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Diode laser trans-scleral cyclophotocoagulation (TSCPC) is a well accepted method for the management of patients with refractory glaucoma. A lasting decrease in IOP has been reported in about two thirds of eyes with severe, medically uncontrolled glaucoma following contact TSCPC using G-probe delivery, with preservation of visual acuity.1,2 Although the procedure is considered safe,3,4 complications have been reported.1,5 Here, we report the first case, to the best of our knowledge, of panophthalmitis following contact diode laser cyclophotocoagulation using the G-probe in a patient with failed trabeculectomy and trabeculotomy for congenital glaucoma.
An 18 year old male patient presented to our emergency service with a 4 day history of pain, redness, and periorbital swelling in the right eye, accompanied by poor vision. One week earlier he had undergone 360 degree diode laser trans-scleral cyclophotocoagulation using contact G-probe in the right eye for uncontrolled glaucoma. He had thrice undergone filtering surgeries in both eyes for congenital glaucoma since 1985. During the last trabeculectomy performed in 1996, intraoperative mitomycin C (0.2 mg/100 ml applied for 3 minutes beneath the scleral flap) had also been used. But it failed in the right eye and the patient had developed a painful blind eye.
His visual acuity was no light perception in the right eye and 20/60 in the left. There was right sided periorbital oedema, restricted motility, and purulent discharge with matting of the eyelashes. Rupture of the globe with prolapse of the iris was evident along the superior limbus. In the left eye the bleb was well formed, and the IOP (Goldmann applanation) was 12 mm Hg. The optic disc showed a cup disc ratio of 0.4 with temporal pallor.
A diagnosis of panophthalmitis of the right eye was made. As no response to intravenous antibiotic treatment was observed over the next 48 hours, evisceration was undertaken with the patient's informed consent. Staphylococcus epidermidis was grown on culture.
Its efficacy notwithstanding, diode laser cyclophotocoagulation has been associated with complications, although less frequent than with other cyclodestructive procedures. Conjunctival burns, corneal decompensation, neurotrophic corneal defects, uveitis, IOP spikes, phthisis (0.5%), chronic hypotony (1%), macular pucker (0.5%), intraocular haemorrhage (0.5%), visual loss, and malignant glaucoma have all been reported.1,5–8 Possible correlation of outcome with perilimbal pigmentation, and the hearing of audible “pop,”6 especially in patients with dark brown irides,4 has been suggested.
Scleral thinning is a recognised risk factor for complications, but scleral perforation following this procedure has been reported earlier in one patient only.9 This patient had scleral thinning following previous cataract surgery. Possibly, the sharp probe edge had cut conjunctival vessels causing bleeding and contamination of the probe tip. Thin adherent debris was then carbonised allowing the laser tip temperature to rise to 300°C, sufficient to cause scleral perforation. This report led to redesigning of the probe tip to protect the vascular structures from its sharp edges.
Our patient was treated as part of a standard protocol using the modified G probe, and bleeding did not occur. The perforation could have resulted from mechanical pressure, or the effect of the laser on the thinned out sclera, which the patient probably had as a result of buphthalmos and previous ocular surgery.9 There are no known “corrective factors” to utilise in eyes with severe scleral thinning, and if treatment is absolutely necessary, a 40% lower energy should be used,10 and areas of thinning and possible wound dehiscence, such as the bleb, should be avoided. We emphasise caution in undertaking contact diode laser trans-scleral cyclophotocoagulation in operated eyes with thin sclera.