Malignant glaucoma as a complication of intravitreal triamcinolone acetonide

Aqueous misdirection after Nd:YAG goniopuncture in deep sclerectomy treated with Nd:YAG irido-zonulo-hyaloidotomy

BACKGROUND

To report a case of aqueous misdirection after goniopuncture in deep sclerectomy treated with Nd:YAG laser irido-zonulo-hyaloidotomy.

CASE PRESENTATION

About 72 years old patient with pseudoexfoliation glaucoma who underwent deep sclerectomy, developed aqueous misdirection after Nd:YAG laser goniopuncture. Medical management failed and subsequent peripheral Yag laser iridotomy to expose the zonules coupled with laser zonulo-hyaloidotomy was done and an instant gush of aqueous and vitreous substance prolapse through the iridotomy was noticed. Later, the anterior chamber was deep and the pressure was controlled.

CONCLUSIONS

Aqueous misdirection can occur after Nd:YAG laser goniopuncture. Nd:YAG laser irido-zonulo-hyaloidotomy can be effective in breaking the attack.

Clinical Management of Malignant Glaucoma

Malignant glaucoma remains one of the most challenging complications of ocular surgery. Although it has been reported to occur spontaneously or after any ophthalmic procedure, it is most commonly encountered after glaucoma surgery in eyes with prior chronic angle closure. The clinical diagnosis is made in the setting of a patent peripheral iridotomy and axial flattening of the anterior chamber. Intraocular pressure is usually elevated, but it may be normal in some cases. Although the exact etiology of this condition is not fully understood, several mechanisms have been proposed and it is thought to result from posterior misdirection of aqueous humor into or behind the vitreous. This review discusses pathophysiology, differential diagnosis, imaging modalities, and current treatment strategies for this rare form of secondary glaucoma.

Current concepts in the treatment of vitreous block, also known as aqueous misdirection

Vitreous block (VB), a rare secondary angle-closure caused by anterior rotation of the ciliary body, occurs in a variety of settings, but most frequently after glaucoma filtering surgery. The etiology remains unclear, but choroidal expansion and anterior vitreous abnormalities have been proposed. In the past, treatment of VB has yielded high rates of failure and recurrence. Advancements in surgical techniques, however, have led to improved visual outcomes. We review the history of this condition and present a stepwise approach to its diagnosis and treatment using modern imaging modalities and surgical techniques.

Spontaneous simultaneous bilateral malignant glaucoma of a patient with no antecedent history of medical or surgical eye diseases

PURPOSE

Malignant glaucoma, or aqueous misdirection syndrome, is a condition characterized by sudden intraocular pressure (IOP) elevation, and it is usually unilateral and induced by ocular surgical intervention or by medical therapy. Here, we report a case of simultaneous bilateral malignant glaucoma in a young patient with no history of any ocular diseases.

CASE REPORT

A case of a 24-year-old female with no apparent previous history of ocular medical or surgical conditions was referred to our hospital because of recent bilateral IOP elevation associated with a severe drop in vision and shallow anterior chamber with no posterior segment anomalies detected by ocular ultrasound in both eyes. Yttrium aluminum garnet (YAG) laser iridotomy dropped the IOP only temporarily and the patient received topical atropine treatment with combined trabeculectomy and anterior vitrectomy.

RESULTS

In this case, the patient had a typical presentation of bilateral malignant glaucoma and her IOP dropped only temporarily following laser iridotomy to rise again shortly thereafter. Also, deepening of the anterior chamber and IOP decrease after topical atropine was very supportive of the diagnosis of malignant glaucoma. Successful management with trabeculectomy and limited vitrectomy also affirmed the diagnosis of malignant glaucoma.

CONCLUSION

This is a very rare case of bilateral malignant glaucoma in a young adult without any prior eye conditions; only one similar case has been reported in the literature. We propose our own theory regarding this simultaneous occurrence of the pathology based on previously published studies about the presence of communication between the two eyes along the cerebrospinal fluid pathways.

Development of ocular hypertension and persistent glaucoma after intravitreal injection of triamcinolone

Purpose

This study evaluates intraocular pressure (IOP) elevation secondary to intravitreal injection of triamcinolone acetonide (IVTA) and discusses its management.

Methods

The records of 175 patients who underwent IVTA treatment and regular eye examinations in the period 2003–2006 were reviewed. One hundred and twenty-two of these patients were included in the study, of which 147 eyes that received IVTA (4 mg/0.1 ml) were followed for at least 9 months. Mean IOPs observed after IVTA injection as well as IOP elevations defined as moderate (≥5 mm Hg), important (≥10 mm Hg) and severe (>25 mm Hg) during the follow-up period were evaluated and compared statistically.

Results

Overall, the mean IOPs following IVTA injection were statistically significantly higher than the preinjection IOP (15.8 ± 2.6), after the first hour (17.7 ± 2.9), the first week (18.7 ± 4.1), the first month (19.6 ± 6.2), the second month (19.1 ± 6.1), the third month (18.0 ± 4.1), the sixth month (17.3 ± 4.0), and the ninth month (17.0 ± 2.7), but not after the first day (16.3 ± 7.6). Important IOP elevations were observed mostly in the first (17.7%) and second months (10.2%). In 40 (27.7%) eyes, topical antiglaucomatous therapy was needed and 7 later required surgical intervention to lower the IOP. Of the remaining 33 eyes, topical treatment was continued in 14 (9.5%) because of IOPs ≥20 mm Hg.

Conclusion

The persistence of IOP elevation beyond the IVTA clearance period and the development of intractable secondary glaucoma requiring surgical intervention substantiate the need for careful consideration of IVTA indication and follow-up.

Steroid-induced iatrogenic glaucoma

Steroids in susceptible individuals can cause a clinical condition similar to primary open-angle glaucoma. Five percent of the population are high steroid responders and develop an intraocular pressure (IOP) elevation of more than 15 mm Hg above baseline. IOP elevation may occur as early as 1 day to as late as 12 weeks after intravitreal triamcinolone in 20-65% of patients. On average, 75% of eyes with steroid implants require IOP-lowering therapy at some point within 3 years of follow-up. The exact mechanism of steroid-induced glaucoma is not totally understood, but decreased trabecular meshwork outflow is regarded as the main cause of IOP elevation. High-risk patients who receive steroids should be monitored closely and if they develop elevated IOP, steroids with lower potency or steroid-sparing agents should be used. The IOP usually returns to normal within 2-4 weeks after stopping the steroid. About 1-5% of patients do not respond to medical therapy and need surgery. Trabeculectomy, trabeculotomy, shunt surgery, and cyclodestructive procedures are among the methods employed. Removal of residual sub-Tenon or intravitreal steroids may help hasten the resolution of the steroid response. Early results with anecortave acetate, an analog of cortisol acetate with antiangiogenic activity, in controlling IOP have been promising.

Effect of intravitreal injections and volume changes on intraocular pressure: clinical results and biomechanical model

PURPOSE

Intravitreal injections are used extensively to treat retinal diseases. Performing an intravitreal injection increases intraocular volume by the amount of fluid brought into the eye. Whether this influences intraocular pressure (IOP) was investigated here.

METHODS

A biomechanical model relying on 3-dimensional elasticity theory was developed to determine the short-term effect of volume changes on IOP. We calculated the effect for intravitreal injections of 0.1 ml in myopic, emmetropic and hyperopic eyes. Our calculations were compared with IOP measurements obtained immediately after intravitreal injection of 4 mg triamcinolone in 0.1 ml solution (IVTA) in 22 patients. Shortly after the measurement had been taken, IOP was reduced by paracentesis.

RESULTS

Immediately after IVTA, measured IOP was elevated by a mean of 40.6 +/- 12.1 mmHg compared with initial pressure (p < 0.001). Measured and calculated IOP were comparable. Eyes with shorter axial length had higher IOP immediately after the injection (p < 0.05).

CONCLUSIONS

The effect of injected volumes on IOP can be calculated with a biomechanical model. Our results show that paracentesis might be recommended when injecting 0.1 ml of a substance to avoid a short-term increase in IOP. As intravitreal injections are mostly applied in diseases that are due to vascular compromise, it might be prudent not to impair perfusion in those eyes, even for short periods of time.