An Evidence-Based Approach to Abnormal Vision in the Emergency Department

Table of Contents

 

Nontraumatic visual disorders can have many causes, but they are potentially concerning for the patient as well as the emergency clinician. Four divisions can assist in considering the differential diagnosis: (1) unilateral or bilateral; (2) painful or painless; (3) presence or absence of diplopia; and (4) timing of onset.

What are the red flags to watch out for?

What are the essential components of the eye exam and visual exam? What are the important diagnoses that might be missed if it’s not complete?

What does anisocoria indicate, and what will the swinging flashlight test tell you about the pathology?

When is ultrasound useful, and when is CT preferred?

What is the latest evidence on managing central retinal artery occlusion: anticoagulation therapy, systemic thrombolysis, or intra-arterial thrombolysis?

If optic neuritis is diagnosed, what does this portend for a diagnosis of multiple sclerosis?

Is there any reliable way to tell whether a patient is suffering from functional blindness?

How does sickle cell disease affect the eyesight of patients?

What are the important eye complaints that may arise in HIV patients?

1. Abstract
2. Case Presentations
3. Introduction
4. Critical Appraisal of the Literature
5. Anatomy, Etiology, and Pathophysiology
   1. Disorders of the Ocular Media
      1. Corneal Abnormalities
      2. Hyphema, Hypopyon, and Iritis
      3. Glaucoma
   2. Disorders of the Lens
   3. Retinal and Vitreal Disorders
      1. Retinal and Vitreal Detachments
      2. Retinal Vein Occlusion
      3. Retinal Artery Occlusion and Ischemia
      4. Retinal Migraine
   4. Disorders of the Optic Nerve
      1. Optic Neuritis
      2. Anterior Ischemic Optic Neuropathy
      3. Posterior Ischemic Optic Neuropathy
      4. Idiopathic Intracranial Hypertension
      5. Neuro-Ophthalmologic and Other Retrobulbar Etiologies of Abnormal Vision
         • Diplopia
         • Cranial Nerve Palsies
   5. Cavernous Sinus Thrombosis
   6. Pharmacologic, Toxicologic, and Metabolic Etiologies of Abnormal Vision
6. Differential Diagnosis
7. Prehospital Care
8. Emergency Department Evaluation
   1. History
      1. Red Flags
      2. Past Medical History and Specific Risk Factors
   2. Physical Examination
      1. Visual Acuity
      2. Visual Fields
      3. Exterior Eye and Facial Examination
      4. Extraocular Movements
      5. The Pupil
      6. Anterior Eye Segment
      7. The Posterior Eye
      8. Measuring Intraocular Pressure
9. Diagnostic Studies
   1. Laboratory Studies
   2. Lumbar Puncture
   3. Imaging Studies
      1. Computed Tomography
      2. Ultrasound
      3. Magnetic Resonance Imaging
10. Treatment
    1. Unilateral Eye Conditions
       1. Floaters/ Retinal Detachment
       2. Amaurosis Fugax
       3. Central Retinal Artery Occlusion
       4. Central Retinal Vein Occlusion
       5. Arteritis
       6. Anterior Ischemic Optic Neuropathy
       7. Posterior Ischemic Optic Neuropathy
       8. Abnormal Pupil
       9. Acute Angle-Closure Glaucoma
       10. Optic Neuritis and Demyelinating Disease
    2. Bilateral Painless Vision Loss
       1. Idiopathic Intracranial Hypertension
       2. Psychogenic Blindness
       3. Bilateral Field Cuts
    3. Cavernous Sinus Thrombosis
    4. Diplopia
       1. Binocular Diplopia
11. Special Populations
    1. Patients With Sickle Cell Disease
    2. Patients With HIV
    3. Patients With Ventricular Shunts
12. Cutting Edge
13. Disposition
14. Summary
15. Time and Cost-Effective Strategies
16. Risk Management Pitfalls for Patients With Abnormal Vision in the Emergency Department
17. Case Conclusions
18. Clinical Pathways
    1. Clinical Pathway for Managing Patients With Acute Visual Change
    2. Clinical Pathway for Managing Patients With Bilateral Visual Change
    3. Clinical Pathway for Managing Patients With Unilateral Painful Visual Change
    4. Clinical Pathway for Managing Patients With Diplopia
19. Tables and Figures
    1. Table 1. Nonarteritic Anterior Ischemic Optic Neuropathy-Associated Diseases and Causes
    2. Table 2. Causes of Monocular Diplopia
    3. Table 3. Causes of Toxic Optic Neuropathy
    4. Table 4. Differential Diagnosis of Abnormal Vision
    5. Table 5. Diagnoses That May Be Missed With an Incomplete Eye Examination
    6. Table 6. Uses of Point-of-Care Ultrasound in Eye Conditions
    7. Table 7. Causes of Anisocoria
    8. Table 8. Emergency Department Treatment of Acute Angle-Closure Glaucoma
    9. Table 9. Medical Treatment of Idiopathic Intracranial Hypertension
    10. Table 10. Signs of Functional Blindness
    11. Table 11. Causes of Field Cuts
    12. Table 12. Causes of Binocular Diplopia
    13. Table 13. Ocular Infections Associated With HIV Infection
    14. Figure 1. Eye Anatomy
    15. Figure 2. Hyphema
    16. Figure 3. Hypopyon
    17. Figure 4. Central Retinal Vein Occlusion
    18. Figure 5. Retinal Artery Occlusion
    19. Figure 6. Anterior Ischemic Optic Neuropathy
    20. Figure 7. Anatomy of the Cavernous Sinus
    21. Figure 8. Visual Field Defects Correlate to Location of Pathology Along the Optic Pathway
    22. Figure 9. Swinging Flashlight Test
    23. Figure 10. Ultrasound Image of Retinal Detachment-Hyperechoic Membrane Attached to the Retina
    24. Figure 11. Ultrasound Image of Vitreous Hemorrhage-Hyperechoic Echoes in the Vitreous
    25. Figure 12. Ultrasound Image of Papilledema With Optic Nerve Measurement Made at 3-mm Depth
    26. Figure 13. Pupillary Involvement in Cranial Nerve III Palsy
20. References

Abstract

Patients present to the ED with visual disturbances that may be painful or painless and may include loss of visual acuity, field cuts, diplopia, and headache. A detailed history and complete ocular examination are essential to obtaining the correct diagnosis and offering expedited treatment and referral. This review discusses the differential diagnosis for patients experiencing abnormal vision from a nontraumatic or minimally traumatic etiology, and reviews diagnostic and treatment strategies from an evidence-based perspective, including point-of-care ocular ultrasound. Management of the needs of special populations, such as patients with sickle cell disease, HIV, and those with a ventriculoperitoneal shunt, is reviewed.

Case Presentations

A 40-year-old woman is brought in to the ED by her husband, complaining of blurred vision and dizziness. She said she had visited an urgent care clinic last week with a new diagnosis of migraine headache. Her examination is remarkable for right eyelid ptosis, limited movement of the right eye to left gaze, and a right dilated pupil compared to the left. Her husband comments that his brother “had the same thing with his diabetes,” and asks you to check her sugar, but you think something else might be going on...

A nurse interrupts and tells you there is another patient in the room next door who has suddenly lost sight in both eyes, and the nurse wants to know whether she should call a stroke alert. You excuse yourself and step out to see a 21-year-old woman who is hyperventilating and screaming, “I can’t see! I can’t see!” You ponder the cause of her symptoms, and you note that her medications include alprazolam and sertraline. You wonder what the best way to confirm your suspected diagnosis would be...

Before you can respond, another nurse interjects and asks for pain medicine for the man in room 4 who has a red, painful eye that developed overnight. Your first suspicion is that it's a simple case of conjunctivitis, but the patient has intense pain when light is shined in the opposite eye. You wonder what else could be going on...

Introduction

The presentation of a patient with a change in vision is common in the emergency department (ED), and potential diagnoses range from the minimally significant, to vision-threatening, or even life-threatening. Clinician experience, availability of equipment and technology, and time may all impact the care of these patients. This issue of Emergency Medicine Practice focuses on a symptom-based approach to the management of a variety of nontraumatic ocular conditions. Advances in emergency ocular ultrasound techniques and other technological advances can promote diagnostic certainty, help emergency clinicians communicate with consultants, and improve outcomes. For a review on managing traumatic eye conditions in the ED, see the November 2015 issue of Emergency Medicine Practice, “Ocular Injuries: New Strategies in Emergency Department Management”.

Critical Appraisal of the Literature

A literature search was conducted using Ovid MEDLINE^®, requesting English language articles published since 2014 involving humans, and excluding case reports. A total of 271 full-text review articles were found. An additional search was performed using the Cochrane Database of Systematic Reviews and Database of Abstracts of Reviews of Effects (DARE). Further PubMed searches were carried out for primary studies on specific topics. Specialty guidelines were also searched and reviewed.

Overall, there is a lack of high-quality evidence for most of the therapies that are typically used in the ED for ocular complaints; specific treatment and diagnostic modalities with strong supportive evidence are highlighted. Pertinent guidelines from the American Academy of Ophthalmology are included. There are no clinical practice guidelines available from the American College of Emergency Physicians or the American Academy of Emergency Medicine for the care of ocular emergencies.

Anatomy, Etiology, and Pathophysiology

A review of the basic anatomy of the eye and the visual pathway is helpful in understanding visual pathology. (See Figure 1.) Light enters via the cornea, exits the anterior chamber through the pupil and refracts off the lens, traversing the vitreous humor to the retina. Photoreceptors generate signals; rods for dim-light vision and cones for color- and bright-light vision. The macula, in the center of the retina, contains the fovea, where there is the highest concentration of cones, making it responsible for the most precise vision. The visual signals exit along the optic nerve and travel to the optic chiasm, where the impulses decussate; ie, information from one side of the visual field is interpreted by the opposite side of the brain. The signals continue from the optic chiasm to the lateral geniculate bodies, and on to the occipital lobe via the optic radiations. Included in the pathway is the Edinger-Westphal nuclei, from which the extraocular movements of the eye, accommodation, pupillary dilatation, and convergence are affected.

Disorders of the Ocular Media

The ocular media encompass the transparent substances such as the cornea, aqueous humor, lens, and vitreous humor. As a group, these parts of the eye permit refraction and image transmission to the retina. Inflammation or deposition of cells or protein will obscure vision.

Corneal Abnormalities

Pathology of the cornea presents with pain, redness, tearing, and a foreign-body sensation. Corneal pain will typically resolve with a topical anesthetic, while pain from more serious causes (glaucoma, intraocular foreign body, etc) will not. Corneal pathology may arise from a variety of causes, including infection, minor trauma, autoimmune disease, foreign body, and exposures (both chemical and ultraviolet).

Risk Management Pitfalls for Patients With Abnormal Vision in the Emergency Department

2. “She had a headache and said her vision was off, but I checked her pressures and they were OK. She said she was better with the pain medicine, so I discharged her.”

Consider temporal arteritis in patients who are aged > 50 years with headache and visual complaints. Order an ESR and CRP in these patients. Visual loss can be rapid and sudden, so a timely diagnosis is essential.

3. “He said he saw those floaters all the time! His vision was fine.”

Always consider retinal detachment with a complaint of flashing lights or increased visual floaters. Remember that visual acuity is preserved when the macula is spared. Check for field cuts and perform a fundoscopic examination. Consider ocular ultrasound to find retinal detachment.

7. “He said he had blurred vision, but he wasn’t very specific about it, and I didn’t think much of it. I can’t believe he had a brain mass!”

Make sure you translate the patient’s words into an accurate medical diagnosis. Just as “dizzy” can mean anything from vertigo to orthostasis, “blurred vision” can signify diplopia, decreased visual acuity, a field cut, and more.

Tables and Figures

References

Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.

To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study is included in bold type following the references, where available. In addition, the most informative references cited in this paper, as determined by the author, are highlighted.

1. Giuseffi V, Wall M, Siegel PZ, et al. Symptoms and disease associations in idiopathic intracranial hypertension (pseudotumor cerebri): a case-control study. Neurology. 1991;41(2Pt 1):239-244. (Case control study; 50 patients, 100 controls)
2. Hoffmann J, Mollan SP, Paemeleire K, et al. European Headache Federation guideline on idiopathic intracranial hypertension. J Headache Pain. 2018;19(1):93. (European consensus guidelines after analysis of randomized controlled trials and systematic reviews)
3. Best J, Silvestri G, Burton B, et al. The incidence of blindness due to idiopathic intracranial hypertension in the UK. The Open Ophthalmology Journal. 2013;7:26-29. (Prospective study; 19 cases)
4. Sharma P, Sharma R. Toxic optic neuropathy. Indian J Ophthalmol. 2011;59(2):137-141. (Overview of causes)
5. Chan FLY, Lester S, Whittle SL, et al. The utility of ESR, CRP and platelets in the diagnosis of GCA. BMC Rheumatology. 2019;3:14-14. (Case note review; 270 patients)
6. Kermani TA, Schmidt J, Crowson CS, et al. Utility of erythrocyte sedimentation rate and C-reactive protein for the diagnosis of giant cell arteritis. Semin Arthritis Rheum. 2012;41(6):866-871. (Retrospective review; 764 patients)
7. Gottlieb M, Holladay D, Peksa GD. Point-of-care ocular ultrasound for the diagnosis of retinal detachment: a systematic review and meta-analysis. Acad Emerg Med. 2019;26(8):931-939. (Meta-analysis; 11 studies, 844 patients)
8. Mollan SP, Davies B, Silver NC, et al. Idiopathic intracranial hypertension: consensus guidelines on management. J Neurol Neurosurg Psychiatry. 2018;89(10):1088-1100. (Review and meta-analysis)
9. Witmer MT, Cohen SM. Oral anticoagulation and the risk of vitreous hemorrhage and retinal tears in eyes with acute posterior vitreous detachment. Retina. 2013;33(3):621-626. (Retrospective review; 331 patients)
10. Mueller AJ, Neubauer AS, Schaller U, et al. Evaluation of minimally invasive therapies and rationale for a prospective randomized trial to evaluate selective intra-arterial lysis for clinically complete central retinal artery occlusion. Arch Ophthalmol. 2003;121(10):1377-1381. (Retrospective noncomparative case series; 71 patient records)
11. Rudkin AK, Lee AW, Aldrich E, et al. Clinical characteristics and outcome of current standard management of central retinal artery occlusion. Clin Exp Ophthalmol. 2010;38(5):496-501. (Retrospective analysis; 2 cohorts in 2 hospitals)
12. Fiess A, Cal O, Kehrein S, et al. Anterior chamber paracentesis after central retinal artery occlusion: a tenable therapy? BMC Ophthalmol. 2014;14:28. (Retrospective data analysis; 74 patients)
13. Youn TS, Lavin P, Patrylo M, et al. Current treatment of central retinal artery occlusion: a national survey. J Neurol. 2018;265(2):330-335. (Survey of hospitals; 45 institutions)
14. Olsen TW, Pulido JS, Folk JC, et al. Retinal and ophthalmic artery occlusions Preferred Practice Pattern(® Ophthalmology. 2017;124(2):P120-P143. (American Academy of Ophthalmology clinical guideline)
15. Biousse V, Nahab F, Newman NJ. Management of acute retinal ischemia: Follow the guidelines! Ophthalmology. 2018;125(10):1597-1607. (Review article)
16. Powers WJ, Rabinstein AA, Ackerson T, et al. 2018 guidelines for the early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2018;49(3):e46-e110. (Expert consensus)
17. Sharma RA, Dattilo M, Newman NJ, et al. Treatment of nonarteritic acute central retinal artery occlusion. Asia Pac J Ophthalmol (Phila). 2018;7(4):235-241. (Review article and summary of treatment options)
18. Chronopoulos A, Schutz JS. Central retinal artery occlusion-a new, provisional treatment approach. Surv Ophthalmol. 2019;64(4):443-451. (Review article)
19. Schrag M, Youn T, Schindler J, et al. Intravenous fibrinolytic therapy in central retinal artery occlusion: a patient-level meta-analysis. JAMA Neurol. 2015;72(10):1148-1154. (Patient-level meta-analysis; 7 studies, 396 patients)
20. Wolf A, Schumacher M, Neubauer AS, et al. [Comparison of superselective intraarterial fibrinolysis with conservative therapy. Use in patients with acute non-arteritic central retinal artery occlusion]. Ophthalmologe. 2010;107(9):799-805. (Randomized trial; 84 patients)
21. Schumacher M, Schmidt D, Jurklies B, et al. Central retinal artery occlusion: local intra-arterial fibrinolysis versus conservative treatment, a multicenter randomized trial. Ophthalmology. 2010;117(7):1367-1375. (Prospective multicenter randomized trial; 9 centers, 84 patients)
22. Page PS, Khattar NK, White AC, et al. Intra-arterial thrombolysis for acute central retinal artery occlusion: a systematic review and meta-analysis. Front Neurol. 2018;9:76. (Meta-analysis; 5 retrospective controlled studies, 1 randomized clinical trial)
23. Mehta N, Marco RD, Goldhardt R, et al. Central retinal artery occlusion: acute management and treatment. Curr Ophthalmol Rep. 2017;5(2):149-159. (Comprehensive review and analysis)
24. Pulido JS, Flaxel CJ, Adelman RA, et al. Retinal vein occlusions Preferred Practice Pattern(®) guidelines. Ophthalmology. 2016;123(1):P182-P208. (American Academy of Ophthalmology clinical guideline)
25. Yeh S, Kim SJ, Ho AC, et al. Therapies for macular edema associated with central retinal vein occlusion: a report by the American Academy of Ophthalmology. Ophthalmology. 2015;122(4):769-778. (American Academy of Ophthalmology clinical guideline)
26. Brown DM, Campochiaro PA, Singh RP, et al. Ranibizumab for macular edema following central retinal vein occlusion: six-month primary end point results of a phase III study. Ophthalmology. 2010;117(6):1124-1133. (Prospective, randomized, sham injection-controlled, double-masked, multicenter clinical trial)
27. Gao L, Zhou L, Tian C, et al. Intravitreal dexamethasone implants versus intravitreal anti-VEGF treatment in treating patients with retinal vein occlusion: a meta-analysis. BMC Ophthalmol. 2019;19(1):8. (Meta-analysis; 4 randomized controlled trials, 969 eyes)
28. Lazo-Langner A, Hawel J, Ageno W, et al. Low molecular weight heparin for the treatment of retinal vein occlusion: a systematic review and meta-analysis of randomized trials. Haematologica. 2010;95(9):1587-1593. (Meta-analysis of randomized trials; 229 patients)
29. Buttgereit F, Dejaco C, Matteson EL, et al. Polymyalgia rheumatica and giant cell arteritis: a systematic review. JAMA. 2016;315(22):2442-2458. (Systematic review; 20 clinical trials, 1016 patients)
30. Stone JH, Tuckwell K, Dimonaco S, et al. Trial of tocilizumab in giant-cell arteritis. N Engl J Med. 2017;377(4):317-328. (Phase 3 comparative study, multicenter randomized controlled trial)
31. Moster ML, Sergott RC, Leiby BE. Dalfampridine treatment in nonarteritic anterior ischemic optic neuropathy. J Neuroophthalmol. 2017;37(3):348-349. (Clinical trial; 20 patients)
32. Enriquez-Marulanda A, Salem MM, Ascanio LC, et al. No differences in effectiveness and safety between pipeline embolization device and stent-assisted coiling for the treatment of communicating segment internal carotid artery aneurysms. Neuroradiol J. 2019:1971400919845368. (Retrospective review; 38 aneurysms)
33. Salahuddin H, Siddiqui N, Castonguay AC, et al. Recent trends in electively treated unruptured intracranial aneurysms. J Stroke Cerebrovasc Dis. 2019. (Data analysis of 31,000 cases)
34. Pagiola I, Mihalea C, Caroff J, et al. Flow diversion treatment of aneurysms of the complex region of the anterior communicating artery: which stent placement strategy should ‘I’ use? A single center experience. J Neurointerv Surg. 2019;11(11):1118-1122. (Retrospective review; 30 patients)
35. Martinez-Perez R, Rayo N, Montivero A, et al. The “brain stress timing” phenomenon and other misinterpretations of randomized clinical trial on aneurysmal subarachnoid hemorrhage. Neural Regen Res. 2019;14(8):1364-1366. (Meta-analysis; 4 randomized clinical trials comparing methods of surgical treatment)
36. Markus HS, Levi C, King A, et al. Antiplatelet therapy vs anticoagulation therapy in cervical artery dissection: the Cervical Artery Dissection in Stroke Study (CADISS) randomized clinical trial final results. 2019;76(6):657-664. JAMA Neurol. (Randomized prospective multicenter trial; 250 patients)
37. Lam DS, Chua JK, Tham CC, et al. Efficacy and safety of immediate anterior chamber paracentesis in the treatment of acute primary angle-closure glaucoma: a pilot study. Ophthalmology. 2002;109(1):64-70. (Prospective noncomparative case series; 8 patients)
38. Cioboata M, Anghelie A, Chiotan C, et al. Benefits of anterior chamber paracentesis in the management of glaucomatous emergencies. J Med Life. 2014;7 Spec No. 2:5-6. (Observational study; 24 patients)
39. Gal RL, Vedula SS, Beck R. Corticosteroids for treating optic neuritis. Cochrane Database Syst Rev. 2015 Aug 14(8):CD001430. (Cochrane review; 6 randomized controlled trials, 750 participants)
40. Comi G, Filippi M, Barkhof F, et al. Effect of early interferon treatment on conversion to definite multiple sclerosis: a randomised study. Lancet. 2001;357(9268):1576-1582. (Randomized placebo study; 241 patients)
41. Wolinsky JS. Glatiramer acetate for the treatment of multiple sclerosis. Expert Opin Pharmacother. 2004;5(4):875-891. (Review article)
42. Button J, Al-Louzi O, Lang A, et al. Disease-modifying therapies modulate retinal atrophy in multiple sclerosis: a retrospective study. Neurology. 2017;88(6):525-532. (Retrospective review; 402 patients)
43. Thurtell MJ, Wall M. Idiopathic intracranial hypertension (pseudotumor cerebri): recognition, treatment, and ongoing management. Curr Treat Options Neurol. 2013;15(1):1-12. (Review article)
44. Yiangou A, Mitchell J, Markey KA, et al. Therapeutic lumbar puncture for headache in idiopathic intracranial hypertension: minimal gain, is it worth the pain? Cephalalgia. 2019;39(2):245-253. (Prospective trial; 52 patients)
45. van der Poel NA, Mourits MP, de Win MML, et al. Prognosis of septic cavernous sinus thrombosis remarkably improved: a case series of 12 patients and literature review. Eur Arch Otorhinolaryngol. 2018;275(9):2387-2395. (Case series and review of the literature)
46. Ferro JM, Bousser MG, Canhao P, et al. European Stroke Organization guideline for the diagnosis and treatment of cerebral venous thrombosis - endorsed by the European Academy of Neurology. Eur J Neurol. 2017;24(10):1203-1213. (Consensus expert guidelines for treatment in cerebral venous thrombosis)
47. Viegas LD, Stolz E, Canhao P, et al. Systemic thrombolysis for cerebral venous and dural sinus thrombosis: a systematic review. Cerebrovasc Dis. 2014;37(1):43-50. (Systematic review of treatment in 50 cases; no randomized trial included)
48. Sussman J, Farrugia ME, Maddison P, et al. Myasthenia gravis: Association of British Neurologists’ management guidelines. Pract Neurol. 2015;15(3):199-206. (Practice guidelines)
49. Gharaibeh A, Savage HI, Scherer RW, et al. Medical interventions for traumatic hyphema. Cochrane Database Syst Rev. 2019 Jan 14;1:CD005431. (Cochrane review; 20 randomized trials, 2643 patients)
50. Abdalla Elsayed MEA, Mura M, Al Dhibi H, et al. Sickle cell retinopathy. A focused review. Graefes Arch Clin Exp Ophthalmol. 2019;257(7):1353-1264. (Nonsystematic focused literature review)
51. Myint KT1 SS, Thein AW, Moe S, Ni H. Laser therapy for retinopathy in sickle cell disease. Cochrane Database Syst Rev. 2015 Oct 9;(10):CD010790. (Cochrane review; 2 trials, 341 eyes; data 20 years old)
52. Biousse V, Bruce BB, Newman NJ. Ophthalmoscopy in the 21st century: the 2017 H. Houston Merritt Lecture. Neurology. 2018;90(4):167-175. (Lecture)
53. Petrushkin H, Barsam A, Mavrakakis M, et al. Optic disc assessment in the emergency department: a comparative study between the PanOptic and direct ophthalmoscopes. Emerg Med J. 2012;29(12):1007-1008. (Single-masked prospective observational study)
54. Panwar N, Huang P, Lee J, et al. Fundus photography in the 21st century--a review of recent technological advances and their implications for worldwide healthcare. Telemed J E Health. 2016;22(3):198-208. (Review)
55. Bruce BB, Bidot S, Hage R, et al. Fundus photography vs. ophthalmoscopy outcomes in the emergency department (FOTO-ED) phase III: web-based, in-service training of emergency providers. Neuroophthalmology. 2018;42(5):269-274. (Web-based training; 587 patients)
56. Bruce BB, Thulasi P, Fraser CL, et al. Diagnostic accuracy and use of nonmydriatic ocular fundus photography by emergency physicians: phase II of the FOTO-ED study. Ann Emerg Med. 2013;62(1):28-33 e21. (Fundus photograph review; 239 patients)