A meta-analysis to study the effect of pan retinal photocoagulation on retinal nerve fiber layer thickness in diabetic retinopathy patients

Background. Diabetic retinopathy is a microvascular disease, it is associated with changes in peripapillary retinal nerve fiber layer thickness, these changes being more pronounced in PDR (Proliferative diabetic retinopathy) patients undergoing laser photocoagulation. Objective. To assess changes in peripapillary retinal nerve fiber layer thickness in proliferative diabetic retinopathy patients using optical coherence tomogram (OCT). Methods. The database search was conducted in June 2018 and continued until October 2018. The search engines used included Pubmed, Medline, OVID and Google Scholar. A meta-analysis of weighted mean difference and standard deviation was conducted. Results. A total of 10 studies containing 377 eyes of PDR patients were selected. The analysis of the included studies revealed no significant effect of PRP on average retinal nerve fiber layer thickness (0.249, 95% CI: -0.985 to 1.483) using OCT. Conclusion. Hence, to conclude, our meta-analysis revealed that there was no significant effect of PRP on RNFL thickness and the impact of PRP could vary. Measurement of peripapillary RNFL thickness may yield erroneous and unpredictable results in this subgroup of patients, further confounding the evaluation of nerve fiber layer damage and its progression.

Longitudinal analysis of subfoveal choroidal thickness after panretinal laser photocoagulation in diabetic retinopathy using swept-source optical coherence tomography

Purpose: To describe the central three-dimensional (3D) thickness profile of the macula (CMT) and the subfoveal choroidal region (SFCT) in diabetic retinopathy (DR) following panretinal laser photocoagulation (PRP) using swept-source optical coherence tomography (SS-OCT). Methods: A prospective observational study including 17 eyes with proliferative DR (PDR) and 27 eyes with severe nonproliferative DR (sNPDR)] for whom PRP was done. All subjects received SS-OCT imaging before and 3 months after PRP (POM#3). SFCT and CMT changes were analysed at both visits. Intraclass Correlation Coefficients (ICC) and Coefficients of Variation (COV) were used to test the accuracy of thickness data. Results: SFCT has thinned from 233 ± 54 µm before PRP treatment to 216 ± 51 µm 3 months later (p < 0.001). Likewise, CMT declined at POM#3 as compared to pre-PRP status (p<0.001). SFCT was thinner in PDR before and at POM#3 (p<0.05) than sNPDR; whereas, no significant difference was observed in CMT between both groups in the two visits. No significant changes were found between groups in SFCT and CMT at POM#3. Regarding reliability, ICCSFCT=0.98 and ICCCMT=0.99. The COVs for CMT and SFCT were 5.03% and 5.91%, respectively. Conclusion: The mean SFCT and CMT decreased 3 months after PRP. We also reported reliability of SFCT measurements in DR using SS-OCT. Abbreviations: SS = Swept-Source, TD = time domain, SD = spectral domain, FD = Fourier-domain, 3D = three-dimensional, 2D = two-dimensional.

Vascular endothelial growth factor inhibition and proliferative diabetic retinopathy, a changing treatment paradigm?

Prior to the development of panretinal photocoagulation (PRP) in the 1970s, proliferative diabetic retinopathy (PDR) was the most common cause of blindness in diabetic patients. The diabetic retinopathy study demonstrated that PRP could decrease severe visual loss from PDR by 50%. Since then and for the past four decades, PRP has been the treatment of choice for eyes with PDR. In the past decade, vascular endothelial growth factor (VEGF) inhibition has become the treatment of choice for diabetic macular edema (DME). When treated intensively with anti-VEGF drugs, about one-third of eyes with DME experience an improvement in their diabetic retinopathy severity scale. Randomized clinical trials comparing ranibizumab to PRP and aflibercept to PRP have shown that VEGF inhibitors cause regression of intraocular neovascularization but need to be given on a fairly regular basis. Despite these promising results, concerns about treatment adherence have surfaced. Patients with PDR that are treated solely with anti-VEGF drugs and somehow interrupt their treatment are at a high risk of developing irreversible blindness. Combination treatment of PRP plus an anti-VEGF drug may be the treatment of choice for PDR.

Reading deficits in diabetic patients treated with panretinal photocoagulation and good visual acuity

PURPOSE

Patients with proliferative diabetic retinopathy (PDR) treated with panretinal photocoagulation (PRP) can have abnormal visual functioning that may be missed by Snellen visual acuity alone. We investigated reading deficits in patients treated with PRP for PDR using the Minnesota reading (MNREAD) test.

METHODS

Thirty patients treated with PRP and 15 controls underwent best-corrected visual acuity (BCVA), the MNREAD, frequency doubling perimetry (FDP), and fundus photography. Panretinal photocoagulation (PRP)-treated subjects were compared to controls on MNREAD results by two-sample t-tests and Wilcoxon tests and Pearson correlations were used to assess the association between performance on MNREAD and other central visual function tests within PRP subjects.

RESULTS

Panretinal photocoagulation (PRP)-treated patients had reduced MNREAD acuity (p < 0.0001) and increased critical print size (p = 0.01) compared to controls but not a significantly reduced maximum reading speed (p = 0.06). Logmar MNREAD acuity was strongly positive correlated with logMAR BCVA (r = 0.58, p = 0.0098) and strongly negatively correlated with FDP foveal threshold (r = -0.63, p = 0.0030). Maximum reading speed was positively correlated with FDP foveal threshold (r = 0.57, p = 0.0143) and FDP mean deviation (r = 0.51, p = 0.0432). Visual acuity did not correlate with the sensitivities on the FDP.

CONCLUSION

The MNREAD test reveals that PRP reduces reading ability and other aspects of macular function, and thus provides new understanding of how vision-related quality of life is impaired. These findings may lead to improved means to evaluate and enhance vision following treatment for PDR.

Long term effect of panretinal photocoagulation on retinal nerve fiber layer parameters in patients with proliferative diabetic retinopathy

PURPOSE:

This study aimed to evaluate the long-term effect of panretinal photocoagulation (PRP) on the retinal nerve fiber layer (RNFL) in patients with proliferative diabetic retinopathy (PDR).

METHODS:

This was a prospective longitudinal cohort study examining 42 eyes of 42 patients with PDR undergoing PRP. Peripapillary RNFL thickness (RNFLT) was measured using spectral-domain optical coherence tomography at baseline, 1 year, and 3 years following PRP.

RESULTS:

The mean “average RNFLT” was 89.88 ± 14.26 μm at baseline, 85.75 ± 11.36 μm at 1-year follow-up, and 83.33 ± 11.96 μm at 3-year follow-up. There was a statistically significant difference in the average RNFL thickness at baseline and 1 year and 3 years after PRP. At 1-year follow-up, superior, inferior, and nasal RNFL measurements reduced significantly from baseline (P < 0.01). The reduction in RNFL remained statistically significant for superior and inferior quadrants 3 years after PRP.

CONCLUSION:

PRP causes a reduction in RNFL thickness until 3 years after the procedure. Caution should be exercised while interpreting peripapillary RNFL thickness scans in patients who have undergone PRP for diabetic retinopathy.

Central retinal thickness following panretinal photocoagulation using a multispot semi-automated pattern-scanning laser to treat ischaemic diabetic retinopathy: Treatment in one session compared with four monthly sessions

PURPOSE

To compare central retinal thickness (CRT) after panretinal photocoagulation (PRP) with a multispot semi-automated PAttern-SCAnning Laser (PASCAL) in one session (SS-PRP) versus four monthly sessions (MS-PRP) in diabetic retinopathy.

METHODS

Multicentre, prospective, randomized, single-blinded, controlled trial evaluating the noninferiority of SS-PRP versus MS-PRP for CRT measured with macular spectral-domain optical coherence tomography (SD-OCT), with a 9-month follow-up in patients presenting severe nonproliferative diabetic retinopathy (DR) or mild proliferative DR without macular oedema (ME) at baseline.

RESULTS

Ninety-seven eyes of 97 participants with a mean age of 57.0 ± 14.2 years were included. The mean change of CRT from baseline to 9 months was not statistically different in SS-PRP or in MS-PRP: +16.9 ± 28.3 μm versus +24.7 ± 31.8 μm, respectively (p = 0.224). The variation in mean best-corrected visual acuity (BCVA) from baseline to 9 months was similar in both groups: -1.1 ± 6.5 letters versus -0.6 ± 6.2 letters (p = 0.684). The number of patients with stabilization of DR was not statistically different between the two groups. No severe complication was recorded in either group.

CONCLUSION

This study showed the noninferiority of PRP performed in one session versus four monthly sessions with a PASCAL concerning central retinal thickness for treating mild proliferative or severe nonproliferative DR without ME at baseline.

Intravitreal Ranibizumab With Panretinal Photocoagulation Followed by Trabeculectomy Versus Visco-Trabeculotomy in Management of Neovascular Glaucoma

PURPOSE

The aim of the current study was to compare visco-trabeculotomy (VT) with standard trabeculectomy with mitomycin C (Trab-MMC) in the treatment of quiescent neovascular glaucoma (NVG).

METHODS

The study was conducted on 51 eyes of 51 patients presenting with NVG and treated at an Ophthalmic Center in Egypt between March 2014 and April 2017. All study eyes were subjected to a standard protocol of intravitreal injection of ranibizumab followed by panretinal photocoagulation. Eyes were then randomized to either VT or Trab-MMC. Study eyes were followed up for at least 18 months. Success was defined as an intraocular pressure of ≤21 mm Hg and without vision-threatening complications. Complications were noted.

RESULTS

The mean ± SD (range, median) age of the study patients was 54.1 ± 6.4 (40-67, 54.5) and 52.4 ± 8.8 (38-66, 53) years in the VT (26 eyes) and Trab-MMC (25 eyes) groups, respectively (P = 0.45). The mean ± SD (range, median) intraocular pressure (IOP) of the study eyes was 45.19 ± 2.97 (39-52, 45.5) and 45.64 ± 3.56 (3-53, 45) mm Hg on maximal medical therapy in the VT and Trab-MMC groups, respectively (P = 0.61). At 18 months' follow-up, the mean ± SD (range, median) IOP of the study eyes was 18.19 ± 2.0 (16-23, 17) and 19.92 ± 2.6 (18-26, 19) mm Hg in the VT and Trab-MMC groups, respectively (P = 0.004). There was no difference in postoperative antiglaucoma medication between the 2 groups (P = 0.62). Complications included hyphema and Descemet split in the VT group and an IOP spike in the Trab-MMC group. Success rates were 84.6% and 80% in the VT and Trab-MMC groups, respectively (P = 0.726).

CONCLUSIONS

Both VT and Trab-MMC groups are effective in reducing the IOP in cases of NVG after control of neovascularization with anti-vascular endothelial growth factor and pan retinal photocoagulation.

Evaluation of blood flow on optic nerve head after pattern scan and conventional laser panretinal photocoagulation

To evaluate the changes in the blood flow on retina and the optic nerve head (ONH) after conventional laser treatment and to compare it to that after patterned scanning laser (PASCAL) treatment in patients with severe nonproliferative diabetic retinopathy (S-NPDR).In this prospective, cross-sectional study, the blood flow on retina and the ONH was assessed by laser speckle flowgraphy using the mean blur rate (MBR) in 39 eyes with S-NPDR before, 1, 4, 8, 12 weeks after panretinal photocoagulation (PRP). Of 39 eyes, 17eyes with 17 patients treated by conventional laser and 22 eyes with 22 patients treated by PASCAL.The mean age was 55.5 ± 11.5 years in the conventional laser group, 55.6 ± 11.8 years in the PASCAL group. The MBR-vessel, which can be dominantly expressed as retinal blood flow, was significantly reduced after PRP treated by conventional laser (P < .001), but did not change after PRP treated by PASCAL. The ratio of MBR-vessel to the baseline was significantly lower in the conventional laser group only at Week 1 (P = .045). The MBR-tissue, which can be dominantly expressed as the ONH blood flow, did not significantly change after PRP in the both group. The multiple stepwise regression analysis revealed that the laser burns was an independent factor significantly correlated with the ratio of MBR-vessel at Week 1 to the baseline (β = -0.550, P = .012).The retinal blood flow was significantly reduced during the 12 weeks only after completion of PRP by conventional laser treatment. Our results indicate that short pulse on PRP treatment performed by the PASCAL would not significantly reduce the retinal blood flow.

Efficacy of panretinal laser in ischemic central retinal vein occlusion: A systematic review

The aim of the present systematic review was to assess the efficacy of laser therapy for ischemic central retinal vein occlusion (CRVO). Relevant studies were retrieved by searching the PubMed, Embase, Chinese Biomedical Literature Database and, Chinese Science and Technology Periodicals databases using a combination of key words, including 'central retinal vein obstruction', 'CRVO', 'laser' and 'panretinal photocoagulation'. The titles, abstracts and full texts were screened by two independent reviewers and studies were selected according to specific inclusion criteria. Data were extracted and the quality of each study was graded using the Grading of Recommendations, Assessment, Development and Evaluation or Methodological Index for Non-Randomized Studies (MINORS) criteria. A total of 1,187 abstracts were retrieved, and finally, 11 clinical studies were selected, including 534 cases of CRVO. Of these, 8 studies compared the efficacy of laser therapy with other treatments for CRVO, two studies compared the efficacy of laser therapy and drug treatment for CRVO and one study compared the efficacy of early laser therapy with standard laser therapy (regular examinations and laser therapy performed as soon as neovascularization was identified) for CRVO. Among them, the results of five studies demonstrated that panretinal photocoagulation (PRP) for the prevention of iris neovascularization and neovascular glaucoma is inefficient regarding the improvement of visual acuity. A total of 10 studies indicated that laser therapy achieved better outcomes in neovascularization of the retina, optic disc neovascularization and iris neovascularization, neovascular glaucoma, vitreous hemorrhage, changes in the visual field, macular edema, macular thickness and intraocular pressure. Of note, it was indicated that laser photocoagulation prevents the severe vascular complications of CRVO. In addition, in the eyes of patients receiving PRP for the treatment of ischemic CRVO, significant reductions in corneal sub-basal nerve plexus parameters and average peripapillary retinal nerve fiber layer thickness were observed. Furthermore, laser photocoagulation was able to increase retinal blood flow in eyes with ischemic CRVO.

Effect of panretinal photocoagulation on the peripapillary retinal nerve fiber layer in diabetic retinopathy patients

OBJECTIVES

To determine the effect of panretinal photocoagulation (PRP) on the peripapillary retinal nerve fiber layer (RNFL) in nonglaucomatous patients with proliferative diabetic retinopathy (PDR).

METHODS

This is a prospective, single center, observational study. Thirty-eight eyes of 26 diabetic patients underwent PRP for proliferative diabetic retinopathy. Peripapillary RNFL thickness was measured using scanning laser polarimetry (SLP) with variable corneal compensation (GDx VCC; by Carl Zeiss Meditec, Dublin, CA) and spectral-domain optical coherence tomography (OCT) (Heidelberg Spectralis, Carlsbad, USA) at baseline and 12 months after PRP was performed.

RESULTS

Thirty-eight eyes of 26 patients (15 female) with a mean age of 53.7 years (range 26 to 74 years) were recruited. No significant difference was found among all RNFL thickness parameters tested by GDx VCC software (p=0.952, 0.464 and 0.541 for temporal-superior-nasal-inferior-temporal (TSNIT) average, superior average, inferior average, respectively). The nerve fiber indicator (NFI) had a nonsignificant increase (p=0.354). The OCT results showed that the average RNFL thickness (360° measurement) decreased nonsignificantly from 97.2 mm to 96.0 mm at 1 year post-PRP (p=0.469). There was no significant difference when separately analyzing all the peripapillary sectors (nasal superior, temporal superior, temporal, temporal inferior, nasal inferior and nasal thickness).

CONCLUSION

Our results suggest that PRP, as performed in our study, does not cause significant changes in peripapillary RNFL in diabetic PDR patients after one year of follow-up.

Sequence effect in the treatment of proliferative diabetic retinopathy with intravitreal ranibizumab and panretinal photocoagulation

PURPOSE

To compare the outcome of the sequence in the two treatments (intravitreal ranibizumab and panretinal photocoagulation) in high-risk proliferative diabetic retinopathy.

METHODS

This retrospective study included 35 patients with newly diagnosed high-risk proliferative diabetic retinopathy in 43 eyes; 18 (22 eyes) received intravitreal ranibizumab before panretinal photocoagulation (intravitreal ranibizumab+ group), while the other 17 (21 eyes) received panretinal photocoagulation before intravitreal ranibizumab (panretinal photocoagulation+ group). Each subject received three intravitreal ranibizumabs that were interleaved with three panretinal photocoagulations. The first treatment (either intravitreal ranibizumab or panretinal photocoagulation) was done 1 week before the second one. The interval between intravitreal ranibizumabs was 4 weeks, panretinal photocoagulation was 2 weeks. The power and pulse duration were determined based upon the status of each retinal spot before each panretinal photocoagulation. The retinal non-perfusion region was measured with fundus fluorescein angiography before and 1 month after the final treatment. The central macular thickness was measured with optical coherence tomography within 1 week before the first treatment, before each panretinal photocoagulation, and 1 month after the final intravitreal ranibizumab.

RESULTS

The panretinal photocoagulation energy required for effective treatment was lower in intravitreal ranibizumab+ group in the first and second sessions and in total energy (p < 0.05). Central macular thickness reduction before the second panretinal photocoagulation session was significant in the intravitreal ranibizumab+ group (p < 0.05).

CONCLUSION

The sequence used in intravitreal ranibizumab+ group showed clear advantages over that in panretinal photocoagulation+ group in the treatment of proliferative diabetic retinopathy, not only in the use of lower energy for panretinal photocoagulation but also in the more rapid regression of neovascularization and less need of additional treatment.

Mechanistic Evaluation of Panretinal Photocoagulation Versus Aflibercept in Proliferative Diabetic Retinopathy: CLARITY Substudy

Purpose

The purpose of this study was to study the effects of panretinal photocoagulation (PRP) and intravitreal aflibercept on retinal vessel oxygen saturations, area of retinal nonperfusion, and area of neovascularization in proliferative diabetic retinopathy.

Methods

This is a prospective randomized single center study. Forty patients with proliferative diabetic retinopathy were randomized to PRP or intravitreal aflibercept treatment for 52 weeks. Retinal oximetry and ultra-widefield angiography were performed at baseline and week 52. Ultra-widefield color fundus imaging was performed at baseline, week 12, and week 52. The outcomes were retinal arterio-venous oximetry differences (AVD), area of retinal nonperfusion, and area of neovascularization in disc areas (DA).

Results

The AVD in the PRP group increased from 36.7% at baseline to 39.7%, whereas it decreased from 33.4% to 32.5% in the aflibercept group. The difference in AVD between groups at week 52 was 4.0% (95% confidence interval, -0.08, 8.8; P = 0.10). The baseline mean area of retinal nonperfusion of 125.1 DA and 131.2 DA in the PRP and aflibercept groups increased to 156.1 DA and 158.4 DA, respectively, at week 52 (P = 0.46). The median baseline area of neovascularization decreased from 0.98 DA to 0.68 DA in the PRP group and from 0.70 DA to 0 DA in the aflibercept group at week 12 (P = 0.019). At week 52, this measured 0.24 DA in the PRP group and 0 DA in the aflibercept group (P = 0.45).

Conclusions

Intravitreal aflibercept achieved an earlier and complete regression of neovascularization in proliferative diabetic retinopathy compared with PRP. There were no significant differences in global change in intravascular oxygen saturation or areas of retinal nonperfusion between the two groups by 52 weeks.

Temporal changes in retinal vascular parameters associated with successful panretinal photocoagulation in proliferative diabetic retinopathy: A prospective clinical interventional study

Purpose

We aimed to investigate changes in retinal vascular geometry over time after panretinal photocoagulation (PRP) in patients with proliferative diabetic retinopathy (PDR).

Methods

Thirty‐seven eyes with PDR were included. Wide‐field fluorescein angiography (Optomap, Optos PLC., Dunfermline, Scotland, UK) was used to diagnose PDR at baseline and to assess activity at follow‐up month three and six. At each time‐point, a trained grader measured retinal vessel geometry on optic disc (OD) centred images using semiautomated software (SIVA, Singapore I Vessel Assessment, National University of Singapore, Singapore) according to a standardized protocol.

Results

At baseline, the mean age and duration of diabetes were 52.8 and 22.3 years, and 65% were male. Mean HbA1c was 69.9 mmol/mol, and blood pressure was 155/84 mmHg. Of the 37 eyes with PDR, eight (22%) eyes had progression at month three and 13 (35%) progressed over six months. Baseline characteristics, including age, sex, duration of diabetes, HbA1c, blood pressure, vessel geometric variables and total amount of laser energy delivered did not differ by progression status. However, compared to patients with progression of PDR, patients with favourable treatment outcome had alterations in the retinal arteriolar structures from baseline to month six (calibre, 154.3 μm versus 159.5 μm, p = 0.04, tortuosity 1.12 versus 1.10, p = 0.04) and in venular structures from baseline to month three (fractal dimension 1.490 versus 1.499, p = 0.04, branching coefficient (BC) 1.32 versus 1.37, p = 0.01).

Conclusion

In patients with PDR, successful PRP leads to alterations in the retinal vascular structure. However, baseline retinal vascular geometry characteristics did not predict treatment outcome.

Subthreshold microsecond laser for proliferative diabetic retinopathy: a randomized pilot study

Aim

To compare the outcomes of subthreshold microsecond (STM) and continuous-wave laser (CWL) panretinal photocoagulation (PRP).

Methods

In this randomized, prospective, pilot study, 20 eyes of 10 subjects with symmetric severe non-proliferative (NPDR) or low-risk proliferative diabetic retinopathy (PDR) were included. Each eye of the subject was randomized into either CWL or STM PRP group. Patients were evaluated at baseline and at months 3, 6, and 9 with color fundus photographs and visual field tests at each visit; however, electroretinography (ERG) was conducted at baseline and at month 9. The primary outcome measure was the difference in disease progression between the groups. Secondary outcome measures included change in visual acuity, contrast visual acuity, retinal sensitivity on visual field test, and change in ERG parameters.

Results

During the 9-month follow-up, one eye of the STM group progressed to vitreous hemorrhage at the month 6 follow-up and required rescue conventional laser. The CWL group showed a drop in low-contrast visual acuity, visual field index, and scotopic b/a ratio in comparison to the STM group, although the difference was statistically insignificant (p>0.05).

Conclusion

This prospective pilot study proposes microsecond PRP is non-inferior to CWL PRP and could be an alternative to CWL PRP to avoid associated complications in cases of severe NPDR and early PDR.

Idiopathic retinal vasculitis, aneurysms, and neuroretinitis (IRVAN) syndrome: clinical perspectives

Idiopathic retinal vasculitis, aneurysms, and neuroretinitis (IRVAN) syndrome typically affects young, healthy individuals. Despite the dramatic fundus appearance seen in this syndrome, these patients are usually asymptomatic. The syndrome includes peculiar vascular abnormalities in the form of multiple aneurysmal dilatations seen along retinal arterioles and optic nerve-head arterioles, which are best appreciated on fluorescein angiography. Neuroretinitis and retinal vasculitis are seen in all patients, and manifested by staining of the optic nerve head and diffuse leakage from vessels, mainly arterioles, on fluorescein angiography. The devastating vision-threatening outcomes of this syndrome include exudative retinopathy and extensive peripheral retinal nonperfusion areas, which can eventually lead to neovascularization. This review summarizes current knowledge on the variable clinical aspects of this disease, highlighting diagnostic and treatment strategies.

Efficacy and safety of intravitreal ranibizumab with panretinal photocoagulation followed by trabeculectomy compared with Ahmed glaucoma valve implantation in neovascular glaucoma

AIM

To evaluate the efficacy and safety of intravitreal ranibizumab (IVR) with panretinal photocoagulation (PRP) followed by trabeculectomy compared with Ahmed glaucoma valve (AGV) implantation in neovascular glaucoma (NVG).

METHODS

This was a retrospective comparative study. We reviewed the cases of a total of 45 eyes from 45 NVG patients among which 23 eyes underwent AGV implantation and the other 22 underwent trabeculectomy. The causes of neovascular glaucoma included: diabetic retinopathy (25 eyes), and retinal vein occlusion (20 eyes). All patients received preoperative IVR combined with postoperative PRP. The mean best-corrected visual acuities (BCVA) were converted to the logarithms of the minimum angle of resolution (logMAR) for the statisitical analyses. Intraocular pressure (IOP), the logMAR BCVA and surgical complications were evaluated before and after surgery. The follow-up period was 12mo.

RESULTS

A total of 39 cases showed complete regression of iris neovascularization at 7d after injection, and 6 cases showed a small amount of residual iris neovascularization. The success rates were 81.8% and 82.6% at 12mo after trabeculectomy and AGV implantation, respectively. In the trabeculectomy group, the logMAR BCVA improved at the last follow-up in 14 eyes, remained stable in 6 eyes and decreased in 2 eyes. In 4 cases, slight hyphemas developed after trabeculectomy. A shallow anterior chamber developed in 2 cases and 2 vitreous hemorrhages. In the AGV group, the logMAR BCVA improved in 14 eyes, remained stable in 5 eyes and decreased in 4 eyes. Slight hyphemas developed in 3 cases, and a shallow anterior chamber in 3 cases. The mean postoperative IOP was significantly lower in both groups after surgery (F=545.468, P<0.05), and the mean postoperative logMAR BCVA was also significantly improved (F=10.964, P<0.05) with no significant difference between two groups.

CONCLUSION

It is safe and effective to treat NVG with this combined procedure, and we found similar results after IVR+AGV implantation+PRP and IVR+trabeculectomy+PRP in eyes with NVG.

Long-term Effect of Panretinal Photocoagulation on Spectral Domain Optical Coherence Tomography Measurements in Diabetic Retinopathy

PURPOSE

To evaluate the effects of panretinal photocoagulation on spectral domain optical coherence tomography measurements in diabetic retinopathy by comparing the thicknesses of the central macula, retinal nerve fiber layer, and ganglion cell layer, we used a Cirrus HD OCT® (Carl Zeiss Meditec, Dublin, CA, USA) in normal and diabetic retinopathy cohorts.

METHODS

We analyzed patients who visited our retinal clinic between May 2013 and July 2014. The patients were classified into four groups: normal (Group A), diabetes without diabetic retinopathy (Group B), severe nonproliferative or proliferative diabetic retinopathy (Group C), and at least 3 years after panretinal photocoagulation treatment (Group D). The mean thicknesses of the macula, retinal nerve fiber layer, and ganglion cell layer in each group were compared by measuring a macular cube 512 × 128 scan and an optic disc cube 200 × 200 scan twice.

RESULTS

In total, 154 patients were enrolled. The mean thickness of the central macula in groups A to D was 257.2, 256.8, 257.4, and 255.6 µm, respectively, and did not differ significantly. The mean thickness of the RNFL in group A to D was 96.8, 96.5, 97.2, and 92.8 µm, respectively, and was significantly lower in group D (decreased in the inferior, superior, and nasal sectors, but increased in the temporal). The mean thickness of the ganglion cell layer was also significantly lower in group D (A, 84.5 µm; B, 84.4 µm; C, 82.5 µm; D, 78.5 µm).

CONCLUSIONS

The mean thicknesses of the retinal nerve fiber and ganglion cell layers were decreased significantly in eyes with diabetic eye disease treated with panretinal photocoagulation compared to normal or eyes with diabetic eye disease that had not been laser-treated. Laser treatment might have altered the thickness of the inner layer of the retina, and such changes should be considered in diabetic retinopathy patients after panretinal photocoagulation treatment.

Panretinal photocoagulation versus panretinal photocoagulation plus intravitreal bevacizumab for high-risk proliferative diabetic retinopathy

AIM

To evaluate the effects of panretinal photocoagulation (PRP) compared with PRP plus intravitreal bevacizumab (IVB) in patients with high-risk proliferative diabetic retinopathy (PDR) according to the Early Treatment Diabetic Retinopathy Study criteria.

METHODS

The data were collected retrospectively from the eyes of high-risk PDR patients, which were divided into two groups. After treated with standard PRP, the eyes were randomly assigned to receive only PRP (PRP group) or PRP plus intravitreal injection of 1.25 mg of bevacizumab (PRP-Plus group). Patients underwent complete ophthalmic evaluation, including best corrected visual acuity (BCVA), intraocular pressure (IOP), and new vessel size in fluorescein angiography (FA) and optical coherence tomography for the assessment of central subfield macular thickness (CSMT) at baseline and at weeks 12 (±2), 16 (±2), 24 (±2) and 48 (±2). Main outcome measures also included vitreous clear-up time and neovascularization on the disc (NVD) regression time. Adverse events associated with intravitreal injection were investigated.

RESULTS

Thirty consecutive patients (n=36 eyes) completed the 48-week follow-up. There was no significant difference between the PRP and PRP-Plus groups with respect to age, gender, type or duration of diabetes, area of fluorescein leakage from active neovascularizations (NVs), BCVA or CSMT at baseline. The mean vitreous clear-up time was 12.1±3.4wk after PRP and 8.4±3.5wk after PRP combined with IVB. The mean time interval from treatment to complete NVD regression on FA examination was 15.2±3.5wk in PRP group and 12.5±3.1wk in PRP-Plus group. No significant difference in CSMT was observed between the groups throughout the study period. However, the total area of actively leaking NVs was significantly reduced in the PRP-Plus group compared with the PRP group (P<0.05). Patients received an average of 1.3 injections (range: 1-2). Ten eyes (27.8%) underwent 2 injections. Two eyes had ocular complication of PDR progression to dense vitreous hemorrhage (VH). No major adverse events were identified.

CONCLUSION

The adjunctive use of IVB with PRP is associated with a greater reduction in the area of active leaking NVs than PRP alone in patients with high-risk PDR. Short-term results suggest combined IVB and PRP achieved rapid clearance of VH and regression of retinal NV in the treatment of high-risk PDR. Further studies are needed to determine the effect of repeated intravitreal bevacizumab injections and the proper number of bevacizumab injections as an adjuvant.

Evidence-Based Treatment of Diabetic Retinopathy

Diabetic retinopathy (DR) is the most frequent microvascular complication from diabetes and requires annual screening and at least annual follow-up. A systemic approach to optimize blood glucose and blood pressure may halt progression to severe stages of DR and obviate the need for ocular treatment. Although there is evidence of benefit from fenofibrate or intravitreous antiVEGF treatment for eyes with nonproliferative DR (NPDR), these therapies are not standard care for NPDR at this time. Some patients with severe NPDR, especially those with type 2 diabetes, benefit from early panretinal photocoagulation (PRP). Once DR progresses to proliferative DR (PDR), treatment is often necessary to prevent visual loss. PRP remains mainstay treatment for PDR with high-risk characteristics. However, intravitreous antiVEGF injections appear to be a safe and effective treatment alternative for PDR through at least two years. Vitreoretinal surgery is indicated for PDR cases with non-clearing vitreous hemorrhage and/or tractional retinal detachment.

Changes in the Macular Ganglion Cell Complex Thickness and Central Macular Thickness after Argon Laser Panretinal Photocoagulation

PURPOSE

To evaluate the changes in the macular ganglion cell complex (GCC) thickness and central macular thickness (CMT) as measured by spectral domain optical coherence tomography (OCT) post-argon laser panretinal photocoagulation (PRP).

METHODS

The medical records of 25 patients with proliferative diabetic retinopathy (PDR) who underwent PRP, 29 patients with non-proliferative diabetic retinopathy (NPDR), and 29 patients with diabetes but without diabetic retinopathy (DR) were analyzed. The patients who received PRP were followed up for one year. The follow-up measurements were evaluated at baseline, and months 1, 6, and 12 post-argon laser PRP. The baseline values of CMT and GCC thickness were compared among the groups to assess changes with PRP therapy.

RESULTS

The CMT gradually increased in months 1 and 6 and then decreased; however, it was significantly higher than the baseline value at month 12 in the PDR group post-PRP. The GCC thickness also increased at months 1 and 6 in almost all segments of the macula, but at month 12 decreased to the baseline value. There was no correlation between the increasing thickness of the macula and change in the GCC thickness post-PRP period in the PDR group. In addition, no significant correlation was detected between the GCC thickness and best-corrected visual acuity during all follow-up visits.

CONCLUSIONS

GCC thickness increased significantly until month 6 compared with baseline values in most of the macular segments post-PRP in the PDR group. The GCC thickness at month 12 was not different from the baseline thickness in any of the macular segments.

Diabetic Macular Edema: From Old Concepts to New Therapeutic Avenues

Diabetic macular edema (DME) is a significant cause of blindness in the working population and is currently challenging to treat. Current interventions include focal laser or intravitreal injections. This article outlines a new treatment protocol based on the theory that peripheral ischemia is the precursor to angiogenesis, which will ultimately gather its momentum at the fovea. Extreme peripheral light laser panretinal photocoagulation (PRP) back to the equator reduces excessive production of the vascular endothelial growth factor (VEGF) in the eye. This decreases VEGF-induced DME and provides long-term protection against the development of neovascularization. Initial exacerbation of DME often accompanies PRP. Therefore, injections of anti-VEGF agents (with or without dexamethasone implants) initially can forestall worsening of DME and prevent loss of vision. However, on the other hand, applying peripheral PRP and intraocular injections can induce posterior vitreous detachment (PVD). This could help release vitreomacular adhesions (VMA) and vitreomacular traction (VMT), thereby decreasing DME severity and improving the response to intravitreal injections. In the current approach, peripheral retinal photocoagulation should stop the drive for VEGF release; moreover, laser ablation should produce secondary, accidental, and beneficial PVD. This approach precludes focal laser therapy and paves the path for prolonged intervals between anti-VEGF therapy.

Retinal Nerve Fiber Layer Alterations After Photocoagulation: A Prospective Spectral-Domain OCT Study

PURPOSE

To evaluate the effect of panretinal photocoagulation (PRP) on retinal nerve fiber layer thickness (RNFLT) in treatment-naive patients with proliferative diabetic retinopathy (PDR).

METHODS

Fifty eight previously untreated eyes of 30 patients with PDR who underwent PRP treatment were enrolled prospectively. All patients had at least six months of follow-up. Detailed ophthalmologic examinations including macular thickness and RNFLT assessments with spectral-domain type optic coherence tomography were performed at baseline as well as the third and sixth posttreatment months. Initial RNFLT and macular thickness of laser administered patients were compared with two separate control groups that were consisted of either nondiabetic patients or diabetics without PDR.

RESULTS

The mean age of study patients was 52.4±7.1 years (Range, 32-66 years) and 16 of them (53.3%) were female. At the sixth post-PRP month, visual stabilization or improvement was achieved in 54 eyes (93.1%). No significant difference was demonstrated in initial RNFLT measurements between the study patients and two control groups (p=0.478). Mean RNFLT was measured as 108.5±17.5µm, 115.8±17.6µm, and 103.0±16.4µm at baseline, third and sixth months of the follow-up, respectively. Although RNFLT increase noted at the third post-laser month was statistically significant compared to its baseline values (p<0.001), there was a significant reduction in RNFLT at the sixth post-laser month compared to its baseline values (p<0.001).

CONCLUSION

RNFLT increase in the third month of follow-up may be related to ensuing axonal edema. Significant RNLFT decrease at the sixth month of follow-up may be attributed to axonal loss secondary to the laser treatment.

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.

Prognostic value of multifocal electroretinography and optical coherence tomography in eyes undergoing panretinal photocoagulation for diabetic retinopathy

PURPOSE

To investigate the prognostic utility on visual acuity of multifocal electroretinography (mfERG) and optical coherence tomography (OCT) in diabetic eyes receiving panretinal photocoagulation (PRP).

METHODS

Patients with severe nonproliferative diabetic retinopathy (NPDR) or early proliferative diabetic retinopathy (PDR) who needed PRP were included in this study. The mfERG and OCT data were recorded before PRP, and the final best-corrected visual acuity (BCVA) was recorded at 6 months after PRP. The correlation between pre-PRP data and post-PRP BCVA was analyzed using Pearson's correlation analysis and multivariate linear regression analysis.

RESULTS

Among the 42 eyes included, 31 eyes (73.8%) had improvement or remained stable in visual acuity, and 11 eyes (26.2%) had deterioration in BCVA. The final BCVA was significantly correlated with the amplitude and latency of mfERG in all nine sectors, and the amplitude had a stronger correlation than latency. The foveal ellipsoid zone of the photoreceptors and external limiting membrane (ELM) status, as well as the retinal thickness in most sectors, were also correlated with the final BCVA. In a multivariate linear regression model, age, pre-PRP BCVA, amplitude of mfERG in the central sector, and foveal ellipsoid zone status were significantly correlated with the final BCVA. The retinal thickness was correlated with the amplitude or latency of mfERG in some sectors, and the correlation was tighter in temporal and inferior sectors.

CONCLUSIONS

A lower amplitude of mfERG and disrupted foveal ellipsoid zone status were significantly correlated with a worse visual prognosis in diabetic eyes after PRP.

Comparison of conventional pattern and novel navigated panretinal photocoagulation in proliferative diabetic retinopathy

PURPOSE

To compare the laser spot quality between the conventional slit lamp pattern laser (PASCAL) and the navigated pattern laser (NAVILAS) for panretinal photocoagulation (PRP).

METHODS

Prospective randomized interventional trial of 73 eyes (51 patients) with high-risk proliferative diabetic retinopathy. Eyes underwent PRP using 30-ms pulse duration with either PASCAL (16 eyes) or NAVILAS laser (21 eyes), or 100-ms pulse duration with either PASCAL (16 eyes) or NAVILAS laser (20 eyes). Fundus color images of all quadrants were taken 5 minutes after treatment. Laser burn size (major and minor diameter and area) and ellipticity (ratio of minor to major axis) were analyzed across the retina. Treatment time and pain were compared between both groups.

RESULTS

The burn size variation in navigated laser 30 ms, 100 ms, and conventional pattern 30 ms and single-spot 100 ms laser was 22%, 24%, 21%, and 35%, respectively. The variation of the laser burn area near the arcade for NAVILAS and for PASCAL was 29% and 22%, respectively (P < 0.01). Closer to the equator, burns from the NAVILAS showed even smaller variation of 15% compared with 25% with PASCAL (P < 0.005). Laser spots from PASCAL exhibited an increasing elliptical shape toward the periphery, whereas NAVILAS laser spots tended to be more uniform all over the retina. Average treatment duration and pain experience was less with navigated laser compared with pattern laser (P ≤ 0.05).

CONCLUSIONS

Navigated laser treatment achieves more uniform laser burns with less pain during shorter treatment duration in comparison with conventional pattern laser.