Characteristics of corneal phospholipidosis induced by topical ocular application of chloroquine and amiodarone in rabbits

Repeatability of Corneal Densitometry Measurements using a Scheimpflug Camera in Healthy Normal Corneas

Purpose

To determine the repeatability of corneal densitometry measured by the Scheimpflug imaging system.

Methods

This cross-sectional study was conducted on photorefractive keratectomy candidates. One eye of each participant underwent imaging using Pentacam HR three times, 10 min apart. The repeatability of densitometry measurements was evaluated in four concentric annuli around the corneal apex and in different corneal depths. The repeatability of the measurements was evaluated using the intraclass correlation coefficient (ICC), repeatability coefficient (RC), and coefficient of variation (CV). The difference of repeatability between layers and zones was tested by tolerance index (TI).

Results

Sixty eyes of sixty patients with a mean age of 27.76 ± 3.93 years were studied. Half of the participants were female (n = 30, 50%). ICC was above 0.9 in all corneal parts. The posterior layer and central zones showed the least variability of densitometry measurements considering the CV values. The RC was 2.06, 1.17, and 0.92 in anterior, central, and posterior layers, respectively. The RC was 0.88, 0.71, 1.51, and 4.56 in 0-2, 2-6, 6-10, and 10-12 mm circles, respectively. Only the reliability of densitometry in 10-12 mm annulus was statistically lower than the central zone (TI = 0.71).

Conclusions

Corneal densitometry measurements provided by the Pentacam had good repeatability. The repeatability of densitometry measurements decreased from the center to the periphery (with an exception for 0-2 mm and 2-6 mm) and from the posterior to the anterior of the cornea. The reliability of the 10-12 mm zone was markedly less than other zones.

Pathological Features of Corneal Phospholipidosis in Juvenile White Rabbits Induced by Ocular Instillation of Chloroquine or Amiodarone

Cationic amphiphilic drugs (CADs) can induce phospholipidosis (PLD) in organs/tissues. Several ophthalmic pharmaceuticals containing CADs are marketed and used in children. To investigate the effect of PLD on the developing cornea, chloroquine and amiodarone, which are representative CADs, were applied topically to the eyes of juvenile rabbits, and the effects in juvenile rabbits were compared with those in young adult rabbits. Diffuse corneal cloudiness was observed in chloroquine- and amiodarone-treated eyes. Histopathologically, vacuolation was observed in the corneal epithelium and keratocytes. On ultrastructural examination, these vacuoles contained multilamellar inclusion bodies, which are a characteristic of PLD. The size of the vacuoles in the corneal epithelium was reduced in juveniles compared with young adults. Cytoplasmic lamellar bodies and exocytosis in the corneal endothelium were observed in young adult rabbits but not in juvenile rabbits. This study revealed that topical application of chloroquine or amiodarone induces corneal PLD in juvenile and young adult rabbits. Corneal endothelial changes occurred only in young adult rabbits, but ophthalmological changes were similar between juveniles and young adults. The results of the study suggest that the effects of corneal PLD were similar among age groups based on risk assessment.

Chloroquine as a possible disinfection adjunct of disinfection solutions against Acanthamoeba

Acanthamoeba keratitis is commonly encountered by contact lens wearers. Contact lens solution plays an important role in the safe use of contact lenses. The most popular products for disinfecting lenses are multipurpose disinfecting solutions (MPDS). However, almost all MPDS retailed in Korea are ineffective in killing Acanthamoeba. The objective of this study was to determine the possibility of using autophagy inhibitor chloroquine as a disinfecting agent to improve the amoebicidal activity of MPDS against Acanthamoeba, especially the cyst. Amoebicidal effects of eight different MPDSs combined with chloroquine (CQ), an autophagy inhibitor, and their cytotoxicities to human corneal epithelium cells were determined. Almost all MPDS showed strong amoebicidal effect on trophozoites after 8 h of exposure. However, they showed inadequate amoebicidal effect on cysts even after 24 h of exposure. MPDSs combined with 100 μM CQ increased their amoebicidal effects on immature cyst by inhibiting formation of mature cysts. Incubation with 100 μM CQ for 30 min did not have cytotoxicity to human corneal epithelial cells.