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At least 19 recordsLinked to original sources
PubMed1988

Internal sclerostomy with the Nd: YAG contact laser versus thermal sclerostomy in rabbits.

The authors undertook an investigation to evaluate the efficacy and complications of performing internal sclerostomy with the synthetic sapphire contact neodymium:YAG (Nd:YAG) laser compared with standard external thermal sclerostomy. Fifteen rabbits underwent internal laser sclerostomy in one eye; 12 additional rabbits underwent a standard external thermal sclerostomy in one eye. The fellow eyes served as controls. The differences between the groups in duration of functional blebs and pressure reduction were statistically significant (P = 0.034 and 0.0013, respectively). The evaluation of success (as determined by a pressure reduction greater than 3 mmHg between both eyes after digital pressure) using life-survival analysis indicated that the success rate of the laser-treated group was significantly different from the standard surgical group (P = 0.002). Histologically, there was less inflammation in the laser-treated group 2 days postoperatively. The complications of the laser treatment include focal injury to the overlying cornea, adjacent iris stroma, and lens.

Aluminum Silicates↗
PubMed1998

[Ab externo erbium YAG laser sclerostomy versus conventional trabeculectomy. Treatment of glaucoma patients].

PURPOSE: This study was conducted to compare the efficacy of the Er-YAG laser sclerostomy ab externo versus trabeculectomy in the treatment of primary open-angle glaucoma. METHODS: Twelve patients with POAG underwent ab externo laser sclerostomy using an Er-YAG laser (Sklerostom 2.9; lambda = 2940 nm, t = 200 microseconds, 2 Hz, 400 microns, 15 mJ). Only local medication was used, and there were no risk factors for failure. As a control group 12 patients out of 248 standardized trabeculectomies were matched in terms of age, sex, diagnosis and local medications. No antimetabolites were used in either group. RESULTS: After a follow-up of 9 months in the sclerostomy group 53%; (7/12; P = 0.03) showed a patent fistula in comparison of 100% in the trabeculectomy group. There was a significantly lower mean IOP during the first postsurgical week in the group of sclerostomies (3.6 +/- 1.5 mmHg versus 7.5 +/- 2.7 mmHg; P = 0.0001) with a higher incidence of choroidal detachments (9/12 versus 2/12; P = 0.004). The choroidal detachments lasted longer in the sclerostomy group (3.5 months versus 0.3 months; P = 0.014). Iris incarcerations were found only in sclerostomies (7/12; P = 0.05). CONCLUSIONS: Based on these findings, Er-YAG laser sclerostomy prooved to be less effective than trabeculectomy in the treatment of glaucoma patients. Er-YAG laser sclerostomies were associated with a higher incidence of postsurgical complications such as hypotony, choroidal detachments and iris incarcerations. At this point Er-YAG laser sclerostomy is not superior to conventional trabeculectomy.

Aged↗
PubMed1994

193 nm excimer laser sclerostomy in pseudophakic patients with advanced open angle glaucoma.

A modified open mask system incorporating an en face air jet to dry the target area during ablation and a conjunctival plication mechanism, which allows ab externo delivery of the 193 nm excimer laser without prior conjunctival dissection, has been developed to form small bore sclerostomies accurately and atraumatically. Full thickness sclerostomies, and sclerostomies guarded by a smaller internal ostium can be created. A pilot therapeutic trial was conducted in pseudophakic patients with advanced open angle glaucoma. Six full thickness sclerostomies (200 microns and 400 microns diameter) and three guarded sclerostomies were created in nine patients by 193 nm excimer laser ablation (fluence per pulse 400 mJ/cm2, pulse rate 16 Hz, air jet pressure intraocular pressure +25 mm Hg). After 6 months' follow up, intraocular pressure was controlled (< or = 16 mm Hg) in eight of the nine patients (6/9 without medication). Early postoperative complications included hyphaema (trace--2.5 mm) (6/9), temporary fibrinous sclerostomy occlusion (4/9), profound early hypotony (all patients without fibrinous occlusion), and suprachoroidal haemorrhage in one case. Conjunctival laser wounds were self sealing. Small bore laser sclerostomy procedures are functionally equivalent to conventional full thickness procedures, producing early postoperative hypotony, with an increased risk of suprachoroidal haemorrhage in association with this. Further research is required to improve control over internal guarding in excimer laser sclerostomy before clinical trials of this technique can safely proceed.

Cataract Extraction↗
PubMed1997

Prospective study of ab externo erbium:YAG laser sclerostomy in humans.

PURPOSE: To evaluate the efficacy of ab externo erbium:YAG (Er:YAG) laser sclerostomy in controlling intraocular pressure in eyes with uncontrolled glaucoma. METHODS: We performed ab externo laser sclerostomy on eyes of 26 patients. Mean +/- SD postoperative follow-up was 11.4 +/- 0.9 months. Complete success was defined as intraocular pressure below 22 mm Hg with no adjunct medication; qualified success was defined as intraocular pressure below 22 mm Hg with medication. RESULTS: In all eyes, ab externo Er:YAG laser sclerostomy achieved a functioning fistula with a prominent filtering bleb. Twelve eyes had had neodymium:YAG (Nd:YAG) laser iridotomy at the site of laser sclerostomy 2 weeks before filtering surgery; 14 eyes had surgical iridectomy at the site of laser sclerostomy. Mean preoperative intraocular pressure of 30.7 +/- 7.3 mm Hg (range, 17.0 to 48.0 mm Hg) was significantly (P < .05) reduced to 18.3 +/- 1.0 mm Hg (range, 0 to 25.0 mm Hg) at 2 weeks postoperatively. thereafter, marked regression was noted: at 1 month postoperatively, intraocular pressure was 20.1 +/- 9.5 mm Hg (range, 4.0 to 44.0 mm Hg); half-life of complete success was 25 days; of qualified success, 56 days; and of a functioning filtering bleb, 36 days. CONCLUSIONS: Ab externo Er:YAG laser sclerostomy reliably created successful full-thickness fistulae with prominent filtering blebs in human glaucomatous eyes. However, a transient phase of ocular hypotony caused by aqueous overfiltration, followed by an ongoing rate of fistula patency failure, renders Er:YAG laser sclerostomy, as performed in this study, unsuitable for long-term pressure control.

Adult↗
PubMedDate not supplied

Internal sclerostomy with the Er:YAG laser using a gradient-index (GRIN) endoscope.

BACKGROUND AND OBJECTIVE: To show that sclerostomy, a glaucoma filtering surgery, can be performed using an Er:YAG laser. Scarring at the filtering site, a recurrent problem, may be reduced through proper positioning of the sclerostomy by using an intraocular endoscope. MATERIALS AND METHODS: Ab interno full-thickness sclerostomies were performed on eye bank eyes with an Er:YAG laser through a custom made optical delivery system. The intraocular laser probe consisted of a low OH silica fiber inserted in a metallic tapered sheathing. A rigid intraocular endoscope based on gradient-index lenses allowed visualization of the filtration site. RESULTS: A clear view of the anterior chamber angle was obtained through the endoscope, allowing for precise location of the sclerostomy. Full-thickness sclerostomies could then be performed at the desired location. Histologic sections showed thermal necrosis less than 50 microm thick in tissue adjacent to the sclerostomy. CONCLUSIONS: A sclerostomy performed with a combined procedure using an Er:YAG laser and intraocular endoscopy increases the speed of the procedure. The use of a high-resolution intraocular endoscope may increase the success rate of ab interno laser glaucoma surgeries.

Endoscopy↗
PubMed1993

Ab-interno erbium (Er):YAG laser sclerostomy with iridotomy in Dutch cross rabbits.

An ab-interno technique using a pigmented rabbit model has been developed that uses a pulsed erbium:YAG laser to create an iridotomy with a sclerostomy through the same corneal incision. Laser energy was delivered with an articulated arm terminating in side-firing (850 or 650 microns OD) or end-firing (850 or 400 microns OD) fiber optic endoprobes, which allowed iridotomies and sclerostomies, respectively, to be created. Initially, sclerostomies (8-10, 8 mJ/300 microseconds pulses) and basal iridotomies (1-3, 4 mJ/200 microseconds pulses) were created with the larger probes. Problems encountered with this technique included corneal decompensation and rapid formation of peripheral anterior synechiae with occlusion of sclerostomies. The smaller endoprobes were then used to create mid-peripheral iridotomies and sclerostomies utilizing the same energy parameters. Sclerostomies created in this manner remained patent in the first postoperative week until the animals were sacrificed to obtain material for histologic study.

Animals↗
PubMedDate not supplied

Evaluation of laser sclerostomy fistulas using ultrasound biomicroscopy.

BACKGROUND: Laser sclerostomy is a relatively new technique in glaucoma surgery. Clinical examination, particularly of the intrascleral part of laser sclerostomy fistulas, is difficult. We performed ultrasound biomicroscopy (UBM) in order to determine, if it were possible to visualize fistulas. Moreover, it was the aim to investigate whether this imaging technique could provide additional information on fistula morphology. PATIENTS AND METHODS: Ten eyes of eight patients with chronic open angle glaucoma who had undergone erbium-YAG laser sclerostomy ab externo were examined using a UBM-probe with a 20 MHz transducer providing spatial resolution of approximately 80 microm. RESULTS: Radial scanning allowed visualization of the sclerostomy fistula in nine of ten eyes. The different functional state of sclerostomy fistulas correlated well to UBM findings. It was possible to image differences in the morphology of occluded and patent fistulas and to visualize the filtering pathway in functioning blebs. CONCLUSIONS: Ultrasound biomicroscopy allows imaging of laser sclerostomy fistulas. UBM and clinical findings correlated well in the majority of the patients we examined. The technique supplements clinical examination and in some cases may provide additional information.

Aged↗
PubMed1994

A model for fluid mechanisms in sclerostomy.

The hydrodynamic mechanisms which subserve the outflow of newly created outflow canals in sclerostomy procedures are to a large extent obscure. The model presented here has strong analogies to a closed electric circuit and assumes that aqueous humor is pumped by the secretion pump into the anterior chamber, leaves the eye via the artificially created sclerostomy canal, and returns via the venous and arterial system to the ciliary body. The model attempts to describe the stationary situation which determines the intraocular pressure following sclerostomy in terms of the internal resistance of the secretion pump, the resistance in the sclerostomy canal, the resistance beyond the external ostium of the sclerostomy canal, the pressure in the anterior chamber, the pressure beyond the external ostium of the canal, and the secretion pressure exerted by the secretion pump.

Anterior Chamber↗
PubMed1993

193-nm excimer laser sclerostomy using a modified open mask delivery system in rhesus monkeys with experimental glaucoma.

Excimer laser sclerostomy is a new glaucoma filtration procedure in which the argon fluoride excimer laser at 193 nm is delivered ab externo through a modified open mask system incorporating an en-face air jet to dry the target area and preserve hemostasis during ablation and a conjunctival plication mechanism, which allows the conjunctival and scleral wounds created by through-and-through ablation to separate once the mask is removed. No preparatory dissection of the conjunctiva is required. Five 200-microns and five 500-microns sclerostomies were formed by ablation at a pulse repetition rate of 20 Hz and a fluence per pulse of 400 mJ/cm2 in fellow eyes of five rhesus monkeys with experimental glaucoma. Overall, seven of the ten eyes attained a functional result, with intraocular pressures remaining below 21 mmHg for 6 +/- 1 days and rising to the pre-operative level after 10 +/- 3 days without adjunctive antifibroblast medication. The duration of filtration for 200-microns and 500-microns sclerostomies was similar, and parallels that previously observed for posterior lip sclerectomy in the same animal model. The three eyes with no functional result all had incorrectly positioned sclerostomies. Choroidal detachment and significant shallowing of the anterior chamber did not occur. Excimer laser sclerostomy appears to be a viable technique for filtration, provided that mask placement is accurate.

Animals↗
PubMed1997

Gonioscopic laser sclerostomy versus filtration surgery in a rabbit model.

In a prospective and randomised study, we compared the course of pulsed dye laser ab interno sclerostomy with the course of posterior lip sclerectomy in 25 rabbits. One eye of each rabbit was randomly selected to be treated with laser; the fellow eye underwent posterior lip sclerectomy. Intraocular pressure (IOP) determinations and slit lamp examinations were recorded pre-operatively, then every other day for 3 weeks on 21 of the rabbits. Histological examination was performed on the eyes of 3 randomly selected rabbits that were killed 72 hours post-operatively. Laser sclerostomy resulted in an average maximal drop in IOP of 9.5 mmHg on post-operative day 1, and posterior lip sclerectomy resulted in a similar drop of 10.5 mmHg (p = 0.43, t-test). By life-table analysis, 88% of eyes returned to within 2 mmHg of pre-operative IOP values within 7 days following either laser internal sclerostomy or posterior lip sclerectomy. There was no significant difference between laser internal sclerostomy and posterior lip sclerectomy eyes with respect to the number of days needed to return to within 2 mmHg of preoperative IOP values (p = 0.26, sign test of the life-table analysis). Pulsed dye laser internal sclerostomy appears to be as effective as posterior lip sclerectomy in lowering IOP in the rabbit model.

Animals↗
PubMedDate not supplied

Use of the giant-pulse Nd:YAG laser for ab-externo sclerostomy in rabbits and humans.

The giant-pulse Neodymium:YAG laser, a recently developed laser source, delivers up to 200 W of peak power at pulse widths of 20 or 40 msec. The instrument can create a sclerostomy with minimal surrounding damage and, consequently, relatively little postsurgical inflammation and scarring. We tested its efficacy in performing ab-externo sclerostomy in 10 adult pigmented rabbits and in five patients with end-stage glaucoma. All of the animal eyes were hypotonus immediately after the procedure. However, the intraocular pressure increased gradually, and by the third day, returned to presurgical levels in all of the eyes. All five of the glaucoma patients treated had patent sclerostomies following the procedure. They all had early hypotony, but after 3 months, four of the five sclerostomies apparently failed. The giant-pulse Nd:YAG laser appears useful for performing sclerostomy, but modifications are needed to solve the problems of early hypotony and late closure of the fistulula.

Animals↗
PubMed1993

Subconjunctival THC:YAG ("holmium") laser thermal sclerostomy ab externo. A one-year report.

BACKGROUND: Laser sclerostomy can be performed in a less-invasive manner than standard filtering surgery. Longer wavelengths in the infrared range have water-absorptive characteristics that facilitate perforation of the sclera. The goal was to perform laser sclerostomy ab externo to avoid intraocular instrumentation and minimize conjunctival trauma. METHODS: A thulium, holmium, chromium-doped:YAG (THC:YAG) crystal laser was used to create thermal sclerostomies in 49 glaucomatous eyes of 46 patients. The laser is a long-pulsed (300-microsecond), compact, self-contained, solid-state laser operating in the near infrared (2.1 microns). Energy was delivered via a specially designed 22-gauge (712-microns) optic probe that emits energy at a right angle to the long axis of the fiber. Pulse energies of 80 to 120 mJ were used. Total energy levels to produce full-thickness sclerostomies ranged from 1.4 to 7.2 J. Subconjunctival 5-fluorouracil (5-FU) injections were administered in 46 eyes. Success was defined as an intraocular pressure (IOP) of less than or equal to 22 mmHg with or without medications. For eyes in which preoperative IOP was less than or equal to 22 mmHg, success was defined as a decrease in IOP of greater than or equal to 30%. RESULTS: Estimated probability of success allowing for one retreatment was 0.75 at 6 months and 0.68 at 12 months. Mean IOP of successful cases was 13.3 mmHg at both 6 and 12 months. Twelve cases failed within the initial 6 months, and two additional cases failed by 12 months. CONCLUSION: THC:YAG ("holmium") laser thermal sclerostomy is an alternative to other full-thickness filtration procedures. Further evaluation and understanding will define its ultimate role in glaucoma management.

Adolescent↗
PubMedDate not supplied

Holmium laser sclerostomy via corneal approach with transconjunctival mitomycin-C in rabbits.

We studied the use of the holmium laser for sclerostomy through a small lamellar corneal incision and the effects of transconjunctival mitomycin-C on the outcome of filtration surgery without conjunctival incision. The holmium laser, equipped with a straight-firing probe, was used to create sclerostomies in seven New Zealand white rabbits through a corneal lamellar incision. One eye in each rabbit was treated with transconjunctival mitomycin-C (0.4 micrograms/mL for 5 minutes), and the fellow eye underwent sclerostomy without pretreatment with mitomycin-C as a control. The reduction in intraocular pressure was greater and persisted significantly longer in the eyes pretreated with mitomycin-C than in the controls. All control eyes had flat blebs by day 7 to 12, while the treated eyes maintained a bleb throughout the study. Microscopic examination showed that sclerostomies created by the straight-firing probe induced significantly less thermal damage than those created by the stationary side-firing probe. These results demonstrate that successful transcorneal sclerostomy without conjunctival incision can be created using the straight-firing holmium laser probe, with enhancement of filtration by pretreatment with transconjunctival mitomycin-C.

Animals↗
PubMed1998

Histologic effect of diode laser sclerostomy in human cadaver eyes.

BACKGROUND AND OBJECTIVES: To study tissue effects and thresholds of efficacy in producing a full-thickness scleral fistula in human eyes obtained from cadavers. The effect of laser sclerostomies created with indocyanine green (ICG) was also evaluated. MATERIALS AND METHODS: Ab externo laser sclerostomies were produced in 12 fresh human eyes obtained from cadavers using a 200-micron diameter fiber optic connected to a diode laser system. Power settings were 500, 750, 1000, 1250, 1500, and 2000 mW with a constant duration of 100 and 200 ms. The same diode laser settings were repeated in the tissues injected with ICG. RESULTS: The laser sclerostomies were associated with heat coagulation damage adjacent to the burn margins, with disruption of stromal collagen. Tissue damage was greater at higher power and longer duration. Scleral injection of ICG prior to laser sclerostomy did not enhance laser penetration. CONCLUSION: The diode laser can create a sclerostomy in human sclera with an optimum level of 1500 mW and 100 ms. ICG did not significantly enhance the ease of penetration or reduce the association thermal damage to the sclera.

Coloring Agents↗
PubMed1985

Congenital glaucoma with corneal cloudiness treated by thermal sclerostomy.

Thermal sclerostomy (the Scheie procedure) was performed on nine eyes with congenital glaucoma and corneal cloudiness. The intraocular pressure was controlled and the cornea cleared in six eyes, though two required a second sclerostomy for success. In two of the remaining three eyes the intraocular pressure did not fall to normal levels, but the cornea cleared sufficiently to permit goniotomy, which was successful in each case. The remaining eye failed to respond to two sclerostomies. Thermal sclerostomy is recommended as a primary form of treatment in cases of congenital glaucoma in which corneal opacification makes goniotomy unsafe. While trabeculotomy is useful in these circumstances and may be the procedure of choice in many cases, thermal sclerostomy is recommended for the surgeon who is more familiar with this technique and for cases in which distortion of the anterior chamber angle is expected to preclude trabeculotomy or goniotomy.

Cataract↗
PubMed1997

Transconjunctival application of mitomycin C in combination with laser sclerostomy ab interno: a long-term morphological study of the postoperative healing process.

The precise mechanism whereby mitomycin C enhances IOP reduction in glaucoma filtering surgery still eludes us. Ten rabbits received full-thickness Nd:YAG laser sclerostomy ab interno and adjunctive intraoperative treatment with mitomycin C (MMC) applied topically over the intact conjunctiva (0.5 mg ml-1 for 5 min). A systematic ultrastructural analysis of the fistulas and surrounding tissue was then conducted in conjunction with clinical observations, over the ensuing 10 weeks. In order to investigate also the extent to which MMC impedes fistula occlusion in the absence of percolating aqueous humour, we created non-perforating ('half-thickness') sclerostomies ab interno in three additional rabbits, one with and two without MMC therapy. Transconjunctival MMC application resulted in no serious complications. Eight of the ten full-thickness fistulas remained patent throughout the study, maintaining significant IOP reduction; the other two sclerostomies were compromised by iris incarceration. The MMC-treated, half-thickness canal remained as a tissue-free cul de sac; the two non-treated ones became completely occluded within one week without having recourse to extraocular cell populations. MMC suppressed the migration and proliferation of fibroblasts, macrophages and clump cells from the episclera, sclera, ciliary body and iris root. Repolymerization of heat-damaged collagen was abortive; neosynthesis was not observed. Myofibroblasts were encountered in the vicinity of the sclerostomy canals, and, after the fifth week, these cells were also found to be deployed as a canal-lining layer, delimiting the lumen from the surrounding stroma along most of the fistula length. Towards the external ostium, this layer of myofibroblasts was incomplete or absent. Near the internal ostium, lining cells were derived from the corneal endothelium. The transconjunctival mode of applying MMC appears to be efficient. This antifibrotic drug exerts its inhibitory influence by suppressing not only cell migration and proliferation, but also phagocytic and synthetic activities. However, exposed tissues are not acellular, and amongst the populations present, myofibroblasts are found to dominate the scene. The canal-delimiting cellular lining may play a role in maintaining fistula patency in MMC-treated eyes.

Administration, Topical↗
PubMed1991

Subconjunctival THC:YAG laser thermal sclerostomy.

A THC:YAG laser (thulium, holmium, chromium-doped YAG crystal) was used to create thermal sclerostomies in 21 glaucomatous eyes of 19 patients. The laser is a long-pulsed (300 microsec), compact, self-contained, solid state laser operating in the near infrared (2.1 mu). A 1-mm conjunctival stab incision was made 12 mm away from the sclerostomy site to allow entry of a specially designed 22-gauge (712 mu) optic probe that delivers energy at a right angle to the long axis of the fiber. Probe insertion produced minimal disturbance of the conjunctiva. Pulse energies of 80 mJ to 120 mJ were used with a repetition rate of 5 pulses/second. Total energy levels to produce full-thickness sclerostomies ranged from 1.4 to 4.8 J. Subconjunctival 5-fluorouracil injections were administered in 15 eyes. At 3 months the mean intraocular pressure of successful cases (16) was 14 mmHg (range, 9 to 22 mmHg). Of successful cases, the mean intraocular pressure at 6 months was 13 mmHg (range, 2 to 22 mmHg). Five cases failed within the initial 3 months, and 3 additional cases failed by 6 months. The authors conclude that this full-thickness sclerostomy technique may simplify filtering surgery without anterior chamber instrumentation and with minimal conjunctival trauma.

Adult↗
PubMed1996

Extensive detachment of Descemet membrane after holmium laser sclerostomy.

PURPOSE: To describe a corneal complication and its surgical repair after holmium laser sclerostomy. METHOD: A 63-year-old woman had extensive detachment of Descemet membrane 3 months after holmium laser sclerostomy. The authors describe the case history of a detached Descemet membrane secondary to holmium laser sclerostomy and its subsequent repair. RESULTS: The patient achieved a visual acuity of 20/20 in the involved eye after descemetopexy with sodium hyaluronate and air combined with suturing. CONCLUSIONS: Detachment of the Descemet membrane should be recognized as a potential complication of holmium laser sclerostomy. Suturing should be considered as a method of repair if there is not spontaneous reattachment of the Descemet membrane.

Corneal Diseases↗