Pascal laser versus conventional laser for treatment of diabetic retinopathy

Treatment Outcome of Conjunctival Cyst Ablation by Pattern Scan Laser

PURPOSE

To evaluate the effectiveness of conjunctival cyst ablation using pattern scan laser photoablation.

METHODS

Ninety-four cases of symptomatic conjunctival cysts were included. After staining the surface of a conjunctival cyst with a dark-purple marker pen, an incision was made into the conjunctival cyst using a 26-gauge needle. Low-energy photoablation using 3 × 3 grids of spots was then applied around the incision site for a mean of 50 times. The laser spots were 400 μm in size, the power delivered ranged from 400 to 450 mW, and the duration of each laser pulse was 80 ms.

RESULTS

During a mean follow-up period of 6.5 months (range 6-16 months), 84 cases of conjunctival cysts (89.4%) were successfully corrected by conducting either 1 or 2 laser sessions. The cyst was completely resolved after a single laser session in 74 cases (78.7%). There were 20 cases of recurrence, which involved fixed, thick, and large cysts. The conjunctival cyst recurred again after the second laser session in 2 of the 12 eyes in which the procedure was repeated. The remaining 8 cases were observed without additional treatment. No postoperative complications such as conjunctival scarring or persistent ocular irritation were observed.

CONCLUSIONS

Pattern scan laser photoablation of a conjunctival cyst with the adjunctive use of cyst surface staining to increase the amount of thermal laser energy absorption is a simple and effective method for treating conjunctival cysts in an outpatient clinic.

Predictive factors associated with anatomical and functional outcomes following panretinal photocoagulation in people with proliferative diabetic retinopathy

PURPOSE

To determine effects of baseline characteristics and laser type performed on outcomes in people with proliferative diabetic retinopathy (PDR) undergoing panretinal photocoagulation (PRP).

METHODS

Medical records of all consecutive patients with PDR naïve to PRP, identified using an electronic database, evaluated at the Macula Clinic, Belfast Health and Social Care Trust, receiving their first PRP between 1st January 2016 and 30th June 2017, and followed for a minimum of 6 months following stabilization of PDR, were retrospectively reviewed. Outcomes included time to stabilization following PRP, progression of PDR, and mean change in best-corrected visual acuity from baseline to last follow-up. Cox regression was used to estimate hazard ratios (HRs) for the effect of baseline characteristics and type of laser on outcomes following treatment.

RESULTS

One hundred and fourteen patients (135 eyes) with a mean age of 57.6 (SD: 13.1) years were included, 67% males. People receiving pattern or mixed laser had a statistically significantly delayed stabilization (HR: 0.54, p=0.004; and HR: 0.41, p=0.001, respectively) and increased risk of progression (HR: 1.83, p=0.028; and HR: 2.04, p=0.018, respectively) when compared to those receiving standard laser. Among other potential predictors in multivariable regression analysis, only vitreous hemorrhage and fibrosis or traction at baseline increased risk of progression (HR: 1.70, p=0.017; and HR: 4.14, p<0.001 respectively). Baseline characteristics and type of laser had no statistically significant effect on vision.

CONCLUSION

These findings should be considered when selecting laser treatment, planning surveillance, and counselling patients with PDR undergoing PRP.

COMPARATIVE EVALUATION OF ANTERIOR SEGMENT OPTICAL COHERENCE TOMOGRAPHY, ULTRASOUND BIOMICROSCOPY, AND INTRAOCULAR PRESSURE CHANGES AFTER PANRETINAL PHOTOCOAGULATION BY PASCAL AND CONVENTIONAL LASER

PURPOSE

To compare intraocular pressure, anterior segment optical coherence tomography, and ultrasound biomicroscopy parameters over 3 months after panretinal photocoagulation (PRP) for proliferative diabetic retinopathy after 1 of 2 sittings by conventional laser (half PRP) and a single sitting of Pattern Scan Laser (PASCAL) PRP.

METHODS

This was a prospective, randomized, interventional study. All tests were performed at baseline, and at 1, 6, and 24 hours, and 1, 4, 8, and 12 weeks after PRP.

RESULTS

The intraocular pressure at 1 hour and 6 hours after PRP was significantly raised in both groups. Mean intraocular pressure was 21.17 ± 4.01 mmHg after PASCAL and 17.48 ± 3 mmHg after conventional laser at 1 hour, P < 0.001. On anterior segment optical coherence tomography, conventional laser PRP caused a more significant narrowing of angle-opening distance (AOD750) and trabecular-iris space area (TISA 500), P = 0.03 and 0.04, respectively, on Day 1. Ultrasound biomicroscopy showed a significantly narrow angle in both groups on Day 1. A significant increase in ciliary body thickness was observed in both groups, with 57.1% of PASCAL and 100% of conventionally treated eyes showing ciliary effusion on Day 1 that decreased but persisted for the next 3 months.

CONCLUSION

Performing PRP in sittings, prescribing previous glaucoma medications in patients at risk, and recording intraocular pressure an hour after the PRP could decrease complications.

Comparison of Pain Scores Among Patients Undergoing Conventional and Novel Panretinal Photocoagulation for Diabetic Retinopathy: A Systematic Review

PURPOSE

To summarize key findings from a systematic review focusing on pain as an adverse outcome of panretinal photocoagulation (PRP) among patients with diabetic retinopathy.

DESIGN

Systematic review.

METHODS

We systematically searched articles in major databases from July to September 2020. Studies that compared pain outcomes of PRP among diabetic patients who underwent conventional single-spot laser (SSL), conventional multi-spot laser (MSL), and/or novel navigated laser (NNL) were included. The Cochrane RoB 2 tool and ROBINS-I tool were used to evaluate the risk of bias of the included randomized controlled trials (RCTs) and controlled clinical trials (CCTs), respectively.

RESULTS

We included 13 RCTs and 4 CCTs. Thirteen studies were included for Comparison 1 (Conventional SSL versus Conventional MSL), 3 studies were included for Comparison 2 (NNL versus Conventional MSL), and 3 studies were included for Comparison 3 (NNL versus Conventional SSL). A total of 783 patients and 1961 eyes were included in this review. The review showed that NNL yielded the lowest pain scores, followed by conventional MSL, then by conventional SSL.

CONCLUSION

This review summarizes findings of multiple studies that reported pain as an adverse outcome of PRP among patients with advanced diabetic retinopathy. Data from RCTs with mostly some concerns for bias (RoB 2 tool) and CCTs with mostly moderate risk of bias (ROBINS-I tool) show benefit of using MSL over SSL, and NNL over conventional systems for PRP in diabetic retinopathy, considering pain as the primary outcome.

Choroidal Detachment Following Multi-spot Double Frequency Nd-YAG Retinal Photocoagulation - A Case Report

Introduction: Panretinal photocoagulation (PRP) remains the gold standard treatment for severe non-proliferative and proliferative diabetic retinopathy (PDR), as it reduces the risk of severe visual loss by more than 50%. In the conventional single-spot laser, the procedure involves the application of moderate-intensity burns of 200-500 microns, placed one spot-size apart to achieve a total of 1200-2000 applications in 2 or 3 sessions. The more advanced retina lasers like the Pattern Scan Laser (PASCAL) and the VITRA multi-spot laser are 532 nm frequency-doubled (Nd: YAG) solid-state lasers. These modern lasers enable the application of multiple laser burns in a rapid pre-determined sequence with reduced pulse duration (10-20 ms) to facilitate the PRP to be completed in a single sitting with lesser collateral tissue damage. Case Report: Though multi-spot lasers have significantly reduced the adverse events when compared with the conventional single-spot lasers, we report a case of rare adverse events (serous choroidal detachment) following PRP with the VITRA multi-spot double frequency NdYAG (532 nm) laser. Conclusion: Most of the serious choroidal detachments following PRP are self-limiting. We recommend complete retinal evaluation post laser procedure even with modern multisport laser to look for such adverse events.

Evaluation of Laser Effects on the Human Body After Laser Therapy

Lasers have wide applications in the treatment and diagnosis of diseases and various medical fields. Laser therapy like the other methods has advantages and disadvantages. Some risks such as bleeding, pain, and infection are created after laser therapy. Explanation and evaluation of laser effects on cell function, tissue, and the body are the aims of this study. We reviewed papers available from 1986 to 2019 about the effects of lasers on cells and tissue. An online search of PubMed, Science Direct and Google scholar using such keywords as "laser", "cell", "tissue", "body" and "side effects" was performed. The laser photons are absorbed by chromophores, resulting in the target heating and localized damage. Laser irradiation alters cellular metabolism and cellular functions. These alterations may be accompanied by undesired side effects which can be monitored via metabolites level change in the body. Based on this finding, laser therapy may be associated with several side effects and complications; therefore, before treatment, the determination of laser types and their properties is necessary to avoid creating side effects. The advantages and disadvantages of the treatment type should be considered in order to choose the best treatment with the least side effects. The patients' awareness of possible side effects before treatment and also an effective follow-up and management of patients after action are two important points in laser therapy. Training curriculum definition should be determined for laser applicant qualifications in different medical fields.

Single session of pattern scanning laser versus multiple sessions of conventional laser for panretinal photocoagulation in diabetic retinopathy: Efficacy, safety and painfulness

Purpose

To evaluate the clinical efficiency, safety and painfulness of retinal laser photocoagulation employing a pattern scanning laser system Pascal given in a single-session versus conventional laser multiple-session treatment of the same patient with diabetic retinopathy during 12-month follow-up.

Methods

The cohort included 60 eyes in 30 patients treated at the Ophthalmology Clinic, Faculty Hospital Ostrava, from 2008 to 2013. Panretinal laser coagulation was performed on one eye using the multispot panretinal photocoagulation given in a single-session system Pascal (OptiMedica, Santa Clara, California). On the other eye laser treatment was carried out by the classic conventional multiple-session method.

Results

The performance of Pascal panretinal laser coagulation was evaluated as significantly less painful (visual scale of pain was 3.28 ± 1.9) than the performance of conventional photocoagulation (visual scale of pain was 3.93 ± 1.88) with similar efficiency. Distribution of progression of diabetic retinopathy in individual patients was very similar in both groups under comparison, and was strictly paired in 24 of the 30 patients at the end of 1-year follow-up.

Conclusion

Laser photocoagulation of the retina with the use of short impulse durations and patterns in patients with diabetic retinopathy given in one session possesses similar efficiency to that of conventional retinal photocoagulation in multiple sessions. The single session treatment is also better tolerated by patients and in addition to this, it shortens the performance of the whole therapy, which potentially saves considerable funds of all subjects participating in the process of treatment.

Trial registration

ClinicalTrials.gov NCT03672656.

Different lasers and techniques for proliferative diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a chronic progressive disease of the retinal microvasculature associated with prolonged hyperglycaemia. Proliferative DR (PDR) is a sight-threatening complication of DR and is characterised by the development of abnormal new vessels in the retina, optic nerve head or anterior segment of the eye. Argon laser photocoagulation has been the gold standard for the treatment of PDR for many years, using regimens evaluated by the Early Treatment of Diabetic Retinopathy Study (ETDRS). Over the years, there have been modifications of the technique and introduction of new laser technologies.

OBJECTIVES

To assess the effects of different types of laser, other than argon laser, and different laser protocols, other than those established by the ETDRS, for the treatment of PDR. We compared different wavelengths; power and pulse duration; pattern, number and location of burns versus standard argon laser undertaken as specified by the ETDRS.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 5); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 8 June 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of pan-retinal photocoagulation (PRP) using standard argon laser for treatment of PDR compared with any other laser modality. We excluded studies of lasers that are not in common use, such as the xenon arc, ruby or Krypton laser.

DATA COLLECTION AND ANALYSIS

We followed Cochrane guidelines and graded the certainty of evidence using the GRADE approach.

MAIN RESULTS

We identified 11 studies from Europe (6), the USA (2), the Middle East (1) and Asia (2). Five studies compared different types of laser to argon: Nd:YAG (2 studies) or diode (3 studies). Other studies compared modifications to the standard argon laser PRP technique. The studies were poorly reported and we judged all to be at high risk of bias in at least one domain. The sample size varied from 20 to 270 eyes but the majority included 50 participants or fewer.Nd:YAG versus argon laser (2 studies): very low-certainty evidence on vision loss, vision gain, progression and regression of PDR, pain during laser treatment and adverse effects.Diode versus argon laser (3 studies): very-low certainty evidence on vision loss, vision gain, progression and regression of PDR and adverse effects; moderate-certainty evidence that diode laser was more painful (risk ratio (RR) troublesome pain during laser treatment (RR 3.12, 95% CI 2.16 to 4.51; eyes = 202; studies = 3; I² = 0%).0.5 second versus 0.1 second exposure (1 study): low-certainty evidence of lower chance of vision loss with 0.5 second compared with 0.1 second exposure but estimates were imprecise and compatible with no difference or an increased chance of vision loss (RR 0.42, 95% CI 0.08 to 2.04, 44 eyes, 1 RCT); low-certainty evidence that people treated with 0.5 second exposure were more likely to gain vision (RR 2.22, 95% CI 0.68 to 7.28, 44 eyes, 1 RCT) but again the estimates were imprecise . People given 0.5 second exposure were more likely to have regression of PDR compared with 0.1 second laser PRP again with imprecise estimate (RR 1.17, 95% CI 0.92 to 1.48, 32 eyes, 1 RCT). There was very low-certainty evidence on progression of PDR and adverse effects.'Light intensity' PRP versus classic PRP (1 study): vision loss or gain was not reported but the mean difference in logMAR acuity at 1 year was -0.09 logMAR (95% CI -0.22 to 0.04, 65 eyes, 1 RCT); and low-certainty evidence that fewer patients had pain during light PRP compared with classic PRP with an imprecise estimate compatible with increased or decreased pain (RR 0.23, 95% CI 0.03 to 1.93, 65 eyes, 1 RCT).'Mild scatter' (laser pattern limited to 400 to 600 laser burns in one sitting) PRP versus standard 'full' scatter PRP (1 study): very low-certainty evidence on vision and visual field loss. No information on adverse effects.'Central' (a more central PRP in addition to mid-peripheral PRP) versus 'peripheral' standard PRP (1 study): low-certainty evidence that people treated with central PRP were more likely to lose 15 or more letters of BCVA compared with peripheral laser PRP (RR 3.00, 95% CI 0.67 to 13.46, 50 eyes, 1 RCT); and less likely to gain 15 or more letters (RR 0.25, 95% CI 0.03 to 2.08) with imprecise estimates compatible with increased or decreased risk.'Centre sparing' PRP (argon laser distribution limited to 3 disc diameters from the upper temporal and lower margin of the fovea) versus standard 'full scatter' PRP (1 study): low-certainty evidence that people treated with 'centre sparing' PRP were less likely to lose 15 or more ETDRS letters of BCVA compared with 'full scatter' PRP (RR 0.67, 95% CI 0.30 to 1.50, 53 eyes). Low-certainty evidence of similar risk of regression of PDR between groups (RR 0.96, 95% CI 0.73 to 1.27, 53 eyes). Adverse events were not reported.'Extended targeted' PRP (to include the equator and any capillary non-perfusion areas between the vascular arcades) versus standard PRP (1 study): low-certainty evidence that people in the extended group had similar or slightly reduced chance of loss of 15 or more letters of BCVA compared with the standard PRP group (RR 0.94, 95% CI 0.70 to 1.28, 270 eyes). Low-certainty evidence that people in the extended group had a similar or slightly increased chance of regression of PDR compared with the standard PRP group (RR 1.11, 95% CI 0.95 to 1.31, 270 eyes). Very low-certainty information on adverse effects.

AUTHORS' CONCLUSIONS

Modern laser techniques and modalities have been developed to treat PDR. However there is limited evidence available with respect to the efficacy and safety of alternative laser systems or strategies compared with the standard argon laser as described in ETDRS.

Changes in pupil size following panretinal retinal photocoagulation: conventional laser vs pattern scan laser (PASCAL)

PurposeTo evaluate and compare the possible changes in pupil size subsequent to panretinal laser photocoagulation (PRP) via conventional laser and pattern scan laser (PASCAL).Patients and methodsForty eyes of 40 patients with diabetic retinopathy were included. 20 eyes had a PRP via conventional laser and formed Group 1. 20 eyes had a PRP via PASCAL laser and formed Group 2. The participants underwent standard ophthalmologic examination at baseline. Automated infrared pupillometry were performed at baseline and month 1.ResultsThe mean pupillary measurements (mm) for Group 1 (in the order photopic, mesopic, and scotopic conditions) were 2.88±0.34, 3.38±0.40, and 3.95±0.38, and changed to 3.64±0.42, 4.18±0.42, and 4.58±0.48, respectively. There was significant increase in pupil size at month 1 (P<0.001, P<0.001, and P<0.00, respectively). For Group 2, they were 2.90±0.38, 3.43±0.36, and 3.90±0.40, and changed to 3.18±0.42, 3.74±0.36, and 4.10±0.38, respectively. There was significant increase in pupil size at month 1 (P=0.018, P=0.014, and P=0.014, respectively). The pupil size increased significantly in both groups in all illumination conditions.ConclusıonWe have demonstrated via automated infrared pupillary measurements that PRP may significantly increase pupil size whether it is performed with conventional laser or PASCAL laser.

Pan-retinal photocoagulation and other forms of laser treatment and drug therapies for non-proliferative diabetic retinopathy: systematic review and economic evaluation

BACKGROUND

Diabetic retinopathy is an important cause of visual loss. Laser photocoagulation preserves vision in diabetic retinopathy but is currently used at the stage of proliferative diabetic retinopathy (PDR).

OBJECTIVES

The primary aim was to assess the clinical effectiveness and cost-effectiveness of pan-retinal photocoagulation (PRP) given at the non-proliferative stage of diabetic retinopathy (NPDR) compared with waiting until the high-risk PDR (HR-PDR) stage was reached. There have been recent advances in laser photocoagulation techniques, and in the use of laser treatments combined with anti-vascular endothelial growth factor (VEGF) drugs or injected steroids. Our secondary questions were: (1) If PRP were to be used in NPDR, which form of laser treatment should be used? and (2) Is adjuvant therapy with intravitreal drugs clinically effective and cost-effective in PRP?

ELIGIBILITY CRITERIA

Randomised controlled trials (RCTs) for efficacy but other designs also used.

DATA SOURCES

MEDLINE and EMBASE to February 2014, Web of Science.

REVIEW METHODS

Systematic review and economic modelling.

RESULTS

The Early Treatment Diabetic Retinopathy Study (ETDRS), published in 1991, was the only trial designed to determine the best time to initiate PRP. It randomised one eye of 3711 patients with mild-to-severe NPDR or early PDR to early photocoagulation, and the other to deferral of PRP until HR-PDR developed. The risk of severe visual loss after 5 years for eyes assigned to PRP for NPDR or early PDR compared with deferral of PRP was reduced by 23% (relative risk 0.77, 99% confidence interval 0.56 to 1.06). However, the ETDRS did not provide results separately for NPDR and early PDR. In economic modelling, the base case found that early PRP could be more effective and less costly than deferred PRP. Sensitivity analyses gave similar results, with early PRP continuing to dominate or having low incremental cost-effectiveness ratio. However, there are substantial uncertainties. For our secondary aims we found 12 trials of lasers in DR, with 982 patients in total, ranging from 40 to 150. Most were in PDR but five included some patients with severe NPDR. Three compared multi-spot pattern lasers against argon laser. RCTs comparing laser applied in a lighter manner (less-intensive burns) with conventional methods (more intense burns) reported little difference in efficacy but fewer adverse effects. One RCT suggested that selective laser treatment targeting only ischaemic areas was effective. Observational studies showed that the most important adverse effect of PRP was macular oedema (MO), which can cause visual impairment, usually temporary. Ten trials of laser and anti-VEGF or steroid drug combinations were consistent in reporting a reduction in risk of PRP-induced MO.

LIMITATION

The current evidence is insufficient to recommend PRP for severe NPDR.

CONCLUSIONS

There is, as yet, no convincing evidence that modern laser systems are more effective than the argon laser used in ETDRS, but they appear to have fewer adverse effects. We recommend a trial of PRP for severe NPDR and early PDR compared with deferring PRP till the HR-PDR stage. The trial would use modern laser technologies, and investigate the value adjuvant prophylactic anti-VEGF or steroid drugs.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005408.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Efficacy of Pattern Scan Laser photocoagulation for superficial conjunctival nevi ablation

This study reports the efficacy and safety of Pattern Scan Laser (PASCAL) photocoagulation in the removal of superficial conjunctival nevi. Superficial conjunctival nevi were removed from 10 eyes of 10 patients using PASCAL. The laser spots were 200 μm in size, and the power delivered ranged from 250 to 300 mW. The duration of the laser pulse was kept at the minimum needed for adequate lesion removal. The duration of the laser pulse administered to the patients varied from 100 to 200 ms. Complete removal of the conjunctival nevus was observed in all the patients after PASCAL photocoagulation. Six months after treatment, complete re-epithelialization of the overlying conjunctiva was noted. No signs of recurrence or scarring were found in any of the patients during the follow-up period. Pure thermal denaturation is the main mechanism of PASCAL photocoagulation for removal of superficial conjunctival nevi. PASCAL can be considered as an alternative to conventional argon laser treatment or surgery.

Side-effects and complications of laser treatment in diabetic retinal disease

Laser treatment for diabetic retinopathy was the first intraocular treatment to provide a highly effective means for preventing visual loss in patients with diabetes. Although inherently destructive, laser treatment is remarkably effective in preventing visual loss and preserving vision long-term. This review will describe briefly the current techniques and discuss in detail the reported side-effects and potential complications of laser treatment of diabetic retinal disease.

Changes in Central Macular Thickness following Single Session Multispot Panretinal Photocoagulation

Purpose. To determine changes in central subfield (CSF) macular thickness and best corrected visual acuity (BCVA) following single session, multispot panretinal photocoagulation (PRP). Methods. Forty eyes of 33 patients with newly diagnosed proliferative diabetic retinopathy were treated with single session, 20-millisecond, multispot PRP. Changes in central macular thickness and BCVA at 4- and 12-week follow-up were compared to baseline measurements. Results. Each eye received a mean (SD) of 2,750 (686.7) laser spots. At 4-week follow-up, there was a statistically significant 24.0 μm increase in mean CSF thickness (P = 0.001), with a 17.4 μm increase from baseline at 12-week follow-up (P = 0.002). Mean logMAR BCVA increased by 0.05 logMAR units (P = 0.03) at 4-week follow-up. At 12-week follow-up, BCVA had almost returned to normal with only an increase of 0.02 logMAR units compared to baseline (P = 0.39). Macular edema occurred in 2 eyes (5%) at 12-week follow-up. Conclusions. Macular thickening occurs following single session, 20-millisecond, multispot PRP, with a corresponding, mild change in BCVA. However, the incidence of macular edema appears to be low in these patients. Single session, 20-millisecond, multispot PRP appears to be a safe treatment for patients with proliferative diabetic retinopathy.

Laser photocoagulation for proliferative diabetic retinopathy

BACKGROUND

Diabetic retinopathy is a complication of diabetes in which high blood sugar levels damage the blood vessels in the retina. Sometimes new blood vessels grow in the retina, and these can have harmful effects; this is known as proliferative diabetic retinopathy. Laser photocoagulation is an intervention that is commonly used to treat diabetic retinopathy, in which light energy is applied to the retina with the aim of stopping the growth and development of new blood vessels, and thereby preserving vision.

OBJECTIVES

To assess the effects of laser photocoagulation for diabetic retinopathy compared to no treatment or deferred treatment.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 5), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to June 2014), EMBASE (January 1980 to June 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 3 June 2014.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) where people (or eyes) with diabetic retinopathy were randomly allocated to laser photocoagulation or no treatment or deferred treatment. We excluded trials of lasers that are no longer in routine use. Our primary outcome was the proportion of people who lost 15 or more letters (3 lines) of best-corrected visual acuity (BCVA) as measured on a logMAR chart at 12 months. We also looked at longer-term follow-up of the primary outcome at two to five years. Secondary outcomes included mean best corrected distance visual acuity, severe visual loss, mean near visual acuity, progression of diabetic retinopathy, quality of life, pain, loss of driving licence, vitreous haemorrhage and retinal detachment.

DATA COLLECTION AND ANALYSIS

We used standard methods as expected by the Cochrane Collaboration. Two review authors selected studies and extracted data.

MAIN RESULTS

We identified a large number of trials of laser photocoagulation of diabetic retinopathy (n = 83) but only five of these studies were eligible for inclusion in the review, i.e. they compared laser photocoagulation with currently available lasers to no (or deferred) treatment. Three studies were conducted in the USA, one study in the UK and one study in Japan. A total of 4786 people (9503 eyes) were included in these studies. The majority of participants in four of these trials were people with proliferative diabetic retinopathy; one trial recruited mainly people with non-proliferative retinopathy. Four of the studies evaluated panretinal photocoagulation with argon laser and one study investigated selective photocoagulation of non-perfusion areas. Three studies compared laser treatment to no treatment and two studies compared laser treatment to deferred laser treatment. All studies were at risk of performance bias because the treatment and control were different and no study attempted to produce a sham treatment. Three studies were considered to be at risk of attrition bias.At 12 months there was little difference between eyes that received laser photocoagulation and those allocated to no treatment (or deferred treatment), in terms of loss of 15 or more letters of visual acuity (risk ratio (RR) 0.99, 95% confidence interval (CI) 0.89 to 1.11; 8926 eyes; 2 RCTs, low quality evidence). Longer term follow-up did not show a consistent pattern, but one study found a 20% reduction in risk of loss of 15 or more letters of visual acuity at five years with laser treatment. Treatment with laser reduced the risk of severe visual loss by over 50% at 12 months (RR 0.46, 95% CI 0.24 to 0.86; 9276 eyes; 4 RCTs, moderate quality evidence). There was a beneficial effect on progression of diabetic retinopathy with treated eyes experiencing a 50% reduction in risk of progression of diabetic retinopathy (RR 0.49, 95% CI 0.37 to 0.64; 8331 eyes; 4 RCTs, low quality evidence) and a similar reduction in risk of vitreous haemorrhage (RR 0.56, 95% CI 0.37 to 0.85; 224 eyes; 2 RCTs, low quality evidence).None of the studies reported near visual acuity or patient-relevant outcomes such as quality of life, pain, loss of driving licence or adverse effects such as retinal detachment.We did not plan any subgroup analyses, but there was a difference in baseline risk in participants with non-proliferative retinopathy compared to those with proliferative retinopathy. With the small number of included studies we could not do a formal subgroup analysis comparing effect in proliferative and non-proliferative retinopathy.

AUTHORS' CONCLUSIONS

This review provides evidence that laser photocoagulation is beneficial in treating proliferative diabetic retinopathy. We judged the evidence to be moderate or low, depending on the outcome. This is partly related to reporting of trials conducted many years ago, after which panretinal photocoagulation has become the mainstay of treatment of proliferative diabetic retinopathy.Future Cochrane Reviews on variations in the laser treatment protocol are planned. Future research on laser photocoagulation should investigate the combination of laser photocoagulation with newer treatments such as anti-vascular endothelial growth factors (anti-VEGFs).

Systematic review of various laser intervention strategies for proliferative diabetic retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes. DR obstructs blood supply to the retina and has serious and long-lasting detrimental effects on quality of life. Panretinal photocoagulation, a laser surgical intervention, is advocated for early treatment of DR to prevent visual loss; however, results from studies reporting its efficacy vary markedly. In this review, we systematically conducted a database search of randomized controlled trials that investigated the safety and efficacy of different types of laser interventions, alone or in combination with adjunct intravitreal steroid utilization, in patients with DR. Data from 14 studies demonstrated that panretinal photocoagulation can be a safe and effective option for reducing visual loss and blindness in patients with DR.