Understanding Iridocorneal Endothelial Syndrome and its Impact on Intraocular Pressure

Understanding Iridocorneal Endothelial Syndrome and its Impact on Intraocular Pressure

June 10, 2022

Iridocorneal Endothelial Syndrome (ICES) stands as a complex eye disorder, intricately influencing the delicate balance of the iridocorneal endothelium. This syndrome has profound implications for Intraocular Pressure (IOP), demanding a closer look at its manifestations and potential complications.

How Iridocorneal Endothelial Syndrome (ICES) Leads to High Intraocular Pressure

Iridocorneal Endothelial Syndrome (ICES) exerts its influence on intraocular pressure (IOP) through a cascade of intricate mechanisms that affect the normal physiology of the eye. Understanding these mechanisms is pivotal for devising effective treatment strategies.

At the core of ICES-induced high IOP is endothelial dysfunction, a condition where the specialized cells lining the inner surface of the cornea fail to maintain their normal function. This dysfunction disrupts the delicate balance of fluid dynamics within the eye, leading to an accumulation of aqueous humor.

The altered behavior of the endothelial cells results in changes to the composition and outflow of aqueous humor, the clear fluid that fills the front part of the eye. This fluid is crucial for maintaining the shape of the eye and nourishing its structures, but in ICES, its regulation is compromised.

One key aspect of this disruption is the impaired drainage of aqueous humor. The trabecular meshwork, responsible for facilitating the outflow of fluid, becomes less efficient in ICES patients. This inefficiency leads to a buildup of pressure within the eye, manifesting as elevated IOP.

Moreover, ICES is often associated with the development of abnormal corneal endothelial cells termed "guttae." These excrescences further impede the natural movement of fluid, contributing to an increase in IOP.

The correlation between ICES and high IOP is also linked to changes in the anterior chamber angle, a critical area where the cornea and iris meet. As the angle undergoes alterations due to the syndrome, it can hinder the outflow of aqueous humor, adding another layer to the complexity of IOP regulation.

Studies have shown that addressing these specific mechanisms is essential for effective management. Therapies targeting the restoration of endothelial function, such as selective laser trabeculoplasty and corneal transplantation, aim to mitigate the impact of ICES on IOP.

In essence, comprehending how ICES leads to high IOP involves deciphering the disruptions in endothelial function, trabecular meshwork efficiency, and the overall fluid dynamics of the anterior chamber. This understanding forms the basis for developing precise interventions that not only alleviate elevated IOP but also address the root cause within the intricate mechanisms of Iridocorneal Endothelial Syndrome.

Identifying High IOP in Iridocorneal Endothelial Syndrome Patients

Recognizing the signs of elevated Intraocular Pressure (IOP) in patients with Iridocorneal Endothelial Syndrome (ICES) is crucial for timely intervention and optimal management. Understanding these indicators and employing precise diagnostic tools are paramount in ensuring comprehensive eye care.

1. Visual Disturbances

Individuals with ICES and high IOP often experience visual disturbances. These may manifest as blurred vision, halos around lights, or even sudden changes in visual acuity. These symptoms are indicative of the impact of increased pressure on the optic nerve and the overall health of the eye.

2. Eye Pain and Discomfort

Elevated IOP in ICES can cause discomfort and pain in the affected eye. Patients may describe aching sensations, pressure, or a feeling of fullness, signaling the stress on ocular structures.

3. Headaches

Persistent headaches, especially around the brow and temple areas, can be associated with increased IOP. These headaches may intensify after activities that involve eye strain, such as reading or prolonged screen time.

4. Redness and Irritation

ICES patients with high IOP may exhibit redness and irritation in the affected eye. This could be attributed to the compromised blood flow and increased pressure affecting the conjunctiva.

5. Changes in the Appearance of the Eye

Swelling or changes in the appearance of the eye may occur due to increased IOP. Additionally, a cloudy appearance in the cornea, caused by endothelial dysfunction, might be observed during a clinical examination.

Diagnostic Approaches

Tonometry: This test measures the pressure inside the eye and is a key diagnostic tool for identifying elevated IOP. Tonometry is crucial in the regular monitoring of ICES patients.

Corneal Pachymetry: Measuring corneal thickness provides insights into the potential impact of elevated IOP. Thinner corneas may indicate a higher risk of complications.

Visual Field Testing: Evaluating the patient's visual field helps identify any peripheral vision loss, a common consequence of elevated IOP affecting the optic nerve.

Gonioscopy: This procedure allows for the visualization of the iridocorneal angle, assisting in assessing the drainage pathways for aqueous humor and identifying potential blockages.

By recognizing these telltale signs and employing precise diagnostic methods, ophthalmologists can initiate targeted interventions to manage high IOP effectively in ICES patients. Timely diagnosis not only preserves vision but also enhances the overall quality of life for individuals grappling with the complexities of Iridocorneal Endothelial Syndrome.

Navigating ICES with a Focus on High IOP

The treatment landscape for ICES, particularly when coupled with high IOP, encompasses a spectrum of options. Medications targeting IOP reduction, surgical interventions like iridotomy, and more complex procedures such as trabeculectomy are tailored to address the nuances of each case. Each modality aims to restore normal aqueous humor dynamics and mitigate the impact on IOP.

Implementing Treatment Strategies for High IOP

Executing treatment strategies for high IOP demands precision. Ophthalmic surgeons utilize techniques like gonioscopy to visualize the iridocorneal angle, ensuring accurate interventions. Procedures like aqueous shunt implantation require meticulous planning to achieve optimal outcomes while minimizing complications.

Case Studies: Real-Life Examples of ICES Treatment with High IOP

When medical therapy is unsuccessful at controlling IOP, surgical therapy with a filtering procedure may be necessary.

A trabeculectomy with antifibrotic agents (mitomycin-C or 5-fluorouracil) or a glaucoma drainage device (aqueous shunt) have been found to be effective in controlling IOP in ICE syndrome patients.

However, maintaining long-term success can be challenging, as the fistula can be obstructed with advancing abnormal corneal endothelial cells.

Long-term surgical outcomes have been reported to be slightly better with glaucoma drainage implants (survival of 71% at 1 year, 71% at 3 years, and 53% at 5 years) versus trabeculectomy with antifibrotic agents (survival of 73% at 1 year, 44% at 3 years, and 29% at 5 years).

Regardless of the procedure, it has been noted that these patients typically require multiple surgeries to maintain stable IOP control.

If surgical success is not obtained with a trabeculectomy or glaucoma drainage device, it may be necessary to treat patients with a ciliary body destruction procedure. Typically this is done with diode laser cyclophotocoagulation (diode CPC), and is reserved for intractable cases of glaucoma.

Iridocorneal Endothelial Syndrome (ICE) is a group of conditions related to changes in corneal cells and the iris. The syndrome almost always involves cells moving from the cornea to the iris. Loss of cells from the cornea can cause corneal swelling, and the iris and pupil can become distorted.

When the corneal cells move, they can block fluid from draining properly through the eye’s microscopic drainage channels. This blockage causes pressure in the eye to build, leading to glaucoma.

Iridocorneal endothelial (ICE) syndrome is a rare and fascinating condition that can be challenging for ophthalmic surgeons to manage. It comprises a spectrum of three clinical entities: progressive essential iris atrophy, Cogan-Reese syndrome, and Chandler syndrome.

It is characterized by proliferative and structural abnormalities of the corneal endothelium, progressive obliteration of the iridocorneal angle, and iris anomalies such as atrophy and polycoria.

ICE syndrome is sporadic in presentation; it is usually unilateral and typically affects adult patients, females more often than males.

Glaucoma therapy, in the minimally invasive glaucoma revolution of the past several years, involves diligently treating the acute needs of each glaucoma patient with a keen eye on long-term planning for continued success.

This mindset becomes even more critical in younger patients, as well as those with secondary and refractory glaucoma. A road map to success for these patients will likely involve multiple strategies aimed at different targets of the glaucoma treatment pathway throughout their lives with the disease.

It is these subsets of glaucoma that may see the greatest benefit of new approaches to glaucoma treatment. The evolution of surgical glaucoma treatment options may allow for the longevity of vision and improved lifestyle that was once only imagined.

A Case Analysis - Understanding the Terrain

A 30-year-old female with the iridocorneal endothelial syndrome (ICE) who had been followed for several years with elevated intraocular pressure (IOP) recently presented to our glaucoma clinic.

She initially sought treatment 5 years ago with uncontrolled IOP in the high 30s and a Humphrey visual field with almost complete loss of the superior field and a 0.85 cup-to-disc ratio in the affected eye.

Her corrected visual acuity at that time was 20/30. Her anterior-segment changes consisted of an enlargement of her pupil with an irregular endothelial appearance of the cornea. Gonioscopic examination revealed broad areas of peripheral anterior synechiae.

After the failure of multiple drop therapy, she was treated surgically with a glaucoma implant. This initially lowered her IOP to the mid to high teens on 1 medication. Unfortunately, over several years, her IOP began to drift upward into the lower and mid-20s.      

There was a desire to avoid further surgical intervention due to her age and limited surgical options with her secondary glaucoma. Initial treatment involved adding multiple topical drops in an attempt to avoid the risks inherent with further surgery while lowering her risk of progression.

At the height of her drop therapy, she was taking 5 different classes of topical medication to manage her disease.

Mapping A Course

As medications were added, the inevitability of issues with the ocular surface and therapy compliance increased.

As irritation and redness became more of a problem, the IOP also began to rise back into the middle to high 20s with concern for progression on Humphrey visual field. A new interventional treatment was warranted.

It is at this point in the care of a patient that glaucoma specialists have to consider the current surgical map and path options for glaucoma. Even at the time of this patient’s initial filtration surgery with a shunt, her options were more linear.

Many glaucoma treatment plans would simply be a straight line from diagnosis to medication or laser followed by filtration.

Our current course map allows for varied paths of travel. If our past option was only to take the highway to filtration, our current options involve a variance of scenic routes to reach our end goals of vision preservation through pressure control and consideration of patient lifestyle and goals.

The main pathways fall into several categories, including treatment of trabecular or ciliary outflow, subconjunctival filtration through traditional or newer stenting procedures, and manipulation of aqueous flow through cyclodestruction.

Consider the patient when navigating a treatment path. In this case, due to the nature of the patient’s disease, which involved endothelial dysfunction and peripheral anterior synechiae within the angle, options for trabecular or ciliary outflow are eliminated.

As recently illustrated, subconjunctival filtration with Xen (Allergan)1 or the Ex-Press shunt (Alcon)2 might be an option for this patient, despite her previous tube shunt. These devices may decrease the opportunity for the proliferation of abnormal endothelial cells, which often cause the failure of trabeculectomy in this disease. 

However, in this case, there was a desire to avoid the use of antifibrotics in a young female with an active lifestyle. These devices may remain viable options if needed in the future. 

The decision was made to treat her glaucoma with micropulse transscleral diode laser cyclophotocoagulation.

The Iridex Cyclo G6 laser was set at a micropulse power setting of 2,000 mW. Slow, sweeping 10-second movements were used to treat each of the 4 quadrants of the eye for a total of 60 seconds per quadrant.

She was treated with a 3-week tapering dose of durezol starting at 3 times daily the first postoperative week. Her glaucoma medications were weaned over the first 6 weeks after the procedure based on IOP.

At her 6-month postoperative visit, her vision was 20/25 in the affected eye with an IOP of 8 mmHg on dorzolamide-timolol drops BID. She had also noted a decrease in ocular irritation and redness.

Micropulse transscleral diode laser cyclophotocoagulation is an effective treatment for refractory glaucoma and appears to have increased success in eyes with previous filtration surgery with relatively low complication rates.

The case of this patient suggests that this procedure is also a viable alternative in the treatment of ICE-associated glaucoma.