Hypoglossal Canal Dural Arteriovenous Fistula: A Rare Cause of Ocular Proptosis.

It is exceedingly rare for dural arteriovenous fistulae (DAVFs) outside of the cavernous sinus to present with ophthalmological symptoms and signs. Hypoglossal canal DAVFs (HC-DAVFs) have only previously been reported as individual cases or small case series. Further, only an estimated 31% of HC-DAVFs present with ophthalmological findings. We report a noteworthy case of an HC-DAVF in a 74-year-old male who presented with proptosis, chemosis, and reduced visual acuity. He was treated endovascularly with liquid embolic filling. This report aims to highlight HC-DAVF as an important differential diagnosis for patients presenting with symptoms suggestive of arterialisation of the ophthalmic veins.

Retinal development in albinism: a prospective study using optical coherence tomography in infants and young children.

BACKGROUND: Retinal development normally involves migration of the inner retinal layers away from the fovea, migration of the cone photoreceptors into the fovea, and elongation of the photoreceptors over time. This process is arrested prematurely in albinism. However, because retinal development continues at least until the age of 4 years, when development arrests in albinism is uncertain. In this study we outlined the time course of retinal development in children with albinism. METHODS: We studied 44 children with a diagnosis of albinism and 223 control participants. All participants were aged between 0 and 6 years. We obtained 219 mixed cross-sectional and longitudinal optical coherence tomography examinations in the albinism group and compared them with 558 control examinations. Retinal layer segmentation was performed with ImageJ software. Generalised linear mixed regression modelling was used to analyse group differences in retinal development. FINDINGS: In the albinism group, inner retinal layer migration from the fovea was delayed and arrested prematurely, resulting in a significantly thicker central macular thickness than in the control group (p<0·0001). Whereas the central macular thickness increased with age in the control group, in the albinism group it initially decreased with age as a result of continuing regression of the inner retinal layers (p=0·041). The perifoveal retinal thickness was significantly decreased in albinism from a reduction of both inner (p<0·0001) and outer (p<0·0001) retinal layer thicknesses. There was evidence that the photoreceptor layers across the fovea were elongating in albinism, albeit at a reduced rate, compared with the control group. This difference was most apparent for the foveal photoreceptor inner segment (p=0·001). INTERPRETATION: Our findings show that perturbations exist in several aspects of retinal development including the migration and differentiation of the neuronal cells within the retina. We showed continuing regression of the inner retinal layers and elongation of the photoreceptor layers suggesting residual plasticity of the developing albino retina. This finding is important because treatment at the earliest stages of the condition might normalise retinal development and optimise vision. FUNDING: UK Medical Research Council (grant number MR/J004189/1), Ulverscroft Foundation, National Eye Research Centre, Nystagmus Network UK.

High-Resolution Imaging of the Optic Nerve and Retina in Optic Nerve Hypoplasia.

PURPOSE: To investigate the optic nerve and macular morphology in patients with optic nerve hypoplasia (ONH) using spectral-domain optical coherence tomography (SD OCT). DESIGN: Prospective, cross-sectional, observational study. SUBJECTS: A total of 16 participants with ONH (10 female and 6 male; mean age, 17.2 years; 6 bilateral involvement) and 32 gender-, age-, ethnicity-, and refraction-matched healthy controls. METHODS: High-resolution SD OCT (Copernicus [Optopol Technology S.A., Zawiercie, Poland], 3 µm resolution) and handheld SD OCT (Bioptigen Inc [Research Triangle Park, NC], 2.6 µm resolution) devices were used to acquire horizontal scans through the center of the optic disc and macula. MAIN OUTCOME MEASURES: Horizontal optic disc/cup and rim diameters, cup depth, peripapillary retinal nerve fiber layer (RNFL), and thickness of individual retinal layers in participants with ONH and in controls. RESULTS: Patients with ONH had significantly smaller discs (P < 0.03 and P < 0.001 compared with unaffected eye and healthy controls, respectively), horizontal cup diameter (P < 0.02 for both), and cup depth (P < 0.02 and P < 0.01, respectively). In the macula, significantly thinner RNFL (nasally), ganglion cell layer (GCL) (nasally and temporally), inner plexiform layer (IPL) (nasally), outer nuclear layer (ONL) (nasally), and inner segment (centrally and temporally) were found in patients with ONH compared with the control group (P < 0.05 for all comparisons). Continuation of significantly thicker GCL, IPL, and outer plexiform layer in the central retinal area (i.e., foveal hypoplasia) was found in more than 80% of patients with ONH. Clinically unaffected fellow eyes of patients with ONH showed mild features of underdevelopment. Visual acuity and presence of septo-optic dysplasia were associated with changes in GCL and IPL. Sensitivity and specificity for the detection of ONH based on disc and retinal optical coherence tomography (OCT) parameters were >80%. CONCLUSIONS: Our study provides evidence of retinal changes in ONH. In addition to thinning of retina layers mainly involving the RNFL and GCL, signs reminiscent of foveal hypoplasia were observed in patients with ONH. Optic nerve and foveal parameters measured using OCT showed high sensitivity and specificity for detecting ONH, demonstrating their useful for clinical diagnosis.

Macular morphology in patients with optic nerve head drusen and optic disc edema.

PURPOSE: In this study we investigated macular morphology, including individual retinal layers, in patients with optic nerve head drusen (ONHD) and optic disc edema (ODE) compared with healthy participants, using high-resolution spectral domain optical coherence tomography (OCT). DESIGN: Prospective, cross-sectional, observational study. PARTICIPANTS: A total of 67 patients with ONHD, 36 patients with ODE, and 57 healthy participants. METHODS: High-resolution spectral domain OCT (Copernicus [OPTOPOL Technology S.A., Zawiercie, Poland] 3-µm resolution, 7 × 7 × 2-mm volumetric scans) was used to image macula morphology. Average retinal nerve fiber layer (RNFL) thickness was measured using a semiautomated method with manual correction of the internal limiting membrane, RNFL, and retinal pigment epithelium (RPE). Retinal and RNFL thicknesses were measured and analyzed in 3 circular zones (Early Treatment Diabetic Retinopathy Study protocol). Individual retinal layers at the macula were quantified by analyzing tomograms using ImageJ (http://rsbweb.nih.gov/ij/; Accessed June 1, 2013). MAIN OUTCOME MEASURES: Average retinal and individual retinal layer thickness in patients with ODE or ONHD, and healthy controls. RESULTS: Patients with ONHD had thicker retinae in the inner annulus compared with patients with ODE and controls (significant in the temporal segment compared with those with ODE [P = 0.013] and in the superior segment compared with controls [P = 0.05]). Patients with ONHD had a significantly thinner inner plexiform layer (IPL) (P = 0.02), nerve fiber layer (P = 0.05), and RPE (P = 0.0001), and thicker ganglion cell layer (P = 0.003) and outer plexiform layer (OPL) (P < 0.001) compared with controls. Patients with ODE demonstrated the thickest retina and RNFL in the outer annulus (significant in the inferior segment compared with controls, P = 0.02 for both) with significant thickening in the IPL (P = 0.004), OPL (P < 0.003), and outer segment layer (P ≤ 0.02), and severe ganglion cell loss (P = 0.004) and RPE (P = 0.0001) thinning compared with healthy volunteers. CONCLUSIONS: Our study shows that optic nerve diseases are associated with selective changes in different retinal layers in patients with ODE and ONHD. These findings may be of diagnostic value and could be taken into consideration in assessing patients and studying the pathogenesis of these conditions.

Gender- and Ethnicity-Related Differences in Optic Nerve Head Topography in Healthy Indian and Caucasian Participants.

We investigated the effect of ethnicity and gender on optic nerve head morphology in healthy subjects using spectral-domain optical coherence tomography (SD-OCT). Thirty-five Indian (i.e. Indian subcontinent) females, 34 Caucasian females, 32 Indian males, and 32 Caucasian males were examined using SD-OCT (Copernicus, Optopol Technology). Disc and rim areas were larger in Caucasian males compared with females but smaller in Indians males compared with females. Indian participants had significantly larger cup areas and volumes without significant differences in retinal nerve fibre layer (RNFL) thicknesses between groups. Gender and ethnicity differences should be considered in assessment of patients.

Short-term progression of optic disc and macular changes in optic nerve head drusen.

PURPOSE: To quantify in patients with optic nerve head drusen (ONHD)changes after 1-year observation in: (i) optic disc and (ii) macular optical coherence tomography (OCT) parameters and (iii) the effect of age at enrolment in the study. DESIGN: Prospective, cross-sectional observational study using Spectral Domain-OCT (Copernicus; OPTOPOL Technology S.A., Zawiercie, Poland) imaging was carried out in 35 patients with ONHD (age-42.8 ± 19.9 years; males = 15; females = 20) at baseline and after 12 months follow-up. RESULTS: Patients with ONHD had significant thinning of the surface nerve fibre layer in the central (p = 0.03), superior (p = 0.05) and inferior (p = 0.04) areas; mean ppRNFL thinning (p = 0.0 4) and ppRNFL thinning in the nasal segment (p = 0.028). Retinal thinning in the central (p = 0.001), inner (p = 0.01) and outer (p = 0.002) temporal, outer superior (p = 0.03) and inferior (p = 0.02) areas; borderline ganglion cell layer thinning (p = 0.051) and outer nuclear layer (p = 0.03) thinning in the central retina and outer segment layer thinning nasally (p = 0.01) between the first and the second visit in macula. Correlation of the difference in optic disc and macular parameters with the age at enrolment did not reveal any significance. CONCLUSIONS: Statistically detectable thinning of the optic nerve and macula structures occurred already after 12 months. The proximity of optic nerve changes to the vascular arcades can possibly be explained by involvement of retinal vessels in the pathophysiology of ONHD.

Clinical features and imaging characteristics in achiasmia.

Achiasmia is a rare visual pathway maldevelopment with reduced decussation of the axons in the optic chiasm. Our aim was to investigate clinical characteristics, macular, optic nerve and brain morphology in achiasmia. A prospective, cross-sectional, observational study of 12 participants with achiasmia [8 males and 4 females; 29.6 ± 18.4 years (mean ± standard deviation)] and 24 gender-, age-, ethnicity- and refraction-matched healthy controls was done. Full ophthalmology assessment, eye movement recording, a high-resolution spectral-domain optical coherence tomography of the macular and optic disc, five-channel visual-evoked responses, eye movement recordings and MRI scans of the brain and orbits were acquired. Achiasmia was confirmed in all 12 clinical participants by visual-evoked responses. Visual acuity in this group was 0.63 ± 0.19 and 0.53 ± 0.19 for the right and left eyes, respectively; most participants had mild refractive errors. All participants with achiasmia had see-saw nystagmus and no measurable stereo vision. Strabismus and abnormal head position were noted in 58% of participants. Optical coherence tomography showed optic nerve hypoplasia with associated foveal hypoplasia in four participants. In the remaining achiasmia participants, macular changes with significantly thinner paracentral inner segment (P = 0.002), wider pit (P = 0.04) and visual flattening of the ellipsoid line were found. MRI demonstrated chiasmatic aplasia in 3/12 (25%), chiasmatic hypoplasia in 7/12 (58%) and a subjectively normal chiasm in 2/12 (17%). Septo-optic dysplasia and severe bilateral optic nerve hypoplasia were found in three patients with chiasmic aplasia/hypoplasia on MRI. In this largest series of achiasmia patients to date, we found for the first time that neuronal abnormalities occur already at the retinal level. Foveal changes, optic nerve hypoplasia and the midline brain anomaly suggest that these abnormalities could be part of the same spectrum, with different manifestations of events during foetal development occurring with varying severity.

Retinal Development in Infants and Young Children With Albinism: Evidence for Plasticity in Early Childhood.

MEETING PRESENTATION: Presented at the 2016 Association for Research in Vision and Ophthalmology meeting and at the 2015 British Isles Paediatric, Ophthalmology and Strabismus Association meeting. PURPOSE: To investigate the time course of foveal development after birth in infants with albinism. DESIGN: Prospective, comparative cohort optical coherence tomography study. METHODS: Thirty-six children with albinism were recruited. All participants were between 0 and 6 years of age and were seen at Leicester Royal Infirmary. A total of 181 mixed cross-sectional and longitudinal optical coherence tomography examinations were obtained, which were analyzed for differences in retinal development in comparison to 297 cross-sectional control examinations. RESULTS: Normal retinal development involves migration of the inner retinal layers (IRLs) away from the fovea, migration of the cone photoreceptors into the fovea, and elongation of the outer retinal layers (ORLs) over time. In contrast to controls where IRL migration from the fovea was almost completed at birth, a significant degree of IRL migration was taking place after birth in albinism, before arresting prematurely at 40 months postmenstrual age (PMA). This resulted in a significantly thicker central macular thickness in albinism (Δ = 83.8 ± 6.1, P < .0001 at 69 months PMA). There was evidence of ongoing foveal ORL elongation in albinism, although reduced in amplitude compared with control subjects after 21 months PMA (Δ = -17.3 ± 4.3, P < .0001). CONCLUSIONS: We have demonstrated evidence of ongoing retinal development in young children with albinism, albeit at a reduced rate and magnitude compared with control subjects. The presence of a period of retinal plasticity in early childhood raises the possibility that treatment modalities, which aim to improve retinal development, could potentially optimize visual function in albinism.

Abnormal Retinal Vessel Architecture in Albinism and Idiopathic Infantile Nystagmus.

Purpose: Infantile nystagmus syndrome (INS) causes altered visual development and can be associated with abnormal retinal structure, to which vascular development of the retina is closely related. Abnormal retinal vasculature has previously been noted in albinism but not idiopathic infantile nystagmus. We compared the number and diameter of retinal vessels in participants with albinism (PWA) and idiopathic infantile nystagmus (PWIIN) with controls. Methods: Fundus photography data from 24 PWA, 10 PWIIN, and 34 controls was analyzed using Automated Retinal Image Analyzer (ARIA) software on a field of analysis centered on the optic disc, the annulus of which extended between 4.2 mm and 8.4 mm in diameter. Results: Compared with controls, the mean number of arterial branches was reduced by 24% in PWA (15.5 vs. 20.3, P < 0.001), and venous branches were reduced in both PWA (29%; 12.9 vs. 18.2, P < 0.001) and PWIIN (17%; 15.1 vs. 18.2, P = 0.024). PWA demonstrated 7% thinner "primary" (before branching) arteries (mean diameter: 75.39 µm vs. 80.88 µm, P = 0.043), and 13% thicker (after branching) "secondary" veins (66.72 µm vs. 59.01 µm in controls, P = 0.009). Conclusions: PWA and PWIIN demonstrated reduced retinal vessel counts and arterial diameters compared with controls. These changes in the superficial retinal vascular network may be secondary to underdevelopment of the neuronal network, which guides vascular development and is also known to be disrupted in INS.

Detection and characterisation of optic nerve and retinal changes in primary congenital glaucoma using hand-held optical coherence tomography.

OBJECTIVE: To investigate (1) the feasibility of scanning the optic nerve (ON) and central retina with hand-held optical coherence tomography (HH-OCT) without sedation or anaesthesia in primary congenital glaucoma (PCG), (2) the characteristics of ON changes in comparison with adult primary open-angle glaucoma (POAG) in comparison with matched controls, (3) the sensitivity and specificity of ON parameters for diagnosis, and (4) changes of foveal morphology. METHODS AND ANALYSIS: HH-OCT (Envisu 2300; Leica Microsystems) was used to investigate ON and foveal morphology of 20 children with PCG (mean age 4.64±2.79) and 10 adult patients with POAG (mean age 66.8±6.94), and compared with age-matched, gender-matched and ethnicity-matched healthy controls without sedation or anaesthesia. RESULTS: HH-OCT yielded useful data in 20 out of 24 young children with PCG. Patients with PCG had significantly deeper cup changes than patients with POAG (vs respective age-matched controls, p=0.014). ON changes in PCG are characterised by significant increase in cup depth (165%), increased cup diameter (159%) and reduction in rim area (36.4%) as compared with controls with high sensitivity (81.5, 74.1% and 88.9%, respectively) and specificity (85.0, 80.0% and 75.0%, respectively). Patients with PCG have a significantly smaller width of the macula pit (p<0.001) with non-detectable external limiting membrane. CONCLUSION: HH-OCT has the potential to be a useful tool in glaucoma management for young children. We have demonstrated the use of HH-OCT in confirming a diagnosis of glaucoma within the studied cohort and found changes in disc morphology which characterise differently in PCG from POAG.

Assessment of the anterior segment of patients with primary congenital glaucoma using handheld optical coherence tomography.

PURPOSE: To investigate the potential of handheld optical coherence tomography (HH-OCT) in assessing the anterior segment of the eye in patients with primary congenital glaucoma. DESIGN: A prospective, case-controlled observational study. PARTICIPANTS: Twenty-two patients with primary congenital glaucoma (PCG, 9 females and 13 males; mean age 4.36 ± 3.4 years) and age-, gender- and ethnicity-matched healthy participants. METHODS: Anterior OCT was performed in all participants using a high-resolution HH SD-OCT device (Envisu 2300, Leica Microsystems, Germany) without anaesthesia or sedation. RESULTS: Anterior HH-OCT in PCG visualised Haab's striae in 14.3%, uneven internal cornea in 9.5% and epithelial thickening in 11.9% of patients with central corneal thickening (CCT, p < 0.001). CCT was significantly correlated with the intraocular pressure (IOP, p < 0.001). The flat iris with a thin collarette zone was found in 59.5%, anterior iris insertion in 11.90% of eyes affected by PCG. Two independent examiners showed sensitivity and specificity of 87% and 77%, respectively, by instating iris thinning and flattening of the anterior profile. CONCLUSIONS: Anterior HH-OCT has significant potential to improve diagnosis and management of PCG. Clinically relevant information can be obtained non-invasively and without sedation. High specificity makes anterior HH-OCT an important adjunct for management of PCG. Excellent visualisation of the iris insertion on OCT indicates potential for AS OCT to assist with surgical planning, including decision on the type of surgery and location of the incision.

Retinal and optic nerve changes in microcephaly: An optical coherence tomography study.

OBJECTIVE: To investigate the morphology of the retina and optic nerve (ON) in microcephaly. METHODS: This was a prospective case-control study including 27 patients with microcephaly and 27 healthy controls. All participants underwent ophthalmologic examination and handheld optical coherence tomography (OCT) of the macula and ON head. The thickness of individual retinal layers was quantified at the foveal center and the parafovea (1,000 µm nasal and temporal to the fovea). For the ON head, disc diameter, cup diameter, cup-to-disc ratio, cup depth, horizontal rim diameter, rim area, peripapillary retinal thickness, and retinal nerve fiber layer thickness were measured. RESULTS: Seventy-eight percent of patients had ophthalmologic abnormalities, mainly nystagmus (56%) and strabismus (52%). OCT abnormalities were found in 85% of patients. OCT revealed disruption of the ellipsoid zone, persistent inner retinal layers, and irregular foveal pits. Parafoveal retinal thickness was significantly reduced in patients with microcephaly compared to controls, nasally (307 ± 44 vs 342 ± 19 µm, p = 0.001) and temporally (279 ± 56 vs 325 ± 16 µm, p < 0.001). There was thinning of the ganglion cell layer and the inner segments of the photoreceptors in microcephaly. Total peripapillary retinal thickness was smaller in patients with microcephaly compared to controls for both temporal (275 vs 318 µm, p < 0.001) and nasal sides (239 vs 268 µm, p = 0.013). CONCLUSIONS: Retinal and ON anomalies in microcephaly likely reflect retinal cell reduction and lamination alteration due to impaired neurogenic mitosis. OCT allows diagnosis and quantification of retinal and ON changes in microcephaly even if they are not detected on ophthalmoscopy.

In Vivo Morphology of the Optic Nerve and Retina in Patients With Parkinson's Disease.

PURPOSE: To investigate optic nerve (ON) and macular morphology in patients with Parkinson's disease (PD) using spectral-domain optical coherence tomography (SD-OCT). SUBJECTS: Twenty-five participants with PD (19 males and 6 females; mean age 60.79; SD ± 9.24) and 25 sex-, age-, ethnicity-, and refraction-matched healthy controls. METHODS: A high-resolution SD-OCT device was used to acquire scans in 25 participants with PD (mean age 60.79; ± SD 9.24) and 25 sex-, age-, ethnicity-, and refraction-matched healthy controls. Main outcome measures included optic nerve head parameters (disc/cup diameters/areas, cup/rim volumes, cup depth, cup/disc ratio; peripapillary retinal nerve fiber layer [ppRNFL] thickness), retinal thickness (in inner and outer annuli around the foveal center) and thickness of individual retinal layers. RESULTS: Our study showed significant ppRNFL thinning in PD patients in all quadrants (P < 0.05) associated with a shallower optic cup (P = 0.03) as compared with controls. Foveal remodelling with retinal thinning (nasal and temporal segments in both annuli; and superior segment in outer annulus; P < 0.05), foveal pit widening (P = 0.05), central outer plexiform layer (OPL) thickening (P < 0.001), and nasal RPE thinning (P < 0.001) was also found in PD. The differences were more obvious in hemiretinae related to the predominantly affected cerebral hemisphere. Changes were more pronounced in advanced stages and longer PD duration. CONCLUSIONS: Optic nerve changes in PD are likely to be caused by primary neurodegeneration. Central retinal thinning, pit widening, central OPL thickening, and RPE thinning indicate foveal remodelling. Specific changes of the fovea and thinning of individual retinal layers, correlating with disease severity and duration, indicate that ON and retinal changes have potential to be used as biomarkers for PD.

Characterization of Abnormal Optic Nerve Head Morphology in Albinism Using Optical Coherence Tomography.

PURPOSE: To characterize abnormalities in three-dimensional optic nerve head (ONH) morphology in people with albinism (PWA) using spectral-domain optical coherence tomography (SD-OCT) and to determine whether ONH abnormalities relate to other retinal and clinical abnormalities. METHODS: Spectral-domain OCT was used to obtain three-dimensional images from 56 PWA and 60 age- and sex-matched control subjects. B-scans were corrected for nystagmus-associated motion artefacts. Disc, cup, and rim ONH dimensions and peripapillary retinal nerve fiber layer (ppRNFL) thickness were calculated using Copernicus and ImageJ software. RESULTS: Median disc areas were similar in PWA (median = 1.65 mm2) and controls (1.71 mm2, P = 0.128), although discs were significantly elongated horizontally in PWA (P < 0.001). In contrast, median optic cup area in PWA (0.088 mm2) was 23.7% of that in controls (0.373 mm2, P < 0.001), with 39.4% of eyes in PWA not demonstrating a measurable optic cup. This led to significantly smaller cup to disc ratios in PWA (P < 0.001). Median rim volume in PWA (0.273 mm3) was 136.6% of that in controls (0.200 mm3). The ppRNFL was significantly thinner in PWA compared with controls (P < 0.001), especially in the temporal quadrant. In PWA, ppRNFL thickness was correlated to ganglion cell thickness at the central fovea (P = 0.007). Several ONH abnormalities, such as cup to disc ratio, were related to higher refractive errors in PWA. CONCLUSIONS: In PWA, ocular maldevelopment is not just limited to the retina but also involves the ONH. Reduced ppRNFL thickness is consistent with previous reports of reduced ganglion cell numbers in PWA. The thicker rim volumes may be a result of incomplete maturation of the ONH.

In Vivo Foveal Development Using Optical Coherence Tomography.

PURPOSE: To characterize the time course of normal foveal development in vivo in term infants and young children using handheld spectral-domain optical coherence tomography (HH-SDOCT). METHODS: We obtained 534 HH-SDOCT scans from 261 infants, children, and young adults with a mean age of 4.9 years (range, 0-27 years). Each retinal layer was manually segmented in ImageJ and correlated with gestational age (GA) and visual acuity (VA). The developmental trajectories of each retinal layer at the fovea, parafovea, and perifovea were calculated using fractional polynomial modeling. RESULTS: The central macular thickness (CMT) increases logarithmically between birth and 48.6 months GA. The foveal ganglion cell (GCL), inner plexiform, inner nuclear (INL), and outer plexiform layers decrease in thickness exponentially until 18 months GA. Interestingly, the parafoveal and perifoveal GCL and INL thicknesses initially decrease until 17 months GA and then increase in thickness until 65.5 GA. The foveal outer nuclear layer, inner segment, and outer segment of the photoreceptors increase in thickness logarithmically until 32.4, 26.9, and 45.3 months GA, respectively. The parafoveal and perifoveal outer retinal layers increase in thickness more gradually until 146 months GA. The thickness of the outer retinal layers and CMT were strongly correlated with VA, with r = 0.54 (P < 0.0001) and r = 0.52 (P < 0.0001), respectively. CONCLUSIONS: We have modeled for the first time the complex, nonlinear developmental trajectories for each retinal layer and demonstrate that development continues until adolescence. Our description of normal development will be helpful in diagnosing, monitoring, and understanding pediatric retinal disease.

Normal macular structure measured with optical coherence tomography across ethnicity.

OBJECTIVE: The difference in prevalence of various retinal pathologies in people of different ethnicity is well established. Optical coherence tomography (OCT) is a widely used technique that allows quantitative analysis of macular structure. In this study, we investigated macular layer morphology in healthy subjects using high-resolution spectral domain (SD) OCT across ethnicities comparing Asian (ie, Indian subcontinent) and Caucasian individuals. METHODS: 133 healthy volunteers (67-Asian, 66-Caucasian) were examined using SD-OCT. Average retinal and nerve fibre layer thickness were measured in a semiautomated way. Analysis of the measurements of each retinal layer at the macula was quantified using tomograms obtained by SD-OCT. RESULTS: In this study, we find significant difference in macular structure in Asian and Caucasian participants. Caucasian subjects have thicker inner segment (p=0.015 in the central region), outer segment (p=0.04 in the temporal region) and outer nuclear (p=0.021 and p=0.03 for the central and temporal regions, respectively) layers, while Asians demonstrate thicker retinal pigment epithelial layer (p=0.004 for the temporal region). CONCLUSIONS: Differences in macular morphology due to ethnicity should be considered in determining control values for diagnostic purposes, and can be used to guide future studies in risk and prognosis for macular pathologies.

Morphology of retinal vessels in patients with optic nerve head drusen and optic disc edema.

PURPOSE: We quantitatively investigated the peripapillary vascular morphology in patients with optic nerve head drusen (ONHD) and optic disc edema (ODE). METHODS: Computer-based fundus analysis was used to investigate peripapillary vascular morphology, including length, branching, and diameter of arteries and veins calibrated by optical coherence tomography. RESULTS: Patients with ONHD showed significantly larger diameters of arteries without branching (P = 0.05), and arteries after primary/before secondary branching (P = 0.04) and secondary venous branching started closer to the optic disc (P = 0.03) compared to healthy controls. The ODE patients had significantly reduced number of small peripapillary veins and larger number of veins without branching compared to ONHD and controls (P = 0.02). Anomalous branching with arterial and venous trifurcation presented in the ODE and ONHD groups, with significant higher prevalence in ODE patients for venous trifurcations compared to ONHD and controls (P = 0.02). CONCLUSIONS: The diameter of vessels in ONHD patients were significantly larger in arteries without branching (P = 0.05), after primary branching (P = 0.04), and venous branching closer to the disc area (P = 0.03) compared to controls. The ODE patients demonstrated widening of the small peripapillary veins measured by a significantly larger number of veins without branching (P = 0.001 and P = 0.02, compared to controls and ONHD, respectively) and less small veins (P = 0.001 and P = 0.04, compared to controls and ONHD, respectively).