Ocular Growth & Myopia Research Laboratory
- Professor Neville McBrien
National & International Collaborators
- Dr Nancy Guzzo - Pernell - Peter MacCallum Institute, Melbourne
- Dr Gregor Wollensak - University of Dresden, Germany
The work of the ocular growth and myopia research laboratory is aimed at understanding the mechanisms that regulate ocular development and abnormal eye growth particularly with respect to the development of myopia. High degrees of axial myopia are associated with serious pathological changes such that myopia is a leading cause of blindness in developed countries. We apply a variety of approaches spanning the disciplines of optometry, biochemistry, molecular biology and pharmacology in order to understand and successfully treat pathological myopia.
Clinical Pathology in High Myopia
One of the major pathological complications in high myopia is chorio-retinal degeneration and retinal detachment. Early detection of myopia-induced retinal changes may allow initiation of treatment strategies, thus delaying the sight threatening pathology that accompanies high myopia. Using cohorts of high myopes we are clinically detailing the ocular changes and pathologies that occur in the myopic eye. In addition, ongoing collaborative studies are aimed at evaluating the clinical effectiveness of optical coherence tomography (OCT) in detecting retinal changes during myopia.
Neuropharmacological Control of Myopia
The use of the antimuscarinic drugs, such as atropine and pirenzepine, are successful at reducing myopia progression in young children. However, these drugs can have many unwanted side effects, and it is unclear how or where these drugs work in controlling myopia. We have identified the receptors in the eye to which these drugs are thought to bind and have investigated their levels during myopia development. Using molecular and receptor binding techniques, immunocytochemistry and specific pharmacological intervention strategies, ongoing studies are aimed at determining the mechanism of action of these drugs in preventing myopia.
Molecular Mechanisms of Scleral Change in Myopia
The primary structural cause of myopia is excessive ocular enlargement. As the outer coat of the eye, the sclera, regulates eye size, altered scleral biology is instrumental in allowing this enlargement to occur. Our laboratory is currently detailing the scleral alterations that occur during myopia and investigating which molecules may drive this process. Alterations in scleral biochemistry, DNA synthesis, proteoglycan and collagen production are assessed in our model system and using cell culturing techniques.
To advance our understanding of the regulation of ocular growth, we are investigating changes in ocular growth regulatory mechanisms at the molecular level. In particular we are examining changes in gene expression of growth factors implicated in the control of myopic eye growth (eg. bFGF and TGF?) using molecular (eg. RT-PCR, real-time PCR) and protein chemistry (ELISA, Western blot) techniques. Such studies will allow us to identify key molecules responsible for driving the scleral changes that result in myopia.
Visual Environment & Ocular Growth
Experimental evidence suggests that the retina is able to detect blur, assess whether the image is focussed in front or behind the retinal plane and alter ocular growth accordingly. We make use of this effect experimentally, using negative lenses to induce myopia and positive lenses to induce hyperopia. Studies in our model system are undertaken to better define this visually driven characteristic of eye growth. Results from these studies will provide an important insight into the role of the visual environment in human ocular growth and may possibly lead to clinically effective strategies to treat myopia.
Selected Recent Publications
- Metlapally, R, Jobling, AI, Gentle, A & McBrien NA. (2006). Characterization of the integrin receptor subunit profile in the mammalian sclera. Molecular Vision. 12:725-34.
- Jaworski, A, Gentle, A, Zele, AJ, Vingrys, AJ & McBrien NA. (2006). Altered visual sensitivity in axial high myopia: a local postreceptoral phenomenon? Investigative Ophthalmology & Visual Science. 47(8):3695-702.
- Yin GC, Gentle A & McBrien NA. (2004). Muscarinic antagonistic control of myopia: a molecular search for the MI receptor in chick. Molecular Vision. 10:787-93.
- Jobling AL, Nguyen MNH, Gentle A & McBrien NA. (2004). Isoform-specific changes in scleral transforming growth factor-ß expression and the regulation of collagen synthesis during myopia progression. Journal Biological Chemistry. 279(18):18121-18126.
- Phillips JR & McBrien NA. (2004). Pressure-induced changes in axial eye length of chick and tree shrew: significance of myofibroblasts in the sclera. Investigative Ophthalmology & Visual Science. 45(3):758-763.
- McBrien, NA and Gentle A. (2003). The role of the sclera in the development and pathological complications of myopia. Progress in Retinal and Eye Research 22, 307-338.
- Gentle, A, Liu, Y, Martin, JE, Conti, GL and McBrien, NA (2003). Collagen gene expression and the altered accumulation of scleral collagen during the development of high myopia. The Journal of Biological Chemistry 278, 16587-16594.