Organization	3 Months Ended
Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	1. Organization Graybug Vision, Inc., the Company or Graybug, is a clinical-stage biopharmaceutical company developing medicines for the treatment of diseases of the retina and optic nerve. The Company presently devotes substantially all of its resources to conducting research and development and raising capital. The Company was founded in May 2011 and maintains facilities in Redwood City, California and Baltimore, Maryland. The Company is subject to risks common to clinical stage companies in the biopharmaceutical industry, including dependence on the clinical success of its product candidates, ability to obtain regulatory approvals of its product candidates, compliance with regulatory requirements, the need for substantial additional financing and protection of its proprietary technology. Initial Public Offering On September 29, 2020, the Company completed its initial public offering, or IPO, and issued and sold an aggregate of 6,468,750 shares of common stock (inclusive of 843,750 shares issued and sold pursuant to the exercise of the underwriters’ option to purchase additional shares on October 22, 2020) at a price of $16.00 per share for net proceeds of $92.0 million, after deducting underwriting discounts, commissions and offering expenses. Prior to the completion of the IPO, all 117,809,883 shares of convertible preferred stock then outstanding were converted into 13,085,913 shares of common stock. Reverse Stock Split On September 18, 2020, the Company effected a 9.0058:1 reverse stock split of its issued and outstanding common stock. Upon the effectiveness of the reverse stock split, (i) all shares of outstanding common stock were adjusted; (ii) the conversion prices of the convertible preferred stock were adjusted; (iii) the number of shares of common stock for which each outstanding option and warrant to purchase common stock is exercisable were adjusted; and (iv) the exercise price of each outstanding option and warrant to purchase common stock was adjusted. All of the outstanding common stock share numbers (including shares of common stock subject to the Company’s options, warrants and as-converted for the outstanding convertible preferred stock), share prices, exercise prices and per share amounts contained in the condensed financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented. The par value per share and the authorized number of shares of common stock were not adjusted as a result of the reverse stock split. Going Concern Considerations The Company incurred losses from operations and had negative cash flows from operating activities for the three months ended March 31, 2021, and the Company’s accumulated deficit at March 31, 2021 was $144.8 million. The Company’s current operating plan indicates it will continue to incur losses from operations and generate negative cash flows from operating activities, given ongoing expenditures related to extensive research and development and the Company’s lack of revenue-generating activities at this point in the Company’s life cycle. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. Based upon the Company’s current operating plan, the Company believes its existing cash, cash equivalents and short-term investments will enable the Company to fund its operating expenses and capital expenditure requirements in excess of 12 months from the issuance date of these financial statements. The Company bases this estimate on assumptions that may prove to be wrong, and it could utilize the available capital resources sooner than it currently expects. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations and ultimately achieve profitable operations. The Company bases the sufficiency of its existing cash, cash equivalents and short-term investments to fund its operations on the current period re-forecast of the Company’s projected cash burn rate following the Company’s decision to pause its Phase 3 clinical trial for GB-102. In March 2021, the Company determined not to proceed with the significant investment required to initiate two Phase 3 clinical trials for GB-102 in late 2021. As a result, management now believes that the Company’s current cash, cash equivalents and short-term investments are adequate to meet its needs for the next 12 months from issuance, and the Company will seek to raise additional funds in order to further advance its research and development programs, operate its business and meet its obligations as they come due. The Company is pursuing financing alternatives, similar to what the Company has previously executed, which include equity financing. Such sources of capital may not, however, be available to the Company in the necessary time frame, in the amounts that the Company requires, on terms that are acceptable to the Company, or at all. If the Company is unable to raise the necessary funds when needed or reduce spending on currently planned activities, it may not be able to continue the development of its products or the Company could be required to delay, scale back, or eliminate some or all of its research and development programs and other operations and will materially harm its business, financial position and results of operations. COVID-19 Pandemic The impact of the worldwide spread of a novel strain of coronavirus (“COVID-19”) has been unprecedented and unpredictable, but based on the Company’s current assessment, the Company does not expect any material impact on its long-term strategic plans, operations and its liquidity due to the worldwide spread of COVID-19. However, the Company is continuing to assess the effect on its operations by monitoring the spread of COVID-19 and the actions implemented to combat the virus throughout the world and its assessment of the impact of COVID-19 may change.

Organization

3 Months Ended

Mar. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1. Organization

Graybug Vision, Inc., the Company or Graybug, is a clinical-stage biopharmaceutical company developing medicines for the treatment of diseases of the retina and optic nerve. The Company presently devotes substantially all of its resources to conducting research and development and raising capital. The Company was founded in May 2011 and maintains facilities in Redwood City, California and Baltimore, Maryland.

The Company is subject to risks common to clinical stage companies in the biopharmaceutical industry, including dependence on the clinical success of its product candidates, ability to obtain regulatory approvals of its product candidates, compliance with regulatory requirements, the need for substantial additional financing and protection of its proprietary technology.

Initial Public Offering

On September 29, 2020, the Company completed its initial public offering, or IPO, and issued and sold an aggregate of 6,468,750 shares of common stock (inclusive of 843,750 shares issued and sold pursuant to the exercise of the underwriters’ option to purchase additional shares on October 22, 2020) at a price of $16.00 per share for net proceeds of $92.0 million, after deducting underwriting discounts, commissions and offering expenses. Prior to the completion of the IPO, all 117,809,883 shares of convertible preferred stock then outstanding were converted into 13,085,913 shares of common stock.

Reverse Stock Split

On September 18, 2020, the Company effected a 9.0058:1 reverse stock split of its issued and outstanding common stock. Upon the effectiveness of the reverse stock split, (i) all shares of outstanding common stock were adjusted; (ii) the conversion prices of the convertible preferred stock were adjusted; (iii) the number of shares of common stock for which each outstanding option and warrant to purchase common stock is exercisable were adjusted; and (iv) the exercise price of each outstanding option and warrant to purchase common stock was adjusted. All of the outstanding common stock share numbers (including shares of common stock subject to the Company’s options, warrants and as-converted for the outstanding convertible preferred stock), share prices, exercise prices and per share amounts contained in the condensed financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented. The par value per share and the authorized number of shares of common stock were not adjusted as a result of the reverse stock split.

Going Concern Considerations

The Company incurred losses from operations and had negative cash flows from operating activities for the three months ended March 31, 2021, and the Company’s accumulated deficit at March 31, 2021 was $144.8 million. The Company’s current operating plan indicates it will continue to incur losses from operations and generate negative cash flows from operating activities, given ongoing expenditures related to extensive research and development and the Company’s lack of revenue-generating activities at this point in the Company’s life cycle. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

Based upon the Company’s current operating plan, the Company believes its existing cash, cash equivalents and short-term investments will enable the Company to fund its operating expenses and capital expenditure requirements in excess of 12 months from the issuance date of these financial statements. The Company bases this estimate on assumptions that may prove to be wrong, and it could utilize the available capital resources sooner than it currently expects. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations and ultimately achieve profitable operations. The Company bases the sufficiency of its existing cash, cash equivalents and short-term investments to fund its operations on the current period re-forecast of the Company’s projected cash burn rate following the Company’s decision to pause its Phase 3 clinical trial for GB-102.

In March 2021, the Company determined not to proceed with the significant investment required to initiate two Phase 3 clinical trials for GB-102 in late 2021. As a result, management now believes that the Company’s current cash, cash equivalents and short-term investments are adequate to meet its needs for the next 12 months from issuance, and the Company will seek to raise additional funds in order to further advance its research and development programs, operate its business and meet its obligations as they come due. The Company is pursuing financing alternatives, similar to what the Company has previously executed, which include equity financing. Such sources of capital may not, however, be available to the Company in the necessary time frame, in the amounts that the Company requires, on terms that are acceptable to the Company, or at all. If the Company is unable to raise the necessary funds when needed or reduce spending on currently planned activities, it may not be able to continue the development of its products or the Company could be required to delay, scale back, or eliminate some or all of its research and development programs and other operations and will materially harm its business, financial position and results of operations.

COVID-19 Pandemic

The impact of the worldwide spread of a novel strain of coronavirus (“COVID-19”) has been unprecedented and unpredictable, but based on the Company’s current assessment, the Company does not expect any material impact on its long-term strategic plans, operations and its liquidity due to the worldwide spread of COVID-19. However, the Company is continuing to assess the effect on its operations by monitoring the spread of COVID-19 and the actions implemented to combat the virus throughout the world and its assessment of the impact of COVID-19 may change.