Cyclodestruction or cycloablation is a surgical procedure done in management of

glaucoma Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of ...

. Cyclodestruction reduces

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 t ...

(IOP) of the eye by decreasing production of

aqueous humor The aqueous humour is a transparent water-like fluid similar to blood 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 po ...

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 ciliary ...

. 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 the human organism to high-frequency electromagn ...

, penetrating cyclodiathermy,

cryotherapy Cryotherapy, sometimes known as cold therapy, is the local or general use of low temperatures in medical therapy. Cryotherapy can be used in many ways, including whole body exposure for therapeutic health benefits or may be used locally to treat ...

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

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'' originated as an acronym for light amplification by stimulated emission of radi ...

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 ...

(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 semiconductor laser or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode p ...

(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 (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes. There are ...

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

anesthesia Anesthesia (American English) or anaesthesia (British English) 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 prev ...

. 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 In the anatomy of the eye, 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 ligam ...

of the eye. In

neovascular glaucoma Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of ...

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

Complications

Inflammation,

retinal detachment Retinal detachment is a condition where the retina pulls away from the tissue underneath it. It may start in a small area, but without quick treatment, it can spread across the entire retina, leading to serious vision loss and possibly blindness. ...

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 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 the medical condition of bleeding in the anterior chamber of the eye between the iris and the cornea. People usually first notice a loss or decrease in vision. The eye may also appear to have a reddish tinge, or it may appear as a s ...

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

{{Eye procedures Laser medicine Glaucoma Eye surgery