Spectral domain optical coherence tomographic findings at convalescent stage of acute zonal occult outer retinopathy

Progression of Anterograde Trans-Synaptic Degeneration in the Human Retina Is Modulated by Axonal Convergence and Divergence

In the visual pathway of patients with multiple sclerosis (MS), the inner nuclear layer (INL) of the retina is a tight barrier for retrograde trans-synaptic degeneration. In this observational, retrospective cross-sectional study, segmented macular spectral domain optical coherence tomography (OCT) volume scans were reviewed to investigate if this observation also holds true for anterograde trans-synaptic degeneration. Significant thinning was found in all retinal layers in patients with outer retinal diseases compared with the healthy controls, while there was no significant attenuation of the outer retina in patients with MS. In contrast to the tight barrier function observed with retrograde trans-synaptic degeneration, the INL appears to be more permissive for the propagation of anterograde trans-synaptic degeneration. We speculate that this may be due to the size of the area affected and be explained by convergence and divergence of axons within the retinal layers. These findings are likely relevant to future restorative stem cell treatment of the outer retinal layers, as time may matter.

ACUTE ZONAL OCCULT OUTER RETINOPATHY: Structural and Functional Analysis Across the Transition Zone Between Healthy and Diseased Retina

PURPOSE

To assess structure and function across the transition zone (TZ) between relatively healthy and diseased retina in acute zonal occult outer retinopathy.

METHODS

Six patients (6 eyes; age 22-71 years) with acute zonal occult outer retinopathy were studied. Spectral-domain optical coherence tomography, fundus autofluorescence, near-infrared reflectance, color fundus photography, and fundus perimetry were performed and images were registered to each other. The retinal layers of the spectral-domain optical coherence tomography scans were segmented and the thicknesses of two outer retinal layers, that is, the total receptor and outer segment plus layers, and the retinal nerve fiber layer were measured.

RESULTS

All eyes showed a TZ on multimodal imaging. On spectral-domain optical coherence tomography, the TZ was in the nasal retina at varying distances from the fovea. For all eyes, it was associated with loss of the ellipsoid zone band, significant thinning of the two outer retinal layers, and in three eyes with thickening of the retinal nerve fiber layer. On fundus autofluorescence, all eyes had a clearly demarcated peripapillary area of abnormal fundus autofluorescence delimited by a border of high autofluorescence; the latter was associated with loss of the ellipsoid zone band and with a change from relatively normal to markedly decreased or nonrecordable visual sensitivity on fundus perimetry.

CONCLUSION

The results of multimodal imaging clarified the TZ in acute zonal occult outer retinopathy. The TZ was outlined by a distinct high autofluorescence border that correlated with loss of the ellipsoid zone band on spectral-domain optical coherence tomography. However, in fundus areas that seemed healthy on fundus autofluorescence, thinning of the outer retinal layers and thickening of the retinal nerve fiber layer were observed near the TZ. The TZ was also characterized by a decrease in visual sensitivity.

Ellipsoid zone on optical coherence tomography: a review

Emergence of the high-resolution optical coherence tomography has allowed better delineation of retinal layers, and many of the anatomical correlations of these layers have now been agreed upon. However, some anatomical correlates still remain contentious, such as the second hyper-reflective band, which is now termed ellipsoid zone. Despite the lack of consensus of the actual origin of the ellipsoid zone, there has been much interest in evaluating its integrity and intensity in different disease processes. This review paper aims to provide an overview of the ellipsoid zone and its clinical and research applications.

Functional and anatomic changes in acute multifocal placoid pigment epitheliopathy: a case report

PURPOSE

To report the functional and anatomic features of a case of acute posterior multifocal placoid pigment epitheliopathy (APMPPE).

METHODS

Case report.

RESULTS

A 30-year-old man presented with a decrease of visual acuity that started a few days earlier. Fundus examination showed multiple, subretinal, white-yellowish lesions at the posterior pole in both eyes, suggesting APMPPE. Symptoms and clinical signs resolved within a few weeks, leaving well-defined areas of atrophy of the retinal pigment epithelium (RPE).

CONCLUSIONS

This case report emphasizes the role of the RPE in the pathogenesis of APMPPE.

Changes in optical coherence tomography findings in acute zonal occult outer retinopathy

Purpose

To report a case of acute zonal occult outer retinopathy (AZOOR) in a 39-year-old woman.

Methods

Images were obtained with fundus photography and optical coherence tomography (OCT). A multifocal electroretinogram (mfERG) was also obtained to evaluate retinal function.

Results

The patient's right visual acuity was 0.8. Fundus photographs showed no specific abnormal findings. OCT showed attenuation of the photoreceptor inner segment/outer segment (IS/OS) line and the cone outer segment tip (COST) line in the right eye. The mfERG showed corresponding amplitude reductions. One month after the initial visit, her right visual acuity improved to 1.2. There was partial recovery of the IS/OS line; however, the COST line was still absent, and there was no apparent improvement in the mfERG responses.

Conclusions

Our findings showed a discrepancy between the microstructural findings and visual function during recovery of AZOOR.

An optical coherence tomography and fundus autofluorescence imaging study of peripapillary acute zonal occult outer retinopathy

PURPOSE

To evaluate peripapillary acute zonal occult outer retinopathy in a 67-year-old man.

METHODS

Images were obtained using fundus photography, fluorescein angiography (FA) and indocyanine green angiography (ICGA), fundus autofluorescence (FAF) imaging, and optical coherence tomography (OCT). Visual field testing and multifocal electroretinogram (mfERG) were also performed to evaluate retinal function.

RESULTS

Fundus photographs showed subtle pigmentary changes in the peripapillary region, while FAF imaging showed clearly defined hypofluorescent areas in the peripapillary region. Intense hyperfluorescent lesions were also seen underneath hypofluorescent areas. A transmission defect with a granular hyperfluorescence was visible on FA, and ICGA showed hypofluorescence within the lesion. The outer border of the peripapillary zone appeared to block the underlying choroidal fluorescence. The photoreceptor inner segment/outer segment line was absent on OCT images from this area in both eyes, and hyperreflective punctate drusen-like materials were present at the outer border of the peripapillary zone. Visual field testing by Goldmann perimetry showed blind-spot enlargement, and mfERG showed corresponding amplitude reductions.

CONCLUSIONS

We speculate that the intense hyperautofluorescent material at the outer border of the peripapillary zone might be accumulated drusenoid lipofuscin.

Case of unilateral peripheral cone dysfunction

Purpose

Peripheral cone dystrophy is a subgroup of cone dystrophy, and only 4 cases have been reported. We present a patient with unilateral peripheral cone dysfunction and report the functional changes determined by electrophysiological tests and ultrastructural changes determined by spectral domain optical coherence tomography (SD-OCT).

Case

A 34-year-old woman complained of blurred vision in both eyes. Our examination showed that her visual acuity was 0.05 OD and 0.2 OS. A relative afferent pupillary defect was present in her right eye. The results of slit-lamp examination, ophthalmoscopy, and fluorescein angiography were normal except for pallor of the right optic disc. SD-OCT showed a diffuse thinning of the retina in the posterior pole of the right eye. A severe constriction of the visual fields was found in both eyes but more in the right eye. The photopic full-field electroretinograms (ERGs) were reduced in the right eye but normal in the left eye. The multifocal ERGs were severely reduced throughout the visual field except in the central area of the right eye. The multifocal ERGs from the left eye were normal. The pattern visual evoked responses were within the normal range in both eyes. She had a 5-year history of sniffing paint thinner.

Results

Although the visual dysfunction was initially suspected to be due to psychological problems from the results of subjective tests, objective tests indicated a peripheral cone dysfunction in the right eye. The pathophysiological mechanism and the relationship with thinner sniffing were not determined.

Conclusions

Our findings indicate that peripheral cone dysfunction can occur unilaterally. Electrophysiology and SD-OCT are valuable tests to perform to determine the pathogenesis of unusual ocular findings objectively.

Abnormal multifocal ERG findings in patients with normal-appearing retinal anatomy

To evaluate eyes with abnormal visual fields and multifocal electroretinograms (mfERGs) but normal-appearing frequency-domain optical coherence tomography (fdOCT) scans, the thicknesses of the outer retinal layers were measured. A total of 25 eyes from 17 patients, including 15 eyes previously tested (Dale et al. in Doc Ophthalmol 120(2):175-186, 2009) were examined. All patients were evaluated with standard automated perimetry (SAP) using the 24-2 and/or 10-2 program (Zeiss Meditec), mfERG with 103 hexagons (Veris, EDI), and fdOCT imaging (3DOCT-2000, Topcon) with scans of the macula. All patients had reliable visual fields showing macular defects and good quality mfERG and fdOCT results. The mfERG results were classified as abnormal based on decreased amplitudes and/or increased latencies corresponding to the abnormal visual field. Based on visual inspection, three experienced observers classified the fdOCT scans as normal or inconclusive, as opposed to clearly abnormal. Retinal layers of the fdOCT scans were manually segmented with the aid of a computer program and compared to mean thicknesses from 20 controls. The thicknesses of the outer segment plus retinal pigment epithelium, total receptor, and inner nuclear layers were measured. Quantitative analysis of fdOCT scans demonstrated thinning of the outer retina in some scans that was not readily apparent on visual inspection. One or more of the outer retinal layers was significantly thinner in 15 of the 25 eyes. The absence of significant thinning in the other 10 eyes represents instances in which functional loss measured by visual fields and mfERGs can precede clear structural changes on fdOCT.

Focal functional and microstructural changes of photoreceptors in eyes with acute zonal occult outer retinopathy

PURPOSE

Acute zonal occult outer retinopathy (AZOOR) is characterized by an acute zonal loss of outer retinal function with minimal ophthalmoscopic changes in one or both eyes. We present a patient with AZOOR whose ultrastructural and functional findings were followed for 8 months.

CASE

A 22-year-old woman developed an acute central scotoma in her right eye. Her best-corrected visual acuity (BCVA) was 0.5 OD and 1.2 OS. The ophthalmoscopic examinations, fluorescein angiography, and full-field electroretinograms (ERGs) were normal in both eyes. The amplitudes of the multifocal ERGs (mfERGs) were attenuated in the area corresponding to the scotoma. Spectral domain optical coherence tomography showed an absence of both the inner and outer segment (IS/OS) line of the photoreceptors and the cone outer segment tip (COST) line between the IS/OS line and the retinal pigment epithelium. These changes were seen in the area corresponding to the scotoma. One month later, the scotoma disappeared and the BCVA improved to 1.2 OD. The mfERGs increased to almost the same amplitude as the fellow eye. The IS/OS line became discernible but the COST line was still absent. The ophthalmological findings of the right macula remained normal during the 11-month follow-up period.

CONCLUSIONS

Our findings indicate that the selective loss of the IS/OS and the COST lines is probably the morphological alterations corresponding with the reduced BCVA and the mfERGs in the areas of the visual field defects in the acute phase of AZOOR. But in the recovery phase, only the abnormality of the COST line is a subclinical sign for the disease. These findings should be important in understanding and evaluating the pathological mechanism in other outer retinal diseases.

Outer retinal microstructure in a case of acute idiopathic blind spot enlargement syndrome

Purpose

To present a patient with acute idiopathic blind spot enlargement syndrome who had abnormal changes in the outer retinal microstructure limited to areas with reduced responses on multifocal electroretinograms as well as to the area involving a scotoma.

Methods and Results

We report the case of a 44-year-old man who developed an arcuate scotoma which was associated with a physiological blind spot in the left eye. The ophthalmoscopic, fluorescein angiographic, and full-field electroretinogram findings were normal. The amplitudes of the multifocal electroretinograms were reduced in the area of the scotoma. Optical coherence tomography showed that both the external limiting membrane and the inner and outer segment (IS/OS) line were intact, but that the middle cone outer segment tip line between the IS/OS line and the retinal pigment epithelium was absent in the nasal macular area of the left eye.

Conclusions

These findings indicate that the integrity of not only the external limiting membrane and IS/OS line but also the cone outer segment tip line is important for the function of the retina.