Refractive status and histological changes after posterior scleral reinforcement in guinea pig

Abstract

Aim: To investigate the refractive and the histological changes in guinea pig eyes after posterior scleral reinforcement with scleral allografts.

Methods: Four-week-old guinea pigs were implanted with scleral allografts, and the changes of refraction, corneal curvature and axis length were monitored for 51d. The effects of methylprednisolone (MPS) on refraction parameters were also evaluated. And the microstructure and ultra-microstructure of eyes were observed on the 9d and 51d after operation. Repeated-measures analysis of variance and one-way analysis of variance were used.

Results: The refraction outcome of the implanted eye decreased after operation, and the refraction change of the 3 mm scleral allografts group was significantly different with control group (P=0.005) and the sham surgical group (P=0.004). After the application of MPS solution, the reduction of refraction outcome was statistically suppressed (P=0.008). The inflammatory encapsulation appeared 9d after surgery. On 51d after operation, the loose implanted materials were absorbed, while the adherent implanted materials with MPS group were still tightly attached to the recipient's eyeball.

Conclusion: After implantation of scleral allografts, the refraction of guinea pig eyes fluctuated from a decrease to an increase. The outcome of the scleral allografts is affected by implantation methods and the inflammatory response. Stability of the material can be improved by MPS.

Keywords: guinea pig; inflammation; methylprednisolone; myopia; posterior scleral reinforcement.

Figure 1. Experimental design and animal grouping.

Figure 2. Refractive status changes after implantation of scleral allografts in guinea pig in 51d

A: The refraction changes; B: The difference of binocular eyes refraction, the right eye of the group A was taken as control; C: The changes of cornea curvature; D: Axial length; E: Lens thickness; F: Vitreous chamber depth postoperatively. Group A: Untreated control group; Group B: Sham surgery group; Group C: 2 mm material group; Group D: 3 mm material group. Statistics were represented by mean±SEM. n=10.

Figure 3. Effect of the MPS on refractive status of guinea pig eyes after operation

A: The changes of refraction; B: The refraction changes postoperative in 51d; C: Axial length; D: Vitreous chamber depth with MPS or saline injection 9d after operation. The curves were presented as the difference between postoperative refraction and the baseline refraction value on the 0d. Group A: Untreated control group; Group D: 3 mm material group; Group E: MPS group; Group F: 3 mm material+MPS group; Group G: 3 mm material+saline group. Statistics were represented by mean±SEM. n=10, ^aP<0.05. MPS: Methylprednisolone.

Figure 4. Scleral graft of group D, F, G, and H 9d after operation (100× and 400×)

Group D: 3 mm material group; Group F: 3 mm material+MPS group; Group G: 3 mm material+saline group; Group H: 3 mm material loose implantation group. Scale bar=100 µm. MPS: Methylprednisolone.

Figure 5. Scleral graft of group D, F, G, and H 51d after operation (100× and 400×)

Group D: 3 mm material group; Group F: 3 mm material+MPS group; Group G: 3 mm material+saline group; Group H: 3 mm material loose implantation group. Scale bar=100 µm. MPS: Methylprednisolone.

Figure 6. Ultrastructural observation after implantation of scleral allografts

A, B: The swelling collagen of scleral graft (A) and recipient's sclera (B) 9d postoperatively (20 000×); C: The fibroblast with pigment granules and lysosomes in the encapsulation (8000×); D: The new collagen and macrophages with pseudopodia (30 000×); E: The macrophages with lysosomes (60 000×); F: The fibroblast with lysosomes in it (15 000×); G: The lysosomes near the fibroblast (30 000×); H: The fibroblast with plentiful endoplasmic reticulum and Golgi body (30 000×); I: The fibroblast with pigment granules of the graft sclera 51d postoperatively (20 000×). Scale bar=1 µm.