Researchers Find Genetic Link to Severe Form of Glaucoma

Angle-closure glaucoma (ACG) is a severe form of glaucoma in which intraocular pressure can build quickly and damage the optic nerve. Unlike the more common open-angle glaucoma, which progresses slowly, ACG can strike quickly and is a medical emergency; without prompt attention, rapid vision loss can occur.

Although ACG is treatable via various means, including laser surgery and eye medication, the foundation of the condition itself is still being studied and understood. Recently, researchers at the Jackson Laboratory—a nonprofit biomedical research institution—discovered a gene linked to the development of ACG.

Patients with ACG often have physical characteristics of the eyes that predispose their eyes to blockage of ocular fluid. When the fluid cannot drain properly, it can dramatically spike your intraocular pressure (IOP) and cause severe eye pain, nausea, headaches and blurred vision.

The Jackson Laboratory study revealed that the cause of IOP elevation was due to more than blockage by the iris. Researchers identified a strain of mouse with a genetic mutation that generates similar ocular features to those in ACG patients; these mice also develop high levels of IOP.

Researchers further found that the mutated gene could cause variations in axial length, including a dramatic reduction in axial length in people with hyperopia (farsightedness). In mice, this genetic mutation produces a protein that in turn breaks down other proteins within the eye. The research yielded the first connection between this protein and ACG.

The study may pave the way for future methods of early ACG detection, including identifying additional risk factors, and help reveal additional ways in which ACG can be treated.

To learn more about vision correction options and to find an ophthalmologist near you, please contact The LASIK Directory.

At-Home Glaucoma Tests: Do They Work?

Recently, there has been a great deal of media surrounding the possibility of at-home glaucoma tests. But, are they FDA-approved, do they actually work, and what can they actually tell you?

Although a number of websites proclaim that the online glaucoma test offered by Peristat Group is FDA approved, but in truth it is only FDA-cleared, which constitutes a much less rigorous evaluation of the technology, largely to assess whether the device is "substantially equivalent" to an already-existing technology. In this case, the pre-existing technology is a similar form of glaucoma test used in doctor's offices.

As far as whether it works or not, clinical research has shown that the test is about 90% accurate when compared to similar tests performed in doctor's offices. This is a pretty good level of accuracy considering it is a test you can take at home using just your computer and paying only $29.95 per evaluation (with a possible discount for signing up a for a year's worth of evaluations), much less than the cost of going to the doctor's office.

But what can an online glaucoma test actually tell you? The test works by having you focus on a white dot at the center of the screen while stimuli dots flash all around. These stimuli dots are at a certain contrast setting and appear in pre-set locations to test the status of your optic nerve. The results of the test are then reviewed by perimetry specialists and the results are emailed to you. You may be referred to a follow-up with your ophthalmologist.

The good news is that the test can actually identify damage to the optic nerve that is occurring as a result of glaucoma. Since glaucoma slowly erodes your vision from the periphery toward the center, you may not be aware of vision loss until your visual field is significantly restricted, while this test can tell you if your vision is being affected long before you become aware of vision loss.

Unfortunately, what this test cannot tell you is whether you are suffering some of the predecessor conditions to glaucoma, such as elevated intraocular pressure or related conditions. It cannot detect these conditions before optic nerve damage occurs, only tell you that the damage has occurred.

To prevent optic nerve damage from glaucoma, you need to schedule regular vision evaluations with your ophthalmologist. At-home glaucoma tests can serve as back-up or supplementary tests, but they cannot replace full glaucoma screenings in the office. Please contact us today to find a local ophthalmologist who can help protect your vision from loss due to glaucoma.

Anti-VEGF Agents and IOP Spikes

Anti-VEGF injection is being investigated for treatment of the vascular or wet form of age-related macular degeneration (AMD). This is not an FDA-approved use for these medications, but it is becoming a popular off-label use. Wet AMD has no other good treatments and can quickly lead to serious vision loss, so any treatment that can reverse vision loss and preserve these gains can be expected to increase in popularity. However, researchers have discovered one major roadblock to this treatment avenue.

Following injections of anti-VEGF medications, patients have been experiencing spikes in intra-ocular pressure (IOP). Increased IOP can lead to optic nerve damage, and is the primary characteristic of most forms of glaucoma. Over time, elevated IOP can lead to vision loss. Short-term IOP spikes are a common side effect of all forms of eye injections, but the IOP spikes seen in anti-VEGF treatments seems to be long-term. Research suggests is may be related to a clogging of the open angle. One possible explanation is that the anit-VEGF drugs (primarily Avastin (bevacizumab) and Lucentis (ranibizumab)) may have been mishandled prior to injection and therefore contain a large number of silicone oil droplets. At least one study has shown that freezing the anti-VEGF drugs can cause silicone oil to leach the vials into the drug itself. When this occurs it causes a significant increase in the number of particles in the drug. Once inside the eye, the natural flow of fluids will draw them into the open angle, clogging it and causing secondary glaucoma.

If you are over the age of 45 and notice any changes in your vision, it is important to talk to an eye doctor to learn whether AMD may be responsible, and whether treatments are available for your form of the disease. Contact us today to find a local ophthalmologist.

YAG Laser Treatment Does Not Prevent Pigmentary Glaucoma

Pigmentary glaucoma is an unusual form of the disease caused by blockage in the drainage canals. Unlike primary open angle glaucoma, in which years of normal sediment accumulates in the drainage canals, the debris clogging the angle is actually pigment granules from the iris. In some people, exercise, trauma, or other events cause the granules to flake off and become suspended in the aqueous humor. Once suspended, the eye's natural current takes them to the drainage angle, where they become caught and eventually prevent drainage. With drainage decreased, pressure builds up in the eye, leading to optic nerve damage and vision loss.

One proposed treatment for pigmentary glaucoma is ND:YAG laser peripheral iridotomy, a treatment for narrow angle glaucoma that actually blasts a hole in the iris to increase drainage. A study published in the journal ophthalmology, however, seems to cast doubt on the effectiveness of this treatment method. 116 patients with pigment dispersion syndrome and elevated intraocular pressure were assigned to either laser treatment or a control group to see if fewer developed pigmentary glaucoma with laser treatment than without. Unfortunately, the study showed that there was no difference between the time to development of pigmentary glaucoma in the two groups, nor did the laser group show a reduced incidence of pigmentary glaucoma.

Although ND:YAG laser peripheral iridotomy did not function as a good preventative treatment for pigmentary glaucoma, there are fortunately several other treatment options available. To learn more about pigmentary glaucoma and its treatment, contact a local ophthalmologist today.

Older Drivers and Their Eyesight

Study results regarding older drivers were recently published in Investigative Ophthalmology & Visual Science. The Salisbury Eye Evaluation and Driving Study (SEEDS) was conducted by scientists affiliated with Johns Hopkins University and looked at the vision, cognition and general health of licensed drivers aged 67 – 87.

There are over 30 million drivers in the U.S. aged 65 and over, which is also the fastest growing group of all licensed drivers in the country. As drivers age, their cognitive and visual function decreases impacting driving ability. The SEEDS research shows that a decrease in vision function is a key factor in an older driver's decision to restrict or discontinue driving. The most common conditions that bring about that decision include:

• Slow visual scanning
  
• Reaction time and attention
  
• Decreased ability to discern distances
  
• Contrast sensitivity loss (commonly associated with cataracts)
  

Each of these skills is necessary to help drivers to be aware of and appropriately respond to other vehicles, road conditions and road signs. Not associated with a decision to limit driving was a loss of visual field, commonly associated with glaucoma or age-related macular degeneration.

The study noted that women were four times more likely than men to stop or restrict their driving. Those who prefer to be driven were also four times more likely to self-limit driving than those who like to drive.

Self monitoring and regulation by aging drivers are essential ingredients in ensuring their safety and the safety of those with whom they share the road. The results of this study show that aging drivers are more apt to respond to some conditions than others, which might recommend increased education about the effect of visual field loss on the ability to drive.

Please contact the LASIK Directory today to find an experienced ophthalmologist in your area.

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