Study Validates Genetic Testing in Optimizing Treatment for the Most Prevalent Type of Glaucoma; Supports Need For InSite Vision's ISV-900 Glaucoma Genetic Test.

Business Editors & Health/Medical Writers

ALAMEDA, Calif.--(BW HealthWire)--Sept. 20, 2001

InSite Vision Incorporated (AMEX:ISV) announced today that a scientific study indicates that genetic testing for a prevalent variant of the TIGR/MYOC gene is one important element in optimizing the management and treatment of patients with the most common type of glaucoma, primary open-angle glaucoma (POAG).

The peer-reviewed manuscript, "Association of a single nucleotide polymorphism in the TIGR/MYOCILIN gene promoter with the severity of primary open-angle glaucoma," published in the September 2001 issue of the journal Clinical Genetics (volume 60:3, pages 220-225), was based on a retrospective study involving 142 patients with POAG. Research indicated that POAG patients who express the TIGR/MYOC gene variant known as MYOC.mt-1 were more likely to have more visual field damage, and less likely to respond to certain pharmacological treatments.

"This study further verifies the need for our ISV-900 glaucoma genetic test, which detects the presence of MYOC.mt-1 and several other TIGR/MYOC mutations, and can assist in determining the best therapeutic decision for these patients. The internationally recognized team of ophthalmic researchers who conducted this study drew the conclusion that given the high prevalence of glaucoma and the frequency of the MYOC.mt-l in the general population, MYOC.mt-l typing could be a matter of public health," stated S. Kumar Chandrasekaran, Ph.D., InSite Vision's CEO. "The timing of this publication is fortuitous. It further supports the use of the ISV-900 test for a specific portion of the population, at a time when final preparations for the U.S. commercial launch of ISV-900 are underway."

POAG is a highly prevalent optic neuropathy and a major cause of irreversible blindness. It is defined by cupping of the optic nerve head and alteration of the visual field. If not treated, it may cause insidious and irreversible damage to the optic nerve. Elevation of intraocular pressure (IOP) is a major risk factor that can predispose the onset and contributes to aggravation of POAG. This is important because lowering of IOP is currently the primary therapeutic strategy available for preventing degradation of the visual field of POAG patients.

Results of this study indicated individuals with POAG who harbor the MYOC.mt-1 variant are likely to show resistance to intraocular pressure lowering with traditional IOP-lowering agents such as beta-blockers and miotics. More aggressive treatment with newer therapeutic agents may be necessary to control IOP and to slow visual field loss.

"Overall, our results suggest that MYOC.mt-1 can be a useful indicator of poor IOP control and greater visual field damage in diagnosed POAG patients ... It would be useful to identify patients with the MYOC.mt-1 variant so that their therapy could be adjusted," according to the article's senior author Henri-Jean Garchon, M.D., Ph.D.

InSite Vision is an ophthalmic products company focused on glaucoma, ocular infections and retinal diseases. The Company's glaucoma activities include genomic research, using TIGR and other genes, for its diagnosis, prognosis and disease management test ISV-900, as well as ISV-205, the Company's novel glaucoma therapeutic. ISV-205 uses the Company's proprietary DuraSite(R) drug-delivery technology, which also is incorporated into the Company's ocular infection programs ISV-401 and ISV-403, and the Company's retinal program.

This news release contains, among other things, certain statements of a forward-looking nature relating to future events or the future business performance of InSite Vision. Such statements entail a number of risks and uncertainties, including but not limited to, market acceptance of the Company's products, including with respect to ISV-900. Reference is made to the discussion of risk factors detailed in InSite Vision's filings with the Securities and Exchange Commission, including its annual report on Form 10-K and its quarterly report on Form 10-Q for the quarter ended June 30, 2001. Any projections in this release are based on limited information currently available to InSite Vision, which is subject to change. Although any such projections and the factors influencing them will likely change, InSite Vision will not necessarily update the information since InSite Vision is only to provide guidance at certain points during the year. Actual events or results could differ materially and no reader of this news release should assume later that the information provided today is still valid. Such information speaks only as of the date of this release.

Note to Editors: InSite Vision Incorporated, InSite Vision and DuraSite are trademarks of InSite Vision Incorporated. Other trademarks that may be mentioned in this advisory are the intellectual property of their respective owners.