Foveal fine structure in retinopathy of prematurity: an adaptive optics Fourier domain optical coherence tomography study

The Mongolian gerbil as an advanced model to study cone system physiology

In this work, we introduce a diurnal rodent, the Mongolian gerbil (Meriones unguiculatus) (MG) as an alternative to study retinal cone system physiology and pathophysiology in mice. The cone system is of particular importance, as it provides high-acuity and color vision and its impairment in retinal disorders is thus especially disabling. Despite their nocturnal lifestyle, mice are currently the most popular animals to study cone-related diseases due to the high availability of genetically modified models. However, the potential for successful translation of any cone-related results is limited due to the substantial differences in retinal organization between mice and humans. Alternatively, there are diurnal rodents such as the MG with a higher retinal proportion of cones and a macula-like specialized region for improved visual resolution, the visual streak. The focus of this work was the evaluation of the MG's cone system functionality using full-field electroretinography (ERG), together with a morphological assessment of its retinal/visual streak organization via angiography, optical coherence tomography (OCT), and photoreceptor immunohistochemistry. We found that rod system responses in MGs were comparable or slightly inferior to mice, while in contrast, cone system responses were much larger, more sensitive, and also faster than those in the murine counterparts, and in addition, it was possible to record sizeable ON and OFF ERG components. Morphologically, MG cone photoreceptor opsins were evenly distributed throughout the retina, while mice show a dorsoventral M- and S-opsin gradient. Additionally, each cone expressed a single opsin, in contrast to the typical co-expression of opsins in mice. Particular attention was given to the visual streak region, featuring a higher density of cones, elongated cone and rod outer segments (OSs), and an increased thickness of the inner and outer retinal layers in comparison to peripheral regions. In summary, our data render the MG a supreme model to investigate cone system physiology, pathophysiology, and to validate potential therapeutic strategies in that context.

Potential application of foveal structural measurements in treatment decision for retinopathy of prematurity: an OCT-based study

PURPOSE

To investigate foveal changes in infants with ROP not requiring treatment(nROP) and ROP infants needing treatment (tROP) using a handheld SD-OCT device.

METHOD

We performed horizontal SD-OCT scans through the fovea in 156 eyes of 81 infants diagnosed with ROP. Foveal immaturity indices including the presence of inner retinal layers (IRL), absence of foveal outer nuclear layers widening (ONL) and attenuation of hyperreflective outer segment layers (OS), presence and type of cystoid macular edema (CME), epiretinal membrane (ERM), foveal pit depth (FPD), foveal pit width (FPW) and central foveal thickness (CFT) were calculated. The multivariate logistic regression model was used to predict the need for treatment based on OCT measurements.

RESULTS

The shape of the foveolar pit was not significantly different among tROP and nROP groups (P-value = 0.287, Chi-square test). IRL extrusion was incomplete in both tROP and nROP groups (P-value = 0.0.41, Chi-square test). Nevertheless, the presence of thicker IRL was more frequent in the nROP group in comparison with the tROP group (100% vs.64.8%, P-value = 0.001). CME was observed in 29% of eyes in the tROP group and 40% of eyes in the nROP group; however, this difference was not statistically significant (P-value = 0.32, Chi-square test). ERM was detected in 15 (75%) and 84 (65.6%) eyes in the nROP and tROP groups, respectively (P-value = 0.39, Chi-square test). Multivariate logistic regression analyses showed that the need for treatment was significantly associated with gestational age (GA), CFT and FPD (P-values 0.001 and 0.002 respectively).

CONCLUSIONS

This study demonstrated GA, foveal pit depth and the central foveal thickness could accurately predict the need for treatment with sensitivity, specificity, and diagnostic accuracy of 97%, 65% and 91.7% respectively.

Twenty-five years of clinical applications using adaptive optics ophthalmoscopy [Invited]

Twenty-five years ago, adaptive optics (AO) was combined with fundus photography, thereby initiating a new era in the field of ophthalmic imaging. Since that time, clinical applications of AO ophthalmoscopy to investigate visual system structure and function in both health and disease abound. To date, AO ophthalmoscopy has enabled visualization of most cell types in the retina, offered insight into retinal and systemic disease pathogenesis, and been integrated into clinical trials. This article reviews clinical applications of AO ophthalmoscopy and addresses remaining challenges for AO ophthalmoscopy to become fully integrated into standard ophthalmic care.

Macular thickness variation and interocular symmetry by gestational age in preterm school-age children

PURPOSE

To determine changes in macular thickness profile according to gestational age (GA) and to assess interocular symmetry in the macula of children born very preterm.

METHODS

In this cross-sectional study of preterm (n = 106) and term-born (n = 49) children 5-8 years of age at time of examination, optical coherence tomography was used to measure macula thickness as described in the ETDRS study. Statistical analyses included stratified and multivariable analyses.

RESULTS

Foveal minimum thickness increased with decreasing GA (P for trend, <0.001; 254.7 ± 32.8 μm for children born at 24-25 weeks and 193.2 ± 32.8 μm in term-born children). Inner and outer area thickness differed for term and preterm children, but did not vary with the degree of prematurity (inner area, 267.0 ± 11.0 μm for 24-25 weeks' GA and 305.4 ± 11.8 μm for term children [P < 0.01]; outer ring, 305.5 ± 10.4 μm in extreme preterm and 271.0 ± 10.4 μm in term children [P < 0.01]). Interocular asymmetry in preterm children was not significant for most areas; the largest interocular difference was found in the central zone (16.3 ±16.6 μm).

CONCLUSIONS

In our study cohort, children born very preterm examined at school age compared to term born children had greater central thickness with decreased foveal pit, decreased inner ring, and increased thickness of the outer ring. They did not show greater interocular asymmetry.

Structural impact of arrested foveal development in children born extremely preterm without ROP at 6.5 years of age

Objectives

To characterize changes of foveal topography and microstructure of persisting foveal immaturity at 6.5 years of age in children born extremely preterm without retinopathy of prematurity (EPT-NoROP).

Methods

Images from previous optical coherence tomography examinations of 37 EPT-NoROP and 92 control eyes were selected from a regional cohort of the EXPRESS (Extremely Preterm Infants in Sweden) study. Thickness of ganglion cell + inner plexiform layer (GCL+), outer nuclear layer (ONL), retinal thickness (RT) at the foveal centre (FC), foveal depth (FD) and RT at the foveal rim were evaluated.

Results

Layer thickness of GCL+, ONL and RT was increased at FC in the EPT-NoROP group. More than two-thirds had thickness values above the control limit (control mean +2 SD) at FC (GCL + 68%, ONL 76%, and RT 68%), and 50% had reduced FD compared to controls. All parameters showed a high correlation within the EPT-NoROP group, whereas no or weaker correlation was seen in control eyes. The EPT-NoROP sub-groups, divided based on the control limit, did not differ in terms of associated factors such as gestational age, birth weight, visual acuity, and refraction.

Conclusions

Extreme prematurity without impact of ROP is associated with increased GCL + , ONL, and RT thickness at FC as well as reduced FD compared to full-term controls at age 6.5. This indicates that prematurity per se may have a profound effect on foveal anatomical maturation during the first months after birth. Our results suggest RT at FC to be a simple and useful measure of foveal anatomical immaturity.

Insights into the developing fovea revealed by imaging

Early development of the fovea has been documented by histological studies over the past few decades. However, structural distortion due to sample processing and the paucity of high-quality post-mortem tissue has limited the effectiveness of this approach. With the continuous progress in high-resolution non-invasive imaging technology, most notably optical coherence tomography (OCT) and OCT angiography (OCT-A), in vivo visualization of the developing retina has become possible. Combining the information from histologic studies with this novel imaging information has provided a more complete and accurate picture of retinal development, and in particular the developing fovea. Advances in neonatal care have increased the survival rate of extremely premature infants. However, with enhanced survival there has been an attendant increase in retinal developmental complications. Several key abnormalities, including a thickening of the inner retina at the foveal center, a shallower foveal pit, a smaller foveal avascular zone, and delayed development of the photoreceptors have been described in preterm infants when compared to full-term infants. Notably these abnormalities, which are consistent with a partial arrest of foveal development, appear to persist into later childhood and adulthood in these eyes of individuals born prematurely. Understanding normal foveal development is vital to interpreting these pathologic findings associated with prematurity. In this review, we first discuss the various advanced imaging technologies that have been adapted for imaging the infant eye. We then review the key events and steps in the development of the normal structure of the fovea and contrast structural features in normal and preterm retina from infancy to childhood. Finally, we discuss the development of the perifoveal retinal microvasculature and highlight future opportunities to expand our understanding of the developing fovea.

RETINAL THICKNESS AND FOVEAL HYPOPLASIA IN ADULTS BORN PRETERM WITH AND WITHOUT RETINOPATHY OF PREMATURITY: The Gutenberg Prematurity Eye Study

PURPOSE

This study analyses whether prematurity, retinopathy of prematurity (ROP), and associated factors lead to altered foveal shape in adulthood and whether these alterations are associated with visual acuity.

METHODS

The Gutenberg Prematurity Eye Study is a German cohort study with a prospective ophthalmologic examination (participants aged 18-52 years) of individuals born preterm and full-term that were examined with spectral domain optical coherence tomography. Participants were grouped according to gestational age (GA) and postnatal ROP status. Multivariable linear regression analyses for foveolar retinal thickness, foveal hypoplasia, and posterior vitreous status were performed.

RESULTS

A total of 755 eyes of 414 preterm and full-term individuals were included (aged 28.6 ± 8.6 years, 233 female individuals). Central foveal retinal thickness increased as GA decreased. The prevalence of foveal hypoplasia was 2% (control group), 9% (GA 33-36), 18% (GA 29-32), 48% (GA ≤28), 50% (ROP without treatment), and 82% of eyes (with ROP requiring treatment). In multivariable analyses, central foveal thickness was independently associated with GA and advanced stages of ROP requiring treatment while foveal hypoplasia was only associated with GA. Posterior vitreous was more frequently visible as partially detached in full-term than in preterm individuals. Lower distant-corrected visual acuity correlated with increased foveolar thickness (rho = 0.08; P = 0.03) and with foveal hypoplasia (rho = 0.15, P < 0.001).

CONCLUSION

Our findings indicate that there are fetal origins affecting foveal shape, resulting in foveal hypoplasia potentially affecting the visual acuity in adulthood.

Neurosensory Alterations in Retinopathy of Prematurity: A Window to Neurological Impairments Associated to Preterm Birth

Retinopathy of prematurity (ROP) is one of the main blinding diseases affecting preterm newborns and is classically considered a vascular disorder. The premature exposure to the extrauterine environment, which is hyperoxic in respect to the intrauterine environment, triggers a cascade of events leading to retinal ischemia which, in turn, makes the retina hypoxic thus setting off angiogenic processes. However, many children with a history of ROP show persistent vision impairment, and there is evidence of an association between ROP and neurosensory disabilities. This is not surprising given the strict relationship between neuronal function and an adequate blood supply. In the present work, we revised literature data evidencing to what extent ROP can be considered a neurodegenerative disease, also taking advantage from data obtained in preclinical models of ROP. The involvement of different retinal cell populations in triggering the neuronal damage in ROP was described along with the neurological outcomes associated to ROP. The situation of ROP in Italy was assessed as well.

Normal and abnormal foveal development

Normal foveal development begins in utero at midgestation with centrifugal displacement of inner retinal layers (IRLs) from the location of the incipient fovea. The outer retinal changes such as increase in cone cell bodies, cone elongation and packing mainly occur after birth and continue until 13 years of age. The maturity of the fovea can be assessed invivo using optical coherence tomography, which in normal development would show a well-developed foveal pit, extrusion of IRLs, thickened outer nuclear layer and long outer segments. Developmental abnormalities of various degrees can result in foveal hypoplasia (FH). This is a characteristic feature for example in albinism, aniridia, prematurity, foveal hypoplasia with optic nerve decussation defects with or without anterior segment dysgenesis without albinism (FHONDA) and optic nerve hypoplasia. In achromatopsia, there is disruption of the outer retinal layers with atypical FH. Similarly, in retinal dystrophies, there is abnormal lamination of the IRLs sometimes with persistent IRLs. Morphology of FH provides clues to diagnoses, and grading correlates to visual acuity. The outer segment thickness is a surrogate marker for cone density and in foveal hypoplasia this correlates strongly with visual acuity. In preverbal children grading FH can help predict future visual acuity.

Comparison of OCT imaging in children with foveal hypoplasia born full term versus preterm

PURPOSE

It is unknown if foveal hypoplasia in full-term born children differs in structure and function from that observed in children born preterm. We compared macular structure and visual function in children with history of prematurity and full-term children diagnosed with foveal hypoplasia.

METHODS

We compared three groups of subjects (3-18 years old): (1) full-term hypoplasia (FH, n = 56, gestational age ≥ 36 weeks); (2) preterm hypoplasia (n = 57, gestational age ≤ 31 weeks, birth weight ≤ 1500 g); (3) control (n = 54), full-term normal. Using spectral-domain optical coherence tomography volume-scan images, macular structure within 3 mm of Early-Treatment-Diabetic-Retinopathy-Study circle was segmented. Total, inner, and outer foveal thickness of right eyes were compared. Foveal hypoplasia was graded according to the Leicester Grading System.

RESULTS

The mean total foveal thickness in micrometers was 263 ± 19 for the control, 299 ± 30 for the full-term hypoplasia, and 294 ± 28 for the preterm hypoplasia groups (F = 33, p < 0.001). Foveal inner retinal layer thickness differed among groups (p < 0.001), but not in the outer layers (p = 0.10). The full-term hypoplasia group had significantly thicker foveal inner layers (p < 0.05) and greater frequency of higher-grade hypoplasia than the preterm hypoplasia group. LogMAR visual acuity was worse in the full-term hypoplasia group (0.35 ± 0.36) than in the preterm hypoplasia group (0.19 ± 0.27, p < 0.001).

CONCLUSION

Fovea was thicker in both hypoplasia groups. The full-term hypoplasia group is associated with more severe structure changes and poorer visual function than the preterm hypoplasia group.

Foveal structure changes in infants treated with anti-VEGF therapy or laser therapy guided by optical coherence tomography angiography for retinopathy of prematurity

AIM

To evaluate foveal vessel density (VD) and foveal thickness using optical coherence tomography angiography (OCTA) in retinopathy of prematurity (ROP) children treated with laser photocoagulation or anti-vascular endothelial growth factor (VEGF) injection. Additionally, we assessed the relationship between foveal microvascular anomalies and different therapies in ROP children.

METHODS

This was a single-center, retrospective study of patients with a diagnosis of type 1 ROP. Twenty-three eyes (14 patients) treated with anti-VEGF injection and twenty-nine eyes (17 patients) treated with laser coagulation were included in this study. The foveal VD, inner thickness and full thickness were measured at the central 0°, 2° to 8°, and 8° of the retina (centered on the fovea) using OCTA and cross-sectional OCT, respectively.

RESULTS

Foveal VD, inner thickness and full thickness were significantly smaller within the central 8° of the retina in ROP children treated with anti-VEGF injection than in those treated with laser photocoagulation (P=0.013, 0.009, 0.036, respectively). The full thickness was also smaller in the anti-VEGF group than in the laser group at the central 0° of the retina (P=0.010). The grade of foveal hypoplasia is lower in the anti-VEGF group than in the laser group (P=0.045). Multivariable analysis did not find any risk factors associated with visual acuity in our study.

CONCLUSION

In children with type 1 ROP, the better structural development of fovea in those who were treated with anti-VEGF injection compared with laser photocoagulation are identified. However, visual acuity outcomes are similar 70mo after the treatments.

Association of Birth Weight With Foveolar Thickness in Adulthood: Results From a Population-Based Study

Purpose

Low birth weight (BW) is associated with alterations of foveal shape development in childhood-leading to an increased retinal thickness of the fovea. The aim of the present study was to assess whether BW has a long-term effect on foveal retinal thickness (RT) and is still present in adulthood.

Methods

In the German population-based Gutenberg Health Study (GHS), participants were examined with spectral-domain optical coherence tomography. The association between self-reported BW and RT in the foveolar and perifoveal locations was assessed. Multivariable linear regression analyses with adjustment for potential confounders and grading of foveal hypoplasia were performed.

Results

Overall, RT measurements and self-reported BW were available for 2,539 participants (1300 female, mean age 54.5 ± 9.7 years). The absolute foveolar RT was 239.6 ± 25.8 µm, 232.2 ± 20.1 µm and 234.8 ± 21.0 µm, respectively, in the low (<2500 g), normal (2500-4000 g) and high (>4000 g) BW groups (P < 0.001). After adjustment for confounders, an association was observed between lower BW and increased foveolar thickness (B = -0.35 [95% confidence interval {CI}: -0.49; -0.20] µm/100 g; P < 0.001), whereas only a weak association with RT was observed with the nasal (P = 0.010), temporal (P = 0.011), and inferior (P = 0.021) quadrants in the 1 mm distance, with no association in the 2 mm distance to the fovea. Foveal hypoplasia grade 1 was more frequent in the low BW group (6.8%) compared to the normal (0.9%) and high BW group (1.2%).

Conclusions

This study provides evidence of an association between lower BW and increased foveolar thickness and foveal hypoplasia, indicating that prenatal growth may affect macular morphology, which in turn may persist until adulthood and predispose to retinal disease later in life.

MORPHOFUNCTIONAL EVALUATION OF MACULAR-FOVEAL CAPILLARIES: A Comparative Optical Coherence Tomography Angiography and Microperimetry Study

PURPOSE

To analyze the macular function of eyes with macular-foveal capillaries (MFC), a condition characterized by the absence of the foveal avascular zone (FAZ), identified by optical coherence tomography angiography.

METHODS

Eight eyes with MFC at optical coherence tomography angiography and normal visual acuity were consecutively recruited. Eight eyes of healthy subjects were enrolled as healthy controls. All eyes underwent optical coherence tomography, optical coherence tomography angiography, best-correct visual acuity, low-luminance visual acuity, contrast sensitivity measurement, colour vision tests, and both mesopic and scotopic microperimetry.

RESULTS

Best-corrected visual acuity, low-luminance visual acuity, contrast sensitivity, and colour vision tests did not differ between the two groups. At mesopic microperimetry, both foveal retinal sensitivity and mean mesopic retinal sensitivity of the central 1° were statistically inferior in MFC versus control eyes (P < 0.0001 and P < 0.0001, respectively). At scotopic microperimetry, a dense foveal scotoma, normally present in control eyes, was completely lacking in MFC eyes. Scotopic foveal retinal sensitivity was statistically superior in MFC versus control eyes (P = 0.009).

CONCLUSION

The absence of the foveal dense scotoma in scotopic conditions underlines that the foveal rod-free zone is not present when capillaries are present in this area. An anomalous foveal distribution of photoreceptors, with both rods and cones present in this area, may be postulated in MFC eyes.

Adaptive optics ophthalmoscopy: a systematic review of vascular biomarkers

Retinal vascular diseases are a leading cause for blindness and partial sight certifications. By applying adaptive optics (AO) to conventional imaging modalities, the microstructures of the retinal vasculature can be observed with high spatial resolution, hence offering a unique opportunity for the exploration of the human microcirculation. The objective of this systematic review is to describe the current state of retinal vascular biomarkers imaged by AO flood illumination ophthalmoscopy (FIO) and AO scanning laser ophthalmoscopy (SLO). A literature research was conducted in the PubMed and Scopus databases on July 9, 2020. From 217 screened studies, 42 were eligible for this review. All studies underwent a quality check regarding their content. A meta-analysis was performed for the biomarkers reported for the same pathology in at least three studies using the same modality. The most frequently studied vascular biomarkers were the inner diameter (ID), outer diameter (OD), parietal thickness (PT), wall cross-sectional area (WCSA), and wall-to-lumen ratio (WLR). The applicability of AO vascular biomarkers has been mostly explored in systemic hypertension using AO FIO and in diabetes using AO SLO. The result of the meta-analysis for hypertensive patients showed that WLR, PT, and ID were significantly different when compared to healthy controls, while WCSA was not (P < 0.001, P = 0.002, P < 0.001, and P = 0.070, respectively). The presented review shows that, although a substantial number of retinal vascular biomarkers have been explored in AO en face imaging, further clinical research and standardization of procedures is needed to validate such biomarkers for the longitudinal monitoring of arterial hypertension and other diseases.

Functional and Morphologic Findings at Four Years After Intravitreal Bevacizumab or Laser for Type 1 ROP

BACKGROUND AND OBJECTIVE

To compare morphologic and functional status at age 4 years for patients treated in one eye with laser photocoagulation and the other eye with intravitreal bevacizumab (IVB) injection for Type 1 retinopathy of prematurity (ROP).

PATIENTS AND METHODS

In this single-center, randomized, controlled trial, best-corrected visual acuity (BCVA) in logMAR was obtained along with spherical equivalent refraction (SER), fluorescein angiography (FA), optical coherent tomography (OCT), and OCT angiography (OCTA).

RESULTS

Eighteen babies (36 eyes) were selected for this study. BCVA and SER were similar in the two groups, but six patients had anisometropia of 4 diopters or more. IVB-treated eyes tended to have thinner foveal thickness than laser-treated eyes (mean difference: -5.33 pixels; 95% confidence interval, -9.62 to -1.05).

CONCLUSION

Although the differences found here are minimal between the IVB-treated and laser-treated groups, further long-term evaluation of not only FA, but also OCT and OCTA, are needed in larger studies. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:180-186.].

The Fovea in Retinopathy of Prematurity

Purpose

Because preterm birth and retinopathy of prematurity (ROP) are associated with poor visual acuity (VA) and altered foveal development, we evaluated relationships among the central retinal photoreceptors, postreceptor retinal neurons, overlying fovea, and VA in ROP.

Methods

We obtained optical coherence tomograms (OCTs) in preterm born subjects with no history of ROP (none; n = 61), ROP that resolved spontaneously without treatment (mild; n = 51), and ROP that required treatment by laser ablation of the avascular peripheral retina (severe; n = 22), as well as in term born control subjects (term; n = 111). We obtained foveal shape descriptors, measured central retinal layer thicknesses, and demarcated the anatomic parafovea using automated routines. In subsets of these subjects, we obtained OCTs eccentrically through the pupil (n = 46) to reveal the fiber layer of Henle (FLH) and obtained adaptive optics scanning light ophthalmograms (AO-SLOs) of the parafoveal cones (n = 34) and measured their spacing and distribution.

Results

Both VA and foveal depth decreased with increasing ROP severity (term, none, mild, severe). In severe subjects, foveae were broader than normal and the parafovea was significantly enlarged compared to every other group. The FLH was thinner than normal in mild (but not severe) subjects. VA was associated with foveal depth more than group. Density of parafoveal cones did not differ significantly among groups.

Conclusions

Foveal structure is associated with loss of VA in ROP. The preserved FLH in severe (relative to mild) eyes suggests treatment may help cone axon development. The significantly larger parafovea and increased outer nuclear layer (ONL) thickness in ROP hint that some developmental process affecting the photoreceptors is not arrested in ROP but rather is supranormal.

Advances in multimodal imaging in ophthalmology

Multimodality ophthalmic imaging systems aim to enhance the contrast, resolution, and functionality of existing technologies to improve disease diagnostics and therapeutic guidance. These systems include advanced acquisition and post-processing methods using optical coherence tomography (OCT), combined scanning laser ophthalmoscopy and OCT systems, adaptive optics, surgical guidance, and photoacoustic technologies. Here, we provide an overview of these ophthalmic imaging systems and their clinical and basic science applications.

Optical Coherence Tomography Angiography in Prematurity

Purpose: During normal foveal development there is a close interaction between the neurosensory and vascular elements of the fovea making it vulnerable to prematurity and retinopathy of prematurity (ROP). We aim to assess this potential effect on foveal development in preterms evaluated simultaneously with both optical coherence tomography (OCT) and OCT angiography (OCTA).Method: Unrestricted literature search in the PubMed and Cochrane library databases yielded 20 distinct citations. Fifteen were relevant and reviewed.Results: In preterms, OCTA demonstrated a significant decrease in the foveal avascular zone area and an increase in foveal vessel density. OCT showed a decrease in foveal pit depth and an increase in the thickness of the subfoveal retinal layers. Some studies correlated these changes with reduced vision.Conclusion: Changes in the vascular and neurosensory retina were found in premature children. It remains unclear whether this is related to prematurity alone or ROP and its treatment.

Foveal Differentiation and Inner Retinal Displacement Are Arrested in Extremely Premature Infants

Purpose

Children with a history of prematurity often have poorly developed foveae but when during development foveal differences arise. We hypothesize that the course of foveal development is altered from the time of preterm birth.

Methods

Eyes of 102 preterm infants undergoing retinopathy of prematurity screening examinations in the STudy of Eye imaging in Premature infantS (BabySTEPS) (NCT02887157) were serially imaged between 30 and 42 weeks postmenstrual age (PMA) using handheld optical coherence tomography systems. Total retinal thickness, inner retinal layer (IRL) thickness, and outer retinal layer (ORL) thickness were measured at the foveal center and parafovea. Foveal put depth, IRL thickness, and ORL thickness were compared between infants born at different gestational ages using mixed effects models.

Results

Foveal pit depth and IRL thickness were inversely related to gestational age; on average, the most premature infants had the thickest IRL and shallowest pits at all PMAs. Differences were evident by 30 weeks PMA and persisted through 42 weeks PMA. The foveal pits of the most premature infants did not progressively deepen, and the IRLs did not continue to thin with increasing chronological age.

Conclusions

Foveation in extremely preterm infants is arrested from the earliest observed ages and fails to progress through term equivalent age. The developmental displacement of the IRL from the foveal center into the parafovea does not occur normally after preterm birth. These observations suggest that foveal hypoplasia seen in children with history of prematurity is due to disturbances in foveal development that manifest within weeks of birth.

Translational Research in Retinopathy of Prematurity: From Bedside to Bench and Back Again

Retinopathy of prematurity (ROP), a vascular proliferative disease affecting preterm infants, is a leading cause of childhood blindness. Various studies have investigated the pathogenesis of ROP. Clinical experience indicates that oxygen levels are strongly correlated with ROP development, which led to the development of oxygen-induced retinopathy (OIR) as an animal model of ROP. OIR has been used extensively to investigate the molecular mechanisms underlying ROP and to evaluate the efficacy of new drug candidates. Large clinical trials have demonstrated the efficacy of anti-vascular endothelial growth factor (VEGF) agents to treat ROP, and anti-VEGF therapy is presently becoming the first-line treatment worldwide. Anti-VEGF therapy has advantages over conventional treatments, including being minimally invasive with a low risk of refractive error. However, long-term safety concerns and the risk of late recurrence limit this treatment. There is an unmet medical need for novel ROP therapies, which need to be addressed by safe and minimally invasive therapies. The recent progress in biotechnology has contributed greatly to translational research. In this review, we outline how basic ROP research has evolved with clinical experience and the subsequent emergence of new drugs. We discuss previous and ongoing trials and present the candidate molecules expected to become novel targets.

Update on the Use of Anti-VEGF Drugs in the Treatment of Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is one of the many significant consequences of premature birth and remains one of the leading causes of visual impairment in infants. Originally, cryotherapy was used to prevent the complications of vitreous hemorrhage and retinal detachment. Subsequently, laser photocoagulation, which is at least as effective and possibly safer than cryoretinopexy, was adopted as the primary treatment for type 1 ROP (stage 2 or 3 disease in zone II with plus disease or any stage disease in zone I with plus disease or stage 3 disease in zone I without plus disease). Laser therapy has been proven effective, and has a degree of permanence that is yet to be matched by alternative treatments, but can be associated with significant ocular side effects such as myopia. Treatment of type 1 ROP with anti-vascular endothelial growth factor (VEGF) agents seems to have fewer ocular side effects than laser ablation of the retina, particularly if used to treat type 1 ROP in zone I. However, ROP recurrence is a real threat after anti-VEGF therapy and long-term systemic side effects of this therapy remain under evaluation. This review focuses on the ophthalmic and systemic benefits and risks of anti-VEGF therapies for ROP as compared to retinal photocoagulation. Anti-VEGF therapies have dramatically altered the management of ROP and have also been shown to be beneficial with regard to the visual prognosis of patients with ROP, but patients so treated require frequent short- and long-term follow-up to detect and manage potential complications associated with this form of treatment. Such information also will allow clinicians to characterize the efficacy, side effect profile, and utility of intravitreal anti-VEGF agents for this condition. Prospective studies are needed to identify the optimum anti-VEGF drug and dose. [J Pediatr Ophthalmol Strabismus. 2020;57(6):351-362.].

Effect of Prematurity on Foveal Development in Early School-Age Children

PURPOSE

To evaluate the foveal development in preterm children with optical coherence tomography and OCT angiography.

DESIGN

Retrospective cohort study.

METHODS

This study included children aged 6-8 years who were born prematurely and who did not receive retinopathy treatment. They were evaluated between September 2018 and July 2019, categorized according to gestational age (GA) (group I: GA ≤30 weeks; group II: GA between 31 and 34 weeks), and compared with full-term children (group III). Central foveal thickness (CFT), inner retinal thickness (IRT), outer retinal thickness (ORT), subfoveal choroidal thickness (CT), temporal and nasal CT, foveal avascular zone (FAZ) diameter, and vessel densities of superficial (SCP-VD) and deep capillary plexuses (DCP-VD) of the foveal and parafoveal areas were examined in detail.

RESULTS

The study included 126 eyes of 63 patients (group I: 40 eyes; group II: 46 eyes; and group III: 40 eyes). In group I, CFT, IRT, ORT, foveal SCP-VD, and foveal DCP-VD were significantly greater than those in the other groups, and temporal CT and FAZ diameter were significantly lower (P < .05). GA showed a significant negative correlation with CFT, IRT, ORT, foveal SCP-VD, and foveal DCP-VD and a significant positive correlation with subfoveal CT, temporal and nasal CT, and FAZ diameter (P < .05).

CONCLUSION

The morphological and vascular foveal structures in early school-age children who were born premature were different from those of full-term children. These differences were correlated with GA and more pronounced in those with GA of ≤30 weeks.

POTENTIAL UTILITY OF FOVEAL MORPHOLOGY IN PRETERM INFANTS MEASURED USING HAND-HELD OPTICAL COHERENCE TOMOGRAPHY IN RETINOPATHY OF PREMATURITY SCREENING

PURPOSE

To investigate dynamic foveal morphology with postmenstrual age, in preterm infants with and without retinopathy of prematurity using hand-held optical coherence tomography, adjusting for gestational age (GA) and birthweight (BW).

METHODS

Prospective mixed cross-sectional/longitudinal observational study of 87 participants (23-36 weeks GA; n = 30 with, n = 57 without retinopathy of prematurity) using hand-held optical coherence tomography images (n = 278) acquired between 31 weeks and 44 weeks postmenstrual age excluding treated retinopathy of prematurity. Measurements included foveal width, area, depth, central foveal thickness, maximum slope, and parafoveal retinal thickness at 1,000 µm nasal and temporal to the central fovea.

RESULTS

Retinopathy of prematurity was significantly correlated with only foveal width in either GA or BW adjusted statistical models. In contrast, severity of prematurity (GA, BW) correlated with foveal area (P < 0.005), depth (P ≤ 0.001), and slope (P < 0.01), although central foveal thickness (P = 0.007) and parafoveal retinal thickness (P < 0.001) correlated with GA, but not with BW.

CONCLUSION

Foveal width is independent of GA and BW with potential in retinopathy of prematurity screening assessment using hand-held optical coherence tomography. Foveal morphology could be graded in prematurity during development, with possible implications for future management of preterm infants.

Assessing Ganglion Cell Layer Topography in Human Albinism Using Optical Coherence Tomography

Purpose

To test whether ganglion cell layer (GCL) and inner plexiform layer (IPL) topography is altered in albinism.

Methods

Optical coherence tomography scans were analyzed in 30 participants with albinism and 25 control participants. Horizontal and vertical line scans were acquired at the fovea, then strip registered and averaged. The Duke Optical Coherence Tomography Retinal Analysis Program was used to automatically segment the combined GCL and IPL and total retinal thickness, followed by program-assisted manual segmentation of the boundary between the GCL and IPL. Layer thickness and area under the curve (AUC) were calculated within 2.5 mm of the fovea. Nasal-temporal and superior-inferior asymmetry were calculated as an AUC ratio in each quadrant.

Results

GCL and IPL topography varied between participants. The summed AUC in all quadrants was similar between groups for both the GCL (P = 0.84) and IPL (P = 0.08). Both groups showed nasal-temporal asymmetry in the GCL, but only participants with albinism had nasal-temporal asymmetry in the IPL. Nasal-temporal asymmetry was greater in albinism for both the GCL (P < 0.0001) and the IPL (P = 0.0006). The GCL usually comprised a greater percentage of the combined GCL and IPL in controls than in albinism.

Conclusions

The GCL and IPL have greater structural variability than previously reported. GCL and IPL topography are significantly altered in albinism, which suggests differences in the spatial distribution of retinal ganglion cells. This finding provides insight into foveal development and structure-function relationships in foveal hypoplasia.

Misalignment of foveal pit and foveal bulge determined by ultrahigh-resolution SD-OCT in normal eyes

PURPOSE

The foveal bulge (FB) results from a lengthening of the outer segments of the photoreceptors which then makes the central fovea arcuate in shape. The purpose of this study was to evaluate the morphological features and locations of the FB relative to the foveal pit (FP) in a single B-scan image.

METHODS

One hundred and forty-seven eyes of 147 healthy volunteers were studied. Horizontal and vertical B-scan optical coherence tomographic (OCT) images through the fovea were recorded by an ultrahigh-resolution spectral domain OCT (UHR-SD-OCT) instrument (Bi-μ, KOWA, Japan). The vertex of the FB and the center of the FP were identified with the ImageJ software. The distance between the FB and FP and the height of the FB were measured.

RESULTS

In the horizontal images, the vertex of the FB was on the nasal side of the center of the FP in 97 eyes (66%), on the temporal side in 42 eyes (29%), and the same position in 8 eyes (5%). In the vertical images, the vertex of the FB was superior to the center of the FP in 82 eyes (55%), inferior to the center of the FP in 45 eyes (31%), and the same position in 20 eyes (14%). The mean distance (± SD) between the FB and the FP was + 16.8 ± 30.1 μm in the horizontal images and + 8.27 ± 28.0 μm in the vertical images. The mean height (± SD) of the FB was 77.0 ± 4.78 μm in the horizontal images and 77.9 ± 5.05 μm in the vertical images. The height of the FB in the horizontal images was significantly correlated with refractive error in the multiple regression analysis (P = 0.041).

CONCLUSIONS

These results indicate that the vertex of the FB was not aligned with the center of the FP in the majority of the eyes of normal Japanese individuals in a single B-scan image. Analysis showed that eyes with less severe myopia had the higher height of the FB. This must be considered when interpreting the location of the vertex of the FB and the center of the FP in clinical situations.

Comparison of the Morphology of the Foveal Pit Between African and Caucasian Populations

Purpose

The purpose of this study was to characterize foveal pit morphology in an African (Ghanaian) population, to compare it to that of a Caucasian group and to determine if it varied with age in the two populations.

Methods

The depth, diameter, slope, and volume of the foveal pit were interpolated from optical coherence tomography volume scans recorded in 84 Ghanaian and 37 Caucasian individuals. Their association with age, sex, and ethnicity was investigated using multilevel regression models.

Results

The foveal pit differed significantly in width, slope, and volume between Ghanaian men and women (P < 0.001), but only in width and volume between Caucasian men and women (P < 0.01). In Ghanaians, age was associated with a narrowing of the foveal depression and a reduction of its volume. Overall, these changes were more pronounced in women as compared to men and were largely absent from the Caucasian group. When controlled for age, the foveal pit of Ghanaians was significantly wider and larger in volume as compared to the Caucasian group (P < 0.001).

Conclusions

The morphology of the foveal pit differs between African and Caucasian individuals. These anatomic differences should be considered when examining differences in prevalence and clinical features of vitreoretinal disorders involving the fovea between the two populations.

Translational Relevance

Differences in retinal anatomy may partly explain variations in the prevalence and clinical features of retinal diseases between Africans and Caucasians. Such differences should be adequately considered in diagnoses and monitoring of ocular diseases in patients with African ancestry.

Comparison of OCT angiography in children with a history of intravitreal injection of ranibizumab versus laser photocoagulation for retinopathy of prematurity

Purpose

To compare the foveal microvascular structure characteristics in children with a history of intravitreal injection of ranibizumab (IVR) versus laser photocoagulation (LP) for retinopathy of prematurity by optical coherence tomography angiography (OCTA).

Methods

In this cross-sectional study, a total of 17 children (28 eyes) underwent IVR and 20 children (37 eyes) underwent LP were recruited. The age of doing OCTA examination of the two groups are 5.4±1.1 years and 6.3±1.8 years, respectively (p=0.07). Spectral-domain OCTA was performed for all the eyes with a scan size of 3×3 mm. The data of the superficial retinal layer were analysed. The foveal avascular zone (FAZ) and vessel density (including vessel length density (VLD) and perfusion density (PD)) were measured using the software of OCTA (Cirrus AngioPlex 5000, Carl Zeiss, Meditec, Dubin, California, USA). The central foveal thicknesses (CFT) were measured by cross-sectional OCT.

Results

In the central fovea, the retinal VLD and PD of patients with IVR were 13.82±2.99 mm/mm² and 0.25±0.05 mm²/mm², respectively, which were significantly lower than those of the LP group (15.64±2.71 mm/mm² and 0.28±0.05 mm²/mm², p=0.01 and p=0.006). The FAZ area of patients with IVR and LP were 0.13±0.09 mm² and 0.09±0.07 mm², respectively (p=0.048). The CFT of patients with IVR and LP were 200.7±16.7 µm and 220.9±22.7 µm, respectively (p<0.01). The logarithm of the minimal angle of resolution best-corrected visual acuity of patients with IVR and LP were 0.2±0.1 and 0.1±0.1, respectively (p=0.01). There was no significant difference in the parafoveal and foveal VLD and PD, FAZ morphological index and spherical equivalent refraction (SER) between the two groups.

Conclusion

The IVR might contribute to microvascular changes in the macular zone, such as reducing the central foveal VLD and PD, while the LP might contribute to microstructural changes, such as smaller FAZ and thicker CFT.

Can Structural Grading of Foveal Hypoplasia Predict Future Vision in Infantile Nystagmus?: A Longitudinal Study

PURPOSE

To evaluate structural grading and quantitative segmentation of foveal hypoplasia using handheld OCT, versus preferential looking (PL), as predictors of future vision in preverbal children with infantile nystagmus.

DESIGN

Longitudinal cohort study.

PARTICIPANTS

Forty-two patients with infantile nystagmus (19 with albinism, 17 with idiopathic infantile nystagmus, and 6 with achromatopsia) were examined.

METHODS

Spectral-domain handheld OCT was performed in preverbal children up to 36 months of age. Foveal tomograms were graded using our 6-point grading system for foveal hypoplasia and were segmented for quantitative analysis: photoreceptor length, outer segment (OS) length, and foveal developmental index (FDI; a ratio of inner layers versus total foveal thickness). Patients were followed up until they could perform chart visual acuity (VA) testing. Data were analyzed using linear mixed regression models. Visual acuity predicted by foveal grading was compared with prediction by PL, the current gold standard for visual assessment in infants and young children.

MAIN OUTCOME MEASURES

Grade of foveal hypoplasia, quantitative parameters (photoreceptor length, OS length, FDI), and PL VA were obtained in preverbal children for comparison with future chart VA outcomes.

RESULTS

We imaged 81 eyes from 42 patients with infantile nystagmus of mean age 19.8 months (range, 0.9-33.4 months; standard deviation [SD], 9.4 months) at the first handheld OCT scan. Mean follow-up was 44.1 months (range, 18.4-63.2 months; SD, 12.0 months). Structural grading was the strongest predictor of future VA (grading: r = 0.80, F = 67.49, P < 0.0001) compared with quantitative measures (FDI: r = 0.74, F = 28.81, P < 0.001; OS length: r = 0.65; F = 7.94, P < 0.008; photoreceptor length: r = 0.65; F = 7.94, P < 0.008). Preferential looking was inferior to VA prediction by foveal grading (PL: r = 0.42, F = 3.12, P < 0.03).

CONCLUSIONS

Handheld OCT can predict future VA in infantile nystagmus. Structural grading is a better predictor of future VA than quantitative segmentation and PL testing. Predicting future vision may avert parental anxiety and may optimize childhood development.

Can Structural Grading of Foveal Hypoplasia Predict Future Vision in Infantile Nystagmus?: A Longitudinal Study

Purpose

To evaluate structural grading and quantitative segmentation of foveal hypoplasia using handheld OCT, versus preferential looking (PL), as predictors of future vision in preverbal children with infantile nystagmus.

Design

Longitudinal cohort study.

Participants

Forty-two patients with infantile nystagmus (19 with albinism, 17 with idiopathic infantile nystagmus, and 6 with achromatopsia) were examined.

Methods

Spectral-domain handheld OCT was performed in preverbal children up to 36 months of age. Foveal tomograms were graded using our 6-point grading system for foveal hypoplasia and were segmented for quantitative analysis: photoreceptor length, outer segment (OS) length, and foveal developmental index (FDI; a ratio of inner layers versus total foveal thickness). Patients were followed up until they could perform chart visual acuity (VA) testing. Data were analyzed using linear mixed regression models. Visual acuity predicted by foveal grading was compared with prediction by PL, the current gold standard for visual assessment in infants and young children.

Main Outcome Measures

Grade of foveal hypoplasia, quantitative parameters (photoreceptor length, OS length, FDI), and PL VA were obtained in preverbal children for comparison with future chart VA outcomes.

Results

We imaged 81 eyes from 42 patients with infantile nystagmus of mean age 19.8 months (range, 0.9–33.4 months; standard deviation [SD], 9.4 months) at the first handheld OCT scan. Mean follow-up was 44.1 months (range, 18.4–63.2 months; SD, 12.0 months). Structural grading was the strongest predictor of future VA (grading: r = 0.80, F = 67.49, P < 0.0001) compared with quantitative measures (FDI: r = 0.74, F = 28.81, P < 0.001; OS length: r = 0.65; F = 7.94, P < 0.008; photoreceptor length: r = 0.65; F = 7.94, P < 0.008). Preferential looking was inferior to VA prediction by foveal grading (PL: r = 0.42, F = 3.12, P < 0.03).

Conclusions

Handheld OCT can predict future VA in infantile nystagmus. Structural grading is a better predictor of future VA than quantitative segmentation and PL testing. Predicting future vision may avert parental anxiety and may optimize childhood development.

Structural consequences of arrested foveal development in preterms with persisting signs of immaturity

Purpose

To evaluate the impact of structural changes in a limited sample of adult preterms with foveal immaturity from optical coherence tomography (OCT) B-scan images and to estimate layer displacement and changes in areal and volume magnification within the inner fovea.

Subjects and methods

Layer thickness was measured in conventional and directional OCT scans from eight preterms with different degrees of foveal immaturity (24–33 weeks of gestation, 22–33 years of age) and five controls (20–33 years of age). We obtained reflectivity profiles of the outer plexiform layer (OPL) and manual segmentation data of the inner nuclear layer (INL) and the combined ganglion cell layer (GCL) and inner plexiform layer (IPL) at specified eccentricities from 300 to 900 µm. Displacement of cumulative thickness curves of preterms compared with that of the controls was used to estimate retardation of layer displacement. Changes in areal magnification and layer thickness were used to construct a structural model of redistribution within the fovea of preterms.

Results

Retardation of centrifugal layer displacement of OPL and all inner retinal layers (IRL) was marked in both preterm groups with foveal immaturity, whereas retardation was marginal in the preterm group without clinical signs of immaturity. Retarded displacement within the IRL and OPL had a major impact on available space within the central fovea.

Conclusions

A marked retardation of displacement was demonstrated for all IRL within the immature fovea of preterms with decreased areal and volume magnification and reduced space available for synaptic communication coupled to the degree of immaturity.

Direct modeling of foveal pit morphology from distortion-corrected OCT images

Inherent distortions affect the spatial geometry of optical coherence tomography (OCT) images and consequently the foveal pit dimensions. Distortion correction provides an accurate anatomical representation of the retinal shape. A novel approach that automatically extracts foveal pit metrics from distortion-corrected OCT images using a sum of Gaussian function is presented. Foveal width, depth and slope were determined in 292 eyes with low fitting errors and high repeatability. Comparisons to undistorted scans revealed significant differences. To conclude, the internal OCT distortions affect the measurements of the foveal pit with their correction providing further insights into the role of foveal morphology in retinal pathologies and refractive development.

[Foveal avascular zone and OCT angiography. An overview of current knowledge]

BACKGROUND

The foveal avascular zone (FAZ) has often been analyzed under different aspects in the last decades, mainly by fluorescence angiography (FA); however, the novel technology of optical coherence tomography angiography (OCTA) enables a non-invasive examination, visualization and quantitative analysis of the FAZ, which has recently led to many new findings, especially in a multidisciplinary manner. This article provides an overview of the investigation of the FAZ using OCTA and the new findings that have been obtained using OCTA in recent years.

METHODS

This article is based on a comprehensive literature review.

RESULTS

In many studies a good reproducibility and repeatability of the FAZ measurements by OCTA could be proven, also by comparing different OCTA devices. In patients with ocular pathologies and systemic diseases, e. g. after retinal vein occlusion or retinal surgery and in patients with diabetes mellitus without diabetic retinopathy, differences to healthy control groups and correlations to visual function could be shown. Moreover, in patients with neurological diseases, such as Alzheimer's dementia, changes of the FAZ could be identified.

CONCLUSION

The OCTA is a non-invasive technology, which enables a reliable visualization and reproducible quantification of the FAZ. The size of the FAZ seems to be altered in different retinal and systemic diseases, which also may correlate with visual function; however, long-term studies evaluating the diagnostic value of these changes in the course of the disease are currently lacking.

The Size of the Foveal Avascular Zone Is Associated with Foveal Thickness and Structure in Premature Children

Purpose

To investigate the foveal avascular zone (FAZ) in the eyes of patients with a history of retinopathy of prematurity (ROP) using optical coherence tomography angiography (OCTA) and to identify associated clinical factors.

Patients and methods

Overall, 14 children with a history of laser treatment for ROP, 17 children born prematurely without a history of ROP, and 41 age-matched children born at full-term (age range 7–14 years) were included. OCTA was conducted on an area measuring 3 × 3 mm in the central macula. The area of FAZ in the superficial layer was measured. Foveal thickness (FT), ganglion cell complex thickness, and the presence of inner retinal layer (IRL) at the fovea were evaluated.

Results

There were significant differences in FT and FAZ size among patients (P < 0.001). The eyes of patients that had been treated for ROP showed the smallest FAZ and greatest FT. Univariate analyses demonstrated that the area of FAZ was not correlated with visual acuity (P=0.078) but with gestational age (GA) (P=0.001), birth weight (P=0.013), the presence of IRL (P < 0.001), and FT (P < 0.001). Multivariate regression analyses showed that the area of FAZ was significantly associated with GA, the presence of IRL, and FT (P=0.03, P=0.01, P < 0.001, respectively).

Conclusion

The eyes of preterm children had small FAZ, and this reduction in area was associated with greater FT, the presence of IRL, and lower GA.

Foveal Development After Use of Bevacizumab for Aggressive Posterior Retinopathy of Prematurity

Foveal development can occur after intravitreal bevacizumab (IVB) treatment for aggressive posterior retinopathy of prematurity (APROP). A 1,310 g male twin, born at 31 weeks, was diagnosed with APROP and undeveloped fovea at 33 weeks. IVB was injected in both eyes. Unfortunately, multiple surgical interventions were required to treat retinal detachment in the left eye, at which time, foveal development was studied in the right eye. Imaging revealed development of foveal capillary ring, avascular zone, and shallow pit. Although bevacizumab is an inhibitor of angiogenesis and delays vascular advancement, development of foveal capillary vascular network with foveal avascular zone and pit can proceed despite multiple treatments. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:e185-e187.].

Fundus-Controlled Dark Adaptometry in Young Children Without and With Spontaneously Regressed Retinopathy of Prematurity

PURPOSE

We correlate dark adaptation course with foveal morphologic alterations in preterm and term-born children using a modified fundus-controlled perimeter and spectral domain-optical coherence tomography (SD-OCT) imaging.

METHODS

We performed fundus-controlled chromatic dark adaptometry in premature children aged 6 to 13 years without retinopathy of prematurity (no-ROP; n = 61) and with spontaneously regressed ROP (sr-ROP, n = 29), and in 11 age-matched term-born children. The degree of macular developmental arrest (MDA), defined as a disproportion of the outer nuclear layer to inner retinal layers in the fovea (ONL+/IRL-ratio), was analyzed with the DiOCTA tool in SD-OCT scans.

RESULTS

Children with MDA showed a flatter dark adaptation course progression with a significant rod-mediated sensitivity recovery delay (0.0113 vs. 0.0253 dB/s; P < 0.001). Preterm-born children with regular foveal morphology reached the final rod-mediated dark-adapted threshold at 12 minutes after bleach at 18.8 dB, compared to after 18.7 minutes at 17.6 dB in children with MDA (no significant difference in final threshold; P = 0.773). The cone-mediated dark adaptation progression showed a significant lower final threshold in children with MDA (6.0 vs. 8.1 dB; P = 0.004).

CONCLUSIONS

Changes in dark adaptation were seen in the presence of MDA observed in premature children in the no-ROP and sr-ROP groups. MDA in former premature children is associated with functional deficits of cone and rod photoreceptor visual pathways.

TRANSLATIONAL RELEVANCE

Morphologic alterations in the central retina of premature children, evident in SD-OCT, are associated with long-term functional deficits in the rod and cone pathways, particularly evident in the rod dark adaptation course measured at 12° eccentricity. This indicates a more widespread retinal functional pathology not limited to the fovea, but occurring together with foveal alterations best defined as MDA.

Flicker electroretinogram recorded with portable ERG device in prematurely born schoolchildren with and without ROP

PURPOSE

The purpose of this study was to compare electroretinographic (ERG) responses of preterm schoolchildren, with and without a history of retinopathy of prematurity (ROP) with those of full-term schoolchildren by using a portable ERG device (RETeval system).

METHODS

Twenty five prematurely born schoolchildren with a mean gestational age of 27 + 1/7w (range 23-30w) and a mean birth weight of 1030 g (range 580-1700 g) who were 6.9 ± 2.2 years old participated in the study (premature group). A further subdivision according to a history of ROP (ROP+ group) or its absence (ROP- group) was introduced. Twenty eight healthy full-term schoolchildren with an average age of 8.6 ± 1.9 years participated as the control group. 30-Hz flicker ERG responses were obtained, and implicit times and amplitudes were compared between the groups.

RESULTS

30-Hz flicker ERG implicit times showed a significant difference between all three groups of children. The mean value of the implicit time in the term group was 25.76 ± 0.9 ms, whereas in the preterm ROP + group it was 28.96 ± 1.0 ms and in the preterm ROP- group it was 26.87 ± 1.5 ms. 30-Hz flicker ERG amplitudes did not show significant difference between term children and children born prematurely with or without ROP.

CONCLUSIONS

Prematurely born schoolchildren exhibit longer implicit time of the 30-Hz flicker ERG response compared to controls, suggesting a possible abnormality of the retinal cone system function. Under such circumstances, portable ERG device might be used clinically as a screening tool for retinal function evaluation in prematurely born children.

Assessing Retinal Structure in Patients with Parkinson's Disease

Objective:

The retina is an extension of the central nervous system (CNS), and ocular symptoms can precede manifestations of CNS disorders. Given that several neurodegenerative conditions that affect the brain exhibit ocular symptoms, the retina may be an accessible biomarker to monitor disease progression. Dopamine, the key neurotransmitter related to Parkinson’s disease (PD), is contained in amacrine and interplexiform cells, which reside in specific retinal layers. Understanding how loss of dopaminergic cells affects retinal anatomy could be relevant for monitoring disease progression. Here, our objective is to evaluate retinal structure (foveal pit morphology and thickness) in patients with PD.

Methods:

Thirty-three Caucasian subjects diagnosed with PD and 40 age-matched Caucasian control subjects underwent retinal imaging with spectral-domain optical coherence tomography (SD-OCT). Axial length measurements were used to correct the lateral scale of each macular volume scan. From these corrected volumes, foveal morphology was quantified with previously described algorithms, and Early Treatment Diabetic Retinopathy Study (ETDRS) grids of retinal thickness were generated and incorporated into a logistic regression model to predict PD.

Results:

Interocular foveal morphology measurements were highly symmetrical in PD patients and control subjects. There were no significant differences in foveal pit morphology between PD patients and control subjects. Using a model incorporating sex and axial length corrected ETDRS regions, we generated a receiver operating characteristic curve with a C-statistic of 0.80.

Conclusion:

Our study, which to our knowledge is the first to properly scale OCT measurements when quantifying retinal thickness, demonstrates that PD patients retain foveal symmetry between eyes. When constructing a model to predict PD, sex, along with the center 1 mm and temporal outer ETDRS regions, were significant predictors of PD. In addition to proper scaling of OCT measures, gender and racial differences in retinal anatomy should be considered in building future predictive PD models when using OCT.

Combining multimodal adaptive optics imaging and angiography improves visualization of human eyes with cellular-level resolution

Visualizing the cellular manifestation of disease has recently been aided by an increasing number of adaptive optics (AO)-based imaging modalities developed for the living human eye. However, simultaneous visualization of multiple, interacting cell types within a complete neural-epithelial-vascular complex has proven challenging. By incorporating AO with indocyanine green angiography, we demonstrate the possibility of imaging photoreceptors, retinal pigment epithelial cells, and choriocapillaris in the living human eye. Unexpectedly, we found that there was uptake of indocyanine green dye into the retinal pigment epithelial cells in the earliest phases of imaging, which formed the basis for devising a strategy to visualize the choriocapillaris. Our results expand the range of applications for an existing, FDA-approved, systemically injected fluorescent dye. The combined multimodal approach can be used to evaluate the complete outer retinal complex at the cellular level, a transformative step toward revealing the in vivo cellular status of neurodegenerative conditions and blinding diseases.

Relationship between the morphology of the foveal avascular zone, retinal structure, and macular circulation in patients with diabetes mellitus

Diabetic Retinopathy (DR) is an extremely severe and common degenerative disease. The purpose of this study was to quantify the relationship between various parameters including the Foveal Avascular Zone (FAZ) morphology, retinal layer thickness, and retinal hemodynamic properties in healthy controls and patients with diabetes mellitus (DM) with and with no mild DR (MDR) using Spectral-Domain Optical Coherence Tomography (Spectralis SDOCT, Heidelberg Engineering GmbH, Germany) and the Retinal Function Imager (Optical Imaging, Ltd., Rehovot, Israel). Our results showed a higher FAZ area and diameter in MDR patients. Blood flow analysis also showed that there is a significantly smaller venous blood flow velocity in MDR patients. Also, a significant difference in roundness was observed between DM and MDR groups supporting the development of asymmetrical FAZ expansion with worsening DR. Our results suggest a potential anisotropy in the mechanical properties of the diabetic retina with no retinopathy that may trigger the FAZ elongation in a preferred direction resulting in either thinning or thickening of intraretinal layers in the inner and outer segments of the retina as a result of autoregulation. A detailed understanding of these relationships may facilitate earlier detection of DR, allowing for preservation of vision and better clinical outcomes.

[Electrophysiological characteristics of the retina in children with cicatrical retinopathy of prematurity]

Visual impairment in children with regressive retinopathy of prematurity (ROP) are diverse and widespread.

PURPOSE

to describe the electrophysiological characteristics of the retina in children with I-V stages of regressive ROP.

MATERIAL AND METHODS

The study included children with stages I-V aged 5 to 17 (in the disease stages of IV and V - with reattachment of the retina after surgical treatment of its detachment). Patients with concomitant diseases of the eye were excluded from the study. The main group included 133 children (163 eyes) aged 5 to 17 (mean age 7.2±0.3). Gestation age was 30.0±0.2 weeks, birth weight - 1368.0±46.6g. The control group consisted of 55 age-matched children. Standard electroretinogram (ERG) was performed in all study subjects. The amplitude-time characteristics of maximum and photopic response a- and b-waves were evaluated, and the b/a-index was calculated.

RESULTS

Visual acuity of 0.6 or higher was observed in 18 eyes (54.5%) of children with stage I-II ROP and significantly less in the disease stages of III and IVa - 29.5% and 15.6% respectively (p<0.01: Φ=2,717-3,663). In patients with IVb-V stages in 94.1% of cases visual acuity was lower than 0.1. Anamnesis showed significant decrease in photopic ERG starting with active period of stage III ROP. The retinal function further progressively decreased with stages. b/a index of maximum ERG increased proportionally to the severity of ROP active period. Core b/a index was significantly reduced in all stages of ROP (p<0.05).

CONCLUSION

Even the early stages of ROP have consequences for the functional status of the retina in premature infants; it is accompanied by significant disturbance of its electrogenesis.

Clinical relevance of retinal structure in children with laser-treated retinopathy of prematurity versus controls - using optical coherence tomography

PURPOSE

We aimed to assess the macular anatomy using spectral domain optical coherence tomography (SD-OCT), in children born preterm who had laser-treated retinopathy of prematurity (ROP), and to investigate the relationship between structural changes in macula and visual function.

METHODS

Thirty-seven 3-8 years old children were included in the study in two groups: 20 children born preterm [(<34 weeks of gestation, birthweight (BW) <2000 g)] who had laser-treated ROP in the Neonatology Department, Municipal Clinical Emergency Hospital of Timisoara, Romania; and 17 controls (children born at term, without eye disease, matched for age and gender). Spectral domain optical coherence tomography (SD-OCT) imaging (Spectralis OCT) was performed at central fovea and 1 mm nasally.

RESULTS

In the ROP group (total 34 eyes), we included both eyes in 14 children, and on one eye in six other children. In the control group, both eyes for all 17 children were included. Central fovea thickness (CFT) was significantly higher in children born preterm and with laser-treated ROP as compared to controls (275 ± 34.8 μm versus 224 ± 27.2 μm; p < 0.001). The laser-treated eyes with ROP had mean best-corrected visual acuity (BCVA) = 0.19 logMAR (20/31 Snellen); 35% had BCVA ≥0.3 logMAR (20/40 Snellen). In receiver operating characteristic curve (ROC) analysis, with BCVA as static variable (category 0 = BCVA ≤0.3 logMAR), the CFT cut-off was 257 μm (sensitivity: 0.917; specificity: 0.661; area under the curve: 0.810, p = 0.001).

CONCLUSION

Years after the laser intervention, central fovea was significantly thicker in ROP laser-treated children born preterm when compared to controls. Central fovea thickness (CFT) correlated strongly and inversely with BW and gestational age (GA) at birth, while a CFT value above 257 μm was suggestive for suboptimal visual acuity. The proposed cut-off value needs to be validated in future larger studies.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF THE FOVEA IN CHILDREN BORN PRETERM

PURPOSE

To compare the foveal avascular zone (FAZ) area measured by optical coherence tomography angiography in children who had been born preterm with age-matched controls.

METHODS

In this cross-sectional observational comparative case series, 43 eyes of 26 children (28 eyes of 15 former preterm infants and 15 eyes of 11 former term infants) between the ages of 4 and 12 years old were included. Optical coherence tomography angiography with a scan size of 3 × 3 was performed for all eyes. Foveal avascular zone area was measured using the Optovue RTVue AVANTI instrument (Optovue Inc, Fremont, CA) software. Inner and outer retinal thicknesses were measured with the instrument caliper.

RESULTS

A distinct FAZ was absent in 12 eyes (42.8%) of children with a history of preterm birth, however, it was present in all (100%) control eyes. The FAZ area was significantly correlated with gestational age (r = 0.82, P < 0.001) and birth weight (r = 0.80, P < 0.001). The gestational age was less than 29 weeks and birth weight was less than 1,480 grams in eyes with no distinct FAZ. Mean central foveal vessel density in the superficial capillary plexus was 41.8 ± 4.4% in the preterm group and 32.8 ± 5.8% in the control group (P < 0.001). In all eyes, a significant negative correlation was found between the central foveal vessel density and gestational age (r = -0.63, P = 0.001) and birth weight (r = -0.59, P = 0.002). On spectral domain optical coherence tomography examination, the foveal depression was absent and the inner retinal layers were preserved in all eyes with absent FAZ. In all eyes, a significant negative correlation was found between the inner retinal thickness and gestational age (r = -0.68, P < 0.001) and birth weight (r = -0.61, P = 0.001). Ten eyes of 6 preterm children had a history of laser therapy for retinopathy of prematurity. A distinct FAZ was absent in six eyes (60%) with retinopathy of prematurity with history of laser therapy, and six eyes (33.3%) with preterm birth without laser therapy. Eyes with history of laser therapy had a statistically significantly higher inner retinal thickness and central foveal vessel density and smaller FAZ compared with the eyes with preterm birth without laser therapy (P < 0.001, P = 0.04 and P = 0.03, respectively).

CONCLUSION

Optical coherence tomography angiography is a novel modality for noninvasive visualization of the retinal vasculature in pediatric patients and expands our knowledge of foveal abnormalities in retinopathy of prematurity. A small or absent FAZ seems to be a distinct sign of prematurity.

Foveal Development in Infants Treated with Bevacizumab or Laser Photocoagulation for Retinopathy of Prematurity

PURPOSE

To characterize and quantify early foveal development in preterm infants and to compare this development between eyes treated with intravitreal bevacizumab or laser photocoagulation (LPC) and untreated eyes.

DESIGN

Observational case series.

PARTICIPANTS

One hundred thirty-one preterm infants undergoing retinopathy of prematurity (ROP) screenings.

METHODS

Handheld OCT imaging was performed longitudinally on all patients. Thickness measurements of the inner and outer retinal layers were obtained at the foveal center and the nasal and temporal foveal rims. Comparisons between treated and untreated eyes were adjusted for age and other confounding variables.

MAIN OUTCOME MEASURES

Weekly change in inner and outer retinal thickness and presence of inner retinal layers, ellipsoid zone (EZ), and cystoid macular changes (CMCs).

RESULTS

Outer retinal thickness at the foveal center increased by 3.1 μm/week in untreated eyes and 7.2 μm/week in bevacizumab-treated eyes (P = 0.038). Eyes treated with LPC had a lower probability of having all inner retinal layers present at the foveal center (odds ratio, 0.04; P = 0.001) and a lower probability of having the EZ present at the foveal center (odds ratio, 0.07; P = 0.024) compared with untreated eyes. Cystoid macular changes were found in 53% of patients and 22% of imaging sessions. The age-adjusted incidence of CMCs was not correlated with bevacizumab or LPC treatment.

CONCLUSIONS

Intravitreal bevacizumab therapy for ROP is associated with more rapid outer retinal thickening at the foveal center, whereas LPC is associated with earlier extrusion of the inner retinal layers and delayed development of the EZ at the foveal center. Long-term follow-up is needed to determine the visual significance of these findings.