The Value represents Maximum Number of Warrants To Purchase Common Stock.

No definition available.

Name:	eyen_MaximumNumberOfWarrantsToPurchaseCommonStock
Namespace Prefix:	eyen_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The value represents number of shares.

+ References

No definition available.

+ Details

Name:	eyen_NumberOfShare
Namespace Prefix:	eyen_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The value represents number of units sold

+ References

No definition available.

+ Details

Name:	eyen_NumberOfUnitsSold
Namespace Prefix:	eyen_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The Period Purchase term of warrant, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	eyen_PurchaseTermOfWarrant
Namespace Prefix:	eyen_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of liability associated with funds outstanding loaned in the form of a security resale agreement between the entity and another party for the purchase and resale of identical or substantially the same securities at a date certain for a specified price.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226003-175313

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

+ Details

Name:	us-gaap_SecuritiesPurchasedUnderAgreementsToResellLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of vesting of award under share-based payment arrangement.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=eyen_DirectorsAndExecutiveOfficersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=eyen_ClassWarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=eyen_ClassBWarrantMember
Namespace Prefix:
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Subsequent Events (Details) $ / shares in Units, $ in Millions					1 Months Ended	12 Months Ended
	Mar. 24, 2020 USD ($) item $ / shares shares	Jan. 31, 2020 $ / shares shares	Aug. 16, 2019 shares	Jan. 14, 2019 $ / shares shares	Apr. 16, 2018 $ / shares shares	Dec. 31, 2019 $ / shares shares	Dec. 31, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross					175,668
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				3 years	36 months
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price \| $ / shares				$ 2.74	$ 8.72	$ 3.10	$ 6.39
Common Stock, Shares, Issued						17,100,726	11,468,996
Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			636,287	11,000			313,674
Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			45,285				60,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			24 months	24 months			36 months
Employees Consultants and Directors Under the 2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			681,572	11,000			395,999
Subsequent Event [Member]
Securities Purchased under Agreements to Resell, Liability \| $	$ 6.0
Proceeds from Debt, Net of Issuance Costs \| $	$ 5.3
Common Stock, Shares, Issued	2,675,293
Subsequent Event [Member] \| IPO [Member]
Number of Units Sold \| $ / shares	$ 2.21425
Subsequent Event [Member] \| Directors and Executive Officers [Member]
Number of Units Sold \| $ / shares	$ 2.42625
Subsequent Event [Member] \| Common Stock [Member]
Number of Share \| item	1
Subsequent Event [Member] \| Class A Warrant [Member]
Purchase Term of Warrant	1 year
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	0.5
Maximum Number of Warrants To Purchase Common Stock	1,337,659
Subsequent Event [Member] \| Class A Warrant [Member] \| IPO [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares	$ 2.058
Subsequent Event [Member] \| Class A Warrant [Member] \| Directors and Executive Officers [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares	$ 2.27
Subsequent Event [Member] \| Class B Warrant [Member]
Purchase Term of Warrant	5 years
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	0.75
Maximum Number of Warrants To Purchase Common Stock	2,006,495
Subsequent Event [Member] \| Class B Warrant [Member] \| IPO [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares	$ 2.4696
Subsequent Event [Member] \| Class B Warrant [Member] \| Directors and Executive Officers [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares	$ 2.724
Subsequent Event [Member] \| Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		0.33%
Subsequent Event [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		24 months
Subsequent Event [Member] \| Employees Consultants and Directors Under the 2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		25,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price \| $ / shares		$ 4.68