Cyclophotocoagulation with the transscleral contact red 670-nm diode laser in the treatment of glaucoma

Quantitative systems pharmacology of the eye: Tools and data for ocular QSP

Good eyesight belongs to the most-valued attributes of health, and diseases of the eye are a significant healthcare burden. Case numbers are expected to further increase in the next decades due to an aging society. The development of drugs in ophthalmology, however, is difficult due to limited accessibility of the eye, in terms of drug administration and in terms of sampling of tissues for drug pharmacokinetics (PKs) and pharmacodynamics (PDs). Ocular quantitative systems pharmacology models provide the opportunity to describe the distribution of drugs in the eye as well as the resulting drug-response in specific segments of the eye. In particular, ocular physiologically-based PK (PBPK) models are necessary to describe drug concentration levels in different regions of the eye. Further, ocular effect models using molecular data from specific cellular systems are needed to develop dose-response correlations. We here describe the current status of PK/PBPK as well as PD models for the eyes and discuss cellular systems, data repositories, as well as animal models in ophthalmology. The application of the various concepts is highlighted for the development of new treatments for postoperative fibrosis after glaucoma surgery.

An update on continuous-wave cyclophotocoagulation (CW-CPC) and micropulse transscleral laser treatment (MP-TLT) for adult and paediatric refractory glaucoma

PURPOSE

Continuous-wave cyclophotocoagulation (CW-CPC) is often preferred to medical and surgical treatments for managing refractory glaucoma. This review summarizes diode CW-CPC indications, history, histopathology, methods, efficacy and safety. It also provides an overview of the latest data available on micropulse transscleral laser treatment (MP-TLT) that uses repetitive micropulses of diode laser energy in an off-and-on cyclical fashion.

METHODS

A literature review was conducted on transscleral CW-CPC (CW-TSCPC), endoscopic CPC (ECP) and MP-TLT. Relevant series of adult and paediatric patients were included for assessing the procedures.

RESULTS

Regarding CW-TCPC, highly variable success rates are reported in the literature, depending on the definition of success, type of underlying glaucoma, energy settings, follow-up duration and retreatment rates. CW-CPC often needs to be repeated, especially in paediatric patients. CW-CPC exposes to risks of inflammation and chronic ocular hypotony or phthisis with irreversible visual loss. CW-TSCPC has mainly been used in very severe forms of glaucoma, in painful eyes with limited visual potential or after filtering surgery failure. Published data on ECP are more limited but overall good success rates have been reported. Through the direct visualization of the targeted ciliary body in anatomically abnormal eyes, ECP is the preferred surgical procedure in paediatric refractory glaucoma. Complication rates are relatively low after ECP; however, large studies with long-term follow-up are needed. ECP may be used in difficult, refractory cases, but it is often used earlier when combined with cataract surgery. Despite limited data on the exact mechanism of action of MP-TLT and a lack of standardization of laser settings, the first data from heterogeneous case series shows that it has a similar efficacy and a better safety profile compared to CW-TSCPC in the medium term.

CONCLUSION

Although they may lead to sight-threatening complications, both CW-TSCPC and ECP seem effective. ECP appears to be superior to CW-TSCPC in paediatric refractory glaucoma. Unlike ECP combined with cataract surgery, evidence supporting a wider use of CW-TSCPC and MP-TLT in earlier stages of neuropathy is lacking. While it now appears that the safety profile of MP-TLT is superior to that of CW-CPC, robust prospective comparative studies including homogeneous and well-defined cohorts of patients are still needed to confirm an at least comparable efficacy in the long term.

Comparison of the safety and efficacy of triple sequential therapy and transscleral cyclophotocoagulation for neovascular glaucoma in the angle-closure stage

To compare the efficacy and safety of triple therapy combining intravitreal injection of anti-vascular endothelial growth factor, trabeculectomy, and pan-retinal photocoagulation via binocular indirect ophthalmoscopy, with that of transscleral cyclophotocoagulation (TCP) to treat neovascular glaucoma in the angle-closure stage. Eighteen triple therapy patients and 25 TCP patients between May 2014 and May 2016 were retrospectively analysed. Anterior chamber puncture and anti-VEGF intravitreal injection were performed on the first day of sequential therapy. Trabeculectomy was performed 3–5 d after injection; pan-retinal laser photocoagulation via binocular indirect ophthalmoscopy was initiated 5–7 d later. The IOP of the triple therapy group was lower than that of the TCP group (15.2 ± 2.2 vs. 20.0 ± 8.5 mmHg) and fewer anti-glaucoma drugs were used (0.5 ± 1.0 vs. 0.6 ± 1.0) after treatment. The success rates of the two groups were 89% and 60% respectively (P = 0.032). The visual function of 94% of triple therapy patients was preserved or improved compared to 64% of TCP patients with statistical significance (P = 0.028). No patient in the triple therapy group showed hypotony or eyeball atrophy. Compared to TCP, triple therapy shows higher success rate, fewer complications, and attributes to visual function preservation.

Intraocular Pressure Outcomes Following Transscleral Diode Cyclophotocoagulation Using Long and Short Duration Burns

PURPOSE

The purpose of this study was to compare outcomes of transscleral diode cyclophotocoagulation using short duration (SD) versus longer duration (LD) treatment.

PATIENTS AND METHODS

Data were collected retrospectively on patients with glaucoma who underwent cyclophotocoagulation with LD (4000 ms) treatment with variable power ≤1000 mW versus SD using 1500 ms with variable power ≤2000 mW. The outcome measures included: intraocular pressure (IOP) at 12 months, decrease in number of antiglaucoma medications, complications and visual acuity (VA) at the final follow-up visit.

RESULTS

There were 71 patients and 70 patients in the SD and LD groups, respectively. The mean IOP±SD pretreatment baseline was 33±10 versus 36±10 mm Hg for SD and LD groups, respectively (P>0.05). At 1 year postoperatively, the IOP decreased significantly in both groups (16.7 vs. 17.4 mm Hg for SD and LD, respectively; P<0.0001). This decrease in IOP was comparable between groups (P=0.5). The average number of IOP lowering medications were 2.5 and 2.9 at baseline in the SD and LD groups, respectively, and decreased to 1.3 in both groups (P=0.83). The mean LogMAR VA decreased significantly from 1.87 at baseline to 1.96 at 1 year in the SD group (P=0.276), and 2.03 to 2.3 (P≤0.001) in the LD group, this change was comparable (0.19; P=0.075) between the 2 groups. Complications were also comparable.

CONCLUSIONS

Both LD and SD burns during cyclophotocoagulation effectively lowered IOP at 1 year. Neither treatment resulted in a greater reduction of IOP. LD treatment appeared to result in a decrease in VA and greater postoperative inflammation.

Red laser cyclophotocoagulation in the treatment of secondary glaucoma in eyes with uveal melanoma

PURPOSE

To evaluate retrospectively the usefulness of the red diode and krypton laser for transscleral contact cyclophotocoagulation (CPC) in the treatment of secondary glaucoma in eyes with uveal melanoma.

PATIENTS AND METHODS

Twenty-seven eyes of 27 patients (mean age, 66 y; range, 33 to 85 y) with a uveal melanoma and secondary glaucoma were treated with a transscleral 670-nm diode (40 treatments) and 647-nm krypton (5 treatments) laser CPC; 25 eyes had been or were subsequently treated with brachytherapy. The energy used was 420 mW at the tip of the probe (exposure time, 10 s). Seventeen eyes were treated once, 6 eyes twice, and 4 eyes 3 to 6 times. The aim was to preserve vision in 21 patients and to relieve pain in 6 patients. Fourteen patients (52%) died during follow-up.

RESULTS

With ≥1 CPCs, the intraocular pressure decreased from a median of 40 mm Hg at baseline to 28 mm Hg at 12 months (n=18) and 23 mm Hg at 24 months (n=10). Hypotony developed in 6 eyes. Before CPC, 12 eyes had a best corrected visual acuity (BCVA) of 20/400 or better. At 12 months, 5 of 18 eyes had BCVA 20/400 or better, and at 24 months 4 of 10 eyes. Four eyes were removed. At the latest visit, 15 of 23 eyes had no light perception, but were preserved. All patients whose aim of treatment was to relieve pain achieved pain relief.

CONCLUSIONS

CPC lowered intraocular pressure and the number of medications needed for secondary glaucoma in eyes with uveal melanoma, also providing pain relief.