to test whether the additional therapy with citicoline eyedrops to intraocular pressure (IOP)-lowering treatment could slow glaucoma progression in patients with worsening of damage and IOP 18 mm Hg or less.Design:This was a randomized, double-masked, placebo-controlled, multicenter 3-year study.Outcomes:The outcomes studied were difference in the visual field (mean deviation, MD, of 24-2; MD of 10-2) rates of progression and difference in retinal nerve fiber layer (RNFL) thickness change between the 2 study groups at 3 years.Methods:Patients with mild to moderate open-angle glaucoma (OAG) showing damage progression of at least −0.5 dB/y in the 2 years before enrollment despite IOP ≤18 mm Hg were randomized to receive citicoline eyedrops or placebo 3 times daily for 3 years. Patients were followed every 3 months and underwent a visual field examination with 24-2 and 10-2 strategies and RNFL assessment. Analysis of variance and linear models were used to test the differences between groups.Results:Eighty patients were randomized in the trial. The mean 3-year rates of progression were −1.03 (2.14) dB in the citicoline group and −1.92 (2.23) dB in the placebo group (P=0.07) for 24-2 MD and −0.41 (3.45) dB in the citicoline group and −2.22 (3.63) dB in the placebo group (P=0.02) for 10-2 MD. On average, patients receiving citicoline eyedrops lost 1.86 μm of RNFL in 3 years, versus 2.99 μm in the placebo group (P=0.02).Conclusions:Additional treatment with citicoline eyedrops to IOP-lowering treatment might reduce disease progression in patients with progressing glaucoma despite IOP ≤18 mm Hg.

Prevalence of Unknown Ocular Hypertension, Glaucoma Suspects, and Glaucoma in Patients Seen in an Ophthalmology Center in France

Introduction: The rate of unknown glaucoma is around 50% in industrialized countries. The purpose of our study was to estimate the prevalence of unknown cases of ocular hypertension, glaucoma suspects, and glaucoma in patients consulting for refractive disorders in France. Methods: A retrospective study in the Point Vision ophthalmology center was led in Toulouse, France. All participants consulting for refractive disorders between June 2015 and June 2017 in the ophthalmology center were included. The cases were identified by the assessment of intraocular pressure, optic nerve head structure, and visual field. Ocular hypertension was defined as an intraocular pressure >21 mm Hg. Glaucoma was defined as the association of a glaucomatous papilla and two successive pathological visual fields. Glaucoma suspect was defined as the association of a glaucomatous papilla without visual field defect. The primary endpoint was the prevalence of unknown ocular hypertension, glaucoma suspects, and glaucoma in patients seen in an ophthalmology center. Results: A total of 66,068 patients (mean age = 37 years) consulted for a refraction visual assessment during the study period. Among them, 234 had a visual field and a retinal nerve fiber layer assessment for ocular hypertension and/or suspicious papilla. The prevalence of unknown cases of ocular hypertension, glaucoma suspect, and glaucoma was 2.6, 0.8, and 0.5 per 1,000 consultants, respectively. Median age at diagnosis of ocular hypertension, glaucoma suspect, and glaucoma was 52, 53, and 65 years, respectively. Conclusion: The present study highlights the importance of glaucoma screening in people over 40 years old with the measurement of intraocular pressure and an optic nerve head assessment.

Retinal Nerve Fiber Layer Thickness and Higher Relapse Frequency May Predict Poor Recovery after Optic Neuritis in MS Patients.

Optic neuritis (ON) is a common manifestation of multiple sclerosis (MS). Aiming to evaluate the retinal nerve fiber layer (RNFL) with optical coherence tomography (OCT), patients with relapsing-remitting (RR) MS experiencing ON were consecutively enrolled. RNFL, ganglion cell layer (GCL), foveal thickness, and macular volume were evaluated in both the ON and unaffected (nON) eye within six days from the relapse onset (T0) and after six months (T1). Ninety patients were enrolled. At T0, ON eyes showed a significantly increased RNFL when compared to the nON eyes (129.1 ± 19.5 vs. 100.5 ± 10.1, p < 0.001). At T1 versus T0, the ON eyes showed a thinner RNFL (129.1 ± 19.5 vs. 91.6 ± 20.2, p < 0.001) and a significantly decreased GCL (80.4 ± 8.8 vs. 73.8 ± 11.6; p < 0.005). No differences were found in the nON group in retinal parameters between T0 and T1. A multivariate logistic regression analysis showed that a higher number of relapses (not ON) and a greater swelling of RNFL at T0 were associated with poor recovery. The assessment of RNFL through OCT during and after ON could be used to predict persistent visual disability.

Has Spectral-Domain Optical Coherence Tomography Retinal Nerve Fiber Layer Assessment Become the Method of Choice for Glaucoma Evaluation in Clinical Practice?

AIM:The aim of the study was to assess the role of spectral-domain optical coherence tomography (SD-OCT) as a method of choice for early glaucoma diagnosis in glaucoma suspects.DESIGN:This was a retrospective cross-sectional study.MATERIALS AND METHODS:After a comprehensive ophthalmic examination and visual field analysis, 20 patients were included in each of the three groups: Normal group, possible glaucoma, definitive glaucoma, respectively. The optic nerve head (ONH) and peripapillary retinal nerve fiber layer parameters of participants were analyzed using SD-OCT optic disc cube protocol scans. Data was analyzed using one.way analysis of variance test.RESULTS:ONH RNFL defects in possible glaucoma patients were frequently found in superior, inferior, and temporal quadrants.CONCLUSION:Diagnostic capability of SD-OCT parameters for detection of structural changes in the ONH and retinal nerve fiber layer differed in three groups significantly. Hence, using SD-OCT has become an imperative and quick way of timely diagnosis of glaucoma in private practice.

The assessment of structural changes on optic nerve head and macula in primary open angle glaucoma and ocular hypertension

To assess morphological changes in macula, retinal nerve fiber layer (RNFL) and optic nevre head (ONH) of cases with primary open angle glaucoma (POAG) and ocular hypertension (OH) with spectral domain optic coherence tomography (OCT). This study included 109 eyes from 62 POAG patients, 50 eyes from 30 OH patients, and 101 eyes from 53 healthy volunteers. Data gained by OCT were compared with perimetry indexes. ONH, RNFL and macula analysis were performed for all subjects. Rim area, disc area, average cup/disc (C/D) ratio, vertical C/D ratio, cup volume data were recorded during ONH analysis. Average RNFL thickness and the thickness of four quadrants (superior, inferior, nasal and temporal) was established in microns. In total, nine macular quadrants involving the foveal region mentioned in the Early Treatment Diabetic Treatment Study (ETDRS) template were measured, and average macular thickness and macular volume data were recorded during macula analysis. Differences between groups were evaluated with the one-way ANOVA test. Tukey's multiple comparison test was performed to detect difference between groups. Receiver-operating characteristic (ROC) analysis was done for early stage POAG patients to establish sensitivity and specificity of chosen parameters in early stage POAG. Area under the receiver operating characteristic (AUROC) values were calculated to compare ROC areas. Statistically significant differences were found in all ONH parameters, except optic disc area. Neuroretinal rim area was identified as the parameter with the highest difference between groups (F=21.72, P<0.05). The highest correlation between ONH parameters and perimetry was observed at neuroretinal rim region (r=0.487). Inferior RNFL thickness was established as the parameter with the highest difference between groups among RNFL parameters. In the mean of all glaucoma patients, the highest correlation between data handled with OCT and mean deviation was observed in RNFL thickness. Average macular thickness was detected as the parameter with the highest difference between groups among macular parameters. The highest correlation between macula parameters and perimetry indexes was observed between average macular thickness and perimetry indexes (r=0.514). Although the assessment of ONH and the analysis of macular thickness are important in diagnosis and treatment, RNFL assessment is the most valuable parameter.

Optical coherence tomography retinal nerve fiber layer analysis in eyes with long axial lengths.

PurposeTo evaluate the relationship between axial length (AL) and retinal nerve fiber layer (RNFL) profile and to characterize differences in optical coherence tomography RNFL of myopic glaucomatous eyes compared to nonglaucomatous eyes.MethodsRetrospective chart review of 170 eyes of 89 subjects with optical biometry and optical coherence tomography RNFL assessment was conducted.ResultsTemporal RNFL thickness showed no association with AL in either glaucomatous or nonglaucomatous eyes. Nasal thinning was most strongly associated with glaucoma in myopic eyes. Both myopic glaucomatous and nonglaucomatous eyes had a mean RNFL thickness of 16–22 µm thinner than mean RNFL thickness of normal AL eyes.ConclusionAn average of 16–22 µm thinning of RNFL compared to nomogram can be tolerated in patients with long AL. Prominent nasal thinning likely represents changes from axial elongation. Temporal RNFL thinning in those with long AL tends to be mild, and significant thinning should raise suspicion for glaucoma.

The ISNT Rule: How Often Does It Apply to Disc Photographs and Retinal Nerve Fiber Layer Measurements in the Normal Population?

To determine what percentage of normal eyes follow the ISNT rule, and whether ISNT rule variants may be more generalizable to the normal population. Cross-sectional study. Setting: Institutional setting. Total of 110 normal subjects. Neuroretinal rim assessments from disc photographs and retinal nerve fiber layer (RNFL) thickness measurements from spectral-domain optical coherence tomography. The percentages of subjects that obeyed the ISNT rule and its variants. The ISNT rule is only valid for 37.0% of disc photograph rim assessments and 43.8% of RNFL measurements. Deviation of the nasal sector from the expected ISNT pattern was a major cause for the ISNT rule not being obeyed for both rim and RNFL assessments. Specifically, 10.9% of subjects had wider nasal rims than the inferior rims, 29.4% had wider nasal rims than the superior rims, 14.7% had narrower nasal rims than the temporal rims, and 42.9% had thinner nasal RNFLs compared to the temporal quadrant. Exclusion of the nasal quadrant from the ISNT rule significantly increased the validity of ISNT variant rules, with 70.9% and 76.4% of disc photographs following the IST rule and the IS rule, respectively. Similarly, for RNFL thickness, 70.9% and 71.8% of patients followed the IST and IS rule, respectively. The ISNT rule is only valid for about a third of disc photographs and less than half of RNFL measurements in normal patients. ISNT rule variants, such as the IST and IS rule, may be considered, as they are valid in more than 70% of patients.

Evaluation of Peripapillary Nerve Fiber Layer after Dexamethasone Implantation (Ozurdex) in Branch Retinal Vein Occlusions.

Purpose. To evaluate the peripapillary retinal nerve fiber layer (RNFL) thicknesses of patients treated with intravitreal Ozurdex implant due to branch retinal vein occlusion (BRVO) related macular edema (ME). Methods. Thirty-three eyes of 33 patients treated with Ozurdex implant due to ME associated with BRVO were included in the study. Ophthalmic examinations including determination of best corrected visual acuity (BCVA), measurement of intraocular pressure (IOP), and central macular thickness (CMT) and peripapillary RNFL assessment with optical coherence tomography (OCT) were performed before the injection of Ozurdex implant and during the 6-month follow-up period after the injection. Results. The mean age was 55.2 ± 7.4 (range: 40–68) years. The BCVAs were significantly increased and CMTs were significantly decreased at month 3 and month 6 visits compared to baseline values. The mean IOP was significantly increased from baseline at day 1, week 1, and month 1 visits (p 1 = 0.008, p 2 = 0.018, and p 3 = 0.022, resp.). The average and inferior quadrant peripapillary RNFL thicknesses were significantly reduced at month 6 control visit compared to baseline values (both p < 0.001). Conclusions. Ozurdex implant improved the BCVA and reduced the CMT in the eyes with RVO related ME. However, IOP elevations occurred within the first month after the injection and the average and inferior quadrant RNFL thinning was found six months after the injection. Further controlled studies are warranted.

Optical Coherence Tomography Study of Peripapillary Retinal Nerve Fiber Layer and Choroidal Thickness in Eyes With Tilted Optic Disc

The tilted optic disc is associated with peripapillary choroidal and retinal nerve fiber layer (RNFL) changes as well as visual field defects, often leading to diagnostic difficulties due to similarities with glaucomatous discs. We studied the peripapillary RNFL of the tilted optic disc by comparing values obtained with spectral-domain (SD) and time-domain (TD) optical coherence tomography (OCT) in order to identify characteristic RNFL patterns verified by both OCT devices, and also to determine whether SD-OCT offers any diagnostic advantage over TD-OCT. Prospective case-control study of 16 individuals with tilted optic discs (27 eyes) and an age-matched control group (10 individuals, 20 eyes). Each case was subjected to ophthalmological examination and automated perimetry. Tilt orientation was classified based on observation of optic disc photographs, and angle of disc torsion was calculated with image processing software. RNFL measurements were obtained with TD-OCT and SD-OCT. Peripapillary choroid thickness was measured with SD-OCT. The findings were related with optic disc morphology and automated perimetry results. Stratus OCT results showed significantly lower superior RNFL (P<0.001) on the tilted group, whereas Spectralis indicated significantly lower superotemporal (P<0.001), superonasal (P=0.001), temporal (P=0.01), and global (P=0.01) RNFL on the tilted disc group. A significant correspondence was found between elevated disc rim and location of RNFL defect on the Spectralis (P=0.004). On the tilted group, peripapillary choroidal thickness was significantly thicker adjacent to the elevated rim (P<0.001). No correspondence was found between tilt orientation, peripapillary RNFL, or choroidal thickness and location of perimetric defects. Our results provide a clinical characterization of the main tilted disc morphologies and are valuable for correctly differentiating a tilted disc from a myopic glaucomatous disc. RNFL assessment by Spectralis OCT seems to be more susceptible to altered disc morphologies. The peripapillary RNFL changes found on titled disc cases could not predict the location of visual field defects.

Peripapillary Retinal Nerve Fiber Layer Assessment of Spectral Domain Optical Coherence Tomography and Scanning Laser Polarimetry to Diagnose Preperimetric Glaucoma

PurposeTo compare the abilities of peripapillary retinal nerve fiber layer (RNFL) parameters of spectral domain optical coherence tomograph (SDOCT) and scanning laser polarimeter (GDx enhanced corneal compensation; ECC) in detecting preperimetric glaucoma.MethodsIn a cross-sectional study, 35 preperimetric glaucoma eyes (32 subjects) and 94 control eyes (74 subjects) underwent digital optic disc photography and RNFL imaging with SDOCT and GDx ECC. Ability of RNFL parameters of SDOCT and GDx ECC to discriminate preperimetric glaucoma eyes from control eyes was compared using area under receiver operating characteristic curves (AUC), sensitivities at fixed specificities and likelihood ratios (LR).ResultsAUC of the global average RNFL thickness of SDOCT (0.786) was significantly greater (p<0.001) than that of GDx ECC (0.627). Sensitivities at 95% specificity of the corresponding parameters were 20% and 8.6% respectively. AUCs of the inferior, superior and temporal quadrant RNFL thickness parameters of SDOCT were also significantly (p<0.05) greater than the respective RNFL parameters of GDx ECC. LRs of outside normal limits category of SDOCT parameters ranged between 3.3 and 4.0 while the same of GDx ECC parameters ranged between 1.2 and 2.1. LRs of within normal limits category of SDOCT parameters ranged between 0.4 and 0.7 while the same of GDx ECC parameters ranged between 0.7 and 1.0.ConclusionsAbilities of the RNFL parameters of SDOCT and GDx ECC to diagnose preperimetric glaucoma were only moderate. Diagnostic abilities of the RNFL parameters of SDOCT were significantly better than that of GDx ECC in preperimetric glaucoma.