Moran CORE

Open source ophthalmology education for students, residents, fellows, healthcare workers, and clinicians. Produced by the Moran Eye Center in partnership with the Eccles Library

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Retinal Detachment

Medical Student Education Outline / Retina

Title: Retinal Detachment

Author: Brian Besch, 4th Year Medical Student, University of Utah School of Medicine

Introduction: Retinal detachment (RD) is the separation of the neurosensory retina from the underlying retinal pigment epithelium (RPE) and choroid.  Retinal photoreceptors are transducers which convert photons into electoral impulses, subsequently delivered by optic neural tracts to the visual cortex.  The retina is one of the most metabolically active tissues in the body, and heavily reliant on support of the underlying RPE and choroid to provide oxygen, nutrients, and metabolic waste removal to maintain function.  Physical separation of these layers results in retinal ischemia; when sustained, photoreceptor atrophy leads to decreased vision.

Pathophysiology: Broadly, RD is categorized into three major etiologies: rhegmatogenous, traction, and exudative.  Rhegmatogenous RD, the most common type, develops from a full-thickness retinal tear; the defect allows adjacent vitreous fluid to leak under the tear, dissecting the layers.  This typically stems from posterior vitreous detachment (PVD), a physiological normal part of aging in which the gel-like vitreous degrades to a more liquid consistency.  Pockets of developing fluid within the vitreous alter its shape, causing an overall inward collapse, placing tension on the vitreoretinal interface that may lead to tears.  PVD generally manifests between age 50-75, and increased risk of tears are observed in myopic patients, or those with a history of ocular trauma or inflammation.  In the latter two cases, excessive fibrosis and tissue remodeling strengthens vitreoretinal adhesions, increasing propensity for tears during detachment.  Traction RD is similar to rhegmatogenous RD, as mechanical traction forces create undue tension; however, no overt retinal tears or holes trigger detachment.  Traction RD is most commonly associated with retinal pathology involving neovascularization – a few examples include proliferative diabetic retinopathy, retinopathy of prematurity, or vitreomacular adhesions.  Ischemia induces new blood vessel growth, but the vasculature is disorganized, weak, and prone to leakage and fibrosis.  Exudative RD results when fluid accumulates between the retina and RPE in the absence of a tear or hole.  Fluid collection can be associated with central serous chorioretinopathy, macular edema, neoplasms, or other inflammatory conditions which increase vascular permeability.  Additionally, RD may occur as a combination of these pathologies.

Signs & Symptoms: Patients with RD present with variable complaints of vision change depending on the underlying etiology and anatomical location of the tear.  The most common associated scenario, PVD, typically presents with the sudden onset of new floaters – translucent rope-like or cobweb-type structures which slowly move across the visual field, often more prominent with eye movement.  Flashes of light (photopsias) lasting a couple seconds may occur in the peripheral vision; these result from mechanical traction on photoreceptors causing depolarization and neural firing.  Larger, superior RDs may draw the retina anterior/inferior giving the patient the perception of a veil or curtain descending from the upper visual fields.  Release of pigment from underlying RPE can present as a shower or dark specks.  Tears may be accompanied by damage to small vessels, causing vitreous hemorrhage; depending on severity, this may present suddenly as small regions of blurring or distortion, to severe vision compromise with acuity reduced to finger-counting or light perception.  Less acute etiologies may present more insidiously, with slowly progressive changes preceding detachment – difficulty reading fine print, or field distortions or cuts.

Diagnosis & Management: Patients exhibiting aforementioned symptoms should be referred to an ophthalmologist for further evaluation within 24 hours, including slit-lamp biomicroscopy to examine the fundus, indirect ophthalmoscopy to assess the peripheral retina, and possibly optical coherence tomography (OCT) scanning.  The latter is non-invasive, high-resolution imaging of the retinal fundus in cross-sections to assess for macular involvement.  Patients with cornea or lens pathology obscuring adequate retina visualization can be assessed using ultrasound B-scan.  While these techniques are highly specialized to ophthalmology, the primary care practitioner can perform simple, brief, and inexpensive screening tests to guide referral.  These include assessing visual acuity and confrontation fields, and direct ophthalmoscopy.  Having the patient view an Amsler grid to identify blind spots, linear distortions, or other abnormalities is a quick test for retinal pathology.  Detailed discussion of RD treatment is beyond the scope of this article.  However, patients with PVD but no RD require careful monitoring and should be educated about alarm symptoms which may warrant reevaluation.  Those with retinal holes or tears are at elevated risk of developing RD, and may be treated with laser retinopexy or cryoretinopexy.  RDs themselves may be managed with scleral buckling, vitrectomy, retinal tamponade with gas bubble or silicone oil, or some combination of therapies depending on the specific scenario.  RDs associated with neovascularization or subretinal exudates due to inflammation will additionally benefit from interventions targeting the respective underlying pathology.

References:

Bowling, Brad. Kanski’s Clinical Ophthalmology: A Systemic Approach. Elsevier Limited. 2016

Hikichi T, Trempe CL, Schepens CL. Posterior vitreous detachment as a risk factor for retinal detachment. Ophthalmology 1995; 102:527.

D’Amico DJ. Clinical practice. Primary retinal detachment. N Engl J Med 2008; 359:2346.

 Wolfensberger TJ, Tufail A. Systemic disorders associated with detachment of the neurosensory retina and retinal pigment epithelium. Curr Opin Ophthalmol 2000; 11:455.

Hollands H, Johnson D, Brox AC, et al. Acute-onset floaters and flashes: is this patient at risk for retinal detachment? JAMA 2009; 302:2243.

Identifier: Moran_CORE_23968


Retinoblastoma

Home / Basic Ophthalmology Review / Vitreous

Title: Retinoblastoma

Author:  Spencer Fuller, MSIV – UC San Diego School of Medicine, MPH

Definition: Retinoblastoma (Rb) is an intraocular tumor occurring most commonly during childhood from spontaneous or familial mutations in chromosome 13.  It is the most common pediatric ocular tumor (1 in 15,000 live births) and can be either unilateral or bilateral.

Presentation: Rb most commonly presents as leukocoria, or an asymmetric, “white”, dimmed, or otherwise abnormal red reflex, often noticed by parents or caregivers.  The white pupillary reflex comes up in photos or can be caught by a clinician on routine direct ophthalmoscopy. Strabismus is also a common presenting sign, and one reason every child needs a dilated eye exam who develops strabismus.

The typical patient with Rb from a spontaneous mutation presents at 24 months of age with a unilateral tumor.  On the other hand, the typical patient with familial Rb from germline mutations presents at 12 months or even younger and is more likely to have bilateral involvement.  They are also at a significantly increased risk of secondary malignancies such as sarcomas (especially osteosarcomas of long bones) and pinealoblastoma [1]. Historically, patients with bilateral Rb and a pinealoblastoma are said to have developed “trilateral retinoblastoma.”

Differential Diagnosis (of leukocoria):

The differential diagnosis of leukocoria in children is broad and includes numerous hereditary, developmental, inflammatory, and miscellaneous conditions as well as benign and malignant non-Rb tumors [2]. These include, but are not limited to:

Diagnosis: Diagnosis is challenging and unique for intraocular tumors because biopsy and histopathologic diagnosis is not available due to the high risk of seeding the tumor outside of the eye.  Thus, the workup includes using several imaging and diagnostic modalities, many of which are done under anesthesia, such as:

  1. Slit lamp biomicroscopy and indirect ophthalmoscopy
  2. Retinal fundus photography
  3. Fluorescein Angiography – Rb is highly vascularized and its arteries fill early in the vascular filling phase
  4. Orbital/Head imaging to narrow the differential diagnosis and to assess for tumor size, calcification, concurrent retinal detachment, and other intracranial tumors associated with Rb (i.e. pinealoblastoma):
    1. B-scan ultrasonography
    2. MRI head and orbits (with high-resolution techniques such as surface coil, gadolinium enhancement, and fat suppression when available. [3])
    3. CT scanning is avoiding due to the risk radiation exposure, especially to patients who might have a germline Rb mutation.
  5. Conclusive diagnosis requires pathologic diagnosis and can be obtained via fine-needle aspiration (FNA). However, FNA is contraindicated in most if not all cases due to risk of “seeding” tumor cells via needle trauma. As a result, a conclusive diagnosis is often not made and choice of treatment is usually based on imaging results.
  6. Genetic testing for the Rb mutation can also provide information regarding whether the tumor is of germline origin and thus clarifies risk for bilateral involvement, secondary tumors at time of presentation, and future malignancies. Patients with the germline mutation require serial eye exams for surveillance of future tumors and well as lifelong serial MRI’s for secondary tumors.

Management: Rb spontaneously regresses in about 5% of cases. The other 95% of cases may require:

  1. Systemic chemoreduction – used to shrink tumor prior to other treatment modalities in an attempt to avoid retinal detachments, extensive vision loss or surgical removal of the globe (enucleation). Chemotherapy is typically reserved for bilateral cases.
  2. Intra-arterial and intra-vitreal chemotherapy – newer therapies that minimize systemic exposure to chemotherapeutic agents and often can salvage a globe. Intra-vitreal chemotherapy is particularly useful for tumors with vitreous seeding.  The advent of these techniques have dramatically decreased the number of enucleations.
  3. Transpupillary Thermotherapy, Laser Photocoagulation, or Cryotherapy – direct damage to the tumor and destroys the tumor’s blood supply.
  4. Plaque radiotherapy – a radioactive plaque that is sutured to the surface of the tumor to provide targeted, localized radiation therapy while sparing the remainder of the retina
  5. External beam radiation therapy – more of a historic treatment than a current one.
  6. Enucleation – reserved for large, unilateral cases. Avoided if possible, but often necessary.

Complications:

 

IMAGE(S) and/or VIDEO(S):

This patient with leukocoria eventually was diagnosed with Retinoblastoma and underwent enucleation.

An external photograph of Retinoblastoma taken as part of an exam under anesthesia (EUA).

An ultrasound B-scan demonstrating a retinal mass with characteristic calcifications, providing evidence that the tumor is a Retinoblastoma.

 

Jordan, Michael (2014). 2 year Old with Leukocoria. Moran Eye Center Grand Rounds http://morancore.utah.edu/section-06-pediatric-ophthalmology-and-strabismus/case-2-year-old-with-leukocoria/

REFRENCES:

  1. Shields, J. A., Shields, C. L. (2008). Retinoblastoma: Introduction, Genetics, Clinical Features, Classification. In Intraocular Tumors: An Atlas and Textbook (pp. 293-318). Lippincott Williams & Wilkins, Philadelphia, PA.
  2. Stagg, B., Ambati, BK. et al. (2014) Diagnostic Ophthalmology. Amirsys Publishing, Inc., Manitoba, Canada.
  3. Shields, J. A., Shields, C. L. (2008). Retinoblastoma: Diagnostic Approaches. In Intraocular Tumors: An Atlas and Textbook (pp. 319-326). Lippincott Williams & Wilkins, Philadelphia, PA.
  4. Shields, J. A., Shields, C. L. (2008). Retinoblastoma: Management of Retinoblastoma. In Intraocular Tumors: An Atlas and Textbook (pp. 327-332). Lippincott Williams & Wilkins, Philadelphia, PA.
  5. Shields, J. A., Shields, C. L. (2008). Lesions That Can Simulate Retinoblastoma. In Intraocular Tumors: An Atlas and Textbook (pp. 353-366). Lippincott Williams & Wilkins, Philadelphia, PA.
  6. Kamihara, J., Bourdeaut, F., Foulkes, W. D., Molenaar, J. J., Mossé, Y. P., Nakagawara, A., … & Walsh, M. F. (2017). Retinoblastoma and Neuroblastoma Predisposition and Surveillance. Clinical Cancer Research, 23(13), e98-e106.
  7. Lohmann DR, Gallie BL. Retinoblastoma. 2000 Jul 18 [Updated 2015 Nov 19]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1452/

Identifier: Moran_CORE_23958


Relative Afferent Pupillary Defect (RAPD)

Home / Basic Ophthalmology Review / Pupillary Exam

Title: Relative Afferent Pupillary Defect (RAPD)

Author: Marshall Huang, 4th Year Medical Student, University of Pittsburgh

A Relative Afferent Pupillary Defect is an examination finding in patients who have an asymmetric pupillary reaction to light when it is shined back and forth between the two eyes.  It is most commonly a sign of asymmetric optic nerve disease or damage but can also present in widespread asymmetric retinal disease.  The disease or condition causing the RAPD has to be asymmetric because if both eyes are equally affected than the pupillary reaction is symmetric.  This exam finding is best assessed with the swinging light test:

  1. In a dim room, have the patient fixate on a distant point
  2. Shine a light in one eye and allow pupil diameter to stabilize, shining the light directly into their eye for about 3 seconds
    1. Both pupils should constrict equally
  3. Quickly swing the light to the other eye and observe pupil diameter
    1. If that eye is normal, both pupils will constrict slightly
    2. If RAPD is present in that eye, both pupils will dilate
  4. Quickly swing the light back to the first eye
    1. If that eye is normal, both pupils will constrict slightly
    2. If RAPD is present in that eye, both pupils will dilate
  5. Repeat these steps several times to confirm your findings – be careful not to overexpose one eye and induce an RAPD.  Spend about 3 seconds on each eye and then switch to the other eye so that the light exposure remains equal between the two eyes.

Working up a positive RAPD:

Although an RAPD is almost always a result of an asymmetrical defect of the optic nerve or retina, any pathology that decreases the amount of light sensed by one eye relative to the other will result in this finding. Because of its potential urgency, it is important to determine the etiology of the RAPD. The first step is to take a careful history that focuses on the timing of visual changes, prior eye diseases, eye pain and any recent trauma.

If visual loss is present (which is almost always the case with an RAPD), the speed of onset is an important clue. A hyperacute onset of seconds to minutes points to a traumatic or vascular cause such as a fracture compressing the optic nerve, a large retinal detachment or ischemic optic neuropathy from something like a central retinal artery occlusion. In these cases, an urgent ophthalmic consultation is warranted because immediate intervention may preserve vision. An acute onset of visual loss of hours to days points to inflammation or infection of the optic nerve, such as optic neuritis. A subacute onset of days to months has a larger differential such as asymmetric glaucoma, severe macular degeneration or a mass in the orbit compressing on the optic nerve.

An RAPD is almost always correlated with some visual loss, however some patients with optic neuritis may retain 20/20 vision. This typically presents acutely with pain with eye movements and in a young patient, often female.

In summary, patients presenting with eye pain or unilateral vision loss need a careful pupillary exam, looking for an RAPD.  If present, this typically localizes to the optic nerve, though widespread retinal diseases are also a possibility.  Accompanied pain suggests an optic neuritis while painless vision loss with an RAPD are concerning for ischemic optic neuropathies.  In a young patient without any recent trauma, a mass or tumor compressing on the optic nerve is amongst the most concerning causes of painless vision loss with an RAPD.  In the elderly, this same presentation could be Giant Cell Arteritis, which if not caught and treated carries a high risk of having a stroke or causing vision loss in the other eye by the same mechanism.

See Also in the CORE:

How to Measure the Relative Afferent Pupillary Defect (RAPD)

Measuring the Relative Afferent Pupillary Defect (RAPD)

Central Retinal Artery Occlusion

Identifier: Moran_CORE_23955


Hypertensive Retinopathy

Home / Basic Ophthalmology Review / Retina

Title:  Hypertensive Retinopathy

Author:  J. Erik Kulenkamp, MS4, University of Chicago

Hypertension is a systemic disease characterized by elevated blood pressure, or blood pressure greater than 140/90 mmHg, and is seen in 73 million US adults.  Broadly, there exist two categories of hypertension:  essential and secondary.  Essential or primary hypertension is far more common in the general population and is not caused by another illness.  Secondary hypertension is a manifestation of another medical condition such as renal artery stenosis, obstructive sleep apnea, preeclampsia/eclampsia, Cushing’s syndrome, pheochromocytoma, coarctation of the aorta, and many others.  Regardless of etiology, acutely or chronically elevated blood pressures can damage the eye, and in particular, the retina.

Hypertensive retinopathy is the result of changes to the retinal vasculature in high blood pressure states.  Initially, arteriolar tone is increased due to autoregulation in the body’s attempt to reduce blood flow, causing the arterioles to narrow.  Over time, involved vessels can become sclerotic, with thickened intima and media layers.  Eventually, the blood-retina barrier can be disrupted, resulting in exudates and retinal ischemia or hemorrhage.

The signs and symptoms of hypertensive retinopathy vary depending on whether the elevation in blood pressure is chronic or acute.  Patients with chronic hypertension are often asymptomatic but can experience decreased vision.  Signs include arteriolar narrowing (with decreased size relative to corresponding venules), arteriovenous (AV) nicking (where arterioles cross venules), arteriolar sclerosis (with the appearance of copper wiring), flame hemorrhages, and cotton wool spots.  Many of these findings are visible in Figure 1.  Patients with acute or malignant hypertension can present with decreased vision and headaches, accompanied by significantly elevated blood pressure.  However, they can also be asymptomatic.  On fundoscopic exam, flame and dot blot hemorrhages, hard exudates, cotton wool spots, retinal edema, and papilledema (present in severe hypertensive retinopathy) can be seen.  Hypertensive retinopathy sometimes leads to retinal vein occlusions.  Less often, it precipitates serous retinal detachments or vitreous hemorrhages.

Diabetic retinopathy can present with similar findings and should be on the differential, especially in a patient with known diabetes.  However, it usually lacks classic signs of AV nicking and arteriolar narrowing.  Retinal vein occlusions can share overlapping features as well, although they’re more often unilateral.  If hypertensive retinopathy is suspected, review of systems should evaluate for symptoms of cardiovascular complications and other end-organ damage.  Providers should check blood pressure and auscultate for bruits.  In addition, they should either perform or refer for dilated fundoscopic examination (emergently if signs and symptoms of a hypertensive crisis are present).  Malignant hypertension should be managed acutely in the emergency department.  The treatment for hypertensive retinopathy involves controlling blood pressure through the administration of antihypertensive agents such as diuretics, angiotensin converting enzyme (ACE) inhibitors, Angiotensin II receptor blockers (ARB’s), calcium channel blockers, vasodilators, and alpha-adrenergic blockers.

Figure 1:  Classic findings in Hypertensive Retinopathy

Color Fundus Photo of Right Eye, Taken 5/29/2015 at JMEC
Pertinent History and Physical:  40 year old male presenting with blurry vision of several weeks duration and severely elevated blood pressure on exam.  After fundoscopy, he was transferred from clinic to the emergency department.Figure 2:  Hypertensive Retinopathy in Same Patient After Antihypertensive Treatment

Color Fundus Photo of Right Eye, Taken 8/31/15 at JMEC
Pertinent History and Physical:  40 year old male featured in Figure 1 with resolving blurry vision.References1–7:

  1. Wong TY, Mitchell P. Hypertensive Retinopathy. N Engl J Med. 2004;351(22):2310-2317. doi:10.1056/NEJMra032865.
  2. Bagheri Nika, Wajda Brynn N, Calvo Charles M, Durrani Alia K, Friedberg Mark A, Rapuano Christopher J. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease. Seventh edition. Philadelphia: LWW; 2016.
  3. Grosso A, Veglio F, Porta M, Grignolo FM, Wong TY. Hypertensive retinopathy revisited: some answers, more questions. Br J Ophthalmol. 2005;89(12):1646-1654. doi:10.1136/bjo.2005.072546.
  4. Henderson AD, Biousse V, Newman NJ, Lamirel C, Wright DW, Bruce BB. Grade III or Grade IV Hypertensive Retinopathy with Severely Elevated Blood Pressure. West J Emerg Med. 2012;13(6):529-534. doi:10.5811/westjem.2011.10.6755.
  5. James PA, Oparil S, Carter BL, et al. 2014 Evidence-Based Guideline for the Management of High Blood Pressure in Adults: Report From the Panel Members Appointed to the Eighth Joint National Committee (JNC 8). JAMA. 2014;311(5):507-520. doi:10.1001/jama.2013.284427.
  6. Haas AR, Marik PE. CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: Current Diagnosis and Management of Hypertensive Emergency. Semin Dial. 2006;19(6):502-512. doi:10.1111/j.1525-139X.2006.00213.x.
  7. Ophthalmology AA of. 2017-2018 Basic and Clinical Science Course. (MD HJI, ed.). S.l.: American Academy of Ophthalmology; 2017.

Identifier: Moran_CORE_23946


Glaucomatous Cupping

Home / Basic Ophthalmology Review / Optic Nerve

Title: Glaucomatous Cupping

Author: Tanner Ferguson, 4th year medical student, University of South Dakota Sanford School of Medicine

Glaucoma is a term used to describe damage to the optic nerve characterized by a progressive loss of retinal ganglion cells (RGCs). Although intraocular pressure is a proven, modifiable risk factor for the disease, elevated intraocular pressure is not sufficient for a diagnosis1,2. When damage occurs in glaucoma, changes can be detected structurally and/or functionally.  It is separated into open angle versus closed angle types, as well as primary and secondary.  This article primarily focuses on primary open angle glaucoma (POAG).  Glaucoma is a multifactorial disease process and this overview will provide a summary on the modifiable risk factors and signs/symptoms that suggest further evaluation. It is important to identify and manage these risk factors because glaucoma remains the world’s 2nd leading cause of blindness.3

In the optic nerve, there is a physiologic disk and an indentation absent of neural tissue known as the optic cup. In glaucomatous nerve damage, the retinal nerve fiber atrophies as fibers die and the cup increases in size. To monitor progression, clinicians track the cup-disc ratio and compare to age-matched normal values.4

Risk Factors for Open Angle Glaucoma

If you suspect a patient is at risk for glaucoma, there are numerous risk factors to consider5-7, some of which are listed below:

It is critical to screen for sleep apnea or other causes of nocturnal hypoxia (such as using blood pressure medications at night) because these are easily managed with CPAP or by modifying medication timing. Numerous reports have suggested nocturnal hypoxia to be a risk factor for glaucoma progression.8,9

Symptoms

Glaucoma is typically a silent, progressive condition that is often asymptomatic until significant damage has occurred10. Studies have reported that visual field deficits are not present until a significant amount of nerve fiber layer loss has occurred11. When visual symptoms do occur, patients often have a “tunneling” of vision where peripheral vision is often affected first. Unfortunately, once noticeable vision loss has occurred the disease is likely in its advance stages.  Thus, if you suspect a patient has early signs of glaucoma or has significant risk factors, it is crucial to encourage patients to seek further evaluation from their eye care provider.  The vision loss is most often a very slow, smoldering, progressive process that presents later in life but not infrequently a patient may have unusually high intraocular pressures or secondary glaucoma which can cause more rapid vision loss—once again emphasizing the importance of screening and appropriately referring patients.  Acute angle closure has a much different presentation, is typically painful with blurry vision and causes often very high intraocular pressures that can rapidly damage the optic nerve/retinal ganglion cells.  We have included several pictures below to demonstrate the appearance of glaucomatous cupping of the optic nerve.

Images:

References

  1. Heijl A, Leske MC, Bengtsson B, et al. Reduction of intraocular pressure and glaucoma progression: results from the Early Manifest Glaucoma Trial. Arch Ophthalmol. 2002;120(10):1268-1279.
  2. Wolfs RCW, Borger PH, Ramrattan RS, et al. Changing Views on Open-Angle Glaucoma: Definitions and Prevalences—The Rotterdam Study. Investigative Ophthalmology & Visual Science. 2000;41(11):3309-3321.
  3. Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. British Journal of Ophthalmology. 2006;90(3):262-267. doi:10.1136/bjo.2005.081224.
  4. Burgoyne CF, Downs JC, Bellezza AJ, Suh J-KF, Hart RT. The optic nerve head as a biomechanical structure: a new paradigm for understanding the role of IOP-related stress and strain in the pathophysiology of glaucomatous optic nerve head damage. Prog Retin Eye Res. 2005;24(1):39-73. doi:10.1016/j.preteyeres.2004.06.001.
  5. Tielsch JM, Katz J, Singh K, et al. A population-based evaluation of glaucoma screening: the Baltimore Eye Survey. Am J Epidemiol. 1991;134(10):1102-1110.
  6. Leske MC, Connell AMS, Wu S-Y, Hyman LG, Schachat AP. Risk Factors for Open-angle Glaucoma: The Barbados Eye Study. Arch Ophthalmol. 1995;113(7):918-924. doi:10.1001/archopht.1995.01100070092031.
  7. Prum BE, Rosenberg LF, Gedde SJ, et al. Primary Open-Angle Glaucoma Preferred Practice Pattern(®) Guidelines. Ophthalmology. 2016;123(1):P41-P111. doi:10.1016/j.ophtha.2015.10.053.
  8. Tielsch JM, Katz J, Sommer A, Quigley HA, Javitt JC. Hypertension, Perfusion Pressure, and Primary Open-angle Glaucoma: A Population-Based Assessment. Arch Ophthalmol. 1995;113(2):216-221. doi:10.1001/archopht.1995.01100020100038.
  9. Leske MC, Wu S-Y, Hennis A, Honkanen R, Nemesure B, BESs Study Group. Risk factors for incident open-angle glaucoma: the Barbados Eye Studies. Ophthalmology. 2008;115(1):85-93. doi:10.1016/j.ophtha.2007.03.017.
  10. Sommer A, Katz J, Quigley HA, et al. Clinically detectable nerve fiber atrophy precedes the onset of glaucomatous field loss. Arch Ophthalmol. 1991;109(1):77-83.
  11. Miki A, Medeiros FA, Weinreb RN, et al. Rates of retinal nerve fiber layer thinning in glaucoma suspect eyes. Ophthalmology. 2014;121(7):1350-1358. doi:10.1016/j.ophtha.2014.01.017.

Identifier: Moran_CORE_23937


Central Retinal Artery Occlusion

Home / Basic Ophthalmology Review / Retina

Title: Central Retinal Artery Occlusion

Author: Justine Cheng, 4th Year Medical Student, University of Iowa School of Medicine

Overview:

Central Retinal Artery Occlusion (CRAO) is an obstruction of the blood supply to the retina and has been crudely termed a “stroke of the eye.”  It is typically from an embolic source and frequently causes significant vision loss.  Treatment is controversial and typically underwhelming but the work-up has important clinical significance given the increased risk for additional future vascular events such as a CRAO to the other eye or a cerebral vascular accident (CVA).  If an isolated, distal arteriole is obstructed than it is categorized as a branch retinal artery occlusion rather than a CRAO.

Pathophysiology

The central retinal artery, which is a branch of the ophthalmic artery (OA), serves as the blood supply for the inner retina. The outer retina is supplied by the choriocapillaris of the choroid. Acute occlusion of the central retinal artery deprives nutrients and oxygen to the inner retina, which if prolonged causes irreversible ischemic damage. The exact timing of this irreversible ischemic damage is up for debate, but animal studies have shown that by four hours there is permanent nerve fiber damage. A subset of the population have a cilioretinal artery that supplies the retina between the fovea and optic nerve separate from the central retinal artery (Image A).  If patients have a cilioretinal artery, central vision occasionally may be spared.

Image A

Presentation

Patients typically present with sudden, dramatic, painless vision loss in one eye—count fingers or worse.  The patient should have a relative afferent pupillary defect (RAPD) in the affected eye. There may be incomplete visual field defects which can be detected on confrontational visual field testing. There is generally a diffuse retinal whitening with a cherry-red spot in the macula (Image B and C), retinal arterial attenuation (Image B) and optic disc edema.  These findings are not always present immediately but develop within hours of the event.  Occasionally the emboli can be observed in the retinal arterioles as a small, yellow and refractile body indicating a cholesterol embolus, or Hollenhorst plaque (see photo). If the embolus is small and pale, it may indicate a fibrin platelet embolus.

Image B

Image C

Further Testing

Although CRAO can be diagnosed clinically, fluorescein angiography can provide additional insight. It shows delayed filling of retinal arteries and delayed arteriovenous transit time, and can differentiate a CRAO from a BRAO, characterizing the extent of ischemic damage.  Ocular Coherence Tomography (OCT) will show edema and thickening of the inner retina in the short term and atrophy of the outer retina in the long term.

If the patient is over 60, ask about giant cell arteritis symptoms such as jaw claudication, scalp tenderness, proximal muscle weakness and have a low threshold to order inflammatory markers (ESR/CRP).  If elevated start high dose steroids and schedule a superficial temporal artery biopsy to diagnose giant cell arteritis.  When a CRAO occurs as a result of this vasculitic disease it is termed an “arteritic,” accounting for only 4.5% of all CRAO cases (Varma et al, 2013).  All other causes are termed “non-arteritic.”

For non-arteritic etiologies, the most common cause of CRAO is emboli from carotid arteries, of which 74% of these emboli are cholesterol, 10.5% are calcific, and the rest are fibrin (Varma et al, 2013). When the offending emboli is a cholesterol plaque and is visible on exam this is termed a Hollenhorst plaque.  Ask about the patient’s atherosclerotic risk factors such as diabetes, hypertension, peripheral vascular disease and coronary artery disease and carefully look for a Hollenhorst plaque.  Consider ordering a carotid ultrasound duplex to look for treatable carotid stenosis.  Alert the primary care physician to readdress their vascular risk factors, including an echocardiogram and electrocardiogram.  If the patient is young and has a paucity of vascular risk factors, consider a coagulopathy such as factor V Leiden and order a corresponding laboratory work-up.

Treatment

Treatment of CRAO is controversial and often unsuccessful.  Nonetheless, like treating stroke, time is vision and any attempt to improve the dramatic vision loss is worthwhile to the patient. Treatment modalities can be categorized into dislodging the emboli, improving oxygenation, and increasing retinal perfusion pressure by lowering intraocular pressure. Some of the modalities to accomplish these things include ocular massage, inhalation of carbogen, hyperbaric oxygen, performing an anterior chamber tap or giving oral acetazolamide to lower IOP.  Thrombolysis has also been suggested but due to adverse events and mixed results it is not generally recommended.

Prognosis and Complications

Prognosis depends on duration of occlusion and the presence of cilioretinal artery, but typically is poor. One study showed that when occlusion was transient, 87% of non-arteritic CRAO improved (Hayreh, 2007). 67% of those with cilioretinal artery also saw improvement (Hayreh, 2007). Most of the visual acuity improvement happened within the first week. Up to 20% of individuals may develop neovascularization of iris, which in turn can cause glaucoma (Hayreh, 2005).

References

Varma DD, Cugati S, Lee AW, Chen CS. A review of central retinal artery occlusion: clinical presentation and management. Eye (Lond). 2013 Jun; 27(6): 688–697.

Hayreh SS, Zimmerman MB. Fundus changes in central retinal artery occlusion. Retina. 2007 Mar;27(3):276-89.

Hayreh SS, Zimmerman MB. Central retinal artery occlusion: visual outcome. Am J Ophthalmol. 2005 Sep;140(3):376-91.

Graff-Radford J, Boes CJ, Brown RD. History of Hollenhorst Plaques. Stroke. 2015;46:e82-e84.

Bakri SJ, LUqman A, Pathik B, Chandrasekaran K. Is Carotid Ultrasound Necessary in the Clinical Evaluation of the Asymptomatic Hollenhorst Plaque? Trans Am Ophthalmol Soc. 2013 Sep; 111: 17–23.

Identifier: Moran_CORE_23930


Diabetes Mellitus/Diabetic Retinopathy

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Title: Diabetes Mellitus/Diabetic Retinopathy

Author: E Anne Shepherd, 4th Year Medical Student, University of Tennessee Health Science Center

Text:

Diabetes Mellitus is a medical condition that is seen and managed by every primary care physician and specialist around the world. According to data from the CDC in 2012, 29.1 million Americans (9.3% of the population) had received the diagnosis of diabetes and there are an estimated 1.4 million new diagnoses every year. 86 million Americans twenty years or older were categorized as “prediabetic”, which is increased from 79 million in 2010. The cost of diabetes was $245 billion in 2012 and the average medical expenditures of a diabetic patient was 2.3 higher than a nondiabetic counterpart. Diabetes plays a major role in care and management of many of our patients.

One of the main complications in diabetes is microvascular disease, which includes diabetic retinopathy, nephropathy, and neuropathy which lead to vision loss, end stage renal disease, and lower limb ulcers or amputations, respectively. This article is focused on diabetic retinopathy but it is important to understand that all microvascular diseases stem from the same processes which are happening throughout the entire body. The risk of developing retinopathy, as well as the other microvascular complications, is determined by the duration and severity of the hyperglycemia. In type I diabetes the onset is usually within fifteen to twenty years while in type II diabetes retinopathy can be seen even before the official diagnosis. It is important that both type I and II diabetic patients are counselled on the importance of yearly eye exams by an ophthalmologist.

There are multiple mechanisms at play in a diabetic patient that lead to retinopathy, including osmotic stress from sorbitol accumulation, injury from advanced glycosylated end products, oxidative stress from free radicals, and growth factors like vascular endothelial growth factor (VEGF).

The two main categories of diabetic retinopathy are nonproliferative diabetic retinopathy and proliferative diabetic retinopathy, which require separate treatment regimens. Nonproliferative diabetic retinopathy is characterized by leaky blood vessels causing macular edema. These vessels are often fragile and lead to small hemorrhages, called dot hemorrhages, and microaneurysms in the retina. Edema within the macula (the part of the retina responsible for central vision) can cause blurred vision and is now treated with an anti-VEGF intraocular injection, such as ranibizumab (Lucentis) or bevacizumab (Avastin). Proliferative diabetic retinopathy is characterized by the formation of new blood vessels in response to retinal ischemia. White areas in the retina, called “cotton wool spots”, are localized regions of ischemia and can be an early sign of proliferative retinopathy. Advance proliferation can lead to vitreous hemorrhages and retinal detachments. Patients should be explained the signs of retinal detachment, like increased floaters/flashes or the sensation of curtains being pulled over their eyes, and to call their ophthalmologist if they experience any of these. Proliferative diabetic retinopathy is treated with laser panretinal photocoagulation (PRP) to halt further progression of vision loss.

Images:

Image 1. Proliferative Diabetic Retinopathy with previous PRP scars. Flame hemorrhages and cotton wool spots (about 2 o’clock). PRP scars are seen along the periphery.

Image 2. Proliferative Vitreoretinopathy (PVR) with overlying hemorrhage. PVR is caused by previous retinal detachments leading to scars that prevent the retina from reattaching appropriately.

Image 3. Proliferative Vitreoretinopathy (PVR) with overlying hemorrhage. PVR is caused by previous retinal detachments leading to scars that prevent the retina from reattaching appropriately.

References:

Centers for Disease Control and Prevention. National Diabetes Statistics Report: Estimates of Diabetes and Its Burden in the United States, 2014. Atlanta, GA: US Department of Health and Human Services; 2014.

F. Fowler, M. J. (2008). Microvascular and Macrovascular Complications of Diabetes. Clinical Diabetes, 26(2), 77–82. https://doi.org/10.2337/diaclin.26.2.77

Jiao, et al. Effectiveness of the multidisciplinary Risk Assessment and Management Program for Patients with Diabetes Mellitus (RAMP-DM) for diabetic microvascular complications: A population-based cohort study. Diabetes & Metabolism Aug 2016; 42(6):424-432.

Identifier: Moran_CORE_23923


Chemical Burns

Home / Basic Ophthalmology Review / Trauma

Title: Chemical Burns

Author: E Anne Shepherd, 4th Year Medical Student, University of Tennessee Health Science Center

Text:

The first step in assessing a patient who is believed to have suffered a chemical injury to the eye is to obtain a history of the incident and identify the offending chemical. This should NOT delay treatment though. Key to emergency treatment is irrigation, irrigation, irrigation. If the patient calls from home, advise them to irrigate their eye(s) with clean water for a minimum of thirty minutes before coming in. If the patients is presenting to the emergency room, isotonic saline or lactate ringer solution should be used to irrigate. Irrigation should be continued until a neutral pH is achieved; this could require up to 20 liters. Adequate irrigation is significantly easier when the patient’s ocular surface is anesthetized with topical anesthetics such as 1% proparacaine.  Remember that these drops are toxic to the eye when used for extended periods.  The patient should NEVER be prescribed or given topical anesthetics for pain control.  Once adequate irrigation is completed a thorough ophthalmic exam is necessary to assess the damage. It is important pay attention to the fornices, visual acuity, intraocular pressure and assess for limbal blanching.

If the chemical composition of the insulting agent is unknown and cannot be identified poison control can be contacted for more information. Items commonly causing injury to eye are listed below.

Table 1. Etiologies of common acid burns:

Chemical Example of common item containing chemical
Sulfuric Acid Batteries, industrial cleaner
Hydrochloric acid Laboratory accidents
Sulfurous acid Bleach, Refrigerant, fruit and vegetable preservatives
Hyrdofluoric acid Glass polisher, gasoline alkylation, silicone production

 

Table 2. Etiologies of common alkali burns:

Chemical Example of common item containing chemical
Ammonia Fertilizers, refrigerants
Lye Drain cleaner
Lime Plastic, mortar, cement, whitewash
Potassium hydroxide Soft soaps, chemical cuticle remover in manicures, unhairing stage of tanning process
Magnesium hydroxide Sparklers, incendiary devices

In general, alkali burns are more harmful and cause more damage than acid burns. Alkali solutions are lipophilic and therefor penetrate the eye more rapidly and have the potential to deposit in the ocular tissues. Acids, on the other hand, cause precipitation of proteins which creates a barrier and prevents further damage in most cases. If the damage to the cornea is severe enough in either an acid or alkali burn, there can be destruction to the limbal stem cells causing limbal stem cell deficiency (link). Loss of these stem cells creates opacification and neovasculatization of the cornea. Other complications that can arise are increased intraocular pressure from inflammatory changes and direct damage to the trabecular meshwork, scarring and forniceal shortening, lifelong dryness from loss of goblet cells, and symblepharon formation from epithelial destruction (see Image 1).

Treatment includes antibiotic eye drops, cycloplegic/mydriaic drops for comfort, topical lubricants like artificial tears, and pressure lower drops, if necessary. Achieving corneal epithelization is important to prevent further inflammation and corneal damage. In severe burns that are complicated by persistent corneal epithelial defects, this can be aided by bandage contact lens, botox induced ptosis, or amniotic membrane grafts.

Images:

Image 1: Anterior symblepharon after a severe alkali burn. Symblepharon are prevented by not allowing the non-epithelialized surfaces of the cornea/sclera and the conjunctiva to come in continuous contact.

Image 2. Neovascularization of the cornea with diffuse corneal edema. This can present after both severe acid and alkali burns and are due to damage to limbal stem cells.

 

References:

Augsburger JJ, Corrêa ZM. Chapter 19. Ophthalmic Trauma. In: Riordan-Eva P, Cunningham ET, Jr. eds. Vaughan & Asbury’s General Ophthalmology, 18e New York, NY: McGraw-Hill; 2011.

Singh P, Tyagi M, Kumar Y, Gupta KK, Sharma PD. Ocular chemical injuries and their management. Oman Journal of Ophthalmology. 2013;6(2):83-86. doi:10.4103/0974-620X.116624.

Identifier: Moran_CORE_23919


Introduction to the Clinical Ophthalmology Medical Student Rotation at Moran Eye Center

HomePrinciples of OphthalmologyExaminations


Title: Introduction to the Clinical Ophthalmology Medical Student Rotation at Moran Eye Center
Authors: Chris Bair, MD and Tyler Quist, MD
Date: 05/23/2017
Secondary CORE Category: Basic Ophthalmology Review
Keywords/Main Subjects: medical student, exam, education
Description of Video: This brief video from fourth-year medical students Chris Bair and Tyler Quist discusses the details of your ophthalmology rotation at the Moran Eye Center, as well as providing a primer on how to use the slit lamp and perform a basic eye exam.
Format: Video
Series: Medical Student Education
Identifier: Moran_CORE_23693
Copyright statement: Copyright Chris Bair, MD and Tyler Quist, MD, ©2017. For further information regarding the rights to this collection, please visit: http://morancore.utah.edu/terms-of-use/