Combined Argon and Yag Laser Puppiloplasty: A Case Report

Background: This case portrays different laser utilities in ophtalmic field, the selection of lasers is based on tissue absorption properties and the desired tissue damage outcomes. Different laser types, such as the excimer laser, are utilized for various corneal surgeries, including refractive procedures and phototherapeutic keratectomy for treating corneal disorders. In iridotomy procedures, argon, Nd: YAG, or diode lasers are used to address primary angle closure glaucoma and other related conditions. Iridoplasty, employing the argon laser, aims to open closed angles by inducing iris stroma contraction. Additionally, gentle light impacts and precise laser settings can help separate posterior synechiae without causing lens burns, although pigment clusters may persist on the lens surface.

Case Presentation: This is a descriptive study of one caucasian patient whom medical’s conditions were all treated by different laser technologies.

Conclusion: This study can help understanding the applications and capabilities of different lasers is essential for successful ophthalmic procedures.

Introduction

Choosing an ophthalmic laser relies on the target tissue’s absorption properties and the intended tissue damage, such as thermal photocoagulation, photoablation, or photochemical processes.

The excimer laser is widely used in corneal surgery, particularly for refractive procedures. It has also been employed in phototherapeutic keratectomy for treating corneal disorders affecting the epithelium or anterior stroma, such as recurrent erosion syndrome, corneal dystrophies, keratopathies, scars, and pterygia. Refractive surgery for myopia, myopic astigmatism, and hyperopia has gained popularity due to its precision and commercial success. The excimer laser can reshape the cornea with an accuracy of up to 0.5 micrometers and minimal collateral damage [2]. Photorefractive keratectomy (PRK), which uses the excimer laser to flatten the anterior corneal curvature, was the first refractive technique described [3].

For iridotomy procedures, argon, Nd: YAG, or diode lasers are commonly used to treat primary angle-closure glaucoma, plateau iris, secondary pupillary block glaucoma, malignant glaucoma, and cases where pupillary block obstructs visualization of the trabecular meshwork. The argon laser provides better coagulative effects and reduced bleeding, but the Q-switched Nd: YAG laser, which causes tissue photodisruption regardless of pigment, has higher efficiency and improved long-term results [4], [5].

Iridoplasty employs an argon laser to open appositionally closed angles by applying contraction burns of long duration, low power, and large spot size on the extreme iris periphery. This causes the iris stroma to contract and separate from the angle, thus mechanically opening it. Iridoplasty can also be utilized before trabeculoplasty to enhance the visualization of the trabecular meshwork [6], [7].

Posterior synechiae can often be separated by applying a series of gentle light impacts on the adherent pigment epithelium near the edge of the pupil. Recommended settings include 0.01 seconds, 300 to 500 mW, and a 50-micron spot, often with the aid of lenses such as the Abraham or CGI lens. With careful technique and low power settings, synechiae can be separated without causing lens to burn [8]. However, pigment clusters may remain on the lens surface, which can later absorb laser energy intended for the retina.

Materials and Methods

Patients Information

This is a descriptive study of one 46-year-old Caucasian male patient whom primary concers were his malignant glaucoma, his corneal dystrophy and posterior iris synechia. The patient’s medical conditions were all treated by different laser technologies in 2023 at the ophthalmology department of the Mohamed VI International University Hospital. We used ARGON Laser, YAG Laser and Excimer Laser. The objective of the study was to describe the multifunction of different types of lasers in ophtalmology.

Clinical Findings

The clinical examination of our 38-year-old Caucasian patient found a right-eye visual acuity was 3/10, and in the left eye, counting fingers at one meter. Slit-lamp biomicroscopy revealed left-eye posterior synechiae, resulting in a “tomato iris” appearance, and a corneal lattice dystrophy in the right-eye.

Diagnostic Assessment

1. Diagnostic Methods

The following diagnostic methods were employed to ensure accurate assessment and differentiation from similar conditions:

• Physical Examination (PE):

– Visual Acuity Testing: Right eye (3/10), Left eye (counting fingers at 1 meter).

– Slit-Lamp Biomicroscopy: Revealed corneal lattice dystrophy in the right eye (Fig. 1) and posterior synechiae in the left eye, leading to a “tomato iris” appearance.

Fig. 1. Slit lamp image of the patient’s right eye showing a corneal lattice dystrophy before treatment.

• Imaging:

– Slit-Lamp Photography: Captured images of both eyes before and after laser treatments to assess corneal and iris conditions.

• Laboratory Testing:

– No specific laboratory tests were mentioned in this case, as most of the diagnostics were based on imaging and clinical observation.

• Surveys:

– No surveys were mentioned as part of the diagnostic process.

2. Diagnostic Challenges (As mentioned in Table I)

Table I. Timeline of Ophthalmic Care Episode

Date	Event/Procedure	Details	Outcome/Notes
November 2021	Diagnosis of Multiple Conditions	The 38-year-old Caucasian male patient was diagnosed with malignant glaucoma, corneal lattice dystrophy, and posterior synechiae.	- Right eye visual acuity: 3/10- Left eye: counting fingers at 1 meter- Slit-lamp biomicroscopy revealed left-eye posterior synechiae (“tomato iris Fig. 2”) and right-eye corneal dystrophy.
August 2022	Iridotomy with YAG & Argon Lasers	Topical oxybuprocaine applied. YAG laser (4 mJ energy) and Argon laser (0.02 s, 50 μm spot size, 500–700 mW power) used for iridotomy.	Iridotomy performed on the left eye to manage intraocular pressure and address glaucoma.
September 2022	Synechiotomy with Lasers	Same YAG and Argon lasers were used for synechiotomy (0.02 s, 50 μm, 400–500 mW power).	Synechiotomy performed to release posterior synechiae in the left eye (Fig. 4).
October 2022	Pupilloplasty with Argon Laser	Argon laser applied (0.2 s, 200 μm spot size, 200–400 mW power).	Pupilloplasty performed to further treat iris abnormalities and improve pupil shape (Fig. 4).
November 2023	Phototherapeutic Keratectomy (PTK)	PTK performed on the right eye using the excimer laser (7 mm diameter, 60 μm depth) for corneal dystrophy.	Treated corneal dystrophy in the right eye.
November 2023	Photorefractive Keratectomy (PRK)	PRK was performed on the right eye for -3D myopia (6.5 mm optical zone, 521 μm pachymetry, 400 μm residual stroma) with mitomycin applied (0.02 mg for 50 seconds).	Corrected refractive error (myopia) in the right eye.
Post-procedure (December 2023)	Intraocular Pressure Spike & Hyphema	Intraocular pressure increased from 17 mmHg to 28 mmHg post-procedure. Hyphema occurred.	Treated with dexamethasone drops, dorzolamide-timolol combination, and phenylephrine.

Fig. 2. Slit lamp image of the patient’s left eye showing a “tomato iris” appearance before treatment.

Several factors posed challenges in reaching a definitive diagnosis, necessitating a comprehensive evaluation approach:

• Dense Posterior Synechiae: The presence of posterior synechiae, where the iris adhered to the lens, made the visual examination and treatment more complex, especially due to the “tomato iris” appearance (Fig. 2)

• Corneal Lattice Dystrophy: Diagnosis and treatment were complicated by the corneal dystrophy, requiring precise laser use (PTK).

• Elevated Intraocular Pressure (IOP): After laser procedures, an IOP spike and hyphema occurred, complicating the post-procedural management.

• Visualization Issues: Laser iridotomy procedures can be challenging due to poor visualization through corneal edema or synechiae. Corneal haze or endothelial burns may also limit imaging and diagnostic precision (Fig. 1).

3. Diagnosis (Including Differential Diagnoses Considered)

The diagnosis was established based on clinical findings and imaging techniques as follows:

• Primary Diagnoses:

– Malignant Glaucoma: Diagnosed based on symptoms of elevated IOP and posterior synechiae.

– Posterior Synechiae: Identified via slit-lamp biomicroscopy in the left eye (Fig. 2).

– Corneal Lattice Dystrophy: Diagnosed based on visual signs observed in the slit-lamp examination of the right eye (Fig. 1).

• Differential Diagnoses Considered:

– Pupillary Block Glaucoma: Ruled out as a primary diagnosis since it was treated with laser iridotomy, but malignant glaucoma persisted.

– Keratoconus: Considered as a differential due to corneal abnormalities but slit-lamp findings confirmed lattice dystrophy instead.

4. Prognostic Characteristics

The prognostic characteristics were determined by evaluating overall patient outcomes as follows:

• Visual Prognosis: Prognosis for visual improvement depends on the successful resolution of synechiae and corneal dystrophy. PRK and PTK were expected to provide visual correction, especially for the right eye.

• Intraocular Pressure Management: The patient’s IOP may need long-term monitoring due to the risk of recurring spikes, even after successful iridotomy.

• Complication Risks: Post-laser hyphema and elevated IOP highlight the potential for further complications. Careful follow-up will be needed to manage these risks.

• Long-term Outlook: If the lattice dystrophy is effectively managed with PTK and the IOP stabilizes after iridotomy, the long-term visual outcomes can be favorable. However, further intervention may be necessary if complications arise.

Results

Therapeutic Intervention (Table I)

Topical oxybuprocaine chlorhydrate was applied before placing the Abraham iridectomy lens. Both a YAG laser (4 mJ energy) and an Argon laser (0.02 s exposure, 50 μm spot size, 500–700 mW power) were utilized. The same lasers were employed for synechiotomy with adjusted settings (0.02 s exposure, 50 μm spot size, 400–500 mW power, 4 mJ YAG energy). Pupilloplasty was performed using an Argon laser (0.2 s exposure, 200 μm spot size, 200–400 mW power) (Fig. 3).

Fig. 3. Slit lamp image of the patient’s left eye after treatment.

Fig. 4. Slit lamp image of the patient’s right eye after treatment.

Follow-Up and Outcomes (Table I)

Post-procedure, intraocular pressure increased from 17 mmHg to 28 mmHg, and hyphema occurred. Treatment included dexamethasone drops, a dorzolamide-timolol combination, and phenylephrine. The right eye underwent phototherapeutic keratectomy (PTK) for lattice corneal dystrophy (7 mm diameter, 60 μm epithelial depth) and photorefractive keratectomy (PRK) for -3D myopia (6.5 mm optical zone, 521 μm pachymetry, 400 μm residual stroma, applying diluted mitomycin at 0,02 mg for 50 seconds) (Fig. 4).

Discussion

Long-duration laser iridotomy techniques, lasting 0.10 seconds or more, often result in complications such as iritis, pupil distortion, and inadequate penetration [1], [2]. There have been instances of macular and retinal burns, possibly due to the high energy used in each burn, reaching up to 1000 millijoules. These extended techniques tend to be ineffective on thick brown irises commonly found in individuals of African or Asian descent. Such irises can become dense and resistant to penetration as they shrink, char, and thicken [3]. On the other hand, shorter-duration techniques, lasting 0.01 to 0.02 seconds, can penetrate these irises but typically require a significant number of laser burns, approximately 600 or more, to create a properly sized iridotomy using the traditional chipping method [4].

To address this issue, a modified short-duration technique called linear incision has been developed, allowing for reliable penetration of these irises with only a fraction of the burns needed in traditional methods [5]. A challenge often encountered in laser iridotomy for thick irises in individuals of Asian or African descent is the presence of a white fibrous layer deep within the iris, which resists further penetration. The linear incision technique facilitates easier penetration of this fibrous barrier compared to other methods by inducing tension in the deeper layers while cutting the superficial layers linearly [6].

Blue irises, which tend to reflect the laser, can also pose challenges for laser iridotomy. However, the linear incision method has demonstrated success in creating large iridotomies in all blue eyes treated so far, potentially reducing the reliance on the Nd:YAG laser, which carries a risk of damaging the lens capsule [7].

Understanding the tension lines in the iris and identifying areas of varying thickness can aid in determining the appropriate locations for laser incisions. Making linear cuts across the fibers of the iris creates radial tension that can enlarge the iridotomy [8].

The ideal location for laser iridotomy is approximately two-thirds of the distance from the margin of the pupil to the limbus. Other laser iridotomy techniques may fail due to heat transmission in the shallow peripheral anterior chamber, leading to corneal endothelial burns and haze. However, the linear incision technique seldom causes corneal burns, even in cases with very shallow anterior chambers, as it generates minimal thermal energy per burn. Lens burns are unlikely unless excessive power levels hit the pigmented layer adjacent to the lens [9].

When it comes to reducing intraocular pressure (IOP), conventional methods involve using topical and systemic medications to resolve corneal edema caused by high IOP. These medications can also alleviate pupil blockage, typically through laser peripheral iridotomy, which is a definitive treatment. However, elevated IOP levels can result in ischemia-induced iris sector atrophy, releasing pigment and causing pigmentary dusting on the iris surface and corneal endothelium. Iris sphincter muscle ischemia can also permanently fix and dilate the pupil, rendering medications ineffective and potentially worsening factors contributing to pupillary blockage [9], [10].

To prevent another acute attack, surgical iridectomy or, more commonly, laser peripheral iridotomy should be performed once the attack is under control and the cornea has sufficient clarity. Laser peripheral iridotomy is a preferred non-invasive therapeutic solution for acute primary angle-closure (APAC) due to its ease of execution. This surgical approach creates a connection between the anterior and posterior chambers, reducing pupil blockage. However, corneal edema can impede visibility of the anterior chamber, making laser peripheral iridotomy challenging and increasing [11], [12].

Conclusion

In conclusion, laser iridotomy techniques play a crucial role in addressing various challenges associated with iris characteristics and intraocular pressure management. While long-burn methods have been found to result in complications and limited effectiveness, short-burn techniques offer better penetration but often require a high number of laser burns. The development of the linear incision technique has shown promising results, allowing for reliable penetration of thick irises with fewer burns compared to traditional methods. This approach also demonstrates success in creating large iridotomies in blue irises, potentially reducing reliance on riskier procedures. Understanding iris tension lines and selecting optimal locations for laser incisions are vital for achieving desired outcomes. Additionally, laser peripheral iridotomy remains an effective non-invasive treatment for acute primary angle-closure, although corneal edema can pose challenges. As advancements continue, emerging strategies like iridoplasty, pupilloplasty, and anterior chamber paracentesis offer alternative approaches to lowering intraocular pressure. Combining these techniques may prove valuable in managing complex cases. It is essential to consider individual factors and customize treatment plans to ensure optimal outcomes in laser iridotomy procedures and intraocular pressure management overall.