Quick Hits

Safer glaucoma surgery attracts investors

iStent designer Glaukos nets $112 million to fund corporate development.

By Jerry Helzner, Contributing Editor

Glaukos Corporation, designer and maker of the new procedural class iStent, raised net proceeds of $112 million to fund corporate development in a public stock offering earlier this summer.

The initial offering, priced at $18 a share, jumped to more than $30 a share in the first weeks of trading. Investors Business Daily noted that positive investor reaction to the Glaukos MIGS technology enabled the company to raise the offering price from an initial $13 to $15 range to $18 per share.

The iStent is used in micro-invasive glaucoma surgery (MIGS), a less invasive procedure that creates an outflow channel between the eye’s anterior chamber and Schlemm’s canal. The FDA approved the iStent in 2012 for use in combination with cataract surgery for patients with mild-to-moderate open-angle glaucoma.

A number of studies testing the iStent’s efficacy — and likely contributing to the IPO’s strong showing — were presented at conferences earlier this year.

Among these studies was one led by Reay Brown, MD, of Atlanta, and presented in San Diego at ASCRS.

This study of 54 eyes (37 patients) found that the iStent used in cataract surgery was effective in lowering IOP in 96% of patients with IOP greater than 18 mmHg, with the greatest reductions in patients with baseline IOP above 21 mmHg. This group of high-IOP patients averaged IOP reductions above 5 mmHg. The iStent procedure also helped drive a small reduction in the number of topical glaucoma medications required by the enrolled patients.

The iStent allows aqueous to flow directly into Schlemm’s canal, bypassing the trabecular meshwork.
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A 104-patient study led by Aaron Winter, MD, of Halifax, Nova Scotia, and presented at AGS, also in San Diego, found that a postoperative course of corticosteroids for inflammation following cataract surgery had no impact on affecting the performance of the iStent as an effective pressure-lowering therapy.

A 46-patient chart review presented by Morgan Renner, MD, of Rochester, NY, and also presented at AGS, found that implantation of one or more iStents during cataract surgery immediately prior to cataract extraction and IOL placement entails more advantages and fewer potential complications than implanting the iStent following the IOL insertion step in eyes with challenging conditions, such as small pupils or mature cataracts.

The study found that advantages of early implantation include optimal clarity of the angle and trabecular meshwork, optimization of anesthetics, unaltered ocular integrity for ease of iStent implantation and ability to implant the device prior to complications that can arise in complex cases.

And lastly, Shakeel Shareef, MD, of Rochester, NY, found in a review of 43 patients presented at AGS that obtaining goniophotographic evidence of proper iStent placement is critical in ensuring the optimal effectiveness of iStent performance.

The dry-eye plot thickens

Understanding the neuropathology is critical to treatment.

By René Luthe, Senior Editor

New research adds to the growing body of evidence that dry eye disease is a much more complicated disorder than first imagined: even pain is complex. Investigators note in a recent issue of Eye that some patients report transient pain while others complain of chronic pain.¹

After completing a retrospective literature review in PubMed, the investigators found evidence that chronic pain is more likely to be experienced by patients with an abnormality in their ocular sensory apparatus (i.e., neuropathic ocular pain) and with clinical evidence of dysfunction, including the presence of spontaneous dysesthesias, allodynia, hyperalgesia and corneal nerve morphologic and functional abnormalities. These dry eye patients are more resistant to topical therapy that is meant to optimize the ocular surface. The researchers theorized that evaluating for neuropathic ocular pain might affect the treatment of dry eye-associated chronic pain.

Currently, dry eye is divided into two categories, aqueous deficient and evaporative, with treatments directed toward improving these tear film components. Neurosensory dysfunction is not routinely tested or treated in the clinical setting, despite several studies indicating it can be a component of dry eye symptoms in some patients.

When ocular surface damage leads to the release of various inflammatory mediators, changes could occur in the central nervous system (CNS) and create central sensitization — defined as “pain hypersensitivity that may arise from reduced activation thresholds and abnormal signaling amplification within the CNS,” the investigators write. A telltale sign of central sensitization is pain that is “disconnected from the ongoing peripheral pathology” — something often seen in dry eye patients, when symptoms do not reflect ocular surface findings. And while central sensitization may be reversible initially, it often becomes permanent.

Though the presence of neuropathic pain is easiest to ascertain with questionnaires, the authors write, most dry eye questionnaires, including the Ocular Surface Disease Index and Dry Eye Questionnaire 5, don’t ask for that information. Further, the dearth of commercially available instruments able to assess ocular sensory apparatus function means that investigators have difficulty measuring features in dry eye.

The researchers say that data suggest patients with evidence of neuropathic pain and central sensitization likely also are the patients who continue to experience dry eye symptoms while undergoing therapies. Such patients, they postulate, may benefit from a multimodal approach, one that includes “treating ongoing ocular surface damage with ocular surface protection and anti-inflammatory agents, and ocular sensory apparatus dysfunction with antineuropathic pain treatment. … Differentiating between the different subgroups within dry eye and evaluating for the presence of neuropathic pain will be critical to individualizing the treatment of dry eye.” OM

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