An excerpt from Dr. Frangie's book, Seeing is Believing, currently in the process of being published.

The accommodating style IOLs are actually able to flex in response to the ciliary muscle contracting – in a manner similar to how a natural lens would change shape in the younger eye. Very slight motion and flexing of the lens allows the eye to gain more “power” when a patient focuses from distant to near objects.(Figure 5 A & 5 B)

A video of Crystalens implantation may be viewed at www.frangieeye.com.

The other mechanism by which an intraocular lens may replace the loss of accommodation is through multifocal optics. The multifocal system has a modified optic (lens portion of the IOL) which is able to modify the light entering the eye and focus some light for near visualization and another portion focuses the energy to allow visualization of distant images. Simply speaking, the multifocal implants, apportions the light to different focal lengths so different distances are in focus; this occurs without effort from the patient and is a totally passive system. Thus, patients do not have to worry about looking through a certain portion of their implant to see at a specific distance.

In summary, advances in cataract surgery and its outcomes have gone hand-in-hand with the evolution of intraocular lenses. The latest quantum leap in IOL technology is the introduction of presbyopic intraocular lenses. Unlike standard monofocal IOLs, these lenses restore the eye’s ability to have a range of clear vision.

Vision Screening for Young Children

Children between the ages of 3 and 5 years should be seen at least once by an eye care professional to detect the presence of amblyopia or its risk factors, according to an updated statement issued by the U.S. Preventive Services Task Force (USPSTF).  The 2011 recommendation was made following an initiative undertaken by the USPSTF to update 2004 statement offering guidelines for vision screening in young children. 

The USPSTF reviewed multiple studies that evaluated the accuracy and outcomes of preschool vision screening tests.  They also assessed the effectiveness of early detection and treatment and the harm of screening treatment. 

The researchers found that vision screening tools used to assess preschool-age children accurately detected visual impairment, such as

• refractive errors
• strabismus
• amblyopia

The task force determined that early treatment for amblyopia in children 3 to 5 years of age, including the use of cycloplegic agents, patching and eyeglasses, leads to improved visual outcomes. 

The 2004 Guidelines also recommended vision screening for children between 3 and 5 years of age;  this review reconfirmed those recommendations based on updated evidence.  According to the statement, there is "adequate evidence that early treatment for amblyopia...for children 3 to 5 years of age leads to improved visual outcomes."

Annual Snapshot of Eye Injuries

In the United States, men are 3x more likely to suffer an eye injury, according to the Eye Injury Snapshot, and annual survey conducted by the American Academy of Ophthalmology (AAO) and the American Society of Ocular Trauma (ASOT).  Conducted during a 1-week period in the spring of 2010, the survey revealed that men suffered about three-quarters (73.5%) of all reported eye injuries, and the survey also found that most of the total eye injuries suffered occurred at home, while doing chores or playing sports. 

The AAO and the ASOT collected eye injury data each year to help increase public awareness and to encourage behavior that can help circumvent eye injuries.  The Eye Injury Snapshot survey also found the following:

• One quarter of eye injuries that occur at home resulted from play/sport activities
• One quarter occurred during home repair work or while using power tools.
• Most home-based eye injuries occurred in the yard or garden
• About 50% of reported injuries occurred in men and women 30-64 years of age; children < 12 years of age accounted for about 12% of injuries. 
• Almost half of eye injuries occurred between noon and 7:00 pm. 

To prevent some of the most common eye injuries that happen during household chores and repairs, the AAO and the ASOT recommend that every household have at least one pair of protective eyewear approved by the American National Standards Institute (ANSI).  ANSI-approved eye wear is available at most hardware and home improvement stores and can be identified by the mark "Z87".  For sports activities, eye wear approved by the American Society for Testing the Materials is recommended.  To locate Appropriate eyewear for specific sports, the AAO and the ASOT suggests that clinicians tell their patients to talk to their ophthalmologists or visit the AAO Web site, www.geteyesmart.org.

Statin Use and Cataracts Among Patients with Diabetes

Despite data linking prolonged statin use with cataract development,  a recent study shows that patients with diabetes who take statins for a long period of time have no greater risk of developing cataracts than patients who have not taken prolonged coursed of statins.  Conducted by Hermans et al from Cliniques Universitaires St. - Luc, Belgium (Diabetes Metab, 2011), the analysis studied 780 patients with type 2 diabetes (T2D) at very high risk for diabetic retinopathy (DR) and cataract, and determined that chronic statin therapy was neither cataractogenic nor was cataract presence associated with increased use of statin or other lipid-lowering drugs. 

According to the authors, studying patients with T2D offers "an ideal condition in which to assess the potential beneficial/detrimental effects of satins or other lipid-lowering drugs (LLD) on cataract, because T2D patients have a high prevalence of atherogenic dyslipidaemia as part of the associated metabolic syndrome, and also exhibit an increased incidence/prevalence of both hyperglycaemia and age-related cataracts(s)."

Major risk factors for cataract in T2D patients include hyperglycemia, diabetes duration and the presence of DR.  Additionally, the study noted that certain risk factors or markers may differ according to cataract subtype; for example, smoking is associated with nuclear opacities, ultraviolet radiation increase the risk for cortical opacities, and high blood pressure and corticosteroids raise the odds for subcapsular cataract. 

The diagnosis of cataract was made by an ophthalmologist in 16.8% of the study population during annual or biannual retinal checkups.  Lens extraction was considered a surrogate for cataract prevalence in patients who had undergone prior lens surgery for cataract.  Both age and duration of diabetes were significantly higher in the group with cataracts compared with those without.  DR was diagnosed in 23% of the patients.  According to the researchers, the "benefits of statin therapy in T2D may far outweigh any potential ocular drawbacks as a side effect which, in any case, were not supported by our findings."

Blood Pressure, Ocular Blood Flow, And Glaucoma

Despite an association between increased ocular perfusion pressure (OPP) and glaucoma, increasing blood pressure in an effort to modulate OPP appears to offer no value for treating glaucoma, according to a study published in a 2010 issue of the American Journal of Ophthalmology.  Caprioli and Coleman from the Jules Stein Eye Institute at the University of California, Los Angeles, conducted the study, which reviewed current literature and presented the findings of the Blood Flow in Glaucoma Discussion Group. 

"There is currently no evidence that manipulation of blood pressure or blood flow improves outcomes in glaucoma," the authors wrote.  "Although low OPP is now an established risk factor in glaucoma, is is not clear whether it is truly independent of the sum of 2 separate risk factor-high [intraocular pressure] and low blood pressure."

While in theory, controlling OPP via blood pressure may seem appealing, modulating OPP in practice is complicated by a range of factors, including the potential for inaccuracy in OPP measurements, the authors noted.  OPP measured during a routine examination may vary significantly from a patients physiologic OPP and therefore may not accurately correlate with the perfusion of the optic nerve head. 

The authors added that there is currently little evidence to identify which vascular beds are important in the development and prevention of glaucoma, and therapies not targeted to those beds could cause an unwarranted increase in overall pressure and an attendant increase in morbidity and mortality.  "There is the possibility that improving optic nerve perfusion by diverting blood from elsewhere (such as retinal capillary beds) may have unforeseen adverse effects, " they wrote. 

While future drugs developed to target specific pathways or receptors may offer hope for treatment of glaucoma via OPP modulation current evidence does not support such treatment.  "Glaucoma is a heterogeneous group of related diseases," the authors noted.  "There may be subgroups of patients in whom vascular factors are important, (but) those patients subgroups have not been well identified."

Decreasing the Risk of Vision Loss in Herpes Simplex Patients

The use of oral antiviral medications in patients with herpes simplex virus (HSV) appears to help decrease the risk of recurrence of epithelial keratitis, stromal keratitis, conjunctivitis, and blepharitis, and may decrease the risk of vision loss in these patients, according to a retrospective study conducted by Young et al from Mayo Clinic, Minnesota. The results of the study were published in a 2010 issue of the Archives of Ophthalmology.

In the study, researchers reviewed the outcomes of 394 residents of Olmsted County, Minnesota, diagnosed with ocular HSV from 1976 through 2007, and compared the frequency of recurrence and adverse outcomes such as vision loss or need for surgery, among patients treated prophylactically with oral antiviral medication and those who did not receive oral antiviral medication. According to their data, the authors found that patients who were not being treated prophylactically were
- 9.4 x more likely to have a recurrence of epithelial keratitis
- 8.4 x more likely to have a recurrence of stromal keratitis
- 34.5 x more likely to have a recurrence of blepharitis or conjunctivitis

Of the 20 patients included the study who experienced adverse outcomes, 17 were not being treated with oral antiviral medications immediately prior to the adverse event.

HSV is a common cause of corneal disease, and recurrence is relatively common. Following initial exposure and primary systemic infection, HSV establishes a latent infection in the trigeminal or other sensory ganglia, disease may recur in one or both eyes, with the risk of recurrence significantly increasing over time. The cumulative effect of these reactivations may lead to stromal inflammation or neurotrophic keratitis, resulting in scar of perforation, the authors noted.

"The results of this study suggest that oral antiviral prophylaxis should be considered for patients with frequent recurrences of corneal disease," the authors concluded. "Additionally, we recommend an evaluation of possible barriers preventing compliance with antiviral prophylaxis and a reassessment of the cost-effectiveness of long-term oral antiviral therapy."

10/3/11

Finding the Causes of Pediatric Cataracts

Although approximately 200,000 children worldwide are bilaterally blind from cataracts, the causes of the majority of cases remain undetermined, making prevention often problematic.  A retrospective study of pediatric cataracts by Lim et al from the Hospital for Sick Children, Canada, indicates that, although the cause remains unclear in many instances, understanding associated and potential contributing factors can be a powerful tool in both treatment and diagnosis of the condition. 

"Data on the characteristics of pediatric cataracts are useful for the purpose of diagnosis, genetic counseling, and selection of treatment options," the aauthors wrote in a 2010 issue of the American Journal of Ophthalmology.  "Prevention strategies also require information about etiology."

The authors reviewed 1122 eyes of 778 consecutive patients suffering from cataract.  About a third of syndrome-associated cataracts occurred in patients with Down syndrome.  Posterior subcapsular cataract was the most common morphologic type, and more than half of all patients presented with unilateral cataracts.  Almost 13% of patients examined had developed cataracts as the result of trauma, and almost 12% of cases had genetic origins.  Although the most common systemic association involved diseases treated with steroids, about 58% had no clear etiology. 

"Slightly over half of our patients had cataracts of unknown etiology despite examinations of their parents and siblings and, where indicated, laboratory investigations," the authors noted.  "Idiopathic cataract is a diagnosis of exclusion.  A metabolic and genetic examination tailored, with the assistance of a pediatrician, according to the medical and developmental history may be indicated when there are no other clear etiologic factors."  The authors added that while steroid use is clearly established a relationship between the incidence of cataracts and the dosage or duration of steroid therapy."