Ophthalmic Research – CAO Di




  • MSc, Ophthalmology and Visual Sciences, The Chinese University of Hong Kong
  • BS Med, Clinical Medicine, Harbin Medical University

Research Areas:

  1. Documentation of changes in anterior segment anatomy after lens extraction in primary angle closure glaucoma
  2. The pathophysiological mechanisms of pterygium development



  1. Ng TK, Yung JS, Choy KW, Cao D, Leung CK, Cheung HS, Pang CP. Transdifferentiation of periodontal ligament-derived stem cells into retinal ganglion-like cells and its microRNA signature. Sci Rep. 2015; 5:16429
  2. Ng TK, Huang L, Cao D, Yip YW, Tsang WM, Yam GH, Pang CP, Cheung HS. Cigarette smoking hiders human periodontal ligament-derived stem cell proliferation, migration and differentiation potentials. Sci Rep. 2015; 5:7828
  3. Rong SS, Peng Y, Liang YB, Cao D, Jhanji V. Does cigarette smoking alter the risk of pterygium? A systematic review and meta-analysis. Invest Ophthalmol Vis Sci. 2014, 55(10):6235-43.


Research Highlights:

(1) Documentation of anterior segment parameters before and after lens extraction in primary angle closure glaucoma

The anterior segment optical coherence tomography (AS-OCT) is a useful technique to image detailed structural layers of the anterior chamber in order to facilitate the detection of angle closure glaucoma. Cataract surgery with IOL implantation can increase the anterior chamber angle and can also cause deepening of the anterior chamber in glaucoma patients. We documented the anterior segments parameters by AS-OCT, including the anterior chamber depth (ACD), central corneal thickness (CCT), anterior chamber width (ACW), lens vault (LV), angle opening distances (AOD 500), trabecular iris angle (TIA), and pupil diameter (PD) in 0°, 180°, 45°, 225°, 90°, 270°, 135° and 315°.
Figure 1 and 2. Anterior segment OCT image of the right eye pre- and post-phacoemulsification and IOL implantation. The measurement of anterior chamber depth (ACD), anterior chamber width (ACW), central cornea thickness (CCT), lens vault and pupil diameter.


(2) Studying the pathophysiological mechanisms of pterygium development

Pterygium is defined as a triangular-shaped degenerative and hyperplastic process, occurring medially and laterally in the palpebral aperture, in which the bulbar conjunctiva encroaches onto the cornea. It is characterized by the corneal surface conjunctivalization, chronic fibrovascular lesion, extensive inflammation and connective tissue remodeling. The prevalence of pterygium in Chinese adults is about 11%. The standard treatment for pterygium is the surgical excision of abnormal tissue outgrowth followed by mitomycin-C or 5-fluorouracil soaking, or transplantation of a limbal conjunctival flap. We are investigating the pathophysiological mechanisms of pterygium development.
Figure 3. Pterygium belongs to a subgroup of conjunctival diseases as shown by the expression of conjunctival cell marker (CK13) on the pterygium tissue.