 he means by his saying and it became full thick and fat. and the like. this is because most of the layers of the eye are thicker than either of the two membranes that cover the optic nerve.
يريد بقوله وامتلأ وغلظ وسمن. وما أشبه ذلك. وذلك لأن طبقات العين أكثرها أغلظ من كل واحد من الغشاءين اللذين على العصب النوري.