Eye surgery

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Eye surgery, also known as ophthalmic surgery or ocular surgery, is a surgical procedure performed on the eye or its adnexa typically by an ophthalmologist<ref>Surgery Encyclopedia - Ophthalmologic surgery</ref>

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Laser surgery and incisional surgery

Although the terms "laser eye surgery" and "refractive surgery" are commonly used as if they were interchangeable, this is not the case. Lasers may be used to treat nonrefractive conditions (e.g. to seal a retinal tear), while radial keratotomy is an example of refractive surgery without the use of a laser.

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Types of eye surgeries

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Cataract surgery

Template:Main A cataract is an opacification or cloudiness of the eye's crystalline lens due to aging, disease, or trauma that typically prevents light from forming a clear image on the retina. If visual loss is significant, surgical removal of the lens may be warranted, with lost optical power usually replaced with a plastic intraocular lens (IOL). Due to the high prevalence of cataracts, cataract extraction is the most common eye surgery<ref>Uhr, Barry W. History of ophthalmology at Baylor University Medical Center. Proc (Bayl Univ Med Cent). 2003 October; 16(4): 435–438. PMID 16278761</ref>. The two main types of cataract extraction are intracapsular cataract extraction (ICCE) and extracapsular cataract extraction (ECCE).

Intracapsular cataract extraction involves the removal of the lens and the surrounding lens capsule in one piece. The procedure has a relatively high rate of complications due to the large incision required and pressure placed on the vitreous body, thus is rarely performed in countries where operating microscopes and high-technology equipment are readily available<ref>Surgery Encyclopedia - Extracapsular cataract extraction</ref>. Cryoextraction is a form of ICCE that freezes the lens with a cryogenic substance such as liquid nitrogen<ref>Surgery Encyclopedia - Cryotherapy for cataracts</ref>. Although it is now used primarily for the removal of subluxated lenses, it was the favored form of cataract extraction from the late 1960s to the early 1980s<ref>Meadow, Norman B. Cryotherapy: A fall from grace, but not a crash. Ophthalmology Times. October, 15, 2005.</ref>.

Extracapsular cataract extraction involves the removal of the lens while the elastic lens capsule is left partially intact to allow implantation of an intraocular lens<ref>Surgery Encyclopedia - Extracapsular cataract extraction</ref>. There are two main types of extracapsular surgery: conventional ECCE and phacoemulsification. Conventional extracapsular cataract extraction involves manual expression of the lens through an incision made in the cornea or sclera. Although it requires a larger incision and the use of stitches, the conventional method is indicated for patients with very hard cataracts or weak corneal epithelial tissue. Phacoemulsification involves the use of an ultrasonic vibrating handpiece to shatter and break up a cataract, thus making it easier to remove. Because a smaller incision is required, few or no stitches are needed and the patient's recovery time is usually shorter<ref>Surgery Encyclopedia - Phacoemulsification for cataracts</ref><ref>Surgery Encyclopedia - Extracapsular cataract extraction</ref>.

A capsulotomy is a procedure to open a portion of the lens capsule. An anterior capsulotomy refers to the opening of the front portion of the lens capsule, whereas a posterior capsulotomy refers to the opening of the back portion of the lens capsule. In an extracapsular surgery, the surgeon performs an anterior capsulotomy, or capsulorhexis, to create an opening through which the lens nucleus can be removed and the intraocular lens implant inserted. An opacification or clouding of the posterior lens capsule frequently occurs in those who have had an extracapsular cataract extraction procedure, therefore, a laser posterior capsulotomy, or YAG laser capsulotomy, is used to clear the back implant surface <ref>Surgery Encyclopedia - Laser posterior capsulotomy</ref>. (Whereas a capsulotomy is the creation of an opening in the lens capsule, a capsulectomy is the acutal removal of lens capsule tissue.)

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Glaucoma surgery

Glaucoma is a group of diseases affecting the optic nerve that results in vision loss and is frequently characterized by raised intraocular pressure (IOP). There are many glaucoma surgeries, and variations or combinations of those surgeries, that facilitate the escape of excess aqueous humor from the eye to lower intraocular pressure, and a few that lower IOP by decreasing the production of aqueous.

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Procedures that facilitate outflow of aqueous humor

Laser trabeculoplasty

A trabeculoplasty is a modification of the trabecular meshwork. Laser trabeculoplasty (LTP) is the application of a laser beam to burn areas of the trabecular meshwork, located near the base of the iris, to increase fluid outflow. LTP is used in the treatment of various open-angle glaucomas <ref>University of Michigan Health System - Surgery for Glaucoma</ref>. The two types of laser trabeculoplasty are argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT). As its name suggests, argon laser trabeculoplasty uses an argon laser to create tiny burns on the trabecular meshwork<ref>EyeMDLink.com - Argon Laser Trabeculoplasty (ALT)</ref>Selective laser trabeculoplasty is newer technology that uses a Nd:YAG laser to target specific cells within the trabecular meshwork and create less thermal damage than ALT<ref>Review of Optometry - SLT: The Laser Picks Up Where Medications Leave Off</ref> <ref>Glaucoma Research Foundation - SLT: A New Type of Glaucoma Surgery</ref>.

Iridotomy

An iridotomy involves making puncture-like openings through the iris without the removal of iris tissue. Performed either with standard surgical instruments or a laser, it is typically used to decrease intraocular pressure in patients with angle-closure glaucoma. A laser peripheral iridotomy (LPI) is the application of a laser beam to selectively burn a hold through the iris near its base. LPI may be performed with either an argon laser or Nd:YAG laser<ref>Surgery Encyclopedia - Laser iridotomy</ref> <ref>EyeMDLink.com - Laser Peripheral Iridotomy (PI)</ref>.

Iridectomy

An iridectomy, or surgical iridectomy, involves the removal of a portion of iris tissue<ref>Surgery Encyclopedia - Iridectomy</ref>. A basal iridectomy is the removal of iris tissue from the far periphery, near the iris root; a peripheral iridectomy is the removal of iris tissue at the periphery; and a sector iridectomy is the removal of a wedge-shaped section of iris that extends from the pupil margin to the iris root, leaving a keyhole-shaped pupil.

Filtering procedures: penetrating vs. non-penetrating

Filtering surgeries are the mainstay of surgical treatment to control intraocular pressure<ref>Jacobi PC, Dietlein TS, Krieglstein GK. "Technique of goniocurettage: a potential treatment for advanced chronic open angle glaucoma." Br J Ophthalmol. 1997 Apr;81(4):302-7. PMID 9215060.</ref>. An anterior sclerotomy or sclerostomy is used to gain access to the inner layers of the eye [1] [2] [3] in order to create a drainage channel from the anterior chamber to the external surface of the eye under the conjunctiva, allowing aqueous to seep into a bleb from which it is slowly absorbed. Filtering procedures are typically divided into either penetrating or non-penetrating types depending upon whether an intraoperative entry into the anterior chamber occurs [4] [5].

Penetrating filtering surgeries are further subdivided into guarded filtering procedures, also known as protected, subscleral, or partial thickness filtering procedures (in which the surgeon sutures a scleral flap over the sclerostomy site [6]), and full thickness procedures [7]. Trabeculectomy is a guarded filtering procedure that removes of part of the trabecular meshwork Template:Ref [8]. Full thickness procedures include sclerectomy, posterior lip sclerectomy (in which the surgeon completely excises the sclera on the area of the sclerostomy [9]), trephination, thermal sclerostomy (Scheie procedure), iridenclesis, and sclerostomy (including conventional sclerostomy and enzymatic sclerostomy) [10] [11].

Non-penetrating filtering surgeries do not penetrate or enter the eye's anterior chamber [12] [13]. There are two types of non-penetrating surgeris: Bleb-forming and viscocanalostomy [14] [15]. Bleb forming procedures include ab externo trabeculectomy and deep sclerectomy[16]. Ab externo trabeculectomy (AET) involves cutting from outside the eye inward to reach Schlemm's canal, the trabecular meshwork, and the anterior chamber. Also known as non-penetrating trabeculectomy (NPT), it is an ab externo (from the outside), major ocular procedure in which Schlemm's canal is surgically exposed by making a large and very deep scleral flap. The inner wall of Schlemm's canal is stripped off after surgically exposing the canal [17]. Deep sclerectomy, also known as nonpenetrating deep sclerectomy (PDS) or nonpenetrating trabeculectomy is a filtering surgery where the internal wall of Schlemm's canal is excised, allowing subconjunctival filtration without actually entering the anterior chamber [18]; it is commonly performed with the Aquaflow® collagen wick [19]. Viscocanalostomy is also an ab externo, major ocular procedure in which Schlemm's canal is surgically exposed by making a large and very deep scleral flap. In the VC procedure, Schlemm's canal is cannulated and viscoelastic substance injected (which dilates Schlemm's canal and the aqueous collector channels)[20].

Other surgical procedures

Goniotomy and trabeculotomy are similar simple and directed techniques of microsurgical dissection with mechanical disruption of the trabecular meshwork [21] [22] [23]. Gonotomy procedures include surgical goniotomy and laser goniotomy. A surgical goniotomy involves cutting the fibers of the trabecular meshwork to allow aqueous fluid to flow more freely from the eye [24][25]Template:Ref. Laser goniotomy is also known as goniophotoablation and laser trabecular ablation [26]. In many patients suffering from congenital glaucoma, the cornea is not clear enough to visualize the anterior chamber angle. Although an endoscopic goniotomy, which employs an endoscope to view the anterior chamber angle, may be performed [27], a trabeculotomy which accesses the angle from the exterior surface of the eye, thereby eliminating the need for a clear cornea, is usually preferred in these instances. A specially designed probe is used to tear through the trabecular meshwork to open it and allow fluid flow [28].Video

Tube-shunt surgery or drainage implant surgery involves the placement of a tube to facilitate aqueous outflow from the anterior chamber Template:Ref [29][30]. Trabeculopuncture uses a Q switched Nd:YAG laser to punch small holes in the trabecular meshwork with [31][32] [33]. Goniocurretage is an "ab interno" (from the inside) procedure that used an instrument "to scrape pathologically altered trabecular meshwork off the scleral sulcus" [34][35] [36]. A surgical cyclodialysis is a rarely used procedure that aims to separate the ciliary body from the sclera.

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Procedures that decrease production of aqueous humor

Certain cells within the eye's ciliary body produce aqueous humor. A ciliary destructive or cyclodestructive procedure is one that aims to destroy those cells in order to reduce intraocular pressure [37]. Cyclocryotherapy, or cyclocryopexy, uses a freezing probe [38]. Cyclophotocoagulation, also known as transscleral cyclophotocoagulation, ciliary body ablation,[39], cyclophotoablation [40], and cyclophototherapy [41], uses a laser.Template:RefTemplate:Ref.

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Refractive surgery

Template:Main

  • Refractive surgery aims to correct errors of refraction in the eye, reducing or eliminating the need for corrective lenses
    • Keratomilleusis is method of reshaping the cornea surface to change its optical power. A disc of cornea is shaved off, quickly frozen, lathe-ground, then returned to its original power.
    • Automated lamellar keratoplasty (ALK)
    • Laser assisted in-situ keratomileusis (LASIK) Template:Ref
    • Laser assisted sub-epithelial keratomileusis (LASEK), aka Epi-LASIK
    • Photorefractive keratectomy (PRK) Template:Ref
    • Laser thermal keratoplasty (LTK)
    • Conductive keratoplasty (CK) uses radio frequency waves to shrink corneal collagen. It is used to treat mild to moderate hyperopia. Template:Ref
    • Limbal relaxing incisions (LRI)
    • Astigmatic keratotomy (AK), aka Arcuate keratotomy or Transverse keratotomy
    • Radial keratotomy (RK)
    • Hexagonal keratotomy (HK)
    • Epikeratophakia is the removal of the corneal epithelium and replacement with a lathe cut corneal button Template:Ref.
    • Intracorneal rings (ICRs), or corneal ring segments (Intacs) [42]
    • Implantable contact lenses
  • Presbyopia reversal
    • Anterior ciliary sclerotomy (ACS)
      • Laser reversal of presbyopia (LRP)
    • Scleral expansion bands
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Corneal surgery

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Vitreo-retinal surgery

  • Vitreo-retinal surgery includes the following
    • Vitrectomy [43]
      • Anterior vitrectomy is the removal of the front portio of vitreous tissue. It is used for preventing or treating vitreous loss during cataract or corneal surgery, or to remove misplaced vitreous in conditions such as aphakia pupillary block glaucoma.
      • Pars plana vitrectomy (PPV), or trans pars plana vitrectomy (TPPV), is a procedure to remove vitreous opacities and membranes through a pars plana incision. It is frequently combined with other intraocular procedures for the treatment of giant retinal tears, tractional retinal detachments, and posterior vitreous detachments [44].
    • Pan retinal photocoagulation (PRP) is a type of photocoagulation therapy used in the treatment of diabetic retinopathy Template:Ref.
    • Retinal detachment repair
      • A scleral buckle is used in the repair of a retinal detachment to indent or "buckle" the sclera inward, usually by sewing a piece of preserved sclera or silicone rubber to its surface Template:Ref.
      • Laser photocoagulation, or photocoagulation therapy, is the use of a laser to seal a retinal tear Template:Ref.
      • Pneumatic retinopexy
      • Retinal cryopexy, or retinal cryotherapy, is a procedure that uses intense cold to induce a chorioretinal scar and to destroy retinal or choroidal tissue Template:Ref.
    • Macular hole repair
    • Partial lamellar sclerouvectomyTemplate:Ref
      • Partial lamellar sclerocyclochoroidectomy
      • Partial lamellar sclerochoroidectomy
    • Posterior sclerotomy is an opening made into the vitreous through the sclera, as for detached retina or the removal of a foreign body [45].
  • Radial optic neurotomy

macular translocation surgery 

 thru 360 degree retinotomy
 thru scleral imbrication technique
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Eye muscle surgery

With approximately 1.2 million procedures each year, extraocular muscle surgery is the third most common eye surgery in the United States [46].

  • Eye muscle surgeries typically correct strabismus and include the following Template:Ref [47]:
    • Loosening / weakening procedures
      • Recession involves moving the insertion of a muscle posteriorly towards its origin.
      • Myectomy
      • Myotomy
      • Tenectomy
      • Tenotomy
    • Tightening / strengthening procedures
      • Resection
      • Tucking
      • Advancement is the movement of an eye muscle from its original place of attachment on the eyeball to a more forward position.
    • Transposition / repositioning procedures
    • Adjustable suture surgery is a method of reattaching an extraocular muscle by means of a stitch that can be shortened or lengthened within the first post-operative day, to obtain better ocular alignment [48].
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Oculoplastic surgery

  • Oculoplastic surgery, or oculoplastics, is the subspecialty of ophthalmology that deals with the reconstruction of the eye and associated structures.
    • Browplasty [49]
    • Eyelid surgery [50]
    • Eye removal
      • Enucleation is the removal of the eye leaving the eye muscles and remaining orbital contents intact Template:Ref.
      • Evisceration is the removal of the eye's contents, leaving the scleral shell intact. Usually performed to reduce pain in a blind eye.
      • Exenteration is the removal of the entire orbital contents, including the eye, extraocular muscles, fat, and connective tissues; usually for malignant orbital tumors Template:Ref.
    • Dacryocystorhinostomy (DCR)[51]
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Notes

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References

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See also

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External links

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