Wednesday, January 18, 2006

DETAILED TECHNIQUES FOR EVALUATION OF SURGICAL AND AUTOPSY EYES


Detailed Techniques for Evaluation of Surgical and Autopsy Eyes

General
Autopsy eyes provide a unique experience for residents. Here you will be able to correlate clinical findings with direct visualization of lesions, and enhance understanding of dimensions, anatomical relationships and structural alterations. The following eyes / bottles should never be removed from the autopsy area:
-unlabeled bottles. Notify autopsy technical staff
-bottles containing more than one pair of eyes . Morgue staff should be notified
-bottles or eyes with a definitive or questionable diagnosis of unknown dementia
e.g. CJD
After at least 48 hours in fixative (10% formalin buffered with marble chips), the eyes are washed for 10 minutes twice in tap water and then placed in 50% ethanol. They will be stored in 50% ethanol thereafter. In a detailed study by a former JSEI resident Michele Lim, two days of equilibration was found to be necessary to re-expand the eyes; the eyes shrink in formalin.

Gross Work-up:
Preparation. Findings are recorded on a Gross Description Form, graphically and descriptively. Note: select the proper type of gross description sheet that reflects and the proper cut for the eye (standard with native lenses vs. coronal with pseudo- or aphakia). Always double check the pupil exam to confirm the proper form and cut for each eye. Simple examination reveals a white reflex if the native lens is in place; fixation results in precipitation of lens crystallins. A pseudophakic eye (plastic or silicone lens) and an aphakic eye (no lens) will appear clear the pupil will be dark. This is even more evident with proper transillumination. The eye is cleaned with forceps and blunt scissors. Beginning anteriorly, cut off the bulbar conjunctiva, leaving at least 3 mm in width on the globe if possible. Then, the rectus muscles are removed at their insertions. Episcleral tissue is stripped from anterior to posterior with thumb forceps and then severed. The superior and inferior oblique muscles are identified and removed leaving approximately 3 mm of tendon attached to the eye. The optic nerve is incised transversely with the razor blade in a coronal plane, leaving 2-3 mm attached to the eye. When removing the optic nerve, be sure to use a single continuous stroke in order that the transversely-cut surface will be smooth and interpretable. . The cut surface of the optic nerve will be examined later with oblique illumination. You should leave some episcleral tissue around the optic nerve at its entrance since the short posterior ciliary arteries enter here and may be important in the diagnosis of vascular disease.
External examination is done initially with the unaided eye and with a stereomicroscope when suspicious lesions are encountered. The eye should be reexamined to confirm the natural lens is present. Examination should proceed anatomically and include the conjunctiva, cornea, sclera, vortex veins, optic nerve, etc. Findings should be recorded on the gross sheet.
First you will need to determine which eye is the right and which is the left. This can be done by examining the muscular insertions. The globe is measured using the vernier calipers to the nearest one-tenth of a millimeter. Using the inferior oblique muscle as a handle, one can measure all three ocular diameters without changing grasp. Similarly, using the pointed ends of calipers, one can measure the optic nerve and the diameters of the cornea and pupil without re-grasping the handle. These measurements are recorded in the appropriate place on the gross sheet.
Transillumination

Transillumination is accomplished in our laboratory using the examination light fitted with an aluminum box to hold the eye. The box contains two round holes: one 34 mm in diameter to fit over the end of the Illuminator, and the other 20mm diameter (adult size) to hold the eye while transilluminating. Visualization is facilitated by extinguishing the room lights. Transillumination opacities can be marked with a tissue marking pen, a small amount of well placed ink etc.














0 Comments:

Post a Comment

Links to this post:

Create a Link

<< Home