[Possibilities and limitations of glaucoma surgery]

Ultrasound cycloplasty in Chinese glaucoma patients: Results of a 6-month prospective clinical study

PURPOSE

The aim of this study was to evaluate the short-term efficacy and safety of ultrasound cycloplasty (UCP) procedure in Chinese glaucoma patients.

METHODS

As a single-centre, prospective, non-comparative study, 23 eyes of 23 patients suffering from glaucoma with uncontrolled intraocular pressure (IOP) ≥ 21 mmHg underwent a multi-dose UCP treatment with the activations of 6, 8 or10 sectors. Types of glaucoma include primary open-angle glaucoma (POAG) (7/23), primary angle closure glaucoma (PACG) (9/23) and secondary glaucoma (SG) (7/23). A complete ophthalmic examination including intraocular pressure (IOP) measurements was performed before UCP procedure and at 1 day, 1 month, 3months and 6 months after the procedure. An IOP reduction of ≥20% and IOP > 5 mmHg without increasing hypotensive medication at the follow-up visit was defined as therapeutic success. The post-operative complications were also recorded and compared to baseline for safety evaluation.

RESULTS

The mean baseline IOP of 23 treated eyes was 37.2 ± 12.1 mmHg. The IOP reduction after UCP procedure were 23%, 49%, 33% and 34% at 1 day, 1 month, 3 months and 6 months, respectively. Thus, the corresponding overall therapeutic success rates reached 61% (14/23), 83% (19/23), 65% (15/23) and 61% (14/23), respectively. Baseline IOPs of 8 and 10 sectors group (37.0 ± 9.9 mmHg and 50.1 ± 12.2 mmHg) were significantly higher than that of 6 sectors group (30.1 ± 8.2 mmHg). Therapeutic success rates of 6, 8 and 10 sectors groups reached 44% (4/9), 56% (5/9) and 100% (5/5), respectively. There were the highest percentage of IOP reduction (50% and 41%) and therapeutic success rate (6/7; 86% and 7/9; 78%) in SG group and PACG groups respectively. In addition, pre-operative ocular pain symptoms of four patients were all disappeared within one week after UCP. No serious intra-operative or post-operative complications occurred.

CONCLUSION

UCP procedure is an effective and well-tolerated treatment to reduce IOP in Chinese glaucoma patients, which offered a novel alternative for glaucoma treatment.

[Anti-scarring effect of rapamycin following filtering surgery in rabbit eyes]

OBJECTIVE

To study the effect of rapamycin on scar formation in rabbit eyes following filtering operation and explore the possible mechanism.

METHODS

Ninety-six healthy adult rabbits were subjected to trabeculectomy of the left eye and subsequently randomly divided into 4 groups (n=24) for treatment with castor oil (control) or rapamycin (1%, 3%, or 5%) eye drops of the operated eyes 4 times a day. The morphology and function of the filtering blebs of the rabbits were compared at 7, 14, 21 and 28 days after the operation; at each of the time points, 6 rabbits from each group were euthanized for detection of expressions of proliferating cell nuclear antigen (PCNA) and α-smooth muscle actin (α-SMA) in the tissues in the surgical area using immunohistochemistry. Cultured rabbit subconjunctival fibroblasts (RTFSs) were treated with different concentrations of rapamycin (0.06, 0.25, 1, and 4 mg/L) and the cell apoptosis was detected using flow cytometry.

RESULTS

In the first, second and third weeks after the operation, the rate of functional follicle formation was significantly higher in the 3 rapamycin groups than in the control group (P < 0.05), and the number of α- SMA-positive fibroblasts decreased over time in the 3 rapamycin groups. In cultured RTFSs, treatment with rapamycin at different concentrations resulted in increased apoptosis of the cells, and rapamycin above 0.25 mg/L significantly increased the cell apoptosis in a dose-dependent manner.

CONCLUSIONS

Rapamycin can inhibit hyperplasia of the filtering passage tissue, helps to preserve the functional filtering blebs and prolong their life span, and induces apoptosis of RTFS.

[Hyaluronic acid gels for pressure regulation in glaucoma treatment]

BACKGROUND

The increasing numbers of glaucoma patients and complications occuring during treatment, such as restenosis and hypotony, require new treatment options to prevent blindness in patients. Therefore, the abovementioned problems should be solved to prolong the lifetime of implants and to prevent repeated surgery.

OBJECTIVE

Can a novel stent with hyaluronic acid hydrogels (HA gel) as a functional unit be used to regulate pressure in glaucoma therapy in the long term?

MATERIAL AND METHODS

Model stents were filled with HA gels and it was investigated if these could regulate the pressure and what the underlying mechanism is.

RESULTS

The results of the investigations showed that the HA gel inside the stent functions as a pressure valve. Under certain equilibrium pressures the HA gel closes the stent and therefore retains the fluid. At a certain overpressure the HA gel enables the fluid to be released and leads to a self-regulated adjustment of the equilibrium pressure.

DISCUSSION

The next step will involve miniaturization of the stents. Experiments will then show if the valve function will also work in the dimensions necessary for an eye implant and if the current problem of hypotension in glaucoma therapy can be solved.