Session Title: FP-16 Vitreoretinal Surgery IV
Session Date/Time: Sunday 14/09/2014 | 11:00-13:00
Paper Time: 12:04
Venue: Boulevard D
First Author: : D.Steel UK
Co Author(s): : K. White M. Habib
The appearance of a dissociated optic nerve fibre layer has been widely described after internal limiting membrane peeling. Its functional significance is unclear but paracentral scotomata and reduced retinal sensitivity have been associated with its occurrence. Its aetiology is uncertain but it has been hypothesised to relate to Muller end plate avulsion resulting from ILM peeling. Knowledge of the mechanism could potentially lead to strategies to reduce its occurrence. We aimed to assess whether the extent of cellular debris on the retinal side of peeled ILM was related to the extent of DONFL observed post-operatively.
Sunderland Eye Infirmary in North East England
The peeled ILM of a consecutive series of 30 patients undergoing macular hole surgery by two surgeons was collected and prepared for transmission electron microscopy (TEM). Ultrathin sections (70nm) were taken at 2 levels through the sample, stained with uranyl acetate and lead citrate and viewed on a Philips CM100 TEM. For estimation of the amount of cellular debris, images were taken at x7900 from 14 randomly sampled areas of the ILM. To quantify the amount of debris on each surface of the ILM a grid of lines (line length 2µm) was superimposed on each image. The number of intercepts between the grid line and retinal surface were counted. Another grid (line length 1µm) was then superimposed on each image and the number of intercepts between the grid lines and any retinal debris were counted. The percentage of retinal side surface covered by cellular debris was then calculated. Postoperatively the patients were examined at 3 months and high definition OCTs performed. The number and depth of inner retinal surface depressions characteristic of DONFL were recorded. This figure was then compared to the retinal debris findings on TEM.
There was a significant correlation between the extent of retinal surface debris and the extent of DONFL observed postoperatively. The most pronounced DONFL changes were seen in patients with larger fragments of cellular debris and in particular in those patients peeled with a diamond dusted scraper technique as compared to a pinch grip forceps technique.
The observation of the severity of DONFL being related to the extent and size of retinal cellular fragments on the ILM is consistent with the theory of DONFL being caused by Muller cell end plate trauma.