Abstract
Abstract: :
Purpose: To study the transition zone between coloboma of choroid and normal retina using ocular coherence tomography (OCT) Methods: Prospective study of 25 eyes of 17 patients. OCT was done to evaluate the transition zone between coloboma and normal retina. Results: While 22 eyes had coloboma with attached retina and came for routine examination, 2 eyes had clinical retinal detachment and 1 eye had successful reattachment after vitreo retinal surgery. The following findings were seen. 1) Transition from normal neuro sensory retina to inter calary membrane can be abrupt or gradual. 2) Transition is indicated by progressive thinning. 3) Outer retinal layers are initially lost while inner retinal layers are identifiable further into the coloboma. 4) In cases with retinal detachment, communication between subretinal and sub intercalary membrane space can be demonstrated. 5) Such communications are focal, and not all along the coloboma margin, indicating relatively strong normal adhesion between retinal pigment epithelium and outer retinal layers at margin of coloboma .6) Contrary to belief, splitting of retinal layers near the margin of coloboma and merger of outer layers with RPE was not observed. 7) Cystoid spaces resembling schisis cavities are seen both in retina and ICM in eyes with retinal detachment (in inner and outer layers). 8) Shallow retinal detachments not clinically seen are evident on OCT between disc and coloboma in eyes where disc is close to the coloboma. 9) The retina in this isthmus area also has altered architecture. 10) Retina may be thickened near the margin creating a hump and this thickening is restricted to the inner layers Conclusions: Inner retinal layers are more resistant to colobomatous process than outer layers. Communication between sub retinal and sub intercalary membrane space can be demonstrated by OCT.
Keywords: retinal detachment • imaging/image analysis: clinical