Can the Macula be Attached if View Is Obscured by a Bullous Retinal Detachment? A Mathematical Consideration

The purpose of this study was to determine if it is possible for the macula to remain attached if a bullous retinal detachment blocks the examiner's view to the macula.

A mathematical analysis compared the arc length of the attached retina versus the length of a detached retina necessary to obscure the macula (hang over the visual axis). The shape (oblate ellipsoid) and dimensions of the retina were based on a published study. The complete path of the hanging retina was calculated as a static catenary so as to depict the lowest possible position ("worst case scenario").

The measured and calculated angle between the fovea and ora serrata was 105 degrees. When considering a catenary shape of the hanging retina, the macula could, mathematically, still be attached despite the retina hanging down 1.03 mm below the visual axis for an emmetropic eye. The maximal distance calculated was 1.095 mm for a -12 diopter (D) myopic eye.

If the macular center cannot be viewed due to a bullous superior retinal detachment hanging into the examiner's view, it is unlikely but possible that the macula remains attached. If the view is obscured by at least 1 mm below the fovea, it is not mathematically possible for the fovea to be attached.

The status of the macula being detached is subject to mathematical constraints, which, explored herein, offer a higher certainty of clinical decision making that could inform management for better clinical results.