Ophthalmic Microscopes

Everything you need to know about ophthalmic microscopes

A "microscope" is an instrument that magnifies objects too small to be seen by the naked eye. An "ophthalmic microscope" is an optical device specifically designed for use in treatments related to the eyes. This device is also known as an "ophthalmic operating or surgical microscope." One can have detailed images of the eye and its internal structure while using this instrument. When choosing an ophthalmic microscope, it is vital to keep in mind the type of optics required. At low light intensity, one can have high-quality images only by using an apochromatic lens that tends to transmit high-quality light. These instruments continue to evolve and have already enabled the introduction of new operations, which promise safer and more specific surgeries.

History of ophthalmic microscopes

The use of operating microscopes in ophthalmology goes back over one hundred years. It was the field of Ophthalmology that utilized the microscopes in surgeries for the very first time.

In 1911, ophthalmic surgeons had the first binocular operating microscope for surgery. In 1921-1938, Carl-Olof Nylén from Sweden experimentally used a "monocular Brinell-Leitz microscope," giving 10-15x magnification. The first use of a "binocular microscope" in surgery was reported in 1946. The title of "father of ophthalmic microsurgery" goes to Richard A Perritt of Chicago, the first ophthalmologist on record to use a binocular microscope in surgery in 1946. This instrument had a choice of magnification by changing eyepieces to give 3.5x, 7.0x, and 10.5x. A binocular dissecting microscope and a slit-lamp (1948) were developed by Dr. Hans Littmann. In 1961, Littmann developed a system with which assistants could view the surgical field as well. This system involved two microscopes and was called a Diploscope. 

The latest surgical microscope was launched in the United States and Japan in October 2017. Its latest versions were able to magnify an object by 1500 times with a limit of 0.2μm in spatial resolution.

Advantages and indications of ophthalmic microscopes

Microscopes have become an essential tool in ophthalmic surgery. Previously, cataract surgeries were performed without any magnification. However, techniques such as phacoemulsification have evolved and brought revolutionary changes in the field of ophthalmology. These devices offer high magnification and effective illumination sources fundamental to most sophisticated surgeries. Due to this instrument, surgeons can treat pathologies more clearly, with better magnification, appropriate lighting, and viewing capacity for an assistant. The eye surgeries that require modern advanced ophthalmic microscopes are described below:

  • ECCE TECHNIQUE – Extracapsular Cataract Extraction with Posterior Chamber Intraocular Lens Implant can be precisely performed under high magnification to avoid damage.
  • ICCE TECHNIQUE – Intracapsular Cataract Extraction (ICCE) refers to the removal of the entire lens, which can be precisely performed using this operating machine.
  • CATARACT SURGERY – Statistically speaking, the most common procedure in Europe is cataract surgery. A person requires cataract surgery when such starts seeing things blurry because the lens has deteriorated and is now opaque due to aging. With this revolutionary device, the ophthalmic surgeon can make his incisions accurately.
  • INTRAOCULAR LENS (IOL) IMPLANT –  following cataract surgery, there are numerous reported post-operative complications of an intraocular lens implant. These are best avoided using such ophthalmology devices.
  • CONGENITAL AND SOFT CATARACTS – can be precisely performed under high magnification with an ophthalmic microscope to avoid damage.
  • TRABECULOTOMY –  is a surgery to treat glaucoma, and it requires an ophthalmic microscope is to perform this surgery. Lens complications following peripheral iridectomy can be minimized with the use of an ophthalmic microscope. The apt magnification for glaucoma surgery is 16X or 10X.
  • CORNEAL GRAFT – With the help of an ophthalmic microscope, the surgeon can suture the donor graft to the recipient with precision. Furthermore, deep lamellar corneal grafts are very tough to deal with unless done under high magnification.
  • VITRECTOMY: Eyes that were previously inoperable because of injury leading to vitreous hemorrhage can now be operated on by vitrectomy. Closed vitrectomy is one of the various surgical procedures which can only be performed with an ophthalmic microscope. 

Clinical applications

  • CORNEAL CONFOCAL MICROSCOPY: is a relatively new technique for the study of corneal cellular structure. Pathologic and infectious conditions, along with corneal dystrophies and ecstasies, can be better treated and noticed with this instrument. Contact lens-induced corneal changes and pre and post-surgical evaluations are made easy because of such instruments.
  • OPTICAL COHERENCE TOMOGRAPHY: is a noninvasive imaging technology used to obtain high-resolution cross-sectional images of the retina to aid in the early detection and diagnosis of retinal diseases.
  • SLIT LAMP: is a microscope with a bright light used during an eye exam. It is a key tool in determining the health of the eyes and detecting eye diseases.
  • OPHTHALMOSCOPY: also known as fundoscopy, is a test that allows an ophthalmologist to see inside the fundus of the eye and other structures using an ophthalmoscope. An ophthalmologist uses ophthalmoscopy to screen for eye diseases and conditions that include damage to your optic nerve, retinal tear or detachment, glaucoma, macular degeneration, cytomegalovirus (CMV) retinitis, melanoma, and hypertension.

Complications

  • MUSCULOSKELETAL DISORDERS: 62% of the microscope users in a study declared suffering from musculoskeletal problems while 58% faced it repetitively.
  • VISUAL PROBLEMS: 94% of subjects in a study mentioned some form of vision problems ranging from eye discomfort (38.3%), headache (51.1%), dry eye (12.8%) with maximum subjects complaining of eye fatigue (59.6%) during the use of this device.

General specifications

The purpose of ophthalmic microscopes is to improve the surgeon's view. There are several designs of ophthalmic microscopes in the market, with different specifications. Some general specifications, which should be accurate enough, are cited below:

  • FIELD OF VIEW: while looking through the lens of a microscope a circular area is evident, its diameter is known as the field of view and should be at least 15mm to 50mm
  • ILLUMINATION SYSTEM: an ophthalmic microscope should be equipped with three types of illuminations —oblique illumination, combined focal and slit lamp illuminator, and coaxial illumination.
  • MAGNIFICATION: a practically objective lens of 150-200mm matched with eyepieces of 10x or 12.5x gives the best range of magnification.
  • DEPTH OF FIELD: it is the distance between the nearest and farthest object plane in a focused image. It grows thinner with increased magnification and vice versa.
  • WORKING LENGTH: this is the distance from the objective lens to the patient's eye. The ideal working distance is 150-200mm.
  • FOCAL LENGTH: for modern ophthalmic surgery, objective focal lengths of 150 mm, 175 mm, and 200 mm are commonly used. It is the distance between the objective lens and the object under focus.

How an ophthalmic microscope works

A surgeon gets a stereoscopic, high quality magnified and illuminated image of the surgical field while using a surgical or ophthalmic microscope. The optical part consists of a binocular head, a magnification changer, an objective lens, and an illuminator.

The binocular head consists of two telescopes and adjustable eyepieces. There is a knob in it to alter the magnification. The working distance depends on the focal length of the objective lens and the type of surgery—it is specific for each type of surgery. Focal lengths of 150 mm, 175 mm, and 200 mm are commonly used in ophthalmic surgeries that require subtlety.

The optical system is attached to the floor stand's suspension arm, which makes it possible to position the optics and fix them in place. The foot pedal controls all such functions like the focus, the zoom, the position of the optics over the eye to turn the illumination on and off.

The illumination system is usually kept on the floor stand to keep the bulb heat away from the operating field. The light is transmitted to the operating field using a fiber optic cable. The light in this ophthalmic instrument is usually coaxial to avoid shadows.

Market leaders

Some of the prominent players in the market of ophthalmic microscopes include:

CARL ZEISS MEDITEC AG

Carl Zeiss Meditec AG, Jena, Germany supply and provide:

  • innovative technologies and application-oriented solutions
  • complete packages of solutions for the diagnosis and treatment of ophthalmic diseases
  • innovative visualization solutions in the field of microsurgery

LEICA MICROSYSTEMS:

Optical microscopes, equipment for the preparation of microscopic specimens, and all other related products are manufactured as well as distributed by the Leica Microsystems GmbH.

OLYMPUS CORPORATION:

Olympus Corporation is a Japanese company that builds products of optics and reprography fields. Olympus also makes optical and digital microscope systems for life science solutions and is a leading supplier of such products.

HAAG-STREIT SURGICAL GMBH:

This company manufactures operating microscopes for ophthalmology, plastic & reconstructive surgery, neuro and spine surgery, and ENT applications of any kind. This shows the interest of this company in microsurgeries.

SYNAPTIVE MEDICAL:

Synaptive is a company of visionaries committed to delivering innovative and results-oriented products. They solve surgical, imaging, and data challenges.

ALCON, INC. (NOVARTIS)

Alcon is the largest eye care device company in the world. It provides a wide range of items within the field of eye care and ophthalmology surgery.

TOPCON CORPORATION:

Topcon Corporation is a Japan-based company that manufactures optical equipment for ophthalmology and surveying.

ARI MEDICAL TECHNOLOGY CO., LTD.

ARI Medical is another professional provider of medical equipment and related items, not only in China but also in the world.

Conclusion

The ophthalmic microscope has revolutionized the field of ophthalmology and helped ophthalmologists in making a fortune. Still, apart from all that, the most primary impact it had on medical science is that it made working on tiny structures very feasible and easy. An ophthalmologist who is efficient in working with this device has the power to return the people their sight. The ophthalmic microscope should always be a part of any ophthalmology clinic, for it can easily cure many eye problems. Be it retinal surgery or cataract surgery. An ophthalmologist can easily cure that condition with the help of this device and be an eye of the people struggling with their vision.

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