Ординатура / Офтальмология / Учебные материалы / Clinical Diagnosis and Management of ocular trauma

Fig. 50.10: Corneo-scleral scar involving iris and lens

Fig. 50.11: Complete cataract after perforating corneal injury with iris and lens capsule damage

Fig. 50.12: Eye globe atrophy

Ultraviolet Corneal Burns

INTRODUCTION

Ultraviolet corneal burns can be caused by the use of sunlamps or welding lamps without use of proper eye protection.

INVESTIGATIONS

Careful history and slit-lamp examination should be performed. Topically applied fliorescein can reveal punctuate corneal staining.

DIFFERENTIAL DIAGNOSIS

In ultraviolet corneal burns differential diagnosis should be performed with ocular surface inflammation, dry eye, chemical burns.

TREATMENT

Patients should be treated with antibiotics and ocular surface lubricants.

PROGNOSIS

The prognosis is usually favorable. Rehabilitation is usually achieved in 24 to 48 hours.

Chemical and Thermal Burns of

the Eye

INTRODUCTION

Burns of the eye are one of the most urgent ocular emergencies. The extent and severity of damage are determined by the nature and concentration of the chemical agent as well as the time of contact with the tissue.

The damage caused by acids is progressive but longs only within the first few hours. Their buffering with tissue proteins lead to the tendency of damage localization at the area of the contact with the agent.

Alkali can penetrate rapidly into the tissue. This effect is determined by their ability to damage cellular membrane lipids, causing disruption of cells and melting of tissue. Tissue penetration of alkali occurs quickly and their effect may lasts for days.

Exposure to flame rarely affects the cornea and eye globe, but more likely to cause the lid damage.

CLINICAL SIGNS AND SYMPTOMS

Patient complains on the severe pain and loss of vision. Main symptoms include: necrosis of the skin, lids

The examiner should be looking for the presence of ocular perforating injuries and intraocular foreign bodies. The nature of the chemical agent should be differentiated.

TREATMENT

The eye should be irrigated immediately after injury with minimum of 1.0 liter of water. The only very rare exception – is the chemicals that react violently with water. The use of the neutralizing agents is feasible in case they are available. Fornices of the conjunctival sac should be washed thoughtfully. The latter can require application of local anesthetic agents to prevent patient’s squeezing.

Alkaline materials penetrate more rapidly into the cornea and anterior chamber. That is why the results of alkali burns are more severe then those of burns caused by acids.

Moderate and severe chemical burns may lead to scarring of conjunctiva with symblepharon formation. Cataracts are common consequence of severe chemical burns, especially alkali. Alkali penetration into the anterior chamber and coagulation of the anterior chamber angle structures can result in glaucoma.

Skin scarring of the lids can cause cosmetic defects but also chronic epiphora, trichiasis, exposure keratitis, corneal opacification. Damage of the tear ducts and lacrimal glands may lead to severe dry eye.

Introduction

Ocular trauma throws up interesting and varied clinical situations, some of which really make us scratch our brains and make us wish we had something more than our regular instrumentation to deal with the problems at hand.

In this chapter we are going to discuss the management of some such peculiar situations as a result of ocular trauma, which we feel are either difficult or outrightly impossible to be tackled.

We are going to discuss the role of a new surgical instrument known as the Plasma Knife in the management of such problems.

While traditional definition of trauma brings to our mind, accidents involving injuries to the eyes, we strongly feel that iatrogenic reasons of ocular trauma cannot be evaded while discussing this subject. So badly operated eyes have also been included in this textbook of ocular trauma.

What is Plasma (Fugo) Knife?

Before we go any further with this chapter, it is imperative to understand the nature of the instrument that is going to be referred to most frequently during the course of this article, i.e., the Plasma Knife. Designed by Dr.Richard Fugo, in USA, this device has been tuned for ophthalmic use.

The plasma, which we refer to, is also known as the fourth state of matter. Plasma is distinctly different from, solids, liquids and gases. It is also the most abundant phase of matter in the universe as both stars and interstellar dust consist of plasma. Plasma is often referred to as ionized gas. This is similar to normal gas except that electrons have been stripped from their respective nucleons and float freely within the plasma. Plasma is electrically conductive and can be manipulated by magnetic fields.

Plasma can be found in a variety of everyday contexts, including plasma displays, fluorescent lamps, neon signs, plasma balls, photolithographic etching machines, flames, lightning, aurora borealis and more. The cutting abilities of plasma can be gauged from the fact that Plasma cutters are used in the industry for precision cutting of steel.

Fugo’s plasma knife is a surgical device that uses plasma (focused electromagnetic energy) to perform precision cutting of ocular tissues. In the Fugo’s plasma knife, the plasma generating engine has been bundled into a small unit, which creates enough energy to be safely used for ophthalmological applications.

Plasma generation is done in a filament fixed to a hand piece and connected to the plasma generating engine. The filament is barely thicker than a human hair (100 micron). The tip can be made in different lengths and can be bent as required. Only the extreme tip gets activated for cutting. An electronic charge pump causes the upper layer of atoms in the filament (about a micron deep) to transform from the solid state into the activated plasma state. A focused electromagnetic field is used to control, contour and shape these plasma particles into a plasma cloud around the filament. (Fugo, 1999).

The temperature at the tip as measured with a thermocouple is as high as 4500 degrees centigrade, though the amount of total heat produced is very little because the surface area of the plasma produced is very small. The atomic particles that make up this plasma cloud are in such a high state of agitation that they literally dissolve the molecular bonds of the material they come in contact with. The tiny filament doesn’t bend, even when cutting through something as strong as cow-hide, because it never touches the material. The plasma cloud dissociates the material faster than the hand can move the instrument. (Fugo, 1999).

Cutting with even the sharpest diamond knife needs at least some counter pressure but the plasma knife

Fig. 51.1A: Fugo’s plasma Knife Unit, including the console, activation footswitch and the handpiece

The Fugo’s plasma knife unit essentially consists of a console, a foot switch and a handpiece, to which disposable plasma delivery tips are attached. The machine runs on rechargeable batteries. A single charge delivers up to one hour of continuous plasma energy.

There are two setting switches on the machine. One knob adjusts between low medium and high energy while the other knob selects the intensity of cutting energy.

Fig. 51.1B: Low magnification picture of the Plasma knife tip attached to the hand piece with a bayonet mount

Fig. 51.1D: Activated plasma knife filament seen under magnification. The yellow part is the plasma and the orange part is the photon cloud.It is the plasma which cuts, not the photon cloud. If plasma is generated in a dark room,it emits bright flashes of light

An uncharged plasma blade filament has no cutting ability at all. It is the plasma that creates the incision. The inactivated tip has difficulty even in abrading corneal epithelium. (Fugo, 1999). The activated tip easily cuts through a 50 micron stainless steel wire.

The Fugo’s Plasma Knife has been approved by US FDA for performing capsulotomy and trans-ciliary filteration for glaucoma. Already things are underway for the introduction of this fundamental technology in general surgery and dentistry.

Key Properties of Plasma Knife

a.Cuts effortlessly.

b.There is no tissue drag.

c.Coagulates as it cuts.

d.Ease of use.

Fig. 51.2C: The plasma blade was activated and a round circle was traced in the optical axis in an effort to cut the dense membrane. You can very well visualize the process of cutting and the formation of cavitation bubbles in the figure above

Fig. 51.2A: A 22-year-old male patient suffered injury in a road accident 6 months ago. Left eye was lost and the right eye suffered bad injuries. Cornea had been repaired. The ruptured cataract had absorbed on its own, leaving behind a thick membrane in the pupil formed by the fusion of the anterior and the posterior capsule and imprisoned lens material. It was planned to clear the visual axis with the plasma knife and implant an Iris Claw Lens

Fig. 51.2D: The plasma knife membranectomy was completed with the cut out part of the membrane resting in the centre.This piece was removed with a forceps and limited anterior vitrectomy done

Fig. 51.2B: The plasma knife tip was introduced into the anterior chamber through a 2.8m keratome incision while a cannula was introduced from the left paracentecis to deliver continuous methyl cellulose irrigation

Fig. 51.2E: An Iris Claw Lens implant is fixed to the anterior surface of the iris

Fig. 51.2F: A 10-month post operative picture of the patient with corrected visual acuity of 6/18 Snellen’s. Patient had to wear high cylindrical glasses because of corneal scarring. As of now, the patient is mobile

Fig. 51.3A: Intraoperative picture of an encapsulated metallic foreign body in the retina.During the pre-operative evaluation, it was the B-scan and the CT scan which confirmed the presence of the foreign body cocooned inside the fibrous tissue.During vitrectomy the fibrosis was found to be so thick that it could not be split open with the tip of a vitrector or 24-gauge needle. We even tried using a diamond blade, mounted on a 20-gauge tip to cut the shell open but of no avail.So the services of the plasma knife were sought. The endo-laser marks can be seen applied to the retina all around the foreign body

Figs 51.3C to E: Showing the various stages of the exposure of the foreign body while the fibrotic tissue is being sliced with the plasma knife.There was no push generated by the plasma knife during the cutting of the fibrous tissue, unlike the needle and the diamond blade

Fig. 51.3B: A special plasma knife tip, long enough to reach the retinal surface was utilized to expose the hidden foreign body. You can see the tip of the foreign body getting progressively exposed

Fig. 51.3F: This is a picture of the extracted foreign body being held with an intraocular foreign body removal forceps, which will be removed via pars plana

Fig. 51.4A: A 9-year-old female child suffering from Iatrogenic trauma having been operated for congenital cataract 4 years ago.The parents were unaware whether lens implantation had been done or not. The pupil was slit like and closed off with a layer of pigment.Patient was taken up for exploratory surgery because of strongly positive perception and projection and a normal B-Scan ultrasound

Fig. 51.4B: Iris hooks were used to keep the pupil expanded after dissecting the adhesions of the posterior surface of the entire iris to the tissues below.Below the iris, we discover a intraocular lens encapsulated between a thick anterior and posterior capsule

Fig. 51.4D: A very thick membrane (posterior capsule) could be visualized very clearly under the intraocular lens.A gap was created between the posterior chamber intraocular Lens and the posterior capsule so that the plasma knife tip could be slipped into the gap

Fig. 51.4E: The plasma knife was pushed under the intraocular lens. It was then activated and a circle was traced on the fibrosed posterior capsule

Fig. 51.4C: The plasma knife was first used to cut the anterior capsule while the anterior chamber was continuously irrigated with methyl cellulose.The plasma knife tip was traced on the fibrotic anterior capsule and within no time the thick capsule was inundated

Fig. 51.4F: A perfect opening was created in the centre of the thick posterior capsule. The cut out piece of the posterior capsule was removed with a forceps and limited anterior vitrectomy was performed

Fig. 51.4G: Picture at the end of the procedure with a clear visually axis

Fig. 51.4H: A 4-month post-operative picture of the same eye showing a nicely created opening in the centre in the visual axis.The immediate visual result was poor because of amblyopia and pleoptics were started

Fig. 51.6A: Picture of a child’s eye aged 6, post penetrating ocular trauma, having been repaired elsewhere along with implantation of a posterior chamber lens. A thick vascularized membrane was visible in the pupil and the intraocular lens formed a part of this complicated mess. Perception and projection of light was strongly positive and B-Scan ultrasound revealed a clear posterior segment, therefore we decided to clear the visual axis

Fig. 51.6B: Since the implantation of the intraocular lens was far from satisfactory, it was decided to explant the lens after dissecting it carefully from its surrounding tissues. Plasma knife was then used to slice through the membrane after retracting the pupil. This one day post-operative picture of the patient after membranectomy along with limited anterior vitrectomy

Fig. 51.5: Picture of a posterior chamber IOL which went on to progress to optic capture into the pupil, cheese wiring of the haptics through the iris tissue and complete closure of the pupil with irido - capsular tissue. Vain attempts to clear the pupil with a yag laser are visible as pits on the optic of the lens. Since the tissues were strongly fused to each other, the plasma knife was used to cut through the stubborn tissue, which obliged by creating a round pupil in the middle. The rest of the abnormalities continue to exist but the patient can see now and has no other major problem

Fig. 51.6C: Two months’ post-operative picture of the same eye showing a clear visual axis

Fig. 51.7A: Intraoperative picture of an eye in an 11-year old child after blunt trauma with a fire cracker.There was mature traumatic cataract with fibrosed and thickened anterior capsule and traumatic mydriasis. We decided to do the capsulorrhexis with the plasma knife

Figs 51.7B and C: Pictures showing plasma knife capsulotomy in progress while the viscoelastic was being injected through the side port

Fig. 51.7D: Implantation of the intraocular lens into the capsular bag could be done. The capsulotomy performed within the fibrosed capsule is clearly visible. It seems that in the absence of the plasma knife, optimal surgical outcome may not have been possible

Fig. 51.8A: A typical case of blunt trauma with add on Iatrogenic ocular trauma in a 12-year-old girl operated for traumatic cataract and lens implantation elsewhere. The intraocular lens visible in the anterior chamber had seemingly migrated from the posterior chamber into the anterior chamber.While one haptic was still behind the iris, the optic was in front of the iris and the second haptic was seen missing, having broken off near the haptic-optic junction.Whether this was accidentally broken while implanting or deliberately done will never be known.In addition, there was an intimidating vascularized iridocapsular membrane in the pupillary area. Since B-Scan revealed a normal looking posterior segment and perception and projection of light was good,we decided to explant the lens and perform pupilloplasty

Figs 51.8B and C: After explantation of the broken intraocular lens, we tried to do pupilloplasty with a vitrectomy cutter as well as with a capsulotomy needle.Both of these instruments were not only ineffective but also led to bleeding from the tissues

Figs 51.8D and E: Then we pressed the plasma knife into service. A perfect pupilloplasty could be performed with the plasma knife with minimal bleeding and fuss.Limited anterior vitrectomy followed the pupilloplasty