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Since the first peer-reviewed publication on MicroPulse® Transscleral Laser Therapy (MP-TLT) in 2010, authors worldwide have used a wide range of treatment parameter combinations with varying clinical efficacy in terms of the magnitude of intraocular pressure reduction, success rate, durability, and safety profile. This has made it difficult to determine the proper parameters necessary to optimize efficacy and safety, and has made comparison of results from one investigation to another difficult. The first goal of this paper is to explain and highlight the impact of the choices of exposure time and the number of sweeps per hemisphere in terms of “sweep velocity” on energy delivery to the eye. These treatment parameters are underreported in the literature. The second goal is to introduce fluence as a “dose” metric, that combines all the treatment parameters and constants into a single number. Fluence may be a better light-dose metric and a more reliable indicator of clinical outcomes compared to total energy.

Purpose Self-administration of topical ophthalmic therapies remains challenging for many patients as errors due to improper technique are common. The aim of the current studies was to evaluate a novel electromechanical topical ocular drug delivery device designed to facilitate precise dosing and accurate delivery with substantially lower drug exposure than conventional eye drops. Patients and methods Two randomized Phase 1 studies were performed to evaluate the efficacy and safety of a single dose of a topical ophthalmic solution administered as a ~9 μL microfluid stream via the test device compared with a ~30-40 μL drop delivered via conventional dropper in healthy subjects (Trial 1) and glaucoma patients (Trial 2). In Trial 1, a 1% tropicamide/2.5% phenylephrine solution was administered via the test device in one eye and by conventional dropper in the contralateral eye. Pupil dilation was measured at 30 min intervals post-instillation and subject comfort was assessed using a visual analogue scale (range, 0-100). In Trial 2, patients were randomized to receive latanoprost 0.005% via the test device or conventional dropper. Intraocular pressure was measured at baseline and 4-8 hrs post-instillation. Results In Trial 1 (N=20), mean (SD) pupil diameter 30 mins post-instillation increased by 3.4 (0.9) and 3.5 (1.0) mm in the test and control eyes, respectively. The mean comfort score was 81.7 for the test device versus 57.3 for conventional dropper delivery. In Trial 2 (N=18), the mean change in intraocular pressure following administration of latanoprost was -5.0 (1.8) and -4.3 (3.3) mm Hg in the test and control groups, respectively. No serious adverse events were observed in either study. Conclusion Administration of a single dose of topical ophthalmic therapy via an electromechanical drug delivery device resulted in comparable effects on pupil dilation and intraocular pressure with lower drug exposure and increased patient comfort compared with conventional dropper delivery.

Purpose To investigate the short-term effects of highdensity 20-ms laser on macular thickness using Pascaltargeted retinal photocoagulation (TRP) and reduced fluence/minimally-traumatic panretinal photocoagulation (MT-PRP) compared to standard-intensity PRP (SI-PRP) in proliferative diabetic retinopathy (PDR). Methods Prospective randomised clinical trial. Treatment-naive PDR was treated with single-session 20ms Pascal 2500 burns photocoagulation randomised to one of three treatment arms (TRP:MT-PRP:SI-PRP). Primary outcome measure was change in central retinal thickness (CRT) on OCT. Secondary outcomes at 4 and 12 weeks post-laser included: OCT peripapillary nerve fibre layer (NFL) thickness; PDR disease regression on Optos angiography; SITA-Std visual fields (VF); and, visual acuity (VA). Results 30 eyes of 24 patients were studied, ten eyes/ arm. At 12 weeks, there were significant reductions in CRT after TRP (9.6 mm; 95% CI, 1.84 to 17.36; p=0.021) and MT-PRP (17.1 mm; 95% CI, 11 to 23.2; p=0.001), versus SI-PRP (+5.9 mm; 95% CI, -6.75 to 18.55; p=0.32). PDR regression was similar between groups (TRP 70%; MT-PRP 70%; SI-PRP 90%; κ=0.76). No significant changes in VA and NFL thickness developed between groups. The VF mean deviation scores increased significantly in all groups at 12 weeks ([TRP, +0.70dB; 95% CI, 0.07 to 1.48; p=0.07], [MTPRP, +0.63dB; 95% CI, 0.12 to 1.15; p=0.02], [SI-PRP, +1.0dB; 95% CI, 0.19 to 1.74; p=0.02]). There were no laser-related ocular complications. Conclusions This pilot study reports that high-density 20-ms Pascal TRP and MT-PRP using 2500 burns did not produce increased macular thickness or any ocular adverse events during the short-term.

Purpose: To investigate the clinical effects and safety of targeted pattern scan laser (Pascal) retinal photocoagulation (TRP) in proliferative diabetic retinopathy (PDR). Methods: Prospective and non-randomized study of 28 eyes with treatment-naive proliferative diabetic retinopathy (PDR). Single-session 20-ms-Pascal TRP strategy applied 1500 burns to zones of retinal capillary non-perfusion and intermediate retinal ischaemia guided by wide-field fluorescein angiography (Optos). Main outcome measures at 12 and 24 weeks included; PDR grade (assessed by two masked retina specialists); central retinal thickness (CRT); mean deviation (MD) using 24-2 Swedish interactive threshold algorithm (SITA)-standard visual fields (VF); and ETDRS visual acuity (VA). Results: Following primary TRP, there was PDR regression in 76% of patients at 12 weeks (κ = 0.70; p

Purpose Shorter pulses used in pattern scanning photocoagulation (10-20 milliseconds [ms]) tend to produce lighter and smaller lesions than the Early Treatment Diabetic Retinopathy Study standard 100-ms exposures. Smaller lesions result in fewer complications but may potentially reduce clinical efficacy. It is worthwhile to reevaluate existing standards for the number and size of lesions needed. Methods The width of the coagulated zone in patients undergoing retinal photocoagulation was measured using optical coherence tomography. Lesions of "moderate," "light," and "barely visible" clinical grades were compared for 100, 200, and 400 μm spot sizes and pulse durations of 20 ms and 100 ms. Results To maintain the same total area as in 1,000 standard burns (100 ms, moderate) with a 400-μm beam, a larger number of 20-ms lesions are required: 1,464, 1,979, and 3,520 for moderate, light, and barely visible grades, respectively. Because of stronger relative effect of heat diffusion with a smaller beam, with 200 μm this ratio increases: 1,932, 2,783, and 5,017 lesions of 20 ms with moderate, light, and barely visible grades correspond to the area of 1,000 standard burns. Conclusion A simple formula is derived for calculation of the required spot spacing in the laser pattern for panretinal photocoagulation with various laser parameters to maintain the same total coagulated area.

Background and Objective: A novel computer-guided laser treatment for open-angle glaucoma, called patterned laser trabeculoplasty, and its preliminary clinical evaluation is described. Patients and Methods: Forty-seven eyes of 25 patients with open-angle glaucoma received 532-nm laser treatment with 100-μm spots. Power was titrated for trabecular meshwork blanching at 10 ms and sub-visible treatment was applied with 5-ms pulses. The arc patterns of 66 spots rotated automatically after each laser application so that the new pattern was applied at an untreated position. Results: Approximately 1,100 laser spots were placed per eye in 16 steps, covering 360° of trabecular meshwork. The intraocular pressure decreased from the pretreatment level of 21.9 ± 4.1 to 16.0 ± 2.3 mm Hg at 1 month (n = 41) and remained stable around 15.5 ± 2.7 mm Hg during 6 months of follow-up (n = 30). Conclusion: Patterned laser trabeculoplasty provides rapid, precise, and minimally traumatic (sub-visible) computer-guided treatment with exact abutment of the patterns, exhibiting a 24% reduction in intraocular pressure during 6 months of follow-up ( P < .01).

Background: The Pascal is a semiautomated photocoagulator that delivers a pattern array of multiple burns in a rapid predetermined sequence with a single foot pedal depression. Each burn is reduced to 10 or 20 ms to achieve this. The authors report their early experience with this system. Methods: 75 procedures done in 60 patients divided into four groups—group A, patients undergoing panretinal photocoagulation (PRP); group B, patients undergoing focal or modified grid macular laser; group C, patients undergoing macular grid and group D, patients undergoing retinopexy—were retrospectively studied. Results: 31/34 procedures in group A, 24/26 procedures in group B, 5/7 procedures in group C and all eight patients in group D had successful outcomes. Significantly higher powers were required with the Pascal than with conventional laser (p

PURPOSE: To compare the cytotoxic and mutagenic effect of 213-nm and 193-nm laser radiation on cultured mammalian cells. METHODS: Chinese hamster lung (V79) cells were exposed to 193-nm radiation from an argon fluorine excimer laser or 213-nm radiation from a 5th harmonic Nd:YAG laser. The cytotoxic action of the lasers was compared by determining the number of V79 cell colonies that formed 1 week after irradiating cells with different doses of 193-nm or 213-nm laser radiation or with continuous wave 254-nm radiation. The cytotoxic action of the lasers on primary cultures of human corneal fibroblasts was also compared. The mutagenic potential of the lasers was compared by measuring the number of ouabain or 6-Thioguanine(6TG)-resistant V79 mutants that formed after exposing V79 cells to 193-nm or 213-nm radiation. RESULTS: The dose of 193-nm laser radiation that resulted in 37% survival (D37) of V79 cells was estimated to be 11.3 mj/cm2 compared to 3.2 mJ/cm2 for 213-nm laser radiation and 1.2 mJ/cm2 for 254-nm UV radiation. The mean number of ouabain-induced mutants induced at the D37 for 193-nm, 213-nm, and 254-nm laser radiation were 28, 166, and 279 mutants/107 cells, respectively. Continuous wave 254-nm radiation induced 6TGresistant colonies, but there was no significant induction of 6TG-resistant mutants by either laser. CONCLUSIONS: Although the in vitro data presented herein may or may not be meaningful to humans, the 213-nm Nd:YAG laser was more cytotoxic and mutagenic than the 193-nm excimer laser on cultured mammalian cells but was less cytotoxic and mutagenic than 254-nm radiation. [J Refract Surg 2002;18:529-534]

Dear Editor, Laser photocoagulation of the fovea is historically an accidental and sight-threatening complication rarely reported during routine treatment [1]. We present a case of inadvertent foveal laser photocoagulation during multi-spot Pascal macular grid laser. A 66-year-old woman presented with left branch retinal vein occlusion and non-resolving cystoid macular oedema (Fig. 1), and underwent macular laser treatment. Vision was 6/18, with an artificial fellow eye. The patient was comfortable during initial laser titration stages, using single-spot 10ms 100μm burns, (power 125mW;fluence 16 Joules/cm). Modified Pascal grid laser involved multispot arrays applied to the macula. During delivery of the first multi-spot array, the patient’s head moved suddenly away from the slit-lamp due to anxiety from the light flashes produced. Laser burns were inadvertently scattered across the foveal zone (Fig.1). Immediately postlaser, vision was 6/19. Routine fundus autofluorescence (AF) and OCT identified misdirected parafoveal burns, with a single burn overlying the anatomical fovea (Fig. 2). At day 3, vision was stable despite increased central retinal thickness (Fig. 1). Burns showed initial hyper-autofluorescence on serial AF, and the intraretinal hyper-reflectivity slowly resolved (Fig. 2) [2]. At 6 months, the anatomical foveal burn showed restoration of the inner and outer segment junction of the photoreceptors (Fig. 2). Vision was 6/9 and with barely-visible foveal burns (Fig. 1). Retrospective review of our laser logbook documented 3,932 Pascal laser procedures between 11 December 2006 and April 1 2011. Institutional Pascal auditing has not reported any operational or laser-related adverse events [3]. The prevalence of inadvertent foveal photocoagulation complication following Pascal is 0.025% (1/3,932) in our institution. The Pascal photocoagulator has safety mechanisms in place [4]. The inner row of Pascal spots is delivered in 132ms, theoretically below patients’ reaction time. Lowfluence 10–30ms pulse duration Pascal can minimize scarring [2, 5]. The foveal 10ms burns healed over time, with photoreceptor infilling and minimal retinal pigment epithelium damage [6]. After this case, we routinely advise patients pre-laser application about multi-spot Pascal light flashes. In borderline cases, single-spot laser strategies are recommended. Despite a potentially sight-threatening adverse event such as foveal photocoagulation, a pattern-spot laser system application of low fluence 10ms burns may not lead to long-term microstructural alterations on FD-OCT or visual complications. Funding support None

Objective To investigate the safety and efficacy of a new laser procedure using a q-switched 532-nm neodymium (Nd):YAG laser, also called "selective laser trabeculoplasty," to lower intraocular pressure (IOP) in patients with open-angle glaucoma (OAG). The laser parameters were set to selectively target pigmented trabecular meshwork (TM) cells without coagulative damage to the TM structure or nonpigmented cells. Design Nonrandomized, prospective, clinical trial. Participants Thirty eyes of 30 patients with uncontrolled OAG (OAG group) and 23 eyes of 23 patients with uncontrolled OAG treated previously with argon laser trabeculoplasty (ALT group) were observed for 4 to 26 weeks. Forty-four of the 53 eyes were observed for 26 weeks. Intervention Patients were treated with the Coherent Selecta 7000 (Coherent, Inc, Palo Alto, CA) frequency-doubled q-switched Nd:YAG laser (532 nm). A total of approximately 50 nonoverlapping spots were placed over 180° of the TM at energy levels ranging from 0.6 to 1.2 mJ per pulse. After surgery, patients were maintained with the identical drug regimen as that before treatment. Results Both the OAG and ALT groups showed similar IOP reductions over time. Seventy percent of patients in each group responded to treatment with an IOP reduction of least 3 mmHg. At 26 weeks of follow-up, mean IOP reduction was 5.8 mmHg (23.5%, P P P P Conclusion The selective laser trabeculoplasty appears to be a safe and effective method to lower IOP in patients with OAG and patients treated previously with ALT. A reduction of IOP can be achieved without coagulation of the TM.

Segmentation and removal of fibrocellular and fibrovascular membranes from the vitreous cavity and from the surface of the retina is an important step in vitreoretinal surgery for pathologies including diabetic traction retinal detachment, proliferative vitreoretinopathy, retinopathy of prematurity, penetrating trauma, and macular pucker. Although the vitreoretinal instrumentation has substantially developed, surgical approaches are limited to mechanical methods, such as use of microscisjsors or of the vitreous cutter for transection, and peeling with forceps or picks. In most cases, mechanical methods are successful; however, complications including hemorrhages and retinal breaks may be induced by excessive traction or difficulties of tissue engagement. In addition, in extreme cases with epiretinal membranes firmly adhered to the retina, the available mechanical methods are insufficient for the necessary removal of this tissue. The investigation of lasers as instruments for surgical maneuvers within the vitreous cavity or close to the surface of the retina is attractive because laser technology may offer advantages, such as sharper, tractionless cutting and ablation, finer control, and greater ease of surgical approach compared with conventional instruments. Infrared lasers, through the laser/tissue interaction of photothermal ablation, 29 and excimer lasers through the ablative photodecomposition, 27 are currently the best candidates for the incision and ablation of biological tissues within the eye.

* BACKGROUND AND OBJECTIVE: To evaluate the efficacy and safety of the erbium:yttrium- aluminum-garnet (Er: YAG) laser for choroidotomy as a means of performing external drainage of subretinal fluid with less risk of choroidal bleeding. * MATERIALS AND METHODS: The authors tested this application in a rabbit model of retinal detachment by evaluating the effects of EnYAG laser energy on the bare choroid at various energy settings (1, 2, 3, or 5 mj/pulse) and repetition rates (2, 4, 10, or 30 Hz). RESULTS: Although the choroid was not perforated at low energy and frequency settings, choroidotomy was successfully achieved as energy and repetition rate were increased. Through higher energy levels per pulse and higher repetition rates, choroidotomy was achieved at lower total energy levels. No retinal damage was detected after laser choroidotomy. Choroidal bleeding was noted in 2 of 97 eyes-, however, no subretinal hemorrhage occurred. * CONCLUSION: These results indicate that the Er: YAG laser may be a clinically useful tool for retinal reattachment surgery. [Ophthalmic Surg Lasers 1997;28:1011-1016.]

Purpose: To evaluate the advantages, disadvantages, safety, complications, and surgical applicability of an erbium:YAG laser system for maneuvers in vitreoretinal surgery. Methods: A prospective, consecutive trial of 68 eyes in 66 patients undergoing vitreoretinal surgery in which an erbium:YAG laser with graduated output from 0.2 to 5.0 mJ per pulse, repetition rate of 2 to 30 Hz, and equipped with a flexible fiber optic and interchangeable 20-gauge intraocular fiber optic endoprobes was used to perform specific maneuvers, including transection, incision, and ablation of membranes, retinotomy, vessel coagulation, iridectomy, and lens tissue ablation. The patients were treated in five centers in contemporary vitreoretinal surgical settings for surgical indications, including proliferative diabetic retinopathy, proliferative vitreoretinopathy, epiretinal membrane, and retinopathy of prematurity. Results: One hundred seventy-four maneuvers were performed with an overall surgical efficacy rating of excellent or good in 84% of maneuvers, ranging from a high of 100% for subretinal membrane transection to a low of 25% for coagulation of blood vessels. Complications included retinal break or photocoagulative injury in 5% of epiretinal membrane incisions, minor bleeding from transectod retinal vessels during 29% of retinotomies, and intraocular lens damage during two posterior capsuiotomies. The most significant limitation was the cautious pace used during maneuvers near the retinal surface. Conclusion: The erbium:YAG laser is capable of versatile new approaches offering precise tissue cutting and ablation in vitreoretinal surgical maneuver's with a high degree of safety. The main limitation encountered was the slow speed of certain critical maneuvers near the retina.

Purpose We tested the efficacy of an erbium:YAG laser for maneuvers in patients undergoing vitreoretinal surgery. Methods An erbium:YAG laser equipped with a flexible fiberoptic and interchangeable 20-gauge endoprobes of various tip configurations ranging from 100 to 365 μm was used for specific maneuvers in 13 patients referred for vitreoretinal surgery for diabetic traction detachment, proliferative vitreoretinopathy, retinal detachment with posterior break, and epimacular membrane. The following maneuvers were performed: (1) transection of elevated vitreous membranes, (2) incision of epiretinal membranes, (3) drainage and relaxing retinotomy, (4) transection of subretinal membranes, (5) noncontact ablation of epiretinal membranes in air-filled eyes, (6) ablation of lens remnants, (7) posterior capsulotomy, (8) iris surgery, and (9) retinal vascular coagulation. Results Forty-eight defined maneuvers were performed with energy levels ranging from 0.2 to 5.0 mJ and repetition rates of 2 to 30 Hz. Transection of elevated membranes, subretinal membranes, and retinotomies were easily performed. Fourteen incisions into vascularized epiretinal membranes in diabetic traction detachment surgery demonstrated a fine margin of coagulation that permitted hemostatic incision. Retinal breaks were created during one of these incisions. Lens remnant ablation, posterior capsulotomy, and iris tissue removal were successful, with a single complication consisting of damage to the posterior surface of an intraocular lens during a pars plana posterior capsulotomy accomplished by means of a side-firing probe. Epiretinal membrane ablations in air-filled eyes were effectively performed in a gradual fashion without hemorrhage. Conclusions The erbium:YAG laser offers precise and effective tissue cutting and removal in vitreoretinal maneuvers. Further study will determine the role of this technology in vitreoretinal surgery.

Purpose To compare 2 optical patient interface designs used for femtosecond laser–assisted cataract surgery. Setting Optimedica Corp., Santa Clara, California, USA, and Centro Laser, Santo Domingo, Dominican Republic. Design Experimental and clinical studies. Methods Laser capsulotomy was performed during cataract surgery with a curved contact lens interface (CCL) or a liquid optical immersion interface (LOI). The presence of corneal folds, incomplete capsulotomy, subconjunctival hemorrhage, and eye movement during laser treatment were analyzed using video and optical coherence tomography. The induced rise of intraocular pressure (IOP) was measured in porcine and cadaver eyes. Results Corneal folds were identified in 70% of the CCL cohort; 63% of these had areas of incomplete capsulotomies beneath the corneal folds. No corneal folds or incomplete capsulotomies were identified in the LOI cohort. The mean eye movement during capsulotomy creation (1.5 sec) was 50 μm with a CCL and 20 μm with an LOI. The LOI cohort had 36% less subconjunctival hemorrhage than the CCL cohort. During suction, the mean IOP rise was 32.4 mm Hg ± 3.4 (SD) in the CCL group and 17.7 ± 2.1 mm Hg in the LOI group. Conclusions Curved contact interfaces create corneal folds that can lead to incomplete capsulotomy during laser cataract surgery. A liquid interface eliminated corneal folds, improved globe stability, reduced subconjunctival hemorrhage, and lowered IOP rise. Financial Disclosure Drs. Talamo, Culbertson, Batlle, Feliz, and Palanker are consultants to and Messrs. Gooding, Angeley, Schuele, Marcellino, and Andersen, and Ms. Essock-Burns are employees of Optimedica Corp., Sunnyvale, California, USA.

AIMS: To quantify the 20-ms Pattern Scan Laser (Pascal) panretinal laser photocoagulation (PRP) ablation dosage required for regression of proliferative diabetic retinopathy (PDR), and to explore factors related to long-term regression. METHODS: We retrospectively studied a cohort of patients who participated in a randomised clinical trial, the Manchester Pascal Study. In all, 36 eyes of 22 patients were investigated over a follow-up period of 18 months. Primary outcome measures included visual acuity (VA) and complete PDR regression. Secondary outcomes included laser burn dosimetry, calculation of retinal PRP ablation areas, and effect of patient-related factors on disease regression. A PDR subgroup analysis was undertaken to assess all factors related to PDR regression according to disease severity. RESULTS: There were no significant changes in logMAR VA for any group over time. In total, 10 eyes (28%) regressed after a single PRP. Following top-up PRP treatment, regression rates varied according to severity: 75% for mild PDR (n=6), 67% for moderate PDR (n=14), and 43% in severe PDR (n=3). To achieve complete disease regression, mild PDR required a mean of 2187 PRP burns and 264 mm(2) ablation area, moderate PDR required 3998 PRP burns and area 456 mm(2), and severe PDR needed 6924 PRP laser burns (836 mm(2); P

To compare outcomes of selective laser trabeculoplasty (SLT) with drug therapy for glaucoma patients in a prospective randomized clinical trial.Sixty-nine patients (127 eyes) with open-angle glaucoma or ocular hypertension were randomized to SLT or medical therapy. Target intraocular pressure (IOP) was determined using the Collaborative Initial Glaucoma Treatment Study formula. Patients were treated with SLT (100 applications 360 degrees) or medical therapy (prostaglandin analog). Six visits over 1 year followed initial treatment. If target IOP range was not attained with SLT, additional SLT was the next step, or in the medical arm additional medications were added.IOP; secondary: number of steps.Sixty-nine patients were treated. Data collection terminated with 54 patients reaching 9 to 12-months follow-up. Twenty-nine patients were in the SLT group, 25 patients in the medical group. Baseline mean IOP for all eyes was 24.5 mm Hg in the SLT group, 24.7 mm Hg in the medical group. Mean IOP (both eyes) at last follow-up was 18.2 mm Hg (6.3 mm Hg reduction) in the SLT arm, 17.7 mm Hg (7.0 mm Hg reduction) in the medical arm. By last follow-up, 11% of eyes received additional SLT, 27% required additional medication. There was not a statistically significant difference between the SLT and medication groups.IOP reduction was similar in both arms after 9 to 12-months follow-up. More treatment steps were necessary to maintain target IOP in the medication group, although there was not a statistically significant difference between groups. These results support the option of SLT as a safe and effective initial therapy in open-angle glaucoma or ocular hypertension.

PURPOSE To investigate the effects of panretinal photocoagulation (PRP) on macular thickness and macular nerve fiber layer thickness in eyes with proliferative diabetic retinopathy. METHODS Single-center, randomized clinical trial (n = 40 eyes). Proliferative diabetic retinopathy was treated with 1,500 burns given as Pascal 20-millisecond single-session PRP (SS-PRP) or as multiple-session PRP (100 milliseconds, MS-PRP) over a 4-week period. The main outcome measures included optical coherence tomography measurements of total retinal thickness and nerve fiber layer at the macula, visual acuity, and proliferative diabetic retinopathy regression and were recorded at baseline, 4 weeks, and 12 weeks. Optic disk photographs were graded by masked a glaucoma specialist. RESULTS At 12 weeks, in the SS-PRP group, there was no significant change in total nerve fiber layer thickness from baseline (4 weeks; +7.2 μm, P = 0.78; 12 weeks, -1.8 μm, P = 0.95). There was a significant increase in total retinal thickness for the MS-PRP group at 4 weeks from baseline (96 ± 17 μm; P < 0.001) and at 12 weeks (56 ± 21 μm; P = 0.0167). After 4 weeks in the MS-PRP group, total nerve fiber layer thickness increased significantly by 31 ± 54 μm (P = 0.029) from baseline, with a significant reduction at 12 weeks from baseline (35 ± 63 μm; P = 0.034). There was no change among groups for optic nerve appearance postlaser. At 12 weeks, the mean visual acuity was 81 ± 6 letters (SS-PRP group), compared with 77 ± 15 letters in the MS-PRP group (95% confidence interval, 5.2 to 9 letters; P = 0.286). For the SS-PRP group, a positive effect on proliferative diabetic retinopathy regression was observed in 74% of eyes compared with 53% of the eyes in the MS-PRP group (P = 0.31). CONCLUSION Compared with 20-millisecond SS-PRP, eyes treated with conventional 100-millisecond single-spot delivered over multiple sessions showed increased total macular thickness at 4 weeks, with a thinning of macular nerve fiber layer at 12 weeks.

PURPOSE.To correlate in vivo spatial and spectral morphologic changes of short- to long-pulse 532 nm Nd:YAG retinal laser lesions using Fourier-domain optical coherence tomography (FD OCT), autofluorescence (AF), fluorescein angiography (FA), and multispectral imaging. METHODS.Ten eyes with treatment-naive preproliferative or proliferative diabetic retinopathy were studied. A titration grid of laser burns at 20, 100, and 200 milliseconds was applied to the nasal retina and laser fluence titrated to produce four grades of laser lesion visibility: subvisible (SV), barely visible (BV, light-gray), threshold (TH, gray-white), and suprathreshold (ST, white). The AF, FA, FD-OCT, and multispectral imaging were performed 1 week before laser, and 1 hour, 4 weeks, and 3 and 6 months post-laser. Multispectral imaging measured relative tissue oxygen concentration. RESULTS.Laser burn visibility and lesion size increased in a linear relationship according to fixed fluence levels. At fixed pulse durations, there was a semilogarithmic increase in lesion size over 6 months. At 20 milliseconds, all grades of laser lesion were reduced significantly in size after 6 months: SV, 51%; BV, 54%; TH, 49%; and ST, 50% (P!0.001), with retinal pigment epithelial proliferation and photoreceptor infilling. At 20 milliseconds, there was healing of photoreceptor inner segment/ outer segment junction layers compared with 100- and 200millisecond lesions. Significant increases in mean tissue oxygenation (range, four to six units) within the laser titration area and in oxygen concentration across the laser lesions (P! 0.01) were detected at 6 months. C ONCLUSIONS.For patients undergoing therapeutic laser, there may be improved tissue oxygenation, higher predictability of burn morphology, and more spatial localization of healing responses of burns at 20 milliseconds compared with longer pulse durations over time. (Invest Ophthalmol Vis Sci.2011; 52:994‐1002) DOI:10.1167/iovs.10-6309

About a third of people in the developed world will undergo cataract surgery in their lifetime. Currently, cataract surgery is a manual procedure highly dependent on the surgical skills and complicating factors. We developed and tested an image-guided laser system to improve the precision and reproducibility of cataract surgery. A long-range Optical Coherence Tomography automatically discerns the anterior and posterior surfaces of the lens and cornea, and a co-registered femtosecond laser then performs capsulotomy, lens segmentation and corneal incisions. Capsular strength following laser capsulotomy and mechanical capsulorhexis were compared on cadaveric eyes, and retinal safety was verified on rabbits. 50 patients have undergone cataract surgery using the laser system. Eyes were examined ophthalmoscopically, and extracted capsules were analyzed using histology and SEM.

About one-third of people in the developed world will undergo cataract surgery in their lifetime. Although marked improvements in surgical technique have occurred since the development of the current approach to lens replacement in the late 1960s and early 1970s, some critical steps of the procedure can still only be executed with limited precision. Current practice requires manual formation of an opening in the anterior lens capsule, fragmentation and evacuation of the lens tissue with an ultrasound probe, and implantation of a plastic intraocular lens into the remaining capsular bag. The size, shape, and position of the anterior capsular opening (one of the most critical steps in the procedure) are controlled by freehand pulling and tearing of the capsular tissue. Here, we report a technique that improves the precision and reproducibility of cataract surgery by performing anterior capsulotomy, lens segmentation, and corneal incisions with a femtosecond laser. The placement of the cuts was determined by imaging the anterior segment of the eye with integrated optical coherence tomography. Femtosecond laser produced continuous anterior capsular incisions, which were twice as strong and more than five times as precise in size and shape than manual capsulorhexis. Lens segmentation and softening simplified its emulsification and removal, decreasing the perceived cataract hardness by two grades. Three-dimensional cutting of the cornea guided by diagnostic imaging creates multiplanar self-sealing incisions and allows exact placement of the limbal relaxing incisions, potentially increasing the safety and performance of cataract surgery.

To evaluate pain responses following Pascal 20 ms multi-spot and 100 ms single-spot panretinal photocoagulation (PRP).Single-centre randomised clinical trial. 40 eyes of 24 patients with treatment-naive proliferative diabetic retinopathy randomised to 20 and 100 ms PRP under topical 0.4% oxybuprocaine. A masked grader used a pain questionnaire within 1 h (numerical pain score (NPS)) and 1 month after treatment (numerical headache score (NHS)). Primary outcome measure was NPS immediately post-PRP. Secondary outcome measures were mean NHS scores and levels of photophobia reported within 4 weeks of primary PRP.Mean laser fluence was significantly lower using 20 ms PRP (4.8 J/cm²) compared to 100 ms PRP (11.8 J/cm²); p0.001). Mean NPS scores for treatment were 2.4 (2.3) (mild) for 20 ms PRP group compared to 4.9 (3.3) (moderate) in 100 ms PRP group-a significant difference (95% CI 4.3 to 0.68; p = 0.006). Mean NHS score within 1 month was 1.5 (2.7) in 20 ms PRP group compared to 3.2 (3.5) in the 100 ms PRP group (p0.05). The median duration of photophobia after 20 ms PRP was 3 h, and significantly less compared to 100 ms PRP after which 72 h of photophobia was reported (p0.001).Multi-spot 20 ms PRP was associated with significantly lower levels of anxiety, headache, pain and photophobia compared to 100 ms single-spot PRP treatment. Possible reasons include lower fluence, shorter-pulse duration, and spatial summation of laser nociception with multi-spot Pascal technique.

Background/aims The pattern scan laser photocoagulator (PASCAL) is a novel laser device that uses 10–30 ms pulse duration for retina photocoagulation. The aim of this study was to analyse the safety profile of this approach. Methods This was a retrospective study. We reviewed the clinical records of all laser sessions performed with PASCAL from November 2007 to July 2008. Where there were any complications, we recorded the laser parameters, type, affected retina region, postoperative interval and treatment if required. Results There were 1301 consecutive cases. Complications included 17 cases of retinal bleeding (1.3%), two cases of choroidal detachment (0.15%) and one case of exudative retinal detachment (0.07%). There was no statistical difference between the laser parameters used in patients with or without complications. Conclusion The laser parameters for PASCAL are safe. The complications and adverse effects encountered in this series are similar to those reported in other studies.

To investigate the effects of pattern scanning laser (Pascal; OptiMedica, Santa Clara, California) multispot panretinal photocoagulation given in a single-session (SS-PRP) vs single-spot multiple-session PRP (MS-PRP) on proliferative diabetic retinopathy (PDR).Single-center, randomized clinical trial of 40 eyes. Proliferative diabetic retinopathy was treated with a 400-mum spot size in 1500 burns given either as Pascal in 20-millisecond SS-PRP or in 3 sessions (100-millisecond MS-PRP) during a 4-week period. Visual acuity, central subfield retinal thickness (CRT), and 24-2 Swedish interactive thresholding algorithm visual fields were recorded at baseline and 4 and 12 weeks.Central subfield retinal thickness, mean deviation, and PDR grade at 12 weeks.There was a significant increase in mean CRT with MS-PRP (22 mum at 4 weeks, 95% CI, -32.25 to -10.75; 20 mum at 12 weeks, 95% CI, -28.75 to -10.82; P.001) and no significant increase in the SS-PRP group. The mean deviation increased significantly in the SS-PRP group after 4 weeks (0.73 dB, P = .048), with no significant changes in either group at other points. A positive effect on PDR was observed in 74% of eyes in the SS-PRP group vs 53% in the MS-PRP group (P = .31). Mean treatment time for SS-PRP was 5.04 minutes (SD, 1.5 minutes) compared with 59.3 (SD, 12.7 minutes) in the MS-PRP group (P.001).There were no adverse outcomes (CRT, visual acuity, or visual field) from using multispot SS-PRP vs single-spot MS-PRP at 12 weeks postlaser, and treatment times were significantly shorter for multispot SS-PRP. Pascal SS-PRP was as effective as MS-PRP in the treatment of PDR.Twenty-millisecond Pascal SS-PRP may be safely and rapidly performed in 1500 burns with a similar efficacy to conventional MS-PRP. TRIAL IDENTIFIER: Research and Development Office PIN R00037, Central Manchester University Hospitals Foundation Trust.

Aim: To report the evolution of pattern scanning laser (Pascal) photocoagulation burns in the treatment of diabetic retinopathy, using Fourier-domain optical coherence tomography (FD-OCT) and fundus autofluorescence (AF), and to evaluate these characteristics with clinically visible alterations in outer retina (OR) and retinal pigment epithelium (RPE). Methods: Standard red-free and colour fundus photography (FP), FD-OCT, and fundus camera-based AF were performed in 17 eyes of 11 patients following macular and panretinal photocoagulation (PRP). Results: One hour following Pascal application, visibility of threshold burns on FP was incomplete. AF enabled visualisation of complete treatment arrays at 1 h, with hypoautofluorescence at sites of each laser burn. AF signals accurately correlated with localised increased optical reflectivity within the outer retina on FD-OCT. AF signals became hyperautofluorescent at 1 week, and corresponded on FD-OCT to defects at the junction of the inner and outer segments of the photoreceptors (JI/OSP) and upper surface of RPE. A 10 ms macular laser pulse produced a localised defect at the level of JI/OSP and RPE. Macular and 20 ms PRP burns did not enlarge at 1 year’s and 18 months’ follow-up respectively. Conclusions: We report the in vivo spatial localisation and clinical correlation of medium-pulse Pascal photocoagulation burns within outer retina and RPE, using high-resolution FD-OCT and AF. Ophthalmoscopically invisible and threshold Pascal burns may be accurately localised and mapped by AF and FD-OCT, with monitoring over time.

To test the hypothesis that trabecular meshwork endothelial cells (TMEs) regulate aqueous outflow by actively releasing ligands that upon binding to Schlemm's canal endothelial cells (SCEs) increase transendothelial flow, thereby facilitating the egress of aqueous.We tested our hypothesis by (1) activating the TMEs in vitro using a laser procedure known to increase aqueous outflow in vivo; (2) demonstrating that lasered TMEs become activated at the genome-wide level and synthesize ligands; (3) ascertaining that media conditioned by laser-activated TMEs and ligands therein increase transendothelial flow when added to SCEs; and (4) determining that ligands identified as synthesized by TMEs increase permeability when added to SCEs.We find that adding either media conditioned by lasered TMEs or ligands synthesized by TMEs to naïve control SCEs increases permeability. Adding media boiled, diluted, or conditioned by nonlasered TMEs abrogates these permeability effects. Media conditioned by either lasered TMEs or SCEs (TME-cm/SCE-cm), when added to untreated controls of each cell type, induce congruous gene expression and flow effects: TME-cm induces far more differentially expressed genes (829 in control TMEs and 1,120 in control SCEs) than does the SCE-cm (12 in control TMEs and 328 in control SCEs), and TME-cm also increases flow much more (more than 11-fold in control TMEs and more than fourfold in control SCEs) than does the SCE-cm (fivefold in control TMEs and twofold in control SCEs).As postulated, the TMEs release factors that regulate SCE permeability. Derangement of this TME-driven process may play an important role in the pathogenesis of glaucoma. Ligands identified, which regulate permeability, have potential use for glaucoma therapy.

In this paper, we present our findings of the effect of the Erbium:YAG laser on cornea, trabecular meshwork, and retinal tissue. We believe the laser is a safe and effective cutting tool with tremendous potential for surgical application.

The Erbium:YAG laser may be an effective laser for use in cataract surgery. At 2.94 mm the energy is maximally absorbed by water thereby efficiently disrupting tissue with minimal surrounding thermal damage. The laser may be safer to use in the eye than conventional ultrasonic emulsifiers. Preliminary clinical studies of the safety and efficacy have begun.

Purpose: To compare the potential for thermal injury to ocular structures resulting from phacoemulsification ultrasound energy and erbium:YAG (Er:YAG) laser output. Setting: Morse Laser Laboratory, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston. Methods: Ultrasonic phacoemulsification energy and Er:YAG laser output (10 J/cm2, 10 Hz, 0.3 watts) sufficient for lens removal were applied to model systems and human cadaver eyes. Temperatures were measured with ultrafine thermocouples interfaced to a microcomputer data acquisition system. Results: Although greater than 95% of energy from laser output is converted to thermal energy, temperature rise in model systems and cadaver eyes was 10 to 15 times greater after pulsed application of ultrasound energy than after Er:YAG laser application. At 100% power, ∼4 watts of ultrasound power is converted to heat. Temperature rise following both laser and ultrasound applications decreased with irrigation in cadaver eyes and increasing volume in a model system. With continuous irrigation (20 cc/min), the temperature rise at 2 minutes measured at the corneal endothelial surface, within the corneal stroma, and in the anterior chamber angle of cadaver eyes was ∼0.5 degrees Celsius (°C) after laser application and 7.0°C after ultrasound application. Without irrigation, temperatures rose 2.5°C after laser application and 35.0°C after ultrasound application. Conclusion: At operating parameters sufficient for lens removal, the Er:YAG laser imparted less thermal energy to whole eyes and model systems than ultrasonic phacoemulsification.

The safe and effective use of lasers in medicine and surgery requires that the operator understands the various interactions that occur when laser light is incident upon biological tissue. Incident laser radiation can be absorbed at the surface or the light energy can be absorbed throughout the bulk of the tissue with a distribution depending upon the degree of tissue transparency. When transmitted into deeper layers, the laser radiation will be redirected (Figure 3.1) by reflection and scattering. The relative contribution of each of these optical phenomena varies with the laser wavelength and the type of tissue.

Purpose To investigate the morphologic features and clinical efficacy of barely visible Pascal (Optimedica Corporation) photocoagulation burns in diabetic macular edema (DME) using Fourier-domain optical coherence tomography (FD OCT) and fundus autofluorescence (AF). Design Interventional case series. Methods Retrospective evaluation of 10 eyes with newly diagnosed DME that underwent barely visible Pascal photocoagulation using an array of 10-μm, 10-millisecond photocoagulation burns. FD OCT and camera-based AF was performed at baseline and at 1 hour, 2 weeks, 4 weeks, and 12 weeks after laser. Changes in retinal thickening after laser treatment were measured using retinal thickness maps within the treated sector and the central foveal subfield. Results At 1 hour after treatment, burns were visualized partially with clinical biomicroscopy. AF demonstrated spots lacking autofluorescence that confirmed effective laser uptake within the Pascal arrays. Sequential changes in hyperreflectivity on FD OCT correlated with morphologic alterations seen on AF. Burns became increasingly hyperautofluorescent between 2 and 4 weeks. There were significant reductions in the retinal thickness within treated sectors on FD OCT at 2 weeks (26 ± 32 μm; P = .012) and 3 months after laser (20 ± 21 μm; P = .02) compared with baseline. Clinical biomicroscopic reduction of DME was the most common finding in 80%. Conclusions Barely visible 10-millisecond Pascal laser seems to produce an effect at the level of the inner and outer photoreceptor segments and apical retinal pigment epithelium, with minimal axial and lateral spread of burns. FD OCT confirmed spatial localization of AF signal changes that correlated with laser burn–tissue interactions over 3 months. The technique of lower-fluence barely visible 10-millisecond laser may reduce retinal edema within affected sectors and effectively treat DME with minimization of scar formation.

To compare in vivo burn morphologic features and healing responses of Pascal 20- and 100-millisecond panretinal photocoagulation (PRP) burns in proliferative diabetic retinopathy.Prospective randomized controlled trial with 24 eyes assigned to either 20- or 100-millisecond Pascal PRP. Fundus autofluorescence and Fourier domain optical coherence tomography (FD-OCT) were performed 1 hour and 2 and 4 weeks after treatment. Main outcome measures included burn morphologic features on FD-OCT and greatest linear diameter (GLD) of laser burns as evaluated in 6 standard Early Treatment of Diabetic Retinopathy Study photographic fields using autofluorescence.The contemporaneous increase in autofluorescence is observed with increasing pulse duration. Differences in mean GLD between 100- and 20-millisecond burns were 63 mum at 1 hour and 198 mum at 4 weeks (P.001 for both). At 4 weeks, all burns corresponded to defects at the junction of inner and outer segments of photoreceptors (JI/OSP) and apical retinal pigment epithelium. After 4 weeks, the GLD of 20-millisecond burns reduced significantly by 35% (P.001), with no change in 100-millisecond burns.All burns initially appear as equivalent square-edged, columnar foci of hyperreflectivity in the outer retina. Pascal 20-millisecond burns progressively reduce in size, and this suggests a novel healing response localized to the JI/OSP and apical retinal pigment epithelium. The higher-fluence 100-millisecond burns develop larger defects due to thermal blooming and collateral damage.