Involvement of Anoikis in Dissociated Optic Nerve Fiber Layer Appearance

Dissociated optic nerve fiber layer (DONFL) appearance is characterized by dimpling of the fundus when observed after vitrectomy with the internal limiting membrane (ILM) peeling in macular diseases. However, the cause of DONFL remains largely unknown. Optical coherence tomography (OCT) findings have indicated that the nerve fiber layer (NFL) and ganglion cells are likely to have been damaged in patients with DONFL appearance. Since DONFL appearance occurs at a certain postoperative period, it is unlikely to be retinal damage directly caused by ILM peeling because apoptosis occurs at a certain period after tissue damage and/or injury. However, it may be due to ILM peeling-induced apoptosis in the retinal tissue. Anoikis is a type of apoptosis that occurs in anchorage-dependent cells upon detachment of those cells from the surrounding extracellular matrix (i.e., the loss of cell anchorage). The anoikis-related proteins βA3/A1 crystallin and E-cadherin are reportedly expressed in retinal ganglion cells. Thus, we theorize that one possible cause of DONFL appearance is ILM peeling-induced anoikis in retinal ganglion cells.

Dissociated optic nerve fiber layer in a case of Terson syndrome

Purpose: To report a case of Terson syndrome who developed dissociated optic nerve fiber layer appearance after pars plana vitrectomy. Case report: The author reports a young male patient with Terson syndrome who developed bilateral vitreous hemorrhage and sub-internal limiting membrane hemorrhage after road traffic accident. He underwent pars plana vitrectomy and removal of the already detached internal limiting membrane and the sub-internal limiting membrane hemorrhage in both eyes. In both eyes, dissociated optic nerve fiber layer was appreciated and left eye had a peculiar resemblance to the appearance of cystoid macular edema. Conclusions: Dissociated optic nerve fiber layer appearance may be noted following vitrectomy and removal of detached internal limiting membrane in patients with vitreous hemorrhage and sub-internal limiting membrane bleed due to Terson syndrome.

Incidence and quantitative analysis of dissociated optic nerve fiber layer appearance: real loss of retinal nerve fiber layer?

Purpose: To assess the association between appearance of dissociated optic nerve fiber layer (DONFL) after internal limiting membrane (ILM) peeling and changes in the macular nerve fiber layer (NFL) area by spectral-domain optical coherence tomography (SD-OCT). Methods: This study included 132 consecutive patients who had successfully undergone vitrectomy with ILM peeling for idiopathic epiretinal membrane or macular holes and had been followed up for ≥6 months. Two examiners evaluated macular 5-line raster horizontal SD-OCT images and categorized the patients on the basis of presence (group I) or absence (group II) of DONFL. The average macular NFL areas in both groups were measured using ImageJ at baseline and 1, 3, and 6 months after surgery. Results: Among the 132 eyes of 132 patients, DONFL was noted in 42 (31.8%), 104 (78.8%), 106 (80.3%), and 106 (80.3%) eyes at 1, 3, and 6 months and at the last visit (12.8 ± 6.5 months) after surgery. These layers appeared most commonly between 1 and 3 months after ILM peeling. There was no significant difference in average macular NFL area between groups I and II (3453.4 ± 125.3 and 3513.0 ± 100.2 pixels, respectively) at 6 months after surgery (p = 0.56). Conclusions: Appearance of DONFL increased between postoperative months 1 and 3. Moreover, there was no significant difference in average NFL in terms of DONFL. Thus, appearance of DONFL might represent macular NFL rearrangement and reorganization rather than true mechanical damage to the NFL after ILM peeling.