Internal sclerostomy with a high-powered argon laser

A full-thickness sclerostomy from the anterior chamber to the subconjunctival space was created in 9 eyes of 7 rhesus monkeys using an argon endolaser. After the injection of sodium hyaluronate into the subconjunctival space and the anterior chamber, a 300 microns fiberoptic fiber coupled with an argon laser (HGM, model 20) was inserted to the anterior chamber and positioned at the trabecular meshwork. A patent sclerostomy was created in all 9 eyes by 1 to 3 laser pulses with an energy of 4W with a duration of 0.5 second. Preoperative intraocular pressure in treated eyes and untreated eyes, measured with a pneumatic tonometer, was the same. After one month, the intraocular pressure of the treated eyes was 4.6 +/- 0.4mmHg lower than that of the untreated eyes. Histologic study revealed that the sclerostomies with a diameter of 200-300 microns from the anterior chamber opening to the subconjunctival space were patent at one month after the treatment. Internal sclerostomy with a high powered argon endolaser may hold potential as a new filtering procedure which can easily be performed with a minimum of conjunctival damage.     

Ab interno laser sclerostomy in aphakic patients with glaucoma and chronic inflammation

Five patients with aphakia, glaucoma, and chronic inflammation were treated with ab interno sclerostomy by using the continuous wave Nd:YAG laser focused through a sapphire probe. After a follow-up period of 24 to 28 months, three of five patients had good intraocular pressure control. The sclerostomy failed in one patient when it was occluded by vitreous. The second failure was attributed to closure of the sclerostomy because of chronic intraocular inflammation.     

Histologic study of healing after ab interno laser sclerostomy.

We examined the histologic characteristics of healing after ab interno laser sclerostomy in a human eye. A KTP 532 green laser coupled to a 300-microns quartz fiberoptic probe was used to create an ab interno sclerostomy in a terminally ill patient with pigmentary glaucoma. The intraocular pressure increased five days postoperatively and did not respond to medical treatment. The patient died six weeks postoperatively of metastatic lung cancer. Histopathologic analysis showed a patent 150-microns scleral lumen from the anterior chamber to the episclera, surrounded by a 300-microns zone of acellular thermal damage. There was no healing of the lumen. The subconjunctival end of the lumen was capped with a thick episcleral scar, which caused the failure of the operation.     

Ab interno resection of uveal melanoma

Uveal melanomas located 1 to 2 disc diameters from the disc are difficult to manage. An internal resection approach (retinochoroidectomy ab interno) for the removal of melanomas has been developed and used to remove tumors in four patients. In five additional patients this procedure was combined with external resection to remove residual suspicious tissue from the resected margins.     

Laser sclerostomy ab interno using continuous wave and pulsed lasers in a rabbit model

Purpose: This experimental study was designed to find an optimal combination of parameters for a gonioscopic ab interno approach to laser sclerostomy.Methods: Laser sclerostomy ab interno was performed delivering the laser energy via a slit lamp and a gonioscopic contact lens to the iridocorneal angle. The laser energy is required to be well transmitted by the cornea and at the same time to be maximally absorbed by the sciera at the iridocorneal angle. For local enhancement of absorption the sciera was stained with the biocompatible dyes Fluorescein (absorption maximum at 480 nm) and Methylene blue (absorption maximum at 668 nm) applied by iontophoresis. A continuouswave (cw)-Argon laser and a cw-dye laser produced relatively long pulses (200 ms) at wavelengths matching with these respective maxima. Additionally a pulsed dye laser emitting shorter pulses (2s) was successively adapted to the wavelengths of the two maxima. In some cases a Q-switched Nd: YAG laser had to be used for perforation of Descemet's membrane. A total of 44 rabbit eyes was treated to compare the results for these four different laser/dye combinations.Results: While no successfull perforation of the sciera could be achieved using the cw-dye laser with scleral staining by Methylene blue, the intraoperative success rate ranged between 59% and 75% for the other three laser/dye combinations. Histological examinations of the eyes on the first postoperative day showed smaller thermal necrosis zones, but more often fibrin reactions when using the shorter pulse length. Although we often found iris adherences to the internal fistula ostium, no major complications were observed.Conclusion: Further improvement of intraoperative success rates is needed, before clinical application of the approach can be considered.     

Internal sclerostomy with argon contact laser--animal experiment using 5-fluorouracil

A full-thickness sclerostomy was carried out with an ab interno approach, using an argon endolaser, in 9 eyes of 7 rhesus monkeys. After the injection of sodium hyaluronate into the subconjunctival space and the anterior chamber, a 300 micron fiber optic probe coupled with a water-cooled argon laser was inserted into the anterior chamber through the corneal incision made by a 23-gauge needle and positioned on the trabecular meshwork opposite to the corneal incision. A patent sclerostomy was obtained in all 9 eyes by 1 to 3 laser pulses with an energy of 4 W and a pulse duration of 0.5 seconds. After the surgery, 0.1 ml of 5-fluorouracil was injected subconjunctivally every day for one week. Intraocular pressure (IOP) was determined by pneumatic tonometer for one month at appropriate intervals. Mean preoperative IOP was 22 mmHg in both operated and nonoperated eyes. After one month IOP was 4.6 +/- 0.4 mmHg lower in the operated eyes than in the nonoperated eyes. Histologic study revealed that the sclerostomies from the anterior chamber opening to the subconjunctival space with the diameter of 200-300 microns still remained patent one month after surgery. Ab interno sclerostomy with an argon endolaser would be useful as a new filtering procedure which can easily be performed with minimum conjunctival damage.     

Gonioscopic ab interno laser sclerostomy. A pilot study in glaucoma patients.

PURPOSE: The purpose of this study is to evaluate the safety and efficacy of gonioscopic ab interno laser sclerostomy (GLS) in patients with glaucoma. METHODS: The technique of GLS involves iontophoresis of methylene blue dye (1%) at the limbus to focally dye the sclera and to provide subsequent delivery of 10-microsecond pulsed laser energy to the dyed area through a goniolens. The laser emits at 660 nm, a wavelength that is maximally absorbed by the methylene blue dye. Patients were evaluated for fistula formation, intraocular pressure (IOP) reduction, and adverse sequelae. Thirty-eight treatments were performed in 35 eyes. RESULTS: Successful complete sclerostomies were achieved in 21 eyes (55%), which was associated with an acute mean reduction in IOP of 23 mmHg. Mean preoperative IOP for all patients was 35 mmHg, and 1 hour after treatment it was reduced to 18.5 mmHg. In 4 of the 38 treatments, there was no acute IOP reduction, and these eyes were judged as failures. The mean follow-up time was 8.2 months with a maximum follow-up of 15 months. By 9 months, 50% of patients had an IOP of 22 mmHg or lower. The number of antiglaucoma medications decreased from 3.1 to 1.7 for all eyes over the 15-month follow-up period. Hyphemas (13%) were the only major complication, and these resolved spontaneously. In only one case did the IOP increase after the procedure. CONCLUSION: The results of this trial indicate that GLS is technically feasible, and preliminary results of IOP control are promising.     

Ab interno sulcus placement of glaucoma tube implants

A modified technique for sulcus placement of glaucoma silicone tubes is described. Sulcus placement can be useful in patients with penetrating keratoplasty or in those who are at risk for corneal endothelial decompensation. However, correct placement can be difficult to confirm with a traditional ab externo approach. An ab interno technique for sulcus placement of glaucoma tube implants that both offers an easier approach and facilitates accurate positioning is described.     

External argon laser drainage of subretinal fluid using the endolaser probe

The results of 200 consecutive scleral buckling procedures in which the argon endolaser probe was used to create a choroidotomy for drainage of subretinal fluid are reported. This technique was used in any case requiring drainage and was specifically employed in cases in which needle drainage was contraindicated because the detachment was shallow. The argon laser was set at 0.2 seconds, 1.25 watts, and was used with the endolaser probe held adjacent to, but not touching, the choroid. Drainage was successfully accomplished in 98% of cases. Rates of subretinal hemorrhage, retinal incarceration, and perforation related to laser drainage were 5.5%, 2.5%, and 1%, respectively. No large or submacular subretinal hemorrhages occurred. This technique appears to be particularly promising for drainage of shallow retinal detachments.     

Ab interno trabeculectomy with Trabectome: outcomes in African American versus Caucasian patients

Objective

To compare the intraocular pressure–lowering efficacy and complication rate of ab interno trabeculectomy with the Trabectome between African American (AA) and Caucasian patients with open-angle glaucoma.

Goniotomy Ab interno “a glaucoma filtering surgery” using the fugo plasma blade

Sixteen eyes with absolute glaucoma were treated and followed up for a minimum of six months. Goniotomy ab interno using the Fugo Blade^™ was found to be a safe alternative to conventional trabeculectomy, which safely and effectively reduced intraocular pressure in more than 80% of cases. The authors have stated that they do not have a significant financial interest of other relationship with any product manufacturer or provider of services discussed in this article. The authors also do not discuss the use of off-label products, which include unlabeled, unapproved, or investigative products or devices.     

Ab interno trabeculectomy: ultrastructural evidence and early tissue response in a human eye

PURPOSE: To report the results of ultrastructural analysis of the postoperative effects of ab interno trabeculectomy in a human eye. SETTING: Department of Ophthalmology, Palmanova Hospital, Palmanova, Udine, Italy. METHODS: A 60-year-old woman with cataract and glaucoma had enucleation for a choroidal melanoma 10 days after ab interno trabeculectomy combined with phacoemulsification. A second ab interno trabeculectomy was performed after enucleation to evaluate the outcomes of the previous trabeculectomy. Light and transmission electron microscopy analyses were performed on samples excised from areas (1) not subjected to a procedure (control samples), (2) that had ab interno trabeculectomy before enucleation, and (3) that had ab interno trabeculectomy immediately after enucleation. RESULTS: Control samples showed normal trabecular features. Semithin sections of all ab interno trabeculectomy samples showed full-thickness removal of trabeculum segments, with Schlemm's canal lumen opening into the anterior chamber and apparent preservation of the adjacent structures. On ultrathin sections of samples that had ab interno trabeculectomy before enucleation, the endothelium lining the outer wall of Schlemm's canal and other angle components showed intact ultrastructural features. In trabecular beams that were not removed, the extracellular matrix appeared to have maintained its fine texture and was free of activated fibroblasts or leucocyte infiltrates. CONCLUSIONS: Observations confirm that ab interno trabeculectomy causes direct communication between Schlemm's canal lumen and the anterior chamber in vivo and immediately after enucleation during the early postoperative period. The absence of an evident inflammatory reaction in the examined case should be considered with caution because of possible tumor-induced immune suppression.