Relationship of diabetic microvascular complications to outcome in panretinal photocoagulation treatment of proliferative diabetic retinopathy

Proliferative diabetic retinopathy without preoperative pan-retinal photocoagulation is associated with higher levels of intravitreal IL-6 and postoperative inflammation

Purpose

Intravitreal cytokine levels and differences in the severity of postoperative inflammation in patients with proliferative diabetic retinopathy (PDR) were compared between subjects treated with pan-retinal photocoagulation (PRP) prior to undergoing vitreous surgery and those treated similarly during the surgery.

Subjects and methods

We examined 130 eyes of PDR patients who underwent an initial surgical procedure at Hirosaki University Hospital. A total of 67 out of the 130 eyes were treated with PRP prior to surgery (preoperative group), while 63 underwent similar treatment during surgery (intraoperative group). Vitreous fluid was collected at the start of the vitreous surgical procedure. Following vitrectomy, intraoperative PRP was completed during the surgery in the intraoperative group. This procedure was added to the peripheral part as needed in the preoperative group. The results for the levels of 27 cytokines, including vascular endothelial growth factor (VEGF), were measured using multiplex assays and compared between the groups. For determining postoperative inflammation, eyes in which fibrin was observed for 3 days or longer in the anterior chamber or vitreous cavity were considered to have fibrin deposition. The rate of fibrin deposition was compared between these groups.

Results

Among the vitreous cytokines examined, there was no significant difference in the VEGF levels between the groups (p = 0.70). In contrast, the IL-6 level was significantly higher in the intraoperative group (2813.2 ± 6022.2 vs. 1248.5 ± 1442.2 pg/ml, p = 0.048). Furthermore, the fibrin deposition rate was significantly higher in the intraoperative (44.4%) versus the preoperative group (14.9%) (p = 0.0002).

Conclusion

Severe postoperative inflammation was frequently seen in patients who did not undergo preoperative PRP, which may have been due to the performance of the procedure during the surgery. Moreover, these results may also be associated with a higher level of intravitreal IL-6.

Study of clinical applications and safety for Pascal® laser photocoagulation in retinal vascular disorders

PURPOSE

To establish safe laser parameter standards for 10-30 ms Pascal(®) laser in clinical practice and to evaluate clinical and visual outcomes using this 532-nm multi-spot photocoagulation system.

METHODS

Retrospective observational case series of 313 patients treated between 2006 and 2008. Evaluation of eight groups: A - panretinal photocoagulation (PRP) for proliferative diabetic retinopathy (PDR); B - focal laser treatment for clinically significant diabetic macular oedema; C - grid laser for diffuse diabetic macular oedema; D - sector PRP for ischaemic branch retinal vein occlusions (I-BRVO); E - full PRP for ischaemic central retinal vein occlusions (I-CRVO); F - macular laser treatment for macular oedema secondary to non-ischaemic BRVO; G - full PRP for rubeosis iridis and/or neovascular glaucoma (NVG) secondary to I-BRVO, I - CRVO or PDR; H - laser retinopexy for retinal breaks/degenerations.

RESULTS

Mean LogMAR visual acuity for all procedures improved postlaser (p = 0.065), and laser prevented visual loss in 85% eyes. Topical anaesthesia was only required. At mean follow-up of 5 months, 72% procedures had a successful clinical outcome. Significantly higher powers were required for PRP using Pascal(®) compared to conventional laser (p = 0.001) in PDR, I-BRVO, I-CRVO and NVG. Sixty-seven per cent of patients (15/20) were successfully treated with single-session 20-ms PRP using a mean 1952 burns. There were no laser-associated adverse effects or ocular complications associated with multi-spot PRP or macular Pascal(®) arrays.

CONCLUSIONS

The clinical efficacy using 10- to 30-ms pulse duration Pascal(®) laser is comparable to conventional standard protocols used for the treatment of vascular retinal disorders. Higher power, 10- to 30-ms pulse duration laser may be safely and effectively used in clinical practice.

Panretinal photocoagulation for proliferative diabetic retinopathy: pattern scan laser versus argon laser

PURPOSE

To evaluate the efficacy of the pattern scan laser (PASCAL) in treating newly diagnosed high-risk proliferative diabetic retinopathy (PDR).

DESIGN

Retrospective comparative case series.

METHODS

SETTING

Institutional.

STUDY POPULATION

Eighty-two consecutive eyes of the same number of patients with newly diagnosed high-risk PDR treated with panretinal photocoagulation (PRP) using either argon green laser (41 eyes treated before February 2007) or PASCAL (41 eyes treated February 2007 or thereafter), then followed for at least 6 months.

PROCEDURE

Retrospective chart review with attention to main outcome measures, age, sex, race, follow-up interval, insulin dependence, hemoglobin A1c, and total number of lasers spots.

MAIN OUTCOME MEASURES

Persistence or recurrence of neovascularization, incidence of vitreous hemorrhage (VH), neovascularization of the iris (NVI), neovascular glaucoma (NVG), and need for vitrectomy.

RESULTS

Patients treated with the PASCAL and argon laser received a similar number of spots (1438 vs 1386; P = .59). Patients treated with the PASCAL were more likely to experience persistence or recurrence of neovascularization within 6 months of initial treatment (73% vs 34%; P < .0008). The study was not adequately powered to detect a significant difference in incidence of vitreous hemorrhage, NVI, NVG, or need for vitrectomy.

CONCLUSIONS

When using traditional laser settings, PRP performed with the PASCAL is less effective than that performed with traditional argon laser in effecting lasting regression of retinal neovascularization in the setting of previously untreated high-risk PDR. Physicians may need to change treatment parameters when using PASCAL pattern laser therapy for high-risk PDR.

Experience with the Pascal® photocoagulator: an analysis of over 1,200 laser procedures with regard to parameter refinement

Aim:

To systematically refine and recommend parameter settings of spot size, power, and treatment duration using the Pascal^® photocoagulator, a multi-spot, semi-automated, short-duration laser system.

Materials and Methods:

A retrospective consecutive series with 752 Caucasian eyes and 1242 laser procedures over two years were grouped into, (1) 374 macular focal / grid photocoagulation (FP), (2), 666 panretinal photocoagulation (PRP), and (3) 202 barrage photocoagulation (BP). Parameters for power, duration, spot number, and spot size were recorded for every group.

Results:

Power parameters for all groups showed a non-gaussian distribution; FP group, median 190 mW, range 100 – 950 mW, and PRP group, median 800 mW, range 100 – 2000 mW. On subgroup comparison, for similar spot size, as treatment duration decreased, the power required increased, albeit in a much lesser proportion than that given by energy = power × time. Most frequently used patterns were single spot (89% of cases) in FP, 5 × 5 box (72%) in PRP, and 2 × 2 box (78%) in BP. Spot diameters as high as ≈ 700 μm on retina were given in the PRP group. Single session PRP was attempted in six eyes with a median spot count of 3500.

Conclusion:

Overall, due to the small duration of its pulse, the Pascal^® photocoagulator tends to use higher powers, although much lower cumulative energies, than those used in a conventional laser. The consequent lesser heat dissipation, especially lateral, can allow one to use relatively larger spot sizes and give more closely spaced burns, without incurring significant side effects.

Pascal laser versus conventional laser for treatment of diabetic retinopathy

PURPOSE

To compare the safety and efficacy of Pascal laser photocoagulation in comparison with the conventional laser photocoagulation in the treatment of diabetic retinopathy.

PATIENTS AND METHODS

A prospective randomized case series study was done on 120 procedures done in 120 patients divided into two main groups, group A, patients undergoing focal or modified grid macular laser and group B, patients undergoing panretinal photocoagulation (PRP). Each of the two groups were subdivided into two subgroups randomly in the first we used conventional laser photocoagulation (groups A1 and B1) and in the other we used Pascal laser photocoagulation (groups A2 and B2).

RESULTS

Procedures in groups A1,2 and in groups B1,2 had successful outcomes. Significantly higher powers were required with the Pascal (groups A2 and B2) than with conventional laser (groups A1 and B1) (p < 0.001) in eyes that underwent PRP and focal/modified grid macular treatment with both systems. No adverse events were noted in all groups.

CONCLUSION

The Pascal photocoagulator is safe, rapid, effective, with rapid learning and had short exposure time. Although the shorter pulse duration of the Pascal necessitates the use of a higher power, it is not associated with adverse effects.

Initial experience with the Pascal photocoagulator: a pilot study of 75 procedures

Background:

The Pascal is a semiautomated photocoagulator that delivers a pattern array of multiple burns in a rapid predetermined sequence with a single foot pedal depression. Each burn is reduced to 10 or 20 ms to achieve this. The authors report their early experience with this system.

Methods:

75 procedures done in 60 patients divided into four groups—group A, patients undergoing panretinal photocoagulation (PRP); group B, patients undergoing focal or modified grid macular laser; group C, patients undergoing macular grid and group D, patients undergoing retinopexy—were retrospectively studied.

Results:

31/34 procedures in group A, 24/26 procedures in group B, 5/7 procedures in group C and all eight patients in group D had successful outcomes. Significantly higher powers were required with the Pascal than with conventional laser (p<0.001) in eyes that underwent PRP and focal/modified grid macular treatment with both systems. Single session PRP was successfully performed in five patients, and five were successfully treated with a macular grid using pattern arrays only. No adverse events were noted.

Conclusion:

Although the shorter pulse duration of the Pascal necessitates the use of a higher power, it is not associated with adverse effects. The results here suggest that the Pascal photocoagulator is safe and effective, and offer several potential advantages related to the brief exposure time.

Delivery of photocoagulation treatment for diabetic retinopathy at a large Australian ophthalmic hospital: comparisons with national clinical practice guidelines

OBJECTIVE

To determine if the delivery of photocoagulation for diabetic retinopathy at a large Australian ophthalmic hospital conforms with Australian National Health and Medical Research Council clinical practice guidelines.

METHODS

A retrospective medical record review was conducted of all patients who had initial laser treatment for diabetic retinopathy at the Royal Victorian Eye and Ear Hospital from January 1997 to December 1998.

RESULTS

The study included 322 eyes from 203 patients. The mean age was 65.8 years (range 18-89 years) and the mean duration of diabetes was 14.7 years (range 1-40 years). Panretinal photocoagulation (PRP) alone was performed in 37 eyes over a mean number of 2.6 sessions. The median waiting time for these procedures was 14 days (range 0-146 days) and the median follow-up time was 7.1 weeks (range 1-25 weeks). Focal treatment was performed (without PRP) in 238 eyes and 55.5% of these cases required repeat focal treatment for persistent clinically significant macular oedema. Median waiting time for focal treatment was 20 days (range 0-302 days) and the median follow-up time after treatment was 12.1 weeks (range 1.7-42.0 weeks). Focal and PRP treatment was used in 47 eyes that had maculopathy concurrently with proliferative retinopathy. Focal treatment was applied before (or at the same session as) the PRP wherever possible.

CONCLUSIONS

The study indicates that the application of photocoagulation and follow up for diabetic retinopathy at this tertiary referral institution conforms closely with Australian clinical practice guidelines.

Clinical applications of the MicroPulse diode laser

PURPOSE

To evaluate the efficacy of the Iris Oculight MicroPulse 810 nm diode laser in the treatment of macular oedema secondary to either branch retinal vein occlusion (BRVO) or diabetic maculopathy and in the treatment of proliferative diabetic retinopathy. The specific advantages of this type of laser delivery are greater retinal pigment epithelial specificity and less damage to the inner retina, thus preserving visual field and colour contrast sensitivity.

METHODS

Fifty-two eyes of 33 consecutive patients were treated over a 6-month period. Thirteen eyes had proliferative diabetic retinopathy and 39 had macular oedema secondary to BRVO or diabetic maculopathy. Panretinal and grid pattern photocoagulation were performed using the micropulse mode with the laser on for 100-300 microseconds and off for between 1900 and 1700 microseconds repeatedly in a pulse envelope of 0.1-0.3 s duration. Microaneurysms were not treated directly. Patients were assessed clinically and angiographically at 3 and 6 months.

RESULTS

Ten eyes (77%) with proliferative disease showed some regression of new vessels at 6 months. Twenty-two eyes (57%) showed resolution of macular oedema at 6 months. Visual acuity was maintained in 27 eyes (69%) and improved in 11 eyes (28%).

CONCLUSION

Diode laser in micropulse mode is effective in the management of diabetic and occlusive macular oedema and proliferative diabetic disease.