Definition of Macular and Extramacular Tractional Retinal Detachment
The provided evidence does not contain specific definitions for macular versus extramacular tractional retinal detachment (TRD) based on disc diameter measurements.
Available Terminology from Guidelines
The American Academy of Ophthalmology's 2020 Preferred Practice Pattern defines subclinical retinal detachment (in the context of rhegmatogenous detachment) as extending more than 1 disc diameter from the posterior edge of the retinal break, less than 2 disc diameters from the equator, and not impairing the field of vision 1. However, this definition applies to rhegmatogenous detachments, not tractional detachments.
Clinical Context for Tractional Retinal Detachment
Tractional retinal detachments occur when contractile forces in the vitreous and neovascular tissue lead to detachment of the neurosensory retina, most commonly in proliferative diabetic retinopathy 2, 3.
Functional Classification Used in Practice
While formal disc diameter-based definitions are not established in the provided guidelines, the literature distinguishes TRDs based on macular involvement:
Extramacular TRD: Detachment that does not involve the center of the macula and can remain stable for extended periods under observation 4
Macula-threatening TRD: Detachment approaching but not yet involving the macula, which may cause macular edema and reduced vision even without direct macular detachment 4
Macular TRD: Detachment involving the macula, which requires surgical intervention 5, 4
Clinical Decision-Making
Vitrectomy surgery is indicated for recent (<6 months duration) TRD involving the macula, progressive TRD that threatens the macula, and chronic macula-involving TRDs (>6 months duration) 5.
Extramacular tractional detachment can be observed as long as the center of the macula is not threatened 4.
Important Caveat
The distinction between macular and extramacular TRD in clinical practice is based on anatomic involvement of the foveal center rather than specific disc diameter measurements, unlike the disc diameter criteria used for subclinical rhegmatogenous detachments 4.