Cyclodestruction or cycloablation is a surgical procedure done in management of

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

. Cyclodestruction reduce

intraocular pressure Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. Most tonometers are calibrated to ...

(IOP) of the eye by decreasing production of

aqueous humor The aqueous humour is a transparent water-like fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the posterior ...

by the destruction of

ciliary body The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliar ...

. Until the development of safer and less destructive techniques like micropulse diode cyclophotocoagulation and endocyclophotocoagulation, cyclodestructive surgeries were mainly done in refractory glaucoma, or advanced glaucomatous eyes with poor visual prognosis.

Types

Cyclodestruction may be done by using

diathermy Diathermy is electrically induced heat or the use of high-frequency electromagnetic currents as a form of physical therapy and in surgical procedures. The earliest observations on the reactions of high-frequency electromagnetic currents upon the ...

, penetrating cyclodiathermy,

cryotherapy Cryotherapy, sometimes known as cold therapy, is the local or general use of low temperatures in medical therapy. Cryotherapy may be used to treat a variety of tissue lesions. The most prominent use of the term refers to the surgical treatment, s ...

ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...

or by surgical excision.

Cyclophotocoagulation

Cyclophotocoagulation (CPC), the most common cyclodestructive procedure is done using laser beam of different wavelengths.

Ruby laser A ruby laser is a solid-state laser that uses a synthetic ruby crystal as its gain medium. The first working laser was a ruby laser made by Theodore H. "Ted" Maiman at Hughes Research Laboratories on May 16, 1960. Ruby lasers produce pulses of c ...

(693 nm wavelength), Nd:YAG laser (1064 nm wavelength) or

diode laser The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with e ...

(810 nm wavelength) can be used to perform CPC. Commomon cyclophotocoagulation techniques include transscleral cyclophotocoagulation (TS-CPC), continuous-wave diode cyclophotocoagulation (CW-TSCPC), MicroPulse diode cyclophotocoagulation (MP-TSCPC), endocyclophotocoagulation (ECP) and high-intensity focused ultrasound cyclodestruction (HIFU). Complications are lesser with Trans-scleral diode laser cyclophotocoagulation and Endoscopic diode laser cyclophotocoagulation.

Transscleral cyclophotocoagulation

Diode laser with a wavelength of 810 nm is used to perform trans-scleral cyclophotocoagulation. In TS-CPC, the laser absorbed by

melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...

of ciliary processes causes photocoagulation. Since it is a painful procedure, TS-CPC is usually performed under

retrobulbar A retrobulbar block is a regional anesthetic nerve block in the retrobulbar space, the area located behind the globe of the eye. Injection of local anesthetic into this space constitutes the retrobulbar block. This injection provides akinesia o ...

or peribulbar

anesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), ...

. Micropulse transscleral diode cyclophotocoagulation (MP-TSCPC), a modified TS-CPC procedure is a more safer procedure.

Endocyclophotocoagulation

Endocyclophotocoagulation (ECP) or endoscopic cyclophotocoagulation using an endoscope allows direct view of the ciliary processes during surgery. Compared to TS-CPC, tissue disruption is lesser with ECP.

Cyclocryotherapy

Cyclocryotherapy is done by freezing the

ciliary processes The ciliary processes are formed by the inward folding of the various layers of the choroid, viz. the choroid proper and the lamina basalis, and are received between corresponding foldings of the suspensory ligament of the lens. Anatomy The ...

of the eye. In

neovascular glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

, cyclocryotherapy is advices when medical control of IOP is not possible.

Complications

Inflammation,

retinal detachment Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blin ...

hypotony Ocular hypotony, or ocular hypotension, or shortly hypotony, is the medical condition in which intraocular pressure (IOP) of the eye is very low. Description Normal IOP ranges between 10–20 mm Hg. The eye is considered hypotonous if the IOP is � ...

phthisis bulbi Phthisis bulbi is a shrunken, non-functional eye. It may result from severe eye disease, inflammation or injury, or it may represent a complication of eye surgery. Treatment options include insertion of a prosthesis, which may be preceded by enu ...

and sympathetic ophthalmia are some common complications of cyclodestructive procedures. Since there is risk of inflammation which lead to hypotony and phthisis bulbi, cyclophotocoagulation must be done with extreme caution in uveitic glaucoma. Pain,

hyphema Hyphema is a condition that occurs when blood enters the front (anterior) chamber of the eye between the iris and the cornea. People usually first notice a loss of vision or decrease in vision. The eye may also appear to have a reddish tinge, o ...

and

iridocyclitis Uveitis () is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and i ...

are possible complications of TS-CPC. Fibrin exudates, hyphema, cystoid macular edema and loss of vision are possible complications of ECP.

History

The first surgical procedures to reduce intraocular pressure of the eye, by decreasing production of aqueous humor, by damaging the ciliary body by diathermy, penetrating cyclodiathermy or surgical excision was done in the early twentieth century. Cyclodestruction by diathermy was first performed by Weve in 1933. In 1949, Berens et al. described cyclo-electrolysis. Cyclocryotherapy was first described by Bietti in 1950. Cyclodestruction by cyclophotocoagulation was first performed by Beckman et al., in 1972, using a ruby laser. ECP was developed by Martin Uram in 1992.

References

{{Reflist Laser medicine Glaucoma Eye surgery