Nd-YAG Laser Iridotomy Research Articles

Effects of Nd-YAG Laser iridotomy on anterior segment measurements in pigment dispersion syndrome and ocular hypertension

To compare the anterior segment optical coherence tomography (AS-OCT) measurements of eyes with pigment dispersion syndrome (PDS) and ocular hypertension (OHT) before and after neodymium:yttrium-aluminum-garnet (Nd:YAG) laser peripheral iridotomy (LPI). A total of 23 eyes of 23 patients with PDS and OHT with features of PDS were included in this retrospective study. All of the eyes with PDS and OHT were examined by AS-OCT before and after Nd:YAG LPI. Anterior chamber depth, angle opening distance 500, angle opening distance 750, trabecular iris space 500, trabecular iris space 750 and scleral spur angle, iris bowing and iris shape were measured with AS-OCT by the same examiner. The differences in all parameters before and after Nd:YAG LPI were statistically significant. Iris configuration was concave in all eyes prior to iridotomy. After Nd:YAG laser iridotomy, the iris configuration became convex in 7 eyes, flat in 9 eyes and remained concave in 7 eyes. Nd:YAG laser peripheral iridotomy is an effective method for reversing the iris concavity and iris bowing in pigment dispersion syndrome.

Descemet’s Membrane Injury Post YAG Peripheral Iridotomy

Neodymium: Yittrium - Aluminium-Garnet (Nd YAG) laser iridotomy is one of the most common laser procedures performed in the Asian continent as the proportion of Angle closure glaucoma cases is significant. The Nd YAG iridotomy appears to be a simple outpatient procedure but can result in a number of complications including haemorrhage, cataract formation, dysphotopsia, intraocular pressure elevation and corneal endothelial damage resulting in corneal decompensation at a later date. A forty one year old female patient, a case of Primary Angle Closure Suspect (PACS), who had undergone a Nd YAG laser iridotomy of both the eyes elsewhere presented to us for a second opinion. The anterior segment examination was unremarkable except for the bilateral peripheral Iridotomies. The slit lamp examination revealed three small defects in the temporal cornea at the level of the Descemet’s membrane and posterior stroma overlying the iridotomy in the right eye. A specular microscopy did not reveal any endothelial damage or change in the cell morphology overlying the iridotomy or in other areas. Anterior segment Ocular Coherence Tomography (OCT) demonstrated the exact nature of the injury to the Decemets membrane. To the best of our knowledge, its the first case report in the literature of a Descmet’s membrane injury following a ND-YAG laser iridotomy. It emphasizes the importance of accurate focus on the iris and choosing a quadrant with adequate distance between the iris and the cornea to avoid injury to surrounding structures.

Long-Term Intraocular Pressure Control After Nd-YAG Laser Iridotomy in Chronic Angle-Closure Glaucoma

To evaluate the long-term results of Nd-YAG laser iridotomy, a retrospective study was undertaken of 52 consecutive patients (78 eyes) who had chronic angle-closure glaucoma and who had undergone Nd-YAG laser iridotomy. After a mean follow-up of 22 months, the intraocular pressure was <22 mm Hg without additional treatment in 7 eyes (9%) and with glaucoma medication in 40 eyes (51.3%). At the last follow-up visit, the intraocular pressure was between 22 and 24 mm Hg with an average of two medications in eight eyes (10.2%). Trabeculectomy was required in 23 eyes (29.5%). Those eyes with an intraocular pressure on presentation of >35 mm Hg, or with three or more quadrants of angle closure or with a cup:disc ratio of >0.6, were more likely to undergo trabeculectomy. However, linear discriminant analysis of the ocular findings on presentation revealed that those eyes that underwent trabeculectomy could only have been predicted in 78% and that 36% of eyes identified as being at risk that were subsequently controlled with or without glaucoma medication would have undergone unnecessary trabeculectomy (prediction accuracy: 57%). This study confirms that the current practice of Nd-YAG laser iridotomy, followed if necessary by medical therapy and trabeculectomy, is effective in the management of chronic angle-closure glaucoma. However, careful follow-up of intraocular pressure control and visual field performance is required in patients with advanced disease.

Effect of Carteolol on Intraocular Pressure Elevation Following Laser Iridotomy

Abstract With the advent of laser application in ophthalmology, iridotomy has become a well-accepted routine procedure for angle closure glaucoma. However, spike elevation of intraocular pressure (IOP) after laser procedure, especially in those severely compromised eyes, remains to be overcome by laser surgeons. In the past year, argon and Nd-YAG laser iridotomy was performed on 434 eyes of 274 patients with primary angle closure glaucoma. The patients were divided into four groups to evaluate the hypotensive effect of carteolol. Group I was pretreated with pilocarpine, Group II with pilocarpine and acetazolamide, Group III with pilocarpine and carteolol, and Group IV with pilocarpine, acetazolamide, and carteolol. In the group treated with carteolol and acetazolamide, the post-laser IOP elevation is significantly less than in the other groups. The difference is especially significant for the Nd-YAG laser group. The 2-hour postlaser IOP elevation is positively correlated with the prelaser IOP, while no su...

How large must an iridotomy be?

Four cases of acute angle closure glaucoma in eyes with a small but patent Nd-YAG laser iridotomy are presented, and similar cases in the literature are reviewed. Theoretically a 15 microns diameter iridotomy should be large enough to prevent angle closure glaucoma due to pupil block. Mechanisms by which larger iridotomies fail to prevent angle closure glaucoma, and the role of provocation tests following iridotomy, are discussed. An iridotomy should be at least 150-200 microns in diameter if acute angle closure glaucoma is to be reliably prevented.

Acute closed-angle glaucoma and Nd-YAG laser iridotomy.

Forty-one patients presenting consecutively with acute angle closure glaucoma (AACG) were studied with a median follow-up period of eight months. Four patients presented with bilateral symptoms. Thirty-nine patients underwent Nd-YAG laser iridotomy (42 AACG eyes and 36 fellow eyes). Only 15 patients (36.6%) required simply iridotomy; the remainder required additional long term medical or surgical treatment. Longer duration of symptoms and a history of previous intermittent, spontaneously resolved AACG were more common in those requiring additional treatment. Cataract extraction with intraocular lens implantation was performed for three eyes with AACG, and this mode of treatment is discussed as a possible primary treatment. One eye with AACG suffered a second episode, and two fellow eyes developed AACG despite laser iridotomy. Possible mechanisms are discussed. Provocative testing or frequent careful observation of iridotomy patency is recommended.

Efficacy of Nd-YAG laser iridotomies in acute angle closure glaucoma.

Between September 1984 and April 1987 a total of 150 patients underwent Nd-YAG laser iridotomy procedures at the Bristol Eye Hospital. Forty of these patients (27%) were treated for acute angle closure glaucoma (AACG), and three of them (7%) suffered recurrent AACG. Sixteen patients who had been treated for AACG have been challenged by a pharmacological provocative test introduced by Mapstone, with a total of 23 eyes being tested. A negative result was obtained in all cases. Provocative testing is recommended to help identify those at risk of recurrent AACG.

Experiences with laser therapy in different forms of glaucoma with open and closed chamber angle

Results of laser treatment of open-angle and angle-closure glaucomas are communicated. Argon laser trabeculoplasty was performed in 78 eyes with open-angle glaucoma. The most favorable site for photocoagulation was the gone between the pigmented and nonpigmented trabecular meshwork. Forty-two eyes with angle-closure glaucoma were treated by argon laser gonioplasty. This method proved successful in chronic angle-closure glaucoma and for the prophylactic management of acute angle-closure glaucomas. A combination of argon laser gonioplasty and argon laser trabeculoplasty was used in 16 eyes. Both methods were found to be effective in treating certain forms of juvenile glaucoma. A further 11 eyes with acute angle-closure glaucoma were treated by Nd-YAG laser iridotomy, 9 of them successfully.

Long-term results of Nd-YAG laser iridotomy and indications deriving from it

Of 132 patients who had undergone Nd-YAG laser iridotomy, 70 were randomly selected for follow-up examinations. Nd-YAG laser iridotomies were subsequently performed on 124 eyes (of these 70 patients), 12 for acute angle-closure glaucoma, 19 fellow eyes of those which had angle-closure glaucoma, 70 for chronic angle-closure glaucoma, and 23 eyes with increasingly narrow chamber angle under miotic therapy. The follow-up period ranged from 1 to 25 months (median = 9 months). Eighty-seven percent of the iridotomies remained visibly open. Of 12 acute glaucomas, 10 were successfully treated, whereas only 2 required a basal iridectomy. In the large group of 106 eyes with a "narrow angle condition," a significant pressure reduction from 20.9 +/- 5.8 to 16.7 +/- 3.4 mm Hg and a significant enlargement of the chamber angle resulted. Since fistulizing procedures involve a risk of malignant glaucoma, Nd-YAG laser iridotomy, which this investigation showed to be risk-free, is the initial procedure of choice in narrow-angle conditions, especially subacute and chronic angle-closure glaucoma, in order to alleviate the angle-closure component in such angle-closure situations, to diagnose its contribution to peak IOP, and to facilitate argon laser trabeculoplasty when needed.

Fluorophotometrie als Methode zum Nachweis von Permeabilitätsänderungen der Blut-Kammerwasser-Schranke

The increase in permeability of the blood-aqueous barrier after Nd-YAG laser iridotomy and the protective effect of locally applied indomethacin were investigated in an experimental animal study using a computerized fluorophotometer. The permeability of the blood-aqueous barrier was evaluated by three different molecules: fluorescein-sodium (molecular weight 330), fluorescein-labeled dextran 70 000 (molecular weight 70 000) and fluorescein-labeled dextran 150 000 (molecular weight 150 000). The fluorescein concentration of the anterior chamber was measured in 36 eyes (18 rabbits) as well as in a control group of 9 eyes (9 rabbits) at fixed times after intravenous dye injection. Fluorescein leakage occurred, but no leakage of fluorescein-labeled dextrans was visible in the control group. Laser iridotomy induced a time-dependent increase in anterior segment permeability to fluorescein and fluorescein-labeled dextrans. Disturbance of the blood-aqueous barrier was effectively reduced by topical pretreatment with indomethacin, which mainly inhibited the leakage of the fluorescein-labeled dextrans. The clinical relevance of the laser-induced breakdown of the blood-aqueous barrier and the protective effect of a prophylactic pharmacotherapy are discussed.