The Meibomian glands being embedded in the tarsal plate, cysts in them present both on the conjunctival surface and towards the skin, but the contents are always evacuated from the former. =Instruments.= Walton’s iris knife, sharp spoon. =Operation.= Under adrenalin and cocaine. The eyelid is everted and a drop of the solution is injected into the cyst with a hypodermic syringe. A vertical stab is made into the cyst with the knife and the contents are then evacuated with a sharp spoon. Difficulty may arise in fixing the cyst whilst making the incision; this is best obviated by holding the everted lid between the finger and thumb. In some cases, when the cyst has persisted for a considerable time, the sac-wall becomes so thickened that it has to be dissected out before the mass in the lid will disappear. CHAPTER VI OPERATIONS UPON THE EXTRA-OCULAR MUSCLES SQUINT OPERATIONS =Indications.= Operations upon eyes with concomitant squint are undertaken for two purposes:-- (i) For cosmetic reasons, to remedy a deformity due to a squinting eye which is amblyopic. (ii) To rectify the muscular equilibrium in alternating or latent squints, so that binocular vision may be regained. When the operation is performed for the latter reason the adjustment will naturally have to be much more accurate than for the former, so as to bring about the superimposition of the images falling on each macula. The muscular balance is interfered with by the administration of a general anæsthetic, and therefore the results cannot be gauged accurately. Thus it is desirable that operations upon the ocular muscles should be performed under local anæsthesia. This is usually possible, except in the case of very small children. During and after the operation muscular equilibrium is tested by means of an electric light fixed to the ceiling immediately over the head of the patient (see Fig. 74). The room is darkened and the patient is made to look at the light. In a case with an amblyopic eye the reflection of the light should appear in the middle of each cornea if the eye be properly adjusted. In cases where good vision is present in both eyes the Maddox rod test should be used, the rod being placed before the eye not being operated on; the bar of light produced by the rod should pass through or within a few inches of the light if the adjustment has been performed accurately.