Stock Incentive Plans - Narrative (Details)	3 Months Ended
Mar. 28, 2020 installment shares
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equal vesting installments \| installment	3
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equal vesting installments \| installment	3
2017 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (shares)	158,206
2017 Omnibus Incentive Plan \| PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (shares)	124,863
2017 Omnibus Incentive Plan \| RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (shares)	155,550

Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Equal Vesting Installments

No definition available.

Name:	eye_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfEqualVestingInstallments
Namespace Prefix:	eye_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ 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 (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=eye_RestrictedStockUnitsRSUsServiceBasedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=eye_TwoThousandSeventeenOmnibusIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=eye_RestrictedStockUnitsPSUsPerformanceBasedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: