Comparative ocular anatomy of the western lowland gorilla.
OBJECTIVE
To examine the lowland gorilla (Gorilla gorilla gorilla) eye and determine similarities to and differences between the mountain gorilla (Gorilla gorilla beringei) and the human eye. In addition, we compare our findings of G. g. gorilla to previous reports on the eye of this subspecies.


METHODS
A 13-year-old deceased male lowland gorilla and a 34-year-old deceased female lowland gorilla were included in the study. Gross and microscopic examinations of the formalin-fixed right eyeball of each gorilla were carried out.


RESULTS
Globe dimensions of G. g. gorilla were similar to G. g. beringei and to humans. The limbal conjunctival epithelium and the choroid were densely pigmented. However, the distribution of the conjunctival pigment ring was different to that of G. g. beringei and the melanocytes of the choroid were unusually round. There were deep crypts in the anterior border layer of the iris, and the epithelium of the pars plana was uniquely irregular. Vertical corneal diameter was observed to be equal or greater than horizontal diameter in G. g. gorilla, which is in contrast to humans and to previous findings for G. g. beringei. Corneal thickness was closer to that of humans than to G. g. beringei. Posterior lens capsule thickness was noticeably greater than that of humans.


CONCLUSIONS
Although some variation between the ocular anatomy of G. g. gorilla and G. g. beringei does exist, the gross and microscopic findings closely resemble each other in these two subspecies. In addition, the eye of Gorilla appears remarkably similar to the human eye. However, comparison of measurements with those in humans is somewhat limited because formalin-fixation can introduce tissue shrinkage and artifact.
Knapp
Stefanie
S
Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA. stefanieknapp@comcast.net
McCulley
James P
JP
Alvarado
Thomas P
TP
Hogan
R Nick
RN
D000717:Anatomy, Comparative; D000818:Animals; D005123:Eye / Q000033:anatomy & histology*; D006071:Gorilla gorilla / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D013045:Species Specificity