Retinal changes were evaluated after vitreous replacement with perfluorodecalin. Tolerance to this liqued in rabbit eyes was investigated for peiod of 1 month.

Histologic examination revealed degeneration the loss of the outer segment of the photoreceptors, decreased thickness of the outer retinal layers and in the vitreous These changes were progressed with the longer duration of the intravitreal replacement of perfluorodecalin. From the above resulgts, perfluorodecalin is thought to be unsuttable for the long-term witreous substitute and should be removed from the wyw before the vompletion of surgery.

Anionic sites are thought to act as anionic barriers regulating passage of proteins across Bruch's membrane of the eye. The cationic electron microscope tracer. polyethyleneimine (PEI), was used to study the distribution of the anionic sites in the Bruch's membrane of the control rabbit eyes and sodium iodate injected eyes. In Bruch's membrane of the control eyes, electron dense particles are present along the both sides of the basal lamina of the RPE and choriocapillaris and along collagen and elastic fibers. In the sodium iodate treated eyes, the RPE cells are severely degenerated and anionic sites are significantly decreased in the Bruch's membrane. These changes suggest that RPE cells play an important role in maintaining the anionic sites in the Bruch's membrane.

To evaluate the effects of the anterior retinal cryopexy on the absorption of the vitreous hemorrhage. vitreous hemorrhage was induced in 27 rabbit eyes. 0.1ml of autologous venous blood was injected into the vitreous through the sclera 3mm posterior to the corneoscleral limbus with 26 gauze needle. Anterior retinal cryopexy was applied on the sclera anterior to the equator(15 eyes). The treatment consisted of 24 cryopexy applications, applied 360° transconjunctivally between the ora serrata and equator. Cryopexy was not applied in the control eyes(12 eyes).

The Results were as follows :

1) Vitreous hemorrhage was completely absorbed in 2/12 eyes in the control group. and 8/13 eyes in the treated group during the observation period.

2) There was no statistically significant difference in the period that the vitreous was cleared to Grade I opacity beteween the control and treated groups.

3) Cataract was developed in the 2 eyes of treated group 5 weeks after anterior retinal cryopexy.