Argon Green Laser Research Articles

Does conventional laser photocoagulation still have a place in the treatment of diabetic macular edema?

Objective: The study aimed to investigate the long-term efficacy of conventional laser photocoagulation in the treatment of diabetic macular edema.Methods: In this retrospective study, the records of patients presented with diabetic macular edema (DME) and non-proliferative diabetic retinopathy were reviewed. DME defined as clinically significant macular edema was treated by using argon green or yellow dye laser with focal, grid, and modified grid techniques according to Early Treatment Diabetic Retinopathy Study parameters. Best-corrected visual acuity (BCVA) was measured. BCVA change after the treatment and its relationship with other factors were evaluated.Results: The study included 133 eyes of 81 patients. The mean follow-up was 28.26 months. BCVA demonstrated the increase of 2 lines or more in 20.7% of the eyes, stabilization within 2 lines in 60.7% of the eyes, and loss of 2 lines or more in 18.3% of the eyes. The eyes with baseline BCVA lower than or equal to 0.50 showed a statistically significant increase (p=0.001) whereas the eyes with baseline BCVA of more than 0.50 did not show a statistically significant change (p=0.070) after laser photocoagulation treatment.Conclusions: Conventional laser photocoagulation is an effective treatment in diabetic macular edema including center-involved type and stabilizes visual acuity in the majority of the patients. Improvement in BCVA is significant in the group with lower baseline BCVA.Abbreviations: DM = diabetes mellitus, DME = diabetic macular edema, ETDRS = early treatment diabetic retinopathy study, CSME = clinically significant macular edema, CLP = conventional laser photocoagulation, VEGF = vascular endothelial growth factor, BCVA = best-corrected visual acuity, ANOVA = analysis of variance, VA = visual acuity

Longitudinal Changes in Retinal Blood Flow in a Feline Retinal Vein Occlusion Model as Measured by Doppler Optical Coherence Tomography and Optical Coherence Tomography Angiography.

PurposeWe aimed to observe longitudinal changes in retinal blood flow (RBF) and structural transformations in capillaries using Doppler optical coherence tomography (DOCT) and optical coherence tomography angiography (OCTA) in a feline retinal blood occlusion (RVO) model.MethodsRVO was induced by argon green laser photocoagulation (PC) in six eyes of six cats. RBF was measured at a first-order retinal artery and vein by a DOCT flowmeter, and structural changes in the capillaries around the occluded vessels (12 × 12 and 3 × 3 mm) were assessed by OCTA before (at baseline); immediately after PC; and on days 1, 4, 7, and 14 thereafter. Systemic and ocular parameters were monitored during the observation period.ResultsThere were no significant differences in any systemic or ocular parameters before and after PC. Arterial RBF increased significantly on day 1 (160.6 ± 8.6% vs. baseline, P < 0.001) and decreased below baseline after day 1 through 14. Venous RBF decreased immediately after PC (17.4 ± 9.6% vs. baseline, P = 0.001) and then gradually increased afterwards, but did not return to baseline. OCTA showed dilatation of retinal venules immediately after PC to day 1. Collateral vessels began to form on day 4, had matured by day 7, and were pruned on day 14, which formed as mature as normal retinal venule diameters.ConclusionsWith increasing arterial RBF within 1 day after inducing RVO, venules gradually expanded to form collateral vessels, suggesting that collateral vessels originate from existing capillary networks, not neovascularization.

Effects of Laser Peripheral Iridotomy in Primary Angle Closure Suspect in asymptomatic patients (PACS) and complications of Laser Peripheral Iridotmy.

Objective: The Effect of laser peripheral iridotomy in&nbsp; Primary Angle Closure&nbsp; suspect in asymptomatic patients and complications of laser peripheral iridotomy. A single institutional study. This study’s aims to evaluate the&nbsp; effectiveness of Laser peripheral iridotomy(LPI)&nbsp; in&nbsp; eyes with&nbsp; asymptomatic&nbsp; primary angle closure suspect&nbsp; patients. We plan to conduct a retrospective chart review of patients who underwent an LPI , procedure by one glaucoma sub-specialist at Malabar Medical College and Hospital(MMC &amp;H) between January 2017 and December2018. Patients were treated with argon green laser and Nd: Yag&nbsp;&nbsp; laser applications over&nbsp; iris at 7 &amp; 4 clock&nbsp; in one session. Data obtained will include patients’ demographics, sub-type of glaucoma, baseline IOP, Visual Fields, OCT RFNL,&nbsp; number of anti-glaucoma medications, and post- laser IOP at 1 hour. LPI outcomes at 4, 12&nbsp; and 24weeks post laser will be evaluated by&nbsp; slit lamp examination and four mirror gonioscopy&nbsp; to know the patency of iridotomy. Statistical analyses will be performed comparing&nbsp; patency of iridotomy. Data on presence and degree of transient IOP rise 1-hour post procedure , complication of iridotomy will also be obtained. Design and setting: A retrospective study, A single institutional study. Materials and Methods: In this retrospective study, 67 adult cases of 134 eyes of&nbsp; Primary&nbsp; angle closure&nbsp;&nbsp; suspect(PACS) asypmtomatic patients&nbsp; were underwent 4-mirror zeiss gonioscopy&nbsp; before LPI procedure and slit lamp by Van Hericks ,OCT RFNL,HFA 24-2 Sita Standard ,stereioscopic&nbsp; fundus pictures enrolled into the study from out-patients Department of ophthalmology&nbsp; MMC &amp;H, Calicut for studies between January 2017 and&nbsp; December 2018. Inclusion criteria: All patients who underwent LPI treatment during above mentioned period were included. Exclusion criteria: Eyes&nbsp; with corneal scar, very shallow anterior chamber , neovascular glaucoma , Iridocorneal Endothelial syndrome(ICE) ,previous ALT/ SLT patients, unco-operative patients and&nbsp; Uveitis patients. Main outcome and Measure: To measure&nbsp; the patency of iridotomy at 4,&nbsp; 12 and 24weeks of post&nbsp; LPI treatment, to know the effects on&nbsp; angle of PACS patients. Statistical analyses will be performed comparing baseline&nbsp; gonioscopy&nbsp; with post-laser&nbsp; gonioscopy&nbsp; at4,12 and&nbsp; 24 weeks. Successful outcome will be defined as&nbsp; two&nbsp; or more&nbsp; ITC angles are open after LPI with no need for further&nbsp;&nbsp; medication or&nbsp;&nbsp; laser. Results: A total of 134 eyes in 67 patients participated in this study. All 134 glaucoma eyes were treated with LPI. The&nbsp; 134 eyes with Successful opening&nbsp; of angle more than 2 for at least 24 weeks. Follow-up ranged from 4 to 24 weeks. Gonioscopy was performed&nbsp; in each&nbsp; visit to confirm the angle status and patency of iridotomy.Success is defined as opening ofmore than&nbsp; 2 angles ITC for at least 24&nbsp; weeks, with no need for further&nbsp;&nbsp; medication&nbsp; or laser treatment. The percentage of open angle at 4 weeks was more 2 angles in 36eyes(26.9%), ITC&gt;3 angles in 28eyes, (20.9%) and&nbsp; ITC&gt;4 angles in 70eyes are&nbsp; (52.2%) ,at 12weeks&nbsp; more 2 angles24eyes (17.9%), ITC&gt; 3angles in ,30 eys(20.9%) ITC&gt;4 angles in&nbsp; 80 eyes(59.7%)&nbsp; and 24 weeks&nbsp; was more 2 angles14 eyes(10.4%), ITC&gt; 3,30eyes (22.4%) ITC&gt;4 angle in90 eyes (67.2%) .&nbsp; The success rate&nbsp; at 24 weeks&nbsp; ITC&nbsp; more than2 angle was 10.4%&nbsp; ,&nbsp; ITC&gt;3angles 22.4%&nbsp; and ITC&gt; 4angles in&nbsp; 67.2% respectively.In all cases, IOP was measured within 1 hour and IOP elevation of greater than 8 mm Hg was observed in&nbsp; eyes21 (15.7%) . Mild-to-moderate anterior chamber reaction is seen in 64eyes&nbsp; ,hyphema in 6 eyes, ghost images seen in 2 eyes,2 cases of macular edema, cataract&nbsp; progression&nbsp; seen in 16eyes,and closureof iridotomy in 26eyes&nbsp; were noted. Post laser procedure&nbsp;&nbsp; combination of steroid and antibiotic&nbsp; medication was prescribed for 5 days&nbsp; and IOP pressure more&nbsp; 8 mmHg seen in 21 eyes(15.7%) ,antiglaucoma medications&nbsp; started&nbsp; and oral T. Diamox 250mg 2 tablets wre prescribed followed up after 5 days to reasess the IOP. Conclusions:&nbsp; LPI &nbsp;is an effective treatment option for&nbsp; all patients with&nbsp;in&nbsp; Primary Angle Closure&nbsp; suspect to prevent the acute angle closure glaucoma.LPI&nbsp; is a effective, compliance-free, repeatable,most PACS eyes don’t receive further treatment and safe therapeutic modality having only minor, transient, self-limiting or easily controlled side effects with no sequelae. Progression to PACG is uncommon in PACS and PAC. Despite our methodology, the inherent limitations of studies should be considered, and conclusion drawn from our pooled results should be interpreted with caution. Future large-volume, well-designed with extensive follow-up are awaited to confirm and update the findings of this analysis

Effect of vitrectomy with intrasurgical regulation of intraocular pressure in a rabbit model of central retinal artery occlusion

Central retinal artery occlusion (CRAO) is an ophthalmic emergency that causes severe and permanent visual impairment. The effects of conventional treatments on recanalizing retinal arteries and improving visual outcome are equivocal. This study was designed to determine the possible benefits of pars plana vitrectomy (PPV) with intrasurgical regulation of intraocular pressure using intraocular vascular counterpulsation (IVT). CRAO was induced by 532-nm argon green laser activation of auricular intravenous injected rose bengal, a photosensitive dye, in the central retinal arteries (CRA) of eighty-four New Zealand white albino rabbits. CRAO rabbits were randomly assigned to photocoagulation, vitrectomy and counterpulsation groups. Depending on the time intervals between surgery and CRAO induction, vitrectomy and counterpulsation groups were further divided into 2 h (2h), 6 h (6h) and 24 h (24h) subgroups. The proportion of eyes with complete recanalization was significantly higher in the 2h counterpulsation subgroup after three days (P = 0.032) and in all counterpulsation subgroups after one week (P = 0.020). After one month, the 2h and 6h counterpulsation subgroups showed greater oscillatory potential (OPs) responses (F = 3.519, P = 0.049). The 2h counterpulsation subgroup also exhibited greater b-wave amplitude in photopic 3.0 Flicker(F = 4.530, P = 0.044). Histologic evaluation revealed less destruction in the inner retina for the 2h and 6h counterpulsation subgroups. Expression of HSP70 was higher in the 2h and 6h counterpulsation subgroups (F = 48.915,P < 0.001). Levels of HSP90 were lower in all counterpulsation subgroups (F = 30.065,P < 0.001). Levels of TNF-α were lower in the 2h counterpulsation subgroup (F = 14.762,P < 0.001). These results indicate that PPV with IVT was effective to recanalize retinal arteries after CRAO. Early intervention provided better morphologic and functional prognosis for inner retina. The protective effect was related with higher retinal levels of HSP70 and lower levels of HSP90 and TNF-α.

Clinical Efficacy and Safety of Current Interventions for Choroidal Neovascularization Associated with Rare Diseases: A Systematic Literature Review.

The aim of this systematic literature review was to evaluate the efficacy and safety of interventions for the treatment of choroidal neovascularization (CNV) secondary to etiologies other than age-related macular degeneration and pathologic myopia. Relevant randomized controlled trials (RCTs) and prospective observational studies were identified by searching MEDLINE, MEDLINE In-Process, EMBASE, and CENTRAL. The search identified 5 RCTs; no relevant observational studies were identified. The studies differed in terms of underlying cause of CNV, patient numbers (n = 9-178), follow-up time (2-36months) and quality assessment. In the largest RCT (n = 178 across a range of rare CNV etiologies), intravitreal ranibizumab showed superior efficacy versus sham from baseline to month 2 [mean best-corrected visual acuity (BCVA): + 9.5 vs. - 0.4 letters; p < 0.001]; the gain was maintained up to month 12. In the treatment of CNV secondary to presumed ocular histoplasmosis syndrome (POHS), both intravitreal ranibizumab and photodynamic therapy (PDT) showed significant improvement from baseline BCVA over the 12-month period (n = 9); however, all patients in the PDT group required rescue ranibizumab therapy. Unlicensed intravitreal bevacizumab was associated with a statistically significant improvement in BCVA compared to PDT at 12months (p < 0.001) in patients with CNV secondary to multifocal choroiditis (n = 27). The use of steroids before PDT showed better BCVA outcomes than PDT alone (p < 0.05) in patients with idiopathic CNV (n = 20). Argon green laser therapy showed limited efficacy in patients with CNV secondary to OHS (n = 134). There is evidence from a relatively large, good-quality study to support the use of intravitreal ranibizumab for the treatment of CNV secondary to rare diseases. However, the limited number of RCTs for this indication and differences in study characteristics between RCTs mean that there is uncertainty regarding comparative clinical effectiveness of interventions. RCTs with an active comparator are required to fully establish the comparative effectiveness of treatments for CNV secondary to rare diseases. Novartis Pharmaceuticals UK Ltd, Surrey, UK.

Longitudinal Measurement of Hemodynamic Changes within the Posterior Optic Nerve Head in Rodent Nonarteritic Anterior Ischemic Optic Neuropathy.

Objective To assess the in vivo dynamic blood flow features of posterior optic nerve head (ONH) in rat model of nonarteritic anterior ischemic optic neuropathy (rNAION). Methods rNAION was established with Rose Bengal and argon green laser in Sprague-Dawley rats. Fundus photography and fundus fluorescein angiography (FFA) were performed to assess the dynamic changes of optic disc in morphology in 90 days and in blood perfusion in 3 hours after the induction of disease. Histological examinations were performed to evaluate the success of modeling. The dynamic blood flow kinetics of posterior ONH in rNAION were measured by Laser Doppler Flowmetry (LDF) on the day 3, 7, 14, 21, and 40 after the disease induction. One-way ANOVA, Student's t-test and Bonferroni adjustment were used for multiple comparisons of kinetic measurements of blood flow. Results Optic disc edema and subsequent resolution associated with the development of optic disc pallor were observed in rNAION. FFA showed that the optic disc was hypofluorescence in the early phase and hyperfluorescence in the late phase. Histological studies suggested edema and loosened tissues of ONH, loss of retinal ganglion cells (RGCs), optic nerve substance and gliosis. Compared to the naive rats, the blood flow kinetics of posterior ONH in rNAION significant reduced at each time point after modeling (F=175.06, P<0.0001). The reductions were specifically remarkable in 14 days after the disease induction (All P<0.01). Conclusions Continuous blood perfusion reduction was found in rNAION, with significant alteration in 14 days after disease induction. Our results provided important information for understanding the hemodynamic changes in rNAION.

Evaluation of optic nerve head blood flow in normal rats and a rodent model of non-arteritic ischemic optic neuropathy using laser speckle flowgraphy

To evaluate optic nerve head (ONH) blood flow in normal rats and a rodent model of non-arteritic ischemic optic neuropathy (rNAION) in vivo using laser speckle flowgraphy (LSFG). Rats were under general anesthesia; to induce NAION, Rose Bengal (RB) was injected into the tail vein. After the administration of RB, the left ONH was photoactivated using an argon green laser. We measured ONH blood flow in the normal rats and the rNAION group (at 1, 3, 7, 14, and 28 days after the induction of NAION) using an LSFG-Micro. We used the mean blur rate (MBR) of the vessel region (MV) and MBR of the tissue region (MT) as indicators of blood flow. We compared the MBR of the right and left eyes in both the normal rats and the rNAION group. In the normal rats, there were no significant differences in MV or MT between the right and left eyes. In the rNAION group, the MV and MT of the affected eyes were significantly lower than those of the unaffected eyes at all time points. There were significant differences between the left/right MV and MT ratios seen before the induction of NAION and those observed at 1, 3, 7, 14, and 28 days after the induction of NAION. However, there were no significant differences in these parameters among any of post-NAION induction time points. Our results indicated that the ONH blood flow of the rNAION rats fell in the acute and chronic phases.

Clinical observation of the efficacy of Bevacizumab combined with argon green laser in treating fundus macular edema.

We studied the clinical efficacy of Bevacizumab combined with argon green laser in treating fundus macular edema. From May 2009 to April 2013, 78 patients seeking treatment for macular edema in the First Affiliated Hospital of Nanchang University were enrolled in this study. Patients were randomly divided into two groups: i) The experimental group (n=39) and the control group (n=39). Patients in the experimental group were treated with Bevacizumab (Avastin®) combined with argon green laser, and those in the control group were treated exclusively with argon green laser. Therapeutic effects were compared, and postoperative adverse reactions caused by both treatment methods were compared. Our results showed that, after treatment, the macular foveal thickness was reduced noticeably in both groups, while the therapeutic effect of combined treatment was more prominent. Patients in the experimental group gained the best-corrected visual acuity after one month of treatment, while patients in the control group achieved that after three months of treatment. We concluded that the use of Avastin® combined with argon green laser was safe and effective. Visual acuity was improved obviously with minimum adverse reactions.

Murine fundus fluorescein angiography: An alternative approach using a handheld camera

In today’s modern pharmacologic approach to treating sight-threatening retinal vascular disorders, there is an increasing demand for a compact, mobile, lightweight and cost-effective fluorescein fundus camera to document the effects of antiangiogenic drugs on laser-induced choroidal neovascularization (CNV) in mice and other experimental animals. We have adapted the use of the Kowa Genesis Df Camera to perform Fundus Fluorescein Angiography (FFA) in mice. The 1 kg, 28 cm high camera has built-in barrier and exciter filters to allow digital FFA recording to a Compact Flash memory card. Furthermore, this handheld unit has a steady Indirect Lens Holder that firmly attaches to the main unit, that securely holds a 90 diopter lens in position, in order to facilitate appropriate focus and stability, for photographing the delicate central murine fundus. This easily portable fundus fluorescein camera can effectively record exceptional central retinal vascular detail in murine laser-induced CNV, while readily allowing the investigator to adjust the camera’s position according to the variable head and eye movements that can randomly occur while the mouse is optimally anesthetized. This movable image recording device, with efficiencies of space, time, cost, energy and personnel, has enabled us to accurately document the alterations in the central choroidal and retinal vasculature following induction of CNV, implemented by argon-green laser photocoagulation and disruption of Bruch’s Membrane, in the experimental murine model of exudative macular degeneration.

Exudative vasculopathy in a child with Leber congenital amaurosis

Leber congenital amaurosis is a severe retinal dystrophy that causes blindness or severe visual impairment, usually before the age of 1 year. We present the case of a 13-year-old girl with Leber congenital amaurosis who developed an exudative vasculopathy. She was successfully treated with cryotherapy and argon green laser. To our knowledge, only 4 cases of this condition in patients with Leber congenital amaurosis have been reported previously. This phenotype may be related to c.2991+1655A>G (p.Cys998X) mutations in the CEP290 gene.

New Approach for Conjunctivochalasis Using an Argon Green Laser

To evaluate the effectiveness of conjunctivoplasty using an argon green laser in symptomatic patients with conjunctivochalasis (CCh). Twenty-nine eyes of 18 patients with various grades of CCh were included in this study. All the patients, who were refractory to the conventional therapy, were treated using an argon green laser. The ocular symptoms and signs, including the CCh grade, the tear Ocular Surface Disease Index, the breakup time, the Schirmer test, and the abnormal ocular surface findings, were evaluated preoperatively and postoperatively. The mean age of the patients was 69.1 ± 8.4 years. The grade of CCh in 25 eyes (86%) decreased at 6 months after the laser conjunctivoplasty. When the grade reduction rates were calculated, the reduction rates of grades 1, 2, and 3 were 100%, 69%, and 48%, respectively. Most of the patients showed a significant symptomatic improvement, and the Ocular Surface Disease Index scores decreased from 0.41 to 0.22 (P < 0.001). The breakup time increased from 9.1 to 10.2 (P = 0.007), but the Schirmer test results did not show any differences after the surgery (P = 0.257). Conjunctivoplasty using an argon green laser is a simple and effective choice to treat symptomatic patients with CCh, especially in cases of mild-to-moderate grade CCh.

Acute variations in retinal vascular oxygen content in a rabbit model of retinal venous occlusion.

PurposeTo study the variation in intravascular oxygen saturation (oximetry) during an acute retinal vein occlusion (RVO) using hyperspectral computed tomographic spectroscopy based oximetry measurements.MethodsThirty rabbits were dilated and anesthetized for experiments. Baseline oximetry measurements were made using a custom-made hyperspectral computed tomographic imaging spectrometer coupled to a fundus camera. RVO were induced using argon green laser following an intravenous injection of Rose Bengal. RVO induction was confirmed by fluorescein angiography. Retinal oximetry measurements were repeated in arterial and venous branches one hour after RVO induction and up to 4 weeks afterwards. Comparison of retinal oximetry before and after vein occlusion was made using the Student T-test.ResultsOne hour after RVO induction, we observed statistically significant reductions in the intravascular oxygen saturation in temporal retinal arteries (85.1±6.1% vs. 80.6±6.6%; p<0.0001) and veins (71.4±5.5% vs. 64.0±4.7%; p<0.0001). This decrease was reversible in animals that spontaneously recannulated the vein occlusion. There were no statistically significant differences in oxygen saturation in the nasal control arteries and veins before and after temporal vein RVO induction.ConclusionsWe demonstrate, for the first time, acute changes in the intravascular oxygen content of retinal vessels 1 hour after RVO. These changes are reversible upon spontaneous recannulation of retinal vessels. This study demonstrates that hyperspectral computer tomographic spectroscopy based oximetry can detect physiological variations in intravascular retinal oxygen saturation. The study also provides the first qualitative and quantitative evidence of the variation in retinal vascular oxygen content directly attributable to an acute retinal vein occlusion.

Laser Clearance of Drusen Deposit in Patients With Autosomal Dominant Drusen (p.Arg345Trp in EFEMP1)

To assess whether laser treatment to the retinal pigment epithelium anterior to drusen in eyes of patients with EFEMP1-related maculopathy affects visual acuity, deposit volume, and retinal sensitivity. Prospective, interventional case series. In 11 patients with autosomal dominant drusen and confirmed disease-causing EFEMP1 mutation, the worse-seeing eye was treated with Argon green laser (10 to 15 laser spots; 200-μm spot size, 0.1-second duration, 80 to 120 mW). Patients were examined before treatment as well as 1, 3, 6, and 12months after the procedure. Clinical assessment included visual acuity, fundus-controlled perimetry, spectral-domain optical coherence tomography, and autofluorescence imaging. Custom-made software allowed for coregistration of fundus-controlled perimetry and spectral-domain optical coherence tomography data sets. The main outcome measures were change in visual acuity, retinal sensitivity, and drusen volume. The untreated eyes lost an average of 0.8 letters, whereas the treated eyes gained an average of 4.9 letters. For fundus-controlled perimetry, locus-by-locus differences in sensitivity were calculated between pretreatment and posttreatment assessments; subsequently, the overall difference in the treated and untreated eye was compared. Five patients showed significant improvement in retinal sensitivity, 5 patients showed no change, and 1 patient showed significant deterioration. An increase in mean drusen thickness was observed in the untreated eyes, but not in the treated eyes (P= .0322). The thickness of the drusen correlated with retinal sensitivity (ρ=-0.49; P < .0001). Safety was demonstrated and no adverse events were observed. Low-energy laser treatment is safe andmay be effective in the treatment of autosomal dominant drusen. Further evaluation with long-term assessment is required to confirm the benefits.

Rodent model of nonarteritic ischemic optic neuropathy and its electrophysiological evaluation

Our aim was to establish a rodent model of nonarteritic ischemic optic neuropathy (rNAION). To induce rNAION, after administration of Rose Bengal (RB) (2.5 mM), the small vessels of the left optic nerve were photoactivated using a 514-nm argon green laser with about 500-μm spot size for 12 s (RB-laser induction). To evaluate the induction, funduscopic examination, fluorescein angiography (FA), visualization of capillaries within the optic disc, histologic evaluation, and electrophysiological testing were performed. In the RB-laser-induction eyes, the optic disc became swollen on day 3 followed by atrophy on week 8. FA showed filling defects in the choroid and optic disc at an early stage, followed by hyperfluorescence at a late stage. The capillaries within the optic disc were reduced markedly. Histopathologic examination showed acellular nerve fiber layer (NFL) swelling anterior to the optic disc. The morphologic retinal changes were apparent only in the retinal ganglion cell (RGC) layer, with a reduction in the number of cells. Visually evoked potential (VEP) amplitude decreased significantly, but electroretinography (ERG) showed no significant difference. The positive scotopic threshold response (pSTR) was not reduced on the 1st day but was significantly reduced 3 days after induction. The findings are similar to human NAION. Therefore, RB-laser induction is well suited to establish the presence of rNAION.

KRYPTON RED LASER PHOTOCOAGULATION OF THE OCULAR FUNDUS

The theoretical rationale, the histopathologic evidence, and the preliminary clinical studies related to krypton red laser (KRL) photocoagulation of the ocular fundus are reviewed. The authors report on their experience with currently available laser systems using this wavelength (647.1 nm) for photocoagulation of retinal vascular proliferative diseases and chorioretinal diseases associated with exudative manifestations. A histopathologic and clinical comparison of argon blue-green laser (ABGL), the pure argon green laser (AGL), and the krypton yellow laser (KYL), with reference to photocoagulation treatment of the ocular fundus is also discussed.

A new technique: argon green laser–Nd:YAG laser combination for the treatment of premacular haemorrhage

A new technique: argon green laser–Nd:YAG laser combination for the treatment of premacular haemorrhage

Argon Laser Photocystotomy of a Vitreous Cyst.

Free-floating idiopathic vitreous cysts are rare entities. For symptomatic patients, treatment options include laser photocystotomy or pars plana vitrectomy (PPV) with cyst excision. Historically, size of the cyst impacted treatment approaches. Laser treatments have been used for smaller cysts ranging 3 to 5 mm in diameter. PPV has been utilized for cysts larger than 4 mm. Successful laser photocystotomy has been reported, utilizing both argon and Nd: YAG lasers. Herein, we present a case of successful argon laser photocystotomy of a 7.1 mm diameter vitreous cyst, the largest documented cyst ever treated. Treatment should be individualized based on patient age, ability to cooperate in an office setting, phakic status, status of the posterior hyaloid, cyst morphology, and location. In our case, because of pigment on the anterior cyst surface, and the presence of an attached posterior hyaloid, the argon green laser was used.

Multifocal electroretinography amplitudes increase after photocoagulation in areas with increased retinal thickness and hard exudates

This study aimed to evaluate local response on multifocal electroretinography (mfERG) and to assess retinal thickness with optical coherence tomography (OCT) after focal laser treatment in areas with retinal oedema and exudates in patients with diabetic retinopathy. Twelve diabetes patients (aged 60 +/- 14 years, diabetes duration 16 +/- 8 years) treated with focal or grid photocoagulation in areas with retinal oedema and/or exudates underwent mfERG and OCT before and 3 months after treatment. The average thickness (in microm) in any of the nine sectors (defined according to the ETDRS) treated with photocoagulation was measured. Amplitudes and implicit times were analysed in corresponding areas on the mfERG. Mean mfERG amplitudes increased after photocoagulation (21.5 +/- 8.0 nV/deg(2) versus 16.8 +/- 6.1 nV/deg(2); p = 0.012), whereas no difference was seen in implicit times. Mean OCT values in the treated regions were lower at follow-up (272 +/- 23 microm versus 327 +/- 79 microm; p = 0.013). No correlation was seen between changes in mfERG response and changes in OCT values. The decrease in retinal thickness was correlated with the number of laser spots applied (p = 0.002). Focal argon laser treatment is effective in reducing retinal thickness. In addition, treated areas tend to show improved retinal function as demonstrated by increased amplitudes on mfERG.

Effects of conventional argon panretinal laser photocoagulation on retinal nerve fibre layer and driving visual fields in diabetic retinopathy

To determine the effects of argon green panretinal laser photocoagulation on retinal nerve fibre layer thickness, threshold visual fields, and Estermann full-binocular visual fields over time in diabetic retinopathy. Prospective, pilot clinical study. Time-domain optical coherence tomography (TD-OCT) of the optic nerve head and 24-2 SITA-Fast Humphrey/Estermann visual fields (HVF, EVFs) recorded at baseline, 10 weeks, and 6 months post laser. Quantitative field analysis of central 10 degrees, 24 degrees, and binocular visual fields. A total of 10 eye samples were subjected to uncomplicated multiple-session 100 ms panretinal laser using 2000 burns, 300-microm spot, and mean power of 136 mW (SD+/-39.3). TD-OCT detected and quantified an increase in mean retinal nerve fibre layer thickness at 10 weeks (+8 microm; P<0.05) and progressive thinning at 6 months (-4 microm; P<0.05) compared with baseline. Mean threshold sensitivities, and 10 degrees and 24 degrees HVF improved at both time points in the majority (9 of 10 and 8 of 10) of patients. EVFs showed no significant change with treatment. This pilot study shows that conventional argon laser panretinal photocoagulation may increase the retinal nerve fibre layer thickness in the short term, presumably related to laser-induced axonal injury, with progressive thinning of nerve fibre layer over the long term. The 10 degrees and 24 degrees visual fields improved significantly after laser with no adverse effects on the UK standard driving fields.

Effects of conventional argon panretinal laser photocoagulation on retinal nerve fibre layer and driving visual fields in diabetic retinopathy

Abstract Purpose To determine the effects of argon green panretinal laser photocoagulation (AG‐PRP) on retinal nerve fibre layer thickness (RNFLT), threshold visual fields (VF), and Estermann full binocular VF over time. Methods Prospective, pilot clinical study of patients with newly‐diagnosed proliferative diabetic retinopathy (PDR). Time‐Domain optical coherence tomography (TD‐OCT) of optic nerve head and 24‐2 SITA‐Fast Humphrey/Estermann VF (HVF, EVF) recorded at baseline, 10 weeks and 6 months post‐laser. Quantitative field analysis of central 10º, 24º, and binocular VF. Results 10 eyes underwent uncomplicated multiple‐session 100ms AG‐PRP using 2000 burns, 400μm spot, and mean power 136 mW (SD 39.3). TD‐OCT detected and quantified an increase in mean RNFLT at 10 weeks (+8 μm; p&lt;0.05) and progressive thinning at 6 months (‐4 μm; p&lt;0.05) compared to baseline. Mean threshold sensitivities, 10° and 24°, improved at both time‐points in the majority (9/10 and 8/10) of patients. Masked grading of EVFs showed no significant change with treatment. Conclusion This pilot study demonstrates that conventional AG‐PRP may increase the RNFL in the short‐term, presumably related to laser‐induced axonal injury, with progressive thinning of RNFL in the longer‐term. The sensitivity of both 10° and 24° VFs improved significantly following AG‐PRP, and this central functional improvement may be due to a reduction in oedema folowing AG‐PRP. Binocular standard driving VFs performed within 6 months of AG‐PRP may actually reflect pre‐existing VF abnormalities due to severe retinal ischaemia or non‐viable retina at presentation, rather than direct functional loss from laser.