Histological Studies on Ageing Changes in the Cornea of Indian Buffaloes (Bubalus bubalis)

Abstract

Background: Affections of eye commonly encountered in all the species of animals. If these not treated in time, the vision may be hampered, this may impair the physical ability, utility and productivity of animals leading to economic loss to the animal owners. Corneal dystrophies like basement membrane dystrophy, stromal dystrophy, endothelial dystrophy, corneal erosions and corneal ulcerations etc., seen in the aged buffaloes. The current study was carried out to establish basic data and to provide authentic information to the clinicians on ageing changes in eyes of buffaloes.Methods: The study on age related changes in the cornea was conducted on 63 eye balls of locally available buffaloes of different breeds in and around Proddatur. These buffaloes were categorized into 3 groups based on their age i.e., group I (1-5 yrs), group II (6-10 yrs) and group III (11 yrs and above) buffaloes. The eyeballs were isolated and fixed with Davidson’s fluid. The paraffin sections of cornea were subjected for routine histological study.Result: The mean total thickness (µm) of cornea was increased from group I to III animals and it was 747.22±13.57, 853.33±11.05 and 897.22±8.06. Hence, The mean thickness (µm) of all five layers of cornea increased with advancement of age. Superficial corneal epithelial layer was made up of non keratinized stratified squamous epithelium with 6 to 7 layers at early age and 12-14 layers of cells in adult animals. The mean thickness (µm) of corneal epithelium in group I to III animals was 117.04±3.37, 122.59±2.23 and 133.71±3.55 respectively. Bowman’s membrane of cornea was measured 12.97±0.86, 17.22±0.55 and 18.71±0.68 in group I, II and III animals respectively. The mean thickness (µm) of corneal stroma in group I to III animals was 600.75±10.33, 672.22±10.46 and 690.00±5.32 respectively. This was mainly due to progressive increase in number of collagenous lamellae. The keratocytes became thin in old animals. Thickness of posterior band zone (PBZ) of Descemet’s membrane was increased with advancement of age. The mean thickness (µm) of Descemet’s membrane and endothelium together was in group I, II and III animals was 16.48±0.91, 41.29±2.25 and 54.82±1.44 respectively. The corneal endothelial cells were enlarged and increased in size in old buffaloes. The age related pigmentation was also noticed in epithelium and stroma of cornea in animals of group III. Density of sub basal nerve plexuses between the stroma and the corneal epithelium was not altered with advancement of age.