What has your study of glaucoma in Asian Americans revealed thus far about the disease, and does it differ among subgroups in this population?

There is quite a spectrum of glaucoma presentation among various Asian groups. It has become well established that normaltension glaucoma (NTG) predominates among Japanese and Koreans. In a large clinic's population of Japanese Americans, my fellow investigators and I confirmed that NTG accounts for the vast majority of the glaucoma in this group.1 Angle-closure glaucoma (ACG) makes up a high proportion of the disease in Chinese, including Chinese in the United States.2 Our studies in clinical populations of Filipino Americans and Vietnamese Americans suggest that ACG constitutes a significant proportion of the glaucoma in these ethnic groups as well.3,4 Since both NTG and ACG are frequently difficult to diagnose, they require added vigilance on the part of clinicians.

Several of your studies have described the anatomic differences between Chinese and whites. Do your results explain why there is so much ACG among the former and practically none in the latter?

Together with collaborators in Beijing and Guangzhou, China, my group completed a large, prospective, crosssectional study of northern and southern mainland Chinese, Chinese Americans, and white Americans.5 All of the Chinese groups had statistically similar anterior segment parameters. When we compared those parameters against our findings for whites, however, almost all of them were smaller in the Chinese. For example, the anterior chamber volume and depth were smaller, and the angle was narrower in Chinese, even after adjustments for refractive error and axial length. Additionally, the iris was thicker in Chinese, and the dynamic behavior of the iris from dark to light conditions suggests that Chinese are anatomically and physiologically more prone to developing closed angles.

How does cataract surgery appear to lower IOP in ACG?

The main mechanism seems to be anatomic. In one of our studies, my fellow investigators and I found that wider opening of the angle after phacoemulsification was statistically correlated with a greater reduction in eye pressure.6 Additional studies by our group and others discovered that preoperative factors such as anterior chamber depth and lens vault help predict the amount by which IOP decreases after surgery.7 We currently have a project evaluating the trabecular meshwork's anatomy associated with cataract surgery, and the results are forthcoming.

Another theory related to the beneficial effects of phacoemulsification on IOP points to cytokine production by the trabecular meshwork cells as a possible mechanism for increased outflow after surgery.8Why do you invest so much time in mentoring students, residents, fellows, and visiting faculty?

As academicians, our greatest legacy is represented by the students whom we help educate and mentor. I have had the privilege of working with exceptional and motivated mentees from various levels—high school, college, medical school, residency, fellowship, and faculty— including ones from Asia, Europe, and South America. They stay connected, often in the form of continued collaboration, even after their research period with me has ended. In a way, my students teach me more through their youthful curiosity and questions. I take great pride in seeing them succeed in their careers and academia.

What do you enjoy most about life in San Francisco?

It has been wonderful living in the Bay Area. San Francisco offers the benefits of a large, international city with excellent restaurants, arts, and entertainment. At the same time, the city is small enough to feel cozy and safe, a place where you can comfortably raise your family. I am close to wine country to the north, ski resorts in Tahoe in the winter, and the high-tech industry to the south. From a professional viewpoint, many ophthalmic device and pharmaceutical companies are in close proximity such as Genentech, Carl Zeiss Meditec, Inc., and iScience Interventional. This has facilitated our collaboration and sharing of ideas.

  1. Pekmezci M, Vo BT, Lim A, et al. The characteristics of glaucoma in Japanese-Americans. Arch Ophthalmol. 2009;127(2):167-171.
  2. Seider MI, Pekmezci M, Han Y, et al. High prevalence of narrow angles among Chinese-American glaucoma and glaucoma suspect patients. J Glaucoma. 2009;18(8):578-581.
  3. Seider MI, Agadzi AK, Lee RY, et al. High prevalence of narrow angles among Filipino-American patients. J Glaucoma. 2011;20:139-142.
  4. Peng P, Nguyen H, Nguyen N, Lin S. Glaucoma and clinical characteristics in Vietnamese Americans. Curr Eye Res. 2011;36(8):733-738.
  5. Wang D, Qi M, He M, et al. Ethnic difference of the anterior chamber area and volume and its association with angle width. Invest Ophthalmol Vis Sci. 2012;31;53(6):3139-3144.
  6. Huang G, Gonzalez E, Peng P, et al. Anterior chamber depth, iridocorneal angle width and intraocular pressure changes after phacoemulsification: narrow versus open iridocorneal angles. Arch Ophthalmol. 2011;129(10):1283- 1290.
  7. Huang G, Gonzalez E, Lee R, et al. Association of biometric factors with anterior chamber angle widening and intraocular pressure reduction after uneventful phacoemulsification for cataract. J Cataract Refract Surg. 2012;38(1):108-116.
  8. Wang N, Chintala SK, Fini ME, Schuman JS. Ultrasound activates the TM ELAM-1/IL-1/NF-kappaB response: a potential mechanism for intraocular pressure reduction after phacoemulsification. Invest Ophthalmol Vis Sci. 2003;44(5):1977-1981.