Due to the mechanical vulnerability of eyes that have undergone penetrating keratoplasty (PKP), it is clinically important to evaluate the possibility of corneal wound dehiscence by blunt impact. We have previously developed a simulation model resembling a human eye based on information obtained from cadaver eyes and applied three-dimensional finite element analysis (FEA) to determine the physical and mechanical response to an air gun impact at various velocities on the post-PKP eye. Methods: Simulations in a human eye model were performed with a computer using a FEA program created by Nihon, ESI Group. The air gun pellet was set to impact the eye at three-different velocities in straight or 12°up-gaze positions with the addition of variation in keratoplasty suture strength of 30%, 50% and 100% of normal corneal strength. Results: Furthermore to little damage in the case of 100% strength, in cases of lower strength in a straight-gaze position, wound rupture seemed to occur in the early phase (0.04-0.06 ms) of impact at low velocities, while regional break was observed at 0.14 ms after an impact at high velocity (75 m/s). In contrast, wound damage was observed in the lower quadrant of the suture zone and sclera in 12°up-gaze cases. Wound damage was observed 0.08 ms after an impact threatening corneoscleral laceration, and the involved area being larger in middle impact velocity (60 m/s) simulations than in lower impact velocity simulations, and larger damaged area was observed in high impact velocity cases and leading to corneoscleral laceration. Conclusion: These results suggest that the eye is most susceptible to corneal damage around the suture area especially with a straight-gaze impact by an air gun, and that special precautionary measures should be considered in patients who undergo PKP. FEA using a human eyeball model might be a useful method to analyze and predict the mechanical features of eyes that undergo keratoplasty.

Fungal conjunctivitis is a rare disorder, with low incidence and difficulty in diagnosis due to a lack of specific clinical findings. We report a case of fungal conjunctivitis which exhibited a specific clinical feature of giant papilla formation, and its diagnosis was a complex process. A 19-year-old woman with a history of atopic dermatitis and hard contact lens use was referred to us with a 3-month history of giant papillary conjunctivitis of the right eye in spite of treatment with antiallergic and corticosteroid eye drops, complicated by intraocular pressure elevation. The left eye showed no symptom of ocular surface disorder throughout the clinical course. The right eye did not respond to oral corticosteroid. Polymerase chain reaction of conjunctival scrapings against Chlamydia trachomatis was negative, and she was treated surgically by total papilla resection. Conjunctival giant papilla recurrence was not observed after surgery. Although the primary histopathological diagnosis was chronic inflammation due to atopic keratoconjunctivitis, repeated histopathological survey of excised conjunctival tissue including immunohistochemical staining revealed histiocytes, yeast type spores and hyphae, and phagocytosed spores and hyphae in macrophages. The causative organism was identified morphologically as a Candida species. Later, histopathological examination of a cervical swab revealed the presence of Candida sp. This rare case indicates that a fungal organism may underlie refractory conjunctivitis with specific giant papillary hypertrophy mimicking vernal keratoconjunctivitis.