Morphological Characteristics and Intercellular Connections of Corneal Keratocytes

PURPOSE: To investigate the morphological characteristics of keratocytes and the interconnection of keratocytes with adjacent keratocytes using the flat preparation method and scanning electron microscopy with a frontal section of the human corneal stroma. METHODS: The thin, corneal collagen lamellae were carefully dissected from the cornea (n=7), which had been stained by the flat preparation method. The remaining tissue was fixed in 3% glutaraldehyde and observed by transmission electron microscopy following the frontal section. RESULTS: The flat preparation revealed the corneal fibroblasts between the lamellae of the collagen fibers and showed that the ramifying cellular processes of the keratocytes were in contact with the cytoplasmic processes or cell bodies of neighboring fibroblasts. Two types of discrete subpopulations of keratocytes were identified: a smaller, cellular type of keratocyte with spindle-shaped nucleus with heterochromatin, and a larger, cellular type with a large indented nucleus with relatively scanty cytoplasm. Collagen fibers ran parallel to each other toward the fenestration of the cytoplasmic wall of the keratocyte. CONCLUSIONS: These flat preparation method results showed that the keratocytes within the corneal stroma are interconnected with the adjacent keratocytes, which indicates the presence of a functional communicating network through the keratocyte circuits within the stroma. A smaller, cellular type of keratocyte with spindle-shaped nucleus was morphologically differentiated from a larger, cellular type with a large, indented nucleus by flat preparation and transmission electron microscopy.

The Cellular Characteristics of the Secondary Pupillary Membrane

PURPOSE: This study was performed to investigate the cellular characteristics of the secondary pupillary membrane. METHODS: The secondary pupillary membrane was removed from the anterior lens surface during cataract extraction from 2 patients with cataract associated with uveitis. Specimen from one patient was stained with hematoxylin-eosin with flat preparation method. Specimen from the other patient cultured for 1 and 2 weeks was observed with transmission electron microscopy. RESULTS: The flat preparation showed the neovascular membrane with pigment-laden cells. The cultured cells consisted of the well preserved vascular components which had the vascular endothelial cells and pericyte and pigment-laden cells lined by basement membrane on first week of culture. The iris pigment epithelial cell which contained the pigment granules within cytoplasm and lined by basement membrane were observed on second week of culture. CONCLUSIONS: These results suggest that the secondary pupillary membrane consists of vascular membrane and pigment epithelial cell of iris which is a major component of secondary pupillary membrane and secrets extracellular matrix.

Morphological Changes of Retinal Vessel Under Tissue Culture

PURPOSE: This study was performed to investigate the growth pattern of the retinal vessel including retinal vascular endothelial cell and pericyte. METHODS: The sensory retina was detached from the eyecup obtained from donor's eye. The retinal vessel which was separated from the sensory retina was cultured in tissue culture media for 2, 3 and 4 weeks separately and examined by transmission electron microscopy. RESULTS: On the second week of tissue culture, both the retinal vascular endothelial cells and pericyte were intact in morphology in nuclear and cytoplasmic pattern. Both cells were partially detached from the surrounding basement membrane. On the third week of tissue culture, the cytoplasm of the retinal vascular endothelial cells and pericyte were degenerated, whereas the vascular endothelial cell were intact in nuclear and cytoplasmic profiles which were still partially surrounded by the basement membrane. CONCLUSIONS: These findings suggest that the survivability of the retinal vascular endothelial cells and pericyte may be limited for 2 and 3 weeks, separatedly under the ordinary culture medium.

The Use of Ascorbic Acid after Excimer Laser Photo refractive Keratectomy in Rabbits

Polymorphonuclear leukocytes(PMNs) infiltrate to the wound site within a few hours after excimer laser photorefractive keratectomy(PRK). Oxygen free radicals produced by the PMNs may be injurious to the surrounding corneal tissues and also acts as an inflammatory mediator that deepen tissue damage. In this study we examined that the application of ascorbic acid would decrease corneal haze following excimer laser PRK. Excimer laser PRK was done in 9 rabbits (18 eyes). Ascorbic acid was injected subconjunctivally in one eye and BSS was injected in the opposite eye. The corneal epithelium re-surfaced by 2.6 +/- 0.5 days in the ascorbic acid treated group and by 2.7 +/- 0.7 days in the ESS injected group. Corneal hazes examined in postop 2wk, 4 wk, 6 wk, and 8 wk were 1.6 +/- 0.5, 1.4 +/- 0.5, 0.7 +/- 0.3, 0.5 +/- 0.2 in the ascorbic acid treated group and 2.1 +/- 0.6, 1.7 +/- 0.5, 1.1 +/- 0.3, 0.9 +/- 0.2 in the BSS injected group, respectively. These data suggest that ascorbic acid would decrease corneal haze after excimer laser PRK without significant complications.

Clinical Results of Phacoemulsification with Scleral Pocket Incision in Diabetic Patients

We compared the visual outcome after phacoemulsification through the scleral pocket incision between non-diabetic patients and diabetic patients, and studied the factors influencing the visual outcome and postoperative complications in diabetic patients. retrospectively. The subjects operated by one of the authors were composed of 277 non-diabetic patients (277 eyes) and 90 diabetic patients (113 eyes). An average of the best corrected visual acuities at postoperative 8 weeks was lower in diabetic patients than that in non-diabetic patients, but there was no statistically significant difference between diabetic patients who had no or background diabetic retinopathy and non-diabetic patients. In diabetic patients the visual outcome was significantly related with severity of diabetic retinopathy, duration of the diabetes, and insulin dependency, but not related with the rupture of posterior capsule during surgery. Among the complications there were posterior capsule rupture (10.6%), hyphema (7.8%), posterior capsular opacity (4.9%), and posterior synechiae (4.9%).