Medical Bulbs

Everything there is to know about medical bulbs

Medical bulbs are simply the various sources of light in medical practice. Bulbs provide illumination to an environment, making nearby objects and people easily seen and assessed. In most instances, lighting is nearly as important as the naked eye. Illumination is, however, of natural and artificial types. Natural illumination is provided by sunlight and moonlight, while the lighting from bulbs, candlelight, lamps, and other human-made sources is regarded as artificial illumination. 

Lighting from a bulb is equally vital in hospital practice. The work area has to be suitably lit. Most importantly, many medical equipment types use specified bulbs for the various procedures for which they are intended. These equipment pieces are mostly of diagnostic purposes and can also be found in ophthalmic and dental medicine. 


The first electric light was developed in 1802 by Humphry Davy. However, the design was very crude, with no commercialization process. It took several decades of improvement before bulbs became everyday household items. The design of incandescent light and its commercialization were done by Thomas Edison and his company in 1879. 

The incandescent electric bulb was used in medical practice till the late 1950s when halogen bulbs were available commercially. Incandescent bulbs use more energy and get very hot. The introduction of halogen bulbs saw a significant drop in energy usage. They have an incredible life span too. Although they can get pretty hot due to the infrared rays transmitted, both types of bulbs afford an excellent physician clarity of details during use. However, LED (light-emitting diodes) lamps were introduced in the 2000s, serving as an improvement to halogen light. They have better energy optimization and life span than halogen lamps. The initial problem was that the color temperature emitted was too blue to work with. Its illumination is not bright enough for medical processes. This has been improved, and, nowadays, LED lamps used in practice emit a color temperature of 3600-degree Kelvin, bright enough for delicate procedures. A medical bulb, today, can be a type of halogen, fluorescent or LED bulb. 

Indications to use a medical bulb

Medical bulbs are used in different hospital equipment for various purposes. The indications are highlighted below;

  • Ophthalmic uses. Medical bulbs are used in ophthalmic equipment such as; slit lamps (used to shine light into the eye), retinoscopes (for illuminating and examining internal eye in the determination of refractive eye power), ophthalmoscopes (to check the inside fundus of the eye and other structures), fiber optic illuminators (for many optical procedures) and eye chart projectors (for vision testing). 
  • Dental uses. A medical bulb is found in dental equipment such as dental curing (for the polymerization of light cure resin composites). Other types of dental equipment include a handpiece and dental exam light. 
  • Patient examination and diagnostic purposes. These include:
    • penlight bulbs for quick examination of reflexes, pupil activity, and other similar small details; 
    •  otoscope bulbs (for illuminating and examining a patient ear and throat);
    • transilluminator bulbs used to shine a light directly on muscles or sinuses to aid the diagnosis of a disease or infection;
    • audiometer bulbs, used in audiology or otolaryngology to assess a patient's hearing capability;
    • dermatoscopes also use a light source and a magnifier to examine skin lesions on a patient;
    • Laryngoscopes also use bulbs to view the throat during endotracheal intubation, larynx surgery, and other related procedures;
    • rigid endoscopes such as colposcopes, proctoscopes, anoscopes, and vaginal specula require illumination of the examination area;
    • ENT illuminator bulbs for the examination of the nasal cavity, larynx, etc.
  • Bilirubin lamps provide phototherapy that helps breakdown excess bilirubin into soluble derivatives that can be flushed out of the system. They use it in the treatment of neonatal jaundice. 
  • Surgical light. Operating theatres make use of overhead medical bulbs (LED light sources). There are also headlight lamps used for surgical procedures, emergencies, and several minor procedures.
  • Laboratory procedures also use light sources. It can be found in microscopes, germicidal lamps, and so on. 

Recent advances in medical lighting use include NIR-II fluorescence imaging for cancer detection and its photodynamic therapy, optical coherence tomography for arthroscopic use, two-photon polymerization process for 3D bioprinting of living cells, and so on. 

Complications of using medical bulbs

General complications of bulbs led to design improvements, from incandescent to halogen/halide lamps and then, most recently, LED lamps. Incandescent light sources consume relatively the highest energy, emitting high infrared energy, which causes bulb hotness. Halogen lamps also exhibit similar use problems but at a far lower rate. The new LED lamps are quite the best option of use.

Phototherapy may show side effects such as redness, dry skin, itchy skin, nausea, folliculitis, and blisters. Phototherapy using halogen light may cause increased insensible water loss through the skin. Drug-induced photosensitivity can also develop when a patient is exposed to medical light. Manifestation includes cutaneous reactions, amongst others. 

Some disorders have been associated with bedtime exposure to light. The disorders can be of sleep, mood, gastrointestinal, or the cardiovascular system. 

Alternative equipment

Medical bulbs do not have any worthy alternatives. Although LED lamps may be the best option in most situations, the halogen lamps, fluorescent bulbs, and incandescent light remain plausible alternatives. Natural illumination from the sun and moon are good enough for general medical examinations.

General specifications

The general specifications of a medical bulb are detailed below;

  • Color. White lighting with blue tinge gives a sharp, clear appearance that is fit for hospital use
  • Finish. The bulb finish could be clear, frosted or pearl.
  • Color temperature suitable for medical use may include 3500K (white), 4000K (cool white), 5000K (daylight) and 6500K (natural daylight).
  • Color rendering index. This measure shows how closely a light source mimics the natural sunlight. It is measured on a scale of 1 – 100 Ra, with 100 Ra signifying sunlight. The International Electrotechnical Commission (IEC) specifies a minimum of 85 for light sources used for medical and surgical purposes. Most new medical bulbs now have a color rendering index of greater than 90 Ra. 
  • Light output. The light output is the total quantity of light falling on a surface per square meter. It is also known as illuminance (E) and can be measured in Lumens (luminous flux) or Candela (luminous intensity) per square meter. The light output varies significantly depending on the purpose of the bulb. The minimum requirement for a diagnostic or examination lamp is 1000 lux. An illuminance of 500 lux is enough to lit up a room. 
  • Voltage requirement is typical 120V
  • Power requirements. A LED lamp consumes the least energy, higher than halogens or fluorescent lamps. A 4W LED light source could emit the same light output as a 50W halogen lamp. 

How they work

A medical bulb illuminates the human body, surfaces, and objects by casting light rays on them to make them clearer and brighter. Fluorescent lamps work by ionizing mercury vapor in a glass tube. This causes the electrons to emit photons at UV frequencies. The UV light is then converted to visible light by the phosphor coating inside the glass tube. 

Halogen lamps use tungsten filament encased in a small quartz envelope, which also houses one type of halogen gas. The halogen vapor combines with tungsten atoms as they evaporate. They then get redeposited on the filament, and the recycling process continues. A LED bulb passes an electric current through a semiconducting material (diode). The diode then emits light photons through electroluminescence. 

A medical bulb can also deliver light rays that can interfere with biological and biochemical processes. This can be seen in phototherapy such as neonatal jaundice, psoriasis, and so on. In the neonatal jaundice phototherapy, the light rays convert unconjugated bilirubin into water-soluble isomers that are excreted in the urine. 

Market Leaders

The top manufacturers of medical equipment include;

  • Welch Allyn. Welch Allyn is one of the earliest manufacturers of medical bulbs. The company was founded in 1915. Today, they are a leading manufacturer of halogen lamps, vacuum and gas incandescent lamps, metal halide lamps, high-intensity discharge lamps, etc. 
  • ACEM is a top brand that produces lamps for general medicine, dermatology, gynecology, and dentistry.
  • Amensco®. This brand offers various germicidal and UV lamps.
  • HFMED®. From Shanghai Huifeng medical instruments, the brand offers various general-purpose medical lamps and other photo equipment. 
  • Haag-Streit. This company is a leading manufacturer of ophthalmic bulbs, especially. The company has been around for over 150 years, and they continue to deliver excellence throughout the years.
  • Dentsply Sirona is a leading manufacturer, too, with some specialization in dental equipment and bulbs.
  • Topcon western ophthalmics. This is a company with over 40 years of excellence. As the name implies, they offer top-notch ophthalmic equipment and bulbs. 


The use of a medical bulb is an agelong practice for patient care. It started as general-purpose usage before using specialized medical bulbs for patient examination, diagnosis, and therapy. Today, they are the most crucial component of many scientific, dental, ophthalmic, and other hospital equipment. LED lamps' development feels like the most optimal electric light discovery, but science is never self-limiting. 

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