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

Introduction

Refractive surgeries gained momentum from 1960’s with inception of RK followed a decade later by evolution of excimer laser and PRK, had a crescendo in 1990’s with Lasik gaining footage and the revolution has been ever on with increasing vigor and growing understanding.

On an average, over 17 million have undergone LASIK so far. More than 2 million LASIK procedures have been performed each year. Over 22 % with a refractive error of –5 D to – 7 D have undergone LASIK in US. A further revelation tells us that 19 % of the US refractive surgeons have themselves undergone refractive surgery.

If one reflects on the popularity and demand of a surgical procedure on the human body, refractive procedures claim the 2nd position, next only to cataract surgery.

The primary concerns which needs reflection is occurrence of trauma of the refractive surgery per se and trauma after refractive surgery.

Trauma in LASIK could range from flap related complications, rare instances of corneal perforations, corneal infection, macular hemorrhage, interface deposits, epithelial ingrowth and irregular astigmatism. The increasing concern following LASIK is that the force that the residual untreated cornea could resist decreases as a result of a thinner stromal bed and can lead to Iatrogenic Keratectasia. Trauma from RK could range from perforation to residual refractive error, would response unpredictability, hyperopic shifts, starburst phenomenon and drop in BCVA. PRK could complicate issues with its varying wound response trends with incremental need for topical steroids, residual nebular haze, residual refractive error, etc.

But the burgeoning problem is the propensity of late onset trauma impact in any of these eyes and the risk: benefit ratio.

If we look at the profile of refractive surgery patients, it’s largely a young, active and working population in the prime of their productive life.

US Eye Injury Registry in 19991 assessed closed Vs open globe injury in 173 patients who had undergone refractive surgery prior to injury. 165 of these eyes developed traumatic wound dehiscence. Only 20.6 % recovered 20/200 or better vision. The primary concern which arises from this study data is the effect of trauma on ocular integrity. The other possibility is the probability of closed globe injury getting converted to an open globe injury, in a setting of post-refractive surgery.

Trauma in Radial Keratotomy

Radial keratotomy (Fig. 42.1) was introduced in 60’s and 70’s. It maintained its stand as a popular refractive procedure till 90’s.

Cassey et al 2 came up with the analysis of the tensile strength of corneal wounds. The conclusion derived was that the weakest point in the eye in a post incisional surgery is the site of incision. After complete healing, the tensile strength is only 50% of normal.

Fig. 42.1: Radial keratotomy

Pin heiro et al3 further assessed corneal integrity after refractive surgery. The analysis indicated that following blunt injury in a normal eye, rupture

Trauma in PRK

Burnstein et al report8 on PRK ablations in human cadaver eyes indicate that these eyes following PRK ablations of – 6.00 to –54 D were infused with nitrogen gas to build high pressure in the eye and the ablation zones responded to pressure trauma only after a

Trauma to LASIK Flap

Early flap complications occur in the first 24 hours. The sequence of events declines after one week. The flap slippage and displacement most commonly occur in the early postoperative period and presumably as a result of mechanical disruption such as forceful blinking, lid squeezing and eye rubbing (Fig. 42.4).

Fig. 42.3: Enhancement 5 years after LASIK

Fig. 42.4: Flap dislocation within 24 hours

Fig. 42.5: DLK after foreign body removal

A mere foreign body removal with a spud or a needle on a LASIK flap acts like a shearing force, could cause flap slippage or DLK (Fig. 42.5). Recent or late dislocation of flap demand immediate attention

(Fig. 42.6).

Fig. 42.6: Late flap dislocation

The longer the time interval between occurrence and intervention, probability of intractable micro and macro striae (Fig. 42.7) drop in BCVA, irregular astigmatism and even onset of DLK is likely.

Fig. 42.7: Macro striae in post-LASIK trauma

These flaps need to be lifted, both surfaces of the flap hydrated thoroughly, stretched to the gutter and ironed out in a direction perpendicular to the direction of the striae. The interface also needs to be thoroughly irrigated and if in an eventuality of a long wait to intervention, possibility of epithelial ingrowth increases and appropriate debridement is indicated. Recalcitrant macrostriae demand removal of the overlying epithelium, hydrate, stretch and ironing of the flap. Lin et al report11 on complications with lamellar refractive surgery indicates flap adhesion and bonding occurs between 5 to 100 days with peak strength between ¼ and ½ of the original strength.

Reports of late flap complications following LASIK has been reported from 10 days to 5 years - playing

Fig. 42.8: Diffuse lamellar keratitis

Trauma in Surface Treatments

Surface ablations are by and large more risk free related to trauma although the refractive outcomes would be compromised without adequate wound modulators. The absence of the thick flap created in LASIK makes surface treatment more bio-mechanically stable and makes it less vulnerable to trauma.

Trauma in Phakic IOL Implants

Iris supported Phakic IOLs have multiple reports of disenclavation of haptics and decentration of phakic IOL (Fig. 42.9) which could lead to progressive endothelial loss if immediate intervention is not forth coming.

Conclusion

The conclusive ideas which emerge from this chapter is that one needs to practice abundant caution. Wearing shatter proof protective glasses is a necessary precaution. Literature reports are few, clinical experience rare but awareness of such occurrences and educating our patients would be preventive at large.

Fig. 42.9: Phakic IOL disenclavated after trauma

References

1.US Eye Injury Registry in 1999.

2.A. R. Gasset; C. H. Dohlman The tensile strength of corneal wounds. Arch Ophthalmol 1968;79:595-602.

3.MN Pinheiro, MR Bryant, R Tayyanipour. Corneal integrity after refractive surgery: effects of radial keratomy and mini-radial keratotomy Ophthalmology 1995; 102:297-301.

4.Casebeer JC, Shapiro DR , Phillips S. Severe ocular trauma without corneal rupture after radial keratotomy: case reports. J Refract Corneal Surg 1994; Jan-Feb: 10 (1): 31-33.

5.Pinheiro MN , Bryant MR, Tayyanipour R et al. Corneal integrity after refractive surgery. Effects of radial keratotomy and mini-radial keratotomy. Ophthalmology 1995 Feb; 102 (2): 297-301.

6.McKnight SJ, Fitz J, Giangiacomo J.et al .Report on corneal rupture following RK. Ophthalmic Surgery 1988; 19:165-67.

7.Peacock LW, Slade SG, Martiz J, et al. Ocular integrity after refractive procedures Ophthalmology 1997;104: 1079-83.

8.Burnstein Y, Klapper D, Hersh PS Experimental globe rupture after excimer laser photorefractive keratectomy. Arch ophthalmol 1995;113:1056-59.

9.Sun CC, Chang SW, Tsai RF. Traumatic Corneal Perforation With Epithelial Ingrowth After Laser In Situ Keratomileusis. Arch Ophthalmol 2001;119:907-09.

10.Cda RP, Narvaez J, King JA, et al. Late-onset traumatic dislocation with central tissue loss of laser in situ keratomileusis flap. Cornea 2006 Oct;25(9):1107-10.

11.Lin RT, Maloney RK. Flap complications associated with lamellar refractive surgery Am. J Ophthalmology 1999; 127:129-136.

Introduction

The implantations of IOLs in the phakic eye (phakic IOLs) is a relatively old technique to correct ametropia, they have been used in clinical practice in refractive surgery for 15 years.

The early problems are related to the design of the lens and the meticulous details of surgery. The late postoperative complications are related to the interaction of the IOL and the intimate ocular tissues during the lifetime of the patient. Lifelong, regular follow-up care is essential in all cases.

Explantation of the lens may ameliorate some of the complications. Later in life, if the patient develops a cataract, it should be possible to do an atraumatic explantation, followed by cataract extraction and implantation of another appropriate IOL. Development of a newer, safer technology to correct ametropia may necessitate explantation of the IOL.

However, the presence of the IOL inside the eye has been associated with complications specific to the type of phakic IOLs involved. Some of these complications have led to changes in design of some lenses and to discontinuing of others.9

Currently, only a few long-term studies are available with phakic IOLs the complication spectrum appear slowly and some lenses become forbidden to insert in some European country.8

We will describe the most frequent late complications and traumatisme associated with implantation of phakic IOLs.

Fig. 43.1: Eye care IOL (corneal)

preoperative examination should exclude those patients with low endothelial cell count or those with shallow anterior chambers because the risk of cell loss increases as the distance between phakic IOL and the endothelium decreases.

We know today that a minimum of 1.5 mm between the IOL and the corneal endothelium is needed to long-term safety. This explains the damage to the endothelium, if not explanted early to endothelial decompensation.3,11,12

Meticulous long-term follow-up of each patient is at the moment necessary for any AC phakic IOL to detect those individuals with significant damage to the endothelium and to explant the phakic IOL before clinically necessary.

Anterior Chamber Phakic IOLs (Fig. 43.1)

ENDOTHELIAL COMPLICATIONS AND ANTERIOR CHAMBER DEPTH

The main concern about AC Phakic IOLs is loss or damage to the endothelial integrity. An Exact

PIGMENT DISPERSION AND LENS DEPOSITS

Although no definite incidence for these conditions is reported in the literature, these conditions are seen in clinical practice. They normally do not negatively affect visual acuity and thus no futher procedure— except for regular clinical observation—is necessary.

This is now possible with the visante OCT (Carl Zeiss Meditec) or with the Pentacam (Oculus AG) which give you the exact morphology and sizing of the anterior chamber (Figs 43.3 and 43.4).

If an anterior chamber angle-supported phakic IOL is too short, the IOL will rotate in the anterior chamber causing important glare. Rotation of the anglesupported phakic IOLs might occur due to undersizing. In fact, 80% of eyes showed rotation greater than 15 degrees.8

A more frequent and serious complication is the pupil ovalisation. Ovalization of the pupil is a specific complication of angle-AC phakic IOLs. The position of haptics in the sclerocorneal angle and their size might lead to mild deformation of the iridosclerocorneal architecture, resulting in iris retraction and pupil ovalization.

Pupil distortion starts after 12 to 18 months of implantation, the pupil showing ovalisation, the longer axis being always the axis of the IOL.

Iris retraction with oval pupil deformation remains a concern of the angle-supported phakic IOLs. This mater together with potential damage to endothelial cells, is the major objection against the current lens designs (Figs 43.5 and 43.6).

Fig. 43.5: Anterior chamber Phakic IOL NuVita Bausch and Lomb Permanent mydriasis

INDUCED ASTIGMATISM

Surgically induced astigmatism is of significance because patients request acceptable unaided postoperative visual acuity.

GLAREAND HALOS

One disadvantage of AC phakic IOLs is that they are positioned in front of the pupil, with edge affects as

Fig. 43.6: Pupillary bloc with anterior phakic IOL

a potential source of optical aberrations. Furthermore, the relatioin of pupil size and center to the optic of the lens is a crucial factor that should be evaluated and discusses preoperatively.

GLAUCOMA

The risk of acute angle glaucoma is well known from aphakic anterior chamber IOLs therefore a peripheral iridectomy is recommended for this IOL.

CATARACT FORMATION

As the AC phakic IOL is positioned away from the lens, cataract formation is of less significance when compared to posterior chamber phakic IOLs.

Iris-fixated Anterior Chamber Phakic Intraocular Lenses

(Fig. 43.7)

The iris-fixated IOL is marketed in Europe as the Artisan has been used since 1978 for pseudophakic IOLs, mainly for secondary implantation in aphakic eyes. Since 1986, the Worst-Fechner IOL has been implanted in phakic eyes for the correction of high myopia and subsequently hyperopia. The original design was modified in 1991 to assure a sufficient vault between the IOL optic and the iris.

COMPLICATIONS OF IRIS-SUPPORTED PHAKIC IOLS5

One frequent complication is the loosing of the IOL from the iris. This can occur spontaneously or after

Fig. 43.7: Iris fixated lens: iris claw

Fig. 43.8: Decentration of the lens with not enough iris tissue grasp: Iris claw Artisan

Fig. 43.9: Iris claw Artisan, decentration

minor trauma. However, this complication is always the consequence of the so called “weak grasp”, that is insufficient amount iris tissue grasped in the claw

(Figs 43.8 and 43.9).

We will related an eye trauma with an artisan which induce a intumescent cataract, retinal detachcment and loss of vision.

There are in fact very few complications related to Artisan/Artiflex.

CHRONIC INFLAMMATION AND UVEITIS

The possiblility of chronic inflammation has always been a major concern with the iris-claw lens, as this IOL is fixated directly in the iris tissue and causes pressure or shear forces when the eye is moving.

Careful postoperative monitoring of inflammatory signs is necessary. If persistent intraocular inflammation occurs that is not sufficiently treatable with drugs, the removal of the implant must be considered.

PUPIL OVALIZATION AND DECENTRATION

Pupil ovalization or irregularity can occur if the fixation of the haptics is perfomed asymmetrically. No pregressive pupil ovalization has been reported so far.

This can lead to difficulties if the pupil itself is decentered and if the optical axis is not in the middle of the pupil. Postoperative decentration is possible if the enclavation is not sufficient.

Postoperativedislocationsduetobluntoculartrauma have been described. In the author’s experience, they observed only case of possible phakic IOL dislocation in a patient with very thin iris tissue (Fig. 43.10).

Fig. 43.10: Dislocated iris claw

CATARACT FORMATION

Cataract formation due to the iris-claw lens is very unlikely with myopic eye because it is inserted over a miotic pupil without contacting the crystalline lens.

Cataract formation has been reported in association with the iris-claw lens and hypermetropia on a longterm basis.

The increasing size of the crystalline lens with age and the formation of cataract, especially of an intumescent type, will greatly disturb the tissue relations. An early management of cataract, including the explantation of the implanted phakic lens, will be needed.

Implantation of a phakic lens in a hyperopic eye ought to be a small event for the operated eye; unfortunately, it is not so. Therefore, lifelong regular follow-up care is essential.

CASE REPORT (FIGS 43.11 AND 43.12)

A 41-year-old worker presented with a sudden loss of vision in the left eye after trauma. He reportedly had receive a cable on his left eye.

The patient had had uneventful bilateral implantation of Artisan toric phakic IOLs 1 year earlier to correct RE S-19.5 C -2.5 respectively LE S-14.0 C-3.0 the vision after one week was VAWC 0.5/0.6 On presentation at the emergency room, the left eye visus light perception. The globe presented no open wound. Anterior chamber had an hyphema, The Artisan phakic IOL were not found on examination. An intumescent white cataract with ruptured capsule and 180 degrees zonulolyse prolapsed inside the AC. No vitreous prolapse in AC. Eye pressure on the left

eye was 38 mm Hg.

On the echo B the retina seem on place and the iris-claw lens seem on the retina.