OCULUS GONIO ready ®

 

The OCULUS GONIO ready ® is a microscope attachment developed by Oculus, that enables the surgeon to perform MIGS procedures easily with both hands.

Currently, the surgeon has to hold the gonio-lens with one hand when performing MIGS procedures.

With this device, the surgeon is free to use both hands and have a bimanual approach when performing glaucoma surgeries.

It is possible to use this attachment with a number of microscopes. The list of compatible microscopes is available at the OCULUS GONIO ready ® website.

https://www.oculussurgical.com/gonioready?utm_campaign=GONIO_ready&utm_source=bmc.glaucoma_today&utm_content=GONIO_ready&utm_medium=sticky_banner.website

The device is for single-use only, overcoming the hassle of sterilization of the gonio-lenses and providing excellent optical quality consistently.

The device is small, yet provides impeccable depth of field and a large field of view (180-degrees), thus, improving the peripheral awareness.

Due to small size of the device, it can be used in pediatric patients also.

The device has a patented Flex System, a flexible “swan neck”, which enables surgeons to allow the lens to float atop the cornea, reducing image distortion and offering better access to corneal incisions for any MIGS device.

This system avoids creating any additional pressure against the patient’s eye, ensuring a more comfortable and relaxing patient experience. Additionally, the Flex System is flexible enough to be moved around during MIGS but is sufficiently resistant to movement so as not to be inadvertently displaced, thus offering consistent, repeatable, and stable lens positioning throughout the procedure.

The device is specifically designed to optimize performance with either a f = 175 mm or f = 200 mm microscope objective lens: 

• 10011226: GONIO ready® 175, for f = 175 mm
• 10008420: GONIO ready® 200, for f = 200 mm

 

THE GONIO SCRATCH STUDY

 

The mechanism of IOP elevation in primary open-angle glaucoma (POAG) remains unclear. 

The greatest resistance to aqueous humor outflow occurs in the juxtacanalicular tissue and the inner wall of Schlemm’s canal. 

There is accumulation of extracellular matrix and a substance called plaque material in the juxtacanalicular tissue of the trabecular meshwork in POAG patients. This is thought to result in increased resistance to aqueous outflow through the meshwork.

Gonio scratch is a surgical procedure that improves aqueous humor outflow by rubbing off deposits on the trabecular meshwork with a Diamond Dusted Sweeper. 

The Diamond Dusted Sweeper (DORC, Zuidland, Netherlands) is a diamond-dusted silicone-tipped manipulator. It was developed by Tano et al in 1997 to remove the epiretinal membrane during vitrectomy. 

As the conjunctiva and trabecular meshwork are not incised, fewer complications and shorter operative times are expected with no postoperative bleeding, and minimal IOP spikes. 

When combined with cataract surgery, gonio scratch is performed after the intraocular lens is inserted.

The Diamond Dusted Sweeper is used to scratch the trabecular meshwork to remove deposits in this region. This is performed over 120 degrees of the trabecular meshwork, and the region is scrubbed two to three times by the duster. [1]

The authors have reported the one-year findings of the Gonio Scratch Study. Forty-seven eyes of 47 patients underwent GS-Phaco surgery. 

The median baseline IOP was 17 mm Hg. At 12 months postoperatively, there was a significant reduction in IOP to a median of 12 mm Hg ( P <0.01). The number of glaucoma medications also decreased significantly, from a median of 2 to 1 ( P <0.01). The surgical success rate at 12 months was 80.9%. The only complication observed was transient elevation of IOP in 2 (4.3%) eyes. No patient developed hyphema.

The authors concluded that GS-Phaco achieved sustained IOP reduction and a decrease in medication use at 12 months postoperatively in patients with POAG and cataracts. [2]

FOLLOW LINK FOR A PRIMER ON GONIOSCOPY:

https://touchophthalmology.com/glaucoma/journal-articles/gonioscopy-a-primer/

REFERENCES:

1. Tokumo K, Okada N, Mochizuki T, Onoe H, Komatsu K, Okumichi H, Hirooka K, Mochizuki H, Yokoyama M, Kiuchi Y. The gonio scratch study: methodology of a multicenter clinical trial establishing a new minimally invasive glaucoma surgery. Nagoya J Med Sci. 2024 Feb;86(1):36-42. 
2. Tokumo K, Yokoyama M, Baba T, Okada N, Edo A, Komatsu K, Okumichi H, Mochizuki H, Miyoshi T, Kiuchi Y, Hirooka K. One-Year Outcomes of Gonio Scratch as a Minimally Invasive Glaucoma Surgery With Cataract Removal. J Glaucoma. 2025 Jun 1;34(6):468-475. 

VIALUXE LASER SYSTEM & FLigHT STUDY

 

The ViaLuxe™ Laser System is designed to reduce IOP, using a micron resolution OCT image-guided femtosecond laser, to non-invasively create customized drainage channels through the trabecular meshwork.

https://www.vialase.com/

ViaLuxe Laser System

The machine has the following features =

1. ViaLens Patient Interface:

Non-invasively provides unmatched view and delivery of the femtosecond laser into the trabecular meshwork angle.

2. ViaVue Gonio Camera:

Gonio imaging enables the view of complete structures of the angle in all four quadrants.

3. ViaLuxe Laser:

Precisely creates channels without collateral damage to adjacent tissues.

4. ViaLink:

Bluetooth-connected tablet displays real-time procedure data and diagnostics.

 FLigHT STUDY:

ViaLase, Inc, announced the online publication of 24-month safety data from the first-in-human study of femtosecond laser image-guided high-precision trabeculotomy (FLigHT) performed with the ViaLase technology in Ophthalmology Science, a journal of the American Academy of Ophthalmology.

The investigators in this prospective, non-randomized, single-center, interventional, single-arm trial evaluated 11 patients (17 eyes) with open-angle glaucoma following FLigHT treatment, which consisted of the creation of a single channel through the trabecular meshwork and into Schlemm’s canal. At 24 months post-treatment, the authors reported no device-related serious adverse events and observed well-defined channels with no evidence of closure, indicating medium-term durability.

The study data demonstrated a mean IOP reduction of 34.6% from a baseline of 22.3 ± 5.5 to 14.5 ± 2.6 mmHg at 24 months.

 

GONIOSCOPY: MADE EASY
(REVISED)

Alexios Trantas, in 1907, first used the term“gonioscopy”, from the Greek origins on gonia meaning “angle” and skopein to “observe”. Maximilian Salzmann was the first to use a contact lens and indirect gonioscopy for examination of the angle. Therefore, both Trantas and Salzmann are regarded as the “fathers of gonioscopy”.

Principle of gonioscopy:

When light passes from a medium with greater index of refraction to a medium with lower index of refraction, the angle of refraction (r) is greater than the angle of incidence (i).

The angle of incidence (i) reaches critical angle when r is equal to 90⁰.

If the angle of incidence (i) is more than critical angle, the light is reflected back into the first medium. (Total internal reflection)

The critical angle for the cornea-air interface is approximately 40⁰.

Light rays coming from the angle of the anterior chamber exceed the critical angle and are therefore reflected back into the AC (anterior chamber). This prevents visualization of the AC angle.

This deficiency can be overcome by optically replacing the cornea with another interface.

The refractive index of the contact lens is the same as that of the corneal epithelium so that there is minimal refraction at the interface of these 2 surfaces (Contact lens-cornea). This removes the optical effect of cornea.

The light rays from the AC angle reach the contact lens. Subsequently, they are made to pass through the new "contact lens-air" interface.

In direct gonioscopy (gonio-lens) the anterior curve of the contact lens is such that the critical angle is not reached. The light rays are refracted at the contact lens-air interface to the observer’s eye.

In indirect gonioscopy, the light rays are reflected by a mirror in the contact lens (gonio-prism). The light rays leave the lens at nearly a right angle to the contact lens-air interface.

INDIRECT GONIOSCOPY:

Goldmann single-mirror contact lens	Mirror height= 12mm	Mirror tilt= 620
Goldmann 3-mirror	Semicircular mirror	590
Zeiss 4-mirror		640
Ritch trabeculoplasty 4-mirror lens		2 tilted= 590 2 tilted= 620

Procedure:

• Use minimal room illumination.
• Shorten slit beam as much as possible. Do not throw light into the pupil.
• Use high magnification.
• Keep beam off-centre at 30-35⁰.
• Place lens gently on the eye with patient looking up. Once the lens is in place ask patient to look straight.
• Stop moving the lens when you can view the iris. (Furrows)
•  

From Kanski

Now move the beam towards the periphery. In myopes, aphakia/pseudophakia you can see the ciliary body. It appears as a pink, dull brown or slate grey band.

The scleral spur is the posterior lip of the scleral sulcus. It appears as a prominent white line between the dark ciliary body band and the pigmented trabecular meshwork.

Fine, pigmented strands frequently cross the scleral spur. They run from the iris root to the pigmented trabecular meshwork and are called “iris processes”. (They represent thickenings of the posterior uveal meshwork).They might be confused with peripheral anterior synechiae and need dynamic gonioscopy for confirmation.

Anterior to the scleral spur is the functional trabecular meshwork. It is seen as a pigmented band just anterior to the scleral spur.

The junction of the angle structures and cornea is called Schwalbe’s line. It is the peripheral termination of Descemet’s membrane. It appears as a fine ridge or opaque line. In highly pigmented eyes, it can be pigmented, especially inferiorly.

GRADES OF ANGLE WIDTH:

 (Modified from Clinical Ophthalmology: A systemic approach, Jack J Kanski, 6th ed.)

GRADE 4	350-450	Ciliary body visible.	Seen in myopia, aphakia, pseudophakia.	Incapable of closure.
GRADE 3	250-350	Scleral spur visible.		Incapable of closure.
GRADE 2	200	Trabecular meshwork visible.	Moderately narrow angle.	Angle closure possible but unlikely.
GRADE 1	100	Schwalbe’s line visible.	Very narrow angle.	Angle closure not inevitable, but risk is high.
SLIT ANGLE		No obvious irido-corneal contact. However, no angle structures can be identified.		High risk of imminent closure.
GRADE 0	00	Iridocorneal contact present. Inability to identify the apex of corneal wedge.	Closed angle.	Indentation gonioscopy is required to differentiate appositional from synechial angle closure.

Dynamic Gonioscopy (Compression or indentation gonioscopy):

• Pressure is applied on the cornea with contact lens, this pushes aqueous into the AC angle.
• This opens up the angle.
• In case of peripheral anterior synechiae (synechial closure) the angle may not open but will open up if only iris processes are present or the cornea and angle structures are in close approximation (appositional closure).

GONIOSCOPY FLOW CHART:

Acknowledgment:
Some of the pictures have been taken from: Gonioscopy by Christoph Faschinger & Anton Hommer. Springer publications.