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Prevention of visual field defects after macular hole surgery
1Department of Ophthalmology, Cork University Hospital, National University of Ireland Cork, Wilton, Cork, Republic of Ireland.
Background/Aim:
The pathogenesis of visual field loss associated with macular hole surgery is uncertain but a number of explanations have been proposed, the most convincing of which is the effect of peeling of the posterior hyaloid, causing either direct damage to the nerve fibre layer or to its blood supply at the optic nerve head. The purpose of this preliminary prospective study was to determine the incidence of visual field defects following macular hole surgery in cases in which peeling of the posterior hyaloid was confined only to the area of the macula.
Methods:
102 consecutive eyes that had macular hole surgery had preoperative and postoperative visual field examination using a Humphrey's perimeter. A comparison was made between two groups: I, those treated with vitrectomy with complete posterior cortical vitreous peeling; and II, those treated with a vitrectomy with peeling of the posterior hyaloid in the area of the macula but without attempting a complete posterior vitreous detachment. Specifically, no attempt was made to separate the posterior hyaloid from the optic nerve head. Eyes with stage II or III macular holes were operated. Autologous platelet concentrate and non-expansile gas tamponade was used. Patients were postured prone for 1 week.
Results:
In group I, 22% of patients were found to have visual field defects. In group II, it was possible to separate the posterior hyaloid from the macula without stripping it from the optic nerve head and in these eyes no pattern of postoperative visual field loss emerged. There were no significant vision threatening complications in this group. The difference in the incidence of visual field loss between group I and group II was significant (p=0.02). The anatomical and visual success rates were comparable between both groups.
Conclusion:
The results from this preliminary study suggest that the complication of visual field loss after macular surgery may be reduced if peeling of the posterior hyaloid is confined to the area of the macula so that the hyaloid remains attached at the optic nerve head. The postoperative clinical course does not appear to differ from eyes in which a complete posterior vitreous detachment has been effected during surgery.