Bea Palileo, M.D., Benjamin Lin, M.D.
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Welcome to the whole new world of ophthalmology! This article includes helpful tools to begin your first ophthalmology rotation as a medical student. This overview consists of basic ophthalmologic terminology, ocular history and physical exam (with a printable eye clinic template), common eye diseases, and EyeGuru pearls to ace your ophtho rotation.
Eye Terminology
First, you will need to learn a new language! As you will soon discover, ophthalmologists use several abbreviations and terminology unique to this field. To decode all of those pesky ophtho abbreviations, here is a link to an ophtho translator (https://eyeguru.org/translator/). You can type in individual terms or copy/paste entire notes to start learning. Also included is the most comprehensive online list of common ophthalmology abbreviations, if you prefer the old-fashioned way.
Ocular history
We will highlight questions you should ask targeting specific eye concerns in addition to the regular routine medical history taking.
History of Present Illness (HPI):
Start by obtaining their chief complaint, then continue to target specific concerns regarding the patient&#;s eyes as needed. Ask about 5 categories: vision changes, ocular pain, abnormal ocular secretions, abnormal appearance, and trauma.
Past Ocular History (POhx)
Ocular Medications (Gtts)
There are three important things to record when it comes to ocular medications (the type, the frequency, and the laterality&#;right eye or left eye). You will soon discover that the knowing the color of the eye drop type will be crucial as many patients know their medication by color instead of name.
Other important medical history
Remember that the eye is connected to the rest of the body, so don&#;t forget all the important parts of a routine medical history!
Ocular physical exam
Ophthalmic vitals (Visual Acuity, Intraocular Pressure, and Pupils)
External examination
Slit Lamp Examination (SLE)
Dilated Fundus Examination (DFE)
The fundus , the retina, the back of the eye are all words that are used interchangeably by ophthalmologists. There are two ways to visualize the posterior segment of the eye:
Here is the list of posterior segment structures that can be visualized using the techniques above with some things you should be looking for:
Eye clinic template
The ocular history and physical exam can seem overwhelming and difficult to remember at first. Here is an eye clinic template that you can bring to clinic.
Download template here: Ophtho clinic template
Template preview:
Ocular imaging
There are several unique imaging modalities that are used daily in ophthalmology. We will outline each of them here:
Common eye diseases
The bread and butter of ophthalmology includes the following diseases: cataracts, dry eye syndrome, corneal abrasions and ulcers, age-related macular degeneration, diabetic retinopathy, and uveitis.
Our pathology frameworks in the residency essentials section covers the basics of how to diagnose and manage these diseases: https://eyeguru.org/residency-essentials/
Other resources
If that wasn&#;t enough information already, here is a comprehensive review of the best ophthalmology resources available: https://eyeguru.org/blog/ophtho-resource-guide/.
EyeGuru pearls
Once we have convinced you to join the dark side into the microscopic world of ophthalmology, check out the following articles to guide you towards a successful ophthalmology interview match! https://eyeguru.org/blog/planning-for-ophtho-interviews/.
References
Overview
Light Amplification by Stimulated Emission of Radiation (LASER) therapy utilizes a highly specific and concentrated beam of light that can be used to alter tissues in the medical treatment of disease (i.e., medical grade lasers). Since the times of ancient civilizations who used sunlight to remedy skin diseases, the use of light in clinical therapy has continued to grow with modern technology and scientific knowledge to become what laser treatment is now today.[1] Laser is utilized in procedures of almost all medical fields (e.g., dermatology, cardiology, oncology, neurosurgery, plastic surgery, general surgery, etc.).[2][3] In particular, laser use has become especially emphasized in the field of ophthalmology due to the eye&#;s innate transparent and focusing properties as an optical device. Just as it facilitates the transmission of natural light, the transparent cornea and media also allow laser light to reach and affect almost all tissues of the eye.[4] The efficacy and safety of specific low energy lasers combined with minimal invasiveness make laser an ideal modality for both diagnostic imaging and clinical treatment of eye pathology.[3][5][6][7]In fact, its ease of use allows it to be performed in a variety of outpatient settings.
Lasers are now so commonplace that it can cause complacency. However, there are risks to the eye accompanied with laser use. Laser surgery is still a form of surgery, and its risk profile must be adequately assessed as such. Furthermore, safety guidelines and complications unique to lasers must also be taken into careful consideration. Similarly, the use of lasers in non-medical contexts requires a need for understanding of the impact that can be had on the eyes, as these situations can often be much less regulated.
Background
Light is released when excited electrons return to their original energy levels and emit photons of electromagnetic energy. Laser light is differentiated from other light sources (such as sunlight or a light bulb) due to several specific properties. Laser beams are typically monochromatic (single wavelength) and collimated (parallel light rays). Most importantly, lasers are coherent (the electromagnetic waves are in phase with each other in both space and time).[5] The light is amplified by stimulated emission of radiation (i.e., LASER). The combination of these characteristics distinct to lasers is critical for its precise and powerful application.
Medical Laser Exposure
A laser beam&#;s parameters may be adjusted based on intended use and the target. Each wavelength and power setting in laser can be chosen based on the delivery system, procedure, and type of tissue or pathology that is to be treated.[3][5] For example, an infrared diode laser (at a wavelength of 806-810nm) may be used for retinal photocoagulation while an ultraviolet excimer laser (at 193 nm) may be used for corneal reshaping. Ophthalmic lasers have different tissue parameters that allow them to exert a wide variety of beneficial clinical effects on ocular tissue (e.g., photoablation, photocoagulation, fragmentation, or perforation).[2] These same beneficial effects of laser therapy, however, can result in risk of ocular damage.
In the clinic, ophthalmic lasers are often directly controlled by the operator surgeon (typically via a foot pedal control). The intended energy burst then travels along a fiber optic cable to a device that transforms and transmits the collimated laser beam to the target. Lasers may also have a second reference targeting laser beam in order for the treating surgeon to visualize where the treating laser beam energy will land. Just as the type of laser varies, the device for delivery can also change. In ophthalmology, laser delivery devices include slit lamps, operating microscopes, intraocular probes, and indirect ophthalmoscopes.[5][8]
Non-medical Laser Exposure
Apart from their therapeutic applications, lasers are also employed in community, laboratory, industrial, and military settings.[9][10]
In the community setting, lasers can be easily accessed in a variety of forms (e.g., laser pointers, laser scanners, laser projectors). Community-acquired laser injuries are normally transient and less severe as commercially available lasers are less potent.
In the laboratory and industrial settings, lasers are used for research and manufacturing (e.g., cutting, welding) purposes. Laboratory and industry-acquired laser injuries are more severe due to the intensity of lasers used in these settings. Such laser injuries are preventable and almost always occur when there is failure to comply with equipment operation guidelines or eye safety regulations.
Military lasers are widely applied in security, tactical, communication, and other military systems. The use of lasers as weapons to cause permanent blindless is strictly prohibited by the Geneva Conventions and the United Nations&#; Protocol on Blinding Laser Weapons. However, laser eye injuries are still present in the military setting often due to accidental exposure or unintended use.
It is important to note that laser injuries in almost all settings are likely underreported because of potential legal consequences for protocol violations and perhaps military restrictions.[9][10]
Even though community and commercially available lasers have limited hazard potential, they can still engender adverse outcomes when used inappropriately. In the United States, it is illegal to aim a laser pointer at an aircraft or its path. This prohibition is due to the distraction, temporary visual disturbance, and view obstruction to the pilot -- not because of harm to their eyes. Even the most potent and hazardous Class IV lasers are unlikely to cause eye injury due to the great distance and layers of environmental barriers between an aircraft and the ground.[11]
Similar distracting and temporarily restricting uses of laser can also be found at public protests and demonstrations. Deliberately aiming a laser into the eyes of either protestors or police would be inappropriate operation of a laser device. However, even at very close proximity, such action would still likely not result in permanent eye injury. Owing to body movements as well as aversion reflexes, the conscious individual would not remain still long enough for a laser to inflict irreversible damage.[12]
Compared to medical lasers, less potent non-medical lasers do not cause the same severity of ocular injury. Nevertheless, it is imperative that proper use guidelines and restrictions are followed in order to maintain safety and well-being.
Hazard Risk
Medical use of lasers in surgery constitutes a form of bladeless surgery, and it carries some of the corresponding risks and potential complications associated with conventional blade cutting surgery. According to the U.S. Food and Drug Administration (FDA), these include, &#;incomplete treatment, pain, infection, bleeding, scarring, and skin color changes.&#;[6]
Laser therapy however also introduces additional and unique risks. The FDA categorizes all manufactured laser products into four major hazard classes labeled Class I to IV. Class I lasers are non-hazardous (e.g., laser printers and DVD players); Class II lasers are low hazard but only when viewed directly for long periods of time (e.g., bar code scanners); Class III lasers are potentially significantly hazardous to eyes with direct viewing (e.g., laser pointers); and Class IV lasers are significantly hazardous to eyes and skin (e.g., research and medical lasers).[13]
Reflected Beams
The most frequent cause of accidental laser ocular exposure is reflected beams.[7] Class IV lasers are significantly hazardous because these reflected beams pose considerable exposure risk and ocular protection is required.[13] Light reflects off flat, specular (mirror-like) surfaces, and many pieces of equipment in the operating room are made of such material. Surfaces closest to the lasers, such as surgical instruments and delivery devices, are often metallic and reflective. Reflection can also occur from the patient&#;s cornea or contact lenses used in surgery.[7] It is important to note that some ophthalmic lasers extend into the ultraviolet and infrared wavelengths, making the reflected beams not visible to the human eye and thus the risk may be difficult to detect.
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Hazard Zones
Due to its limited divergence, laser light remains concentrated even at further distances. This makes the Nominal Hazard Zone (NHZ), or the area where direct, reflected, or scattered beams could cause adverse effects, more expansive and difficult to predict.[7][13]
Reduced Reflexes
The corneal blink reflex causes an individual to involuntarily close their eyelids following sensory stimulation to the cornea. This unconditioned reflex response is a protective mechanism used to shield the individual from unwanted irritants (e.g., bright lights or noxious chemicals) and typically is sufficient to protect against most long duration low hazard laser exposure.[14] Under anesthesia however, a patient&#;s blink reflex is greatly diminished or completely abolished and continues to be absent for hours, even after the return of consciousness and ability to blink on command.[15] While bright sunlight would already warrant a blink response, laser light can be millions of times more radiant than the sun. A patient under surgical anesthesia would be unable to perform the normal aversion response to protect their eye from intense heat or light produced by laser.[7]
Focused Light
Structures of the eye function to focus light onto the retina in order to produce images for vision. Likewise, the eye can also focus laser beams to concentrated areas on the retina, adversely resulting in inadvertent laser burns.[13]
Fire Hazards
Class IV lasers as well as their reflected beams present fire hazards.[13] Accidentally misfired, stray, and reflected beams can ignite surgical drapes, causing serious heat injuries to patients and others in the treatment area.[7]
Clinical Presentation
Laser injury, whether from medical or commercial lasers, can result in considerable legal, ethical, financial, and medical consequences.[16] Thus, it is important for ophthalmologists to be able to distinguish true laser injury from other underlying problems.[17]
Signs and Symptoms
Laser injury may be unilateral or asymmetric and bilateral depending on the type and duration of laser exposure.[17][18] Patients with acute exposure to a high-density laser may complain of seeing a bright flash of light (even if the laser wavelength is not in the visible light spectrum) followed by loss of visual acuity in phototoxicity. Patients with a laser injury may complain of transient ocular pain or headache, a visual scotoma, photophobia, metamorphopsia, or dyschromatopsia. Chronic pain, redness, or irritation of the eyes, face, or head are typically not attributable to laser injury and may suggest another underlying problem.[16][19]
Physical Examination
Typical examination findings of laser phototoxicity include tissue hemorrhage, perforation, or scarring.[17] Visual abnormalities and retinal lesions have been described in laser phototoxicity. In addition to careful dilated ophthalmoscopy, tissue injury may be better visualized and documented with ancillary imaging techniques including: adaptive optics scanning laser ophthalmoscope (AOSLO), fluorescein angiography (FA), fundus autofluorescence (FAF), and optical coherence tomography (OCT).[16][19]
Vitreous:
Pupil:
Anterior chamber / iris:
Lens:
Anterior chamber/iris:
Visual field:
Vitreous:
Retina:
Prognosis
The smaller and greater distance the lesion is from the fovea (which supplies the highest resolution central vision), the better the visual prognosis. In mild or focal ocular phototoxicity cases even when involving the macula, the visual acuity may significantly improve and stabilize over days to months. More severe, larger, or subfoveal lesions may however lead to permanent chorioretinal scarring. Macular hole, macular cyst, choroidal neovascularization, and preretinal membrane formation have all been reported however after laser injury.[17][18]
Management
There is no standardized protocol for the evaluation and treatment of laser-induced retinal injury.[17] Although intravenous and oral corticosteroids have been proposed to reduce the adverse cellular inflammatory responses (e.g., macular edema), but there are also potential treatment side effets.[18] Vascular endothelial growth factor (VEGF) inhibitors and photodynamic therapy may be helpful in treating choroidal neovascularization.[17][19] Surgery is typically not indicated, but some patients with unresolved complications (e.g., macular hole, epiretinal membrane) may benefit from surgical removal of scar tissue or hemorrhage.[18]
Laser Safety
In the United States, there are currently two general safety standards for medical application of lasers. The American National Standard for Safe Use of Lasers in Health Care, last updated in , is a guide for safe use of lasers in health care (ANSI Z136.3).[9] It is a voluntary standard, but it is often referenced in establishing and reviewing medical laser safety policies. The other standard is the FDA&#;s Code of Federal Regulations, last updated in , which has mandatory electronic product regulations for manufacturers of laser products (Title 21 &#; Food and Drugs, Subchapter J &#; Radiological Health).[10] This standard delineates the required certifications, labels, information, and directions for laser products.
[5][7][23]Environment and Equipment Safety
Staff and Bystander Safety
In summary, ophthalmic lasers comprise a critical part of the treatment armamentarium for ophthalmic disease but pose some risk to both the laser operator and patient. Specific precautions and training are necessary to ensure appropriate patient and physician safety.
References
Jelínková H. Introduction: the history of lasers in medicine. In: Lasers for Medical Applications: Diagnostics, Therapy and Surgery. Elsevier Ltd; :1-13.
Lin J-T. Progress of medical lasers: Fundamentals and applications. Med Devices Diagnostic Eng. ;2(1):36-41.
Khalkhal E, Rezaei-Tavirani M, Zali MR, Akbari Z. The evaluation of laser application in surgery: A review article. J Lasers Med Sci. ;10(Suppl 1):S104-S111.
Austin Health. Lasers in Ophthalmology. Victoria, Australia: Dept of Ophthalmology; .
Cordero I. Understanding and safely using ophthalmic lasers. Community Eye Heal. ;28(92):76-77.
Medical Lasers. FDA.gov. https://www.fda.gov/radiation-emitting-products/surgical-and-therapeutic-products/medical-lasers#lrps. Published September 28, . Accessed December 22, .
Sliney D. Ophthalmic laser safety. In Fankhauser F, Kwasniewska S, eds. Lasers in Ophthalmology: Basic, Diagnostic and Surgical Aspects. The Hague, The Netherlands: Kugler Publications; :1-10.
Laser, Ophthalmic. Plymouth Meeting, PA: World Health Organization; .
American National Standards Institute. American National Standard for Safe Use of Lasers in Health Care. Orlando, FL: Laser Institute of America; .
CFR - Code of Federal Regulations Title 21. Silver Spring, MD: U.S. Food and Drug Administration; .
Marshall J, O&#;Hagan JB, Tyrer JR. Eye hazards of laser &#;pointers&#; in perspective. Br J Ophthalmol. ;100(5):583-584.
Marshall J. The safety of laser pointers: Myths and realities. Br J Ophthalmol. ;82(11):-.
Frequently Asked Questions About Lasers. FDA.gov. https://www.fda.gov/radiation-emitting-products/laser-products-and-instruments/frequently-asked-questions-about-lasers. Published March 7, . Accessed December 22, .
Peterson DC, Hamel RN. Corneal reflex. Encyclopedia of Autism Spectrum Disorders. Springer, New York: StatPearls Publishing; :802-802.
Marelli RA, Hillel AD. Effects of general anesthesia on the human blink reflex. Head Neck. ;11(2):137-149.
Mainster MA, Stuck BE, Brown J. Assessment of alleged retinal laser injuries. Arch Ophthalmol. ;122(8):-.
Burling-Phillips L. Managing retinal injuries from lasers. EyeNet Mag. .
Barkana Y, Belkin M. Laser eye injuries. Surv Ophthalmol. ;44(6):459-478.
W. Commiskey P, J. Heisel C, M. Paulus Y. Non-therapeutic laser retinal injury. Int J Ophthalmic Res. ;5(1):321-335.
Waage et al. Non-therapeutic laser injury. Physiol Behav. ;176(1):139-148.
Huang A, Phillips A, Adar T, Hui A. Ocular injury in cosmetic laser treatments of the face. J Clin Aesthet Dermatol. ;11(2):15-18.
Princeton University. Section 2: Laser Hazards. Ehs.princeton.edu. https://ehs.princeton.edu/book/export/html/363. Accessed January 26, .
Lee W. Ocular Laser Safety. Ophthalmologyweb.com. https://www.ophthalmologyweb.com/Featured-Articles/-Ocular-Laser-Safety/. Published January 24, . Accessed December 23, .
Dick HB, Schultz T. A review of laser-assisted versus traditional phacoemulsification cataract surgery. Ophthalmol Ther. ;6(1):7-18.
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