Position of the fovea centralis with respect to the optic nerve head

Vascular features around the optic disc in familial exudative vitreoretinopathy: findings and their relationship to disease severity

BACKGROUND

Familial exudative vitreoretinopathy (FEVR) is a rare congenital disorder of retinal vascular development. We aimed to study the vascular characteristics around the optic disc in neonates with FEVR and the relationship with disease severity.

METHODS

A retrospective, case-control study including 43 (58 eyes) newborn patients with FEVR at stages 1 to 3 and 30 (53 eyes) age-matched normal full-term newborns was conducted. The peripapillary vessel tortuosity (VT), vessel width (VW) and vessel density (VD) were quantified by computer technology. The t-distributed stochastic neighbor embedding (t-SNE) algorithm was used to visualize the relationship between the severity of FEVR and the characteristics of perioptic disc vascular parameters.

RESULTS

The peripapillary VT, VW and VD were significantly increased in the FEVR group compared with the control group (P < 0.05). Subgroup analysis showed that VW and VD increased significantly with progressing FEVR stage (P < 0.05). And only VT in stage 3 FEVR was significantly increased compared with stage 1 and stage 2 (P < 0.05). After controlling the confounders, ordinal logistic regression analysis indicated that the VW (aOR: 1.75, P = 0.0002) and VD (aOR: 2.41, P = 0.0170) were significantly independent correlated with the FEVR stage, but VT (aOR: 1.07, P = 0.5454) was not correlated with FEVR staging. Visual analysis based on the t-SNE algorithm showed that peri-optic disc vascular parameters had a continuity along the direction of FEVR severity.

CONCLUSIONS

In the neonatal population, there were significant differences in peripapillary vascular parameters between patients with FEVR and normal subjects. Quantitative measurement of vascular parameters around the optic disc can be used as one of the indicators to assess the severity of FEVR.

Baseline Microperimetry and OCT in the RUSH2A Study: Structure-Function Association and Correlation With Disease Severity

PURPOSE

To investigate baseline mesopic microperimetry (MP) and spectral domain optical coherence tomography (OCT) in the Rate of Progression in USH2A-related Retinal Degeneration (RUSH2A) study.

DESIGN

Natural history study METHODS: Setting: 16 clinical sites in Europe and North AmericaStudy Population: Participants with Usher syndrome type 2 (USH2) (N = 80) or autosomal recessive nonsyndromic RP (ARRP) (N = 47) associated with biallelic disease-causing sequence variants in USH2AObservation Procedures: General linear models were used to assess characteristics including disease duration, MP mean sensitivity and OCT intact ellipsoid zone (EZ) area. The associations between mean sensitivity and EZ area with other measures, including best corrected visual acuity (BCVA) and central subfield thickness (CST) within the central 1 mm, were assessed using Spearman correlation coefficients.

MAIN OUTCOME MEASURES

Mean sensitivity on MP; EZ area and CST on OCT.

RESULTS

All participants (N = 127) had OCT, while MP was obtained at selected sites (N = 93). Participants with Usher syndrome type 2 (USH2, N = 80) and nonsyndromic autosomal recessive Retinitis Pigmentosa (ARRP, N = 47) had the following similar measurements: EZ area (median (interquartile range [IQR]): 1.4 (0.4, 3.1) mm2 vs 2.3 (0.7, 5.7) mm2) and CST (median (IQR): 247 (223, 280) µm vs 261 (246, 288), and mean sensitivity (median (IQR): 3.5 (2.1, 8.4) dB vs 5.1 (2.9, 9.0) dB). Longer disease duration was associated with smaller EZ area (P < 0.001) and lower mean sensitivity (P = 0.01). Better BCVA, larger EZ area, and larger CST were correlated with greater mean sensitivity (r > 0.3 and P < 0.01). Better BCVA and larger CST were associated with larger EZ area (r > 0.6 and P < 0.001).

CONCLUSIONS

Longer disease duration correlated with more severe retinal structure and function abnormalities, and there were associations between MP and OCT metrics. Monitoring changes in retinal structure-function relationships during disease progression will provide important insights into disease mechanism in USH2A-related retinal degeneration.

Potential Prognostic Indicators for Patients With Retinal Vein Occlusion

The second most prevalent cause of retinal vascular disease is retinal vein occlusion (RVO). RVO raises intravascular pressure in the capillary and veins, triggering vessel barrier collapse and subsequent leaking of blood or plasma components into the tissue (edema). Macular edema (ME) is a major complication of RVO that results in significant visual impairment. Laser therapy, intravitreal steroid injections, and vascular endothelial growth factor (VEGF) inhibitors are the major therapeutic techniques. Different therapies reduce ME of RVO and improve visual activity. However, some people have no impact on the resolution of ME, while others have a poor visual prognosis despite full ME cure. There are many investigators who studied the relationship between indicators of various instruments with visual activity. However, a summary of those findings is currently lacking. Therefore, we will focus on the predictive factors of different studies associated with positive visual activity outcomes, which would be very useful and important to help address both treatment expectations and methods for patients with RVO.

Inter-eye comparison of retinal vascular growth rate and angiographic findings following unilateral bevacizumab treatment

PURPOSE

To compare retinal vascularization progression rate, final retinal vascularization, and fluorescein angiography (FA) findings in infants who received intravitreal bevacizumab (IVB) treatment in one eye and with spontaneous regression in the other eye.

METHODS

Thirty eyes of 15 infants who underwent IVB in one eye due to asymmetric retinopathy of prematurity, and who had pre-treatment fundus photographs and fluorescein angiography images were included in the study. Horizontal disc diameter (DD), optic disc-to-fovea distance (FD), and the length of temporal retinal vascularization (LTRV) distance were measured by evaluating pre-treatment and FA images.

RESULTS

The mean ages at the time of treatment and FA were 40.38  ±  3.35 and 68.72  ±  10.52 weeks postmenstrual age, respectively. The pre-treatment LTRV/FD ratio was 3.11  ±  0.41 in the treated eyes and 3.26  ±  0.43 in the non-treated eyes (p  =  0.053). The final LTRV/FD ratio was 4.23  ±  0.38 in the treated group and 4.33  ±  0.37 in the non-treated group (p  =  0.286). Staining of the vessels, hyperfluorescent focus, and irregular branching of the vessels were similar between the groups, respectively (p  =  1.000; p  =  0.250; p  =  0.625).

CONCLUSION

The progression rate of retinal vascularization and angiographic findings were similar between the treated eyes and the non-treated eyes. Our study suggests that incomplete retinal vascularization in eyes treated with anti-vascular endothelial growth factor (VEGF) is due to the nature of the disease, and anti-VEGF treatment was not to cause cessation in vascular progression.

The effect of intravitreal bevacizumab dose on retinal vascular progression in retinopathy of prematurity

INTRODUCTION

In this study, we investigate the effect of drug dose on the progression of retinal vascularization in eyes treated with different doses of intravitreal bevacizumab (IVB).

METHODS

The patient charts of 259 eyes of 142 patients who were administered 0.3125 mg or 0.625 mg IVB as primary therapy for type 1 ROP or aggressive ROP (A-ROP) were retrospectively evaluated. Eighty-four eyes of 42 infants met all study inclusion criteria and underwent further morphological evaluation. Eyes treated with 0.3125 mg and 0.625 mg bevacizumab were grouped as the low dose and standard dose groups, respectively. Horizontal disc diameter (DD), optic disc-to-fovea distance (FD), and the length of temporal retinal vascularization (LTRV) were measured on pre-treatment photographs (PP) and final fluorescein angiography (FA) images. LTRV, measured in pixels, was converted to DD and FD units and analyzed. All PPs and FA images were captured with 130° PanoCam Pro camera. The difference between final LTRV and pre-treatment LTRV was defined as the difference of LTRV. The ratio of difference of LTRV to pre-treatment LTRV was defined as the rate of increase of LTRV.

RESULTS

Of the 255 eyes, re-treatment rate before 55 weeks postmenstrual age (PMA) was 23% in the eyes treated with 0.3125 mg IVB and 19% in the eyes treated with 0.625 mg IVB (p = 0.362). Of the 42 infants included for further morphological evaluation, the median age at the time of treatment was 36 (35-38) weeks PMA, and the median age at the time of FA imaging was 66 (62-75) weeks PMA. While the difference of LTRV by unit of DD was higher in the low dose group (p=0.017), this difference was similar between groups by unit of FD (p=0.412). The ratio of the increase of the LTRV was similar between groups by units of DD and FD (p=0.081, p=0.390; respectively). The FD/DD ratio was 4.13 ± 0.49 and 3.26 ± 0.33 at the pre-treatment and final sessions, respectively (p=0.000).

CONCLUSION

The ratio of FD to DD decreased significantly with increasing age. The additional treatment rate and progression of retinal vascularization by unit of FD were similar between the groups. The difference of LTRV by unit of DD was higher in the low dose group. The usage of different formulas and methods may affect the evaluation of the progression of retinal vascularization.

The effect of uncorrected ametropia on ocular torsion induced by changes in fixation

Background and Objective

Ocular torsion, the eye movements to rotating around the line of sight, has not been well investigated regarding the influence of refractive errors. The purpose of this study was to investigate the effect of uncorrected ametropia on ocular torsion induced by fixation distances.

Methods

Seventy-two subjects were classified according to the type of their refractive error, and ocular torsion of the uncorrected eye was compared based on changes induced by different fixation distances. Ocular torsion was measured using a slit-lamp biomicroscope equipped with an ophthalmic camera and a half-silvered mirror.

Results

In all groups, excyclotorsion values increased as the fixation distance decreased, but the myopia and astigmatism groups had larger amounts of ocular torsion than the emmetropia group. In addition, as the amount of uncorrected myopia and astigmatism increased, the amount of ocular torsion increased.

Conclusion

Since the amount of ocular torsion caused by a change to a shorter fixation distance was larger when the refractive error was uncorrected, we suggest that ametropia should be fully corrected in patients frequently exposed to ocular torsion due to changes in fixation distance.

Can Imaging of Temporal Raphe Orientation with fundusphotos or SD-OCT be helpful for the Assessment of Ocular Torsion in Patients with Cranial Nerve Four Paresis?

Strabismic deviations can be horizontal, vertical, cyclorotational, or a combination of all three. Previous literature has established the difference between subjective and traditional objective torsional angles; however, often there is a failure to consider the physiological position of a normal fovea-optic nerve head (ONH) relationship. Using the temporal raphe (TR) orientation has been suggested as a solution for this discrepancy. The current study, approved by IWK Health Center research ethics board was created to assess the viability of using the TR in assessment of ocular torsion as well as investigate the effect of the physiological position of the fundus. Subjective tests were compared to traditional fundus photographs and novel TR scans in patients with long-standing unilateral fourth nerve palsies. Results found no differences between subjective and objective angles when considering the physiological fundus position and that TR angles were not comparable to other torsional testing methods. Therefore, it was concluded that the physiological position should be considered when determining the true amount of abnormal fundus torsion. As well, we found no significant value to using TR imaging by optical coherence tomography compared to the traditional fovea-ONH relationship by fundus photography to assess ocular torsion.

Measurement of ocular counter-roll using iris images during binocular fixation and head tilt

Objective

To compare the ocular counter-roll (OCR) measured using iris images during binocular fixation and head tilt with OCR measured via fundus photography.

Methods

Fifty-three healthy college students participated in this study. The mean OCR was measured by collection of iris images and fundus images under seven head tilt conditions (0 degrees; 10, 20, and 30 degrees right; and 10, 20, and 30 degrees left). Three iris images (crossed pupil center, pupil center, and pupil periphery) were taken using a slit-lamp biomicroscope with an ophthalmic camera and a half-silvered mirror; fundus images were collected via fundus photography. The mean OCR values were compared between images taken with each method.

Results

No iris images or head tilt conditions revealed any significant differences in mean OCR comparison with fundus images. The mean difference in OCR was smallest, and the correlation was greatest, between the crossed pupil center and fundus images.

Conclusion

A half-silvered mirror and iris images can replace fundus photography for the measurement of OCR.

Determining the Location of the Fovea Centralis Via En-Face SLO and Cross-Sectional OCT Imaging in Patients Without Retinal Pathology

Purpose

The purpose was to establish the position of the fovea centralis to the optic nerve via en-face, near-infrared spectral domain optical coherence tomography (NIR-OCT) in healthy patients. This may shed light on physiological variability and be used for studying subtle cases of foveal ectopia in macular pathology and after retinal detachment.

Methods

SD-OCT data of 890 healthy eyes were retrospectively analyzed. Exclusion criteria included axial myopia causing tilting of the optic disc, peripapillary atrophy >1/3 the width of the disc, macular images excluding greater than half of the optic disc, and patients unable to maintain vertical head positioning. Two independent reviewers measured the horizontal and vertical distance from the fovea to the optic disc center and optic disc diameter via cross-sectional and en-face scanning laser ophthalmoloscopy OCT imaging.

Results

890 eyes were included in the study. The right and left eyes differed in the horizontal distance from the fovea to the disc center (4359 vs. 4248 µm, P < 0.001) and vertical distance from the fovea to the disc center (464 µm vs. 647, P < 0.001). This corresponded to a smaller angle between the right and left eyes (6.07° vs. 8.67°, P < 0.001). Older age was associated with a larger horizontal (P = 0.008) and vertical distance (0.025). These differences persisted after correcting for axial length in the 487 patients with axial-length data.

Conclusions

This study compares the position of the fovea centralis among individuals without macular pathology on a micron level basis. The significant variability between right and left eyes indicates that contralateral eye evaluation cannot be reliably used. Rather, true foveal ectopia requires assessments of preoperative and postoperative NIR-OCT scans. This finding is relevant to retinal detachment cases and evaluation of subtle foveal ectopia.

Translational Relevance

This finding is relevant to retinal detachment cases and evaluation of subtle foveal ectopia.

Factors influencing the result of superior oblique weakening procedures in patients with superior oblique overaction in horizontal strabismus

Background

Few studies have evaluated the surgical outcome of superior oblique weakening procedures in patients with superior oblique overaction associated with exotropia or esotropia. This study aimed to evaluate the outcome of superior oblique muscle weakening and the influencing factors in patients with superior oblique overaction.

Methods

The medical charts of 37 patients (55 eyes) with superior oblique overaction associated with esotropia or exotropia who were treated with a superior oblique weakening procedure at the Seoul National University Hospital from January 2010 to June 2017 were retrospectively reviewed. Superior oblique overaction was graded using, a 6-point scale ranging from + 0.5 to + 3, and pre- and postoperative grades were recorded for all patients.

Results

The mean age of the patients was 91.81 ± 59.37 months. Superior oblique muscle suture spacer and superior oblique posterior tenectomy were performed for 17 (23 eyes) and 20 (32 eyes) patients, respectively. Surgical success was achieved in 15 (65.2%) eyes in the suture spacer group and 23 (71.9%) eyes in the posterior tenectomy group. Surgical success was achieved for 69.1% (38/55 eyes) of patients. Dissociated vertical deviation exhibited a significant negative association with the surgical success rate (p < 0.001).

Conclusions

There was no significant difference in surgical success rate between the superior oblique posterior tenectomy and superior oblique suture spacer groups in superior oblique overaction associated with horizontal strabismus. Associated dissociated vertical deviation can affect the surgical success of the superior oblique weakening procedure.

Microvascular Phenotyping in the Maastricht Study: Design and Main Findings, 2010-2018

Microvascular dysfunction (MVD) is a common pathophysiological change that occurs in various diseases, such as type 2 diabetes mellitus (T2DM), heart failure, dementia, and depression. Recent technical advances have enabled noninvasive measurement and quantification of microvascular changes in humans. In this paper, we describe the protocols of the microvascular measurements applied in the Maastricht Study, an ongoing prospective, population-based cohort study of persons aged 40–75 years being carried out in the southern part of the Netherlands (baseline data assessment, November 2010–January 2020). The study includes a variety of noninvasive measurements in skin, retina, brain, and sublingual tissue, as well as plasma and urine biomarker assessments. Following this, we summarize our main findings involving these microvascular measurements through the end of 2018. Finally, we provide a brief perspective on future microvascular investigations within the framework of the Maastricht Study.

Eyes With Acute, Treatment-Naïve CRVO and Foveal Intraretinal Hemorrhage: Characteristics and Outcomes

BACKGROUND AND OBJECTIVE

To compare outcomes in eyes with central retinal vein occlusion (CRVO) presenting with (group 1) or without (group 2) fovea-involving intraretinal hemorrhage (IRH).

PATIENTS AND METHODS

Retrospective review of patients diagnosed with acute, treatment-naïve CRVO between January 2009 and July 2016.

RESULTS

One hundred fifteen (39.8%) of 289 CRVO eyes had fovea-involving IRH. At baseline, eyes in group 1 had significantly worse visual acuity (VA) (1.2 ± 0.10 logMAR vs. 0.9 ± 0.06 logMAR; P = .001) and greater central subfield thickness (CST) (610.4 μm ± 35.9 μm vs. 435.0 μm + 21.6 μm; P < .001) than eyes in group 2. Final visual outcomes were comparable between groups (1.24 ± 0.09 logMAR vs. 1.02 ± 0.08 logMAR; P = .08). Group 1 received a significantly greater number of intravitreal anti-vascular endothelial growth factor injections during the first year (7.80 ± 0.40 vs. 5.20 ± 0.40; P = .001).

CONCLUSIONS

Although treatment-naïve eyes with acute CRVO and fovea-involving IRH had worse VA and greater CST at presentation, the final VA was comparable to eyes without such a hemorrhage. Eyes with foveal IRH had a greater treatment burden in the first 12 months. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:752-759.].

Objective cyclodeviation measurement in normal subjects by means of Cyclocheck® application

PURPOSE

To evaluate the range of cyclodeviation in normal individuals by means of Cyclocheck^® application recently designed by the authors and freely available at www.cyclocheck.com.

METHODS

Healthy subjects with normal muscle balance, best-corrected visual acuity of ⩾0.8, and stereopsis on Randot charts of ⩽100 s of arc were included in the study. Two separate digital fundus photographs were taken of each eye of every patient. The disk-foveal angle was calculated using the Cyclocheck^® application. The average result of the disk-foveal angle measurements were considered for data analysis.

RESULTS

A total of 131 patients met inclusion criteria for the study population. The mean value of the disk-foveal angle in the whole study group (both right and left eye) was 6.39° ± 2.72° with 5.26° ± 2.56° (range from -0.4° to 12.55°) in the right eye and 7.52° ± 2.39° (range from 1.25° to 12.76°) in the left eye. The mean value of the disk-foveal angle of the left eye was greater by 2.26° than that of the right eye.

CONCLUSION

Cyclocheck^® software allows easy assessment of cyclodeviation. Normal individuals present with a positive value of the disk-foveal angle with a certain spread of the results. The analysis of obtained measurements revealed a significant asymmetry between both eyes with the left eye being more excyclodeviated in an otherwise orthotropic population, which remains a subject for further investigations.

Optical coherence tomography angiography for the measurement of optic disc: Macular relationship

INTRODUCTION

Fundus photography is the gold standard for assessing ocular torsion over the last 30 years. However, it is not a precise and reproducible tool during clinical practice. Optical coherence tomography angiography is characterized by precise identification of the macula and the optic disc, and it could be an effective method to easily calculate the angle of ocular torsion, compared to fundus photography. The aim of this study was to show whether any difference in the measurement and the accuracy of the angle of torsion between the head of the optic nerve and the fovea was present.

METHODS

This is a prospective single-, referral-center study conducted at the San Giuseppe Hospital in Milan on 80 eyes of 40 adult patients, included in a random-sample way. Exclusion criteria were non-cooperation, higher refractive errors of ±3 diopters, retinal and optic disc pathologies, and ocular movement disorders.

RESULTS

Patients' mean age was 54.3 ± 16.3 (range: 22-83) years. The angle measured by the fundus camera was 7.78° ± 3.04°, while the angle measured by the angiography was 7.09° ± 3.08° (p = .035). The mean interocular difference was 1.54° ± 3.42° for fundus photography and 0.5° ± 4.71° for angiography (p = .013).

CONCLUSION

Optical coherence tomography angiography is a very useful, fast, precise, reproducible, and reliable technique in cooperative subjects, not inferior to the fundus camera and less prone to human error.

Disc-foveal angle and ocular counterrolling as a key in its interpretation

PURPOSE

Describe a time-sparing technique to measure disc-foveal angle (DFA), determine normal values and its role when analyzing paired fundus photographs.

METHODS

DFA was analysed using the software program Keynote v.6.2.2 on 440 fundus photographs (3D OCT 2000, Topcon Corporation, Tokio, Japan) of 20 individuals. The 11 different head positions were determined with the cervical range of motion device (CROM, Performance Attainment Associates). A reproducibility and correlation study between two fundus cameras (OCT 3D-2000 and TRC-50EX, Topcon Corporation, Tokio, Japan) was performed.

RESULTS

Mean DFA of the right and left eye was 5.5±3.4° and 8.6±2.9°, with a difference of 3.1° (P=0.001 Wilcoxon signed-rank test) in the upright head position. Mean absolute difference in DFA between eyes was 3.5±2.6°; an increase was seen with increasing head tilt (P=0.000 Wilcoxon signed-rank test). Mean sum of DFA in both eyes was 14.1±5.4°. On head-tilt of 20° and 40° to the right, mean ocular counterrolling (OCR) was 7.1° and 12.2° in the right eye and 7.7° and 12.1° in the left eye. On head-tilt of 20° and 40° to the left, OCR was 4.4° and 8° in the right eye and 4.2° and 8.7° in the left eye (P=0.000 Wilcoxon signed-rank test). The two cameras showed strong correlation and high reproducibility.

CONCLUSIONS

Our DFA measurement technique is time-sparing and reproducible. Left eye shows higher DFA than right eye. OCR occurs only in the roll plane. This information is of value when analyzing paired fundus photographs.

The Horizontal Raphe of the Human Retina and its Watershed Zones

The horizontal raphe (HR) as a demarcation line dividing the retina and choroid into separate vascular hemispheres is well established, but its development has never been discussed in the context of new findings of the last decades. Although factors for axon guidance are established (e.g., slit-robo pathway, ephrin-protein-receptor pathway) they do not explain HR formation. Early morphological organization, too, fails to establish a HR. The development of the HR is most likely induced by the long posterior ciliary arteries which form a horizontal line prior to retinal organization. The maintenance might then be supported by several biochemical factors. The circulation separate superior and inferior vascular hemispheres communicates across the HR only through their anastomosing capillary beds resulting in watershed zones on either side of the HR. Visual field changes along the HR could clearly be demonstrated in vascular occlusive diseases affecting the optic nerve head, the retina or the choroid. The watershed zone of the HR is ideally protective for central visual acuity in vascular occlusive diseases but can lead to distinct pathological features.

Distribution of Diabetic Neovascularization on Ultra-Widefield Fluorescein Angiography and on Simulated Widefield OCT Angiography

PURPOSE

Areas of neovascularization (NV) in proliferative diabetic retinopathy (PDR) on ultra-widefield (UWF) fluorescein angiography (FA) were identified and compared with a simulated widefield (WF) swept-source OCT angiography (SS-OCTA) field of view to determine whether the WF SS-OCTA field of view was sufficient for detection of NV in PDR.

DESIGN

Retrospective, consecutive case series.

METHODS

All patients with PDR and UWF FA imaging at the Bascom Palmer Eye Institute over a period of 5.5 years were identified. UWF FA images were reviewed and sites of NV were identified either as NV of the disc or NV elsewhere. Sites of NV elsewhere were classified by disc-centered retinal quadrants. A simulated WF SS-OCTA montage field of view was overlaid on the UWF FA images to determine whether sites of NV would have been identified by this simulated WF SS-OCTA field of view.

RESULTS

A total of 651 eyes with PDR from 433 patients had at least 1 UWF FA with NV. Of the 651 eyes, 50% were treatment-naïve, 9.8% had NV of the disc only, 41.8% had NV elsewhere only, and 48.4% had both NV of the disc and NV elsewhere. NV elsewhere was most prevalent in the superotemporal quadrant and the least prevalent in the nasal quadrants. When the simulated WF SS-OCTA field of view was overlaid on the UWF FA, 98.3% of all eyes, 99.4% of treatment-naive eyes, and 97.2% of previously treated eyes had NV within the WF SS-OCTA field of view. In those eyes with a repeat UWF FA within 6 to 18 months of the first FA, the distribution of NV did not change in either the treatment-naive or previously treated eyes.

CONCLUSIONS

NV elsewhere in PDR was most prevalent superotemporally, and 99.4% of treatment-naïve eyes had NV within the simulated WF SS-OCTA field of view. Combined with previous research using WF SS-OCTA to identify NV in PDR, these findings suggest that WF SS-OCTA may be the only imaging modality needed for the diagnosis and longitudinal management of PDR.

Impact and Implication of Fovea-Involving Intraretinal Hemorrhage after Acute Branch Retinal Vein Occlusion

PURPOSE

To compare clinical outcomes in patients with branch retinal vein occlusion (BRVO) with (group A) or without (group B) fovea-involving intraretinal hemorrhage (IRH).

DESIGN

Retrospective cohort study.

PARTICIPANTS

All patients diagnosed with acute, treatment-naive BRVO seen by the Duke Eye Center Retina Service from January 1, 2009, through June 30, 2017 who had treatment-naive BRVO with disease onset <3 months before presentation, macular involvement, spectral-domain OCT and color fundus photographs at presentation, and >12 months offollow-up.

METHODS

Retrospective study using a database of patients diagnosed with BRVO over an 8-year period. The presence of fovea-involving IRH was determined from baseline fundus photographs by human graders and confirmed with multimodal imaging. Presenting features, treatment patterns, and clinical outcomes were compared.

MAIN OUTCOME MEASURES

Visual acuity (VA), cystoid macular edema (CME), central subfield thickness (CST), and number of anti-vascular endothelial growth factor (VEGF) injections.

RESULTS

Of 172 patients with BRVO, 33 (19.2%) presented with fovea-involving IRH. At presentation, group A had worse VA (0.54±0.06 logMAR [Snellen equivalent, 20/69] vs. 0.34±0.03 logMAR [Snellen equivalent, 20/44]; P = 0.001), greater CST (523.8±32 μm vs. 345.9±11.8 μm; P < 0.001), were more likely to have CME (93.9% vs. 48.2%; P < 0.001), and received more anti-VEGF injections in the first year (4.50±3.43 vs. 1.89±3.26; P < 0.001) than group B. Final VA was worse in group A (0.57±0.12 logMAR [Snellen equivalent, 20/74] vs. 0.35±0.05 logMAR [Snellen equivalent, 20/45]; P = 0.05). More patients in group A had loss of >2 lines of VA (36.4% vs. 18.7%; P = 0.04) or >3 lines (27.3% vs. 10.8%; P = 0.05) at final follow-up. Group A was more likely to have CME (63.6% vs. 27.3%; P < 0.001) at final follow-up with greater treatment burden, yet experienced a greater decrease in CST (-197.8±45.3 μm vs. -51.7±14.7 μm; P = 0.005).

CONCLUSIONS

Acute BRVO presenting with fovea-involving IRH is associated with worse presenting features, greater treatment burden, and worse clinical outcomes despite current therapeutic interventions.

Wide-field choroidal thickness in myopes and emmetropes

There is a paucity of knowledge regarding the normal in-vivo thickness of the choroid beyond the macula (~17°). In this study, the choroidal thickness of 27 healthy young adults was examined across the macular (the central 5 mm including the fovea, parafovea, and perifovea) and extra-macular (a 5-14 mm annulus including the near-periphery and periphery) regions using wide-field optical coherence tomography, and compared between emmetropes (n = 14) and myopes (n = 13). The choroid progressively thinned beyond the parafovea (350 ± 86 µm) towards the periphery (264 ± 44 µm), and was thickest superiorly (355 ± 76 µm) and thinnest nasally (290 ± 79 µm). Choroidal thickness also varied with refractive error; myopes exhibited a thinner choroid than emmetropes in the macular region (311 ± 88 vs. 383 ± 66 µm), however, this difference diminished towards the periphery (251 ± 48 vs. 277 ± 37 µm). Meridional variations in choroidal thickness were not different between myopes and emmetropes. In conclusion, the choroid was thickest within the perifovea; thinned substantially towards the periphery, and exhibited the minimum and maximum peripheral thinning superiorly and nasally across a 55° region respectively. Choroidal thinning associated with myopia was more pronounced in the macular than extra-macular regions.

Reliability of objective ocular torsion assessment using fundus photography in infantile esotropia

PURPOSE

To evaluate the interobserver reproducibility of objective ocular torsion measurements in infantile esotropia using fundus photography analysis.

MATERIALS AND METHODS

This retrospective observational study was conducted in our ophthalmology department at the University Hospital in Tours from 2009 to 2015.

OBJECTIVE

Ocular torsion was assessed using fundus photography and analysed on Adobe Photoshop software within a population of children with infantile esotropia. Two observers, an orthoptist and an ophthalmologist, carried out the evaluation separately. The interobserver agreement was calculated for quantitative measurement by the interclass correlation coefficient (ICC) and by Cohen's Kappa coefficient for qualitative assessment.

RESULTS

A total of 200 eyes (100 subjects, mean age: 6.88 years) were assessed. Statistical analyses for quantitative measurements resulted in an ICC of 0.98 (95% CI, 0.97-0.99) for right eyes, 0.96 (95% CI, 0.95-0.97) for left eyes, 0.98 (CI 95%, 0.97-0.98) for pre- operative eyes and 0.96 (95% CI, 0.95-0.97) for postoperative eyes. The ICC calculated on all four hundred fundus photographs was 0.97 (95% CI, 0.97-0.98). The interobserver agreement for qualitative measurements resulted in a Kappa coefficient of 0.91 for right eyes, 0.85 for left eyes, 0.90 for preoperative eyes and 0.86 for postoperative eyes. The analysis of all four hundred eyes returned a Kappa coefficient of 0.88.

CONCLUSIONS

Objective ocular torsion assessment using our procedure, whether by an orthoptist or ophthalmologist, is a reliable and reproducible method for the management of infantile esotropia.

The subjectivity of objective evaluation of torsion on fundus photographs by practicing strabismologists

Purpose:

To assess the variability of assessing the ocular torsion on fundus photographs among strabismus surgeons.

Methods:

This was a prospective, noninterventional, clinical trial involving 16 trained and experienced squint surgeons participated in the study. Two videos were prepared of a total of 10 fundus pictures with or without lines for disc foveal angle. The first video had a 4 s viewing time for each fundus image. The second video had the disc foveal lines drawn and a similar 4 s viewing time for each image. The participants were asked to grade the torsion. The primary outcome measure was to assess the agreement between the raters for ocular torsion measurement. Difference in the response of observers from the standard response was the secondary outcome measure.

Results:

A 4 s viewing time was given to mimic the exposure time in the clinic while assessing torsion in a patient. Large variability was found among the responses. The kappa test was done for comparing the agreement between various observers which ranged from slight to fair (<0.40). There was no difference in torsion grading in 30.6% and 26.3% responses in the first and second video from the standard response, respectively. When a limit of ±1 grade was taken as acceptable for the responses, 66.2% for the first and 68.7% for the second video respectively were similar to standard response.

Conclusion:

There is wide variability in assessing ocular torsion by fundus photography. The level of accuracy does increase with marking the line on photographs but still remains unreliable.

Surgical outcome of superior rectus transposition in esotropic Duane syndrome and abducens nerve palsy

PURPOSE

To evaluate surgical outcome of superior rectus transposition (SRT) in esotropic Duane syndrome (DS) and abducens nerve palsy.

METHODS

Retrospective medical record analysis of all patients with esotropic DS and abducens nerve palsy treated with SRT at our center with minimum follow-up of 6 months. Primary outcome measures were esotropia in primary position and abduction limitation. Secondary outcome measures included head turn, stereopsis, and cyclovertical deviations.

RESULTS

A total of 20 eyes of 19 patients were included: 9 with DS and 10 with traumatic abducens nerve palsy. One patient had bilateral esotropic DS. Mean age of DS patients was 12.5 ± 10.1 years; of abducens nerve palsy patients, 25.4 ± 11.3 years. Medial rectus recession (MRc) of 3.5 mm was additionally performed in 5 DS eyes. An adjustable MRc 5.6 ± 2.2 mm with or without augmentation suture was performed in all abducens nerve palsy patients. In DS patients, esotropia improved from 27.5^Δ ± 5.4^Δ to 3.6^Δ ± 6.4^Δ (P < 0.001), abduction limitation reduced from -3.8 to -1.8 (P < 0.001), and head posture improved from 20° to 4° (P < 0.001) at 6 months. In abducens nerve palsy patients, esotropia improved from 51.5^Δ ± 18.8^Δ to 6.1^Δ ± 10.7^Δ (P < 0.001), abduction limitation reduced from -3.8 to -2, and head posture improved from 25° to 8° (P < 0.001). Stereopsis improved in 4 patients (P = 0.12). No patient had vertical deviation or torsional diplopia.

CONCLUSIONS

In our patient cohort with esotropic DS or abducens nerve palsy, SRT reduced esotropia and improved abduction. Because of a long-term exotropic drift, initial undercorrection in the immediate postoperative period may prevent eventual overcorrection.

Cyclocheck: a new web-based software for the assessment of objective cyclodeviation

PURPOSE

To present a novel, free, web-based software tool (www.cyclocheck.com) for the assessment of objective cyclodeviation, based on measuring the disk-foveal angle (DFA) and to evaluate reproducibility of the results.

METHODS

Digital fundus photographs of both eyes of all study subjects were obtained using DRS CenterVue nonmydriatic fundus camera. Four separate measurements were made for each eye, and the DFA was calculated using Cyclocheck software independently by two observers to determine reproducibility and repeatability of the technique. The results were statistically analyzed using the interclass correlation coefficient (ICC) and the Bland-Altman method.

RESULTS

A total of 32 subjects (mean age, 34.4; range, 12-83) were enrolled: 18 were orthophoric; 14, strabismic. The ICC for the intraobserver repeatability for one observer was 0.979 (95% CI, 0.970-0.985; P < 0.0005) and for the other was 0.988 (95% CI, 0.983-0.991; P < 0.0005). The ICC for the interobserver agreement was 0.994 (95% CI, 0.992-0.996; P < 0.0005), indicating high reproducibility of the measurements.

CONCLUSIONS

Cyclocheck can assess ocular torsion quickly and easily. It provides reliable and reproducible measurements of the DFA and thus objective cyclodeviation in both orthophoric and strabismic subjects.

The Location of the Deepest Point of the Eyeball Determines the Optic Disc Configuration

Tilted and rotated appearances are hallmarks of the myopic optic disc. As the eyeball grows axially, the posterior pole elongates not only globally but in a localized manner as well. In this process, the optic disc is pulled towards the deepest point of the elongated eyeball, which might result in a change in optic disc configuration. Thus, we hypothesized that analyzing the variation of posterior pole contour can play a major role in understanding optic disc configuration in myopic subjects. By analyzing consecutive images of swept source OCT coronal sections at the posterior pole, the deepest interface between Bruch's membrane and the choroid could be identified as the deepest point of the eyeball (DPE). The location and the properties of the DPE differed significantly between the 125 eyes of non-glaucomatous myopic group and the 40 eyes of non-glaucomatous emmetropic group classified based on 24 mm axial length. The results suggested that the larger disc to DPE angle and the larger disc to DPE depth strongly predicts the optic disc torsion degree and the optic disc tilt. Our findings suggest that identifying the posterior pole profile plays a major role in understanding the optic disc alterations found in myopic subjects.

Reliability of Using Retinal Vascular Fractal Dimension as a Biomarker in the Diabetic Retinopathy Detection

The retinal fractal dimension (FD) is a measure of vasculature branching pattern complexity. FD has been considered as a potential biomarker for the detection of several diseases like diabetes and hypertension. However, conflicting findings were found in the reported literature regarding the association between this biomarker and diseases. In this paper, we examine the stability of the FD measurement with respect to (1) different vessel annotations obtained from human observers, (2) automatic segmentation methods, (3) various regions of interest, (4) accuracy of vessel segmentation methods, and (5) different imaging modalities. Our results demonstrate that the relative errors for the measurement of FD are significant and FD varies considerably according to the image quality, modality, and the technique used for measuring it. Automated and semiautomated methods for the measurement of FD are not stable enough, which makes FD a deceptive biomarker in quantitative clinical applications.

Changes in the axis of astigmatism and in fundus torsion following inferior oblique muscle weakening

PURPOSE

To study the changes in fundus torsion and in the axis of astigmatism following inferior oblique (IO) myectomy in patients with inferior oblique overaction (IOOA).

METHODS

The degree of fundus torsion and corneal astigmatism were prospectively evaluated before and 3 months after IO myectomy in patients with IOOA grade +2 or more in one or both eyes and an astigmatic error of ≥1 D. Fundus torsion was evaluated by measuring the disk foveal angle (DFA) using fundus photography. The axis of astigmatism was identified from the anterior sagittal map using Pentacam corneal imaging.

RESULTS

A total of 54 eyes of 27 patients were included. Patients were divided into two groups: those with esotropia and those with exotropia. All patients had a preoperative DFA >8°, which decreased postoperatively in both groups (P < 0.01). Postoperatively, there was incyclorotation of the axis of astigmatism by >5° in 80% of the esotropic group and 75% of the exotropic groups (P < 0.01).

CONCLUSIONS

Incyclorotation of the axis of astigmatism occurs after IO myectomy. Measurement of the change in the axis of astigmatism can be used to assess the torsional changes after IO myectomy in patients with IOOA.

Optical coherence tomography of the preterm eye: from retinopathy of prematurity to brain development

Preterm infants with retinopathy of prematurity are at increased risk of poor neurodevelopmental outcomes. Because the neurosensory retina is an extension of the central nervous system, anatomic abnormalities in the anterior visual pathway often relate to system and central nervous system health. We describe optical coherence tomography as a powerful imaging modality that has recently been adapted to the infant population and provides noninvasive, high-resolution, cross-sectional imaging of the infant eye at the bedside. Optical coherence tomography has increased understanding of normal eye development and has identified several potential biomarkers of brain abnormalities and poorer neurodevelopment.

Association between Corneal Deformation Amplitude and Posterior Pole Profiles in Primary Open-Angle Glaucoma

PURPOSE

To investigate the relationships between corneal deformation amplitude and posterior pole profiles, including β-zone parapapillary atrophy (βPPA), optic disc tilt ratio, torsion degree, and disc-foveal angle, in patients with glaucoma.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 107 patients with glaucoma.

METHODS

Each patient underwent measurement of deformation amplitude with Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany), color optic disc photography, red-free retinal nerve fiber layer photography, axial length measurement, and 24-2 standard automated perimetry. From fundus photographs, the βPPA area, optic disc tilt ratio, torsion degree, and disc-foveal angle were obtained. Pearson's correlation was used to determine the relationships between deformation amplitude and posterior pole profiles. To determine the factors associated with the posterior pole profiles, univariate and multivariate regression analyses were performed.

MAIN OUTCOME MEASURES

Deformation amplitude, βPPA area, optic disc tilt ratio, torsion degree, and disc-foveal angle.

RESULTS

The study included 50 men (46.7%) and 57 women (53.3%). The mean age was 55.38±14.14 years. The mean tilt ratio, torsion degree, and disc-foveal angle were 1.16±0.14, 10.26±7.63°, and 7.60±3.64°, respectively. The mean βPPA area was 18 211.00±28 725.53 pixels. The βPPA (r = 0.391, P < 0.001) and tilt ratio (r = 0.408, P < 0.001) had significant relationships with deformation amplitude after adjusting for intraocular pressure (IOP). Torsion degree and disc-foveal angle showed no significant relationship with deformation amplitude. The βPPA area was associated with deformation amplitude and axial length in both univariate (P = 0.008 and 0.006, respectively) and multivariate (P = 0.035 and <0.001, respectively) regression analyses. The tilt ratio was associated with deformation amplitude in univariate regression analysis (P = 0.002), but not in multivariate regression analysis. Axial length was significantly associated with the tilt ratio in both univariate (P < 0.001) and multivariate (P < 0.001) regression analyses.

CONCLUSIONS

Deformation amplitude was associated with PPA area and tilt ratio in patients with glaucoma, although in our data set βPPA area and tilt ratio were not associated with visual field mean deviation.

Angiographic Cystoid Macular Edema and Outcomes in the Comparison of Age-Related Macular Degeneration Treatments Trials

PURPOSE

To describe morphologic and visual outcomes in eyes with angiographic cystoid macular edema (CME) treated with ranibizumab or bevacizumab for neovascular age-related macular degeneration (nAMD).

DESIGN

Prospective cohort study within a randomized clinical trial.

PARTICIPANTS

A total of 1185 CATT study subjects.

METHODS

Baseline fluorescein angiography (FA) images of all CATT study eyes were evaluated for CME. Grading of other characteristics on optical coherence tomography (OCT) and photographic images at baseline and during 2-year follow-up was completed by readers at the CATT Reading Centers. Three groups were created on the basis of baseline CME and intraretinal fluid (IRF) status: (1) CME, (2) IRF without CME, (3) neither CME nor IRF.

MAIN OUTCOME MEASURES

Visual acuity (VA) and total central retinal thickness (CRT) on OCT at baseline, year 1, and year 2.

RESULTS

Among 1131 participants with images of sufficient quality for determining CME and IRF at baseline, 92 (8.1%) had CME, 766 (67.7%) had IRF without CME, and 273 (24.1%) had neither. At baseline, eyes with CME had worse mean VA (letters) than eyes with IRF without CME and eyes with neither CME nor IRF (52 vs. 60 vs. 66 letters, P < 0.001); higher mean total CRT (μm) on OCT (514 vs. 472 vs. 404, P < 0.001); and greater hemorrhage, retinal angiomatous proliferation (RAP) lesions, and classic choroidal neovascularization (CNV). All groups showed improvement in VA at follow-up; however, the CME group started and ended with the worst VA among the 3 groups. Central retinal thickness, although higher at baseline for the CME group, was similar at 1 and 2 years follow-up for all groups. More eyes with CME (65.3%) developed scarring during 2 years of follow-up compared with eyes with IRF without CME (43.8%) and eyes with neither CME nor IRF (32.5%; P < 0.001).

CONCLUSIONS

In CATT, eyes with CME had worse baseline and follow-up VA, although all groups showed similar rates of improvement in VA during 2 years of follow-up. Cystoid macular edema seems to be a marker for poorer visual outcomes in nAMD because of underlying baseline retinal dysfunction and subsequent scarring.

Effect of Adjusting Retinal Nerve Fiber Layer Profile to Fovea-Disc Angle Axis on the Thickness and Glaucoma Diagnostic Performance

PURPOSE

To compare optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness, specificity, and glaucoma discriminating ability prior and following adjustment to the fovea-disc angle axis.

DESIGN

Cross-sectional observational study.

METHODS

Fovea-disc angle was measured in 282 healthy subjects (normative database), 46 nonglaucomatous myopic subjects, and 86 glaucomatous subjects. The fovea-disc angle was determined using the Cirrus PanoMap feature after registering the macular ocular fundus image to the peripapillary ocular fundus image. RNFL prediction limits, specificity, and glaucoma discrimination ability were determined before and after adjustment to fovea-disc angle axis.

RESULTS

The mean fovea-disc angles were 7.4 ± 4.1 degrees (normative database), 7.1 ± 4.3 degrees (myopic subjects), and 7.6 ± 4.2 degrees (glaucomatous subjects) (all P > .05). Standard and fovea-disc angle-adjusted RNFL thicknesses showed small significant differences in quadrants and larger differences in clock-hour sectors (all P < .05), without consistent patterns in the direction of the change. The specificity remained unchanged for all parameters in normative database subjects after adjustment to fovea-disc angle. The number of sectors with improved specificity and those with worsened specificity did not differ significantly in the first (8 vs 6), second (5 vs 8), and random (6 vs 7) normative database half (all P > .05). In myopic subjects, the specificity improved and worsened in 4 sectors in each case. The glaucoma discriminating ability significantly increased in 6 sectors and decreased in 5 others.

CONCLUSION

Correcting the RNFL profiles using the fovea-disc angle axis had no consistent effect on the thickness, specificity, and glaucoma diagnostic performance of RNFL parameters. This phenomenon may be specific to different OCT platforms.

Assessment of retinal nerve fiber layer thickness in healthy, full-term neonates

PURPOSE

To measure average retinal nerve fiber layer (RNFL) thicknesses in healthy, full-term neonates.

DESIGN

Descriptive research to develop normative data.

METHODS

Healthy infants born between 37 and 42 weeks postmenstrual age were imaged with hand-held spectral-domain optical coherence tomography. A custom script segmented the RNFL; the fovea and optic nerve center were manually selected. A second script measured the average RNFL thickness along the papillomacular bundle, defined as the arc from -15 degrees to +15 degrees on the axis from the optic nerve to fovea, with radii of 1.1, 1.3, 1.5, and 1.7 mm from the center of the optic disc. Shapiro-Wilk W tests assessed these measurements for normality to determine the age-appropriate radial distance for subsequent analyses. Average RNFL thicknesses for four temporal 45-degree sectors (superior temporal, temporal superior, temporal inferior, and inferior temporal) and the temporal quadrant were calculated and compared to demographic parameters for all infants.

RESULTS

Fifty full-term infants were adequately imaged for RNFL analysis. RNFL thicknesses at 1.5 mm radial distance from the optic nerve were the most normally distributed. While there was a trend toward greater mean superior temporal RNFL thickness for both black and Hispanic vs white infants (128 ± 27 μm, 124 ± 30 μm, and 100 ± 19 μm, respectively, P = .04 for both comparisons), there were no other significant differences noted in RNFL thicknesses by race, sex, gestational age, or birth weight.

CONCLUSIONS

We present RNFL thickness measurements for healthy, full-term infants that may serve as normative data for future analyses.

Difference in the posterior pole profiles associated with the initial location of visual field defect in early-stage normal tension glaucoma

PURPOSE

To identify the differences in posterior pole profiles between early normal tension glaucoma (NTG) patients with an initial central visual field (VF) loss and those with a peripheral VF loss.

METHODS

Normal tension glaucoma patients with parafoveal scotoma (PFS; within a central 10° of fixation; superior, n=47; inferior, n=24) and peripheral nasal step (PNS; VF defect in the nasal meridian outside 10° of fixation; superior, n=27; inferior, n=32) in either hemifield were enrolled, if their mean deviation was greater than -10 decibels (dB). Disc tilt (tilt ratio), disc torsion, area of peripapillary atrophy and disc-foveal angle (angle between a horizontal line through the disc centre and the line connecting the fovea and the disc centre) were analysed from red-free fundus photographs.

RESULTS

The mean disc-foveal angles (shortest diameter) in PNS and PFS groups were 6.2±4.5 and 7.7±4.0°, respectively. In multivariate analysis, eyes with PFS were associated with a greater disc-foveal angle, compared with PNS (p=0.042). In subgroup analysis, superior PFS group showed greater disc-foveal angle compared with inferior PFS group (p=0.018). In the PNS group, the direction of disc torsion was associated with superior and inferior hemifield defects (p=0.004).

CONCLUSIONS

The posterior pole profiles were different in NTG patients according to their location of damage. Disc-foveal angle was the major determinant of the VF location in patients with VF loss at the central region and disc torsion in patients with loss at the peripheral region.

Design and validation of a method to determine the position of the fovea by using the nerve-head to fovea distance of the fellow eye

Purpose

To measure the nerve-head to fovea distance (NFD) on fundus photographs in fellow eyes, and to compare the NFD between fellow eyes.

Methods

Diabetic patients without retinopathy, (n = 183) who were screened by fundus photography at the University Medical Center Groningen, the Netherlands from January 1^st 2005 until January 1^st 2006 were included. The NFD was measured in left and right eyes both from the center and from the rim of the nerve-head. To determine inter- and intra-observer agreement, repeated measurements by one observer (n = 3) were performed on all photographs and by two observers on 60 photographs (30 paired eyes). The effect of age, gender, and refractive error on NFD was analysed.

Results

The correlation of NFDs between the left and the right eye was 0.958 when measured from the center of the nerve head (mean difference 0.0078 mm. ±SD 0.079 (95% limits of agreement −0.147–0.163)) and 0.963 when measured from the rim (mean difference 0.0056±SD 0.073 (95% limits of agreement −0.137–0.149)). Using the NFD between fellow eyes interchangeably, resulted in a standard error of 0.153 mm. Intra- and inter-observer variability was small. We found a significant effect of age (center of the nerve-head (P = 0.006) and rim of the nerve head (P = 0.003)) and refractive error (center of nerve-head (P<0.001) and rim of nerve head (P<0.001)) on NFD.

Conclusions

The NFD in one eye provides a confident, reproducible, and valid method to address the position of the fovea in the fellow eye. We recommend using the NFD measured from the center of the nerve-head since the standard error by this method was smallest. Age and refractive error have an effect on NFD.

Visual pathway-related horizontal reference plane for three-dimensional craniofacial analysis

OBJECTIVES

To construct three-dimensional (3D) horizontal reference planes based on visual pathway and to determine their stability and reliability by analyzing the structural patterns of normal and dysmorphology for 3D craniofacial analysis.

SETTING AND SAMPLE POPULATION

Thirty-six subjects with maxillofacial dysmorphology and malocclusion, and eight normal controls. MATERIALS AND METHODS POPULATION: On the 3D computed tomographic images of the subjects, the visual pathway-based planes, including the orbital axis plane (OAP), visual axis plane (VAP), and the optical axis plane (OpAP), were constructed and evaluated.

RESULTS

The OAP, but not the VAP and OpAP, showed the ideal relationship between the midsagittal and posterior maxillary plane, and properly described the different patterns of maxillofacial dysmorphology with craniofacial plane 1 of Delaire's analysis and the occlusal plane.

CONCLUSIONS

The proposed visual pathway-related horizontal reference planes, and in particular the OAP, seem to correctly express the visual axis and the position of the head in natural head position and can be used as a horizontal reference plane for the 3D analysis of craniofacial dysmorphology and anthropology.

The relationship between peripapillary crescent and axial length: Implications for differential eye growth

We evaluated the relationship between the size of the peripapillary crescent and the axial length (AL) of the eye as well as the fine structure of the peripapillary crescent in selected eyes. Infrared fundus imaging and spectral domain optical coherence tomography (SDOCT) (Spectralis HRA+OCT, Heidelberg Engineering, Germany) centered at the fovea were performed on 72 healthy adults. On the infrared fundus images, we measured (a) the distance between the foveola and the temporal edge of the optic disc (FOD) and (b) the distance between the foveola and the temporal edge of the peripapillary crescent (FOC) (if present). A peripapillary crescent presented at the nasal margin of the disc in 64% of the subjects. The FOD and FOC were 4.22mm±0.46 and 3.97mm±0.25, respectively. Only the FOD was significantly correlated with axial length. As AL increased by 10%, the FOD increased by 13%, the outer neural retina only expanded by 4% (as indicated by the FOC). This result emphasizes that retinal stretching may not mirror scleral growth, and the existence in some eyes of a difference between the photoreceptor margin and retinal pigment epithelium (RPE) margin suggests that within the retina there could be slippage during eye growth.

Peripapillary choroidal thickness in glaucoma measured with optical coherence tomography

As choroidal changes have been suggested in glaucoma, we examined peripapillary choroidal thickness (CT) in patients with and without primary open-angle glaucoma (POAG) using spectral-domain optical coherence tomography (SD-OCT). We collected measurements retrospectively on 70 eyes of 70 patients consecutively undergoing SD-OCT. POAG (n = 31) and suspect eyes (n = 39) had two reliable and repeatable Humphrey 24-2 visual fields with glaucoma hemifield test outside or within normal limits, respectively. A 360-degree peripapillary scan was performed using the standard protocol for retinal nerve fiber layer (RNFL) assessment. Using provided software, two independent masked investigators manually segmented CT as the area of visible choroidal vasculature. Agreement between investigators was determined using Lin's concordance correlation coefficient (CCC). A single masked observer determined clock hours of parapapillary atrophy (PPA) and the presence of ßPPA for each optic nerve quadrant. Correlation between RNFL and CT was assessed; two-sample t-tests were used to determine differences in RNFL and CT between POAG and suspect eyes; and linear regression was used to model changes in RNFL and CT. We found that independent measurements of CT by two observers were highly correlated (Lin's CCC for global CT; ρ(c) = 0.93, p < 0.001). RNFL and CT measurements were not significantly correlated for any peripapillary location (|r| ≤ 0.15, p ≥ 0.22). Global CT (ß = -1.94, 95% confidence interval [CI] -2.76, -1.13) but not RNFL thickness (ß = -0.18, 95% CI -0.58, 0.22) decreased significantly with age. Compared to suspect eyes, eyes with POAG had significantly thinner RNFL measurements at all locations (p ≤ 0.005) but CT measurements did not differ between groups for any location (p ≥ 0.13). Adjusting for glaucoma status and age, total (ß = 3.15 95% CI -0.24, 6.53) and ß clock hours of PPA (ß = 1.33, 95% CI -1.72, 4.38) were not significantly associated with global CT; the spatial distribution of PPA was not associated with underlying CT, though PPA was graded subjectively and may have been subject to spatial mismatch with a singular peripapillary eccentricity on SD-OCT. We conclude that eyes with POAG did not demonstrate reduced CT nor was there a correlation between RNFL and CT maps. This study does not support the use of CT assessment in glaucoma diagnosis or management.

Measuring normal ocular torsion and its variation by fundus photography in children between 5-15 years of age

Cycloposition has been measured by various methods; however, fundus photography is the most reliable method to evaluate the torsion objectively. We did a prospective study to find out the disc foveal angle (DFA) and its variation in children without squint. We included 210 eyes of 105 children between the ages of 5-15 years. DFA was calculated using standard technique after taking a fundus photograph. The cycloplegic refraction was done and compared. The mean age was 10.6 ± 2.5 years. Mean DFA in right eye (RE) was 6.49 ± 3.25° (0-13°) and in left eye (LE) was 5.80 ± 3.29° (0-12°). The difference between the RE and LE was statistically not significant (P=0.131) (mean 1.15 ±1.39°). Mean DFA in emmetropic children was 6.1° ± 3.4° (n=112 eyes). DFA varies widely in children. The difference observed in DFA measurement for eyes with various refractive errors were compared with DFA measurements for emmetropic eyes.

Spectral domain optical coherence tomographic characteristics of unilateral peripapillary myelinated retinal nerve fibers involving the macula

Unilateral, peripapillary, retinal nerve fiber myelination involving the macula, with optic disk hypoplasia, myopia, and amblyopia, is rare. We performed spectral domain optical coherence tomographic findings in 2 patients with this condition. Both patients had normal foveal morphology, reduced retinal thickness in the same distribution as the myelination, and optic nerve hypoplasia.

Progenitor cells of the rod-free area centralis originate in the anterior dorsal optic vesicle

Background

Nervous system development is dependent on early regional specification to create functionally distinct tissues within an initially undifferentiated zone. Within the retina, photoreceptors are topographically organized with rod free area centrales faithfully generated at the centre of gaze. How does the developing eye regulate this placement? Conventional wisdom indicates that the distal tip of the growing optic vesicle (OV) gives rise to the area centralis/fovea. Ectopic expression and ablation studies do not fully support this view, creating a controversy as to the origin of this region. In this study, the lineage of cells in the chicken OV was traced using DiI. The location of labelled cells was mapped onto the retina in relation to the rod-free zone at embryonic (E) 7 and E17.5. The ability to regenerate a rod free area after OV ablation was determined in conjunction with lineage tracing.

Results

Anterior OV gave rise to cells in nasal retina and posterior OV became temporal retina. The OV distal tip gave rise to cells above the optic nerve head. A dorsal and anterior region of the OV correlated with cells in the developing rod free area centralis. Only ablations including the dorsal anterior region gave rise to a retina lacking a rod free zone. DiI application after ablation indicated that cells movements were greater along the anterior/posterior axis compared with the dorsal/ventral axis.

Conclusion

Our data support the idea that the chicken rod free area centralis originates from cells located near, but not at the distal tip of the developing OV. Therefore, the hypothesis that the area centralis is derived from cells at the distal tip of the OV is not supported; rather, a region anterior and dorsal to the distal tip gives rise to the rod free region. When compared with other studies of retinal development, our results are supported on molecular, morphological and functional levels. Our data will lead to a better understanding of the mechanisms underlying the topographic organization of the retina, the origin of the rod free zone, and the general issue of compartmentalization of neural tissue before any indication of morphological differentiation.

Visual fields and optic disc morphology in very low birthweight adolescents examined with magnetic resonance imaging of the brain

PURPOSE

We aimed to evaluate visual fields (VFs) and optic disc morphology in very low birthweight (VLBW) adolescents compared with age- and gender-matched controls, and to relate the findings to magnetic resonance imaging (MRI) results.

METHODS

Fifty-nine VLBW adolescents and 55 age- and gender-matched controls with normal birthweight were examined. Visual fields were tested using computerized rarebit perimetry (RB). Optic nerve and retinal vessel morphology were evaluated by digital image analysis of fundus photographs. Brain MRI was conducted in the VLBW subjects.

RESULTS

Ten of the 57 VLBW subjects (p = 0.022) had subnormal VF results defined as a mean hit rate below the fifth percentile of the controls (i.e. < 89%). All of these also had significantly lower mean hit rates (p = 0.039) in the inferior hemifield. Sixteen of 57 (28%) VLBW subjects had white matter damage of immaturity (WMDI) on MRI. Six of 15 subjects with WMDI (who underwent VF testing) also had subnormal RB results, compared with four of 39 with normal MRI findings (p = 0.02). The mean neural retinal rim area was 9% smaller (p = 0.018) in the VLBW group than in the control group. The VLBW adolescents had a significantly higher index for tortuosity of arterioles than the controls (p < 0.001).

CONCLUSIONS

In the present study, 18% of all VLBW adolescents and 40% of those with WMDI had subnormal RB VF findings. The VLBW group had increased arterial tortuosity and a somewhat smaller (9%) mean neural retinal rim area than the control group. Thus sequels to VLBW appear to persist in adolescence.

Calibration of fundus images using spectral domain optical coherence tomography

BACKGROUND AND OBJECTIVE

Measurements performed on fundus images using current software are not accurate. Accurate measurements can be obtained only by calibrating a fundus camera using measurements between fixed retinal landmarks, such as the dimensions of the optic nerve, or by relying on a calibrated model eye provided by a reading center. However, calibrated spectral domain OCT (SD-OCT) could offer a convenient alternative method for the calibration of any fundus image.

PATIENTS AND METHODS

The ability to measure exact distances on SD-OCT fundus images was tested by measuring the distance between the center of the fovea and the optic nerve. Calibrated SD-OCT scans measuring 6 X 6 X 2 mm centered on the fovea and the optic nerve were analyzed in 50 healthy right eyes. The foveal center was identified using cross-sectional SD-OCT images, and the center of the optic nerve was identified manually. The SD-OCT scans were registered to each other, and the distances between the center of the optic nerve and fovea were calculated. The overlay of these SD-OCT fundus images on photographic fundus images was performed.

RESULTS

Any image of the fundus could be calibrated by overlaying the SD-OCT fundus image, and the measurements were consistent with previously defined calibration methods. The mean distance between the center of the fovea and the center of the optic nerve was 4.32 +/-0.32 mm. The line from the center of the optic nerve to the foveal center had a mean declination of 7.67 +/- 3.88 degrees. Mean horizontal displacement and vertical displacement were 4.27 +/- 0.29 mm and 0.58 +/- 0.29 mm, respectively.

CONCLUSIONS

The overlay of the SD-OCT fundus image provides a convenient method for calibrating any image of the fundus. This approach should provide a uniform standard when comparing images from different devices and from different reading centers.

Visual Acuity and Fixation Characteristics in Age-Related Macular Degeneration

PURPOSE

To compare "single letter" (SL) acuity, "crowded letter" (CL) acuity, and "repeated letter" (RL) acuity for patients with age-related macular degeneration (AMD) and investigate if differences between these visual acuities are associated with fixation characteristics.

METHODS

A total of 243 patients with AMD had their best-corrected visual acuity measured on an ETDRS chart. SL, CL, and RL acuities were measured using Landolt C targets on a monitor. Fifty-degree-field red-free fundus photographs were taken and a static target was used to calculate the Preferred Retinal Locus (PRL) distance and direction from the fovea. Quality of fixation (consistency and oculomotor response) was also assessed using a fundus camera and a dynamic target.

RESULTS

RL acuity was almost always better than CL acuity and SL acuity was almost always better than CL acuity. The mean (+/-SD) RL-CL and SL-CL acuity differences were -0.13 (+/-0.15) logMAR and -0.11 (+/-0.13) logMAR respectively. The median PRL distance was 3.73 degrees and the preferred retinal areas for the location of the PRL were the left (left quadrant of visual field; 39.5% of cases) and superior (inferior quadrant of visual field; 25.4%). Visual acuity was significantly associated with PRL distance but PRL distance only explained 10% of the variation in visual acuity. PRL distance was found to be a significant but weak predictor of the SL-CL acuity difference but fixation quality was not a good predictor of the RL-CL acuity difference.

CONCLUSIONS

Although the acuity measured under different stimulus conditions varies, the absolute differences are small. This suggests that these techniques would not be helpful in determining fixation characteristics, or predicting the outcome of rehabilitation in individual patients with AMD.

The temporal retinal vessel angle and infants born preterm

AIM

To determine the temporal retinal vessel angle in babies and its relation to preterm birth.

METHODS

Digital images were obtained during routine screening for retinopathy of prematurity (ROP). The temporal retinal vessel angle was measured in 164 eyes of 82 babies born "very preterm" (24-27 weeks gestational age (GA)), "preterm" (28-31 weeks GA), and "near term" (>/=32 weeks GA).

RESULTS

Mean temporal vessel angle (TVA) for all three GA groups together is 80.0 degrees (SD 17.0 degrees ) for the right eye and 80.5 degrees (16.7 degrees ) for the left eye. The range is right eye 59-106 degrees , left eye 69-97 degrees , with 95% data above 67 degrees for the right and 63 degrees for the left eye. For babies born near term, TVA is 82 degrees in each eye. There is a high degree of interocular symmetry between right and left eyes and a statistically insignificant trend for increasing TVA with increasing GA. The presence and stage of ROP affected one parameter of the left eye alone.

CONCLUSIONS

These data provide normative data on the TVA in babies and will facilitate, especially if there is interocular asymmetry, determining whether there is macular displacement.

Optic chiasm formation in humans is independent of foveal development

A failure of human foveal development only occurs in two genetically determined conditions; aniridia (Pax6 mutation) and albinism (tyrosinase mutation). The chiasmatic pathways from this region are disrupted in albinism and central retinal blood vessel patterns are abnormal. It is assumed that these three abnormalities have a common mechanism. Here we investigate whether similar abnormalities are present in subjects with aniridia. Using fundus photographs it is shown that abnormal blood vessel patterns are present in aniridia, but these significantly differ from those in albinos. Using electrophysiological techniques, abnormal hemispheric projections through the chiasm are demonstrated in albinos, but aniridics do not differ from normal subjects. These results demonstrate that although mutations in Pax6 and tyrosinase both affect central retinal development, they have a fundamentally different impact on the formation of the retinal vasculature and the projections from this region. This strongly suggests that separate mechanisms regulate the development of the central retina and decussation patterns at the optic chiasm.

Retinal location of the preferred retinal locus relative to the fovea in scanning laser ophthalmoscope images

PURPOSE

It is difficult to determine the position of a preferred retinal locus (PRL) relative to the fovea in scanning laser ophthalmoscope (SLO) images as a result of disease-related retinal morphologic changes that obscure the fovea. To overcome this problem, we developed a method for determining retinal foveal position based on normal fixation position relative to the optic disk. The normal foveal position measurements can then be used to estimate the distance between a PRL and the fovea.

METHODS

Using the SLO, foveal position was determined for 50 normal subjects by measuring the retinal locus of fixation relative to the optic disk in undistorted SLO images. The resulting normal foveal fixation area is described by a bivariate normal ellipse that can be plotted on any undistorted SLO image. Measurement reliability was assessed by repeated measurements. The PRL relative to the normal foveal fixation area was determined for 24 subjects with macular degeneration and bilateral central scotomas.

RESULTS

The normal foveal fixation area based on all 50 subjects is described by a p = 0.9 bivariate ellipse whose centroid is located 12.6 degrees temporal to the temporal optic disk edge and 1.4 degrees inferior to a horizontal line bisecting the disk. PRL area is shown to increase with distance from the foveal fixation ellipse centroid. The shape of the PRL, characterized by the ratio of PRL ellipse major to minor axis, was found to depend on whether the PRL was vertically or horizontally aligned with the foveal fixation centroid.

CONCLUSIONS

PRL position relative to the fovea can be reliably estimated by plotting the normal foveal fixation bivariate ellipse on undistorted SLO images of retinas in which the fovea is obscured as a result of the disease process.

Senescence of human multifocal electroretinogram components: a localized approach

BACKGROUND

Previous studies have shown significant age-related changes in the first-order kernel of multifocal ERG (mfERG) responses. All of these reports were based upon ring averages across the retinal field. This study was carried out to determine age-related changes in the localized response and localized variability in the mfERG parameters: N1P1 amplitude, scalar product and implicit time of P1.

METHODS

MfERG recordings from 70 normal phakic subjects (ages 9-80 years) were analyzed with VERIS 4.8. Scalar product values (for each hexagon based on ring average templates) were obtained and analyzed for age-related changes. Statistical measures such as coefficient of variation (CV) and parameters of a linear regression model were applied. Point-by-point comparisons were made across hemifields.

RESULTS

Each localized response showed a significant aging effect either in scalar product or in N1P1 amplitude. The average decline of the response was approximately 5% per decade, varying from 3.3% (peripherally) to 7.5% (perifoveally). The decline was significantly higher for the superior than for the inferior retina for amplitude parameters, corresponding to larger increases in P1 implicit time. The relative rate of change with age was similar for the nasal and the temporal retina. The average CV for all subjects at all locations was 29.4% (+/-4.1%).

CONCLUSIONS

The localized approach revealed patterns of age-related change that were not apparent in the ring averages. Information about changes in discrete retinal areas with age should make the mfERG more useful in quantitatively monitoring progression of retinal disease.

Foveal ectopia in X-linked retinoschisis

BACKGROUND

This study compared the position of the foveal center in patients with X-linked retinoschisis (XLRS) and controls and estimated the frequency of foveal ectopia in XLRS.

METHOD

Fundus photographs of 23 patients with XLRS and 25 controls were reviewed. The position of the foveal center relative to the vertical center of the optic disk was determined from magnified images and expressed as the angle between the disk and foveal centers, relative to the horizontal meridian. The shortest distance between the foveal and disk centers was also measured, using the horizontal disk diameter (HDD) as the relative size unit.

RESULTS

The position of the foveal center could be determined accurately for 43 eyes of the 23 patients with XLRS. The foveal center was located an average of 4.7 degrees (standard deviation, 9.3) below and 3.2 HDD (standard deviation, 0.4) temporal to the vertical disk center. In 9 (21 %) of the eyes, the fovea was above the horizontal meridian. For the control eyes, the foveal center was an average of 7.8 degrees (standard deviation, 2.3) below and 2.9 HDD (standard deviation, 0.4) temporal to the vertical disk center. According to a previous definition, foveal ectopia was present in 13 (30%) of the eyes with XLRS and none of the control eyes (P < 0.001).

CONCLUSION

Foveal ectopia occurs in at least 30% of eyes with XLRS. This finding may provide a useful diagnostic sign for XLRS and may have implications for its pathogenesis.