IOP management for vision preservation

November 10, 2008

Management of IOP is the mainstay of glaucoma therapy. Misleading and incorrect information, however, can interfere with appropriate patient management. Helping clinicians separate fact from fiction, speakers at a symposium provided updates on key aspects of IOP and glaucoma management for long-term control of disease and promotion of vision preservation.

Management of IOP is the mainstay of glaucoma therapy. Misleadingand incorrect information, however, can interfere withappropriate patient management. Helping clinicians separate factfrom fiction, speakers at a symposium provided updates on keyaspects of IOP and glaucoma management for long-term control ofdisease and promotion of vision preservation.

Program chairman and moderator Dale K. Heuer, MD, launched theevening session with tips on identifying and evaluating patientsat risk. He led the audience through four key topics. First, heexplained that central corneal thickness is only one factorinfluencing the accuracy of Goldmann tonometer measurements, thusIOP should only be qualitatively corrected. He also observed thatIOP measurements taken in the office frequently underestimatepeak circadian IOP and suggested that supine IOP measurementsestimate peak nocturnal IOP better than sittingmeasurements.

Dr. Heuer also discussed the role of optic disc hemorrhage (ODH)in glaucoma development or progression. While they are notpathognomic, they are associated with increased risk ofdevelopment or progression of glaucoma, he said. If a patient hasODH but IOP control is good, the appropriate patient managementapproach is to discuss adherence, while if IOP control ismarginal, the clinician should consider starting or intensifyingtherapy. Increased frequency of surveillance, including morefrequent office visits, visual fields, and disc examinationand/or imaging, also is advised.

Regarding the influence of family history and ethnicity, Dr.Heuer noted that they are both risk factors for glaucoma. Thefirst-degree relatives of glaucoma patients are at particularlyhigh risk and should be advised to undergo period evaluation.Also, studies show that African-Americans and Latinos are atgreater risk of developing glaucoma than Caucasians.

Dr. Heuer is professor and chairman, Department of Ophthalmology,Medical College of Wisconsin, and director, Froedtert Hospitaland Medical College of Wisconsin Eye Institute, Milwaukee.

Preferred practice patterns for POAG state that clinicians shouldset a target pressure goal and treat to it, said Robert M.Feldman, MD. Not treating to a target pressure has been shown inclinical trials to result in high rates of progression.

Guidelines for target pressure suggested by clinical trials orpractice guidelines should be adjusted for the individual patientand modified if the patient’s medical history changes, continuedDr. Feldman. He is clinical professor and deputy chairman of theDepartment of Ophthalmology and Visual Science, University ofTexas Medical School at Houston, and director of the glaucomaservice at the Cizik Eye Clinic in Houston.

If progressive disc or visual field changes are observed, adjustthe target IOP downward, whereas if the optic nerve status hasbeen stable and IOP has been low for 5 or more years, the targetcan be adjusted upward, and medication use may be adjusted aswell.

The management plan should be changed if the patient reaches thetarget IOP but optic nerve damage continues, or if the patient isnoncompliant, cannot tolerate the prescribed medication, ordevelops contraindications to the medication.

Medications are typically the first-line therapy. The clinicianshould choose an agent likely to achieve a 30% decrease in IOP,preferably one with the fewest clinically or cosmeticallyimportant side effects. If adjunctive therapy is necessary, addan agent that works well with the first-line medication over theentire 24-hour period, Dr. Feldman advised. He cautioned againstmoving directly to a fixed combination agent as the second-linechoice, as it may unnecessarily cause side effects.

Managing the safety and tolerability of glaucoma therapy over thelong-term is a constant challenge, said Marguerite McDonald, MD,FACS, clinical professor of ophthalmology, New York UniversitySchool of Medicine, New York, and adjunct clinical professor ofophthalmology, Tulane University Health Sciences Center, NewOrleans, Louisiana. Both glaucoma and dry eye are conditions thatpredominantly affect the elderly, and they are often found in thesame patient. Effectively managing these comorbidities adds tothe complexity of treatment.

Dry eye, a multifactorial disease, can occur for reasonsunrelated to glaucoma, but alternatively, glaucoma therapy couldbe implicated in the development of symptoms such as burning andpain. The preservative benzalkonium chloride (BAK) has beenassociated with ocular surface disruption, the flip side of itsbeneficial role as an antimicrobial agent found in nearly threefourths of prescription and over-the-counter eye drops, Dr.McDonald said. Studies have shown that BAK has a negative impacton the ocular surface and cellular physiology and reduces tearfilm breakup time. Corneal surface damage can occur with aslittle as one month of use of a BAK-preserved agent.

Pharmaceutical companies have begun to market BAK-freeformulations of certain glaucoma medications. Other options inthe future could include unit dose preservative-free glaucomadrops and multidose preservative-free delivery devices.Presently, these options would be prohibitively expensive andhave other drawbacks, Dr. McDonald said.

If a patient has concomitant glaucoma and ocular surface disease,the best management approach is to treat any signs or symptoms ofOSD very aggressively, she added. Also, clinicians use the reportrecently issued by the Dry Eye Workshop to guide diagnosis andtherapy.

Ocular irritation complaints expressed by a glaucoma patient arenot necessarily due to dry eye, however, according to JasonBacharach, MD, associate professor of ophthalmology and co-chair,Glaucoma Division, California Pacific Medical Center, SanFrancisco. Regular testing during routine exams can helpdetermine the nature of the problem and lead to more effectivetreatment, Dr. Bacharach added.

Tear breakup time, lissamine green, and Schirmer testing can allbe performed routinely, although the Schirmer test often producesfalse positives or negatives if incorrectly carried out.Medication has long been considered the first-line approach toglaucoma therapy, Dr. Bacharach said, but recent studies havesuggested that selective laser trabeculoplasty is similarlyeffective, and the two therapies are complementary.

Dr. Bacharach also predicted that surgical alternatives totrabeculectomy that are currently being explored may benefitglaucoma patients in the near future.

The dinner symposium was held at the Fernbank Museum of NaturalHistory during the American Academy of Ophthalmology annualmeeting in Atlanta.

This continuing medical education activity was jointly sponsoredby the New York Eye and Ear Infirmary and cme² inpartnership with Ophthalmology Times, and was supportedthrough an unrestricted educational grant from PfizerOphthalmics.