The Optometrist Perspective by Harvey Yamamoto, OD

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Harvey Yamamoto, OD

For this month, I would like to write about Glaucoma. Many optometrists have become certified in treating Glaucoma. Current data tells us that we have over 2 million patients in the U.S. being treated for this disease.

Glaucoma accounts for over 10 million visits to their eye doctor each year. In terms of social security benefits, lost income tax revenues, and health care expenditures, the cost to the U.S. government is estimated to be over $1.5 billion annually. Glaucoma patients number more than 60 million patients worldwide and the Glaucoma market is currently estimated to be between $4.5 to $5 billion in the U.S., UE, and Japan alone.

Coming down the Pike: Man 01 Glaucoma Drug is the first new drug in the area in 20 years. This “First in Class Drub” treats intraocular Eye Pressure (IOP) with early tests indicating excellent results in normalizing IOP. This drug may also be effective in helping ease the symptoms associated with: Pediatric Glaucoma, AMD, & Cystic Kidney Disease. The pharmaceutical company that is working on this wonder drug is Q BioMed Inc. This innovative company has the jump on the competition with its focus on the ‘Schlemms’ Canal, which is responsible for 70-80% of fluid drainage in the eye. The Man 01 Glaucoma drug is the only drug to target the ‘Schlemms’ Canal.

Not all patients obtain their first prescription for eye drops, many do not regularly refill them, and some who have a bottle in hand do not use it with prescribed regularity. These problems are compounded by patients who run out of eye drops before their insurance plan allows them to obtain a refill and by the inability of others to safely hold a bottle half an inch over their eye and then successfully squeeze it to deliver medication to the cornea, sclera, or conjunctiva.

For all these reasons and more contribute to our patients poor adherence to drug therapy . Compliance can become a huge issue with our patients. As practitioners who have elected to treat these group of patients, we have to be cognizant of these issue’s. Studies are underway to replace the topical delivery system of eye drops. Punctal plugs, annular scleral rings, and contact lenses are under investigation as is intracameral delivery, a subconjunctival injection of IOP lowering drugs has been tested in the past, and preclinical studies are currently underway. Drug delivery systems lasting for 6 months seem to be within reach.

A third option is to abandon topical drug system altogether by using nonmedical means to lower IOP. Laser trabeculoplasty has been around for decades, has a great safety profile and definitely eliminates some of the issues of adherence. Unfortunately, trabeculoplasty often does not lower IOP enough to eliminate the need for eye drops, and even when it does, many of those patients will still eventually need to resume topical eye drop therapy.

ROI: Today’s practitioners are faced with the high cost of the available high tech equipment. i.e.: In our practice, we decided to upgrade our OCT and found ourselves staring at a $100,000 invoice. The unit which we replaced was purchased just 5 years ago. The newer unit had all the bells and whistles that we desired to have. Technology changes quickly these days. We also upgraded our 15 year old Visual Field machine. The older unit was performing perfectly but we wanted a faster unit. Our doctors are fully aware that the ROI is not a good investment. However, we all feel in our practice that the two instruments which we purchased works hand in hand with each other in helping to diagnose Glaucoma suspects and to periodically check their progression. We don’t want our patients under our care to lose vision. We have had 3 OCT units in our practice over the last 23 years. Each unit provides faster and more detailed information on the status of RNFL loss occurring in our patients.

Fundus camera: Having a good fundus camera is essential as this is where it all begins in our practice. We are on our 3 rd fundus camera during the past 23 years as well. Whenever one of our doctors suspects glaucoma then they can ask for a 3D picture for further evaluation. Our clinic is equipped with all the latest gadgets necessary to treat and monitor glaucoma patients.

Glaucoma may be divided into various subsets, and each patient is an individual. For these reasons, the treatment protocol for each patients varies from patient to patient.

Side Effects: For those practitioner who treat glaucoma, we have to be prepared for side effects associated with topical drug therapy. Maximal medical therapy refers to the most a patient can tolerate. Our patients who are on topical drug therapy have a choice of 5 categories of topical med’s from which to choose : beta blockers, carbonic anhydrase inhibitors, a-agonists, prostaglandin analogues and cholinergics. When I was in the military some 50 years ago, the only drugs that we had was epinephrine and pilocarpine.

Unfortunately most of med’s carry side effects-systemic. Neuropsychiatric and cardiovascular. One drop of timolol 0.5% significantly decreases pulse rate and exercise tolerance. Brimonidine can induce psychosis.

Carbonic anhydrase inhibitors can decrease libido, a side effect most likely attributable to malaise and depression.

I adivse my patients to use the techniques of eyelid closure and nasolacrimal duct obstruction when administering topical med’s to help reduce the systemic side effects of malaise and depression.

When prescribing topical B-blockers, it is important to consider patients other systemic med’s. The latter’s effects can be compounding in patients taking topical b-blockers with systemic b-blockers. Those taking antipsychotics can develop increased serum levels of the drugs when taking topical ophthalmic b-blockers.

Lifestyle: Patients wearing contact lenses may not wish to take topical med’s. For those patients, I will prescribe one daily dosing of PGA’s or B-blockers or both.

Other patients may not be able to instill the eye drops and for those patients, I refer them to our local OMD clinic fpr SLT filtering surgery.

DRY EYE: Most topical med’s contain a preservative known as BAK which is known to cause dry eye disease by causing inflammation and cellular damage. If one of my patients cannot tolerate topical med’s then they are referred out for some type of filtering surgery.

The tolerability of the topical med’s depends on the patient. Treatment must be tailored to his or her lifestyle, financial situation, combo-drugs and ability to tolerate side effects. Patients always have options and it is our job to educate them in order to help them make an informed decision on their medical care.

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