Evaluation of the effects of hydrodissection with antimitotics using a rabbit model of Soemmering's ring formation

Influence of intraocular lens implantation on anterior capsule contraction and posterior capsule opacification

PURPOSE

To evaluate whether and how intraocular lens (IOL) implantation influences the development of anterior capsule contraction and posterior capsule opacification (PCO).

SETTING

Department of Ophthalmology, Dokkyo Medical University, Mibu, Tochigi, Japan.

DESIGN

Experimental study.

METHODS

Phacoemulsification was performed in 8-week-old white rabbits. A hydrophobic acrylate IOL (12.5 mm) (YA-60BBR) was implanted in 1 eye and no IOL was implanted in the fellow eye. Slitlamp microscopy and anterior segment analysis were performed to evaluate anterior capsule contraction after the surgery. Four weeks postoperatively, sections of the eyes were made, and the thickness of the proliferated lens epithelial cell (LEC) layer at the posterior capsule was measured to assess the PCO. In addition, LECs from white rabbits were cultured in medium containing 50% aqueous humor or in medium containing 50% saline to determine the influence of the aqueous humor on LECs and to compare the degree of LEC proliferation.

RESULTS

Starting 2 weeks after surgery, anterior capsule contraction progressed more significantly in the IOL group than in the group without IOLs. Four weeks postoperatively, LEC thickness at the posterior capsule was significantly less in the group without IOLs than in the IOL group. In the culture study, LEC proliferation was more inhibited in the aqueous humor group than in the saline group.

CONCLUSIONS

Progression of anterior capsule contraction and PCO is less likely in aphakic eyes than in IOL-implanted eyes. The mechanism of prevention may involve aqueous humor-induced inhibition of LEC proliferation.

Effect of H-7 on secondary cataract after phacoemulsification in the live rabbit eye

PURPOSE

This study is aimed to determine if the serine-threonine kinase inhibitor H-7 inhibits secondary cataract after phacoemulsification in the live rabbit eye.

METHODS

Eighteen rabbits underwent extracapsular lens extraction by phacoemulsification in 1 eye. The eye was treated with intravitreal H-7 (300 or 1,200 μM; n = 6 or 5) or balanced salt solution (BSS) (n = 7) immediately after the surgery and twice weekly for 10 weeks. Each eye received slit lamp biomicroscopy once a week, during which posterior capsule opacification (PCO) was evaluated. The eye was then enucleated and the lens capsule was prepared, fixed, and imaged. PCO was evaluated again on the isolated lens capsule under a phase microscope. Soemmering's ring area (SRA) and the entire lens capsule area were measured from capsule images on a computer and the percentage of SRA (PSRA) in the entire capsule area was calculated. Wet weight of the capsule (WW) was determined on a balance.

RESULTS

No significant difference in PCO was observed in any comparison. No significant differences in SRA, PSRA, and WW were observed between the 300 μM H-7-treated eye and the BSS-treated eye. However, SRA, PSRA, and WW in the 1,200 μM H-7-treated eye were significantly smaller than those in the BSS-treated eye [28.3 ± 16.2 vs. 61.4 ± 8.86 mm(2) (P = 0.001), 33% ± 20% vs. 65% ± 15% (P = 0.01), and 65.6 ± 27.9 vs. 127.0 ±37.3 mg (P = 0.01)].

CONCLUSIONS

Intravitreal H-7 (1,200 μM) significantly inhibits Soemmering's ring formation in the live rabbit eye, suggesting that agents that inhibit the actomyosin system in cells may prevent secondary cataract after phacoemulsification.

Safety of irrigation with 5-fluorouracil in a sealed-capsule irrigation device in the rabbit eye

PURPOSE

To study the safety of irrigation with 5-fluorouracil (5-FU) in the Perfect Capsule sealed-capsule irrigation device (Milvella, Ltd., Epping, Australia).

SETTING

St. Erik's Eye Hospital, Stockholm, Sweden.

METHODS

Thirty 8-week-old rabbits were divided into 4 groups. Clear lens extraction was performed and the Perfect Capsule was applied in 1 eye in Groups 1, 2 and 3. The sealed system was flushed with balanced salt solution (BSS) in Group 1, 5-FU 50 mg/mL in Group 2, and 5-FU followed by BSS in Group 3. In Group 4, the Perfect Capsule was not applied; instead, 0.2 mL of 5-FU was instilled in the capsule and left there for 30 seconds. An endothelial cell count and pachymetry were performed preoperatively and 24 hours postoperatively. At 24 or 48 hours (half of each group at each time point), the rabbits were killed and the retina and trabecular meshwork histopathologically examined. The endothelial cell count and pachymetry were compared between the Perfect Capsule eye and the control eye in Group 1.

RESULTS

There was no difference between the groups in endothelial cell count (P = .96) or pachymetry (P = .32). Histologic evaluation showed no damage from the 5-FU. The comparison between eyes in Group 1 showed that the use of the Perfect Capsule did not cause more endothelial cell loss (P = .86) or increase pachymetry more (P = .28) than in the control eye.

CONCLUSION

Irrigation with 5-FU 50 mg/mL in the sealed-capsule irrigation device was safe and caused no apparent damage to the adjacent intraocular tissues.