Optic Disc Drusen Research Articles

Peripapillary hyperreflective ovoid mass-like structures: multimodal imaging and associated diseases.

Growing evidence has demonstrated that peripapillary hyperreflective ovoid mass-like structures (PHOMS) are novel structures rather than a subtype of optic disc drusen. They correspond to the laterally bulging herniation of optic nerve fibers and are believed to be the marker of axoplasmic stasis. PHOMS present in a broad spectrum of diseases, including optic disc drusen, tilted disc syndrome, papilloedema, multiple sclerosis, non-arteritic anterior ischemic optic neuropathy, optic neuritis, Leber hereditary optic neuropathy, and so on. We focus on the multimodal imaging features, pathophysiological mechanisms of PHOMS, and their association with multiple diseases and healthy people in this review to deepen the ophthalmologists' understanding of PHOMS. Additionally, we provide some new directions for future research.

Clinical and morpho-functional results of a second examination of a patient with optic nerve head drusen taken after a long-time interval (27 years)

Optic disc drusen (ODD) is a bilateral anomaly of the optic nerve, in which hyaline calcified intercellular inclusions appear in the optic disc head area in front of the cribriform plate. As a rule, in the early stages, ODD patients have no complaints, central vision does not suffer, while perimetry data may show an expansion of the blind spot and narrowed visual field. As complications are developing and the optic nerve atrophy is progressing, visual acuity may decrease. The visual functions are deteriorating gradually. In the clinical case discussed, a patient with optic disc drusen was examined for a second time after a prolonged interval (27 years).The ophthalmoscopic picture and functional parameters obtained during this examination clearly confirmed the unfavorable course of optic disc drusen and the need for such patents to be regularly examined for changes in visual functions (visual field), the state of the retina and the optic nerve.

Retinal Nerve Fiber Layer as The Preferred Objective Measure in Differentiating Pseudopapilledema with True Papilledema: A Systematic Review

Abstract
 Introduction & Objectives : Distinguishing pseudopapilledema from true papilledema may generate confusion for some cases. Regardless of the subjective judgment on clinical examination alone, objective measurement for confirmation of diagnosis might be costly, operator-dependent, invasive, or not readily available. This study aims to evaluate whether retinal nerve fiber layer (RNFL) could be the reliable and efficient objective measure to ascertain the diagnosis.
 Methods : Literatures were obtained by comprehensive searching on PubMed, ProQuest, Google Scholar, and Cochrane between 2012 - 2023. Last search was March 26, 2023. Non-english study, animal study, review articles, case studies, and editorial letters were excluded. We included studies with available full-text containing both groups of papilledema and pseudopapilledema. The result was presented according to Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guideline.
 Results : A total of 615 participants were included from 8 different studies all comprising a group of papilledema and pseudopapilledema with or without optic disc drusen (ODD). Studies resulted in good accuracy on RNFL in differentiating pseudopapilledema with papilledema as the area under curve ranging from 0,78 to 0,91. However, specificity and sensitivity were varied between 65-100% and 33-91% respectively. Lower accuracy was found when pseudopapilledema only includes patients with ODD or papilledema was narrowed to mild papilledema.
 Conclusion : RNFL is a useful objective measure with favorable accuracy in differentiating pseudopapilledema with papilledema especially in acute settings or whenever operator-dependent examination is not obtainable

Prevalence of common and rare ophthalmic findings in adults attending a medical survey institute

PurposeTo examine the ophthalmic data from a large database of people attending a general medical survey institute, and to investigate ophthalmic findings of the eye and its adnexa, including differences in age and sex.MethodsRetrospective analysis including medical data of all consecutive individuals whose ophthalmic data and the prevalences of ocular pathologies were extracted from a very large database of subjects examined at a single general medical survey institute.ResultsData were derived from 184,589 visits of 3676 patients (mean age 52 years, 68% males). The prevalence of the following eye pathologies were extracted. Eyelids: blepharitis (n = 4885, 13.3%), dermatochalasis (n = 4666, 12.7%), ptosis (n = 677, 1.8%), ectropion (n = 73, 0.2%), and xanthelasma (n = 160, 0.4%). Anterior segment: pinguecula (n = 3368, 9.2%), pterygium (n = 852, 2.3%), and cataract or pseudophakia (n = 9381, 27.1%). Cataract type (percentage of all phakic patients): nuclear sclerosis (n = 8908, 24.2%), posterior subcapsular (n = 846, 2.3%), and capsular anterior (n = 781, 2.1%). Pseudophakia was recorded for 697 patients (4.6%), and posterior subcapsular opacification for 229 (0.6%) patients. Optic nerve head (ONH): peripapillary atrophy (n = 4947, 13.5%), tilted disc (n = 3344, 9.1%), temporal slope (n = 410, 1.1%), ONH notch (n = 61, 0.2%), myelinated nerve fiber layer (n = 94, 0.3%), ONH drusen (n = 37, 0.1%), optic pit (n = 3, 0.0%), and ON coloboma (n = 4, 0.0%). Most pathologies were more common in males except for ONH, and most pathologies demonstrated a higher prevalence with increasing age.ConclusionsNormal ophthalmic data and the prevalences of ocular pathologies were extracted from a very large database of subjects seen at a single medical survey institute.

Retro-mode imaging for the diagnosis of optic disc drusen: a case series

ObjectiveWe aimed to compare the detectability of optic disc drusen (ODD), using various non-invasive imaging techniques, including the novel retro-mode imaging (RMI), as well as to analyze the morphological characteristics of ODD on RMI. MethodsThis study involved seven patients with bilateral ODD, totaling 14 eyes. Multimodal imaging techniques, including multicolor fundus photography (MC), near-infrared reflectance (NIR), green and blue light fundus autofluorescence (G-FAF and B-FAF, respectively), and RMI were used to examine the eyes. FAF was used as the primary method of identifying ODD, and each method's detection rate was compared by two observers. Quantitative measurements of ODD included the number of ODD visualized by the RMI technique, the perimeter (P) and area (A) of ODD were identified. ResultsThe average age of the patients included was 49.28 ± 23.16 years, with five of the seven being men. RMI was able to detect ODD in all cases, with a sensitivity of 100%, compared to MC (sensitivity 60.71%), NIR (sensitivity 60.71%), B-FAF (sensitivity 100%), G-FAF (sensitivity 100%). RMI was the only imaging technique capable of assessing ODD morphology and quantifying ODD. ConclusionsRMI is a promising imaging modality for diagnosing superficial ODD, providing valuable information on the distribution, location, and size of ODD. We suggest the incorporation of RMI as a complementary tool for diagnosing and monitoring ODD in combination with other multimodal imaging methods.

Pediatric orbital lesions: ocular pathologies.

Orbital pathologies can be broadly classified as ocular, extra-ocular soft-tissue (non-neoplastic and neoplastic), osseous, and traumatic. In part 1 of this orbital series, the authors will discuss the differential diagnosis and key imaging features of pediatric ocular pathologies. These include congenital and developmental lesions (microphthalmos, anophthalmos, persistent fetal vasculature, coloboma, morning glory disc anomaly, retinopathy of prematurity, Coats disease), optic disc drusen, infective and inflammatory lesions (uveitis, toxocariasis, toxoplasmosis), and ocular neoplasms (retinoblastoma, retinal hamartoma, choroidal melanoma, choroidal nevus). This pictorial review provides a practical approach to the imaging work-up of these anomalies with a focus on ocular US as the first imaging modality and additional use of CT and/or MRI for the evaluation of intracranial abnormalities. The characteristic imaging features of the non-neoplastic mimics of retinoblastoma, such as persistent fetal vasculature and Coats disease, are also highlighted.

Advantages and Pitfalls of the Use of Optical Coherence Tomography for Papilledema.

Papilledema refers to optic disc swelling caused by raised intracranial pressure. This syndrome arises from numerous potential causes, which may pose varying degrees of threat to patients. Manifestations of papilledema range from mild to severe, and early diagnosis is important to prevent vision loss and other deleterious outcomes.The purpose of this review is to highlight the role of optical coherence tomography (OCT) in the diagnosis and management of syndromes of raised intracranial pressure associated with papilledema. Ophthalmoscopy is an unreliable skill for many clinicians. Optical coherence tomography is a non-invasive ocular imaging technique which may fill a current care gap, by facilitating detection of papilledema for those who cannot perform a detailed fundus examination.Optical coherence tomography may help confirm the presence of papilledema, by detecting subclinical peripapillary retinal nerve fiber layer (pRNFL) thickening that might otherwise be missed with ophthalmoscopy. Enhanced depth imaging (EDI) and swept source OCT techniques may identify optic disc drusen as cause of pseudo-papilledema. Macular ganglion cell inner plexiform layer (mGCIPL) values may provide early signs of neuroaxonal injury in patients with papilledema and inform management for patients with syndromes of raised intracranial pressure. There are well-established advantages and disadvantages of OCT that need to be fully understood to best utilize this method for the detection of papilledema.Overall, OCT may complement other existing tools by facilitating detection of papilledema and tracking response to therapies. Moving forward, OCT findings may be included in deep learning models to diagnose papilledema.

Concomitant optic disk drusen and papilledema due to idiopathic intracranial hypertension in a pediatric cohort

BackgroundOptic disk drusen (ODD) in pediatric patients typically presents with pseudopapilledema. Diagnosing concomitant papilledema due to idiopathic intracranial hypertension (IIH) in these patients can be challenging. The purpose of this study was to evaluate the incidence and clinical features of papilledema due to IIH among pediatric patients with a new diagnosis of ODD and to discuss the clinical and paraclinical findings that helped diagnose this group. MethodsThe medical records of children <15 years of age with ODD confirmed by B-scan ultrasound at their first visit over a 4-year period (2019-2022) were reviewed retrospectively. Patients with concurrent IIH were identified, and the demographic and clinical characteristics were reviewed. ResultsA total of 83 children with confirmed ODD at the initial presentation were included, of whom 4 (4.8%) were diagnosed with concomitant IIH. Patients ranged in age from 7 to 15 years; 3 of the 4 were female, and 3 had IIH-related symptoms at presentation (1 was asymptomatic). None of the 4 patients had papilledema greater than Frisen grade 2. ConclusionsWe recommend that clinicians review pertinent IIH symptoms and risk factors in children with ODD and follow the standard workup for IIH in suspicious cases. In asymptomatic patients with a new diagnosis of ODD, we recommend obtaining a follow-up optic nerve evaluation and optical coherence tomography scan to detect any significant interval change that might serve as a possible indicator of concomitant papilledema.

Application of Optical Coherence Tomography Angiography in True and Pseudo-Optic Disc Swelling.

We evaluated the optic disc microvasculature in healthy subjects and patients with optic nerve head drusen (ONHD), active papilledema, and acute nonarteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography angiography (OCTA). This prospective, comparative case series included sixteen eyes with ONHD, thirty-one eyes with active papilledema, sixteen eyes with acute NAION, and thirty-two healthy eyes. The Optovue AngioVue OCT and OCTA Imaging System recorded peripapillary retinal nerve fiber layer (RNFL) thickness and vessel density maps from the radial peripapillary capillary (RPC) slab. Average RNFL thicknesses were greater in eyes with ONHD, papilledema, and NAION compared to control eyes (all Ps < 0.001), but this parameter did not differ among patient groups. The mean peripapillary vessel density did not differ between the ONHD and control groups (P=1.000), nor between the NAION and papilledema groups (P=0.216). However, this value in the ONHD and control groups was significantly higher than in the NAION and papilledema groups (all Ps < 0.05). RPC density is influenced during the progression of conditions such as ONHD, papilledema, and NAION. Although a decrease in vessel density values has been observed in cases of true disc edema, further research is necessary to assess the potential of OCTA in differentiating between true and pseudo-optic disc edema.

Visual Field Defects in Patients With Optic Nerve Head Drusen.

Background Optic nerve head drusen (ONHD) are acellular deposits in the optic nerve head, whose pathophysiology remains not fully understood. Most patients with ONHD have visual field (VF) defects. This study aims to describe the VF defects observed in patients with ONHD and to compare the anatomical and functional impairment between visible and buried ONHD. Methods Patients with ONHD were retrospectively studied. The retinal nerve fiber layer (RNFL) average thickness and the ganglion cell complex (GCC) average thickness were collected from optical coherence tomography data. Visual field index (VFI), mean deviation (MD), and pattern standard deviation (PSD) were collected from 30-2 standard automated perimetry. An abnormal VF test was defined as having a Glaucoma Hemifield Test outside normal limits and/or a PSD with a p-value<5%. Eyes with superficial or buried ONHD based on visibility by slit-lamp ophthalmoscopy were compared. Results Sixty-six eyes of 36 patients were included in the study. The mean age was 39.6 ± 2.5 years. Forty-nine eyes (81.7%) presented a VF defect: concentric VF constriction in 19 (38.8%), arcuate scotoma in 16 (32.7%), enlarged blind spot in 9 (18.4%), unspecific VF defect in 8 (16.3%), and nasal step in 3 (6.1%). Thirty-four eyes (51.5%) had superficial ONHD and 32 eyes (48.5%) had buried ONHD. Patients with superficial ONHD were significantly older (p<0.001) and presented a significantly lower VFI (p=0.010), lower MD (p=0.002), higher PSD (p<0.001), thinner GCC (p<0.001), and thinner RNFL (p<0.001) than patients with buried ONHD. VF defects were present in 90.6% of eyes with superficial ONHD and 71.4% of eyes with buried ONHD (p=0.113). The type of VF defects differed between groups (p=0.020). Conclusions Functional and structural impairment is more evident in eyes with superficial ONHD, maybe because the presence of calcification leads to greater axonal damage. Buried ONHD is more prevalent in younger patients, progressing to a superficial location and becoming calcified with age.

Optic Disc Drusen Prevalence in Patients With Retinitis Pigmentosa: A Cross-Sectional Study.

Studies of patients with retinitis pigmentosa (RP) have reported an increased prevalence of optic disc drusen (ODD) compared with the ODD prevalence in the general population. The diagnostic gold standard method for identifying ODD is enhanced depth imaging optical coherence tomography (EDI-OCT), but this modality has not previously been used systematically for identifying ODD in patients with RP. This study aimed to estimate the prevalence of ODD in patients with RP using EDI-OCT. In this cross-sectional study, 40 patients with clinically diagnosed RP aged 18 years or older were included. All patients underwent an ophthalmic examination, including kinetic perimetry, EDI-OCT of the optic nerve head, and fundus photography. Genetic testing with a next-generation sequencing panel of retinal dystrophy genes was performed on the RP patients without a prior genetic diagnosis. Twelve patients (30.0%) had at least one ODD. Six patients had bilateral ODD. No significant differences between patients with and without ODD were found according to age, refraction, best-corrected visual acuity, Bruch membrane opening, or visual field. The genetic variation causing RP was found in 11 of 12 cases in the ODD group and in 17 of 28 cases in the group without ODD. We found the prevalence of ODD in patients with RP to be 30.0%. This is 15 times higher than in the general population and much higher than previously estimated in most studies, potentially indicating that the 2 conditions might be pathogenically related.

Understanding pseudopapilledema on spectral domain optical coherence tomography.

Optic nerve head drusen (ONHD), peripapillary hyperreflective ovoid mass-like structures (PHOMS), and horizontal hyperreflective lines (HHL) are commonly seen in eyes with pseudopapilledema on enhanced depth imaging (EDI) spectral domain optical coherence tomography (SDOCT). The objective of this study is to assess the frequency of ONHD, PHOMS, and HHL on spectral domain OCT in the eyes diagnosed to have pseudopapilledema. A retrospective case-control study included patients diagnosed as pseudopapilledema and had EDI SD OCT imaging of the optic nerve head (n = 48 eyes) and controls (n = 20 eyes). OCT scans through the optic nerve head were studied to diagnose ONHD, HHL, and PHOMS. One proportion z test was used to find the difference in proportions. Forty eight eyes of 27 subjects were studied. ONHD as described by the optic disc drusen Studies consortium was noted in 19 eyes (39.48%), P value-0.032, PHOMS in 31 eyes (64.6%), P value 0.043, HL in 19 eyes (39.48%), P value 0.032, and none of the normals had ONHD, PHOMS, and HHL. PHOMS are more frequently seen than ONHD and HHL in eyes with pseudopapilledema.

Clinical Findings and Optical Coherence Tomography Measurements of Pediatric Patients with Papilledema and Pseudopapilledema.

To compare the clinical findings and multimodal imaging of pediatric patients diagnosed with papilledema and pseudopapilledema with those of healthy individuals. Ninety children (<18 years of age) referred for suspected papilledema were included in this study. All patients underwent optical coherence tomography (OCT) imaging and were compared with normal control subjects. Fifty-eight children diagnosed with pseudopapilledema, 32 children with mild-to-moderate papilledema, and 40 controls were evaluated. The average and all quadrants of retinal nerve fiber layer (RNFL) thickness were significantly higher in the papilledema group than in the pseudopapilledema and control groups (p<0.001). Bruch's membrane opening (BMO) measurements were similar in both groups (p>0.05). The average, nasal, and temporal RNFL thicknesses were significantly higher in the pseudopapilledema group compared with the controls (p<0.001). Area under the receiver operating characteristic (ROC) curve showed high diagnostic ability for RNFL thickness in all quadrants to differentiate papilledema from pseudopapilledema (p<0.001). In the pseudopapilledema group, average, temporal, and inferior RNFL thickness and BMO measurements were significantly higher in eyes with optic nerve head drusen (n=28) compared with those without drusen (n=88) (p=0.035, p=0.022, p=0.040 and, p=0.047 respectively). Papilledema and pseudopapilledema show great differences in evaluation, follow-up, and prognosis. Using non-invasive methods such as newly developed OCT techniques in differential diagnosis can relieve patients with pseudopapilledema from the stress and financial burden of expensive, extensive, and invasive procedures.

Decision Factors for Glaucoma Suspects and Ocular Hypertensive Treatment at an Academic Center.

Practice guidelines assert that high-risk glaucoma suspects should be treated. Yet, there is ambiguity regarding what constitutes a high enough risk for treatment. The purpose of this study was to determine which factors contribute to the decision to treat glaucoma suspects and ocular hypertensive patients in an academic ophthalmology practice. Retrospective cohort study of glaucoma suspects or ocular hypertensives at an academic ophthalmology practice from 2014 to 2020. Demographics, comorbidities, intraocular pressure (IOP), optical coherence tomography (OCT) findings, and visual field measurements were compared between treated and untreated patients. A multivariable logistic regression model assessed predictors of glaucoma suspected treatment. Of the 388 patients included, 311 (80%) were untreated, and 77 (20%) were treated. There was no statistical difference in age, race/ethnicity, family history of glaucoma, central corneal thickness (CCT), or any visual field parameters between the two groups. Treated glaucoma suspects had higher IOP, thinner retinal nerve fiber layers (RNFL), more RNFL asymmetry, thinner ganglion cell-inner plexiform layers (GCIPL), and a higher prevalence of optic disc drusen, disc hemorrhage, ocular trauma, and proliferative diabetic retinopathy (PDR) (p < 0.05 for all). In the multivariable model, elevated IOP {odds ratio [OR] 1.16 [95% confidence interval (CI) 1.04-1.30], p = 0.008}, yellow temporal [5.76 (1.80-18.40), p = 0.003] and superior [3.18 (1.01-10.0), p = 0.05] RNFL quadrants, and a history of optic disc drusen [8.77 (1.96-39.34), p = 0.005] were significant predictors of glaucoma suspect treatment. Higher IOP, RNFL thinning, and optic disc drusen were the strongest factors in the decision to treat a glaucoma suspect or ocular hypertensive patient. RNFL asymmetry, GCIPL thinning, and ocular comorbidities may also factor into treatment decisions. Understanding the clinical characteristics that prompt glaucoma suspect treatment helps further define glaucoma suspect disease status and inform when treatment should be initiated. Ciociola EC, Anderson A, Jiang H, et al. Decision Factors for Glaucoma Suspects and Ocular Hypertensive Treatment at an Academic Center. J Curr Glaucoma Pract 2023;17(3):157-165.

Optic disc drusen and scleral canal size - protocol for a systematic review and meta-analysis.

Around one in forty patients are diagnosed with optic disc drusen (ODD) during their lifetime. Complications of these acellular deposits range from asymptomatic visual field deficits to artery occlusion and subsequent cecity. Still, the pathogenesis of their emergence remains controversial. In particular, it was suggested 50 years ago that a narrow disc and scleral canal is one factor leading to axoplasmic flow disturbance, which induces ODD formation. However, this hypothesis is still debated today. To evaluate the basis of this theory, we will conduct a systematic review and meta-analysis of studies evaluating the scleral canal size in patients with ODD and in healthy subjects. We will search MEDLINE via PubMed, Cochrane, and EMBASE electronic databases to identify articles published before November 29, 2022 that measure the scleral canal size in patients with ODD and in healthy subjects. In addition, grey literature will be searched. The meta-analysis will include studies that include patients with a clinical or imaging diagnosis of ODD and healthy subjects. Additionally, we will perform a subgroup analysis to compare patients with buried ODD and patients with visible ODD. Extracted data from included studies will be presented descriptively, and effect sizes will be computed based on the recommendations from the Cochrane Collaboration handbook. The hypothesis that a narrow scleral canal is a risk factor of ODD has long been debated and this systematic review and meta-analysis should disentangle the different views. Understanding the underlying factors driving the development of ODD should help us focus on patients at risk and develop strategies to prevent advanced stages of the disease in these patients. Besides, focusing on patients with small scleral canals should help us derive associated factors and provide a better understanding of the pathology. https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022375110.

Multimodal imaging of optic disc drusen with peripapillary choroidal neovascularization

Multimodal imaging of optic disc drusen with peripapillary choroidal neovascularization

A unique case of bilateral nanophthalmos and pigmentary retinal abnormality with unilateral angle closure glaucoma and optic disc pit

BackgroundMicroophthalmos or ‘dwarf eye’ is characterized by an axial length 2 standard deviation less than age-matched controls. It is classified into nanophthalmos, relative anterior microphthalmos, and posterior microphthalmos based on the anterior segment: posterior segment ratio. Nanophthalmos can occur in association with optic disc drusen, foveoschisis, and retinitis pigmentosa, as an autosomal recessive syndrome linked to mutations in the MFRP gene. We report a case of bilateral nanophthalmos and pigmentary retinopathy with angle closure glaucoma and optic disc pit in one eye. We believe this to be the first case presenting with optic disc pit in association with nanophthalmos.Case presentationA 56-year-old female presented with bilateral small eyes, high hypermetropia, shallow anterior chamber depth, increased lens thickness, mid-peripheral retinal flecks, and macular edema. She also had high intraocular pressure in the right eye, with a disc cupping of 0.9 with an Optic disc pit. The macular edema in the right eye was found to occur in association with the Optic disc pit, whereas, in the left eye, it was associated with intra-retinal hemorrhages and diagnosed as macular branch retinal vein occlusion secondary to hypertension. She was started on anti-glaucoma medications in both eyes and planned for Anti-VEGF injection in the left eye.ConclusionThis case report is unique as it reports an association of Nanophthalmos with Optic Disc pit, with an associated angle closure glaucoma in the same eye, an association which has never been previously reported in the literature.

Artificial Intelligence-Based ChatGPT Responses for Patient Questions on Optic Disc Drusen.

Optic disc drusen (ODD) are acellular deposits in the optic nerve head, which are most often benign and asymptomatic. Patients may develop visual field defects and be at increased risk of ischemic co-morbidities. As ODD can be difficult to distinguish from papilledema, patients are at risk of unnecessary clinical workups. Patient information is a key aspect of ODD management. In this study, we explored the accuracy of ChatGPT responses for typical patient questions on ODD. Two content experts reached consensus on 20 typical patient questions. We retrieved five separate responses for each question from ChatGPT, totaling 100 responses. Each response was evaluated on a 5-point Likert-scale on accuracy by each content expert in an individual fashion. The two experts were in fair/substantial agreement in the evaluation of responses (Cronbach's alpha: 0.64). Of the 100 responses, 17 were relevant and without any inaccuracies, 78 were relevant and with inaccuracies not being harmful, and five were relevant and with inaccuracies potentially harmful. The lowest accuracy scores were obtained for questions dealing with treatment and prognosis. ChatGPT often provides relevant answers for patient questions on ODD, but inaccuracies become potentially harmful when questions deal with treatment and prognosis.

Computed tomographic finding of bilateral optic nerve head drusen in a dog – a case report

Optic nerve head drusen are acellular calcified deposits in the optic nerve head reported in humans. A six year old, male, Rottweiler dog with a history of respiratory distress and epistaxis for the previous two months was anaesthetised and a computed tomographic scan of the head was performed. The axial view of the computed tomography scan with a slice thickness of 1mm was viewed in a soft tissue window (380x40 HU). There was an incidental discovery of a characteristic discrete round hyper dense area in the optic nerve head region in both eyes during the routine computed tomographic scan. The Hounsfield Unit of the optic nerve head drusen in the right eye measured 91 HU, of 2 mm2 and in the left eye 131 HU of 1 mm2 confirming the diagnosis of optic nerve head drusen. To the authors’ knowledge, this is the first report of optic nerve head drusen in a dog.

Reply to Schimmelbusch, K.J.; Collison, F.T. Comment on "Rosa et al. Optic Nerve Drusen Evaluation: A Comparison between Ultrasound and OCT. J. Clin. Med. 2022, 11, 3715".

We appreciate the comments of Schimmelbusch et al. [...].