THE OPHTHALMIC ARTERY: I. ORIGIN AND INTRA-CRANIAL AND INTRA-CANALICULAR COURSE

EXTENSIVE accounts of the blood vessels of the orbit are to be found in various text-books of ophthalmology and anatomy, but there are few systematic descriptions of the anomalies.The various authors differ very little from one another in their descriptions, and deal almost exclusively with the so- called normal pattern of the ophthalmic artery.It was therefore considered desirable to study the origin, course, branches, and anastomoses of the ophthalmic artery in detail. MaterialThe origin and intra-cranial and intra-canalicular course of the ophthalmic artery were studied in 106 human orbits obtained from 58 dissection-room cadavers.There were three specimens from male children aged 4, 11, and 12 years, and the rest were from adults mostly past middle-age.Both sides were examined in 48 individuals, and in the remaining ten only one.Some features were studied in 170 specimens (this includes the 106 mentioned above). MethodsThe skull was opened and the brain removed leaving behind a long stem of the internal carotid arteries.The optic tracts were cut so that the optic chiasma and optic nerves were left intact within the skull, and investigations were carried out by two methods:(i) In 56 specimens from 28 cadavers (22 adult males, 3 adult females, 3 children), the origin and intra-cranial and intra-canalicular course were studied under a low- power stereoscopic binocular dissection microscope with direct illumination from a ltmp having a high-power and low-voltage filament.Distances were measured by a micrometer disc introduced into the eye-piece of the microscope.(ii) The remaining fifty specimens (both sides in 20 individuals and only one side in 10) were examined with the naked eye.All the findings in those examined by the first method were submitted to statistical analysis and all the measurements and statistical data given in the text pertain to the first 56 specimens examined.The findings in the second group were not usually analysed statistically because they were not sufficiently detailed, but wherever the data from the second group are mentioned, a note to that effect is given in the text.