Contact Diode Laser Cyclophotocoagulation Research Articles

Effect of Diode Laser Cyclophotocoagulation on the Anterior Segment

To evaluate the effect of transscleral contact diode laser cyclophotocoagulation (TCDLC) on corneal topography, central corneal thickness (CCT), and anterior-chamber depth (ACD). The Orbscan II system was used to determine the changes in corneal topography, CCT, and ACD before and after TCDLC in 25 eyes of 24 patients. Mean prelaser astigmatism was 4.51 +/- 1.81, 4.64 +/- 3.47, and 5.40 +/- 3.04 D at central and 3- and 5-mm zones, respectively. Mean postlaser astigmatism was 4.54 +/- 2.59, 4.75 +/- 3.33, and 5.57 +/- 3.12 D at central and 3- and 5-mm zones at 10 days and 3.99 +/- 2.01, 4.05 +/- 2.20, 5.52 +/- 4.60 D at 1 month, respectively, showing no statistically significant difference. Prelaser CCT was 540.72 +/- 103.48 microm. Postlaser CCT was 617.08 +/- 86.35 microm at 10 days and 569.88 +/- 70.36 microm at 1 month. CCT was significantly thicker at 10 days compared with prelaser CCT, whereas CCT at 1 month was not statistically different. ACD showed a nonsignificant decrease after TCDLC from 3.77 +/- 0.81 to 3.38 +/- 0.85 mm at 10 days and 3.58 +/- 0.78 mm at 1 month. TCDLC does not alter corneal topography or ACD significantly. However, CCT increases during the 10 days after TCDLC and returns to normal at 1 month, which might be related to the inflammation induced by cyclophotocoagulation. Increased CCT may lead to artificially high intraocular pressure measurements within the first 4 weeks after surgery.

Inadvertent sclerostomy with encysted bleb following trans‐scleral contact diode laser cyclophotocoagulation

A 22-year-old woman underwent 360 degrees trans-scleral contact diode laser cyclophotocoagulation for refractory glaucoma. Conjunctival burns and scleral thinning were noticed inferonasally at the last laser application. Intraocular pressure in the first week was normal. Six months later the patient presented with encysted filtering bleb and high intraocular pressure. Ultrasound biomicroscopy revealed a full thickness sclerostomy. This report suggests that inadvertent sclerostomy may present with encysted bleb months after trans-scleral contact diode laser cyclophotocoagulation.

Iris Retraction and Retroflexion After Transscleral Contact Diode Laser Photocoagulation

A 9-year-old girl with refractory glaucoma with an anterior chamber intraocular lens underwent transscleral contact diode laser cyclophotocoagulation. Slit-lamp examination and ultrasound biomicroscopy revealed iris retraction and retroflexion at 2 weeks of follow-up. The probable cause of this complication is discussed.

Pupillary distortion and staphyloma following transscleral contact diode laser cyclophotocoagulation; a clinicopathological study of three patients

Pupillary distortion and staphyloma following transscleral contact diode laser cyclophotocoagulation; a clinicopathological study of three patients

Subconjunctival Anesthesia in Contact Diode Laser Cyclophotocoagulation

Retro- or peribulbar anesthesia are the standard procedures for cyclodestructive surgery. Because these methods of anesthesia may further compromise optic nerve function, especially in advanced glaucoma, subconjunctival anesthesia was evaluated as an alternative procedure in contact diode laser cyclophotocoagulation (CPC). A prospective study concerning diode laser CPC in advanced glaucoma was started using subconjunctival anesthesia with 2% mepivacaine. Complications and pain during CPC (5 point rating scale) and on the first postoperative day were recorded. Only the first CPC in every patient was included for evaluation. Included in the study were 120 eyes of 120 patients. During CPC, 82.5% of patients experienced no pain, 11.7% mild pain, and 5.8% moderate pain. No instances of pain or excess motion occurred that required peribulbar anesthesia or discontinuation of the procedure. Most of the patients experienced no pain during diode laser CPC using subconjunctival anesthesia. Therefore, risks and side effects of retro- or peribulbar anesthesia can be successfully avoided by this simple modification.

Diode Laser Cyclophotocoagulation: Histopathology in Two Cases of Clinical Failure

Diode laser photocoagulation is an alternative technique to Nd:YAG laser or cryotherapy in cycloablation. It may be more titratable with fewer local side effects. The effect is not, however, always maintained in the long term. The authors wished to establish histologic correlates with in vivo clinical outcomes of failure. Histologic findings in two cases of clinical failure of a single treatment with contact diode laser cyclophotocoagulation are presented. A recurrence of uncontrolled intraocular pressure (IOP) finally led to enucleation of the eyes 5 and 6 months after laser treatment. Histologic examination demonstrated preservation in both specimens of some ciliary processes outside the treatment zone, which was evidently over the pars plana in a case with a relatively low axial length. Persisting damage of treated ciliary processes was seen. Some efforts at ciliary epithelial regeneration were made in these, but in a disorganized and presumably nonfunctional fashion, so that a histologic explanation for the gradual postoperative rise in IOP was not evident. Diode laser cyclophotocoagulation may lower IOP by mechanisms other than destruction of ciliary epithelium. Reversal of a laser-induced increase in uveoscleral outflow may explain the gradual rise in IOP seen postoperatively in these two cases, given the ineffectual secretory epithelial regeneration in one case and the treatment over the pars plana in the other. Methods to enhance probe placement, such as ultrasound biomicroscopy, transillumination, or axial length measurement, may be useful to ensure that treatment is directed to the pars plicata. [Ophthalmic Surg Lasers 1998;29:852-856.] Cyclodestructive procedures have been likened to "duck hunting in the dark (without radar) since the 'shooter' sees neither the target nor the effect of the blast!" Although the use of Nd:YAG and semiconductor diode laser cyclophotocoagulation instead of cyclocryotherapy has progressively refined the caliber of the weapon and its titratability, aim in the placement of the destruction remains inexact. The assumption has generally been, however, that treatment must be directed to ablation of the ciliary epithelium to achieve a hypotensive effect. We present the histopathology from two cases of contact diode laser cyclophotocoagulation (DLCPC), both of which resulted in initially successful intraocular pressure (IOP) control, but which finally required enucleation for problems supervening on a recurrently raised IOP.

Diode laser cyclophotocoagulation in treatment of therapy refractory glaucoma

It has been suggested that Nd:YAG laser cyclophotocoagulation significantly lowers the intraocular pressure in refractory glaucoma. However, only limited information is currently available concerning the cyclodestructive effects of diode laser cyclophotocoagulation. Twenty eyes of 17 patients had undergone diode laser cyclophotocoagulation if previous glaucoma surgery including cyclocryocoagulation was unsuccessful or the patients were blind. Nine eyes had secondary glaucoma, 5 neovascular glaucoma, 5 congenital glaucoma, and 1 eye chronic open angle glaucoma. Treatment was applied in two quadrants using a 810 nm diode laser (600 qm diameter quartz fiber, 2 sec, 1.75-3 W, 6 to 10 pulses). Seven eyes required retreatment. In 19 eyes the baseline IOP was 32.1 +/- 10.1 mm Hg and at the patient's last examination 21.0 +/- 8.4 mm Hg. Median follow up was 11 months (3 to 19 months). In 4 of 5 eyes with a visual acuity of less than 1/50 IOP was decreased under 30 mm Hg, while 9 of 14 eyes with a visual acuity of at least 1/50 IOP revealed a decrease of IOP under 20 mm Hg, resulting in a success rate of 68%. Complications included acute severe anterior uveitis in one eye and bulbus hypotonia in another for several months. After three weeks, one eye was enucleated because of persisting high IOP and pain. Histopathologically, coagulation necrosis of the ciliary body stroma and separation of epithelial layers were observed. This study suggests that contact diode laser cyclophotocoagulation is an effective method and a valid alternative to cyclocryocoagulation in the treatment of refractory glaucoma including congenital glaucoma.