En face optical coherence tomography of foveal microstructure in full-thickness macular hole: a model to study perifoveal Müller cells

Müller cell vulnerability in aging human retina: Implications on photoreceptor cell survival

Müller glial cells (MC) support various metabolic functions of the retinal neurons, and maintain the homeostasis. Oxidative stress is intensified with aging, and in human retina, MC and photoreceptors undergo lipid peroxidation and protein nitration. Information on how MC respond to oxidative stress is vital to understand the fate of aging retinal neurons. This study examined age-related changes in MC of donor human retina (age: 35-98 years; N = 18 donors). Ultrastructural and immunohistochemical observations indicate that MC undergo gliosis and increased lipid peroxidation, and show osmotic changes with advanced aging (>80 years). Photoreceptor cells also undergo oxidative-nitrosative stress with aging, and their synapses also show clear osmotic swelling. MC respond to oxidative stress via proliferation of smooth endoplasmic reticulum in their processes, and increased expression of aquaporin-4 in endfeet and outer retina. In advanced aged retinas (81-98 years), they showed mitochondrial disorganisation, accumulation of lipids and autophagosomes, lipofuscin granules and axonal remnants in phagolysosomes in their inner processes, suggesting a reduced phagocytotic potential in them with aging. Glutamine synthetase expression does not alter until advanced aging, when the retinas show its increased expression in endfeet and Henle fiber layer. It is evident that MC are vulnerable with normal aging and this could be a reason for photoreceptor cell abnormalities reported with aging of the human retina.

Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose

Microcystic macular edema (MME), also known as retrograde maculopathy (RM), is associated with severe optic atrophy because of a range of causes. However, similar changes have also been described in primary retinal pathology and the pathogenesis of MME is debated.

Design

A retrospective observational case series.

Participants

Patients with nonarteritic ischemic optic neuropathy.

Methods

A retrospective observational case series was performed at the University Hospital of Liège, Belgium. The medical records of patients who were referred to our Neuro-ophthalmology department with a diagnosis of nonarteritic anterior ischemic optic neuropathy (NA-AION), between 2014 and 2021, were reviewed.

Main Outcome Measures

Ganglion cell complex thickness, acute and chronic inner nuclear change.

Results

In a cohort of 34 patients (mean age: 60 ± 12.5 years; 65.6% men) with NA-AION, we identified a transient microcystic change in the inner nuclear layer (INL) associated with optic disc swelling in 19 eyes at presentation. This early change was associated with a transudate of intraretinal and subretinal fluid originating from the optic disc. Among patients who had shown this transient change 3 subsequently developed MME, which remained fixed during the period of observation (range, 12–34 months). No MME was observed in patients without an early INL transient change. Microcystic macular edema was observed in patients with severe ganglion cell complex thinning at 6 months: mean (± SD) loss in superior hemimacula (−28.2 ± 5.2 μm [−33.3%, range, −22.3 to −30.3 μm]) and in inferior hemimacula (−30.7 ± 5.6 μm [−31.0%, range, −24.3 to 34.8 μm]).

Conclusions

Our study has revealed 2 causes of INL cystic change in the same patients experiencing NA-AION, 1 reversible and the other likely permanent. This finding highlights the distinction between genuine edema related to transudation of fluid (in this case secondary to ischemic optic disc swelling) and the phenomenon observed in RM that is related to the degree of retinal nerve fiber layer/ganglion cell complex thinning. Cystic change in the INL is associated with severe optic atrophy (MME). However, similar changes have been described in retinal pathology and the pathogenesis of MME is debated.

Surgical classification for large macular hole: based on different surgical techniques results: the CLOSE study group

BACKGROUND

The CLOSE study group proposes an updated surgical classification for large macular holes based on a systematic review of new treatments. Recently, many new techniques have been introduced to treat large full-thickness macular holes (FTMH); although the indications are not clear. An updated surgical classification is needed to help surgical decision-making.

METHODS

We gathered published series by the CLOSE Study Group members and from literature search until June 2021. Techniques included: internal limiting membrane peeling (ILM peeling), ILM flaps, macular hydrodissection (macular hydro), human amniotic membrane graft (hAM), and autologous retinal transplantation (ART). Within each technique, chi-square test assessed association between the minimal linear diameter (MLD) (in µm) and closure rate; the postoperative best-corrected visual acuity (BCVA) gains were compared among groups.

RESULTS

Data extraction included 31 published articles: total of 1135 eyes. Eyes were divided into the following groups: ILM peel (n: 683), ILM Flap (n: 233), macular hydrodissection (n: 64), hAM (n: 59), and ART (n: 96). The initial BCVA and size were heterogenous between the groups. ILM peel showed the best results in large FTMH ≤ 535 µm (closure rate 96.8%); adjusted mean BCVA: 0.49 (LogMAR) with a statistical difference among groups. Large FTMH between 535 and 799 µm: ILM flap technique showed better results (closure rate 99.0%); adjusted mean BCVA: 0.67(LogMAR); also with a statistical difference. For large FTMH ≥ 800 µm more invasive techniques are required. Use of hAM, macular hydrodissection and ART showed higher closure rates for this category (100%, 83.3% and 90.5% respectively), and adjusted mean BCVA varied from 0.76 to 0.89. Although there was no statistical difference between those techniques for this group due to the smaller number of cases.

CONCLUSIONS

The CLOSE study group demonstrated the potential usefulness of a new surgical classification for large FTMHs and propose OCT biomarkers for use in clinical practice and future research. This new classification demonstrated that Large (400-550 µm) and X-Large (550-800 µm) holes can be treated highly successfully with ILM peel and ILM flap techniques, respectively. Further studies are necessary for the larger FTMHs (XX-Large and Giant), using the CLOSE classification, in order to determine which technique is better suited for each hole size and characteristics.

Retinal thickness changes in different subfields reflect the volume change of cerebral white matter hyperintensity

Purpose

To investigate the relationship between the retinal thickness in different subfields and the volume of white matter hyperintensity (WMH), with the hope to provide new evidence for the potential association between the retina and the brain.

Methods

A total of 185 participants aged over 40 years were included in our study. Magnetic resonance imaging (MRI) was used to image the WMH, and WMH volume was quantitatively measured by a specific toolbox. The thickness of the total retina, the retinal nerve fiber layer (RNFL), and the ganglion cell and inner plexiform layer (GCIP) was measured by optical coherence tomography (OCT) in nine subfields. The association between retinal thickness and WMH volume was demonstrated using binary logistic regression and Pearson correlation analysis.

Results

Participants were divided into two groups by the WMH volume (‰, standardized WMH volume) median. In the quartile-stratified binary logistic regression analysis, we found that the risk of higher WMH volume showed a positive linear trend correlation with the thickness of total retina (95% CI: 0.848 to 7.034; P for trend = 0.044)/ GCIP (95% CI: 1.263 to 10.549; P for trend = 0.038) at the central fovea, and a negative linear trend correlation with the thickness of nasal inner RNFL (95% CI: 0.086 to 0.787; P for trend = 0.012), nasal outer RNFL (95% CI: 0.058 to 0.561; P for trend = 0.004), and inferior outer RNFL (95% CI: 0.081 to 0.667; P for trend = 0.004), after adjusting for possible confounders. Correlation analysis results showed that WMH volume had a significant negative correlation with superior outer RNFL thickness (r = −0.171, P = 0.02) and nasal outer RNFL thickness (r = −0.208, P = 0.004).

Conclusion

It is suggested that central fovea and outer retina thickness are respectively associated with WMH volume. OCT may be a biological marker for early detection and longitudinal monitoring of WMH.

WFS1-Associated Optic Neuropathy: Genotype-Phenotype Correlations and Disease Progression

OBJECTIVE

To evaluate the pattern of vision loss and genotype-phenotype correlations in WFS1-associated optic neuropathy (WON).

DESIGN

Multicenter cohort study.

METHODS

The study involved 37 patients with WON carrying pathogenic or candidate pathogenic WFS1 variants. Genetic and clinical data were retrieved from the medical records. Thirteen patients underwent additional comprehensive ophthalmologic assessment. Deep phenotyping involved visual electrophysiology and advanced psychophysical testing with a complementary metabolomic study.

MAIN OUTCOME MEASURES

WFS1 variants, functional and structural optic nerve and retinal parameters, and metabolomic profile.

RESULTS

Twenty-two recessive and 5 dominant WFS1 variants were identified. Four variants were novel. All WFS1 variants caused loss of macular retinal ganglion cells (RGCs) as assessed by optical coherence tomography (OCT) and visual electrophysiology. Advanced psychophysical testing indicated involvement of the major RGC subpopulations. Modeling of vision loss showed an accelerated rate of deterioration with increasing age. Dominant WFS1 variants were associated with abnormal reflectivity of the outer plexiform layer (OPL) on OCT imaging. The dominant variants tended to cause less severe vision loss compared with recessive WFS1 variants, which resulted in more variable phenotypes ranging from isolated WON to severe multisystem disease depending on the WFS1 alleles. The metabolomic profile included markers seen in other neurodegenerative diseases and type 1 diabetes mellitus.

CONCLUSIONS

WFS1 variants result in heterogenous phenotypes influenced by the mode of inheritance and the disease-causing alleles. Biallelic WFS1 variants cause more variable, but generally more severe, vision and RGC loss compared with heterozygous variants. Abnormal cleftlike lamination of the OPL is a distinctive OCT feature that strongly points toward dominant WON.

Ocular Barriers and Their Influence on Gene Therapy Products Delivery

The eye is formed by tissues and cavities that contain liquids whose compositions are highly regulated to ensure their optical properties and their immune and metabolic functions. The integrity of the ocular barriers, composed of different elements that work in a coordinated fashion, is essential to maintain the ocular homeostasis. Specialized junctions between the cells of different tissues have specific features which guarantee sealing properties and selectively control the passage of drugs from the circulation or the outside into the tissues and within the different ocular compartments. Tissues structure also constitute selective obstacles and pathways for various molecules. Specific transporters control the passage of water, ions, and macromolecules, whilst efflux pumps reject and eliminate toxins, metabolites, or drugs. Ocular barriers, thus, limit the bioavailability of gene therapy products in ocular tissues and cells depending on the route chosen for their administration. On the other hand, ocular barriers allow a real local treatment, with limited systemic side-effects. Understanding the different barriers that limit the accessibility of different types of gene therapy products to the different target cells is a prerequisite for the development of efficient gene delivery systems. This review summarizes actual knowledge on the different ocular barriers that limit the penetration and distribution of gene therapy products using different routes of administration, and it provides a general overview of various methods used to bypass the ocular barriers.

Retinal displacement and intraretinal structural changes after idiopathic macular hole surgery

PURPOSE

To investigate the correlations of thickness of three retinal layers with retinal displacement after idiopathic macular hole surgery.

STUDY DESIGN

Retrospective, consecutive, case series.

METHODS

42 eyes of 42 patients undergoing macular hole surgery with internal limiting membrane peeling were studied. Retinal distance was measured with near-infrared images between the optic nerve and the intersection of retinal vessels at four quadrants. Retinal thicknesses of inner retinal layer, inner nuclear layer and outer retinal layer were measured 1000 μm away from the central fovea using Spectralis.

RESULTS

Retinal distances other than the nasal quadrant decreased postoperatively (p < 0.001). Retinal displacement (%) correlated significantly with the change in inner nuclear layer thickness in the temporal sector at 1, 3, and 6 months, in the superior sector at 2 weeks, 1, and 6 months, and in the inferior sector at 3 and 6 months postoperatively (r = 0.319-0.570, p < 0.001-0.040), but not in the inner or outer retinal layers.

CONCLUSION

Internal limiting membrane peeling for macular hole enhances retinal displacement toward the optic disc, whose distances correlate with the changes in inner nuclear layer thickness.

EFFECT OF LASER PHOTOCOAGULATION ON MACULAR EDEMA ASSOCIATED WITH MACULAR HOLES

PURPOSE

To report the outcomes of laser therapy to barricade eccentric full-thickness macular hole with associated cystoid macular edema.

METHODS

We report two patients who developed an eccentric full-thickness macular hole with persistent cystoid macular edema after pars plan vitrectomy with and without internal limiting membrane peel for epiretinal membrane and the results of argon laser therapy.

RESULTS

Barricade argon laser therapy was applied concentric to the full-thickness macular hole. Associated cystoid macular edema was noted to resolve within 1 to 3 months of therapy in both cases.

CONCLUSION

Barricade laser therapy surrounding a macular hole can lead to resolution of associated cystoid macular edema. Pathogenic mechanisms to explain this favorable outcome are discussed.

Stellate nonhereditary idiopathic foveomacular retinoschisis resolution after vitreomacular adhesion release

PURPOSE

To present a case of stellate nonhereditary idiopathic foveomacular retinoschisis (SNIFR) resolution associated with vitreomacular adherence (VMA) release and propose a potential contributing association between SNIFR and vitreomacular interactions.

OBSERVATIONS

A 67-year-old female patient was diagnosed and followed for SNIFR in OD with spectral-domain optical coherence tomography (SD-OCT) scans at presentation and subsequent visits at 3, 6, 16 and 22 months. VMA and foveomacular retinoschisis remained unchanged on SD-OCT during the first 6 months of the follow-up. At 16-month follow-up visit, SD-OCT revealed VMA release and an important improvement of the macular schisis. At 22 months of follow-up, SNIFR cavities completely resolved in the presence of posterior hyaloid separation from the macular area without any adjunct treatment. The authors could not identify any other possible cause to justify the resolution of SNIFR other than VMA release in this case. Patient did not undergo any treatment for OD other than phacoemulsification 3 months after initial visit.

CONCLUSION

The present case illustrates with SD-OCT scans a possible association between SNIFR resolution and VMA release, highlighting a potential tractional component of the posterior vitreous on the internal limiting membrane and consequent glial cells stretching with schisis formation.

Hyperreflective Foci, Optical Coherence Tomography Progression Indicators in Age-Related Macular Degeneration, Include Transdifferentiated Retinal Pigment Epithelium

Purpose

By optical coherence tomography (OCT) imaging, hyperreflective foci (HRF) indicate progression risk for advanced age-related macular degeneration (AMD) and are in part attributable to ectopic retinal pigment epithelium (RPE). We hypothesized that ectopic RPE are molecularly distinct from in-layer cells and that their cross-retinal course follows Müller glia.

Methods

In clinical OCT (61 eyes, 44 patients with AMD, 79.4 ± 7.7 years; 29 female; follow-up = 4.7 ± 0.9 years), one HRF type, RPE plume (n = 129 in 4 morphologies), was reviewed. Twenty eyes of 20 donors characterized by ex vivo OCT were analyzed by histology (normal, 4; early/intermediate AMD, 7; geographic atrophy, 6; neovascular AMD, 3). Cryosections were stained with antibodies to retinoid (RPE65, CRALPB) and immune (CD68, CD163) markers. In published RPE cellular phenotypes, red immunoreactivity was assessed semiquantitatively by one observer (none, some cells, all cells).

Results

Plume morphology evolved over time and many resolved (40%). Trajectories of RPE plume and cellular debris paralleled Müller glia, including near atrophy borders. RPE corresponding to HRF lost immunoreactivity for retinoid markers and gained immunoreactivity for immune markers. Aberrant immunoreactivity appeared in individual in-layer RPE cells and extended to all abnormal phenotypes. Müller glia remained CRALBP positive. Plume cells approached and contacted retinal capillaries.

Conclusions

HRF are indicators not predictors of overall disease activity. Gain and loss of function starts with individual in-layer RPE cells and extends to all abnormal phenotypes. Evidence for RPE transdifferentiation, possibly due to ischemia, supports a proposed process of epithelial–mesenchyme transition. Data can propel new biomarkers and therapeutic strategies for AMD.

Intraretinal Cysts in Macular Hole: A Structure-Function Correlation Based on En Face Imaging

Purpose

To characterize retinal micromorphic changes on en face optical coherence tomography (OCT) and to determine their role in pathogenesis and visual outcomes in macular hole (MH) surgery.

Patients and Methods

This is a retrospective, interventional, consecutive case series of 28 eyes undergoing successful MH surgery. Pre- and post-operative en face OCT were manually segmented, and the correlation between parameters such as MH basal diameter and minimal inlet area, area of cyst in inner plexiform layer (IPL) and outer plexiform layer (OPL), percentage of cyst in IPL and OPL, and amount of ellipsoid zone (EZ) defect and external limiting membrane (ELM) defect was performed. Their relationship with visual acuity (VA) outcomes (Group 1: ≥20/60; 14 eyes; Group 2: <20/60; 14 eyes) was also evaluated.

Results

A significant positive correlation was noted between the cyst area in OPL and IPL (r=0.768; p<0.001), which in turn were positively correlated with the basal diameter of the MH in all eyes. The cyst area was significantly more in IPL as compared to OPL in all eyes (p=0.049) and in group 2 (p=0.03) but not in group 1 (p=0.62). As compared to group 2, eyes in group 1 had significantly better pre- and post-operative VA, and significantly smaller basal diameter, minimal inlet area, area of cyst in IPL and OPL, and amount of defect in the ELM (postoperative) and EZ (pre- and post-operative), respectively.

Conclusion

An increase in the basal diameter of the MH is associated with a simultaneous congruous enlargement of the area of cyst in IPL and OPL. Based on these imaging findings, we propose that the possible rationale for the origin of these intraretinal cysts could be a breakdown in the physiological retinal pigment epithelium (RPE) pump due to the anatomical separation of the neurosensory retina from the underlying RPE, ie, "RPE contact loss" theory.

Identification of epiretinal proliferation in various retinal diseases and vitreoretinal interface disorders

Background

To describe the presence of epiretinal proliferation in eyes with various retinal and vitreoretinal interface conditions.

Methods

Consecutive patients seen at the Stein Eye Institute, by one retina specialist, from December 2018 to March 2019, and demonstrating epiretinal proliferation on optical coherence tomography (OCT) were enrolled in this cross-sectional study. Included patients were divided into two groups: vitreoretinal interface pathologies group or retinal diseases group. Presence of epiretinal proliferation and its localization within the 9 macular sectors, as defined by the Early Treatment Diabetic Retinopathy Study (ETDRS), were assessed on OCT.

Results

77 eyes from 69 patients demonstrated epiretinal proliferation on OCT. The most frequently involved ETDRS sector was the 1-mm central subfield, followed by inner temporal and inner nasal sectors. Localization of epiretinal proliferation correlated with the presence of any retinal abnormalities in the same quadrant (r = 0.962; P < 0.0001). 31 eyes (40.3%) demonstrated symptomatic vitreoretinal interface pathologies including lamellar macular hole, full-thickness macular hole, epiretinal membrane and history of macular peeling. 46 eyes (59.7%) manifested various retinal diseases, including age-related macular degeneration, diabetic retinopathy, refractory macular edema, vein occlusion and high myopia.

Conclusions

Epiretinal proliferation was noted in several retinal conditions and not limited only to full-thickness and lamellar macular holes. Different mechanisms affecting retinal homeostasis might trigger Müller cells dysregulation, potentially leading to abnormal retinal remodeling.

Morphology of partial-thickness macular defects: presumed roles of Müller cells and tissue layer interfaces of low mechanical stability

BACKGROUND

The pathogenesis of partial-thickness macular defects and the role of Müller glial cells in the development of such defects are not well understood. We document the morphological characteristics of various types of partial-thickness macular defects using spectral-domain optical coherence tomography, with the focus on tractional and degenerative lamellar holes, and discuss possible pathogenic mechanisms.

METHODS

A retrospective case series of 61 eyes of 61 patients with different types of partial-thickness macular defects is described.

RESULTS

Partial-thickness macular defects are caused by anteroposterior or tangential traction onto the fovea exerted by the partially detached posterior hyaloid and epiretinal membranes, respectively. Tractional elevation of the inner Müller cell layer of the foveola-without (outer lamellar holes, foveal pseudocysts) or with a disruption of this layer (tractional lamellar holes, macular pseudoholes)-produces an elevation of the inner layers of the foveal walls (nerve fiber layer to outer plexiform layer [OPL]) and a schisis between the OPL and Henle fiber layer (HFL). With the exception of outer lamellar holes, the (outer part of the) central outer nuclear layer and the external limiting membrane remain nondisrupted in the various types of partial-thickness defects. Degenerative lamellar holes are characterized by cavitations between the inner plexiform layer and HFL of the foveal walls; many cases have lamellar hole-associated epiretinal proliferation (LHEP). Proliferating cells of the disrupted Müller cell cone may contribute to the development of LHEP and fill the spaces left by degenerated photoreceptors in the foveal center.

CONCLUSIONS

It is suggested that morphological characteristics of partial-thickness macular defects can be explained by the disruption of the (stalk of the) Müller cell cone in the foveola and the location of tissue layer interfaces with low mechanical stability: the boundary with no cellular connections between both Müller cell populations in the foveola, and the interface between the OPL and HFL in the foveal walls and parafovea. We propose that the development of the cavitations in degenerative lamellar holes is initiated by traction which produces a schisis between the OPL and HFL, and enlarged by a slow and chronic degeneration of Henle fibers and bipolar cells.Trial registration retrospectively registered, #143/20-ek, 04/03/2020.

Two different populations of Müller cells stabilize the structure of the fovea: an optical coherence tomography study

PURPOSE

To document with spectral-domain optical coherence tomography the structural stabilization of the fovea and the sealing of outer macular defects by Müller cells.

METHODS

A retrospective case series of 45 eyes of 34 patients is described.

RESULTS

In cases of a cystic disruption of the foveola as in macular telangiectasia type 2 and vitreomacular traction, the Müller cell cone provides the structural stability of the fovea. In cases of a detachment or disruption of the Müller cell cone, e.g., in foveal pseudocysts, outer lamellar holes, and degenerative and tractional lamellar holes, Müller cells of the foveal walls may provide the structural stability of the fovea by the formation of a hyperreflective external limiting membrane (ELM) which bridges the holes in the central outer nuclear layer (ONL). Müller cells of the foveal walls and parafovea mediate the regeneration of the foveal architecture in cases of outer lamellar and full-thickness macular holes. The regeneration proceeds by a centripetal displacement of photoreceptor cell somata which closes the holes in the central ONL. The closure may be supported by the formation of a glial tissue band at the ELM which seals the hole.

CONCLUSIONS

The Müller cell cone provides the foveal stability in cases of a cystic disruption of the foveola. The structural stability of the outer foveal layers is mainly provided by the Müller cells of the foveal walls and parafovea; these cells also mediate the regeneration of the outer fovea in cases of a defect of the central ONL.

Spontaneous closure of small full-thickness macular holes: Presumed role of Müller cells

PURPOSE

To document with spectral domain optical coherence tomography the formation and spontaneous closure of small full-thickness macular holes and to propose the active role of Müller cells in macular hole closure.

METHODS

A retrospective case series of five patients with spontaneous closure of macular holes is reviewed. In one patient, foveal images were recorded over a period of 18 months.

RESULTS

In a 66-year-old man, vitreofoveal traction caused a detachment of the inner Müller cell layer of the foveola from the outer nuclear layer (ONL) which was associated with a large pseudocyst and a horizontal gap in the central ONL. The traction caused an elongation and subsequent disruption of the stalk of the Müller cell cone in the foveola. A small full-thickness macular hole developed when a portion of the inner Müller cell layer of the foveola was pulled out. After phacoemulsification and shortly before the subsequent spontaneous closure of the hole, there were rapid increases in the number and size of the cystic cavities in the foveal walls resulting in a narrowing of the hole. The hole closed by bridging the gap in the inner part of the central ONL; a new inner Müller cell layer of the foveola was formed, and the gap of the external limiting membrane (ELM) was closed. The cystic cavities in the foveal walls rapidly disappeared within 2 weeks after the closure of the hole. One to 2.5 months after hole closure, the thickness of the central ONL increased which decreased the distance between the central ELM and retinal pigment epithelium. In three of the four other patients, the hole also closed by bridging the gap in the inner part of the ONL.

CONCLUSION

It is suggested that the spontaneous closure of small macular holes and the subsequent reconstruction of the normal foveal structure are mediated by active mechanisms of Müller cells which resemble those involved in ontogenetic foveal development.

Distinctive Mechanisms and Patterns of Exudative Versus Tractional Intraretinal Cystoid Spaces as Seen With Multimodal Imaging

PURPOSE

To determine clear-cut distinctions between tractional and exudative intraretinal cystoid spaces subtypes.

DESIGN

Retrospective, multicenter, observational case series.

METHODS

A cohort of patients diagnosed with intraretinal cystoid spaces and imaged with optical coherence tomography (OCT), fluorescein angiography (FA), blue fundus autofluorescence (BFAF), en face OCT, and OCT angiography (OCT-A) was included in the study. All images were qualitatively and quantitatively evaluated.

RESULTS

In this study were included 72 eyes of 69 patients. Exudative intraretinal cystoid spaces (36/72 eyes, 50%) displayed a "petaloid" morphology as seen with en face OCT, FA, and BFAF. Tractional intraretinal cystoid spaces (24/72 eyes, 33.3%), displayed a radial "spoke-wheel" en face OCT pattern. There was no leakage with FA and BFAF did not reveal specific patterns. Eyes with full-thickness macular hole (FTMH, 12/72 eyes, 16.7%) displayed a "sunflower" en face OCT appearance. FTMH showed OCT, OCT-A, and BFAF features of both exudative and tractional cystoid spaces, but without any FA leakage. Inner nuclear layer (INL) thickness was significantly lower in tractional cystoid spaces (P < .001). There were a greater number of INL cystoid spaces in both the exudative and FTMH subgroups (P = .001). The surface area of INL cystoid spaces was significantly lower in the tractional subgroup (P < .001). There was a significant reduction of the microvascular density in eyes with exudative vs tractional (P = .002) and FTMH (P < .001) subgroups.

CONCLUSIONS

Exudative and tractional intraretinal cystoid spaces displayed characteristic multimodal imaging features and they may represent 2 different pathologic conditions with equally different clinical implications.

Optical coherence tomography-based consensus definition for lamellar macular hole

BACKGROUND

A consensus on an optical coherence tomography definition of lamellar macular hole (LMH) and similar conditions is needed.

METHODS

The panel reviewed relevant peer-reviewed literature to reach an accord on LMH definition and to differentiate LMH from other similar conditions.

RESULTS

The panel reached a consensus on the definition of three clinical entities: LMH, epiretinal membrane (ERM) foveoschisis and macular pseudohole (MPH). LMH definition is based on three mandatory criteria and three optional anatomical features. The three mandatory criteria are the presence of irregular foveal contour, the presence of a foveal cavity with undermined edges and the apparent loss of foveal tissue. Optional anatomical features include the presence of epiretinal proliferation, the presence of a central foveal bump and the disruption of the ellipsoid zone. ERM foveoschisis definition is based on two mandatory criteria: the presence of ERM and the presence of schisis at the level of Henle's fibre layer. Three optional anatomical features can also be present: the presence of microcystoid spaces in the inner nuclear layer (INL), an increase of retinal thickness and the presence of retinal wrinkling. MPH definition is based on three mandatory criteria and two optional anatomical features. Mandatory criteria include the presence of a foveal sparing ERM, the presence of a steepened foveal profile and an increased central retinal thickness. Optional anatomical features are the presence of microcystoid spaces in the INL and a normal retinal thickness.

CONCLUSIONS

The use of the proposed definitions may provide uniform language for clinicians and future research.

Correlations between intraretinal cystoid cavities and pre- and postoperative characteristics of eyes after closure of idiopathic macular hole

Intraretinal cystoid cavities have been detected at the edges of macular holes (MHs) but their clinical characteristics and their relationship to the MH variables have not been determined. We measured the areas of the intraretinal cystoid cavity in 111 eyes with MHs in the OCT images preoperatively. Our results showed that the intraretinal cystoid cavities were located in the Henle fiber layer-outer nuclear layer (HFL-ONL) complex in 106 eyes and in the inner nuclear layer (INL) in 89 eyes. All were resolved after the initial vitrectomy to close the MH. The mean area of the cystoid cavity was greater in the HFL-ONL complex (55.9 ± 42.7 × 10³ μm²) than in the INL (9.1 ± 9.8 × 10³ μm²; P < 0.001). The area of the cystoid cavities was significantly correlated with the basal MH size (r = 0.465,P < 0.001), the external limiting membrane height (r = 0.793, P < 0.001), and the maximum retinal thickness (r = 0.757, P < 0.001). The area of the cystoid cavities was significantly correlated with the preoperative best-corrected visual acuity (BCVA; r = 0.361, P < 0.001), but not with the postoperative BCVA or the integrity of any of the outer retinal microstructural bands. The presence of intraretinal cystoid cavities was related to some morphological characteristics, but not to the postoperative BCVA or the restoration of the outer retinal bands.

Glia of the human retina

The human retina contains three types of glial cells: microglia and two types of macroglia, astrocytes and Müller cells. Macroglia provide homeostatic and metabolic support to photoreceptors and neurons required for neuronal activity. The fovea, the site of the sharpest vision which is astrocyte- and microglia-free, contains two populations of Müller glia: cells which form the Müller cell cone in the foveola and z-shaped Müller cells of the foveal walls. Both populations are characterized by morphological and functional differences. Müller cells of the foveola do not support the activity of photoreceptors and neurons, but provide the structural stability of the foveal tissue and improve the light transmission through the tissue to the photoreceptors. This article gives overviews of the glia of the human retina and the structure and function of both Müller cell types in the fovea, and describes the contributions of astrocytes and Müller cells to the ontogenetic development of the fovea.

Intraoperative OCT Findings May Predict Postoperative Visual Outcome in Eyes with Idiopathic Macular Hole

PURPOSE

To determine the significance of correlation between the intraoperative OCT findings and postoperative retinal morphologic and physiologic features in eyes with an idiopathic macular hole (MH).

DESIGN

Retrospective, interventional case-control study.

PARTICIPANTS

Pars plana vitrectomy with internal limiting membrane (ILM) peeling and air tamponade was performed on 33 eyes with idiopathic MHs. All of the eyes were followed up for at least 6 months.

METHODS

The intraoperative OCT (Rescan; Carl Zeiss Meditec, Oberkochen, Germany) images were used to detect the presence of residual fragments at the edge of the MH, and the eyes were divided into those with residual fragments (the residual group) and those without residual fragments (the nonresidual group).

MAIN OUTCOME MEASURES

The preoperative and postoperative OCT (Spectralis; Heidelberg Engineering, Heidelberg, Germany) findings and visual acuities were compared. The area of the hyperreflective tissue at the inner layer of the closed MH was measured with ImageJ software (National Institutes of Health, Bethesda, MD).

RESULTS

Residual fragments were detected in 22 eyes (67%), including 3 eyes with residual ILM fragments, and were not detected in 11 eyes. Age, gender, preoperative vision, refractive errors, and axial length were not significantly different between the 2 groups. The presence of residual fragments was associated significantly with the presence of epiretinal membrane (P = 0.040) and with epiretinal membrane, epiretinal proliferation, or both (P = 0.007) in the preoperative OCT images. However, they were not associated significantly with the presence of epiretinal proliferation and ILM fragments. The MHs were closed after surgery in all eyes with type 1 closure. Postoperative vision was significantly worse in the residual group at 3 and 6 months (P = 0.029 and P = 0.037, respectively). The sizes of the hyperreflective inner retinal tissue were significantly larger in the residual group than those in the nonresidual group at 1 and 3 months after surgery (P < 0.01). The sizes of the tissue decreased significantly after surgery in the residual group (P < 0.001) but not in the nonresidual group.

CONCLUSIONS

The residual fragments detected at the edge of the MH by intraoperative OCT may be the hyperreflective tissue observed in closed MHs and are predictors of limited postoperative visual improvements.

Idiopathic Macular Hole: A Comprehensive Review of Its Pathogenesis and of Advanced Studies on Metamorphopsia

Vitreous anteroposterior traction is an important factor that affects macular hole (MH) formation at the early stage, and vitreous tangential traction can lead to further hole expansion after hole formation. Recent studies have highlighted the significance of Müller cells for the pathogenesis of MH. Since the advent of MH treatment, success rates for MH closure have significantly improved, as has postoperative visual acuity. However, metamorphopsia, an initial and common symptom of MH, still exists. Metamorphopsia is significantly related to the deterioration of visual quality of life and can be used as an independent index to evaluate visual function before and after surgery. In MH patients, metamorphopsia has different manifestations representing different clinical implications. M-CHARTS, as a new means of inspection, can quantify the degrees of metamorphopsia, and with the development of optical coherence tomography (OCT), layer-by-layer scanning of the retinal structure has become possible. These methods enable detailed analysis of the connections between the degree of metamorphopsia and relevant OCT parameters. Preoperative OCT parameters can be used to evaluate the prognosis of the postoperative visual function of MH patients and are therefore of great significance in guiding the treatment of MH patients.

Optical coherence tomography angiography features in patients with idiopathic full-thickness macular hole, before and after surgical treatment

Purpose

To present optical coherence tomography (OCT) angiography features in patients with idiopathic full-thickness macular hole before and after vitrectomy.

Study design

Prospective case series study.

Materials and methods

Patients presenting with an idiopathic full-thickness macular hole (IMH) who underwent posterior vitrectomy with internal limiting membrane peeling and gas tamponade were included in the study. En face OCT and OCT angiography (OCTA) was performed pre- and postoperatively using 3×3 mm scans (Optovue, XR Avanti). Foveal avascular zone (FAZ) area, macular hole size (MHS), central retinal thickness (CRT), macular parafoveal choriocapillary flow area (MCFA), and fovea vessel density (FVDS) were measured and assessed using OCTA. Best-corrected visual acuity (BCVA) was examined before and 3 months after surgery.

Results

Twenty-eight eyes of 28 patients were included in the study. The mean age of patient group was 68.28 years. The hole was closed in all eyes after the initial surgery. OCTA showed enlargement of FAZ and increased CRT in foveal area. Mean preoperative FAZ area was 0.39±0.07 mm². En face images of the middle retina showed a range of preoperative cystic patterns surrounding the hole. BCVA was improved from 0.1±0.11 preoperatively to 0.42±0.17 postoperatively. Mean FAZ area was reduced to 0.24±0.07 mm² postoperatively with resolution of macular hole and adjacent cystic areas. Mean CRT was reduced from 396±62.6 µm pre-operatively to 272±30.7 µm postoperatively. After vitrectomy, the parafoveal choriocapillary flow area and FVDS of IMH eyes increased compared with the preoperative measurements.

Conclusion

Quantitative evaluation of vascular and morphological changes following IMH surgery using OCTA shows the potential for recovery due to vascular and neuronal plasticity. OCTA showing vascular changes and their quantitative characteristics might be a useful tool for the assessment of macular holes before and after surgical treatment.

Antecedents of Soft Drusen, the Specific Deposits of Age-Related Macular Degeneration, in the Biology of Human Macula

AMD pathobiology was irreversibly changed by the recent discovery of extracellular cholesterol-containing deposits in the subretinal space, between the photoreceptors and retinal pigment epithelium (RPE), called subretinal drusenoid deposits (SDDs). SDDs strikingly mirror the topography of rod photoreceptors in human macula, raising the question of whether an equivalent process results in a deposition related to foveal cones. Herein we propose that AMD's pathognomonic lesion-soft drusen and basal linear deposit (BLinD, same material, diffusely distributed)-is the leading candidate. Epidemiologic, clinical, and histologic data suggest that these deposits are most abundant in the central macula, under the fovea. Strong evidence presented in a companion article supports the idea that the dominant ultrastructural component is large apolipoprotein B,E-containing lipoproteins, constitutively secreted by RPE. Lipoprotein fatty acids are dominated by linoleate (implicating diet) rather than docosahexaenoate (implicating photoreceptors); we seek within the retina cellular relationships and dietary drivers to explain soft druse topography. The delivery of xanthophyll pigments to highly evolved and numerous Müller cells in the human fovea, through RPE, is one strong candidate, because Müller cells are the main reservoir of these pigments, which replenish from diet. We propose that the evolution of neuroglial relations and xanthophyll delivery that underlie exquisite human foveal vision came with a price, that is, soft drusen and sequela, long after our reproductive years.

Swept source optical coherence tomography and optical coherence tomography angiography in pediatric enhanced S-cone syndrome: a case report

Background

Enhanced S-cone syndrome is an autosomal recessive retinal dystrophy related to a defect in a nuclear receptor gene (NR2E3) that leads to alteration in cells development from rod to S-cone. This retinal dystrophy may be associated with retinal schisis. The aim of this report is to describe structural optical coherence tomography and optical coherence tomography angiography features in a case of enhanced S-cone syndrome associated with macular schisis.

Case presentation

A Caucasian 13-year-old girl underwent measurement of best corrected visual acuity, ophthalmoscopic evaluation, and fundus autofluorescence examination. Photopic and scotopic electroretinography were carried out as well. Enhanced S-cone syndrome was suspected on the basis of clinical and electrophysiological findings. Structural optical coherence tomography and optical coherence tomography angiography allowed the further characterization of the associated macular schisis.

Genetic analysis not only confirmed the diagnosis but increased the clinical novelty of this case report by showing two variations in the NR2E3 gene probably related to the phenotype: a missense variation c.1118T>C which leads to the substitution of leucine with proline in amino acid position 373, and c.349+5G>C, which involves a gene sequence near a splicing site.

Conclusions

Swept source structural optical coherence tomography (B scans and “en face” images) and optical coherence tomography angiography allowed the observation of retinal structural details and the involvement of each retinal layer and capillary plexus in enhanced S-cone syndrome. Of interest, neither of the two NR2E3 gene variants found in this case report have been linked to any form of retinopathy.

Rod-Mediated Dark Adaptation and Macular Pigment Optical Density in Older Adults with Normal Maculas

PURPOSE

To examine the association between macular pigment optical density (MPOD) and rod-mediated dark adaptation (RMDA) in persons ≥60 years old with normal maculas as determined by an accepted color fundus photography grading system.

METHODS

This cross-sectional analysis used baseline data from eyes in the Alabama Study on Early Age-Related Macular Degeneration. Eyes at step 1 in the AREDS 9-step grading system were considered normal. Eyes were additionally assessed by spectral domain optical coherence tomography (SD-OCT). Foveal MPOD was estimated via heterochromatic flicker photometry, and RMDA was assessed with a computerized dark adaptometer. The association between RMDA and MPOD was examined via Spearman correlation coefficients adjusted for age.

RESULTS

In 306 eyes from 306 persons (mean age 68.2 years) in normal macular health, MPOD was not associated with RMDA (age-adjusted rank correlation = 0.043, p = 0.45). After 81 eyes with incidental macular findings by SD-OCT evaluation were excluded, the association between MPOD and RMDA remained null (N = 225, age-adjusted r = 0.015, p = 0.82).

CONCLUSION

In a large sample of normal aged eyes, RMDA, a visual function that is rate limited by retinoid availability to photoreceptors across the complex of retinal pigment epithelium, Bruch's membrane, and choriocapillaris, is not related to MPOD in the neurosensory retina.

The primate fovea: Structure, function and development

A fovea is a pitted invagination in the inner retinal tissue (fovea interna) that overlies an area of photoreceptors specialized for high acuity vision (fovea externa). Although the shape of the vertebrate fovea varies considerably among the species, there are two basic types. The retina of many predatory fish, reptilians, and birds possess one (or two) convexiclivate fovea(s), while the retina of higher primates contains a concaviclivate fovea. By refraction of the incoming light, the convexiclivate fovea may function as image enlarger, focus indicator, and movement detector. By centrifugal displacement of the inner retinal layers, which increases the transparency of the central foveal tissue (the foveola), the primate fovea interna improves the quality of the image received by the central photoreceptors. In this review, we summarize ‒ with the focus on Müller cells of the human and macaque fovea ‒ data regarding the structure of the primate fovea, discuss various aspects of the optical function of the fovea, and propose a model of foveal development. The "Müller cell cone" of the foveola comprises specialized Müller cells which do not support neuronal activity but may serve optical and structural functions. In addition to the "Müller cell cone", structural stabilization of the foveal morphology may be provided by the 'z-shaped' Müller cells of the fovea walls, via exerting tractional forces onto Henle fibers. The spatial distribution of glial fibrillary acidic protein may suggest that the foveola and the Henle fiber layer are subjects to mechanical stress. During development, the foveal pit is proposed to be formed by a vertical contraction of the centralmost Müller cells. After widening of the foveal pit likely mediated by retracting astrocytes, Henle fibers are formed by horizontal contraction of Müller cell processes in the outer plexiform layer and the centripetal displacement of photoreceptors. A better understanding of the molecular, cellular, and mechanical factors involved in the developmental morphogenesis and the structural stabilization of the fovea may help to explain the (patho-) genesis of foveal hypoplasia and macular holes.

Measurement of full-thickness macular hole size using en face optical coherence tomography

PurposeTo assess the feasibility and interest of measuring macular hole (MH) size using en face optical coherence tomography (OCT) compared with manual diameter measurements on B-scans.MethodsAmong our previously published series of 100 patients operated for primary MH, patients whose images were acquired with Cirrus 5000 HD-OCT (Carl Zeiss Meditec) with a quality signal strength >5/10 were included. Three segmentations (internal limiting membrane, horizontal, and retinal pigment epithelium (RPE)) were compared for obtaining the most appropriate en face image. MH surface areas were measured using ImageJ software. Mean diameters calculated from surface areas (diameter=2 × √(surface area/π)) were compared with those measured on B-scans.ResultsNineteen patients were included with a mean age of 72±8 years (56-86) and a female predominance (3/16). The mean absolute difference between horizontal and vertical diameters measured on B-scans was of 54±47 μm (0-180) without reaching significance (P=0.874). RPE segmentation provided the best en face image and was feasible without and with adjustment, respectively, in 79% and 100% (cases with vitreomacular traction) of cases. No significant difference in mean diameters was observed between those calculated from en face images (435±143 μm (195-693)) and those measured on horizontal B-scans (426±139 μm (214-705), P=0.482).ConclusionMeasuring MH size on en face OCT images is feasible, reliable, and eliminates the potential bias related to manual measurements on B-scans. Its integration into OCT devices would offer an automated and easy-to-use option for clinical practice.

Tractional Abnormalities of the Central Foveal Bouquet in Epiretinal Membranes: Clinical Spectrum and Pathophysiological Perspectives

PURPOSE

To investigate the tractional alterations of the central bouquet (CB) in idiopathic epiretinal membranes (ERMs).

DESIGN

Retrospective, consecutive, observational case series.

METHODS

ERMs were classified according to a 4-stage grading system. The CB was defined as a circular area of approximately 100 μm composed of densely packed cones (and Müller cells) in the central fovea. Tractional abnormalities of the CB were identified with spectral-domain optical coherence tomography. Ex vivo histopathologic analysis was performed.

RESULTS

In this study 263 eyes with ERMs were included. Mean follow-up was 21.2 ± 16.7 months. At baseline, tractional abnormalities of the CB were diagnosed in 58 out of 263 eyes (22%) and divided into 3 categories: cotton ball sign (defined as a fuzzy hyperreflective area between the ellipsoid zone and the interdigitation zone in the central fovea), foveolar detachment, and acquired vitelliform lesion. The presence of ectopic inner foveal layers was negatively correlated with the presence of CB tractional abnormalities (P = .002). Visual acuity was highest in association with the cotton ball sign and lowest in the acquired vitelliform lesion group. Sequential morphologic progression was identified in 7 eyes. Ex vivo histopathologic analysis illustrated characteristic staining patterns supporting a potential mechanism of traction by Müller cells in the CB.

CONCLUSIONS

The cotton ball sign, foveolar detachment, and acquired vitelliform lesion may comprise a continuum in the same clinical spectrum and may represent subsequent stages of CB abnormalities. Foveal Müller cells may play an integral role in the transmission of mechanical forces to the central foveal cones.

Potential role of Müller cells in the pathogenesis of macropsia associated with epiretinal membrane: a hypothesis revisited

Pathophysiological explanations for metamorphopsia associated with retinal pathologies generally focus on photoreceptor organization disruption. However, the retinal microarchitecture is complicated, and we hypothesize that other retinal cells may also be involved. Metamorphopsia has been widely studied in eyes with epiretinal membranes and we revisit the idea that Müller cell displacement causes retinal macropsia. A PubMed query and related article search for the macula ultrastructure under normal and pathological conditions revealed an enormous amount of information, particularly ultrahigh definition optical coherence tomography and other retinal imaging modality studies. Findings of these imaging studies support our hypothesis that Müller cells, and not cone photoreceptors, are primarily responsible for macropsia in eyes with epiretinal membranes. More specifically, we conclude that displacement of Müller cell endfeet, and not photoreceptor cones, is a more likely the explanation for retinal macropsia associated with epiretinal membranes.

Mechanisms of macular edema: Beyond the surface

Macular edema consists of intra- or subretinal fluid accumulation in the macular region. It occurs during the course of numerous retinal disorders and can cause severe impairment of central vision. Major causes of macular edema include diabetes, branch and central retinal vein occlusion, choroidal neovascularization, posterior uveitis, postoperative inflammation and central serous chorioretinopathy. The healthy retina is maintained in a relatively dehydrated, transparent state compatible with optimal light transmission by multiple active and passive systems. Fluid accumulation results from an imbalance between processes governing fluid entry and exit, and is driven by Starling equation when inner or outer blood-retinal barriers are disrupted. The multiple and intricate mechanisms involved in retinal hydro-ionic homeostasis, their molecular and cellular basis, and how their deregulation lead to retinal edema, are addressed in this review. Analyzing the distribution of junction proteins and water channels in the human macula, several hypotheses are raised to explain why edema forms specifically in the macular region. "Pure" clinical phenotypes of macular edema, that result presumably from a single causative mechanism, are detailed. Finally, diabetic macular edema is investigated, as a complex multifactorial pathogenic example. This comprehensive review on the current understanding of macular edema and its mechanisms opens perspectives to identify new preventive and therapeutic strategies for this sight-threatening condition.

Vascular Features of Full-Thickness Macular Hole by OCT Angiography

BACKGROUND AND OBJECTIVE

To compare the features of cystoid cavities associated with full-thickness macular hole (FTMH) imaged with optical coherence tomography angiography (OCTA) and en face OCT.

PATIENTS AND METHODS

Prospective, observational, cross-sectional study. Clinical practice and observation. Thirteen patients (13 eyes) with FTMH were evaluated before vitrectomy. All eyes underwent OCTA or en face OCT imaging.

RESULTS

There was a statistically significant positive correlation between groups for the total cavity area in both inner nuclear layer (P < .001; r² = 0.82) and outer plexiform and Henle fiber layer complex (P < .001; r² = 0.84).

CONCLUSIONS

OCTA and en face image of cystoid cavities show very similar features and are complementary for the evaluation of the disease. The OCTA images show "vascular sliding" at the border of the cystoid cavities in FTMH, suggesting preservation of microvasculature surrounding the cystoid spaces during the disease process. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:62-68.].

Preoperative and postoperative features of macular holes on en face imaging and optical coherence tomography angiography

Purpose

To characterize and quantify the pre- and postoperative foveal structural and functional patterns in full-thickness macular holes.

Methods

Subjects presenting with a full-thickness macular hole that had pre- and postoperative imaging were included. En face optical coherence tomography (OCT) and OCT angiography (OCTA) was performed. Foveal avascular zone (FAZ) area, macular hole size, number and size of perifoveal cysts were measured.

Results

Five eyes from 5 patients were included in the study. The hole was closed in all eyes after the initial surgery. OCTA showed enlargement of the FAZ and delineation of the holes within the FAZ. Mean preoperative FAZ area was 0.41 ± 0.104 mm². Visual acuity was improved and mean FAZ area was reduced to 0.27 ± 0.098 mm² postoperatively (P < 0.05) with resolution of the macular hole and adjacent cystic areas. En face images of the middle retina showed a range of preoperative cystic patterns surrounding the hole. Smaller holes showed fewer but larger cystic areas and larger holes had more numerous but smaller cystic areas.

Conclusions and importance

Quantitative evaluation of vascular and cystic changes following macular hole repair demonstrates the potential for recovery due to neuronal and vascular plasticity. Perifoveal microstructural patterns and their quantitative characteristics may serve as useful anatomic biomarkers for assessment of macular holes.